JP7110922B2 - battery module - Google Patents

Description

The present invention relates to battery modules.

A battery module such as a nickel-hydrogen secondary battery or a lithium-ion secondary battery includes a module body. The module body accommodates battery elements including electrodes. A pressure regulating valve is attached to the module body for regulating the internal pressure when the internal pressure rises above a predetermined pressure due to gas generation inside the module body. As an example of the pressure regulating valve, a safety valve device described in Patent Document 1 is known. A pressure regulating valve (safety valve device) described in Patent Document 1 closes a communicating hole communicating with a module body with an elastic member accommodated in a valve chamber. In this case, when the pressure inside the module body rises above the set pressure, the elastic member is elastically deformed, the sealing of the hole by the elastic member is released, and the gas inside the module body is discharged from the exhaust port. On the other hand, when the pressure inside the module main body falls below the set pressure, the communication hole is closed again by the elastic member.

JP-A-7-230799

By the way, in the technique described above, if the compression rate of the elastic member varies when the elastic member is assembled to the valve chamber, the valve opening pressure of the pressure control valve varies. When the member forming the valve chamber is manufactured by injection molding synthetic resin, the member forming the valve chamber may warp due to heat shrinkage. If the member forming the valve chamber is warped, the compression rate of the elastic member will vary depending on the location of the pressure regulating valve, resulting in variation in the valve opening pressure of the pressure regulating valve. Variations in the valve opening pressure of the pressure regulating valve affect the pressure resistance design of other parts. Therefore, it is desired to reduce variations in compression rate of the elastic member.

An object of one aspect of the present invention is to provide a battery module capable of reducing variations in compressibility of elastic members.

A battery module according to one aspect of the present invention includes an electrode stack in which a plurality of bipolar electrodes are stacked, a plurality of internal spaces provided in the electrode stack between adjacent bipolar electrodes, and an electrode stack. A module main body having a frame body arranged to surround and having a plurality of first communication holes respectively communicating with an internal space; A pressure regulating valve having two communication holes, the pressure regulating valve includes a first member having a second communication hole formed thereon, and a first member for blocking an opening of the second communication hole of the first member on the side opposite to the module main body. An elastic member having an end surface and a second end surface located opposite to the first end surface, and a second member integrated with the first member and facing the second end surface of the elastic member, and a different number of elastic members A battery module in which a first member and a second member are integrated.

According to this configuration, the electrode laminate in which the plurality of bipolar electrodes are laminated, the plurality of internal spaces provided in the electrode laminate that exist between the adjacent bipolar electrodes, and the electrode laminate are arranged to surround the electrode laminate. a frame body having a plurality of first communication holes communicating with the internal space; and a plurality of second communication holes attached to the module body and communicating with the plurality of first communication holes. The pressure regulating valve comprises a first member in which a second communication hole is formed; In a battery module having an elastic member having an end face and a second end face located on the opposite side, and a second member integrated with the first member and facing the second end face of the elastic member, the number of first The member and the second member are integrated. If the number of the second members is larger than the number of the first members, the second members divided into a larger number than the first member are integrated corresponding to the warp of the first member, so the elastic member variation in compression rate can be reduced. On the other hand, if the number of the first members is larger than the number of the second members, the first members, which are divided into a larger number than the second members, are less likely to warp. can be reduced.

In this case, a plurality of second members can be integrated with a single first member.

According to this configuration, since the plurality of second members are integrated with the single first member, the second members divided into a larger number than the first member correspond to the warpage of the first member. Since the elastic members are integrated as one, variation in the compressibility of the elastic members can be reduced.

Also, a single second member can be integrated with a plurality of first members.

According to this configuration, since the single second member is integrated with the plurality of first members, warping is less likely to occur in the first member divided into a larger number than the second member, Variation in compressibility of the elastic member can be reduced.

According to the battery module of one aspect of the present invention, variations in compressibility of the elastic member can be reduced.

1 is a schematic cross-sectional view showing a power storage device including battery modules according to a first embodiment; FIG. 1 is a schematic cross-sectional view of a battery module according to a first embodiment; FIG. 1 is a schematic perspective view of a battery module according to a first embodiment; FIG. 1 is an exploded perspective view (including a partial cross section) showing part of a battery module according to a first embodiment; FIG. 1 is an exploded perspective view showing a pressure regulating valve according to a first embodiment; FIG. It is a longitudinal section showing a part of pressure control valve concerning a 1st embodiment. (A) is a longitudinal sectional view showing an example of a method of joining the module body and the pressure regulating valve according to the first embodiment, and (B) is a module body and pressure regulating valve joined together according to the first embodiment. Fig. 3 is a vertical cross-sectional view showing a valve; FIG. 4 is a cross-sectional view showing a state in which a first member of a conventional pressure regulating valve is warped; FIG. 4 is a cross-sectional view showing a state in which the first member of the pressure regulating valve according to the first embodiment is warped; FIG. 5 is a cross-sectional view showing a pressure regulating valve of a battery module according to a second embodiment;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and overlapping descriptions are omitted.

FIG. 1 is a schematic cross-sectional view showing a power storage device including battery modules according to a first embodiment of the present invention. In FIG. 1, a power storage device 1 is used as a battery for vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage device 1 includes a plurality of (three in this embodiment) bipolar batteries 2A as battery modules. The bipolar battery 2A is, for example, a nickel-metal hydride secondary battery. In the following description, unless otherwise specified, the bipolar battery 2A is a nickel-metal hydride secondary battery.

A plurality of bipolar batteries 2A are stacked with metal conductive plates 3 interposed therebetween. The conductive plates 3 are also arranged outside the bipolar batteries 2A positioned at both ends in the stacking direction (Z-axis direction). The bipolar battery 2A and the conductive plate 3 have, for example, a rectangular shape (rectangular shape in plan view) when viewed from the stacking direction. Conductive plate 3 is electrically connected to adjacent bipolar battery 2A. Thereby, a plurality of bipolar batteries 2A are connected in series in the stacking direction.

A positive electrode terminal 4 is connected to the conductive plate 3 located at one end (here, the lower end) in the stacking direction. A negative electrode terminal 5 is connected to the conductive plate 3 located at the other end (upper end in this embodiment) in the stacking direction. The positive terminal 4 and the negative terminal 5 extend in a direction (X-axis direction) perpendicular to the stacking direction. By providing the positive electrode terminal 4 and the negative electrode terminal 5 as described above, the electric storage device 1 can be charged and discharged.

The conductive plate 3 can also function as a heat sink for releasing heat generated in the bipolar battery 2A. The conductive plate 3 is provided with a plurality of gaps 3 a extending in a direction (Y-axis direction) perpendicular to the stacking direction and the extending direction of the positive terminal 4 and the negative terminal 5 . Coolant such as air passes through these gaps 3a, whereby heat from the bipolar battery 2A is efficiently released to the outside.

The power storage device 1 includes a restraining unit 6 that restrains the bipolar battery 2A and the conductive plate 3 in the stacking direction. The restraint unit 6 has a pair of restraint plates 7 that sandwich the bipolar battery 2A and the conductive plate 3 in the stacking direction, and a plurality of sets of bolts 8 and nuts 9 that fasten the restraint plates 7 together.

The restraining plate 7 is made of metal such as iron. An insulating film 10 such as a resin film is arranged between each constraining plate 7 and the conductive plate 3 . The constraining plate 7 and the insulating film 10 are rectangular in plan view, for example. With the shaft portion 8a of the bolt 8 inserted through the insertion hole 7a provided in each restraining plate 7, the nut 9 is screwed onto the tip portion of the shaft portion 8a, whereby the bipolar battery 2A, the conductive plate 3 and the insulating film are assembled. A restraining load is applied to 10 in the stacking direction.

FIG. 2 is a schematic cross-sectional view of a bipolar battery 2A. FIG. 3 is a schematic perspective view of the bipolar battery 2A. 2 and 3, the bipolar battery 2A has a structure (multi-cell structure) in which a plurality of cells (for example, 24 cells) are stacked. The bipolar battery 2A includes a module body 11 and a plurality (four in this embodiment) of pressure control valves 12A attached to one side surface of the module body 11. As shown in FIG.

The module main body 11 includes an electrode laminate 15 in which a plurality of bipolar electrodes 13 are laminated with separators 14 interposed therebetween, and a frame 16 arranged to surround the electrode laminate 15 .

The bipolar electrodes 13 and the separators 14 are rectangular in plan view, for example. The separator 14 is arranged between the bipolar electrodes 13 adjacent to each other in the stacking direction. The bipolar electrode 13 includes a nickel foil 17 as a current collector, a positive electrode active material layer 18 formed on an upper surface 17a (one surface) of the nickel foil 17, and a lower surface 17b (another surface) of the nickel foil 17. and a negative electrode active material layer 19 .

The positive electrode active material layer 18 of the bipolar electrode 13 faces the negative electrode active material layer 19 of one bipolar electrode 13 adjacent in the stacking direction with the separator 14 interposed therebetween. The negative electrode active material layer 19 of the bipolar electrode 13 faces the positive electrode active material layer 18 of the other bipolar electrode 13 adjacent in the stacking direction with the separator 14 interposed therebetween.

A positive terminal electrode 20 is arranged at the bottom layer of the electrode laminate 15 . The positive terminal electrode 20 has a nickel foil 17 and a positive active material layer 18 formed on the upper surface 17 a of the nickel foil 17 . A negative terminal electrode 21 is arranged on the uppermost layer of the electrode laminate 15 . The negative terminal electrode 21 has a nickel foil 17 and a negative active material layer 19 formed on the bottom surface 17b of the nickel foil 17 . The positive electrode active material layer 18 of the positive terminal electrode 20 faces the negative electrode active material layer 19 of the lowermost bipolar electrode 13 with the separator 14 interposed therebetween. The negative electrode active material layer 19 of the negative terminal electrode 21 faces the positive electrode active material layer 18 of the uppermost bipolar electrode 13 with the separator 14 interposed therebetween. The nickel foils 17 of the positive terminal electrode 20 and the negative terminal electrode 21 are connected to adjacent conductive plates 3 (see FIG. 1) in the stacking direction.

The positive electrode active material layer 18 is formed by coating one surface of the nickel foil 17 with a positive electrode slurry containing a positive electrode active material. Nickel hydroxide coated with cobalt (Co) oxide, for example, is used as the positive electrode active material. The negative electrode active material layer 19 is formed by coating the other surface of the nickel foil 17 with a negative electrode slurry containing a negative electrode active material. For example, a hydrogen storage alloy is used as the negative electrode active material. An edge portion 17c of the nickel foil 17 is an uncoated region where the positive electrode slurry and the negative electrode slurry are not coated.

The separator 14 is arranged between the positive electrode active material layer 18 and the negative electrode active material layer 19 to separate the positive electrode active material layer 18 and the negative electrode active material layer 19 . The separator 14 is smaller than the nickel foil 17 and larger than the positive electrode active material layer 18 and the negative electrode active material layer 19 when viewed in the stacking direction. The separator 14 is formed in a sheet shape, for example. The separator 14 is formed of a porous film made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP), or a nonwoven fabric or woven fabric made of PE, PP, methylcellulose, or the like. The separator 14 may be reinforced with a vinylidene fluoride resin compound or the like. The shape of the separator 14 is not limited to a sheet shape, and may be a bag shape.

Each primary seal portion 22 is arranged for each nickel foil 17 along the stacking direction. The primary seal portion 22 is formed in a frame shape. The primary seal portion 22 is joined to the edge portion 17c of the nickel foil 17 by thermal welding.

The nickel foil 17, the positive electrode active material layer 18, the negative electrode active material layer 19, and the primary seal portion 22 cooperate to form an internal space V between the nickel foils 17 adjacent to each other in the stacking direction. In other words, a space surrounded by two adjacent nickel foils 17 in the stacking direction, the positive electrode active material layer 18 of one nickel foil 17, the negative electrode active material layer 19 of the other nickel foil 17, and the primary seal portion 22 is the internal space. is V. Therefore, an internal space V exists between the bipolar electrodes 13 adjacent to each other in the stacking direction. Therefore, the electrode laminate 15 is provided with a plurality of internal spaces V. As shown in FIG. An internal space V including the inside of the separator 14 is filled with an alkaline electrolyte. As the alkaline electrolyte, an alkaline solution containing, for example, a potassium hydroxide aqueous solution is used. The primary seal portion 22 seals the internal space V. As shown in FIG. Each cell of the bipolar battery 2A is composed of two nickel foils 17, a positive electrode active material layer 18, a negative electrode active material layer 19, a separator 14 and a primary sealing portion 22, which cooperate to form an internal space V. there is

The secondary seal portion 23 has, for example, a rectangular tubular shape. The secondary seal portion 23 further seals the internal space V. As shown in FIG. A secondary seal portion 23 is joined to each primary seal portion 22 . The secondary seal portion 23 is formed by, for example, injection molding.

The primary seal portion 22 and the secondary seal portion 23 are made of resin such as polypropylene (PP), polyphenylene sulfide (PPS) or modified polyphenylene ether (modified PPE).

One wall portion 16a that constitutes the frame 16 is provided with a plurality of (four in this embodiment) pressure regulating valve mounting regions 24 to which the pressure regulating valves 12A are mounted. As shown in FIG. 4, each of the pressure regulating valve mounting regions 24 of the primary seal portion 22 is provided with a plurality of (six in this embodiment) communication holes (first communication holes) 25, respectively. The communication holes 25 are arranged in two rows and three stages (two rows in the Y-axis direction and three stages in the Z-axis direction) in each of the pressure regulating valve mounting regions 24 . Therefore, the communication holes 25 are arranged in eight rows and three stages in the wall portion 16a. Each of the communication holes 25 communicates with the internal space V of a different cell. The arrangement state of the communication holes 25 in each of the pressure regulating valve mounting regions 24 is not limited to 2 rows and 3 stages, but unless otherwise specified, an embodiment in which the communication holes 25 are arranged in 2 rows and 3 stages will be described.

As shown in FIG. 4, each of the pressure regulating valve mounting regions 24 of the secondary seal portion 23 has a plurality of (six in this embodiment) communication holes 26 (first communication holes 26) communicating with each of the communication holes 25, respectively. holes) are provided respectively. The communication hole 26 is formed in a tapered shape so that the width gradually increases from the side of the primary seal portion 22 toward the outer surface of the secondary seal portion 23 . The communication holes 26 are arranged in two rows and three stages in each pressure regulating valve mounting region 24 .

The communication holes 25 and 26 function as injection holes for injecting electrolyte into the internal space V. As shown in FIG. The communication holes 25 and 26 serve as channels through which the gas generated in the internal space V flows after the electrolytic solution is injected.

A substantially frame-shaped joining projection 27 is provided on each outer surface of the pressure regulating valve mounting region 24 of the secondary seal portion 23 . The joining projection 27 joins the module main body 11 and the pressure regulating valve 12A, and cooperates with the communication hole 26 to form a plurality of (six in this embodiment) flow paths 28 through which the gas from each internal space V flows. to form. Therefore, the flow passages 28 are arranged in two rows and three stages in each of the pressure regulating valve mounting regions 24 . The flow path 28 has a rectangular cross section taken in a direction perpendicular to the X-axis direction. The flow paths 28 in one row are shifted in the stacking direction (Z-axis direction) with respect to the flow paths 28 in the other row.

The joining projection 27 has a frame portion 29 forming one row of the flow passages 28 and a frame portion 30 forming the other row of the flow passages 28 . Frames 29 and 30 have the same shape and are offset from each other in the Z-axis direction. A gap extending in the Z-axis direction is formed between the frames 29 and 30 .

As shown in FIGS. 4, 5 and 6, the pressure regulating valve 12A includes a single case 33A, a plurality (three in this embodiment) of covers (second members) 34A, and a plurality of (this embodiment of three) covers (second members) 34A. 6) valve bodies (elastic members) 35 .

The case 33A is made of resin such as PP, PPS or modified PPE. The case 33A has a bottom wall (first member) 36A, a case side wall 37, and a partition wall 38, and is open on the side opposite to the bottom wall (first member) 36A. For example, bottom wall 36A, case side wall 37 and partition wall 38 may be integrally formed.

The bottom wall 36A has a bottom surface (first surface) 36a facing the module body 11 and an inner wall surface (second surface) 36b located on the opposite side of the bottom surface 36a. The bottom wall 36A is formed with a plurality of (six in this embodiment) communicating holes (second communicating holes) 39 penetrating between the bottom surface 36a and the inner wall surface 36b. In other words, the plurality of communication holes 39 penetrate through the bottom wall 36A in the thickness direction. These communication holes 39 communicate with the plurality of communication holes 26 of the module body 11 respectively. The communication hole 39 has, for example, a circular cross section taken in a direction perpendicular to the X-axis direction.

As shown in FIGS. 4 and 6, substantially frame-shaped connecting protrusions 40 are provided on the bottom surface 36a. The joining protrusion 40 joins the module main body 11 and the pressure regulating valve 12A, and forms a plurality of (six in this embodiment) flow paths 41 through which gases from the internal spaces V respectively flow. The joining projections 40 are joined to the joining projections 27 of the module body 11 . The bonding projection 40 has a shape and size corresponding to the bonding projection 27 . Therefore, the flow path 41 has, for example, a rectangular cross section taken in a direction perpendicular to the X-axis direction. The channels 41 in one row are shifted in the Z-axis direction with respect to the channels 41 in the other row.

As shown in FIGS. 4, 5 and 6, the case side wall 37 is provided on the inner wall surface 36b side of the bottom wall 36A. The case side wall 37 is, for example, erected on the peripheral edge of the bottom wall 36A. The case side wall 37 is frame-shaped, and the side opposite to the bottom wall 36A of the case side wall 37 is open. Further, as shown in FIG. 5, the case side wall 37 partitions the space formed by the case side wall 37 and the bottom wall 36A into three spaces corresponding to the three covers 34A.

The partition wall 38 partitions each of the three spaces formed by the case side wall 37 and the bottom wall 36A into two housing portions 44 for housing the two valve bodies 35 together with the case side wall 37 and the bottom wall 36A. Therefore, the case 33A has six accommodating portions 44 each accommodating a total of six valve bodies. The housing portion 44 has, for example, a circular cross section taken in a direction perpendicular to the X-axis direction. The plurality of accommodating portions 44 are arranged corresponding to the plurality of communication holes 39 . The accommodation portion 44 can communicate with the corresponding communication hole 39 .

The three covers 34A shown in FIGS. 4, 5 and 6 are made of resin such as PP, PPS or modified PPE. The three covers 34A are joined to the case 33A with their inner wall surfaces 34a so as to close the openings of the three regions each including the two accommodating portions 44 of the case 33A. In other words, in the present embodiment, different numbers of bottom walls 36A and covers 34A are integrated via the case side walls 37 . Specifically, a plurality of (three in this embodiment) covers 34A are integrated with a single bottom wall 36A. The case side wall 37 and the partition wall 38 may be integrally formed with the plurality of covers 34A in advance by injection molding or the like, and may be thermally welded to the bottom wall 36A later.

The cover 34A is bonded to the case 33A by heat welding while being vibrated by ultrasonic waves, for example. As shown in FIGS. 4 and 6, a space S communicating with the housing portion 44 is formed between the partition wall 38 of the case 33A and the cover 34A. In other words, the partition wall 38 is also a wall that forms a plurality of housing portions 44A and the space S in the internal space formed by the bottom wall 36A, the case side wall 37 and the cover 34A. At least one exhaust port (exhaust portion) 45 is formed in the cover 34A. The exhaust port 45 communicates with the space S.

As shown in FIGS. 4, 5 and 6, the plurality of valve bodies 35 are housed in the plurality of housing portions 44, respectively. The valve body 35 opens and closes the corresponding communication hole 39 . The material of the valve body 35 is an elastic body such as rubber. The valve body 35 is columnar. The valve body 35 is, for example, a cylindrical body. The valve body 35 is an injection-molded product of an elastic resin material such as rubber. The valve body 35 has an end face (first end face) 35a and an end face (second end face) 35b in the axial direction C thereof. The end surface 35b is located on the opposite side of the end surface 35a.

The length of the valve body 35 in the axial direction C is longer than the distance between the inner wall surface 36b of the bottom wall 36A and the inner wall surface 34a of the cover 34A. As a result, the end surface 35a is in contact with the inner wall surface 36b, and the end surface 35b is in contact with the inner wall surface 34a. The valve body 35 is pressed against the bottom wall 36A by a cover 34A that is integrated with the bottom wall 36A and faces the end face 35b of the valve body 35A. The end surface 35a closes the opening 39a of the communicating hole 39 of the bottom wall 36A on the side opposite to the module main body 11 . Therefore, the cover 34A also functions as a pressing member for the valve body 35, and the end face 35a of the valve body 35 functions as a sealing surface for closing (sealing) the opening 39a of the communication hole 39. As shown in FIG. A gap G is formed between the outer surface of the valve body 35 and the inner wall surface of the housing portion 44 (the inner wall surface of the case side wall 37 and the partition wall 38 forming the housing portion 44). The size of the cross section perpendicular to the axial direction C of the valve body 35 should be smaller than the size of the cross section perpendicular to the axial direction C of the accommodating portion 44 so that the gap G is formed. Since the accommodation portion 44 communicates with the space S, the gap G communicates with the space S and communicates with the exhaust port 45 via the space S.

In such a pressure regulating valve 12A, the communication hole 39 of the case 33A communicates with the internal space V of the module body 11 through the communication hole 26 of the secondary seal portion 23 and the communication hole 25 of the primary seal portion 22 . When the pressure in the internal space V is lower than the set pressure, the communication hole 39 is kept closed (sealed) by the valve body 35 . When the pressure in the internal space V rises to a set pressure or higher, the valve body 35 is elastically deformed away from the bottom wall 36A, and the communication hole 39 is released from the blockage to open the valve. As a result, the gas from the internal space V passes through the gap G and the space S between the outer surface of the valve body 35 and the inner wall surface of the housing portion 44, and is discharged from the exhaust port 45 to the outside of the pressure regulating valve 12A.

The bipolar battery 2A described above performs a step of joining the module main body 11 and the pressure regulating valve 12A, as shown in FIG. 7A, for example. In this embodiment, the module main body 11 and the pressure regulating valve 12A are joined by hot plate welding, which is one type of thermal welding. Specifically, as shown in FIG. 7A, the module main body 11 and the pressure regulating valve 12A are arranged so that the joining projections 27 and 40 face each other, and the module main body 11 and the pressure regulating valve 12 are arranged. A hot plate 46 is placed between. After that, the tips of the bonding projections 27 and 40 are brought into contact with the hot plate 46 to melt the tips of the bonding projections 27 and 40 . Next, as shown in FIG. 7B, while the joining protrusions 27 and 40 are being melted, the joining protrusion 27 of the module body 11 and the joining protrusion 40 of the pressure regulating valve 12A are pressed together. Thus, the joining protrusions 27 and 40 are welded together. As a result, the joining protrusions 27 and 40 are joined together, and as a result, the module main body 11 and the pressure regulating valve 12A are joined together.

In the present embodiment, an electrode laminate 15 in which a plurality of bipolar electrodes 13 are laminated, a plurality of internal spaces V provided in the electrode laminate 15 that exist between the adjacent bipolar electrodes 13, and the electrode laminate 15 and a frame body 16 having a plurality of communication holes 26 arranged to surround the internal space V and communicating with the internal space V. A pressure regulating valve 12A having a plurality of communication holes 39 is provided. The pressure regulating valve 12A has a bottom wall 36A in which the communication holes 39 are formed, and an opening 39a in the communication hole 39 of the bottom wall 36A on the side opposite to the module main body 11. In a bipolar battery 2A having a valve body 35 having an end face 35a that blocks the end face 35a and an end face 35b located on the opposite side of the end face 35a, and a cover 34A that is integrated with the bottom wall 36A and faces the end face 35b of the valve body 35, Different numbers of bottom walls 36A and covers 34A are integrated. If the number of covers 34A is greater than the number of bottom walls 36A, the covers 34A divided into a larger number than the number of bottom walls 36A are integrated corresponding to the warping of the bottom walls 36A. Variation in compression rate can be reduced. On the other hand, if the number of bottom walls 36A is greater than the number of covers 34A, the bottom walls 36A, which are divided into a larger number than the covers 34A, are less likely to warp. can do.

In addition, in the present embodiment, since a plurality of covers 34A are integrated with a single bottom wall 36A, the cover 34A divided into a larger number than the bottom wall 36A corresponds to the warpage of the bottom wall 36A. Since the valve body 35 is integrated with the valve body 35, variations in the compression rate of the valve body 35 can be reduced.

That is, as exaggeratedly shown in FIG. 8, in the conventional pressure regulating valve 12 in which the bottom wall 36 of one case 33 and one cover 34 are integrated via the case side wall 37, after thermal welding, If the bottom wall 36 warps due to thermal contraction, the compression rate of the valve body 35 varies depending on the location of the pressure regulating valve 12, and the opening pressure of the pressure regulating valve 12 varies. On the other hand, as shown exaggeratedly in FIG. 9, in the pressure regulating valve 12A of the bipolar battery 2A of the present embodiment, a plurality of covers 34A are integrated with a single bottom wall 36A. Even if the cover 34A is warped, the cover 34A, which is divided into a larger number than the bottom wall 36A, follows the warp of the bottom wall 36A and is integrated by welding. can. In addition, as a plurality of valve bodies 35 are provided for one pressure regulating valve 12A, the size of the pressure regulating valve 12A increases and the amount of warpage also increases, so the effect of the present embodiment becomes more effective.

A second embodiment of the present invention will be described below. As shown in FIG. 10, in the pressure regulating valve 12B of the bipolar battery 2B as the battery module of the present embodiment, a plurality (three in the present embodiment) of the case 33B is connected to the bottom wall 36B of the case 33B via the case side wall 37. A single cover 34B is integrated. In the example of FIG. 10, the case side wall 37 and the partition wall 38 are integrally formed with the bottom wall 36B in advance by injection molding or the like. It may be formed integrally with the single cover 34B in advance by injection molding or the like, and may be thermally welded to the bottom wall 36B later.

According to the present embodiment, since the single cover 34B is integrated with the plurality of bottom walls 36B, the bottom walls 36B divided into a larger number than the covers 34B are less likely to warp. Variation in compressibility of body 35 can be reduced. As a plurality of valve bodies 35 are provided for one pressure regulating valve 12B, the size of the pressure regulating valve 12B increases and the amount of warp also increases, so the effect of this embodiment becomes more effective.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments. For example, there are various modes in which bottom walls 36A, 36B and covers 34A, 34B are integrated in different numbers. Any number of bottom walls 36A, 36B and any number of covers 34A, 34B may be used. Further, in the above embodiment, the bipolar batteries 2A and 2B as battery modules are nickel-metal hydride secondary batteries. However, the present invention is not limited to nickel-hydrogen secondary batteries, and can be applied to lithium-ion secondary batteries and the like. In addition to the bipolar batteries 2A and 2B, the present invention is applicable to any battery module having a module main body having an electrode laminate in which a plurality of electrodes are laminated and a frame body arranged so as to surround the electrode laminate. It is possible.

REFERENCE SIGNS LIST 1 power storage device 2A, 2B bipolar battery (battery module) 3 conductive plate 3a gap 4 positive terminal 5 negative terminal 6 restraining unit 7 restraining plate 7a insertion hole DESCRIPTION OF SYMBOLS 8... Bolt, 8a... Shaft part, 9... Nut, 10... Insulating film, 11... Module body, 12, 12A, 12B... Pressure regulating valve, 13... Bipolar electrode, 14... Separator, 15... Electrode laminate, 16... Frame 16a Wall portion 17 Nickel foil 17a Upper surface (one surface) 17b Lower surface (other surface) 17c Edge 18 Positive electrode active material layer 19 Negative electrode active material layer 20 Positive electrode side termination electrode 21 Negative electrode side termination electrode 22 Primary seal portion 23 Secondary seal portion 24 Pressure regulating valve mounting region 25, 26 Communication hole (first communication hole) 27 For joining Projection 28 Flow path 29, 30 Frame 33, 33A, 33B Case 34, 34A, 34B Cover (second member) 34a Inner wall surface 35 Valve body (elastic member) 35a ... end surface (first end surface), 35b ... end surface (second end surface), 36, 36A, 36B ... bottom wall (wall portion, first member), 36a ... bottom surface (first surface), 36b ... inner wall surface (second surface), 37... Case side wall, 38... Partition wall, 39... Communication hole (second communication hole), 39a... Opening, 40... Joining projection, 41... Flow path, 44... Accommodating part, 45... Exhaust port, 46 : hot plate, C: axial direction, G: gap, S: space, V: internal space.

Claims (3)

an electrode laminate in which a plurality of bipolar electrodes are laminated; a plurality of internal spaces existing between the adjacent bipolar electrodes and provided in the electrode laminate; a module main body having a frame body having a plurality of first communication holes each communicating with a space;
a pressure regulating valve attached to the module body and having a plurality of second communication holes respectively communicating with the plurality of first communication holes;
with
The pressure regulating valve is
a first member in which the second communication hole is formed;
an elastic member having a first end surface that blocks an opening of the second communication hole of the first member on the side opposite to the module main body and a second end surface located on the opposite side to the first end surface;
a second member integrated with the first member and facing the second end surface of the elastic member;
has
A battery module in which different numbers of the first members and the second members are integrated. 2. The battery module according to claim 1, wherein a plurality of said second members are integrated with a single said first member. 2. The battery module according to claim 1, wherein a plurality of said first members are integrated with a single said second member.

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