Energy storage device

Abstract

The energy storage device (1) comprises an energy storage module (10) and a housing (110). The energy storage module (10) comprises a plurality of cells (50). The housing (110) comprises a first wall (111), a pair of second walls (112), and a first reinforcement element (120). The first reinforcement element (120) is attached to the first wall (111). The first reinforcement element (120) extends along a first direction (D1). The first reinforcement element (120) is stiffer than the first wall (111) and the pair of second walls (112). The first reinforcement element (120) comprises a first region (121) and a second region (122). The first region (121) extends in the first direction (D1). The second region (122) is aligned with the first region (121) in the first direction (D1). The second region (122) extends in the first direction (D1). The second region (122) is less stiff than the first region (121).

Description

CROSS REFERENCE TO RELATED APPLICATIONSThis non-provisional application is based on Japanese Patent Application No. 2024-006554 filed with the Japanese Patent Office on Jan. 19, 2024, the entire contents of which are hereby incorporated by reference.BACKGROUNDField FieldThe present disclosure relates to an energy storage device.Description of the Prior ArtJapanese Patent Application No. 2018-144700 discloses a battery pack in which a battery is accommodated. A reinforcing frame is disposed at a rear edge of the battery pack and is configured to extend along at least a rear end surface in the width direction of the vehicle.SUMMARYIn the conventional energy storage device, the reinforcing member can be deformed in an arc shape under load with both ends of the reinforcing member serving as fulcrums. The deformed reinforcement member and a portion of the battery pack adjacent to the deformed reinforcement member may exert a local load on the cells of the energy storage module in the battery pack.The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide an energy storage device capable of preventing a local load from being applied to cells of an energy storage module.The energy storage device according to an aspect of the present disclosure includes an energy storage module and a housing.The energy storage module includes a plurality of cells. The plurality of cells are stacked in the first direction. The housing houses the energy storage module. The housing includes a first wall, a pair of second walls, and a first reinforcement member. The first wall is located at least on one side of the energy storage module in a second direction crossing the first direction. The first wall extends along the first direction. The pair of second walls are respectively located on both sides of the energy storage module in the first direction. The pair of second walls extend in the second direction. The pair of second walls are connected to both ends of the first wall, respectively. The first reinforcement member is attached to the first wall. The first reinforcing member extends in the first direction. The first reinforcement member is more rigid than the first wall and the pair of second walls. The first reinforcement element includes a first region and a second region. The first region extends in the first direction. The second region is aligned with the first region in the first direction. The second region extends in the first direction. The second region is less stiff than the first region.According to the configuration described above, when a load is applied from a second direction side to the second region of the first reinforcing member, the entire second region is shifted toward the energy storage module. The shifted second region comes into contact with the plurality of cells stacked together with the first wall in the first direction. Therefore, the load acting on the second region of the first reinforcing member can be distributed to the plurality of cells. In other words, according to the above-described configuration, it is possible to prevent the first reinforcing member from being deformed in an arc shape with the pair of second walls serving as a fulcrum. In this way, the cells of the energy storage module can be prevented from being subjected to a local load by the deformed first reinforcing element and the first wall.In the above-mentioned energy storage device, the second region of the first reinforcing member may be located on an outer surface of the first wall at the center of the first direction.According to the configuration described above, when a load is applied to the second region, the entire second region is more easily displaced because the second region is at a position relatively far from the pair of second walls. Accordingly, it is also possible to prevent the first reinforcing member and the first wall from being deformed in an arc shape. The load acting on the second region of the first reinforcing member may be dispersed through the plurality of cells.In addition, the length of the second region in the first direction may be half or more of the length of the first reinforcing member.According to the configuration described above, even if the position of the maximum load applied to the first reinforcing member is unevenly distributed in the first direction, the entire second region can be displaced by the load applied to the first reinforcing member. Therefore, the load applied to the first reinforcing member can be effectively dispersed to the plurality of cells.In the above-mentioned energy storage device, the housing may further include a pair of second reinforcement members. The pair of second reinforcement members may be provided on the pair of second walls, respectively. The pair of second reinforcement members may be more rigid than the first wall and the pair of second walls. The second region may be less rigid than the pair of second reinforcement members.According to the configuration described above, the strength of the second wall can be improved by the second reinforcing member, whereby the strength of the housing can be improved. Since the first reinforcing member includes the second region that is less rigid than the second reinforcing member, the first reinforcing member can be prevented from being deformed in an arc shape with the pair of second reinforcing members serving as fulcrums.In addition, the pair of second reinforcement members may be spaced apart from the first reinforcement member. With this arrangement, the first reinforcing member can be further prevented from being deformed in an arc shape when the pair of second reinforcing members function as fulcrums.In the above-mentioned energy storage device, the housing may further include a third wall. The third wall may be located on the other side of the energy storage module in the second direction. The third wall may extend along the first direction. The pair of second walls may be connected to both ends of the third wall, respectively. The housing may further include a third reinforcement member. The third reinforcing member may be attached to the third wall. The third reinforcement member may extend along the first direction. The third reinforcement member may be more rigid than the third wall and the pair of second walls. The second region may be less rigid than the third reinforcing member.According to the configuration described above, it is possible to improve the rigidity of the entire housing in the first direction. When a load is applied from the third reinforcing member side in the second direction, the second region of the first reinforcing member is deformed, which prevents the third reinforcing member and the third wall from being deformed in an arc shape.In the above-mentioned energy storage device, each of the plurality of cells may include an electrode assembly and a cell case. The electrode assembly may include a positive electrode layer, a negative electrode layer, and a separator. The cell case may house the electrode assembly. The positive electrode layer and the negative electrode layer may be stacked in the first direction with the separator interposed therebetween.When a cell having the above-described configuration is compressed to deform in the second direction, an internal short circuit may occur. However, since the load applied to a cell is reduced by the second region, the compressive deformation in the second direction is prevented. Therefore, it is possible to prevent occurrence of an internal short circuit in the cell.In the above-mentioned energy storage device, each of the plurality of cells may include an electrode assembly and a cell case. The electrode assembly may include a positive electrode layer, a negative electrode layer, and a separator. The separator may be disposed between the positive electrode layer and the negative electrode layer. The cell case may house the electrode assembly. The electrode assembly may be wound about an axis that is perpendicular to the first direction.When a cell having the above-described configuration is compressed to deform in a direction perpendicular to the first direction, an internal short circuit may occur. However, since the load applied to a cell is reduced by the second region, the compressive deformation in the direction perpendicular to the first direction is prevented. Therefore, occurrence of an internal short circuit in the cell can be prevented.The foregoing and other objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description of the present disclosure when taken in conjunction with the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a schematic diagram of a state in which an energy storage device according to an exemplary embodiment of the present disclosure is mounted on a vehicle; FIG. 2 is a perspective view showing an energy storage device according to an embodiment of the present disclosure; FIG. 3 is a partial perspective view showing a region III of FIG. 2 from another viewpoint; FIG. 4 is a schematic plan view showing a part of the internal structure of the energy storage device; FIG. 5 is an exploded perspective view of a cell; FIG. 6 is a partial cross-sectional view showing an electrode assembly of FIG. 5 taken along line VI-VI; FIG. 7 is an exploded perspective view showing a cell according to a modification; FIG. 8 is a schematic perspective view partially showing a configuration of an energy storage device; FIG. 9 is a schematic plan view of an energy storage device to which a load is attached; FIG. 10 is a perspective view partially showing a configuration of an energy storage device according to a modification; FIG. 11 is a perspective view partially showing a configuration of an energy storage device according to another modification; and FIG. 12 is a schematic cross-sectional view showing a first reinforcing member of FIG. 11 taken along line XII-XII.DESCRIPTION OF THE PREFERRED EMBODIMENTSHereinafter, an energy storage device according to an exemplary embodiment of the present disclosure will be described with reference to the drawings. In the following description of the present disclosure, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description will not be repeated.FIG. 1 is a schematic diagram of a state in which an energy storage device according to an exemplary embodiment of the present disclosure is mounted on a vehicle. The energy storage device 1 can be mounted on a vehicle 5. The vehicle 5 is, for example, a battery-powered electric vehicle (BEV). The vehicle 5 may also be another type of electric vehicle, such as a plug-in hybrid vehicle (PHEV).When the energy storage device 1 is mounted on the vehicle 5, a first direction D 1 of the energy storage device 1 is typically the left-right direction of the vehicle 5. a second direction D 2 of the energy storage device 1 is typically the front-rear direction of the vehicle 5. a third direction D 3 of the energy storage device 1 is typically the vertical direction.The second direction D 2 crosses the first direction D 1. In particular, the second direction D 2 is perpendicular to the first direction D 1. The third direction D 3 crosses both the first direction D 1 and the second direction D 2. In particular, the third direction D 3 is perpendicular to the first direction D 1 and the second direction D 2.FIG. 2 is a perspective view showing an energy storage device according to an embodiment of the present disclosure. FIG. 3 is a partial perspective view showing a region III of FIG. 2 from another angle. FIG. 4 is a schematic plan view partially showing an internal structure of the energy storage device.As illustrated in FIGS. 2 to 4, the energy storage device 1 includes a plurality of energy storage modules 10 and a housing 110.As illustrated in FIG. 4, the plurality of energy storage modules 10 are oriented in the second direction D 2. In the present exemplary embodiment, the plurality of energy storage modules 10 are aligned only in the second direction D 2.Each of the plurality of energy storage modules 10 includes a plurality of cells 50, a pair of end plates 60, and a retaining member 70.The plurality of cells 50 are stacked in the first direction D 1. Preferably, the plurality of cells 50 are directly stacked one above the other. As a result, the energy density of the energy storage module 10 can be improved. The plurality of cells 50 may be stacked with a spacer interposed between the cells 50 adjacent to each other. The pair of end plates 60 are disposed on both sides of the entire plurality of cells 50 in the first direction D 1. The retaining member 70 applies a predetermined retaining force in the first direction D 1 to the plurality of cells 50 and the pair of end plates 60 stacked on each other.FIG. 5 is an exploded perspective view of a cell. As illustrated in FIG. 5, each cell 50 includes an electrode assembly 51 and a cell case 52.FIG. 6 is a partial cross-sectional view showing the electrode assembly of FIG. 5 along the line VI-VI. As illustrated in FIGS. 5 and 6, the electrode assembly 51 includes a positive electrode layer 51 a, a negative electrode layer 51 b, and a separator 51 c. The positive electrode layer 51 aand the negative electrode layer 51 bare stacked in the first direction D 1 with the separator 51 carranged therebetween.In the present embodiment, the positive electrode layer 51 aincludes a positive electrode current collector foil 511 aand a positive electrode active material layer 512 a. The positive electrode active material layer 512 ais disposed on both surfaces of the positive electrode current collector foil 511 a.The negative electrode layer 51 bincludes a negative electrode current collector foil 511 band a negative electrode active material layer 512 b. The negative electrode active material layer 512 bis disposed on both surfaces of the negative electrode current collector foil 511 b.The separator 51 cisolates the positive electrode layer 51 aand the negative electrode layer 51 bfrom each other. The separator 51 cis made of an insulating material and includes minute voids through which ions can pass.The electrode assembly 51 is not limited to the configuration described above. FIG. 7 is an exploded perspective view of a cell according to a modification. As illustrated in FIG. 7, the electrode assembly 51X may be wound around an axis in the second direction D 2. In the electrode assembly 51X wound as described above, the separator 51 cis disposed between the positive electrode layer 51 aand the negative electrode layer 51 b.The cell case 52 includes the electrode assembly 51.The cell case 52 has a substantially rectangular parallelepiped outer shape. The cell 50 in the present embodiment is a so-called square battery. The size of the cell case 52 in the first direction D 1 is smaller than the size thereof in the second direction D 2 and the size thereof in the third direction D 3. The size of the cell case 52 in the second direction D 2 is larger than the size thereof in the first direction D 1 and the size thereof in the third direction D 3.The cell case 52 is composed of a cell case main body 53 and a lid 54. The cover 54 closes the opening. The main body of the cell case 53 may include one or more openings facing one side or both sides of the second direction D 2.As illustrated in FIGS. 2 to 4, the housing 110 houses a plurality of power storage modules 10. the housing 110 includes a first wall 111, a pair of second walls 112, a third wall 113, a bottom 114, a lid 115, a first reinforcing member 120, a pair of second reinforcing members 130, and a third reinforcing member 140.The first wall 111 is located at least on one side of the energy storage module 10 in the second direction D 2. Specifically, the first wall 111 is located on one side of the entire plurality of energy storage modules 10 in the second direction D 2. The first wall 111 extends in the first direction D 1. The first wall 111 is longer than each of the plurality of energy storage modules 10 in the first direction D 1.The pair of second walls 112 are respectively located on both sides of the energy storage module 10 in the first direction D 1. The pair of second walls 112 are respectively located on both sides of the entire plurality of energy storage modules 10 in the first direction D 1. The pair of second walls 112 extend along the second direction D 2. The pair of second walls 112 is longer than the entire plurality of the energy storage modules 10 in the second direction D 2. The pair of second walls 112 are respectively connected to both ends of the first wall 111 in the first direction D 1. The pair of second walls 112 is integrally formed with the first wall 111.The third wall 113 is located on the other side of the energy storage module 10 in the second direction D 2. Specifically, the third wall 113 is located on the other side of the entire plurality of energy storage modules 10 in the second direction D 2. The third wall 113 extends in the first direction D 1. The third wall 113 is longer than each of the plurality of energy storage modules 10 in the first direction D 1. The pair of second walls 112 are respectively connected to both ends of the third wall 113 in the first direction D 1. The third wall 113 is integrally formed with both pairs of second walls 112.The bottom 114 covers one side of the plurality of energy storage modules 10 in the third direction D 3. The bottom 114 covers a lower surface of the plurality of energy storage modules 10. The bottom 114 is connected to the first wall 111. The bottom 114 is formed integrally with the first wall 111. The bottom 114 is connected to the pair of second walls 112. The bottom 114 is integrally formed with the pair of second walls 112. The bottom 114 is connected to the third wall 113. The bottom 114 is formed integrally with the third wall 113.The cover 115 covers the other side of the plurality of energy storage modules 10 in the third direction D 3. The cover 115 is connected to the first wall 111, the pair of second walls 112, and the third wall 113. The cover 115 is fixed to the first wall 111, the pair of second walls 112, and the third wall 113 by fastening means (not shown) such as screws.The housing 110 (including the first wall 111, the pair of second walls 112, the third wall 113, the bottom 114, and the lid 115) is made of, for example, metal. Specifically, the housing 110 is formed of a steel sheet. The first wall 111, the pair of second walls 112, the third wall 113, and the bottom 114 may be made of a single steel sheet by pressing or the like. Therefore, the thicknesses of the first wall 111, the thicknesses of the pair of second walls 112, the thicknesses of the third wall 113, and the thicknesses of the bottom 114 may be substantially the same.The first reinforcing member 120 is attached to the first wall 111. The first reinforcement member 120 extends in the first direction D 1.The first reinforcement member 120 is more rigid than the first wall 111 and the pair of second walls 112. The first reinforcing member 120 may be made of, for example, a material whose elastic modulus is larger than that of the first wall 111 and the pair of second walls 112. The first reinforcing member 120 may be made of a material having a lower yield strength than that of the first wall 111 and the pair of second walls 112. The first reinforcing member 120 may have a second surface moment less than that of the first wall 111 and the pair of second walls 112. The first reinforcement member 120 may have a lower bending rigidity than the first wall 111 and the pair of second walls 112. The first reinforcing member 120 may be made of a material having a lower tensile strength than that of the first wall 111 and the pair of second walls 112.The first reinforcement member 120 includes a pair of first regions 121 and a second region 122. The two first regions 121 each extend in the first direction D 1. The pair of first regions 121 respectively include both ends of the first reinforcing member 120 in the first direction D 1.The second region 122 is aligned with the first region 121 in the first direction D 1. Specifically, the second region 122 is disposed between the pair of first regions 121. The second region 122 extends in the first direction D 1. The second region 122 of the first reinforcement member 120 is located on the outer surface of the first wall 111 at the center of the first direction D 1. The length of the second region 122 in the first direction D 1 is half or more of the length of the first reinforcing member 120.The second region 122 is less stiff than the first region 121. The method for making the second region 122 less rigid than the first region 121 is not particularly limited. In the present embodiment, the second region 122 may be formed of a material having a smaller elastic modulus than that of the first region 121. The second region 122 may be formed of a material whose yield strength is lower than that of the first region 121. The second region 122 may have a second area torque that is less than that of the first region 121. The second region 122 may have a lower bending stiffness than the first region 121.The second region 122 may be made of a material having a lower tensile strength than that of the first region 121. Specifically, the pair of the first region 121 and the second region 122 may be formed of a plate-processed steel sheet. The pair of the first region 121 and the second region 122 may be made of a hot dip galvanized steel sheet. The tensile strength of the hot dip galvanized steel sheet constituting the pair of first regions 121 is preferably, for example, 440 MPa or more. The tensile strength of the hot dip galvanized steel sheet forming the second region 122 is, for example, less than 440 MPa, and preferably 270 MPa or more. The tensile strength of the material constituting the first region 121 may be 1.1 times or more, 1.2 times or more, or 1.5 times or more than the tensile strength of the material constituting the second region 122.The pair of second reinforcement members 130 are respectively attached to the pair of second walls 112. The pair of second reinforcement members 130 are spaced apart from the first reinforcement member 120.The pair of second reinforcement members 130 is more rigid than the first wall 111 and the pair of second walls 112. For example, the second reinforcing member 130 may be made of a material whose modulus of elasticity is larger than that of the material of which the first wall 111 and the pair of second walls 112 are made. The second reinforcing member 130 may be made of a material whose yield strength is higher than that of the first wall 111 and the pair of second walls 112. The second reinforcing member 130 may have a second surface moment higher than that of the first wall 111 and the pair of second walls 112. The second reinforcing member 130 may have a higher bending rigidity than the first wall 111 and the pair of second walls 112. The second reinforcing member 130 may be made of a material whose tensile strength is higher than that of the first wall 111 and the pair of second walls 112.The second region 122 is less rigid than the pair of second reinforcement members 130. The method of making the second region 122 less rigid than the pair of second reinforcing members 130 is not particularly limited. In the present embodiment, the second region 122 may be formed of a material whose elastic modulus is smaller than that of the pair of second reinforcing members 130. The second region 122 may be made of a material whose yield strength is lower than that of the pair of second reinforcing members 130. The second region 122 may have a second area torque that is less than that of the pair of second reinforcement members 130. The bending rigidity of the second region 122 may be lower than that of the pair of second reinforcement members 130.The second region 122 may be made of a material whose tensile strength is lower than that of the pair of second reinforcing members 130. Specifically, the pair of second reinforcement members 130 may be made of a hot dip galvanized steel sheet. The tensile strength of the hot dip galvanized steel sheet constituting the pair of first regions 121 is preferably, for example, 440 MPa or more.The third reinforcing member 140 is attached to the third wall 113. The third reinforcing member 140 extends in the first direction D 1. The third reinforcing member 140 is spaced apart from the pair of second reinforcing members 130.The third reinforcement member 140 is more rigid than the third wall 113 and the pair of second walls 112. The third reinforcing member 140 may be made of, for example, a material whose elastic modulus is larger than that of the third wall 113 and the pair of second walls 112. The third reinforcing member 140 may be made of a material whose yield strength is higher than that of the third wall 113 and the pair of second walls 112. The third reinforcing member 140 may have a second surface moment higher than that of the third wall 113 and the pair of second walls 112. The third reinforcing member 140 may have a higher bending rigidity than the third wall 113 and the pair of second walls 112. The third reinforcing member 140 may be made of a material whose tensile strength is higher than that of the third wall 113 and the pair of second walls 112.The second region 122 is less rigid than the third reinforcement member 140. The method of making the second region 122 less rigid than the third reinforcing member 140 is not particularly limited. In the present embodiment, the second region 122 may be formed of a material having a smaller elastic modulus than that of the third reinforcing member 140. The second region 122 may be formed of a material whose yield strength is lower than that of the third reinforcing member 140. The second region 122 may have a second area torque that is less than that of the third reinforcing element 140. The second region 122 may have a lower flexural rigidity than the third reinforcement member 140.The second region 122 may be made of a material whose tensile strength is lower than that of the third reinforcing member 140. In particular, the third reinforcing element 140 may be made of a hot dip galvanized steel sheet. The tensile strength of the hot dip galvanized steel sheet constituting the third reinforcing member 140 is preferably, for example, 440 MPa or more.FIG. 8 is a schematic perspective view partially showing the configuration of an energy storage device. As illustrated in FIGS. 4 and 8, the housing 110 further includes a pair of inner side frames 150 and a plurality of inner cross frames 160.The two inner side frames 150 are accommodated inside the housing 110. In other words, the pair of inner side frames 150 are each located inside the pair of second walls 112. The two inner side frames 150 are respectively located on both sides of the entire plurality of power storage modules 10 in the first direction D 1.The plurality of inner transverse frames 160 extends along the first direction D 1. The plurality of inner transverse frames 160 are spaced apart from each other in the second direction D 2. Both ends of the plurality of inner cross frames 160 are connected to the pair of inner side frames 150, respectively. The inner cross frame 160 may be joined to the inner side frame 150 by fastening with a fastening member such as a bolt, welding, or caulking. The plurality of energy storage modules 10 are arranged in the second direction D 2 with the inner cross frame 160 interposed therebetween.Next, the deformation of the energy storage device 1 when a load is applied to the energy storage device 1 from a second direction D 2 side (the first reinforcing member 120) side will be described. FIG. 9 is a schematic plan view showing an energy storage device to which a load is applied. Similar to FIG. 4, FIG. 9 partially illustrates an internal structure of the energy storage device 1.FIG. 9 shows the energy storage device 1 in such a state that one side of the energy storage device 1 in the second direction D 2 is supported by the support member 200 and the other side of the energy storage device 1 in the second direction D 2 is pressed by the pressing member 300.As described above, in the present embodiment, the second region 122 is less stiff than the first region 121. Accordingly, as illustrated in FIG. 9, when a load is applied to the second region 122 of the first reinforcing member 120 from a second direction D 2 side, the entire second region 122 is displaced in the second direction D 2 toward the energy storage module 10. The shifted second region 122 comes into contact with the plurality of cells 50 stacked together with the first wall 111 in the first direction D 1. Therefore, the load applied to the second region 122 of the first reinforcement member 120 may be distributed to the plurality of cells 50. More specifically, the load may be distributed to the plurality of cell housings 52.In other words, according to the configuration described above, the first reinforcing member 120 can be prevented from being deformed in an arc shape with the pair of second walls 112 functioning as fulcrums. Thus, the cells 50 of the energy storage module 10 can be prevented from being locally loaded by the deformed first reinforcing member 120 and the first wall 111.In addition, the second region 122 of the first reinforcement member 120 is located on the outer surface of the first wall 111 at the center of the first direction D 1.According to the above-described configuration, since the second region 122 is located at a position relatively far from the pair of second walls 112, the entire second region 122 is more easily displaced when a load acts on the second region 122. Accordingly, the first reinforcing member 120 and the first wall 111 can also be prevented from being deformed in an arc shape. The load acting on the second region 122 of the first reinforcement member 120 may be distributed through the plurality of cells.In addition, the length of the second region 122 in the first direction D 1 is half or more of the length of the first reinforcing member 120.According to the configuration described above, even if the position of a maximum load applied to the first reinforcing member 120 is unevenly distributed in the first direction D 1, the entire second region 122 can be displaced by the load applied to the first reinforcing member 120. Therefore, the load applied to the first reinforcing member 120 can be effectively dispersed to the plurality of cells.In addition, the pair of second reinforcement members 130 is more rigid than the first wall 111 and the pair of second walls 112. The second region 122 is less rigid than the pair of second reinforcement members 130.According to the configuration described above, the strength of the second wall 112 can be improved by the second reinforcing member 130, and thereby the strength of the housing 110 can be improved. Since the first reinforcing member 120 includes the second region that is less rigid than the second reinforcing member 130, the first reinforcing member 120 can be prevented from being deformed in an arc shape with the pair of second reinforcing members 130 serving as fulcrums.In addition, the pair of second reinforcement members 130 are spaced apart from the first reinforcement member 120. This arrangement can further prevent the first reinforcing member 120 from being deformed in an arc shape with the pair of second reinforcing members 130 serving as fulcrums.In addition, the third reinforcing member 140 is more rigid than the third wall 113 and the pair of second walls 112. The second region 122 is less rigid than the third reinforcement member 140.According to the configuration described above, it is possible to improve the rigidity of the entire housing 110 in the first direction D 1. When a load is applied from the third reinforcing member 140 side in the second direction D 2, the second region 122 of the first reinforcing member 120 is deformed, which prevents the third reinforcing member 140 and the third wall 113 from being deformed in an arc shape.Further, in each of the plurality of cells 50, the positive electrode layer 51 aand the negative electrode layer 51 bmay be stacked in the first direction D 1 with the separator 51 cbeing interposed therebetween.When the cell 50 having the above-described configuration is compressed to deform in the second direction D 2, an internal short circuit is likely to occur. However, since the load applied to a cell 50 is reduced by the second region 122, the compressive deformation in the second direction D 2 is prevented. Therefore, it is possible to prevent occurrence of an internal short circuit in the cell 50.Further, the electrode assembly 51X in each of the plurality of cells 50X may be wound around an axis perpendicular to the first direction D 1. More specifically, the electrode assembly 51X may be wound around an axis in the second direction D 2.When the cell 50X having the above-described configuration is compressed to deform in a direction (the second direction D 2) perpendicular to the first direction D 1, an internal short circuit may occur. However, since the load applied to a cell 50X is reduced by the second region 122, the compressive deformation in a direction (the second direction D 2) perpendicular to the first direction D 1 is prevented. Therefore, it is possible to prevent occurrence of an internal short circuit in the cell 50X.The second region 122 may be made less rigid than the first region 121, the second reinforcement member 130, and the third reinforcement member 140 by various methods.FIG. 10 is a perspective view partially showing a configuration of an energy storage device according to a modification. As illustrated in FIG. 10, a plurality of through holes 123A may be formed in the second region 122A of the first reinforcing member 120A. Accordingly, the second region 122A may be less rigid than the first region 121A, the second reinforcement member 130, and the third reinforcement member 140. In this case, the elastic modulus or the like of the material constituting the second region 122A may not be smaller than the elastic modulus or the like of the material constituting the first region 121A, the second reinforcing member 130, and the third reinforcing member 140.In the present modification, the plurality of through holes 123A are formed so as to penetrate the first reinforcing member 120A in the second direction D 2. The plurality of through holes 123A may be formed to penetrate the first reinforcing member 120A in the third direction D 3. A plurality of through holes may also be formed in the first region 121A, but the diameter of each through hole formed in the first region 121A is preferably smaller than that of each through hole 123A. The distance between the plurality of through holes formed in the first region 121A is preferably larger than the distance between the plurality of through holes 123A in the first direction D 1.FIG. 11 is a perspective view partially showing a configuration of an energy storage device according to another modification. FIG. 12 is a schematic cross-sectional view showing a first reinforcing member of FIG. 11 taken along line XII-XII. As illustrated in FIGS. 11 and 12, a notch 124B extending along the first direction D 1 may be formed in the second region 122B of the first reinforcement member 120B. Thus, the second region 122B may be less stiff than the first region 121B and the second reinforcement member 130. As illustrated by the broken line in FIG. 12, the second region 122B collapses around the notch 124B when a load is applied from a side of the second direction D 2. In this case, the elastic modulus or the like of the material constituting the second region 122B may not be smaller than the elastic modulus or the like of the material constituting the first region 121B, the second reinforcing member 130, and the third reinforcing member 140.In the present modification, the notch 124B does not penetrate the first reinforcing member 120B, but may penetrate the first reinforcing member 120B. The notch 124B is provided on the first reinforcing member 120B on one side of the housing 110, but may be provided on the first reinforcing member 120B on the other side of the housing 110.In the above-described embodiments, appropriate combinations of components are also originally provided in each embodiment.Although the embodiments of the present disclosure have been described, it should be understood that the embodiments disclosed herein have been presented for purposes of illustration and description, but are not limited in all aspects. It is intended that the scope of the present disclosure not be limited to the above description, but be defined by the scope of the claims and include all changes that come within meaning and range of the claims.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedJP 2024-006554

[0001] JP 2018-144700

[0003]

Claims

An energy storage device, comprising: an energy storage module (10) including a plurality of cells (50) stacked on each other in a first direction (D1); and a housing (110) accommodating the energy storage module (10), the housing (110) including: a first wall (111) located at least on one side of the energy storage module (10) in a second direction (D2) crossing the first direction (D1) and extending along the first direction (D1); a pair of second walls (112) located respectively on both sides of the energy storage module (10) in the first direction (D1), extending along the second direction (D2), and respectively connected to both ends of the first wall (111); and a first reinforcing member (120) provided on the first wall (111), extending along the first direction (D1) and being stiffer than the first wall (111), and the pair of second walls (112), the first reinforcing member (120) comprising: a first region (121) extending in the first direction (D1); and a second region (122) aligned with the first region (121) in the first direction (D1) and extending in the first direction (D1), and the second region (122) being less stiff than the first region (121).The energy storage device of claim 1, wherein the second region (122) of the first reinforcement member (120) is located on an outer surface of the first wall (111) in the middle of the first direction (D1).The energy storage device according to claim 2, wherein a length of the second region (122) in the first direction (D1) is half or more of a length of the first reinforcing member (120).The energy storage device according to any one of claims 1 to 3, wherein the housing (110) further includes a pair of second reinforcing members (130), the pair of second reinforcing members (130) are respectively provided on the pair of second walls (112), extend along the second direction (D2), and are stiffer than the first wall (111) and the pair of second walls (112), and the second region (122) is less stiff than the pair of second reinforcing members (130).The energy storage device of claim 4, wherein the pair of second reinforcement members (130) are spaced apart from the first reinforcement member (120).The energy storage device according to any one of claims 1 to 5, wherein the housing (110) further includes a third wall (113), the third wall (113) is located on the other side of the energy storage module (10) in the second direction (D2) and extends along the first direction (D1), the pair of second walls (112) are respectively connected to both ends of the third wall (113), the housing (110) further includes a third reinforcing member (140), the third reinforcing member (140) is provided on the third wall (113), extends along the first direction (D1) and is stiffer than the third wall (113), and the pair of second walls (112), and the second region (122) is less stiff than the third reinforcing member (140).The energy storage device according to any one of claims 1 to 6, wherein each of the plurality of cells (50) includes: an electrode assembly (51) including a positive electrode layer (51a), a negative electrode layer (51b), and a separator (51c); and a cell case (52) accommodating the electrode assembly (51), the positive electrode layer (51a), and the negative electrode layer (51b) are stacked in the first direction (D1) with the separator (51c) interposed therebetween.The energy storage device according to any one of claims 1 to 6, wherein each of the plurality of cells (50X) includes: an electrode assembly (51X) including a positive electrode layer (51a), a negative electrode layer (51b), and a separator (51c) disposed between the positive electrode layer (51a) and the negative electrode layer (51b); and a cell case (52) accommodating the electrode assembly (51X), the electrode assembly (51X) being wound around an axis in a direction perpendicular to the first direction (D1).

Images