Bipolar electrode, bipolar battery, and method for manufacturing bipolar electrode

Abstract

A bipolar electrode (11) is provided with a first active material layer (132), a first current collector (131), an intermediate conductor (12), a second current collector (141), and a second active material layer (142) laminated in this order in a lamination direction, the first active material layer (132) being provided on a first surface (131a) of the first current collector (131), the second active material layer (142) being provided on a second main surface (141b) of the second current collector (141), the second surface (131b) of the first current collector (131) being joined to a surface (12a) of the intermediate conductor (12), and the second surface (131b) of the second current collector (141) being joined to a surface (12a) of the intermediate conductor (12). The first surface (141a) of the second current collector (141) is bonded to the rear surface (12b) of the intermediate conductor (12), the second active material layer (142) is located inside the first active material layer (131) when viewed from the lamination direction, and the length of the intermediate conductor (12) is longer than the length of the first current collector (131) and the length of the second current collector (141) in the longitudinal direction.

Description

Technical Field

[0001] The present disclosure relates to a bipolar electrode, a bipolar battery, and a method for manufacturing the bipolar electrode. Background Art

[0002] As a previous bipolar electrode, for example, Japanese Patent Gazette No. 2005-317468 (Patent Document 1) discloses a structure comprising: a positive electrode collector, which is stamped with a positive electrode active material layer formed on one side, and the positive electrode active material layer is compressed to a desired thickness; and a negative electrode collector, which is stamped with a negative electrode active material layer formed on one side, and the negative electrode active material layer is compressed to a desired thickness, and the positive electrode collector has a surface on which the positive electrode active material layer is not formed and the negative electrode collector has a surface on which the negative electrode active material layer is not formed, connected by a conductive adhesive layer in a state where the surface faces each other.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2005-317468 Summary of the invention

[0006] In Patent Document 1, the positive electrode active material layer and the negative electrode active material layer are formed to have the same width, and similarly, the positive electrode current collector and the negative electrode current collector are formed to have the same width in a size larger than the positive electrode active material layer and the negative electrode active material layer.

[0007] In this case, depending on the positioning accuracy, a portion of the positive electrode active material layer that is not facing the negative electrode active material layer occurs. It is known that when the negative electrode active material layer cannot completely absorb cations (such as lithium ions) released from the positive electrode active material layer, dendrites are generated. The generation of dendrites may cause a micro short circuit, so the battery performance may be reduced.

[0008] In order to suppress such a small short circuit and fully ensure the cation receiving capacity of the negative electrode active material layer, the positive electrode active material layer is set smaller in a manner so that the positive electrode active material layer does not protrude from the negative electrode active material layer when viewed from the stacking direction. However, in the case of simply reducing the positive electrode active material layer, when the conductive adhesive layer is interposed between the surface of the positive electrode collector where the positive electrode active material layer is not formed and the surface of the negative electrode collector where the negative electrode active material layer is not formed and stamping is performed in the stacking direction, it is difficult to press the portion exposed to the outside from the positive electrode active material layer when viewed from the stacking direction.

[0009] Therefore, in the portion exposed to the outside from the positive electrode active material layer when viewed in the stacking direction, bubbles cannot be extracted from the conductive adhesive layer, and there is a possibility that a conduction failure may occur.

[0010] The present disclosure has been made in view of the above-mentioned problems, and an object of the present disclosure is to provide a bipolar electrode, a bipolar battery, and a method for manufacturing a bipolar electrode that can suppress a decrease in battery performance and conduction failure.

[0011] The bipolar electrode based on the present disclosure comprises a first active material layer, a first current collector, an intermediate conductor, a second current collector and a second active material layer stacked in sequence in a stacking direction. The intermediate conductor has a surface located on one side of the stacking direction and a back surface located on the other side of the stacking direction. The first current collector has a first surface located on the one side of the stacking direction and a second surface located on the other side of the stacking direction. The second current collector has a first main surface located on the one side of the stacking direction and a second main surface located on the other side of the stacking direction. The first active material layer is disposed on the first surface of the first current collector. The second active material layer is disposed on the second main surface of the second current collector. The second surface of the first current collector is bonded to the surface of the intermediate conductor. The first main surface of the second current collector is bonded to the back surface of the intermediate conductor. In a length direction orthogonal to the stacking direction, the length of the first active material layer is longer than the length of the second active material layer. The second active material layer is located inside the first active material layer when viewed from the stacking direction. In the length direction, the length of the intermediate conductor is longer than the lengths of the first current collector and the second current collector.

[0012] According to the above structure, the length of the first active material layer is longer than that of the second active material layer, and the formation of a region not facing the first active material layer in the second active material layer when viewed from the stacking direction can be suppressed. Thus, the reduction in battery performance can be suppressed.

[0013] Furthermore, the first current collector provided with the first active material layer and the second current collector provided with the second active material layer can be independently bonded to the surface and back of the intermediate conductor, respectively, so that the bonding state between the second surface of the first current collector and the surface of the intermediate conductor and the bonding state between the first main surface of the second current collector and the back of the intermediate conductor can be stabilized. As a result, poor conduction can be suppressed.

[0014] Furthermore, since the length of the intermediate conductor is longer than the lengths of the first current collector and the second current collector, it is possible to suppress the first current collector and the second current collector from protruding from the intermediate conductor when the first current collector and the second current collector are joined to the intermediate conductor.

[0015] In the bipolar electrode according to the present disclosure, the density of the first active material layer may be smaller than the density of the second active material layer.

[0016] According to the above structure, the first active material layer and the second active material layer can be provided at a density suitable for battery performance, and desired battery performance can be obtained.

[0017] In the bipolar electrode according to the present disclosure, the length of the first current collector may be longer than the length of the second current collector in the longitudinal direction.

[0018] According to the above configuration, by providing the first active material layer on the first current collector which is longer than the second current collector, the first active material layer which is longer than the second active material layer can be reliably formed.

[0019] The bipolar electrode according to the present disclosure may include: a first conductive adhesive layer bonding the second surface of the first current collector and the surface of the intermediate conductor; and a second conductive adhesive layer bonding the first main surface of the second current collector and the back surface of the intermediate conductor.

[0020] According to the above configuration, by using the first conductive adhesive layer and the second conductive adhesive layer, the first current collector and the second current collector can be substantially uniformly joined to the intermediate conductor while suppressing an increase in thickness.

[0021] In the bipolar electrode according to the present disclosure, the first conductive adhesive layer and the second conductive adhesive layer may include conductive particles obtained by coating resin powder with a metal.

[0022] According to the above configuration, since the resin powder is metal-coated, the cost can be reduced compared to the case of using metal particles, and the first current collector and the second current collector can be joined to the intermediate conductor while ensuring a considerable degree of elasticity.

[0023] In the bipolar electrode according to the present disclosure, the thickness of the first conductive adhesive layer and the second conductive adhesive layer parallel to the stacking direction may be approximately the same as the particle diameter of the conductive particles.

[0024] According to the above configuration, by reducing the thickness of the first conductive adhesive layer and the second conductive adhesive layer, the thickness of the bipolar electrode can be reduced.

[0025] In the above-mentioned bipolar electrode based on the present disclosure, the above-mentioned intermediate conductor may also have a side located on one side of the above-mentioned longitudinal direction when viewed from the above-mentioned stacking direction and constituting a part of the outer edge of the above-mentioned intermediate conductor, and a small wing protruding from the above-mentioned side toward the outside of the above-mentioned longitudinal direction.

[0026] According to the above configuration, when the bipolar electrodes are stacked, the winglets can be used as terminals for potential detection.

[0027] The bipolar battery according to the present disclosure includes: a stacked body formed by stacking a plurality of the bipolar electrodes in the stacking direction; and a sealing body that seals the peripheral edge of the stacked body so as to surround the first active material layer and the second active material layer when viewed from the stacking direction.

[0028] According to the above configuration, by using the above bipolar electrode, it is possible to suppress a decrease in battery performance and conduction failure.

[0029] The manufacturing method of the bipolar electrode based on the present disclosure comprises the steps of stacking the first active material layer, the first current collector, the intermediate conductor, the second current collector and the second active material layer in the stacking direction. The stacking steps include: forming the first active material layer on the first surface of the first current collector having the first surface and the second surface in a front-back relationship; forming the second active material layer on the second main surface of the second current collector having the first main surface and the second main surface in a front-back relationship; bonding the second surface to the surface of the intermediate conductor; and bonding the first main surface to the back of the intermediate conductor. In the step of forming the second active material layer, the second active material layer is formed in such a way that the length of the second active material layer in the longitudinal direction orthogonal to the stacking direction is shorter than that of the first active material layer. In the step of joining the first surface of the second current collector, the second current collector is joined so that the second active material layer is located inside the first active material layer when viewed from the stacking direction. As the intermediate conductor, an intermediate conductor longer than the first current collector and the second current collector is used.

[0030] According to the above structure, the length of the first active material layer is longer than that of the second active material layer, so that when viewed from the stacking direction, a region that does not face the first active material layer can be prevented from being formed in the second active material layer. This can prevent degradation of battery performance.

[0031] Furthermore, the first current collector provided with the first active material layer and the second current collector provided with the second active material layer can be independently bonded to the surface and the back of the intermediate conductor, respectively, so that the bonding state between the second surface of the first current collector and the surface of the intermediate conductor and the bonding state between the first main surface of the second current collector and the back of the intermediate conductor can be stabilized. As a result, poor conduction can be suppressed. Furthermore, the length of the intermediate conductor is longer than the length of the first current collector and the second current collector, so it is possible to suppress the first current collector and the second current collector from protruding from the intermediate conductor when the first current collector and the second current collector are bonded to the intermediate conductor.

[0032] In the above-mentioned method for manufacturing a bipolar electrode based on the present disclosure, the step of forming the above-mentioned first active material layer may also include the step of punching the first active material layer coated on the above-mentioned first surface of the above-mentioned first current collector, and the step of forming the above-mentioned second active material layer may also include the step of punching the second active material layer coated on the above-mentioned first surface of the above-mentioned first current collector. In this case, the pressure for punching the above-mentioned second active material layer is preferably greater than the pressure for punching the above-mentioned first active material layer.

[0033] According to the above structure, the first active material layer and the second active material layer can be provided at a density suitable for battery performance, and desired battery performance can be obtained.

[0034] In the above-mentioned method for manufacturing a bipolar electrode based on the present disclosure, the step of joining the above-mentioned second surface of the above-mentioned first current collector may also include: a step of applying the first conductive adhesive layer to the above-mentioned second surface; and a step of pressing the above-mentioned first current collector toward the above-mentioned intermediate conductor in a state where the applied first conductive adhesive layer is in contact with the above-mentioned surface of the above-mentioned intermediate conductor. In addition, the step of joining the above-mentioned first main surface of the above-mentioned second current collector may also include: a step of applying the second conductive adhesive layer to the above-mentioned second main surface; and a step of pressing the above-mentioned second current collector toward the above-mentioned intermediate conductor in a state where the applied second conductive adhesive layer is in contact with the above-mentioned back surface of the above-mentioned intermediate conductor.

[0035] According to the above configuration, the first current collector and the second current collector can be substantially uniformly joined to the intermediate conductor via the first conductive adhesive layer and the second conductive adhesive layer.

[0036] In the method for producing a bipolar electrode according to the present disclosure, as the first conductive adhesive layer and the second conductive adhesive layer, conductive adhesive layers containing conductive particles obtained by metal-coating resin powder may be used.

[0037] According to the above configuration, since the resin powder is metal-coated, the cost can be reduced compared to the case of using metal particles, and the first current collector and the second current collector can be joined to the intermediate conductor while ensuring a considerable degree of elasticity.

[0038] In the method for manufacturing a bipolar electrode based on the present disclosure, in the step of joining the second surface of the first current collector, the first current collector may be joined to the intermediate conductor in such a manner that the first conductive adhesive layer parallel to the stacking direction is the same as the particle diameter of the conductive particles. In addition, in the step of joining the first surface of the second current collector, the second current collector may be joined to the intermediate conductor in such a manner that the second conductive adhesive layer parallel to the stacking direction is the same as the particle diameter of the conductive particles.

[0039] According to the above configuration, by reducing the thickness of the first conductive adhesive layer and the second conductive adhesive layer, the thickness of the bipolar electrode can be reduced.

[0040] In the above-mentioned method for manufacturing a bipolar electrode based on the present disclosure, the step of forming the above-mentioned first active material layer may also include the step of punching the above-mentioned first active material layer coated on the above-mentioned first surface of the above-mentioned first current collector. The step of forming the above-mentioned second active material layer may also include the step of punching the above-mentioned second active material layer coated on the above-mentioned first surface of the above-mentioned first current collector. In this case, the pressure for punching the above-mentioned first current collector toward the above-mentioned intermediate conductor and the pressure for punching the above-mentioned second current collector toward the above-mentioned intermediate conductor are preferably smaller than the pressure for punching the above-mentioned first active material layer and the pressure for punching the above-mentioned second active material layer, respectively.

[0041] According to the above structure, when the first and second current collectors provided with the first and second active material layers formed at a desired density are independently joined to the intermediate conductor, the influence on the first and second active material layers can be reduced by reducing the pressing pressure.

[0042] In the method for manufacturing a bipolar electrode according to the present disclosure, the length of the first current collector in a longitudinal direction orthogonal to the stacking direction is longer than the length of the second current collector.

[0043] According to the above configuration, by providing the first active material layer on the first current collector which is longer than the second current collector, the first active material layer which is longer than the second active material layer can be reliably formed.

[0044] In the above-mentioned method for manufacturing a bipolar electrode based on the present disclosure, the above-mentioned intermediate conductor may also have a side portion located on one side of the above-mentioned longitudinal direction and constituting a part of the outer edge of the above-mentioned intermediate conductor when viewed from the above-mentioned stacking direction, and a small wing protruding from the above-mentioned side portion toward the outside of the above-mentioned longitudinal direction. In this case, the step of joining the above-mentioned second surface of the above-mentioned first current collector preferably includes the step of positioning the position where the above-mentioned first current collector is joined to the above-mentioned intermediate conductor using the above-mentioned small wing as a mark, and the step of joining the above-mentioned first main surface of the above-mentioned second current collector preferably includes the step of positioning the position where the above-mentioned second current collector is joined to the above-mentioned intermediate conductor using the above-mentioned small wing as a mark.

[0045] According to the above configuration, the accuracy of the joining position can be improved by positioning using the winglet as a mark.

[0046] According to the present disclosure, it is possible to provide a bipolar electrode capable of suppressing a decrease in battery performance and conduction failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic cross-sectional view showing a power storage device according to an embodiment.

[0048] Figure 2 It is a schematic cross-sectional view showing a power storage module according to the embodiment.

[0049] Figure 3 It is a cross-sectional view showing a bipolar electrode according to an embodiment.

[0050] Figure 4 1 is a flowchart showing a process for manufacturing a bipolar electrode according to an embodiment.

[0051] Figure 5 It is shown in Figure 4 FIG. 1 is a diagram showing a step of forming a negative electrode active material layer on a negative electrode collector plate in the process of manufacturing a bipolar electrode.

[0052] Figure 6 It is shown in Figure 4 FIG. 1 is a diagram showing a step of forming a positive electrode active material layer on a positive electrode collector plate in the process of manufacturing a bipolar electrode.

[0053] Figure 7 It is shown in Figure 4 FIG. 1 is a diagram showing a first step of bonding a negative electrode collector plate to a surface of an intermediate conductor in a process of manufacturing a bipolar electrode.

[0054] Figure 8 It is shown in Figure 4 FIG. 1 is a diagram showing a second step of bonding a positive electrode collector plate to the surface of an intermediate conductor in the process of manufacturing a bipolar electrode.

[0055] Fig. 9 It is shown in Figure 4 FIG. 1 is a diagram showing a first step of bonding a positive electrode collector plate to the back surface of an intermediate conductor in the process of manufacturing a bipolar electrode.

[0056] Fig.10 It is shown in Figure 4 FIG. 1 is a diagram showing a second step of the process of bonding a negative electrode collector plate to the back surface of an intermediate conductor in the process of manufacturing a bipolar electrode.

[0057] Fig.11 It is a diagram showing a modified example of the step of forming a negative electrode active material layer on a negative electrode current collector plate.

[0058] Fig.12 It is a diagram showing a first variation of the step of bonding a negative electrode current collector plate to the front surface of an intermediate conductor and the step of bonding a positive electrode current collector plate to the back surface of an intermediate conductor.

[0059] Fig.13 It is a diagram showing a second modification of the step of bonding the negative electrode current collector plate to the surface of the intermediate conductor. DETAILED DESCRIPTION

[0060] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the embodiments described below, the same or common parts are denoted by the same reference numerals in the drawings, and their description will not be repeated.

[0061] Figure 1 2 is a schematic cross-sectional view showing a power storage device according to an embodiment. Figure 1 Next, a power storage device 100 according to an embodiment will be described. The power storage device 100 is used as a storage battery for a vehicle such as a hybrid vehicle or an electric vehicle, for example.

[0062] like Figure 1 As shown, the power storage device 100 includes a module stack 110 and a pair of restraining members 150. The pair of restraining members 150 restrain the module stack 110 from both sides in the stacking direction of the module stack 110. An insulating member is disposed between the pair of restraining members 150 and the module stack 110.

[0063] Module stack 110 includes a plurality of bipolar batteries 1 and a plurality of conductive plates 120 stacked on one another. Bipolar batteries 1 and conductive plates 120 are arranged to be alternately adjacent to one another in the stacking direction of module stack 110 .

[0064] The bipolar battery 1 has a rectangular outer shape when viewed from the stacking direction of the module stack 110. The adjacent bipolar batteries 1 are electrically connected to each other via the conductive plates 120. The positive terminal 130 is connected to the conductive plate 120 located at one of the two ends in the stacking direction of the module stack 110. The negative terminal 140 is connected to the conductive plate 120 located at the other of the two ends in the stacking direction of the module stack 110.

[0065] Bipolar battery 1 is a so-called bipolar battery. More specifically, bipolar battery 1 may be a laminated aqueous battery. Bipolar battery 1 is, for example, a secondary battery such as a nickel-hydrogen secondary battery or a lithium-ion secondary battery, or an electric double-layer capacitor.

[0066] In the bipolar battery 1 , the length in a first direction perpendicular to the stacking direction is about 1300 mm to 1700 mm, and the width in a second direction perpendicular to the stacking direction and the first direction is about 1000 mm to 1400 mm.

[0067] Figure 2 2 is a schematic cross-sectional view showing a power storage module according to an embodiment. Figure 2 , a bipolar battery 1 according to an embodiment will be described.

[0068] like Figure 2 As shown in FIG. 1 , the bipolar battery 1 includes a stack 10 and a sealing portion 20. The stack 10 includes a plurality of bipolar electrodes 11, a plurality of separators 15, terminal electrodes 16 and 17, and an electrolyte. The plurality of bipolar electrodes 11 are arranged along a stacking direction (in the direction of the stacking direction). Figure 2 The bipolar electrodes 11 are stacked in the vertical direction, and a separator 15 is interposed between the bipolar electrodes 11 adjacent to each other.

[0069] The bipolar electrode 11 includes an intermediate conductor 12, a negative electrode portion 13, and a positive electrode portion 14. The negative electrode portion 13, the intermediate conductor 12, and the positive electrode portion 14 are stacked in this order from one side toward the other side in the stacking direction.

[0070] The intermediate conductor 12 is formed of a plate-shaped conductive member. The intermediate conductor 12 may be made of, for example, at least one metal selected from the group consisting of aluminum (Al), stainless steel, nickel (Ni), chromium (Cr), platinum (Pt), niobium (Nb), iron (Fe), titanium (Ti), and zinc (Zn), or may be a conductor obtained by plating the surface of a metal foil. Aluminum is preferably used as the intermediate conductor 12 in order to have strength and be thin.

[0071] The intermediate conductor 12 has a surface 12a located on one side in the stacking direction and a back surface 12b located on the other side in the stacking direction. The negative electrode portion 13 is provided on the surface 12a side of the intermediate conductor 12. The positive electrode portion 14 is provided on the back surface 12b side of the intermediate conductor 12.

[0072] The terminal electrode 16 forms an end of the stacked body 10 on one side in the stacking direction. The terminal electrode 16 includes the intermediate conductor 12 and the positive electrode portion 14. In the terminal electrode 16, the positive electrode portion 14 is provided on the back surface 12b of the intermediate conductor 12, and the negative electrode portion 13 and the positive electrode portion 14 are not provided on the surface 12a.

[0073] The terminal electrode 17 forms an end of the stacked body 10 on the other side in the stacking direction. The terminal electrode 17 includes the intermediate conductor 12 and the negative electrode portion 13. In the terminal electrode 17, the negative electrode portion 13 is provided on the surface 12a of the intermediate conductor 12, and the negative electrode portion 13 and the positive electrode portion 14 are not provided on the back surface 12b.

[0074] The separator 15 is disposed between adjacent bipolar electrodes 11. Specifically, it is disposed between the positive electrode portion 14 of the bipolar electrode 11 located on one side in the stacking direction and the negative electrode portion 13 of the bipolar electrode 11 located on the other side in the stacking direction.

[0075] The separator 15 is formed in a sheet shape, for example. Examples of the separator 15 include porous films made of polyolefin resins such as polyethylene (PE) and polypropylene (PP), woven fabrics or nonwoven fabrics made of polypropylene, polyethylene terephthalate (PET), methylcellulose, etc. The separator 15 may also be reinforced with a vinylidene fluoride resin compound.

[0076] The sealing portion 20 seals the peripheries of the plurality of bipolar electrodes 11 so as to form a space S between the bipolar electrodes 11 adjacent to each other along the stacking direction. The sealing portion 20 seals the space S on the inside.

[0077] The peripheries of the plurality of bipolar electrodes 11 are buried in the sealing portion 20 , whereby the sealing portion 20 holds the plurality of bipolar electrodes 11 .

[0078] The sealing portion 20 is made of, for example, an insulating resin. The sealing portion 20 can be made of, for example, polypropylene (PP), polyphenylene sulfide (PPS), or modified polyphenylene ether (modified PPE).

[0079] An electrolyte is contained in the space S. The electrolyte includes, for example, an alkaline aqueous solution such as an aqueous potassium hydroxide solution. The electrolyte is impregnated in the negative electrode portion 13 , the positive electrode portion 14 , and the separator 15 .

[0080] Figure 32 is a cross-sectional view showing a bipolar electrode according to an embodiment. Figure 3 , a detailed structure of the bipolar electrode 11 according to the embodiment will be described.

[0081] like Figure 3 As shown, in the bipolar electrode 11 , the negative electrode portion 13 includes a negative electrode active material layer 132 as a first active material layer and a negative electrode current collecting plate 131 as a first current collector.

[0082] The negative electrode current collector plate 131 has a first surface 131a located on one side in the stacking direction and a second surface 131b located on the other side in the stacking direction. The negative electrode current collector plate 131 is made of a metal member such as aluminum (Al) foil, for example.

[0083] The negative electrode active material layer 132 is formed by applying the negative electrode active material layer to the first surface 131a and then pressing the negative electrode active material layer 132. The density of the negative electrode active material layer 132 is, for example, 1.4 g / cm 3 To 1.8g / cm 3 degree.

[0084] The density of the negative electrode active material layer 132 is lower than the density of the positive electrode active material layer 142 described later. By setting the densities of the negative electrode active material layer 132 and the positive electrode active material layer 142 to desired values, the battery performance can be improved.

[0085] As the negative electrode active material contained in the negative electrode active material layer, lithium, carbon, a metal compound, an element that can be alloyed with lithium or a compound thereof, etc. can be used.

[0086] The positive electrode portion 14 includes a positive electrode active material layer 142 as a second active material layer and a positive electrode current collecting plate 141 as a second current collector.

[0087] The positive electrode current collector plate 141 has a first main surface 141a located on one side in the stacking direction and a second main surface 141b located on the other side in the stacking direction. The positive electrode current collector plate 141 is made of a metal member such as copper foil, for example.

[0088] The positive electrode active material layer 142 is formed by applying the positive electrode active material layer to the second main surface 141 b and then pressing the positive electrode active material layer 142. The density of the positive electrode active material layer 142 is, for example, 2.2 g / cm 3 To 2.8g / cm 3 degree.

[0089] As the positive electrode active material layer, for example, a layer that can absorb and release charge carriers such as lithium ions can be used. Specifically, as the positive electrode active material, a lithium ion composite metal oxide with a layered rock salt structure, a metal oxide with a spinel structure, a polyanion compound, etc. that can be used as a positive electrode active material for a lithium ion secondary battery can be used. In addition, two or more positive electrode active materials can also be used in combination, for example, the positive electrode active material can also include olivine-type lithium iron phosphate (LiFePO4).

[0090] The second surface 131b of the negative electrode current collector plate 131 located opposite to the first surface 131a provided with the negative electrode active material layer 132 is bonded to the surface 12a of the intermediate conductor 12. Specifically, the second surface 131b is bonded via the first conductive adhesive layer 31 disposed between the second surface 131b and the surface 12a.

[0091] The first main surface 141a of the positive electrode collector plate 141, which is located on the opposite side to the second main surface 141b provided with the positive electrode active material layer 142, is bonded to the back surface 12b of the intermediate conductor 12. Specifically, the first main surface 141a is bonded via the second conductive adhesive layer 32 disposed between the first main surface 141a and the back surface 12b.

[0092] As described above, by using the first conductive adhesive layer 31 and the second conductive adhesive layer 32 , the negative electrode current collector plate 131 and the positive electrode current collector plate 141 can be substantially uniformly joined to the intermediate conductor while suppressing an increase in thickness.

[0093] The first conductive adhesive layer 31 and the second conductive adhesive layer 32 contain a binder resin and a conductive filler. Examples of the binder resin include polyvinyl butyral, cellulose, polyurethane, polyester fiber, epoxy resin, phenolic resin, ester resin, alkyd resin, amide, and imide resin.

[0094] The conductive filler is dispersed in the binder resin at an appropriate density without agglomeration. The conductive filler may include metal particles such as silver, copper, aluminum, nickel, gold, zinc or iron, or conductive particles obtained by coating a resin powder with metal such as silver, copper, aluminum, nickel, gold, zinc or iron.

[0095] When conductive particles obtained by coating resin powder with metal are used, the cost can be reduced compared to the case of using metal particles, and the first and second current collectors can be joined to the intermediate conductor while ensuring a considerable degree of elasticity.

[0096] In addition, the thickness of the first conductive adhesive layer 31 and the second conductive adhesive layer 32 parallel to the stacking direction may be the same as the particle diameter of the conductive particles. Thus, by reducing the thickness of the first conductive adhesive layer 31 and the second conductive adhesive layer 32, the thickness of the bipolar electrode 11 can be reduced.

[0097] In the length direction orthogonal to the stacking direction, the length L4 of the first active material layer is longer than the length L5 of the second active material layer, and when viewed from the stacking direction, the positive electrode active material layer 142 is located inside the negative electrode active material layer 132. Thus, compared with the case where the positive electrode active material layer 142 protrudes from the negative electrode active material layer 132 when viewed from the stacking direction, the formation of dendrites on the positive electrode active material layer 142 side can be suppressed, thereby suppressing the reduction of battery performance.

[0098] In the length direction, the length L1 of the intermediate conductor 12 is longer than the length L2 of the negative collector plate 131 and the length L3 of the positive collector plate 141. Thus, when the negative collector plate 131 and the positive collector plate 141 are joined to the intermediate conductor 12, the negative collector plate 131 and the positive collector plate 141 are prevented from protruding from the intermediate conductor 12.

[0099] As described above, in the bipolar electrode 11 involved in the embodiment, the negative electrode collector plate 131 provided with the negative electrode active material layer 132 and the positive electrode collector plate 141 provided with the positive electrode active material layer 142 can be independently joined to the surface 12a and the back surface 12b of the intermediate conductor 12, respectively, so that the joining state between the second surface 131b of the negative electrode collector plate 131 and the surface 12a of the intermediate conductor 12 and the joining state between the first main surface 141a of the positive electrode collector plate 141 and the back surface 12b of the intermediate conductor 12 can be stabilized.

[0100] As a result, the conductive state between the negative electrode current collecting plate 131 and the intermediate conductor 12 and the conductive state between the positive electrode current collecting plate 141 and the intermediate conductor 12 can be well maintained, and conductive failure can be suppressed.

[0101] In particular, as described above, as the bipolar battery 1, when the length in the first direction perpendicular to the stacking direction is set to about 1300 mm to 1700 mm, the width in the second direction perpendicular to the stacking direction and the first direction is set to about 1000 mm to 1400 mm, and the size of each of the negative electrode collector plate 131 and the positive electrode collector plate 141 is also set to be the same, the above effect can be significantly exerted by maintaining the bonding state well as described above. Furthermore, by using the above-mentioned first conductive adhesive layer 31 and the second conductive adhesive layer 32, a good bonding state can be easily achieved.

[0102] In addition, in the stacking direction, the thickness of the intermediate conductor 12 is thicker than the thickness of the negative electrode collector plate 131. The thickness of the negative electrode collector plate 131 may also be thinner than the thickness of the positive electrode collector plate 141. By thinning the negative electrode collector plate 131, the manufacturing cost can be reduced. By thickening the intermediate conductor 12, the negative electrode collector plate 131 can be thinned. By setting the thickness relationship as described above, the negative electrode collector plate 131 and the positive electrode collector plate 141 can be reliably joined to the intermediate conductor 12 while ensuring strength. In addition, the thickness of the bipolar battery 1 in which the bipolar electrodes 11 are stacked can be suppressed, and the mounting efficiency can be improved.

[0103] (Manufacturing method)

[0104] Figure 4 1 is a flowchart showing a process for manufacturing a bipolar electrode according to an embodiment. Figures 5 to 10 It is shown Figure 4 FIG. 1 is a diagram showing a predetermined process of manufacturing a bipolar electrode. Figures 4 to 10 , describing the manufacturing process of the bipolar electrode involved in the embodiment.

[0105] like Figure 4 As shown, the manufacturing process of the bipolar electrode includes a step (S10) of stacking the negative electrode active material layer 132, the negative electrode collector plate 131, the intermediate conductor 12, the positive electrode collector plate 141, and the positive electrode active material layer 142 having a polarity different from that of the negative electrode active material layer 132 in the stacking direction. Step (S10) includes steps (S11) to (S14) described later.

[0106] Figure 5 It is shown in Figure 4 FIG. 1 is a diagram showing a step of forming a negative electrode active material layer on a negative electrode collector plate in the process of manufacturing a bipolar electrode.

[0107] like Figure 4 as well as Figure 5 As shown, when manufacturing the bipolar electrode 11, in step (S11), the negative electrode active material layer 132 is formed on the first surface 131a of the strip-shaped current collector 131A serving as the negative electrode current collector plate 131. Specifically, the negative electrode active material layer 132 applied on the first surface 131a is sandwiched and pressed by a pair of pressure rollers 41 and 42.

[0108] The pressure with which the negative electrode active material layer 132 is pressed by the pair of press rolls 41 and 42 is, for example, approximately 500 MPa to 1500 MPa.

[0109] The negative electrode active material layer 132 may be applied to the first surface 131 a at a predetermined pitch with a certain interval. In this case, after the negative electrode active material layer 132 is pressed by a pair of press rolls 41 and 42 , the strip-shaped current collector 131A is cut along the cutting line CL1 .

[0110] Figure 6 It is shown in Figure 4 FIG. 1 is a diagram showing a step of forming a positive electrode active material layer on a positive electrode collector plate in the process of manufacturing a bipolar electrode.

[0111] like Figure 4 as well as Figure 6 As shown, in step (S12), the positive electrode active material layer 142 is formed on the second main surface 141b of the strip-shaped current collector 141A serving as the positive electrode current collector plate 141. Specifically, the positive electrode active material layer 142 applied on the second main surface 141b is sandwiched and pressed by a pair of press rolls 43 and 44.

[0112] The pressure with which the positive electrode active material layer 142 is pressed by the pair of press rolls 43 and 44 is, for example, approximately 2000 MPa to 3000 MPa.

[0113] Thus, the pressure for pressing the positive electrode active material layer 142 is greater than the pressure for pressing the negative electrode active material layer 132. Thus, the negative electrode active material layer 132 and the positive electrode active material layer 142 can be arranged at a density suitable for battery performance, and desired battery performance can be obtained.

[0114] The positive electrode active material layer 142 may be applied to the second main surface 141 b at a predetermined pitch at intervals. In this case, after the positive electrode active material layer 142 is pressed by a pair of press rolls 43 and 44 , the strip-shaped current collector 141A is cut along the cutting line CL2 .

[0115] The positive electrode active material layer 142 is formed so that the length in the longitudinal direction perpendicular to the stacking direction is shorter than that of the negative electrode active material layer 132 .

[0116] In addition, the above-mentioned step (S12) may be performed in parallel with the step (S11), after the step (S11), or before the step (S11).

[0117] Again Figure 4 As shown, in step (S13), the second surface 131b of the negative electrode collector plate 131 is bonded to the surface 12a of the intermediate conductor 12. That is, the second surface 131b located on the opposite side to the first surface 131a provided with the negative electrode active material layer 132 is bonded to the surface 12a.

[0118] Figure 7It is shown in Figure 4 FIG. 1 is a diagram showing a first step of bonding a negative electrode collector plate to a surface of an intermediate conductor in a process of manufacturing a bipolar electrode.

[0119] like Figure 7 As shown, in the first step of the step (S13), the first conductive adhesive layer 31 is applied to the second surface 131b. The first conductive adhesive layer 31 is applied by a suitable coating device such as a transfer device. The thickness of the applied first conductive adhesive layer 31 can also be adjusted by a scraper or the like in a manner to achieve a predetermined thickness. As the first conductive adhesive layer 31, the example described above is used.

[0120] Figure 8 It is shown in Figure 4 FIG. 1 is a diagram showing a second step of bonding a negative electrode collector plate to the surface of an intermediate conductor in the process of manufacturing a bipolar electrode.

[0121] like Figure 8 As shown, in the second step of the step ( S13 ), the negative electrode current collector plate 131 is pressed toward the intermediate conductor 12 in a state where the applied first conductive adhesive layer 31 is in contact with the surface 12 a of the intermediate conductor 12 .

[0122] Specifically, the negative electrode collector plate 131 provided with the negative electrode active material layer 132 is placed on the surface 12a so that the first conductive adhesive layer 31 is interposed between the surface 12a and the second surface 131b of the intermediate conductor 12. The negative electrode collector plate 131 provided with the negative electrode active material layer 132 and the intermediate conductor 12 are sandwiched and pressed by a pair of press rolls 51 and 52.

[0123] The pressure for pressing the negative electrode current collector plate 131 toward the intermediate conductor 12 is, for example, approximately 0.5 MPa to 1.5 MPa.

[0124] When an adhesive containing conductive particles is used as the first conductive adhesive layer 31, the thickness of the first conductive adhesive layer 31 is preferably the same as that of the conductive particles when the negative electrode collector plate 131 is bonded to the intermediate conductor 12. Thus, the thickness of the first conductive adhesive layer 31 can be reduced, and the thickness of the manufactured bipolar electrode 11 can be reduced.

[0125] Again Figure 4 As shown, in step (S14), the first main surface 141a of the positive electrode collector plate 141 is bonded to the back surface 12b of the intermediate conductor 12. That is, the first main surface 141a located opposite to the second main surface 141b provided with the positive electrode active material layer 142 is bonded to the back surface 12b.

[0126] Fig. 9It is shown in Figure 4 FIG. 1 is a diagram showing a first step of bonding a positive electrode collector plate to the back surface of an intermediate conductor in the process of manufacturing a bipolar electrode.

[0127] like Fig. 9 As shown, in the first step of the step (S14), the second conductive adhesive layer 32 is applied to the first main surface 141a. The second conductive adhesive layer 32 is applied in substantially the same manner as the first conductive adhesive layer 31. As the second conductive adhesive layer 32, the above-described example is used.

[0128] Fig.10 It is shown in Figure 4 FIG. 1 is a diagram showing a second step of the process of bonding a positive electrode collector plate to the back surface of an intermediate conductor in the process of manufacturing a bipolar electrode.

[0129] like Fig.10 As shown, in the second step of the step ( S14 ), the positive electrode collector plate 141 is pressed toward the intermediate conductor 12 in a state where the applied second conductive adhesive layer 32 is in contact with the back surface 12 b of the intermediate conductor 12 .

[0130] When the positive electrode collector plate 141 is pressed, as described above, the negative electrode collector plate 131 provided with the negative electrode active material layer 132 is in a state of being bonded to the surface 12a of the intermediate conductor 12. In this state, the positive electrode collector plate 141 provided with the positive electrode active material layer 142 is placed on the surface 12a in a manner that the second conductive adhesive layer 32 is interposed between the back surface 12b of the intermediate conductor 12 and the first main surface 141a. At this time, the positive electrode collector plate 141 is placed in a manner that the positive electrode active material layer 142 is located inside the negative electrode active material layer 132 when viewed from the stacking direction (the normal direction of the surface 12a).

[0131] Next, the negative electrode collector plate 131 provided with the negative electrode active material layer 132 is bonded to the front surface 13 a and the positive electrode collector plate 141 provided with the positive electrode active material layer 142 is placed on the back surface 12 b , and they are sandwiched and pressed between a pair of press rolls 53 and 54 .

[0132] When the positive current collector plate 141 is joined to the intermediate conductor 12 in this manner, the pressure at which the positive current collector plate 141 is pressed toward the intermediate conductor 12 is about the same as the pressure at which the negative current collector plate 131 is pressed toward the intermediate conductor 12 , for example, about 0.5 MPa to 1.5 MPa.

[0133] The pressure with which the negative electrode collector plate 131 is pressed toward the intermediate conductor 12 in step (S13) and the pressure with which the positive electrode collector plate 141 is pressed toward the intermediate conductor 12 in step (S14) are respectively smaller than the pressure with which the negative electrode active material layer 132 is pressed in step (S11) and the pressure with which the positive electrode active material layer 142 is pressed in step (S12).

[0134] When a negative electrode collector plate 131 having a negative electrode active material layer 132 formed at a desired density and a positive electrode collector plate 141 having a positive electrode active material layer 142 formed at a desired density are independently joined to an intermediate conductor 12, the influence on the negative electrode active material layer 132 and the positive electrode active material layer 142 can be suppressed by reducing the stamping pressure in steps (S13) and (S14).

[0135] When an adhesive containing conductive particles is used as the second conductive adhesive layer 32, the thickness of the second conductive adhesive layer 32 is preferably the same as that of the conductive particles when the positive electrode collector plate 141 is bonded to the intermediate conductor 12. Thus, the thickness of the second conductive adhesive layer 32 can be reduced, and the thickness of the manufactured bipolar electrode 11 can be reduced.

[0136] Furthermore, when a material obtained by metal-coating a resin powder is used as the conductive particles included in the first conductive adhesive layer 31 and the second conductive adhesive layer 32, the negative electrode collector plate 131 and the positive electrode collector plate 141 can be joined to the intermediate conductor 12 while ensuring a considerable degree of elasticity while reducing costs compared to conductive particles.

[0137] (Variation Example)

[0138] Furthermore, in the method for manufacturing a bipolar electrode according to the embodiment, a part of the manufacturing process may be changed as described below.

[0139] Fig.11 FIG. 2 is a diagram showing a modified example of the step of forming the first active material layer on the first current collector. Fig.11 As shown, the negative electrode active material layer 132 may be applied to the first surface 131a in a continuous manner in the extending direction of the strip-shaped current collector 131A, and then pressed by a pair of pressure rollers 41, 42. In this case, the positive electrode portion 14 may be punched out from the strip-shaped current collector 131A in a manner of a predetermined size after the pressing. In addition, this process may also be applied to the process of forming the positive electrode active material layer 142 on the positive electrode collector plate 141.

[0140] Fig.12It is a diagram showing a first modification of the step of bonding the first current collector to the front surface of the intermediate conductor and the step of bonding the second current collector to the back surface of the intermediate conductor.

[0141] like Fig.12 As shown, the step of bonding the negative electrode current collecting plate 131 to the front surface 12 a of the intermediate conductor 12 and the step of bonding the positive electrode current collecting plate 141 to the back surface 12 b of the intermediate conductor 12 may be performed continuously.

[0142] Specifically, in the step of joining the negative electrode collector plate 131 to the surface 12a of the intermediate conductor 12, the negative electrode collector plate 131 is joined to the surface 12a of the strip-shaped intermediate conductor 12A conveyed by the conveying rollers 70. The joining method is substantially the same as that of the above embodiment.

[0143] The intermediate conductor 12A is conveyed, for example, from a state where the surface 12a is located on the upper side to a state where the back surface 12b is located on the upper side when passing through the conveying rollers 70. Next, the positive electrode collector plate 141 is joined to the back surface 12b located on the upper side. The joining method is substantially the same as in the above embodiment.

[0144] Thus, in the above-mentioned first variant, after the negative electrode collector plate 131 is joined to the surface 12a of the continuously transported intermediate conductor 12A, the positive electrode collector plate 141 is joined to the back side 12b of the intermediate conductor 12A at a position corresponding to the joined negative electrode collector plate 131 on the downstream side of the transport direction of the intermediate conductor 12A.

[0145] The bipolar electrode 11 is manufactured by cutting the intermediate conductor 12A to which the negative electrode current collecting plate 131 and the positive electrode current collecting plate 141 are joined.

[0146] Fig.13 1 is a diagram showing a second variation of the process of bonding the first current collector to the surface of the intermediate conductor. The strip-shaped intermediate conductor 12A may also have a side portion 121 located on one side of the longitudinal direction orthogonal to the stacking direction and constituting a part of the outer edge of the intermediate conductor 12, and a small wing 12c protruding from the side portion 121 toward the outside in the longitudinal direction (one side in the longitudinal direction).

[0147] In this case, if Fig.13 As shown, in the process of joining the second surface of the negative electrode collector plate 131, the winglet 12c is used as a mark to locate the position where the negative electrode collector plate 131 is joined to the intermediate conductor 12A. Specifically, a position detection device such as an image reader is used to detect the position of the winglet 12c, and the position where the negative electrode collector plate 131 is joined is determined based on the detected position information.

[0148] The length of the intermediate conductor 12A in the longitudinal direction is longer than the length of the negative electrode collector plate 131. When the negative electrode collector plate 131 is joined to the intermediate conductor 12A, both ends of the intermediate conductor 12A in the longitudinal direction are located outside the negative electrode collector plate 131 in the longitudinal direction.

[0149] Similarly, in the process of joining the first main surface 141a of the positive electrode collector plate 141, the winglet 12c is used as a mark to locate the position where the positive electrode collector plate 141 is joined to the intermediate conductor 12A. Specifically, a position detection device such as an image reader is used to detect the position of the winglet 12c, and the position where the positive electrode collector plate 141 is joined is determined based on the detected position information.

[0150] The length of the intermediate conductor 12A in the longitudinal direction is longer than that of the positive current collector plate 141. When the positive current collector plate 141 is joined to the intermediate conductor 12A, both ends of the intermediate conductor 12A in the longitudinal direction are located outside the positive current collector plate 141 in the longitudinal direction.

[0151] In addition, in the first and second modified examples, the following cases are illustrated and described, that is, the intermediate conductor 12A is conveyed in a continuous strip shape, and the negative electrode collector plate 131 and the positive electrode collector plate 141 are sequentially joined to the conveyed intermediate conductor 12A in a strip shape, but the present invention is not limited to this. The intermediate conductor 12 that has been cut in advance into the size of the bipolar electrode 11 may be conveyed independently, and the negative electrode collector plate 131 and the positive electrode collector plate 141 may be sequentially joined to the intermediate conductor 12. The pre-cut intermediate conductor 12 itself may also be provided with a small wing 12c. The small wing 12c can be used as a voltage detection terminal for detecting the voltage between the mutually adjacent bipolar electrodes.

[0152] The embodiments disclosed herein are intended to be illustrative in all respects and are not restrictive. The scope of the present invention is indicated by the claims, and all modifications within the meaning and scope equivalent to the claims are included.

[0153] Explanation of symbols

[0154] 1 bipolar battery; 10 stack; 11 bipolar electrode; 12, 12A intermediate conductor; 12a, 13a surface; 12b back surface; 12c tab; 13 negative electrode; 14 positive electrode; 15 separator; 16, 17 terminal electrode; 20 sealing portion; 31 first conductive adhesive layer; 32 second conductive adhesive layer; 41, 42, 43, 44, 51, 52, 53, 54, 55, 56 pressure roller; 70 conveying roller; 100 power storage device; 1 10 module stack; 120 conductive plate; 121 edge; 130 positive terminal; 131 negative collector plate; 131A collector; 131a first surface; 131b second surface; 132 negative active material layer; 140 negative terminal; 141 positive collector plate; 141A collector; 141a first main surface; 141b second main surface; 142 positive active material layer; 150 restraining component; CL1, CL2 cutting lines; L1, L2, L3, L4, L5 lengths.

Claims

1. A bipolar electrode, The invention comprises a first active material layer, a first current collector, an intermediate conductor, a second current collector, and a second active material layer which are sequentially stacked in a stacking direction. The intermediate conductor has a surface located on one side in the stacking direction and a back surface located on the other side in the stacking direction. The first current collector has a first surface located on the one side in the stacking direction and a second surface located on the other side in the stacking direction. The second current collector has a first main surface located on the one side in the stacking direction and a second main surface located on the other side in the stacking direction. The first active material layer is provided on the first surface of the first current collector. The second active material layer is provided on the second main surface of the second current collector. The second surface of the first current collector is bonded to the surface of the intermediate conductor, The first main surface of the second current collector is bonded to the back surface of the intermediate conductor. In a longitudinal direction perpendicular to the stacking direction, the length of the first active material layer is longer than the length of the second active material layer. The second active material layer is located inside the first active material layer when viewed in the stacking direction. In the longitudinal direction, the length of the intermediate conductor is longer than the lengths of the first current collector and the second current collector.

2. The bipolar electrode according to claim 1, wherein: The density of the first active material layer is lower than the density of the second active material layer.

3. The bipolar electrode according to claim 1 or 2, wherein: In the longitudinal direction, the length of the first current collector is longer than the length of the second current collector.

4. The bipolar electrode according to claim 1 or 2, wherein: have: a first conductive adhesive layer bonding the second surface of the first current collector and the surface of the intermediate conductor; as well as The second conductive adhesive layer bonds the first main surface of the second current collector and the back surface of the intermediate conductor.

5. The bipolar electrode according to claim 4, wherein: The first conductive adhesive layer and the second conductive adhesive layer include conductive particles obtained by metal-coating resin powder.

6. The bipolar electrode according to claim 5, wherein: The thickness of the first conductive adhesive layer and the second conductive adhesive layer parallel to the stacking direction is approximately the same as the particle diameter of the conductive particles.

7. The bipolar electrode according to claim 1 or 2, wherein: The intermediate conductor has a side portion located on one side in the longitudinal direction when viewed from the stacking direction and constituting a part of an outer edge of the intermediate conductor, and a winglet protruding from the side portion toward an outer side in the longitudinal direction.

8. A bipolar battery comprising: A stacked body, formed by stacking a plurality of bipolar electrodes according to claim 1 or 2 along the stacking direction; and The sealing body seals the peripheral portion of the stacked body so as to surround the first active material layer and the second active material layer when viewed in the stacking direction.

9. A method for manufacturing a bipolar electrode, comprising the step of stacking a first active material layer, a first current collector, an intermediate conductor, a second current collector, and a second active material layer in a stacking direction, The stacking process includes: forming the first active material layer on the first surface of the first current collector having a first surface and a second surface in a front-back relationship with each other; forming the second active material layer on the second main surface of the second current collector having a first main surface and a second main surface in a front-back relationship with each other; a step of bonding the second surface to the surface of the intermediate conductor; and a step of bonding the first main surface to the back surface of the intermediate conductor, In the step of forming the second active material layer, the second active material layer is formed so that the length of the second active material layer in a longitudinal direction orthogonal to the stacking direction is shorter than that of the first active material layer. In the step of bonding the first surface of the second current collector, the second current collector is bonded so that the second active material layer is located inside the first active material layer when viewed from the stacking direction. As the intermediate conductor, an intermediate conductor having a length longer than that of the first current collector and the second current collector is used.

10. The method for manufacturing a bipolar electrode according to claim 9, wherein: The step of forming the first active material layer includes a step of pressing the first active material layer coated on the first surface of the first current collector. The step of forming the second active material layer includes the step of pressing the second active material layer coated on the second main surface of the second current collector. The pressure with which the second active material layer is pressed is greater than the pressure with which the first active material layer is pressed.

11. The method for manufacturing a bipolar electrode according to claim 9, wherein: The step of joining the second surface of the first current collector includes: applying a first conductive adhesive layer to the second surface; and pressing the first current collector toward the intermediate conductor in a state where the applied first conductive adhesive layer contacts the surface of the intermediate conductor. The process of joining the first main surface of the second current collector includes: applying a second conductive adhesive layer to the second main surface; and pressing the second current collector toward the intermediate conductor in a state where the applied second conductive adhesive layer contacts the back surface of the intermediate conductor.

12. The method for manufacturing a bipolar electrode according to claim 11, wherein: As the first conductive adhesive layer and the second conductive adhesive layer, conductive adhesive layers containing conductive particles obtained by metal-coating resin powder are used.

13. The method for manufacturing a bipolar electrode according to claim 12, wherein: In the step of joining the second surface of the first current collector, the first current collector is joined to the intermediate conductor in such a manner that the first conductive adhesive layer parallel to the stacking direction has the same particle diameter as the conductive particles. In the step of bonding the first surface of the second current collector, the second current collector is bonded to the intermediate conductor such that the second conductive adhesive layer parallel to the stacking direction has the same particle diameter as the conductive particles.

14. The method for manufacturing a bipolar electrode according to any one of claims 11 to 13, wherein: The step of forming the first active material layer includes a step of pressing the first active material layer coated on the first surface of the first current collector. The step of forming the second active material layer includes the step of pressing the second active material layer coated on the second main surface of the second current collector. The pressure for pressing the first current collector toward the intermediate conductor and the pressure for pressing the second current collector toward the intermediate conductor are respectively smaller than the pressure for pressing the first active material layer and the pressure for pressing the second active material layer.

15. The method for manufacturing a bipolar electrode according to any one of claims 9 to 13, wherein: The intermediate conductor has a side portion located on one side in the longitudinal direction when viewed from the stacking direction and constituting a part of the outer edge of the intermediate conductor, and a winglet protruding from the side portion toward the outside in the longitudinal direction. The step of joining the second surface of the first current collector includes the step of positioning a position where the first current collector is joined to the intermediate conductor using the winglet as a mark, The step of bonding the first main surface of the second current collector includes the step of positioning a position where the second current collector is bonded to the intermediate conductor using the small wing as a mark.

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