JP7074701B2 - Power storage module and power storage device - Google Patents

Description

The present invention relates to a power storage module and a power storage device.

A power storage module having a bipolar electrode having a positive electrode formed on one surface of an electrode plate and a negative electrode formed on the other surface is known (see Patent Document 1). The power storage module includes a laminated body in which a plurality of bipolar electrodes are laminated via a separator. On the side surface of the laminated body, a sealing body for sealing between the bipolar electrodes adjacent to each other in the stacking direction is provided, and the electrolytic solution is housed in the internal space formed between the bipolar electrodes. Then, such a power storage module is laminated via a cooling plate (conductive plate) to form a power storage device.

Japanese Unexamined Patent Publication No. 2018-101489

In the power storage module as described above, the pressure in the internal space changes due to the causes such as the outside air temperature and the outside pressure. The electrode plate and the metal plate constituting the power storage module are distorted by swelling in one direction or denting in the other in the stacking direction due to the pressure change. Further, the power storage modules are stacked via a conductive plate when they are stacked as a power storage device. Even if the metal plates arranged at both ends of the bipolar electrode group swell toward the outside of the laminated body due to the above pressure change, the swelling is restricted at the portion in contact with the edge portion of the conductive plate. Therefore, the metal plate is distorted between the portion that contacts the edge portion of the conductive plate and the portion that does not contact the edge portion. Since this strain is relatively large as compared with the strain described above, fatigue fracture may occur due to repeated occurrence of such strain. However, if an attempt is made to simply increase the rigidity to prevent fatigue fracture, the thickness of the electrode plate and the metal plate becomes large, which leads to an increase in the size of the power storage module.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a power storage module and a power storage device capable of increasing resistance to fatigue fracture while suppressing an increase in size.

The power storage module according to the present invention includes a group of bipolar electrodes in which a positive electrode active material layer is formed on one surface of an electrode plate and a bipolar electrode having a negative electrode active material layer formed on the other surface is laminated in the first direction. A laminate having a metal plate arranged outside the bipolar electrode group in the first direction, and a sealing body that holds the electrode plate and the peripheral edge of the metal plate and covers the side surfaces of the laminate intersecting in the first direction. The breaking elongation of the metal plate is larger than the breaking elongation of the electrode plate, and the tensile strength of the electrode plate is larger than the tensile strength of the metal plate.

As a result of diligent studies, the inventors of the present application allow the above strain by increasing the breaking elongation of the metal plate instead of increasing the rigidity of the metal plate and suppressing the strain itself caused by the pressure change in the internal space. , Found that fatigue fracture can be prevented. On the other hand, it is known that the tensile strength of a metal plate decreases when the elongation at break is increased. The process of forming the active material layer on both sides of the electrode plate and forming the bipolar electrode includes press molding by a roller or the like. In order to maintain the productivity of the bipolar electrode, the electrode plate is required to have a tensile strength capable of withstanding such a process. On the other hand, the metal plate arranged outside the bipolar electrode group is a terminal electrode in which the active material layer is formed on only one surface, or is uncoated on both sides in which the active material layer is not formed. It is a work metal plate. Therefore, the metal plate is not required to have as high tensile strength as the electrode plate. Therefore, in the power storage module according to the present invention, the electrode plate forming the bipolar electrode has a relatively high tensile strength, and the metal plate has a relatively large breaking elongation. As a result, the productivity when manufacturing the bipolar electrode can be maintained. As a result, it is possible to increase the resistance to fatigue fracture while suppressing the increase in size. The definition and measurement method of breaking elongation and tensile strength referred to here are based on JIS Z2241.

In the power storage module according to the present invention, the breaking elongation of the metal plate may be 10% or more and 35% or less, and the breaking elongation of the electrode plate may be 1% or more and 6% or less. The power storage module having this configuration can more effectively suppress the increase in size and increase the resistance to fatigue fracture.

In the power storage module according to the present invention, the tensile strength of the metal plate may be 320 N / mm ² or more and 460 N / mm ² or less, and the tensile strength of the electrode plate may be 560 N / mm ² or more and 1000 N / mm ² or less. .. The power storage module having this configuration can more effectively suppress the increase in size and increase the resistance to fatigue fracture.

In the power storage module according to the present invention, the sealed body has a frame-shaped side surface portion that covers the side surface of the laminated body and an overhanging portion that extends inward from the end portion of the side surface portion when viewed from the first direction. The peripheral portion of the metal plate may be fixed to the overhanging portion. In this configuration, the portion fixed to the overhanging portion allows the metal plate to be deformed to the outside when the pressure changes, so that the distortion at the edge portion of the conductive plate becomes large. Even with a power storage module having such a configuration, it is possible to increase the resistance to fatigue fracture while suppressing an increase in size.

In the power storage module according to the present invention, the metal plate has a first surface facing the bipolar electrode group and a second surface opposite to the first surface and forming the outermost surface of the laminate. A negative electrode active material layer is formed on the first surface of the metal plate arranged at one end of the bipolar electrode group in the first direction, and the other end of the bipolar electrode group is formed in the first direction. A positive electrode active material may be formed on the first surface of the metal plate arranged in the portion. In this configuration, it can be applied to a power storage module in which a negative electrode terminal electrode and a positive electrode terminal electrode are arranged outside the bipolar electrode group.

In the power storage module according to the present invention, an active material layer is formed on one surface of the electrode plate between the bipolar electrode group and the metal plate arranged at at least one end of the bipolar electrode group, and the other surface is formed. The terminal electrode on which the active material layer is not formed is arranged, and the metal plate arranged adjacent to the terminal electrode may be a metal plate on which the active material layer is not formed on both sides. In this configuration, it can be applied to a power storage module in which an uncoated metal plate is arranged outside the negative electrode terminal electrode. Further, in this configuration, since a space formed by the metal plate can be provided between the internal space and the outside, the progress of alkaline creep can be suppressed.

The power storage module according to the present invention includes the above-mentioned plurality of power storage modules and at least one conductive plate, and the power storage modules may be laminated via the conductive plates. In the power storage device having this configuration, it is possible to increase the resistance to fatigue fracture while suppressing the increase in size.

According to the present invention, it is possible to increase the resistance to a pressure change in the internal space while suppressing the increase in size.

It is a schematic sectional drawing which shows the electric power storage apparatus which is configured with the electric power storage module which concerns on one Embodiment. FIG. 3 is a schematic cross-sectional view showing the internal configuration of the power storage module shown in FIG. 1. It is a graph which showed the relationship between the breaking elongation and the tensile strength in an electrode plate. It is a graph which showed the relationship between the breaking elongation and the number of breaking cycles in an electrode plate. It is a schematic sectional drawing which shows the internal structure of the power storage module which concerns on the modification.

Hereinafter, one embodiment 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 duplicate description is omitted.

The configuration of the power storage device 10 including the power storage module 4 according to the embodiment will be described. The power storage device 10 shown in FIG. 1 is used as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage module 4 is, for example, a bipolar battery. Examples of the power storage module 4 include a nickel hydrogen secondary battery, a secondary battery such as a lithium ion secondary battery, and an electric double layer capacitor. In the following description, a nickel hydrogen secondary battery will be illustrated.

The plurality of power storage modules 4 are laminated via a conductive plate 5 such as a metal plate. Seen from the stacking direction D1 (Z direction), the power storage module 4 and the conductive plate 5 have, for example, a rectangular shape. The conductive plates 5 are also arranged on the outside of the power storage modules 4 located at both ends in the stacking direction D1 of the power storage modules 4. The conductive plate 5 is electrically connected to the adjacent power storage modules 4. As a result, the plurality of power storage modules 4 are connected in series in the stacking direction D1.

In the stacking direction D1, the terminal member 24 is connected to the conductive plate 5 located at one end, and the terminal member 26 is connected to the conductive plate 5 located at the other end. The terminal member 24 may be integrated with the conductive plate 5 to be connected. The terminal member 26 may be integrated with the conductive plate 5 to be connected. The terminal member 24 and the terminal member 26 extend in a direction (X direction) substantially orthogonal to the stacking direction D1. The terminal member 24 and the terminal member 26 can charge and discharge the power storage device 10.

In the power storage device 10, the power storage module 4 may be arranged at one end and the other end in the stacking direction. That is, the outermost layer (stack outermost layer) of the laminate of the electricity storage module 4 and the conductive plate 5 in the electricity storage device 10 may be the electricity storage module 4. In this case, the terminal member 24 and the terminal member 26 are provided for the power storage module 4 on the outermost layer of the stack.

The conductive plate 5 can also function as a heat sink for releasing the heat generated in the power storage module 4. By allowing a refrigerant such as air to pass through the plurality of holes 5a provided inside the conductive plate 5, the heat from the power storage module 4 can be efficiently discharged to the outside. Each hole 5a extends in a direction (Y direction) substantially orthogonal to, for example, the stacking direction D1. The conductive plate 5 is smaller than the power storage module 4 when viewed from the stacking direction D1, but may be the same as or larger than the power storage module 4. As will be described in detail later, the conductive plate 5 is integrally formed as a power storage module 4 described later.

The power storage device 10 includes a restraint member 6 that restrains the alternately stacked power storage modules 4 and the conductive plates 5 in the stacking direction D1. The restraint member 6 includes a pair of restraint plates 6A and 6B and a connecting member (bolt 8 and nut 9) for connecting the restraint plates 6A and 6B to each other. An insulating film 27 such as a resin film is arranged between the restraint plates 6A and 6B and the conductive plate 5. Each of the restraint plates 6A and 6B is made of a metal such as iron. Seen from the stacking direction D1, each of the restraint plates 6A and 6B and the insulating film 27 has, for example, a rectangular shape. The insulating film 27 is larger than the conductive plate 5, and the restraint plates 6A and 6B are larger than the power storage module 4.

When viewed from the stacking direction D1, an insertion hole H1 through which the shaft portion of the bolt 8 is inserted is provided at a position outside the power storage module 4 at the edge portion of the restraint plate 6A. Similarly, when viewed from the stacking direction D1, an insertion hole H2 through which the shaft portion of the bolt 8 is inserted is provided at a position outside the power storage module 4 at the edge portion of the restraint plate 6B. When the restraint plates 6A and 6B have a rectangular shape when viewed from the stacking direction D1, the insertion holes H1 and the insertion holes H2 are located at the corners of the restraint plates 6A and 6B.

One restraint plate 6A is abutted against the conductive plate 5 connected to the terminal member 26 via the insulating film 27, and the other restraint plate 6B has the insulating film 27 attached to the conductive plate 5 connected to the terminal member 24. It is struck through. For example, the bolt 8 is passed through the insertion hole H1 from one restraint plate 6A side toward the other restraint plate 6B side, and a nut 9 is screwed into the tip of the bolt 8 protruding from the other restraint plate 6B. There is. As a result, the insulating film 27, the conductive plate 5, and the power storage module 4 are sandwiched and unitized, and a restraining load is applied to the stacking direction D1. When the outermost layer of the stack is the power storage module 4, the insulating film 27 is interposed between the restraint plates 6A and 6B and the power storage module 4.

Next, the configuration of the power storage module 4 will be described in detail. As shown in FIG. 2, the power storage module 4 includes an electrode laminated body (laminated body) 11 and a resin-made sealing body 12 that seals the electrode laminated body 11. The electrode laminate 11 is composed of a plurality of electrodes laminated along the stacking direction (first direction) D of the power storage module 4 via the separator 13. These electrodes include a laminate of a plurality of bipolar electrodes 14 (bipolar electrode group), a negative electrode termination electrode 18, and a positive electrode termination electrode 19.

The bipolar electrode 14 includes an electrode plate 15 including one surface (first surface) 15a and the other surface (second surface) 15b on the opposite side of the one surface 15a, and a positive electrode layer 16 provided on the one surface 15a. And a negative electrode layer 17 provided on the other surface 15b. The positive electrode layer 16 is a positive electrode active material layer formed by applying a positive electrode active material to the electrode plate 15. The negative electrode layer 17 is a negative electrode active material layer formed by applying a negative electrode active material to the electrode plate 15. In the electrode laminate 11, the positive electrode layer 16 of one bipolar electrode 14 faces the negative electrode layer 17 of another bipolar electrode 14 adjacent to one of the stacking directions D with the separator 13 interposed therebetween. In the electrode laminate 11, the negative electrode layer 17 of one bipolar electrode 14 faces the positive electrode layer 16 of another bipolar electrode 14 adjacent to the other in the stacking direction D with the separator 13 interposed therebetween.

The negative electrode terminal electrode 18 has an electrode plate (metal plate) 15 and a negative electrode layer 17 provided on the other surface 15b of the electrode plate 15. The negative electrode terminal electrode 18 is arranged at one end of the stacking direction D so that the other surface 15b faces the center side of the stacking direction D in the electrode laminated body 11. The negative electrode layer 17 provided on the other surface 15b of the electrode plate 15 of the negative electrode terminal electrode 18 faces the positive electrode layer 16 of the bipolar electrode 14 at one end in the stacking direction D via the separator 13.

The positive electrode terminal electrode 19 has an electrode plate (metal plate) 15 and a positive electrode layer 16 provided on one surface 15a of the electrode plate 15. The positive electrode terminal electrode 19 is arranged at the other end of the stacking direction D so that one surface 15a faces the center side of the stacking direction D in the electrode laminated body 11. The positive electrode layer 16 provided on one surface 15a of the positive electrode terminal electrode 19 faces the negative electrode layer 17 of the bipolar electrode 14 at the other end in the stacking direction D via the separator 13. The other surface 15b of the electrode plate 15 of the positive electrode terminal electrode 19 constitutes the other outer surface in the stacking direction D of the electrode laminate 11, and is electrically connected to the other conductive plate 5 (see FIG. 1) adjacent to the power storage module 4. Is connected.

The electrode plate 15 of the bipolar electrode 14 is, for example, a metal foil made of nickel. The electrode plate 15 of the negative electrode terminal electrode 18 and the positive electrode terminal 19 is, for example, a metal foil made of a nickel-plated steel plate. The peripheral edge portion 15c of the electrode plate 15 has a rectangular frame shape, and is an uncoated region in which the positive electrode active material layer and the negative electrode active material layer are not formed. Examples of the positive electrode active material constituting the positive electrode layer 16 include nickel hydroxide. Examples of the negative electrode active material constituting the negative electrode layer 17 include a hydrogen storage alloy. In the present embodiment, the formation region of the negative electrode layer 17 on the other surface 15b of the electrode plate 15 is slightly larger than the formation region of the positive electrode layer 16 on the one surface 15a of the electrode plate 15.

The separator 13 is formed, for example, in the form of a sheet. The separator 13 is a member that prevents a short circuit between the electrode plates 15 and 15. Examples of the separator 13 include a porous film made of a polyolefin resin such as polyethylene (PE) and polypropylene (PP), a woven fabric made of polypropylene, methyl cellulose and the like, or a non-woven fabric. The separator 13 may be reinforced with a vinylidene fluoride resin compound. The separator 13 is not limited to a sheet shape, and a bag shape may be used.

The sealing body 12 is formed into a rectangular cylinder as a whole by, for example, an insulating resin. The sealing body 12 is provided on the side surface 11a of the electrode laminated body 11 so as to surround the peripheral edge portion 15c of the electrode plate 15. The sealing body 12 holds the peripheral edge portion 15c on the side surface 11a. The sealing body 12 surrounds the plurality of first sealing portions 21 coupled to the peripheral edge portion 15c of the electrode plate 15 and the first sealing portion 21 from the outside along the side surface 11a, and the first sealing portion 21. It has a second sealing portion 22 coupled to each of the above. The first sealing portion 21 and the second sealing portion 22 are, for example, alkaline-resistant insulating resins. Examples of the constituent materials of the first sealing portion 21 and the second sealing portion 22 include polypropylene (PP), polyphenylene sulfide (PPS), modified polyphenylene ether (modified PPE), and the like.

The first sealing portion 21 is continuously provided on one surface 15a of the electrode plate 15 over the entire circumference of the peripheral edge portion 15c, and has a rectangular annular shape when viewed from the stacking direction D. The first sealing portion 21 is welded to one surface 15a of the electrode plate 15 by, for example, ultrasonic waves or heat, and is airtightly bonded. The first sealing portion 21 is, for example, a film having a predetermined thickness in the stacking direction D. The inside of the first sealing portion 21 is located between the peripheral portions 15c of the electrode plates 15 adjacent to each other in the stacking direction D. The outside of the first sealing portion 21 projects outward from the edge of the electrode plate 15, and the tip portion thereof is embedded in the second sealing portion 22. The first sealing portions 21 adjacent to each other along the stacking direction D may be separated from each other or may be in contact with each other.

The second sealing portion 22 is provided on the outside of the electrode laminate 11 and the first sealing portion 21, and constitutes the outer wall (housing) of the power storage module 4. The second sealing portion 22 is formed, for example, by injection molding of a resin, and extends along the stacking direction D over the entire length of the electrode laminate 11. The second sealing portion 22 has a rectangular tubular shape (annular shape) extending with the stacking direction D as the axial direction. The second sealing portion 22 is welded to the outer surface of the first sealing portion 21 by heat during injection molding, for example.

The first sealing portion 21 and the second sealing portion 22 form an internal space V between adjacent electrodes and seal the internal space V. More specifically, the second sealing portion 22, together with the first sealing portion 21, is between the bipolar electrodes 14 adjacent to each other along the stacking direction D, and the negative electrode termination electrodes 18 adjacent to each other along the stacking direction D. And the bipolar electrode 14, and between the positive electrode terminal 19 and the bipolar electrode 14 adjacent to each other along the stacking direction D are sealed. As a result, an airtightly partitioned internal space V is formed between the adjacent bipolar electrodes 14, between the negative electrode termination electrode 18 and the bipolar electrode 14, and between the positive electrode termination electrode 19 and the bipolar electrode 14. ing. An electrolytic solution (not shown) containing an alkaline solution such as an aqueous potassium hydroxide solution is housed in the internal space V. The electrolytic solution is impregnated in the separator 13, the positive electrode layer 16, and the negative electrode layer 17.

The second sealing portion 22 forming the outer surface of the sealing body 12 has a side surface portion 22a covering the side surface of the first sealing portion 21 and the side surface portion 22a inward in a plan view from the stacking direction D. It has an extending overhanging portion 22b. The electrode plate 15 of the negative electrode terminal electrode 18 and the positive electrode terminal 19 is welded to the overhanging portion 22b.

Next, the difference in characteristics between the electrode plate 15 of the bipolar electrode 14 and the electrode plates 15 of the negative electrode terminal 18 and the positive electrode 19 will be described in detail. In the present embodiment, the breaking elongation of the electrode plate 15 of the negative electrode terminal 18 and the positive electrode 19 is larger than the breaking elongation of the electrode plate 15 of the bipolar electrode 14. Further, the tensile strength of the electrode plate 15 of the bipolar electrode 14 is larger than the tensile strength of the electrode plate 15 of the negative electrode terminal electrode 18 and the positive electrode terminal 19. The definition and measurement method of breaking elongation and tensile strength referred to here conform to the JIS Z2241 standard.

More specifically, the breaking elongation of the electrode plate 15 of the negative electrode terminal 18 and the positive electrode 19 is 10% or more and 35% or less, and the breaking elongation of the electrode plate 15 of the bipolar electrode 14 is 1% or more and 6% or less. .. Further, the tensile strength of the electrode plate 15 of the negative electrode terminal 18 and the positive electrode 19 is 320 N / mm ² or more and 460 N / mm ² or less, and the tensile strength of the electrode plate 15 of the bipolar electrode 14 is 560 N / mm ² or more. It is 1000 N / mm ² or less.

The inventors of the present application conducted the following experiments in setting an appropriate range of breaking elongation and tensile strength. That is, the inventors of the present application prepared a plurality of types of nickel steel sheets shown in Table 1 below, which differ in breaking elongation and tensile strength. Then, the relationship between the breaking elongation and the tensile strength of the nickel steel sheet foil was estimated. The result of this estimation is shown in the graph shown in FIG.

Next, the number of fracture cycles was measured for each nickel steel sheet foil. Specifically, a bipolar electrode 14, a negative electrode terminal electrode 18, and a positive electrode terminal 19 using each of the above nickel steel plate foils 1 to 4 as the electrode plate 15 are prepared, and a power storage module as shown in FIG. 2 is prepared. 4 was manufactured. Then, a power storage device to be inspected was obtained as shown in FIG. Then, by repeatedly changing the external pressure between 0 MPa and 0.5 MPa in an environment of 45 ° C., each nickel steel sheet foil is repeatedly distorted, and the number of repetitions (number of cycles) until the electrode plate 15 breaks. ) Was measured. The measurement results are as shown in Table 1 above. After confirming that the number of cycles of the nickel steel sheet foil 4 was equal to or greater than that of the nickel steel sheet foil 3, the measurement was discontinued because it took time. From these measured values, the relationship between the elongation at break and the number of cycles at break in the nickel steel sheet foil was estimated. The result of this estimation is shown in the graph shown in FIG.

Here, the inventors of the present application calculated the breaking elongation at that time, assuming that the number of breaking cycles required for the electrode plate 15 of the negative electrode ending electrode 18 and the positive electrode ending electrode 19 is 100,000 times. As a result, the lower limit of the breaking elongation of the negative electrode terminal electrode 18 and the positive electrode terminal 19 was set to 10%. Further, in the case of manufacturing an electrode in which an active material layer is formed on one surface of a nickel steel plate foil as a negative electrode terminal electrode 18 and a positive electrode terminal 19, tensile strength for maintaining productivity in a pressing process or the like is obtained. Is required. The upper limit of the elongation at break is set to 35% from such a viewpoint.

Similarly, the electrode plate 15 of the bipolar electrode 14 is not required to stretch as much as the electrode plate 15 of the negative electrode terminal 18 and the positive electrode 19 while the active material layer is formed on both sides of the nickel steel plate foil as the bipolar electrode 14. When manufacturing a state electrode, tensile strength is required to maintain productivity in the pressing process and the like. Therefore, in the electrode plate 15 of the bipolar electrode 14, the tensile strength is preferentially set from such a viewpoint, and the breaking elongation is set to a value corresponding to these tensile strengths. From this point of view, the electrode plate 15 of the bipolar electrode 14 is set to 560 N / mm ² or more and 1000 N / mm ² or less.

Next, the operation and effect of the power storage module 4 and the power storage device 10 of the above embodiment will be described. In the power storage module 4 as shown in FIG. 2, the pressure in the internal space V changes due to the causes such as the outside air temperature and the outside pressure. The electrode plate 15 constituting the power storage module 4 is distorted by swelling in one direction or denting in the other in the stacking direction due to the pressure change. Further, the power storage modules 4 are stacked via the conductive plate 5 when they are stacked as the power storage device 10 (see FIG. 1).
Even if the negative electrode termination electrodes 18 and the electrode plates 15 of the positive electrode termination electrodes 19 arranged at both ends of the bipolar electrode group swell toward the outside of the electrode laminate 11 due to the above pressure change, the negative electrode termination electrodes 18 and the positive electrode termination electrodes The bulge of the portion of 19 in contact with the edge portion of the electrode plate 15 is restricted. Therefore, the electrode plate 15 of the negative electrode terminal 18 and the positive electrode 19 will be distorted between the portion of the conductive plate 5 that contacts the edge portion P and the portion that does not contact the edge portion P. Since this strain is relatively large as compared with the strain described above, fatigue fracture may occur due to repeated occurrence of such strain. However, if it is simply attempted to increase the rigidity to prevent fatigue fracture, the thickness of the electrode plate 15 of the negative electrode terminal electrode 18 and the positive electrode terminal 19 becomes large, which leads to an increase in the size of the power storage module 4 and thus the power storage device 10.

In the present embodiment, the negative electrode termination electrodes 18 and the electrode plates 15 of the positive electrode termination electrodes 19 arranged at both ends of the bipolar electrode group are allowed to be distorted by increasing the breaking elongation of the electrode plates 15. , Prevents fatigue failure. On the other hand, the tensile strength is increased with respect to the electrode plate 15 of the bipolar electrode 14 which is required to have a tensile strength capable of withstanding press molding in the production process of the bipolar electrode 14. Since the active material layer is formed only on one surface of the negative electrode terminal 18 and the electrode plate 15 of the positive electrode 19 arranged at both ends of the bipolar electrode group, the tension is as high as that of the electrode plate 15 of the bipolar electrode 14. No strength is required. In consideration of such circumstances, in the power storage module 4 of the above embodiment, the electrode plate 15 forming the bipolar electrode 14 has a relatively high tensile strength, and the electrode plate 15 of the negative electrode terminal 18 and the positive electrode 19 is obtained. Has a relatively large breaking elongation. This makes it possible to increase the resistance to fatigue fracture while maintaining the productivity when manufacturing the bipolar electrode 14. As a result, it is possible to increase the resistance to fatigue fracture while suppressing an increase in the size of the power storage module 4 and thus the power storage device 10.

In the power storage module 4 of the above embodiment, the portion of the electrode plate 15 fixed to the overhanging portion 22b allows the electrode plate 15 to be deformed to the outside when the pressure changes, so that the edge portion P of the conductive plate 5 The distortion increases. As described above, even in the power storage module 4 in which the strain at the edge portion P of the conductive plate 5 becomes large, it is possible to increase the resistance to fatigue fracture while suppressing the increase in size.

In the power storage module 4 of the above embodiment, a nickel steel plate foil is used as the electrode plate 15 of the negative electrode terminal 18 and the positive electrode terminal 19, and a nickel foil is used as the electrode plate 15 of the bipolar electrode 14. Unlike the nickel foil, the nickel steel sheet foil is oriented in a direction in which the crystal grain boundaries are orthogonal to the thickness direction of the foil. Therefore, the electrode plate 15 of the negative electrode terminal 18 and the positive electrode 19 is less likely to crack and has resistance to fatigue fracture.

Although one embodiment has been described in detail above, the present invention is not limited to the above embodiment. For example, as shown in FIG. 5, a power storage module having an uncoated metal plate 25 arranged on the outside of the electrode plate 15 of the negative electrode terminal 18 (both sides of which the active material layer is not formed) is arranged. The present invention may be applied to 4A. An example of the metal plate 25 is a nickel steel plate foil. That is, in the power storage module 4A having such a configuration, the breaking elongation of the metal plate 25 and the electrode plate 15 of the positive electrode terminal 19 is larger than the breaking elongation of the electrode plate 15 of the bipolar electrode 14, and the electrode plate 15 of the bipolar electrode 14 The tensile strength of the metal plate 25 and the positive electrode terminal electrode 19 may be larger than the tensile strength of the electrode plate 15. That is, in the power storage module 4A according to the modified example, the breaking elongation of the metal plate 25 in contact with the conductive plate 5 is relatively large.

Also in the power storage module 4A according to the modified example, it is possible to increase the resistance to fatigue fracture while suppressing the increase in the size of the power storage module 4A.

Further, in the power storage module 4A, an extra space VA surrounded by the first sealing portion 21, the electrode plate 15 of the negative electrode terminal electrode 18, and the metal plate 25 is formed. Since the surplus space VA is formed in a portion that can be a passage between the external space and the internal space V, it is possible to suppress the infiltration of moisture from the external space into the internal space V. This makes it possible to suppress the progress of the alkaline creep phenomenon.

4,4A ... Power storage module, 5 ... Conductive plate, 10 ... Power storage device, 11 ... Electrode laminate (laminate), 14 ... Bipolar electrode, 15 ... Electrode plate, 18 ... Negative electrode terminal electrode, 19 ... Positive electrode terminal electrode, 21 ... first sealing portion, 22 ... second sealing portion, 22a ... side surface portion, 22b ... overhanging portion, 25 ... metal plate, P ... edge portion, V ... internal space.

Claims (7)

A group of bipolar electrodes in which a positive electrode active material layer is formed on one surface of an electrode plate and a bipolar electrode having a negative electrode active material layer formed on the other surface are laminated in the first direction, and the bipolar electrode in the first direction. A laminate having a metal plate arranged outside the group, and
A sealing body that holds the peripheral portion of the electrode plate and the metal plate and covers the side surface of the laminated body that intersects in the first direction is provided.
A power storage module in which the breaking elongation of the metal plate is larger than the breaking elongation of the electrode plate, and the tensile strength of the electrode plate is larger than the tensile strength of the metal plate. The power storage module according to claim 1, wherein the metal plate has a breaking elongation of 10% or more and 35% or less, and the electrode plate has a breaking elongation of 1% or more and 6% or less. The storage capacity according to claim 1 or 2, wherein the tensile strength of the metal plate is 320 N / mm ² or more and 460 N / mm ² or less, and the tensile strength of the electrode plate is 560 N / mm ² or more and 1000 N / mm ² or less. module. The sealing body includes a frame-shaped side surface portion that covers the side surface of the laminated body, and an overhanging portion that extends inward from the end portion of the side surface portion when viewed from the first direction.
The power storage module according to any one of claims 1 to 3, wherein the metal plate has a peripheral portion fixed to the overhanging portion. The metal plate has a first surface facing the bipolar electrode group and a second surface opposite to the first surface and forming the outermost surface of the laminate.
A negative electrode active material layer is formed on the first surface of the metal plate arranged at one end of the bipolar electrode group in the first direction.
The invention according to any one of claims 1 to 4, wherein a positive electrode active material is formed on the first surface of the metal plate arranged at the other end of the bipolar electrode group in the first direction. Power storage module. An active material layer is formed on one surface of the electrode plate and an active material layer is formed on the other surface between the bipolar electrode group and the metal plate arranged at at least one end of the bipolar electrode group. The unformed termination electrode is placed and
The power storage module according to any one of claims 1 to 4, wherein the metal plate arranged adjacent to the terminal electrode is a metal plate on which no active material layer is formed on both sides. The plurality of power storage modules according to any one of claims 1 to 6 and the storage module.
With at least one conductive plate,
The power storage module is a power storage device laminated via the conductive plate.

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