Bipolar battery

Abstract

Provided is a bipolar storage battery that, with a simple configuration, can appropriately externally dissipate heat produced in a cell member. A bipolar storage battery (1) comprises: a plurality of cell members (150) which are each provided with a positive electrode (151) that has a positive electrode active material layer (103), a negative electrode (152) that has a negative electrode active material layer (104), and an electrolytic layer (105) that is interposed between the positive electrode (151) and the negative electrode (152); and a plurality of frame units (110), (120), (130) which form a plurality of cells (C) that individually accommodate the plurality of cell members (150). The cell members (150) are electrically connected to each other in series. Formed on an outside surface of at least one of the plurality of frame units (110), (120), (130) is a depression (160) that is open at that outside surface.

Description

[Technical field]

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

[0002] In recent years, the number of power generation facilities that utilize natural energy such as solar power and wind power has been increasing. In such power generation facilities, since it is not possible to control the amount of power generated, a storage battery is used to level out the power load. That is, when the amount of power generated is greater than the amount of power consumed, the difference is charged to the storage battery, whereas when the amount of power generated is less than the amount of power consumed, the difference is discharged from the storage battery. As the storage battery described above, lead-acid batteries are widely used from the viewpoints of economy and safety, and among them, bipolar lead-acid batteries have attracted attention from the viewpoint of energy density.

[0003] This bipolar lead-acid battery is formed by alternately stacking and assembling a plurality of cell members each having an electrolytic layer between a positive electrode having an active material layer for a positive electrode and a negative electrode having an active material layer for a negative electrode, and a frame unit made of resin that houses the cell members, so that the cell members are connected in series. In this bipolar lead-acid battery, a high cell density is required to increase the energy density. However, the more cells per unit stack in the bipolar lead-acid battery structure, the more serious thermal problems can occur compared to other battery structures. In other words, in a bipolar lead-acid battery, if the heat generated in the active material layer of the cell material by the battery reaction is not provided with an appropriate transmission path to the outside, the heat will remain inside the battery, causing damage to the cell material and degrading the charge / discharge characteristics.

[0004] As a means for appropriately transferring heat generated in the active material layers of the cell members in this bipolar lead-acid battery to the outside, a current collector assembly for a bipolar lead-acid battery, for example, as disclosed in Patent Document 1, has been conventionally known. The current collector assembly for a bipolar lead-acid battery shown in Patent Document 1 includes a conductive silicon substrate and a frame bonded to the conductive silicon substrate, the conductive silicon substrate including one or more thin films that render the surface of the conductive silicon substrate conductive and electrochemically stable in the presence of lead-acid electrolyte chemistry, and the interface between the frame and the conductive silicon substrate is hermetically sealed. The housing includes thermally conductive ribs for heat dissipation bonded to the casing cement and the frame, the frame forming a spacer for electrically insulating the thermally conductive ribs from the conductive silicon substrate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2018-524779 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the conventional current collector assembly for a bipolar lead-acid battery shown in Patent Document 1 has the following problems. That is, in the case of the current collector assembly for a bipolar lead-acid battery shown in Patent Document 1, when the conductive silicon substrate generates heat, the heat is appropriately dissipated to the outside via the heat conductive rib, but an insulating spacer (frame) must be disposed between the conductive silicon substrate and the heat conductive rib for electrical insulation. Therefore, an extra insulating spacer is required, and the configuration of the heat dissipating member becomes complicated.

[0007] In view of the above, an object of the present invention is to provide a bipolar storage battery that can appropriately dissipate heat generated in cell members to the outside using a simple configuration. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present invention provides a bipolar storage battery having the following configurations (1) and (2). (1) A battery comprising: a positive electrode having a positive electrode active material layer, a negative electrode having a negative electrode active material layer, and an electrolytic layer interposed between the positive electrode and the negative electrode, a plurality of cell members arranged in a stacked arrangement with a space therebetween, and a plurality of frame units forming a plurality of cells each housing the plurality of cell members. The cell members are electrically connected in series. (2) At least one of the plurality of frame units has an outer surface formed with a recess that opens to the outer surface. Effect of the Invention

[0009] In the bipolar storage battery according to the present invention, at least one of the frame units has a recess that opens to the outer surface, so that the surface area exposed to the outer surface of the frame unit is increased and heat generated in the positive electrode active material layer and the negative electrode active material layer of the cell member by the battery reaction can be appropriately dissipated to the outside through the recess of the frame unit, thereby suppressing deterioration of the charge / discharge characteristics caused by heat retention inside the battery. Furthermore, since it is only necessary to form a recess that opens to the outer surface of the frame unit, the structure for achieving the heat dissipation function can be simplified. Therefore, according to the bipolar storage battery of the present invention, it is possible to provide a bipolar storage battery that can appropriately dissipate heat generated in the cell members to the outside with a simple configuration.

[0010] Furthermore, in the bipolar storage battery according to the present invention, each of the frame units includes a rim having joint surfaces facing each other in the stacking direction of the cell members, and a recess is formed on the outer surface of the rim of at least one of the frame units, so that the surface area exposed to the outer surface of the rim is increased and heat generated in the positive electrode active material layer and the negative electrode active material layer of the cell members by the battery reaction can be appropriately dissipated to the outside through the recess of the rim, thereby suppressing deterioration of the charge / discharge characteristics caused by heat retention inside the battery. Furthermore, since it is only necessary to form a recess that is open to the outside surface of the rim, the structure for achieving the heat dissipation function can be simplified.

[0011] Furthermore, in the bipolar storage battery according to the present invention, the recess is provided with a reinforcing rib that connects the open edges of the recess and extends in the layer direction of the cell members, thereby increasing the surface area exposed to the outer surface of the rim and enabling heat generated in the positive and negative active material layers of the cell members by the battery reaction to be dissipated more effectively from the recess of the rim to the outside. Furthermore, by providing the recess with a reinforcing rib that extends in the stacking direction of the cell members connecting the open edges of the recess, the mechanical strength can be improved when the frame units are joined at the joining surfaces in the stacking direction. In particular, when joining at the joining surfaces is performed by vibration welding, the rim is pressed in the stacking direction, so providing a reinforcing rib that extends in the stacking direction of the cell members connecting the open edges of the recess improves the mechanical strength, which is of great practical benefit.

[0012] Furthermore, in the bipolar storage battery according to the present invention, the multiple frame units include one or more bipolar plates arranged between adjacent cell members in the stacking direction, a pair of end plates arranged at one end and the other end of the multiple cell members in the stacking direction, and a multiple spacer arranged between adjacent bipolar plates in the stacking direction, between one end plate of the pair of end plates and the bipolar plate, and between the other end plate of the pair of end plates and the bipolar plate, and the multiple cells individually accommodating the multiple cell members are formed by the one or more bipolar plates, the pair of end plates, and the multiple spacers, and each of the one or more bipolar plates, the pair of end plates, and the multiple spacers has joint surfaces facing each other in the stacking direction of the cell members, and a recess is formed on an outer surface of at least one of the multiple spacers. As a result, at least one of the spacers has an outer surface formed with a recess that opens to the outer surface, so that the surface area exposed to the outer surface of the spacer is increased, and heat generated in the positive electrode active material layer and the negative electrode active material layer of the cell member by the battery reaction can be appropriately dissipated to the outside through the recess of the spacer, thereby suppressing deterioration of the charge / discharge characteristics caused by heat retention inside the battery. Furthermore, since it is only necessary to form a recess that opens to the outer surface of the spacer, the structure for achieving the heat dissipation function can be simplified.

[0013] Furthermore, in the bipolar storage battery according to the present invention, the recesses are formed on the outer surface of at least one of the one or more bipolar plates, thereby increasing the surface area exposed to the outer surface of the bipolar plate, and allowing heat generated in the positive electrode active material layer and the negative electrode active material layer of the cell member to be properly dissipated to the outside not only from the recesses of the spacer but also from the recesses of the bipolar plates.

[0014] In addition, in the bipolar storage battery according to the present invention, the recess is provided with a reinforcing rib that extends in the stacking direction of the cell members and connects the open edges of the recess. By providing this reinforcing rib in the recess formed in the spacer, the surface area exposed to the outer surface of the spacer is further increased, and heat generated in the positive electrode active material layer and the negative electrode active material layer of the cell member due to the battery reaction can be more effectively dissipated from the recess of the spacer to the outside. In addition, by providing this reinforcing rib in the recess formed in the bipolar plate, the surface area exposed to the outer surface of the bipolar plate is further increased, and heat generated in the positive electrode active material layer and the negative electrode active material layer of the cell member due to the battery reaction can be more effectively dissipated from the recess of the bipolar plate to the outside. Furthermore, by providing a reinforcing rib in the recess formed in the spacer or the recess formed in the bipolar plate, which extends in the stacking direction of the cell members and connects the open edges of the recess, the mechanical strength can be improved when joining one or more bipolar plates, a pair of end plates, and a plurality of spacers at their joining surfaces in the stacking direction. In particular, when joining at the joining surfaces is performed by vibration welding, each component (bipolar plate, end plate, and spacer) is pressed in the stacking direction, so by providing a reinforcing rib that extends in the stacking direction and connects the open edges of the recess, the mechanical strength can be improved, which is of great practical benefit.

[0015] Furthermore, according to the bipolar lead-acid battery of the present invention, the positive electrode has a positive electrode lead layer and the negative electrode has a negative electrode lead layer, so that in the bipolar lead-acid battery, the heat generated in the cell members can be appropriately dissipated to the outside with a simple configuration. [Brief description of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a bipolar storage battery according to a first embodiment of the present invention. [Diagram 2] 2 is a perspective view of an internal frame unit used in the bipolar storage battery shown in FIG. 1. [Diagram 3] FIG. 4 is a cross-sectional view showing a schematic configuration of a bipolar storage battery according to a second embodiment of the present invention. [Figure 4] FIG. 11 is a perspective view of an inner frame unit used in a bipolar storage battery according to a third embodiment of the present invention. [Diagram 5] FIG. 11 is a cross-sectional view showing a schematic configuration of a bipolar storage battery according to a fourth embodiment of the present invention. [Figure 6] 6 is a perspective view of a spacer used in the bipolar storage battery shown in FIG. 5. [Figure 7] FIG. 11 is a cross-sectional view showing a schematic configuration of a bipolar storage battery according to a fifth embodiment of the present invention. [Figure 8] FIG. 8 is a perspective view of a spacer used in the bipolar storage battery shown in FIG. 7. [Figure 9] FIG. 8 is a perspective view of a bipolar plate used in the bipolar storage battery shown in FIG. 7. [Figure 10] FIG. 13 is a perspective view of a spacer used in a bipolar storage battery according to a sixth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A bipolar storage battery according to an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiment described with reference to the drawings.

[0018] (First embodiment) A bipolar storage battery according to a first embodiment of the present invention will be described with reference to FIGS. The bipolar storage battery 1 shown in FIG. 1 is a bipolar lead-acid battery in which a positive electrode 151 has a positive electrode lead layer 101 and a negative electrode 152 has a negative electrode lead layer 102, and is provided with a plurality of cell members 150, a plurality of internal frame units (frame units) 110, a first end frame unit 120 (frame unit), and a second end frame unit (frame unit) 130. The multiple cell members 150 are stacked and arranged at intervals in the stacking direction (the vertical direction in FIG. 1).

[0019] The multiple inner frame units 110, the first end frame unit 120, and the second end frame unit 130 form multiple cells (spaces) C that individually house multiple cell members 150. Each internal frame unit 110 is composed of a substrate (bipolar plate) 111 having a rectangular planar shape with a positive electrode 151 disposed on one surface and a negative electrode 152 disposed on the other surface, and a rim 112 having, for example, a rectangular frame shape (picture frame shape) provided on the periphery of the substrate 111. The substrate 111 of the internal frame unit 110 is disposed between adjacent cell members 150 in the stacking direction of the cell members 150 (the vertical direction in FIG. 1). The rims 112 of each internal frame unit 110 have joint surfaces 112a that face each other in the stacking direction of the cell members 150 (the vertical direction in FIG. 1).

[0020] The substrate 111 is integrated with the inside of the rim 112. The internal frame unit 110 is made of a sulfuric acid-resistant thermoplastic resin (e.g., polyethylene, polypropylene, polystyrene, polyvinyl chloride, polymethyl methacrylate (acrylic resin), acrylonitrile-butadiene-styrene copolymer (ABS), polyamide (nylon), polycarbonate, etc.). The substrate 111 is located in the middle of the thickness direction of the rim 112 (the vertical direction in FIG. 1). The rim 112 is thicker than the substrate 111.

[0021] The first end frame unit 120 is composed of a first end plate 121 having a rectangular planar shape and a square frame-shaped (picture frame-shaped) rim 122. The first end plate 121 is integrated with the inside of the rim 122. The first end frame unit 120 is made of a thermoplastic resin having sulfuric acid resistance. The first end frame unit 120 surrounds the side surface and the negative electrode 152 side of the cell member 150 at one end side (the lower end side in FIG. 1 ) of the bipolar storage battery 1. A first end plate 121 surrounds the negative electrode 152 side of the cell member 150, and a rim 122 surrounds the side surface of the cell member 150.

[0022] The first end plate 121 is disposed parallel to the base plate 111 of the internal frame unit 110, and the rim 122 is arranged so as to contact the rim 112 of the adjacent internal frame unit 110. In other words, the rim 122 has a joint surface 122a that faces the rim 112 of the internal frame unit 110 in the stacking direction of the cell members 150 (the up-down direction in FIG. 1). The first end plate 121 has a thickness greater than that of the substrate 111. The rim 122 has a thickness greater than that of the first end plate 121. The first end plate 121 is set to be located at one end (the lower end in FIG. 1) in the thickness direction of the rim 122 (the vertical direction in FIG. 1).

[0023] The second end frame unit 130 is composed of a second end plate 131 having a rectangular planar shape and a square frame-shaped (picture frame-shaped) rim 132. The second end plate 131 is integrated with the inside of the rim 132. The second end frame unit 130 is made of a thermoplastic resin having sulfuric acid resistance. The second end frame unit 130 surrounds the side surface and positive electrode 151 side of the cell member 150 at the other end side (the upper end side in FIG. 1 ) of the bipolar storage battery 1. The second end plate 131 surrounds the positive electrode 151 side of the cell member 150, and the rim 132 surrounds the side surface of the cell member 150.

[0024] The second end plate 131 is disposed parallel to the base plate 111 of the internal frame unit 110, and the rim 132 is arranged so as to contact the rim 112 of the adjacent internal frame unit 110. In other words, the rim 132 has a joint surface 132a that faces the rim 112 of the internal frame unit 110 in the stacking direction of the cell members 150 (the up-down direction in FIG. 1). The second end plate 131 has a thickness greater than that of the substrate 111. The rim 132 has a thickness greater than that of the second end plate 131. The second end plate 131 is set to be located at the other end (the upper end in FIG. 1) in the thickness direction of the rim 132 (the vertical direction in FIG. 1).

[0025] A positive electrode lead layer 101 is disposed on one surface of the substrate 111. A negative electrode lead layer 102 is disposed on the other surface of the substrate 111. A positive electrode active material layer 103 is disposed on the positive electrode lead layer 101. A negative electrode active material layer 104 is disposed on the negative electrode lead layer 102. Between the opposing positive electrode active material layer 103 and negative electrode active material layer 104, an electrolytic layer 105 made of a glass fiber mat or the like impregnated with an electrolytic solution such as sulfuric acid is disposed.

[0026] A negative electrode lead layer 102 is disposed on the other surface of the first end plate 121. A negative electrode active material layer 104 is disposed on the negative electrode lead layer 102 on the first end plate 121. An electrolytic layer 105 made of a glass fiber mat or the like impregnated with an electrolytic solution such as sulfuric acid is disposed between the negative electrode active material layer 104 on the first end plate 121 and the positive electrode active material layer 103 of the opposing substrate 111. A positive electrode lead layer 101 is disposed on one surface of the second end plate 131. A positive electrode active material layer 103 is disposed on the positive electrode lead layer 101 on the second end plate 131. An electrolytic layer 105 made of a glass fiber mat or the like impregnated with an electrolytic solution such as sulfuric acid is disposed between the positive electrode active material layer 103 on the second end plate 131 and the negative electrode active material layer 104 of the opposing substrate 111.

[0027] The negative lead layer 102 on the first end plate 121 is provided with a negative terminal 108 that is electrically connected to the outside of the first end plate 121. The positive lead layer 101 on the second end plate 131 is provided with a positive terminal 107 that is electrically connected to the outside of the second end plate 131. In other words, the bipolar storage battery 1 according to the first embodiment comprises a positive electrode 151 having a positive electrode active material layer 103, a negative electrode 152 having a negative electrode active material layer 104, and a plurality of cell members 150 including an electrolytic layer 105 interposed between the positive electrode 151 and the negative electrode 152, and a plurality of frame units (a plurality of internal frame units 110, a first end frame unit 120, and a second end frame unit 130) that form a plurality of cells C that individually accommodate the plurality of cell members 150. The cell members 150 adjacent to each other in the stacking direction are electrically connected in series. Therefore, the substrate 111 interposed between the cell members 150 adjacent to each other in the stacking direction is provided with a means for electrically connecting the positive electrode lead layer 101 and the negative electrode lead layer 102.

[0028] In addition, the joint surfaces 112a of the rims 112 of adjacent internal frame units 110, the joint surfaces 122a of the rims 122 of adjacent first end frame units 120 and the joint surfaces 112a of the rims 112 of the internal frame units 110, and the joint surfaces 132a of the rims 132 of adjacent second end frame units 130 and the joint surfaces 112a of the rims 112 of the internal frame units 110 are joined by adhesive or vibration welding. For example, when joining the joining surfaces 112a of the rims 112 of adjacent internal frame units 110, vibration welding involves pressing one joining surface 112a against the other joining surface 112a and vibrating it to generate frictional heat and melt the one joining surface 112a and the other joining surface 112a.

[0029] In the bipolar storage battery 1 configured in this manner, if the heat generated in the positive electrode active material layer 103 and the negative electrode active material layer 104 of the cell member 150 due to the battery reaction is not provided with an appropriate transmission path to the outside, the heat will remain inside the battery and may damage the cell member 150, resulting in a deterioration in the charge / discharge characteristics. For this reason, in the bipolar storage battery 1 according to the first embodiment, recesses 160 that open to the outer side are formed on the outer sides of all of the multiple frame units (the inner frame unit 110, the first end frame unit 120, and the second end frame unit 130). Specifically, recesses 160 that open to the outer side are formed on the outer side of the rim 112 of each inner frame unit 110, the outer side of the rim 122 of the first end frame unit 120, and the outer side of the rim 132 of the second end frame unit 130.

[0030] The recesses 160 formed on the outer surface of the rim 112 of each internal frame unit 110 are formed in four in each frame portion of the rectangular frame-shaped (picture frame-shaped) rim 112, as shown in FIG. 2 (only two recesses 160 are shown in FIG. 2). Each recess 160 is formed in an elongated rectangular shape extending in the direction in which the frame portion of the rim 112 extends, and has dimensions of length L, depth D, and width W in the stacking direction, and is formed so as to leave the four corner portions 113 of the rim 112 in a square frame shape. The length L, depth D, and width W in the stacking direction of each recess 160 are appropriately determined taking into consideration the heat dissipation characteristics and mechanical strength of the rim 112, and the liquid leakage prevention performance described below.

[0031] In the bipolar storage battery 1 according to the first embodiment, the thickness of the substrate 111 is set to 1 to 10 mm, the height h of the rim 112 is set to 5 to 20 mm, the length d of the rim 112 is set to 100 to 500 mm, the joint width B described below is set to 1 to 20 mm, the length L of each recess 160 is set to 90 to 490 mm, the width W of each recess 160 in the stacking direction is set to 3 to 16 mm, and the depth D of each recess 160 is set to 0.5 to 15 mm. Each recess 160 is formed so as to leave the four corner portions 113 of the square frame-shaped rim 112, but it is also possible to form the recess 160 in the four corner portions 113 as well so that one recess 160 surrounds the entire circumference of the square frame-shaped rim 112.

[0032] Similarly to the recesses 160 of the rim 112, the recesses 160 formed on the outer surface of the rim 122 of the first end frame unit 120 and the outer surface of the rim 132 of the second end frame unit 130 are formed in a rectangular shape that is elongated in the direction in which the frame portions of the rims 122, 132 extend, have a predetermined length, depth, and width in the stacking direction, and are formed so as to leave the four corners of the square-shaped frame-shaped rims 122, 132. The length, depth, and width in the stacking direction of each recess 160 are determined appropriately taking into consideration the heat dissipation characteristics and mechanical strength of the rims 122, 132, and the liquid leakage prevention performance described later. Furthermore, the recesses 160 of the rims 122, 132 may also be formed at the four corners of the square frame-shaped rims 122, 132 so that one recess 160 surrounds the entire circumference of the square frame-shaped rims 122, 132.

[0033] In this way, according to the bipolar storage battery 1 according to the first embodiment, the outer surfaces of all the frame units (the inner frame units 110, the first end frame unit 120, and the second end frame unit 130) are provided with recesses 160 that open to the outer surface. This increases the surface area exposed to the outer surfaces of the frame units (the inner frame units 110, the first end frame unit 120, and the second end frame unit 130), and the heat generated in the positive electrode active material layer 103 and the negative electrode active material layer 104 of the cell member 150 by the battery reaction can be appropriately dissipated to the outside from the recesses 160 of the frame units (the inner frame units 110, the first end frame unit 120, and the second end frame unit 130). This makes it possible to suppress the deterioration of the charge / discharge characteristics caused by the heat staying inside the battery.

[0034] Furthermore, since it is only necessary to form recesses 160 that open to the outer side on the outer sides of the frame units (multiple internal frame units 110, first end frame unit 120, and second end frame unit 130), the configuration for achieving the heat dissipation function can be simplified. Therefore, according to the bipolar storage battery 1 according to the first embodiment, it is possible to provide a bipolar storage battery 1 that can appropriately dissipate heat generated in the cell members 150 to the outside with a simple configuration.

[0035] Furthermore, according to the bipolar storage battery 1 of the first embodiment, each of the multiple frame units (the multiple internal frame units 110, the first end frame unit 120, and the second end frame unit 130) includes rims 112, 122, 132 having joint surfaces 112a, 122a, 132a that face each other in the stacking direction of the cell member 150, and the recesses 160 are formed on the outer surfaces of the rims 112, 122, 132 of all of the multiple frame units (the multiple internal frame units 110, the first end frame unit 120, and the second end frame unit 130). As a result, the surface area exposed on the outer surfaces of the rims 112, 122, 132 is increased, and heat generated in the positive electrode active material layer 103 and the negative electrode active material layer 104 of the cell member 150 due to the battery reaction can be appropriately dissipated to the outside from the recesses 160 of the rims 112, 122, 132. This makes it possible to suppress deterioration of the charge / discharge characteristics caused by heat remaining inside the battery.

[0036] Moreover, since it is only necessary to form the recesses 160 that are open to the outside on the outside surfaces of the rims 112, 122, 132, the structure for achieving the heat dissipation function can be simplified. Also, in order to improve the ability to dissipate heat generated inside the battery to the outside, it is sufficient to reduce the joint width B (see Figs. 1 and 2) of the joint surfaces 112a, 122a, 132a of the rims 112, 122, 132. However, if the joint width B is reduced, the electrolyte from the electrolytic layer 105 is more likely to leak to the outside through the joint surfaces 112a, 122a, 132a. For this reason, in order to ensure the ability to prevent leakage, it is not preferable to reduce the joint width B.

[0037] In contrast, in the bipolar storage battery 1 according to the first embodiment, the recesses 160 for ensuring heat dissipation are formed on the outer surfaces of the rims 112, 122, and 132. This allows the joint width B to be large, ensuring the ability to prevent leakage of the electrolyte. In this way, the bipolar storage battery 1 according to the first embodiment can suppress deterioration of charge / discharge characteristics caused by heat retention inside the battery, and can ensure the prevention of electrolyte leakage, thereby achieving both high energy density and long-term reliability. In addition, according to the bipolar storage battery 1 of the first embodiment, the recesses 160 are formed on the outer surfaces of the rims 112, 122, 132, so that the recesses 160 also function as hollow spaces during molding, improving the moldability of the frame units (the internal frame unit 110, the first end frame unit 120, and the second end frame unit 130).

[0038] Second embodiment Next, a bipolar storage battery according to a second embodiment of the present invention will be described with reference to Fig. 3. Fig. 3 is a cross-sectional view showing a schematic configuration of the bipolar storage battery according to the second embodiment of the present invention. The bipolar storage battery 11 shown in FIG. 3 is a bipolar lead-acid battery in which a positive electrode 251 has a positive electrode lead layer 201 and a negative electrode 252 has a negative electrode lead layer 202, and is provided with a plurality of cell members 250, a plurality of internal frame units (frame units) 210, a first end frame unit 220 (frame unit), and a second end frame unit (frame unit) 230. The multiple cell members 250 are stacked and arranged at intervals in the stacking direction (the vertical direction in FIG. 3).

[0039] The multiple inner frame units 210, the first end frame unit 220, and the second end frame unit 230 form multiple cells (spaces) C that individually house multiple cell members 250. Each internal frame unit 210 is composed of a substrate (bipolar plate) 211 having a rectangular planar shape with a positive electrode 251 disposed on one surface and a negative electrode 252 disposed on the other surface, and a rim 212 having, for example, a rectangular frame shape (picture frame shape) provided on the periphery of the substrate 211. The substrate 211 of the internal frame unit 210 is disposed between adjacent cell members 250 in the stacking direction of the cell members 250 (the vertical direction in FIG. 3). The rims 212 of each internal frame unit 210 have joint surfaces 212a that face each other in the stacking direction of the cell members 250 (the vertical direction in FIG. 3).

[0040] The substrate 211 is integrated with the inside of the rim 212. The internal frame unit 210 is made of a thermoplastic resin having sulfuric acid resistance (e.g., polyethylene, polypropylene, polystyrene, polyvinyl chloride, polymethyl methacrylate (acrylic resin), acrylonitrile-butadiene-styrene copolymer (ABS), polyamide (nylon), polycarbonate, etc.). The substrate 211 is located at one end (the lower end in FIG. 3) of the rim 212 in the thickness direction (the vertical direction in FIG. 3). The rim 212 is thicker than the substrate 211. The rim 212 surrounds the side surface of the cell member 250.

[0041] The first end frame unit 220 is composed of a first end plate 221 having a rectangular planar shape and a square frame-shaped (picture frame-shaped) rim 222. The first end plate 221 is integrated with the inside of the rim 222. The first end frame unit 220 is made of a thermoplastic resin having sulfuric acid resistance. The first end frame unit 220 surrounds the side surface and the negative electrode 252 side of the cell member 250 at one end side (the lower end side in FIG. 3 ) of the bipolar storage battery 1. A first end plate 221 surrounds the negative electrode 252 side of the cell member 250, and a rim 222 surrounds the side surface of the cell member 250.

[0042] The first end plate 221 is disposed parallel to the base plate 211 of the internal frame unit 210, and the rim 222 is arranged so as to contact the rim 212 of the adjacent internal frame unit 210. In other words, the rim 122 has a joint surface 222a that faces the rim 212 of the internal frame unit 210 in the stacking direction of the cell members 250 (the up-down direction in FIG. 3). The first end plate 221 has a thickness greater than that of the substrate 211. The rim 222 has a thickness greater than that of the first end plate 221. The first end plate 221 is set to be located at one end (the lower end in FIG. 3) of the rim 222 in the thickness direction (the vertical direction in FIG. 3).

[0043] The second end frame unit 230 is composed of a second end plate 231 having a rectangular planar shape and a rim 232 provided on the outer periphery of the second end plate 231. The second end plate 231 is integrated with the inside of the rim 232. The second end frame unit 230 is made of a thermoplastic resin having sulfuric acid resistance. The second end frame unit 230 surrounds the positive electrode 251 side of the cell member 250 at the other end side of the bipolar storage battery 11 (the upper end side in FIG. 3). The second end plate 231 is disposed parallel to the base plate 211 of the internal frame unit 210, and the rim 232 is arranged so as to contact the rim 212 of the adjacent internal frame unit 210. In other words, the rim 232 has a joining surface 232a that faces the rim 212 of the internal frame unit 210 in the stacking direction of the cell members 250 (the up-down direction in FIG. 3). The second end plate 231 has a thickness that is thicker than the thickness of the base plate 211. The rim 232 has the same thickness as the second end plate 231.

[0044] A positive electrode lead layer 201 is disposed on one surface of the substrate 211. A negative electrode lead layer 202 is disposed on the other surface of the substrate 211. A positive electrode active material layer 203 is disposed on the positive electrode lead layer 201. A negative electrode active material layer 204 is disposed on the negative electrode lead layer 202. Between the opposing positive electrode active material layer 203 and negative electrode active material layer 204, an electrolytic layer 205 made of a glass fiber mat or the like impregnated with an electrolytic solution such as sulfuric acid is disposed.

[0045] A negative electrode lead layer 202 is disposed on the other surface of the first end plate 221. A negative electrode active material layer 204 is disposed on the negative electrode lead layer 202 on the first end plate 221. An electrolytic layer 205 made of a glass fiber mat or the like impregnated with an electrolytic solution such as sulfuric acid is disposed between the negative electrode active material layer 204 on the first end plate 221 and the positive electrode active material layer 203 of the opposing substrate 211. A positive electrode lead layer 201 is disposed on one surface of the second end plate 231. A positive electrode active material layer 203 is disposed on the positive electrode lead layer 201 on the second end plate 231. An electrolytic layer 205 made of a glass fiber mat or the like impregnated with an electrolytic solution such as sulfuric acid is disposed between the positive electrode active material layer 203 on the second end plate 231 and the negative electrode active material layer 204 of the opposing substrate 211.

[0046] The negative lead layer 202 on the first end plate 221 is provided with a negative terminal 208 that is electrically connected to the outside of the first end plate 221. The positive lead layer 201 on the second end plate 231 is provided with a positive terminal 207 that is electrically connected to the outside of the second end plate 231. In other words, the bipolar storage battery 11 according to the second embodiment includes a positive electrode 251 having a positive electrode active material layer 203, a negative electrode 252 having a negative electrode active material layer 204, and a plurality of cell members 250 including an electrolytic layer 205 interposed between the positive electrode 251 and the negative electrode 252, and a plurality of frame units (a plurality of internal frame units 210, a first end frame unit 220, and a second end frame unit 230) that form a plurality of cells C that individually accommodate the plurality of cell members 250.

[0047] The cell members 250 adjacent to each other in the stacking direction are electrically connected in series. Therefore, the substrate 211 interposed between the cell members 250 adjacent to each other in the stacking direction is provided with a means for electrically connecting the positive electrode lead layer 201 and the negative electrode lead layer 202. In addition, the joint surfaces 212a of the rims 212 of adjacent internal frame units 210, the joint surfaces 222a of the rims 222 of adjacent first end frame units 220 and the joint surfaces 212a of the rims 212 of the internal frame units 210, and the joint surfaces 232a of the rims 232 of adjacent second end frame units 230 and the joint surfaces 212a of the rims 212 of the internal frame units 210 are joined by adhesive or vibration welding.

[0048] In the bipolar storage battery 11 configured in this manner, if the heat generated in the positive electrode active material layer 203 and the negative electrode active material layer 204 of the cell member 250 by the battery reaction is not provided with an appropriate transmission path to the outside, the heat will remain inside the battery and the cell member 250 may be damaged by the heat, resulting in a deterioration of the charge / discharge characteristics. For this reason, in the bipolar storage battery 11 according to the second embodiment, a recess 260 that opens to the outer side is formed on the outer side of each frame unit (the inner frame unit 210, the first end frame unit 220). Specifically, the recess 260 that opens to the outer side is formed on the outer side of the rim 212 of each inner frame unit 210 and on the outer side of the rim 222 of the first end frame unit 220.

[0049] Although not shown, four recesses 260 are formed on the outer surface of the rim 212 of each inner frame unit 210 in the frame portion of each of the rims 212 having a square frame shape (picture frame shape). Each recess 260 is formed in an elongated rectangular shape extending in the direction in which the frame portion of the rim 212 extends, and has a length L (not shown), depth D, and width W in the stacking direction, similar to FIG. 1, and is formed so as to leave the four corner portions (not shown) of the square-shaped frame-shaped rim 212. The length L, depth D, and width W in the stacking direction of each recess 260 are appropriately determined taking into consideration the heat dissipation characteristics of the rim 212, mechanical strength, and leakage prevention performance described below.

[0050] In the bipolar storage battery 11 according to the second embodiment, the thickness of the substrate 211 is set to 1 to 10 mm, the height of the rim 212 is set to 5 to 20 mm, the length of the rim 212 is set to 100 to 500 mm, a joint width B described later is set to 1 to 20 mm, the length L of each recess 260 is set to 90 to 490 mm, the width W of each recess 260 in the stacking direction is set to 3 to 16 mm, and the depth D of each recess 260 is set to 0.5 to 15 mm. Each recess 260 is formed so as to leave the four corners of the square frame-shaped rim 212, but it is also possible to form the recesses in the four corners as well so that one recess 260 surrounds the entire circumference of the square frame-shaped rim 212.

[0051] Each of the recesses 260 formed on the outer surface of the rim 222 of the first end frame unit 220 is formed in a rectangular shape that is elongated in the direction in which the frame portion of the rim 222 extends, similar to the recesses 260 of the rim 212, has a predetermined length, depth, and width in the stacking direction, and is formed so as to leave the four corners of the square frame-shaped rim 222. The length, depth, and width in the stacking direction of each recess 260 are determined appropriately taking into consideration the heat dissipation characteristics and mechanical strength of the rim 222, and the liquid leakage prevention performance described later. Furthermore, the recesses 260 of the rim 222 may also be formed at the four corners of the square frame-shaped rim 222 so that one recess 260 surrounds the entire circumference of the square frame-shaped rim 222 .

[0052] In this way, according to the bipolar storage battery 11 according to the second embodiment, the recesses 260 that open to the outer surface are formed on the outer surfaces of some of the frame units (the inner frame units 210 and the first end frame unit 220) among the frame units (the inner frame units 110, the first end frame unit 220, and the second end frame unit 230). This increases the surface area exposed to the outer surfaces of the frame units (the inner frame units 210 and the first end frame unit 220), and the heat generated in the positive electrode active material layer 203 and the negative electrode active material layer 204 of the cell member 250 by the battery reaction can be appropriately dissipated to the outside from the recesses 260 of the frame units (the inner frame units 210 and the first end frame unit 220). This makes it possible to suppress the deterioration of the charge / discharge characteristics caused by the heat staying inside the battery.

[0053] Furthermore, since it is only necessary to form a recess 260 that opens to the outer side on the outer side of the frame unit (the multiple internal frame units 210 and the first end frame unit 220), the configuration for achieving the heat dissipation function can be simplified. Therefore, according to the bipolar storage battery 11 according to the second embodiment, it is possible to provide a bipolar storage battery 11 that can appropriately dissipate heat generated in the cell members 250 to the outside with a simple configuration.

[0054] Furthermore, in the bipolar storage battery 11 according to the second embodiment, each of the multiple frame units (the multiple internal frame units 210, the first end frame unit 220, and the second end frame unit 230) includes rims 212, 222, 232 having joint surfaces 212a, 222a, 232a that face each other in the stacking direction of the cell member 250, and the recesses 260 are formed on the outer surfaces of the rims 212, 222 of some of the frame units (the multiple internal frame units 210 and the first end frame unit 220) among the multiple frame units (the multiple internal frame units 210 and the first end frame unit 220). This increases the surface area exposed on the outer surfaces of the rims 212, 222, and allows heat generated in the positive electrode active material layer 203 and the negative electrode active material layer 204 of the cell member 250 due to the battery reaction to be properly dissipated to the outside from the recesses 260 of the rims 212, 222. This makes it possible to suppress deterioration of the charge / discharge characteristics caused by heat remaining inside the battery. Moreover, since it is only necessary to form the recess 260 that opens to the outside on the outside surfaces of the rims 212, 222, the structure for achieving the heat dissipation function can be simplified.

[0055] Also, in the bipolar storage battery 11 according to the second embodiment, recesses 260 for ensuring heat dissipation are formed on the outer surfaces of the rims 212, 222. This allows the joint width B (see FIG. 3) to be large, ensuring the ability to prevent leakage of the electrolyte. In this manner, in the bipolar storage battery 11 according to the second embodiment, it is possible to suppress the deterioration of the charge / discharge characteristics caused by heat retention inside the battery, and to ensure the performance of preventing leakage of the electrolyte, thereby achieving both high energy density and long-term reliability. Furthermore, in the bipolar storage battery 11 according to the second embodiment, the recesses 260 are formed on the outer surfaces of the rims 212, 222, so that the recesses 260 also function as hollowing out portions during molding, improving the moldability of the frame units (the inner frame unit 110, the first end frame unit 120).

[0056] Third embodiment Next, a bipolar storage battery according to a third embodiment of the present invention will be described with reference to Fig. 4. Fig. 4 is a perspective view of an inner frame unit used in the bipolar storage battery according to the third embodiment of the present invention. The bipolar storage battery according to the third embodiment of the present invention has the same basic configuration as the bipolar storage battery 1 according to the first embodiment shown in FIG. 1, but differs in the configuration of the recesses 160 formed on the outer surface of the rim 112 of each inner frame unit 110, the outer surface of the rim 122 of the first end frame unit 120, and the outer surface of the rim 132 of the second end frame unit 130.

[0057] The recesses 160 formed in the rim 112 of the internal frame unit 110 used in the bipolar storage battery of the third embodiment of the present invention are formed in four portions in each frame portion of the rectangular frame-shaped (picture frame-shaped) rim 112, similar to the recesses 160 in the first embodiment, as shown in FIG. 4 (only two recesses 160 are shown in FIG. 4). Each recess 160, like the recess 160 in the first embodiment, is formed in an elongated rectangular shape extending in the direction in which the frame portion of the rim 112 extends, and has dimensions of length L, depth D, and width W in the stacking direction, and is formed so as to leave the four corner portions 113 of the rim 112 in a square frame shape.

[0058] However, unlike the recess 160 of the first embodiment, the recess 160 of the third embodiment includes a plurality of reinforcing ribs 161 that extend in the stacking direction of the cell members 150 and connect the open ends 160a, 160b of the recess 160. The multiple reinforcing ribs 161 each have a width t and are disposed at a predetermined pitch p along the extending direction of the recess 160. Each reinforcing rib 161 extends from the open end edges 160a, 160b of the recess 160 to the bottom surface.

[0059] Furthermore, the recesses 160 formed on the outer surface of the rim 122 of the first end frame unit 120 and the outer surface of the rim 132 of the second end frame unit 130 are also provided with a plurality of reinforcing ribs (not shown) that extend in the stacking direction of the cell members 150 and connect the open edges of the recesses 160, similar to the recesses 160 formed on the rim 112 of the interior frame unit 110. These reinforcing ribs also each have a width t and are installed at a predetermined pitch p along the direction in which the recesses 160 extend. Each reinforcing rib extends from the open edge of the recess 160 to the bottom surface.

[0060] As described above, in the bipolar storage battery according to the third embodiment of the present invention, the recess 160 is provided with a reinforcing rib 161 that extends in the stacking direction of the cell member 150 and connects the open edges 160a, 160b of the recess 160. This increases the surface area exposed to the outer faces of the rims 112, 122, 132 compared to the recess 160 according to the first embodiment, and allows heat generated in the positive electrode active material layer 103 and the negative electrode active material layer 104 of the cell member 150 due to the battery reaction to be more effectively dissipated to the outside from the recess 160 of the rims 112, 122, 132.

[0061] Furthermore, by providing the recess 160 with a reinforcing rib 161 extending in the stacking direction of the cell member 150 connecting the open edges 160a, 160b of the recess 160, the mechanical strength can be improved when joining the frame units (the internal frame unit 210, the first end frame unit 220, and the second end frame unit 230) at the joining surfaces 112a, 122a, 132a in the stacking direction. In particular, when joining at the joining surfaces 112a, 122a, 132a is performed by vibration welding, the rims 112, 122, 132 are pressed in the stacking direction, so that providing the reinforcing rib 161 extending in the stacking direction of the cell member 150 connecting the open edges of the recess 160 improves the mechanical strength, which is of great practical benefit. The number, arrangement pitch P, and width t of the reinforcing ribs 161 provided in the recess 160 are appropriately determined in consideration of the heat dissipation characteristics and mechanical strength of the ribs 112, 122, and 132.

[0062] In the bipolar storage battery of the third embodiment, the thickness of the substrate 111 is set to 1 to 10 mm, the height h of the rim 112 is set to 5 to 20 mm, the length d of the rim 112 is set to 100 to 500 mm, the joint width B is set to 1 to 20 mm, the length L of each recess 160 is set to 90 to 490 mm, the width W of each recess 160 in the stacking direction is set to 3 to 16 mm, and the depth D of each recess 160 is set to 0.5 to 15 mm. The width t of the reinforcing rib 161 is set to 1 to 10 mm, and the arrangement pitch p of the reinforcing ribs 161 is set to 3 to 50 mm.

[0063] (Fourth embodiment) A bipolar storage battery according to a fourth embodiment of the present invention will be described with reference to FIGS. The bipolar storage battery 300 shown in FIG. 5 is a bipolar lead storage battery in which a positive electrode 351 has a positive electrode lead layer 301 and a negative electrode 352 has a negative electrode lead layer 302, and includes a plurality of (three in this embodiment) cell members 350 and a plurality of frame units (a plurality of (two in this embodiment) bipolar plates 310, a first end plate 331, a second end plate 332, and a plurality of (three in this embodiment) spacers 320) that form a plurality of cells (spaces) C that individually accommodate the plurality of (three in this embodiment) cell members 350.

[0064] A plurality of (three in this embodiment) cell members 350 are stacked at intervals in the stacking direction (the vertical direction in FIG. 5 ). As shown in FIG. 5 , each cell member 350 includes a positive electrode 351 having a positive electrode active material layer 303, a negative electrode 352 having a negative electrode active material layer 304, and an electrolytic layer 305 interposed between the positive electrode 351 and the negative electrode 352. The multiple frame units include multiple (two in this embodiment) bipolar plates 310 arranged between adjacent cell members 350 in the stacking direction, a first end plate 331 arranged at one end (upper end in Figure 5) of the multiple cell members 350 in the stacking direction, a second end plate 332 arranged at the other end (lower end in Figure 5) of the multiple cell members 350 in the stacking direction, and multiple (three in this embodiment) spacers 320 arranged between adjacent bipolar plates 310 in the stacking direction, between the first end plate 331 and the bipolar plate 310, and between the second end plate 332 and the bipolar plate 310.

[0065] The multiple cells C (three in this embodiment) that individually house the multiple cell members 350 (three in this embodiment) are formed by multiple (two in this embodiment) bipolar plates 310, a first end plate 331, a second end plate 332, and multiple spacers (three in this embodiment) 320.

[0066] Each bipolar plate 310 has a rectangular planar shape, a negative electrode 352 is disposed on one surface in the stacking direction (upper surface in FIG. 5), and a positive electrode 351 is disposed on the other surface in the stacking direction (lower surface in FIG. 5). Each bipolar plate 310 is disposed between adjacent cell members 350 in the stacking direction (upper and lower direction in FIG. 5). Each bipolar plate 310 has a joint surface 310a on the outer periphery of the negative electrode 352 on one surface in the stacking direction and on the outer periphery of the positive electrode 351 on the other surface in the stacking direction. The joint surface 310a on one surface side in the stacking direction of the bipolar plate 310 contacts the adjacent spacer 320 on one surface side in the stacking direction of the bipolar plate 310, and the joint surface 310a on the other surface side in the stacking direction of the bipolar plate 310 contacts the adjacent spacer 320 on the other surface side in the stacking direction of the bipolar plate 310. That is, each bipolar plate 310 has two joining surfaces 310a that face two spacers 320 in the stacking direction of the cell members 350. The plate thickness T1 of each bipolar plate 310 is set appropriately.

[0067] Each bipolar plate 310 is made of a sulfuric acid resistant thermoplastic resin (e.g., polyethylene, polypropylene, polystyrene, polyvinyl chloride, polymethyl methacrylate (acrylic resin), acrylonitrile-butadiene-styrene copolymer (ABS), polyamide (nylon), polycarbonate, etc.).

[0068] The first end plate 331 is disposed at one end (the upper end in FIG. 5) of the stacking direction of the multiple cell members 350, and has a rectangular flat plate shape in plan view. The first end plate 331 is made of a thermoplastic resin that is resistant to sulfuric acid. The plate thickness of the first end plate 331 is thicker than the plate thickness T1 of the bipolar plate 310. The first end plate 331 covers the positive electrode 351 of the cell member 350 at one end side (the upper end side in FIG. 5) of the bipolar storage battery 300 in the stacking direction. The first end plate 331 is disposed parallel to the bipolar plate 310, and has a bonding surface 331a on the outer periphery of the other surface in the stacking direction (the lower surface in FIG. 5). This bonding surface 331a is adapted to contact the adjacent spacer 320 on the other surface side in the stacking direction of the first end plate 331. In other words, the first end plate 331 has a bonding surface 331a that faces the spacer 320 in the stacking direction of the cell members 350.

[0069] The second end plate 332 is disposed at the other end (the lower end in FIG. 5) of the stacking direction of the multiple cell members 350, and has a rectangular flat plate shape in plan view. The second end plate 332 is made of a thermoplastic resin that is resistant to sulfuric acid. The plate thickness of the second end plate 332 is thicker than the plate thickness T1 of the bipolar plate 310. The second end plate 332 covers the negative electrode 352 of the cell member 350 at the other end side in the stacking direction of the bipolar storage battery 300 (the lower end side in FIG. 5). The second end plate 332 is disposed parallel to the bipolar plate 310, and has a bonding surface 332a on the outer periphery of one surface in the stacking direction (the upper surface in FIG. 5). This bonding surface 332a is adapted to contact the adjacent spacer 320 on one surface side in the stacking direction of the second end plate 332. In other words, the second end plate 332 has a bonding surface 332a that faces the spacer 320 in the stacking direction of the cell members 350.

[0070] The spacers 320 are disposed between adjacent bipolar plates 310 in the stacking direction, between the first end plate 331 and the bipolar plate 310, and between the second end plate 332 and the bipolar plate 310, respectively. The spacers 320 arranged between adjacent bipolar plates 310 in the stacking direction are formed in a rectangular frame shape so as to surround the side surfaces of the cell members 350. The spacers 320 are made of a thermoplastic resin having sulfuric acid resistance. The plate thickness t1 of the spacers 320 is thicker than the plate thickness T1 of the bipolar plates 310.

[0071] The spacer 320 is disposed parallel to the bipolar plates 310, with one surface in the stacking direction (upper surface in FIG. 5) in contact with the adjacent bipolar plate 310 on one side in the stacking direction. The spacer 320 is disposed such that the other surface in the stacking direction (lower surface in FIG. 5) in contact with the adjacent bipolar plate 310 on the other side in the stacking direction. In other words, the spacer 320 has two joining surfaces 320a that face the two bipolar plates 310 in the stacking direction of the cell members 350. The spacer 320 disposed between the first end plate 331 and the bipolar plate 310 is formed in a rectangular frame shape so as to surround the side surface of the cell member 350. The spacer 320 is made of a thermoplastic resin having sulfuric acid resistance. The plate thickness t1 of the spacer 320 is thicker than the plate thickness T1 of the bipolar plate 310.

[0072] The spacer 320 is disposed parallel to the bipolar plate 310, and one surface in the stacking direction (upper surface in FIG. 5) is disposed so as to contact the adjacent first end plate 331 on one side in the stacking direction. The spacer 320 is disposed so as to contact the adjacent bipolar plate 310 on the other side in the stacking direction (lower surface in FIG. 5). In other words, the spacer 320 has two joining surfaces 320a that face the first end plate 331 and the bipolar plate 310 in the stacking direction of the cell member 350 (up-down direction in FIG. 5).

[0073] Furthermore, the spacer 320 disposed between the second end plate 332 and the bipolar plate 310 is formed in a rectangular frame shape so as to surround the side surface of the cell member 350. The spacer 320 is made of a thermoplastic resin having sulfuric acid resistance. The plate thickness t1 of the spacer 320 is thicker than the plate thickness T1 of the bipolar plate 310. The spacer 320 is disposed parallel to the bipolar plate 310, and one surface in the stacking direction (upper surface in FIG. 5) is disposed so as to contact the adjacent bipolar plate 310 on one side in the stacking direction. The spacer 320 is also disposed so as to contact the other surface in the stacking direction (lower surface in FIG. 5) with the adjacent second end plate 332 on the other side in the stacking direction. In other words, the spacer 320 has two joining surfaces 320a that face the bipolar plate 310 and the second end plate 332 in the stacking direction of the cell member 350 (up-down direction in FIG. 5).

[0074] A negative electrode lead layer 302 is disposed on one surface of the bipolar plate 310 in the stacking direction. A positive electrode lead layer 301 is disposed on the other surface of the bipolar plate 310 in the stacking direction. A negative electrode active material layer 304 is disposed on the negative electrode lead layer 302 to form a negative electrode 352. Meanwhile, a positive electrode active material layer 303 is disposed on the positive electrode lead layer 301 to form a positive electrode 351. Between the opposing positive electrode active material layer 303 and negative electrode active material layer 304, an electrolytic layer 305 made of a glass fiber mat or the like impregnated with an electrolytic solution such as sulfuric acid is disposed.

[0075] A positive electrode lead layer 301 is disposed on the other surface in the stacking direction of the first end plate 331. A positive electrode active material layer 303 is disposed on this positive electrode lead layer 301 on the first end plate 331 to form a positive electrode 351. An electrolytic layer 305 made of a glass fiber mat or the like impregnated with an electrolytic solution such as sulfuric acid is disposed between the positive electrode active material layer 303 on the first end plate 331 and the negative electrode active material layer 304 of the opposing bipolar plate 310. A negative electrode lead layer 302 is disposed on one surface in the stacking direction of the second end plate 332. A negative electrode active material layer 304 is disposed on the negative electrode lead layer 302 on the second end plate 332 to form a negative electrode 352. An electrolytic layer 305 made of a glass fiber mat or the like impregnated with an electrolytic solution such as sulfuric acid is disposed between the negative electrode active material layer 304 on the second end plate 332 and the positive electrode active material layer 303 of the opposing bipolar plate 310. The positive lead layer 301 on the first end plate 331 is provided with a positive terminal 306 that is electrically connected to the outside of the first end plate 331. The negative lead layer 302 on the second end plate 332 is provided with a negative terminal 307 that is electrically connected to the outside of the second end plate 332.

[0076] In other words, the bipolar storage battery 300 of the fourth embodiment includes a positive electrode 351 having a positive electrode active material layer 303, a negative electrode 352 having a negative electrode active material layer 304, and a plurality of (three in this embodiment) cell members 350 including an electrolytic layer 305 interposed between the positive electrode 351 and the negative electrode 352, and a plurality of frame units (a plurality of (two in this embodiment) bipolar plates 310, a first end plate 331, a second end plate 332, and a plurality of (three in this embodiment) spacers 320) that form a plurality of (three in this embodiment) cells (spaces) C that individually accommodate the plurality of (three in this embodiment) cell members 350.

[0077] The multiple frame units include multiple (two in this embodiment) bipolar plates 310 arranged between adjacent cell members 350 in the stacking direction, a pair of end plates (first end plate 331, second end plate 332) arranged at one end and the other end of the multiple (three in this embodiment) cell members 350 in the stacking direction, and multiple (three in this embodiment) spacers 320 arranged between adjacent bipolar plates 310, 310 in the stacking direction, between one end plate (first end plate 331) of the pair of end plates (first end plate 331, second end plate 332) and the bipolar plate 310, and between the other end plate (second end plate 332) of the pair of end plates (first end plate 331, second end plate 332) and the bipolar plate 310.

[0078] The multiple cells C (three in this embodiment) that individually house the multiple cell members 350 (three in this embodiment) are formed by multiple (two in this embodiment) bipolar plates 310, a pair of end plates (a first end plate 331 and a second end plate 332), and multiple (three in this embodiment) spacers 320. The cell members 350 adjacent to each other in the stacking direction are electrically connected in series. Therefore, the bipolar plate 310 interposed between the cell members 350 adjacent to each other in the stacking direction has a means for electrically connecting the positive electrode lead layer 301 and the negative electrode lead layer 302.

[0079] In addition, the bonding surface 331a of the first end plate 331 and the bonding surface 320a of the spacer 320, the bonding surface 310a of the bipolar plate 310 and the bonding surface 320a of the spacer 320, and the bonding surface 332a of the second end plate 332 and the bonding surface 320a of the spacer 320 are bonded by adhesive or vibration welding. In vibration welding, for example, when joining a joining surface 310a of a bipolar plate 310 and a joining surface 320a of a spacer 320, one joining surface 310a is pressed against the other joining surface 320a and vibrated to generate frictional heat and melt the one joining surface 310a and the other joining surface 320a.

[0080] In the bipolar storage battery 300 configured in this manner, unless an appropriate transmission path to the outside is provided for the heat generated in the positive electrode active material layer 303 and the negative electrode active material layer 304 of the cell member 350 due to the battery reaction, the heat will accumulate inside the battery and the cell member 350 may be damaged by the heat, resulting in a deterioration of the charge / discharge characteristics. For this reason, in the bipolar storage battery 300 according to the fourth embodiment, a recess 360 opening to the outer surface 320b is formed in the outer surface 320b of some of the frame units (plurality of (two in this embodiment) bipolar plates 310, a pair of end plates (first end plate 331, second end plate 332), and plural (three in this embodiment) spacers 320) among the plural frame units. Specifically, a recess 360 opening to the outer surface 320b is formed in the outer surface 320b of each of the plural spacers 320.

[0081] The recesses 360 formed in the outer surface 320b of each spacer 320 are four recesses 360 formed in the frame portion of each of the rectangular frame-shaped spacers 320, as shown in FIG. 6 (only two recesses 360 are shown in FIG. 6). Each recess 360 is formed in a rectangular shape that extends elongated in the direction in which the frame portion of the spacer 320 extends, and has dimensions of length l1, depth f1, and width w1 in the stacking direction, and is formed so as to leave the four corner portions 321 of the square-shaped frame-shaped spacer 320. The length l1, depth f1, and width w1 in the stacking direction of each recess 360 are appropriately determined taking into consideration the heat dissipation characteristics, mechanical strength, and leakage prevention performance (described later) of each spacer 320.

[0082] In the bipolar storage battery 300 according to the fourth embodiment, the plate thickness T1 of the bipolar plate 310 is set to 1 mm to 10 mm, the plate thickness t1 of the spacer 320 is set to 5 mm to 30 mm, the length d1 of the spacer 320 is set to 100 mm to 500 mm, the joint width b1 described later is set to 1 mm to 20 mm, the length l1 of each recess 160 is set to 90 mm to 490 mm, the depth f1 of each recess 160 is set to 0.5 mm to 15 mm, and the width w1 of each recess 360 in the stacking direction is set to 3 mm to 25 mm. Each recess 360 is formed so as to leave the four corner portions 321 of the rectangular frame-shaped spacer 320, but it is also possible to form the recess 360 in the four corner portions 321 as well so that one recess 360 surrounds the entire circumference of the rectangular frame-shaped spacer 320.

[0083] In this way, according to the bipolar storage battery 300 of the fourth embodiment, the outer side surfaces 320b of some of the frame units (the plurality of spacers 320 (three in this embodiment)) among the plurality of frame units (the plurality of (two in this embodiment) bipolar plates 310, the pair of end plates (the first end plate 331 and the second end plate 332), and the plurality of (three in this embodiment) spacers 320) are formed with recesses 360 that open to the outer side surfaces 320b. This increases the surface area exposed to the outer side surfaces of the frame units, and allows the heat generated in the positive electrode active material layer 303 and the negative electrode active material layer 304 of the cell member 350 by the battery reaction to be appropriately dissipated to the outside from the recesses 360 of the frame units. This makes it possible to suppress a deterioration in the charge / discharge characteristics caused by heat staying inside the battery.

[0084] Moreover, since it is only necessary to form the recesses 360 that are open to the outer surfaces 320b of some of the frame units, the structure for achieving the heat dissipation function can be simplified. Therefore, according to the bipolar storage battery 300 according to the fourth embodiment, it is possible to provide a bipolar storage battery 300 that can appropriately dissipate heat generated in the cell members 350 to the outside with a simple configuration.

[0085] Furthermore, in the bipolar storage battery 300 according to the fourth embodiment, the multiple frame units include multiple (two in this embodiment) bipolar plates 310 arranged between adjacent cell members 350 in the stacking direction, a first end plate 331 arranged at one end (upper end in FIG. 5) of the multiple cell members 350 in the stacking direction, a second end plate 332 arranged at the other end (lower end in FIG. 5) of the multiple cell members 350 in the stacking direction, and multiple (three in this embodiment) spacers 320 arranged between adjacent bipolar plates 310 in the stacking direction, between the first end plate 331 and the bipolar plate 310, and between the second end plate 332 and the bipolar plate 310. A plurality of cells C (three in this embodiment) that individually accommodate a plurality of cell members 350 (three in this embodiment) are formed by a plurality of bipolar plates 310 (two in this embodiment), a first end plate 331 and a second end plate 332, and a plurality of spacers (three in this embodiment) 320. Each of the plurality of bipolar plates 310 (two in this embodiment), the first end plate 331 and the second end plate 332, and the plurality of spacers 320 (three in this embodiment) has joint surfaces 310a, 331a, 332a, 320a that face each other in the stacking direction of the cell members 350, and a recess 360 is formed on an outer surface 320b of each of the plurality of spacers 320.

[0086] This increases the surface area exposed to the outer surface 320b of each spacer 320, and allows heat generated in the positive electrode active material layer 303 and the negative electrode active material layer 304 of the cell member 350 due to the battery reaction to be appropriately dissipated to the outside through the recess 360 of the spacer 320. This makes it possible to suppress deterioration of the charge / discharge characteristics caused by heat retention inside the battery. Moreover, since it is only necessary to form the recess 360 that opens to the outer surface 320b of the spacer 320, the structure for achieving the heat dissipation function can be simplified.

[0087] Furthermore, in order to improve the ability to dissipate heat generated inside the battery to the outside, it is sufficient to reduce the joint width b1 (see FIGS. 5 and 6) of the joint surface 320a of each spacer 320, the joint surface 131a of the first end plate 331, and the joint surface 332a of the second end plate 332. However, if the joint width b1 is reduced, the electrolyte from the electrolytic layer 105 is more likely to leak out through the joint surfaces 120a, 131a, and 132a. For this reason, in order to ensure the ability to prevent leakage, it is not preferable to reduce the joint width b1. In contrast, in the bipolar storage battery 300 according to the fourth embodiment, the recess 360 for ensuring heat dissipation is formed on the outer surface 320b of the spacer 320. This allows the joint width b1 to be large, thereby ensuring the performance of preventing leakage of the electrolyte.

[0088] In this way, the bipolar storage battery 300 according to the fourth embodiment can suppress deterioration of the charge / discharge characteristics caused by heat retention inside the battery, and can ensure the ability to prevent electrolyte leakage, thereby achieving both high energy density and long-term reliability. Furthermore, according to the bipolar storage battery 300 of the fourth embodiment, the outer surface 320b of each of the plurality of spacers 320 is formed with the recess 360 that opens to the outer surface 320b. Therefore, the recess 360 also functions as a hollow space during molding, and the formability of each spacer 320 can be improved.

[0089] Fifth embodiment Next, a bipolar storage battery according to a fifth embodiment of the present invention will be described with reference to Fig. 7. Fig. 7 is a cross-sectional view showing a schematic configuration of the bipolar storage battery according to the fifth embodiment of the present invention. The bipolar storage battery 400 shown in FIG. 7 includes a plurality of (three in this embodiment) cell components 450 and a plurality of frame units (a plurality of (two in this embodiment) bipolar plates 410, a first end plate 431, a second end plate 432, and a plurality of (three in this embodiment) spacers 420) that form a plurality of cells (spaces) C that individually accommodate the plurality of (three in this embodiment) cell components 450.

[0090] A plurality of (three in this embodiment) cell members 450 are stacked at intervals in the stacking direction (the vertical direction in FIG. 7 ). Each cell member 450 includes a positive electrode 451 having a positive electrode active material layer 403, a negative electrode 452 having a negative electrode active material layer 404, and an electrolytic layer 405 interposed between the positive electrode 451 and the negative electrode 452, as shown in FIG. The multiple frame units include multiple (two in this embodiment) bipolar plates 410 arranged between adjacent cell members 450 in the stacking direction, a first end plate 431 arranged at one end (upper end in Figure 7) of the multiple cell members 450 in the stacking direction, a second end plate 432 arranged at the other end (lower end in Figure 7) of the multiple cell members 450 in the stacking direction, and multiple (three in this embodiment) spacers 420 arranged between adjacent bipolar plates 410 in the stacking direction, between the first end plate 431 and the bipolar plate 410, and between the second end plate 432 and the bipolar plate 410.

[0091] The multiple cells C (three in this embodiment) that individually accommodate the multiple cell members 450 (three in this embodiment) are formed by multiple (two in this embodiment) bipolar plates 410, a first end plate 431, a second end plate 432, and multiple spacers (three in this embodiment) 420.

[0092] Each bipolar plate 410 has a rectangular planar shape, a negative electrode 452 is disposed on one surface in the stacking direction (upper surface in FIG. 7), and a positive electrode 451 is disposed on the other surface in the stacking direction (lower surface in FIG. 7). Each bipolar plate 410 is disposed between adjacent cell members 450 in the stacking direction (upper and lower direction in FIG. 7). Each bipolar plate 410 has a joint surface 410a on the outer periphery of the negative electrode 452 on one surface in the stacking direction and on the outer periphery of the positive electrode 451 on the other surface in the stacking direction. The joint surface 410a on one surface side in the stacking direction of the bipolar plate 410 contacts the adjacent spacer 420 on one surface side in the stacking direction of the bipolar plate 410, and the joint surface 410a on the other surface side in the stacking direction of the bipolar plate 410 contacts the adjacent spacer 420 on the other surface side in the stacking direction of the bipolar plate 410. That is, each bipolar plate 410 has two bonding surfaces 410a that face two spacers 420 in the stacking direction of the cell members 450. The plate thickness T2 of each bipolar plate 410 is appropriately set, but in this embodiment, it is thicker than the plate thickness T1 of the bipolar plate 410 in the first embodiment and is approximately the same thickness as the plate thickness t2 of the spacer 420.

[0093] Each bipolar plate 410 is made of a sulfuric acid resistant thermoplastic resin (e.g., polyethylene, polypropylene, polystyrene, polyvinyl chloride, polymethyl methacrylate (acrylic resin), acrylonitrile-butadiene-styrene copolymer (ABS), polyamide (nylon), polycarbonate, etc.).

[0094] The first end plate 431 is disposed at one end (the upper end in FIG. 7) of the stacking direction of the multiple cell members 450, and has a rectangular flat plate shape in plan view. The first end plate 431 is made of a thermoplastic resin having sulfuric acid resistance. The plate thickness of the first end plate 431 is thicker than the plate thickness T2 of the bipolar plate 410. The first end plate 431 covers the positive electrode 451 of the cell member 450 at one end side (the upper end side in FIG. 7) of the bipolar storage battery 400 in the stacking direction. The first end plate 431 is disposed parallel to the bipolar plate 410, and has a bonding surface 431a on the outer periphery of the other surface in the stacking direction (the lower surface in FIG. 7). This bonding surface 431a is adapted to contact the adjacent spacer 420 on the other surface side in the stacking direction of the first end plate 431. In other words, the first end plate 431 has a bonding surface 431a that faces the spacer 420 in the stacking direction of the cell members 450.

[0095] The second end plate 432 is disposed at the other end (the lower end in FIG. 7) of the stacking direction of the multiple cell members 450, and has a rectangular flat plate shape in plan view. The second end plate 432 is made of a thermoplastic resin that is resistant to sulfuric acid. The plate thickness of the second end plate 432 is thicker than the plate thickness T2 of the bipolar plate 410. The second end plate 432 covers the negative electrode 452 of the cell member 450 at the other end side in the stacking direction of the bipolar storage battery 400 (the lower end side in FIG. 7). The second end plate 432 is disposed parallel to the bipolar plate 410, and has a bonding surface 432a on the outer periphery of one surface in the stacking direction (the upper surface in FIG. 7). This bonding surface 432a is adapted to contact the adjacent spacer 420 on one surface side in the stacking direction of the second end plate 432. In other words, the second end plate 432 has a bonding surface 432a that faces the spacer 420 in the stacking direction of the cell members 450.

[0096] The spacers 420 are disposed between adjacent bipolar plates 410 in the stacking direction, between the first end plate 431 and the bipolar plate 410, and between the second end plate 432 and the bipolar plate 410. The spacer 420 disposed between adjacent bipolar plates 410 in the stacking direction is formed in a rectangular frame shape so as to surround the side surface of the cell member 450. The spacer 420 is made of a thermoplastic resin having sulfuric acid resistance. The plate thickness t2 of the spacer 420 is approximately the same as the plate thickness T2 of the bipolar plate 410.

[0097] The spacer 420 is disposed parallel to the bipolar plates 410, and one surface in the stacking direction (upper surface in FIG. 7) is disposed in contact with the adjacent bipolar plate 410 on one side in the stacking direction. The spacer 420 is disposed in contact with the adjacent bipolar plate 410 on the other side in the stacking direction (lower surface in FIG. 7). In other words, the spacer 420 has two joining surfaces 420a that face the two bipolar plates 410 in the stacking direction of the cell members 450. The spacer 420 disposed between the first end plate 431 and the bipolar plate 410 is formed in a rectangular frame shape so as to surround the side surface of the cell member 450. The spacer 420 is made of a thermoplastic resin having sulfuric acid resistance. The plate thickness t2 of the spacer 420 is approximately the same as the plate thickness T2 of the bipolar plate 410.

[0098] The spacer 420 is disposed parallel to the bipolar plate 410, and one surface in the stacking direction (upper surface in FIG. 7) is disposed so as to contact the adjacent first end plate 431 on one side in the stacking direction. The spacer 420 is disposed so as to contact the adjacent bipolar plate 410 on the other side in the stacking direction (lower surface in FIG. 7). In other words, the spacer 420 has two joining surfaces 420a that face the first end plate 431 and the bipolar plate 410 in the stacking direction of the cell member 450 (up-down direction in FIG. 7).

[0099] Furthermore, the spacer 420 disposed between the second end plate 432 and the bipolar plate 410 is formed in a rectangular frame shape so as to surround the side surface of the cell member 450. The spacer 420 is made of a thermoplastic resin having sulfuric acid resistance. The plate thickness t2 of the spacer 420 is approximately the same as the plate thickness T2 of the bipolar plate 410. The spacer 420 is disposed parallel to the bipolar plate 410, and one surface in the stacking direction (upper surface in FIG. 7) is disposed so as to contact the adjacent bipolar plate 410 on one side in the stacking direction. The spacer 420 is also disposed so as to contact the other surface in the stacking direction (lower surface in FIG. 7) with the adjacent second end plate 432 on the other side in the stacking direction. In other words, the spacer 420 has two joining surfaces 220a that face the bipolar plate 410 and the second end plate 432 in the stacking direction of the cell member 450 (up-down direction in FIG. 7).

[0100] A negative electrode lead layer 402 is disposed on one surface of the bipolar plate 410 in the stacking direction. A positive electrode lead layer 401 is disposed on the other surface of the bipolar plate 410 in the stacking direction. A negative electrode active material layer 404 is disposed on the negative electrode lead layer 402 to form a negative electrode 452. Meanwhile, a positive electrode active material layer 403 is disposed on the positive electrode lead layer 401 to form a positive electrode 451. Between the opposing positive electrode active material layer 403 and negative electrode active material layer 404, an electrolytic layer 405 made of a glass fiber mat or the like impregnated with an electrolytic solution such as sulfuric acid is disposed.

[0101] A positive electrode lead layer 401 is disposed on the other surface in the stacking direction of the first end plate 431. A positive electrode active material layer 403 is disposed on this positive electrode lead layer 401 on the first end plate 431 to form a positive electrode 451. An electrolytic layer 405 made of a glass fiber mat or the like impregnated with an electrolytic solution such as sulfuric acid is disposed between the positive electrode active material layer 403 on the first end plate 431 and the negative electrode active material layer 404 of the opposing bipolar plate 410. A negative electrode lead layer 402 is disposed on one surface in the stacking direction of the second end plate 432. A negative electrode active material layer 404 is disposed on the negative electrode lead layer 402 on the second end plate 432 to form a negative electrode 452. An electrolytic layer 405 made of a glass fiber mat or the like impregnated with an electrolytic solution such as sulfuric acid is disposed between the negative electrode active material layer 404 on the second end plate 432 and the positive electrode active material layer 403 of the opposing bipolar plate 410. The positive lead layer 401 on the first end plate 431 is provided with a positive terminal 406 that is electrically connected to the outside of the first end plate 431. The negative lead layer 402 on the second end plate 432 is provided with a negative terminal 407 that is electrically connected to the outside of the second end plate 432.

[0102] In other words, the bipolar storage battery 400 of the fifth embodiment includes a positive electrode 451 having a positive electrode active material layer 403, a negative electrode 452 having a negative electrode active material layer 404, and a plurality of (three in this embodiment) cell members 450 each including an electrolytic layer 405 interposed between the positive electrode 451 and the negative electrode 452, and a plurality of frame units (a plurality of (two in this embodiment) bipolar plates 410, a first end plate 431, a second end plate 432, and a plurality of (three in this embodiment) spacers 420) that form a plurality of (three in this embodiment) cells (spaces) C that individually accommodate the plurality of (three in this embodiment) cell members 450.

[0103] The multiple frame units include multiple (two in this embodiment) bipolar plates 410 arranged between adjacent cell members 450 in the stacking direction, a pair of end plates (first end plate 431, second end plate 432) arranged at one end and the other end of the multiple (three in this embodiment) cell members 450 in the stacking direction, and multiple (three in this embodiment) spacers 420 arranged between adjacent bipolar plates 410, 410 in the stacking direction, between one end plate (first end plate 431) of the pair of end plates (first end plate 431, second end plate 432) and the bipolar plate 410, and between the other end plate (second end plate 432) of the pair of end plates (first end plate 431, second end plate 432) and the bipolar plate 410.

[0104] The multiple cells C (three in this embodiment) that individually accommodate the multiple cell members 450 (three in this embodiment) are formed by multiple bipolar plates 410 (two in this embodiment), a pair of end plates (a first end plate 431 and a second end plate 432), and multiple spacers 420 (three in this embodiment). The cell members 450 adjacent to each other in the stacking direction are electrically connected in series. Therefore, the bipolar plate 410 interposed between the cell members 450 adjacent to each other in the stacking direction has a means for electrically connecting the positive electrode lead layer 401 and the negative electrode lead layer 402.

[0105] In addition, the bonding surface 431a of the first end plate 431 and the bonding surface 420a of the spacer 420, the bonding surface 410a of the bipolar plate 410 and the bonding surface 420a of the spacer 420, and the bonding surface 432a of the second end plate 432 and the bonding surface 420a of the spacer 420 are bonded by adhesive or vibration welding. In vibration welding, for example, when joining a joining surface 410a of a bipolar plate 410 and a joining surface 420a of a spacer 420, one joining surface 410a is pressed against the other joining surface 420a and vibrated to generate frictional heat and melt the one joining surface 410a and the other joining surface 420a.

[0106] In the bipolar storage battery 400 configured in this manner, if the heat generated in the positive electrode active material layer 403 and the negative electrode active material layer 404 of the cell member 450 by the battery reaction is not provided with an appropriate transmission path to the outside, the heat will remain inside the battery and the cell member 450 may be damaged by the heat, resulting in a deterioration of the charge / discharge characteristics. For this reason, in the bipolar storage battery 400 according to the fifth embodiment, a recess 360 opening to the outer surface 320b is formed in the outer surface 320b of some of the frame units (plurality of (two in this embodiment) bipolar plates 410, a pair of end plates (first end plate 431, second end plate 432), and plural (three in this embodiment) spacers 420). Specifically, a recess 460 opening to the outer surface 420b is formed in the outer surface 420b of each of the plural spacers 420.

[0107] The recesses 460 formed on the outer side surface 420b of each spacer 420 are four recesses 460 formed in the frame portion of each of the rectangular frame-shaped spacers 420, as shown in FIG. 8 (only two recesses 460 are shown in FIG. 8). Each recess 460 is formed in a rectangular shape that extends elongated in the direction in which the frame portion of the spacer 420 extends, and has dimensions of length l2, depth f2, and width w2 in the stacking direction, and is formed so as to leave four corner portions 421 of the square-shaped frame-shaped spacer 420. The length l2, depth f2, and width w2 in the stacking direction of each recess 460 are appropriately determined taking into consideration the heat dissipation characteristics, mechanical strength, and leakage prevention performance (described later) of each spacer 420.

[0108] In the bipolar storage battery 400 according to the fifth embodiment, the plate thickness t2 of the spacer 420 is set to 5 mm to 30 mm, the length d2 of the spacer 420 is set to 100 mm to 500 mm, the joint width b2 described later is set to 1 mm to 20 mm, the length l2 of each recess 460 is set to 90 mm to 490 mm, the depth f2 of each recess 460 is set to 0.5 mm to 15 mm, and the width w2 of each recess 460 in the stacking direction is set to 3 mm to 25 mm. Each recess 460 is formed so as to leave the four corner portions 421 of the rectangular frame-shaped spacer 420, but it is also possible to form the recess 460 in the four corner portions 421 as well so that one recess 460 surrounds the entire circumference of the rectangular frame-shaped spacer 420.

[0109] In this way, according to the bipolar storage battery 400 of the fifth embodiment, the outer side surfaces 420b of some of the frame units (the plurality of (two in this embodiment) bipolar plates 410, the pair of end plates (the first end plate 431 and the second end plate 432), and the plurality of (three in this embodiment) spacers 420) are formed with recesses 460 that open to the outer side surfaces 420b. This increases the surface area exposed to the outer side surfaces of the frame units, and allows the heat generated in the positive electrode active material layer 403 and the negative electrode active material layer 404 of the cell member 450 by the battery reaction to be appropriately dissipated to the outside from the recesses 460 of the frame units. This makes it possible to suppress a decrease in the charge / discharge characteristics caused by heat staying inside the battery.

[0110] Moreover, since it is only necessary to form recesses 460 that are open to outer surfaces 420b on the outer surfaces 420b of some of the frame units, the configuration for achieving the heat dissipation function can be simplified. Therefore, according to the bipolar storage battery 400 according to the fifth embodiment, it is possible to provide a bipolar storage battery 400 that can appropriately dissipate heat generated in the cell members 450 to the outside with a simple configuration.

[0111] Furthermore, in the bipolar storage battery 400 according to the fifth embodiment, the frame units each include a plurality of (two in this embodiment) bipolar plates 410 arranged between adjacent cell members 450 in the stacking direction, a first end plate 431 arranged at one end (upper end in FIG. 7) of the plurality of cell members 450 in the stacking direction, a second end plate 432 arranged at the other end (lower end in FIG. 7) of the plurality of cell members 450 in the stacking direction, and a plurality of (three in this embodiment) spacers 420 arranged between adjacent bipolar plates 410 in the stacking direction, between the first end plate 431 and the bipolar plate 410, and between the second end plate 432 and the bipolar plate 410. A plurality of cells C (three in this embodiment) that individually accommodate a plurality of cell members 450 (three in this embodiment) are formed by a plurality of bipolar plates 410 (two in this embodiment), a first end plate 431 and a second end plate 432, and a plurality of spacers (three in this embodiment) 420. Each of the plurality of bipolar plates 410 (two in this embodiment), the first end plate 431 and the second end plate 432, and the plurality of spacers 420 (three in this embodiment) has joint surfaces 410a, 431a, 432a, 420a that face each other in the stacking direction of the cell members 450, and a recess 460 is formed on an outer surface 420b of each of the plurality of spacers 420.

[0112] This increases the surface area exposed to the outer surface 320b of each spacer 420, and allows heat generated in the positive electrode active material layer 403 and the negative electrode active material layer 404 of the cell member 450 due to the battery reaction to be properly dissipated to the outside through the recess 460 of the spacer 420. This makes it possible to suppress deterioration of the charge / discharge characteristics caused by heat staying inside the battery. Moreover, since it is only necessary to form the recess 460 that opens to the outer surface 420b of the spacer 420, the structure for achieving the heat dissipation function can be simplified.

[0113] Furthermore, in order to improve the ability to dissipate heat generated inside the battery to the outside, it is sufficient to reduce the joint width b2 (see FIG. 8) of the joint surface 420a of each spacer 420, the joint surface 431a of the first end plate 431, and the joint surface 432a of the second end plate 432. However, if the joint width b2 is reduced, the electrolyte from the electrolytic layer 405 is likely to leak out through the joint surfaces 420a, 431a, and 432a. For this reason, in order to ensure the ability to prevent leakage, it is not preferable to reduce the joint width b2.

[0114] In contrast, in the bipolar storage battery 400 according to the fifth embodiment, the recess 460 for ensuring heat dissipation is formed on the outer surface 420b of the spacer 420. This allows the joint width b2 to be large, thereby ensuring the performance of preventing leakage of the electrolyte. In the bipolar storage battery 400 according to the fifth embodiment, the outer surface 410b of each of the plurality of bipolar plates 410 is also formed with a recess 460 that is open to this outer surface 410b. As shown in FIG. 9 (only two recesses 460 are shown in FIG. 9), four recesses 460 are formed on the outer surface 410b of each bipolar plate 410, each of which has a rectangular shape.

[0115] Each recess 460 is formed in a rectangular shape extending elongated in the direction in which the bipolar plate 410 extends, with dimensions of length L2, depth F2, and width W2 in the stacking direction, and is formed so as to leave the four corner portions 411 of the rectangular bipolar plate 410. The length L2, depth F2, and width W2 in the stacking direction of each recess 460 are appropriately determined taking into consideration the heat dissipation characteristics, mechanical strength, and leakage prevention performance described later of each bipolar plate 410.

[0116] In the bipolar storage battery 400 according to the fifth embodiment, the plate thickness T2 of the bipolar plate 410 is set to 5 mm to 30 mm, the length D2 of the bipolar plate 410 is set to 100 mm to 500 mm, the length L2 of each recess 460 is set to 90 mm to 490 mm, the depth F2 of each recess 460 is set to 0.5 mm to 15 mm, and the width W2 of each recess 460 in the stacking direction is set to 3 mm to 25 mm. Each recess 460 is formed so as to leave the four corner portions 411 of the rectangular bipolar plate 410, but it is also possible to form the recesses 460 in the four corner portions 411 as well so that one recess 460 surrounds the entire circumference of the rectangular bipolar plate 410.

[0117] In this way, in the bipolar storage battery 400 according to the fifth embodiment, the recesses 460 that are open to the outer side surface 410b are also formed on the outer side surface 410b of each of the multiple bipolar plates 410. This increases the surface area exposed to the outer side surface 410b of the bipolar plates 410, and allows heat generated in the positive electrode active material layer 403 and the negative electrode active material layer 404 of the cell member 450 to be appropriately dissipated to the outside not only from the recesses 460 of the spacer 420 but also from the recesses 460 of the bipolar plates 410.

[0118] In the bipolar storage battery 400 according to the fifth embodiment, the plate thickness T2 of the bipolar plate 410 is thicker than the plate thickness T1 of the bipolar plate 310 in the bipolar storage battery 300 according to the fourth embodiment, and the mechanical strength of the bipolar storage battery 400 is higher than the mechanical strength of the bipolar storage battery 300. In practice, the plate thickness of the bipolar plate may be increased to improve the mechanical strength of the bipolar storage battery. In this case, in order to improve the heat dissipation effect from the bipolar plate, it is preferable to form a recess 460 that opens to the outer surface 410b on each of the outer surfaces 410b of the multiple bipolar plates 410 as in the bipolar storage battery 400 according to the fifth embodiment.

[0119] In the bipolar storage battery 400 according to the fifth embodiment, the deterioration of the charge / discharge characteristics caused by heat retention inside the battery can also be suppressed, and the performance of preventing electrolyte leakage can be ensured, so that it is possible to achieve both high energy density and long-term reliability. Also in the bipolar storage battery 400 according to the fifth embodiment, the outer surface 420b of each of the plurality of spacers 420 has a recess 460 formed therein that opens to the outer surface 420b. Therefore, the recess 460 also functions as a hollow space during molding, thereby improving the moldability of each spacer 420.

[0120] Sixth embodiment Next, a bipolar storage battery according to a sixth embodiment of the present invention will be described with reference to Fig. 10. Fig. 10 is a perspective view of a spacer used in the bipolar storage battery according to the sixth embodiment of the present invention. The bipolar storage battery according to the sixth embodiment of the present invention has the same basic configuration as the bipolar storage battery 300 according to the fourth embodiment shown in FIG. 5, but differs in the shape of the recesses 360 formed on the outer surfaces 320b of each spacer 320. The recesses 360 formed in each of the plurality of spacers 320 used in the bipolar storage battery according to the sixth embodiment of the present invention are formed in four portions in the frame portion of each of the rectangular frame-shaped spacers 320, similar to the recesses 360 in the fourth embodiment, as shown in FIG. 10 (only two recesses 360 are shown in FIG. 10).

[0121] Each recess 360, like the recess 360 in the fourth embodiment, is formed in an elongated rectangular shape extending in the direction in which the frame portion of the spacer 320 extends, and has dimensions of length l1, depth f1, and width w1 in the stacking direction, so as to leave four corner portions 321 of the square-shaped frame-shaped spacer 320. However, unlike the recess 360 of the fourth embodiment, the recess 360 of the sixth embodiment includes a plurality of reinforcing ribs 361 that extend in the stacking direction of the cell members 350 and connect the open ends 360a, 360b of the recess 360.

[0122] The multiple reinforcing ribs 361 each have a width t and are installed at a predetermined installation pitch p along the extending direction of the recess 360. Each reinforcing rib 361 extends from the open ends 360a, 360b of the recess 360 to the bottom surface. As described above, in the bipolar storage battery according to the sixth embodiment of the present invention, the recess 360 is provided with a reinforcing rib 361 that extends in the stacking direction of the cell member 350 and connects the open edges 360a, 360b of the recess 360. As a result, in the bipolar storage battery according to the sixth embodiment of the present invention, the surface area exposed to the outer side surface 320b of the spacer 320 is increased compared to the recess 360 according to the fourth embodiment, and heat generated in the positive electrode active material layer 303 and the negative electrode active material layer 304 of the cell member 350 due to the battery reaction can be more effectively dissipated to the outside from the recess 360 of the spacer 320.

[0123] Furthermore, by providing the recess 360 with a reinforcing rib 361 extending in the stacking direction of the cell member 350 and connecting the open edges 360a, 360b of the recess 360, the mechanical strength can be improved when the bipolar plate 310, the spacer 320, the first end plate 331, and the second end plate 332 are joined in the stacking direction at the joining surfaces 310a, 320a, 331a, and 332a. In particular, when the joining at the joining surfaces 310a, 320a, 331a, and 332a is performed by vibration welding, the bipolar plate 310, the spacer 320, the first end plate 331, and the second end plate 332 are pressed in the stacking direction, so by providing the reinforcing rib 361 extending in the stacking direction of the cell member 350 and connecting the open edges 360a, 360b of the recess 360, the mechanical strength is improved, which is of great practical benefit.

[0124] The number, pitch p, and width t of the reinforcing ribs 361 provided in the recess 360 are appropriately determined in consideration of the heat dissipation characteristics and mechanical strength of the spacer 320. In the bipolar storage battery according to the sixth embodiment, the plate thickness T1 of the bipolar plate 310 is set to 1 mm to 10 mm, the plate thickness t1 of the spacer 320 is set to 5 mm to 30 mm, the length d1 of the spacer 320 is set to 100 mm to 500 mm, the joint width b1 is set to 1 mm to 20 mm, the length l1 of each recess 360 is set to 90 mm to 490 mm, the depth f1 of each recess 360 is set to 0.5 mm to 15 mm, and the width w1 of each recess 360 in the stacking direction is set to 3 mm to 25 mm. The width t of the reinforcing rib 161 is set to 1 mm to 10 mm, and the arrangement pitch p of the reinforcing ribs 161 is set to 3 mm to 50 mm.

[0125] Although the embodiment of the present invention has been described above, the present invention is not limited to this and various modifications and improvements can be made. For example, in the bipolar storage battery 1 according to the first embodiment, a recess 160 that opens to the outer side is formed on the outer side of all of the multiple frame units (the multiple internal frame units 110, the first end frame unit 120, and the second end frame unit 130). Specifically, the recess 160 that opens to the outer side is formed on the outer side of the rim 112 of all of the internal frame units 110, the outer side of the rim 122 of the first end frame unit 120, and the outer side of the rim 132 of the second end frame unit 130. However, the recess 160 only needs to be formed on the outer surface of at least one of the frame units 110, 120, 130 among the multiple frame units (the multiple internal frame units 110, the first end frame unit 120, and the second end frame unit 130), specifically, on at least one of the outer surface of the rim 112 of the internal frame unit 110, the outer surface of the rim 122 of the first end frame unit 120, and the outer surface of the rim 132 of the second end frame unit 130. The manner in which the recess is formed is the same in the bipolar storage battery 11 according to the second embodiment and the bipolar storage battery according to the third embodiment.

[0126] In this way, the same effect as described above can be obtained by forming a recess 160 that opens to the outer side on the outer surface of at least one of the frame units 110, 120, 130 among the multiple frame units (the multiple internal frame units 110, the first end frame unit 120, and the second end frame unit 130), specifically, on at least one of the outer surface of the rim 112 of the internal frame unit 110, the outer surface of the rim 122 of the first end frame unit 120, and the outer surface of the rim 132 of the second end frame unit 130. In other words, it is possible to provide a bipolar storage battery 1 that can appropriately dissipate heat generated by the cell members 150 to the outside with a simple configuration.

[0127] Moreover, the shape of each recess 160 in the bipolar storage battery 1 according to the first embodiment does not necessarily have to be formed in an elongated rectangular shape extending in the direction in which the frame portions of the rims 112, 122, and 132 extend. The same applies to the shape of each recess 260 in the bipolar storage battery 11 according to the second embodiment and the shape of each recess 160 in the bipolar storage battery according to the third embodiment. The joining method for the joining surfaces 112a, 122a, 132a in the bipolar storage battery 1 according to the first embodiment and the joining method for the joining surfaces 212a, 222a, 232a in the bipolar storage battery 11 according to the second embodiment are not limited to joining by adhesive or vibration welding, and may be joining by other welding processes such as thermal welding using a hot plate or infrared heating, solvent dissolution, etc. The same applies to the joining method for the joining surfaces in the bipolar storage battery according to the first embodiment.

[0128] Moreover, the electrical connection means provided on the substrate 111, 211 in the bipolar storage battery 1, 11 according to the first and second embodiments is not limited to a specific method. For example, it is possible to electrically connect both sides of the substrate by including conductive particles or conductive fibers throughout the substrate. Also, a conductive member that enables electrical conduction can be incorporated into the substrate. The same applies to the electrical connection means provided on the substrate in the bipolar storage battery according to the third embodiment. In the bipolar storage batteries 300, 400 according to the fourth and fifth embodiments, the number of bipolar plates 310, 410 is two and the number of spacers 320, 420 is three, but the present invention is not limited to this and the number of bipolar plates 310, 410 may be one or more and the number of spacers 320, 420 may be two or more. The same applies to the bipolar storage battery according to the sixth embodiment.

[0129] In the bipolar storage battery 300 according to the fourth embodiment, a recess 360 that opens to the outer side surface 320b is formed in the outer side surface 320b of each of the plurality of spacers 320. However, it is sufficient that the recess 360 is formed in the outer side surface 320b of at least one spacer 320 among the plurality of spacers 320. The manner in which the recess is formed is the same in the bipolar storage battery 400 according to the fifth embodiment and the bipolar storage battery according to the sixth embodiment. In the bipolar storage battery 300 according to the fourth embodiment, the recess 360 is not limited to being formed on the outer surface 320b of at least one of the plurality of spacers 320, but may be formed on the outer peripheral surface of the plurality of bipolar plates 310, the first end plate 331, the second end plate 332, and at least one frame unit of the plurality of spacers 320.

[0130] That is, the recess 360 that opens to the outer side may be formed on the outer side of at least one of the frame units 310, 331, 332, 320 among the frame units (the bipolar plates 310, the first end plate 331, the second end plate 332, and the spacers 320). The method of forming the recess is similar to that of the bipolar storage battery according to the sixth embodiment. In this manner, the same effect as described above can be obtained by forming a recess 360 that opens to the outer surface 320b on the outer surface 320b of at least one spacer 320 among the multiple spacers 320. In other words, it is possible to provide a bipolar storage battery 300 that can appropriately dissipate heat generated in the cell members 350 to the outside with a simple configuration. In addition, a similar effect to that described above can be obtained by forming a recess 360 that opens to the outer side on the outer surface of at least one of the multiple frame units 310, 331, 332, 320 (multiple bipolar plates 310, first end plate 331, second end plate 332, and multiple spacers 320).

[0131] Moreover, the shape of each recess 360 in the bipolar storage battery 300 according to the fourth embodiment does not necessarily have to be formed into an elongated rectangular shape extending in the extension direction of the frame portion of the spacer 320. The same applies to the shape of each recess 460 in the bipolar storage battery 400 according to the fifth embodiment and the shape of each recess 360 in the bipolar storage battery according to the sixth embodiment. In the bipolar storage battery 400 according to the fifth embodiment, a recess 460 that opens to the outer side surface 410b is formed in the outer side surface 410b of each of the multiple bipolar plates 410. However, it is sufficient that the recess 460 is formed in the outer side surface 410b of at least one of the one or multiple bipolar plates 410.

[0132] In the bipolar storage battery according to the sixth embodiment, the multiple reinforcing ribs 361 are provided in the recesses 360 formed in each spacer 320. In the bipolar storage battery 400 according to the fifth embodiment, these reinforcing ribs 361 may be formed in a recess 460 formed in at least one of the spacers 420 among the spacers 420. This further increases the surface area exposed to the outer surface 420b of the spacer 420 compared to the recess 460 formed in the spacer 420 according to the fifth embodiment, and heat generated in the positive electrode active material layer 403 and the negative electrode active material layer 404 of the cell member 450 by the battery reaction can be more effectively dissipated to the outside from the recess 460 of the spacer 420. In addition, by providing the reinforcing ribs 361 extending in the stacking direction of the cell member 350 and connecting the open edges of the recess 360 in the recess 460 of the spacer 420, the mechanical strength when the bipolar plate 410, the spacer 420, the first end plate 431, and the second end plate 432 are joined in the stacking direction at their joining surfaces.

[0133] Furthermore, in the bipolar storage battery 400 according to the fifth embodiment, the reinforcing rib 361 may be formed in a recess 460 formed in at least one of the bipolar plates 410 of one or more bipolar plates 410. This further increases the surface area exposed to the outer surface 410b of the bipolar plate 410 compared to the recess 460 formed in the bipolar plate 410 according to the fifth embodiment, and allows heat generated in the positive electrode active material layer 403 and the negative electrode active material layer 404 of the cell member 450 by the battery reaction to be more effectively dissipated to the outside from the recess 460 of the bipolar plate 410. Furthermore, by providing the reinforcing rib 361 in the recess 460 of the bipolar plate 410, the mechanical strength when the bipolar plate 410, the spacer 420, the first end plate 431, and the second end plate 432 are joined in the stacking direction at the joining surfaces can be further improved.

[0134] The joining method for the joining surfaces 310a, 320a, 331a, and 332a in the bipolar storage battery 300 according to the fourth embodiment and the joining method for the joining surfaces 410a, 420a, 431a, and 432a in the bipolar storage battery 400 according to the fifth embodiment are not limited to joining by adhesive or vibration welding, and may be joining by other welding processes such as thermal welding using a hot plate or infrared heating, solvent dissolution, etc. The same applies to the joining method for the joining surfaces in the bipolar storage battery according to the sixth embodiment.

[0135] Moreover, the electrical connection means provided on the bipolar plates 310, 410 in the bipolar storage battery 300 according to the fourth embodiment and the bipolar storage battery 400 according to the fifth embodiment are not limited to a specific method. For example, it is possible to electrically connect both sides of the substrate by including conductive particles or conductive fibers throughout the substrate. Also, a conductive member that enables electrical conduction can be incorporated into the substrate. The same applies to the electrical connection means provided on the bipolar plates in the bipolar storage battery according to the sixth embodiment.

[0136] In addition, the bipolar storage battery 1 according to the first embodiment is a bipolar lead storage battery in which the positive electrode 151 has the positive electrode lead layer 101 and the negative electrode 152 has the negative electrode lead layer 102, but the bipolar storage battery may use a metal other than lead for the positive electrode 151 and the negative electrode 152. This is also true for the bipolar storage battery 11 according to the second embodiment, the bipolar storage battery according to the third embodiment, the bipolar storage battery 300 according to the fourth embodiment, the bipolar storage battery 400 according to the fifth embodiment, and the bipolar storage battery according to the sixth embodiment. [Industrial Applicability]

[0137] The bipolar storage battery according to the present invention has a simple configuration and can appropriately dissipate heat generated in the cell components to the outside, thereby suppressing deterioration of charge / discharge characteristics due to heat retention inside the battery, ensuring prevention of electrolyte leakage, and achieving both high energy density and long-term reliability, and can be extremely beneficially used in various industries. [Explanation of symbols]

[0138] 1,11 Bipolar battery 101,201 Lead layer for positive electrode 102,202 Lead layer for negative electrode 103,203 Active material layer for positive electrode 104,204 Active material layer for negative electrode 105,205 electrolytic layer 107,207 Positive terminal 108,208 Negative terminal 110,210 Internal frame unit 111,211 Substrate (bipolar plate) 112,212 rims 112a,212a joint surface 120,220 First end frame unit 121,221 First end plate 122,222 rims 122a,222a joint surface 130,230 Second end frame unit 131,231 Second end plate 132,232 rims 132a,232a Joint surface 150,250 Cell components 151,251 Positive electrode 152,252 negative electrode 160,260 Recess 161 Reinforcing rib 300,400 Bipolar battery 301,401 Lead layer for positive electrode 302,402 Lead layer for negative electrode 303,403 Active material layer for positive electrode 304,404 Active material layer for negative electrode 305,405 electrolytic layer 306,406 Positive terminal 307,407 Negative terminal 310,410 Bipolar Plates 310a,410a joint surface 310b, 410b outer surface 320,420 Spacer 320a, 420a joint surface 320b,420b outer surface 321,421 Four corners 331,431 First end plate 331a,431a Joint surface 332,432 Second end plate 332a,432a Joint surface 350,450 Cell material 351,451 Positive electrode 352,452 negative electrode 360,460 Recess 361 Reinforcing rib C Cell (space for accommodating cell components)

Claims

1. A bipolar storage battery comprising: a plurality of cell members each including a positive electrode having a positive electrode active material layer, a negative electrode having a negative electrode active material layer, and an electrolytic layer interposed between the positive electrode and the negative electrode; and a plurality of frame units forming a plurality of cells each accommodating the plurality of cell members individually, wherein adjacent cell members are electrically connected in series; a recessed portion that is open to an outer surface of at least one of the plurality of frame units is formed in the outer surface of the frame unit; each of the plurality of frame units includes a rim having a joining surface facing each other in a stacking direction of the cell members; The recess is formed in an outer surface of a rim of at least one frame unit among the plurality of frame units, a reinforcing rib is provided in the recess, the reinforcing rib extending in the stacking direction of the cell members and connecting open edges of the recess.

2. the plurality of frame units include one or a plurality of bipolar plates disposed between the cell members adjacent to each other in the stacking direction, a pair of end plates disposed at one end and the other end of the plurality of cell members in the stacking direction, and a plurality of spacers disposed between the bipolar plates adjacent to each other in the stacking direction, between one end plate of the pair of end plates and the bipolar plate, and between the other end plate of the pair of end plates and the bipolar plate, a plurality of cells each housing the plurality of cell members are formed by the one or more bipolar plates, the pair of end plates, and the plurality of spacers; each of the one or more bipolar plates, the pair of end plates, and the plurality of spacers has a joining surface that faces each other in a stacking direction of the cell members; 2. The bipolar storage battery according to claim 1, wherein the recess is formed in an outer surface of at least one of the plurality of spacers.

3. 3. The bipolar battery of claim 2, wherein the recess is formed in an outer surface of at least one of the one or more bipolar plates.

4. 4. The bipolar storage battery according to claim 2, wherein a reinforcing rib is provided in the recess, extending in the stacking direction of the cell members and connecting the open edges of the recess.

5. 5. The bipolar lead-acid battery according to claim 1, wherein the positive electrode has a positive lead layer and the negative electrode has a negative lead layer.

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