Power storage device, method for manufacturing power storage device, and electrolytic plating method

Abstract

The power storage device (1, 1A, 1B, 1C) comprises a stack (2) of bipolar electrodes (3), wherein the bipolar electrodes (3) comprise a steel plate (S) and a plating layer (30) provided on the surface of the steel plate (S). The plating layer (30) comprises: a base nickel plating layer (31) provided on the surface of the steel plate (S); and a main nickel plating layer (32) provided on the base nickel plating layer (31) and having a larger surface roughness than the base nickel plating layer (31).

Description

Technical Field

[0001] One aspect of the present invention relates to a power storage device, a method for manufacturing a power storage device, and an electrolytic plating method. Background Art

[0002] Patent document 1 describes a bipolar secondary battery. The bipolar secondary battery includes: a bipolar electrode having a positive electrode on one side of a metal current collector and a negative electrode on the other side of the current collector; a separator sandwiched between the positive electrode and the negative electrode; and a sealing material in a frame shape surrounding a single cell composed of a positive electrode, a negative electrode and a separator, and crimped between the current collectors. In the bipolar secondary battery, the sealing material is made of resin, and has a high-voltage connection portion surrounding the single cell.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2014-56799 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] However, in order to reduce costs in the manufacture of power storage devices, research has been conducted on using nickel-plated steel plates as current collectors. Generally, the surface shape of the plating layer formed on the surface of the steel plate by nickel plating is a shape that follows the surface shape of the steel plate. In this case, depending on the surface shape of the steel plate, defects such as pinholes may occur in the plating layer on the surface of the current collector. In order to suppress the occurrence of such defects, it is desirable to reduce the influence of the surface shape of the steel plate on the electrode performance.

[0008] One aspect of the present invention aims to provide an electricity storage device, a method for manufacturing an electricity storage device, and an electrolytic plating method, which are capable of suppressing the influence of the surface shape of a steel sheet on electrode performance.

[0009] Solutions for solving problems

[0010] A storage device according to one aspect of the present invention comprises a stack of electrodes, the electrodes comprising a steel plate and a plating layer arranged on the surface of the steel plate, the plating layer comprising: a base nickel plating layer, which is arranged on the surface of the steel plate; and a main nickel plating layer, which is arranged on the base nickel plating layer and has a surface roughness greater than that of the base nickel plating layer.

[0011] In the power storage device, a base nickel plating layer is provided on the surface of the steel plate, and a main nickel plating layer is provided on the base nickel plating layer. Therefore, the shape of the main nickel plating layer located on the surface side of the plating layer is not easily affected by the surface shape of the steel plate. Therefore, according to the above power storage device, the influence of the surface shape of the steel plate on the electrode performance can be suppressed. Moreover, the surface roughness of the main nickel plating layer is greater than the surface roughness of the base nickel plating layer. As a result, the surface area of ​​the plating layer becomes larger, which can improve the heat dissipation of the electrode, etc.

[0012] The power storage device according to one aspect of the present invention may also be provided with a resin spacer arranged along the peripheral portion of the electrode and in contact with the plating layer, the plating layer having a plurality of protrusions protruding in a direction intersecting with the extension direction of the surface of the steel plate, at least a portion of the plurality of protrusions having a rough head shape with the tip becoming thicker as it goes from the base end side to the top end side, and a portion of the resin spacer is between two adjacent protrusions among the plurality of protrusions and at least one of the protrusions having a rough head shape from the top end side to the base end side. In this case, it is possible to restrict the movement of a portion of the resin spacer between the two adjacent protrusions in a direction away from the base end of the protrusion. Thus, it is possible to suppress the resin spacer from peeling off from the plating layer.

[0013] In one aspect of the present invention, the storage device may include a main nickel plating layer that includes a plurality of protrusions protruding in a direction intersecting with the extension direction of the surface of the steel plate, and at least a portion of the plurality of protrusions has a rough head shape whose tip becomes thicker as it goes from the base end side to the tip side.

[0014] A storage device according to one aspect of the present invention comprises a stack of electrodes, the electrodes comprising a steel plate and a plating layer arranged on the surface of the steel plate, the plating layer comprising: a base nickel plating layer, which is arranged on the surface of the steel plate; and a main nickel plating layer, which is arranged on the base nickel plating layer and includes a plurality of protrusions protruding in a direction intersecting with an extension direction of the surface of the steel plate, at least a portion of the plurality of protrusions being in a rough head shape with the tip becoming thicker as it goes from the base end side to the tip side.

[0015] However, in order to achieve cost reduction in the manufacture of power storage devices, research has been conducted on using a steel plate that has been subjected to a nickel plating treatment as a current collector. Generally, the surface shape of the plating layer formed on the surface of the steel plate by the nickel plating treatment is a shape that follows the surface shape of the steel plate. In this case, from the perspective of heat dissipation of the electrode, the surface area of ​​the plating layer may be insufficient. Therefore, an object of one aspect of the present invention is to provide a power storage device having an electrode including a steel plate and having a sufficient surface area, and a method for manufacturing the same.

[0016] In the power storage device, the plating layer includes a main nickel plating layer, and the main nickel plating layer includes a plurality of protrusions protruding in a direction intersecting with the extension direction of the surface of the steel plate. Therefore, the surface area of ​​the main nickel plating layer provided on the surface side is larger than the surface area of ​​the plating layer only along the surface shape of the steel plate. Moreover, at least a part of the plurality of protrusions is in a rough head shape whose top becomes thicker as it goes from the base end side to the top end side. The area of ​​the top of the protrusion in the rough head shape is larger than the area of ​​the top of the protrusion in the thin head shape which is usually provided. Therefore, the above-mentioned power storage device can include an electrode including a steel plate and having a sufficient surface area.

[0017] The power storage device according to one aspect of the present invention may also include a resin spacer arranged along the peripheral portion of the electrode and in contact with the plating layer, wherein a portion of the resin spacer is located from the top end side to the base end side between two adjacent protrusions among a plurality of protrusions and at least one of which has a rough head shape.

[0018] In the power storage device according to one aspect of the present invention, the average height of the plurality of protrusions may be 15 μm to 30 μm. In this case, not only breakage of the protrusions can be suppressed, but also separation of the resin spacer from the plating layer can be satisfactorily suppressed.

[0019] In the power storage device of one aspect of the present invention, at least a portion of the plurality of protrusions may overlap a plurality of deposited metals. In this case, a surface of the protrusion overlapped with the plurality of deposited metals is formed with concavities and convexities. Therefore, a portion of the resin spacer engages with the concavities and convexities on the surface of the protrusion, thereby effectively preventing the resin spacer from peeling off from the plating layer.

[0020] In the power storage device according to the aspect of the present invention, the deposited metal may be spherical.

[0021] The power storage device according to one aspect of the present invention may be a nickel-hydrogen secondary battery, the steel plate may be formed of nickel, and the deposited metal may be nickel.

[0022] In the power storage device of one aspect of the present invention, at least a portion of the plurality of protrusions may have a plurality of nickel crystals overlapping. In this case, a surface of the protrusion having the plurality of nickel crystals overlapping is formed with concavities and convexities. Therefore, a portion of the resin spacer engages with the concavities and convexities on the surface of the protrusion, thereby being able to effectively suppress the resin spacer from peeling off from the plating layer.

[0023] In the power storage device according to one aspect of the present invention, the number of protrusions per unit area of ​​the main nickel plating layer may be 2,500 to 7,000 in a plan view. In this case, it is possible to suppress contact between adjacent protrusions and to ensure a sufficient surface area of ​​the plating layer.

[0024] A method for manufacturing a power storage device according to one aspect of the present invention comprises the steps of: preparing a steel sheet; forming a base nickel plating layer on a surface of the steel sheet; and forming a main nickel plating layer having a larger surface roughness than the base nickel plating layer on the base nickel plating layer.

[0025] In the manufacturing method of the power storage device, a base nickel plating layer is provided on the surface of the steel plate, and a main nickel plating layer is provided on the base nickel plating layer. Therefore, the shape of the main nickel plating layer is not easily affected by the surface shape of the steel plate. Therefore, according to the above power storage device, the influence of the surface shape of the steel plate on the electrode performance can be suppressed. Moreover, the surface roughness of the main nickel plating layer is greater than the surface roughness of the base nickel plating layer. As a result, the surface area of ​​the plating layer becomes larger, which can improve the heat dissipation of the electrode, etc.

[0026] In the method for manufacturing an electric storage device according to one aspect of the present invention, the step of: 2 Above 5.0A / dm 2 Under the following conditions, the steel plate is immersed in a nickel bath in which the nickel concentration is set to be 0.5 mol / L or more and 2.0 mol / L or less, thereby forming a base nickel plating layer having a plurality of protrusions on the surface of the steel plate. In this case, the average height and shape of the plurality of protrusions provided on the base nickel plating layer can be well controlled. Therefore, nickel is easy to grow from the protrusions, and the shape of the main nickel plating layer is further less susceptible to the surface shape of the steel plate.

[0027] In the method for manufacturing a power storage device according to one aspect of the present invention, the steel sheet may be immersed in the nickel bath for a period of 150 to 2,400 seconds under the condition that the temperature of the nickel bath is set to 40 to 65° C. In this case, the average height and shape of the plurality of projections can be more well controlled.

[0028] In a method for manufacturing a storage battery device according to one aspect of the present invention, the main nickel plating layer may include a plurality of protrusions protruding in a direction intersecting with an extension direction of a surface of a steel plate, and in a process of forming the main nickel plating layer, at least a portion of the plurality of protrusions may be configured to have a rough head shape whose tip becomes thicker as it goes from the base end side to the tip side.

[0029] A method for manufacturing a storage battery device according to one aspect of the present invention comprises the following steps: preparing a steel plate; forming a base nickel plating layer on the surface of the steel plate; and forming a main nickel plating layer on the base nickel plating layer, the main nickel plating layer having a plurality of protrusions protruding in a direction intersecting with an extension direction of the surface of the steel plate, wherein in the step of forming the main nickel plating layer, at least a portion of the plurality of protrusions are configured to have a rough head shape whose tip becomes thicker as it goes from the base end side to the tip side.

[0030] In the manufacturing method of these power storage devices, a main nickel-plated layer having a plurality of protrusions is formed on the base nickel-plated layer. Therefore, the surface area of ​​the main nickel-plated layer provided on the surface side is larger than the surface area of ​​the plating layer which only follows the surface shape of the steel plate. Moreover, at least a part of the plurality of protrusions is formed into a rough head shape whose top becomes thicker as it goes from the base end side to the top end side. The area of ​​the top of the protrusion having the rough head shape is larger than the area of ​​the top of the protrusion having the thin head shape which is usually provided. Therefore, according to the above-mentioned manufacturing method, a power storage device having an electrode including a steel plate and having a sufficient surface area can be manufactured.

[0031] The method for manufacturing an electric storage device according to one aspect of the present invention may include: 2 Above 50A / dm 2 Under the following conditions, the steel sheet provided with the base nickel plating layer is immersed in a Watt bath in which the nickel concentration is set to be greater than 0.15 mol / L and less than 0.30 mol / L, thereby forming the main nickel plating layer on the base nickel plating layer. In this case, it is easy to form a protrusion in the shape of a rough head, so that the surface area of ​​the main nickel plating layer can be further increased.

[0032] A method for manufacturing a power storage device according to one aspect of the present invention may also be to immerse a steel plate provided with a base nickel plating layer in a Watts bath set at a temperature of 30° C. to 60° C. for a period of 30 seconds to 60 seconds, thereby forming a main nickel plating layer on the base nickel plating layer. In this case, it is easier to form a protrusion in the shape of a rough head, so that the surface area of ​​the main nickel plating layer can be further increased.

[0033] In one aspect of the present invention, the method for manufacturing a power storage device may be such that, in the step of forming the main nickel plating layer, the relative speed between the base nickel plating layer and the Watt bath is 1.0 m / s or less. In this case, the number of protrusions per unit area on the surface of the main nickel plating layer can be well controlled.

[0034] In one aspect of the present invention, a method for manufacturing a power storage device may include overlapping a plurality of nickel crystals on at least a portion of a plurality of protrusions in the step of forming a main nickel plating layer. In this case, a surface of the protrusion on which the plurality of nickel crystals overlap is formed with irregularities, and the surface area of ​​the protrusion becomes larger.

[0035] A method for manufacturing a storage battery device according to one aspect of the present invention may be that at least one of the steps of forming a base nickel plating layer and forming a main nickel plating layer includes: a first preparation step of preparing: a first clamping member, the entire surface of whose conductive member is insulated and provided with an opening; and a second clamping member, the entire surface of whose conductive member is insulated; a second preparation step of stripping off the insulating coating from a portion of one of the first clamping member and the second clamping member to form an exposed portion that exposes the conductive member of the one clamping member; and a plating treatment step of clamping the substrate by the first clamping member and the second clamping member and immersing the substrate as a cathode in a plating solution in such a manner that the opening is arranged at an area of ​​the substrate where plating treatment is desired and the exposed portion is arranged at a portion of the substrate where current is desired to be supplied, thereby supplying current to the conductive member of one of the first clamping member and the second clamping member having the exposed portion.

[0036] In the manufacturing method of the power storage device, before the substrate is clamped by the first clamping member and the second clamping member, a power supply portion for supplying power to the substrate can be formed by a simple operation of peeling off a portion of the insulating coating from only one of the first clamping member and the second clamping member. The substrate in contact with the exposed portion can be energized by the clamping member formed with the exposed portion. Therefore, if the clamping members are arranged in a manner such that the exposed portion is arranged at a portion of the substrate to which current is desired to be supplied when the substrate is clamped by the first clamping member and the second clamping member, the substrate can receive current supply from the exposed portion. As described above, in order to form the power supply portion, only a portion of the insulating film of the clamping member is peeled off, so the power supply portion can be arbitrarily changed. As a result, the current supply portion can be easily changed for the substrate that becomes the cathode during electrolytic plating.

[0037] In the method for manufacturing a power storage device according to one aspect of the present invention, in the second preparation step, an exposed portion is formed on the first clamping member, and in the plating step, current is supplied to the first clamping member having the exposed portion formed thereon. Thus, current can be supplied from around the area of ​​the substrate where plating is desired.

[0038] In the method for manufacturing an electric storage device according to one aspect of the present invention, a plurality of exposed portions may be formed on the first holding member in the second preparation step. This allows the power supply locations to the substrate to be dispersed, so that the plating process can be performed more uniformly.

[0039] In the method for manufacturing a power storage device according to one aspect of the present invention, in the second preparation step, an exposed portion is formed on the second clamping member, and in the plating step, current is supplied to the second clamping member having the exposed portion formed thereon. Thus, current can be supplied from the back side of the region of the substrate to be plated.

[0040] An electrolytic plating method according to one aspect of the present invention comprises: a first preparation step of preparing: a first clamping member, the entire surface of which is covered with insulation and provided with an opening; and a second clamping member, the entire surface of which is covered with insulation; a second preparation step of stripping the insulation coating from a portion of one of the first and second clamping members to form an exposed portion that exposes the conductive member of the one clamping member; and a plating treatment step of clamping a substrate by the first and second clamping members and immersing the substrate as a cathode in a plating solution in such a manner that the opening is arranged at an area of ​​the substrate where plating treatment is desired and the exposed portion is arranged at a portion of the substrate where current is desired to be supplied, thereby supplying current to the conductive member of one of the first and second clamping members where the exposed portion is formed.

[0041] However, in order to achieve cost reduction in the manufacture of power storage devices, it has been studied that at least a portion of the electrode plates use a steel plate that has been subjected to nickel plating. For example, in the case of nickel plating on a substrate, the following electrolytic plating method is used: the substrate to be plated and the metal nickel are placed in a plating solution stored in a plating tank, and a direct current is flowed in a manner that the substrate becomes a cathode (cathode) and the metal nickel becomes an anode (anode). In this electrolytic plating method, the substrate immersed in the plating solution is connected to the power supply above the plating solution, so the current supply part (voltage application part) in the substrate is limited to the top of the substrate. In this case, uneven current density will occur in the substrate, and the plating thickness will deviate. The optimal current supply part for making the plating thickness uniform varies depending on the plating treatment conditions, so there is a desire to easily change the current supply part to the substrate. Therefore, an aspect of the present invention is to provide an electrolytic plating process that can easily change the current supply part to the substrate that becomes the cathode when performing an electrolytic plating process.

[0042] In the electrolytic plating method, before the substrate is clamped by the first clamping member and the second clamping member, a power supply portion for supplying power to the substrate can be formed by a simple operation of peeling off a portion of the insulating coating from only one of the first clamping member and the second clamping member. The substrate in contact with the exposed portion can be energized by the clamping member formed with the exposed portion. Therefore, if the clamping members are configured in such a way that the exposed portion is configured in the portion of the substrate to which the current is desired to be supplied when the substrate is clamped by the first clamping member and the second clamping member, the substrate can receive the supply of current from the exposed portion. As described above, in order to form the power supply portion, only a portion of the insulating film of the clamping member is peeled off, so the power supply portion can be arbitrarily changed. As a result, the current supply portion can be easily changed for the substrate that becomes the cathode during the electrolytic plating process.

[0043] Effects of the Invention

[0044] According to one aspect of the present invention, the influence of the surface shape of a steel sheet on electrode performance can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a cross-sectional view schematically showing the power storage device according to the first embodiment.

[0046] Figure 2 (a) is Figure 1 An enlarged view of the edge of the collector and its surroundings. Figure 2 (b) is Figure 2 An enlarged view of the main part of (a).

[0047] Figure 3 (a) to (c) are schematic diagrams for explaining an example of a method for forming a plating layer on one surface of a current collector.

[0048] Figure 4 It is a graph showing the change in the average height of the protrusions of the base nickel plating layer with respect to the temperature of the nickel bath.

[0049] Figure 5 (a) is a photograph showing a part of the surface of the base nickel plating layer. Figure 5 (b) is a photograph showing a part of the cross section of the base nickel plating layer.

[0050] Figure 6 This is a photograph showing a part of the surface of the main nickel plating layer.

[0051] Figure 7 (a) is a photograph showing the surface of a steel plate. Figure 7 (b) is a photograph showing the surface of the current collector when only the main nickel plating layer is formed on the steel sheet. Figure 7 (c) is a photograph showing the surface of the current collector when a smooth plated layer is formed as a base nickel plated layer.

[0052] Figure 8 This is a photograph showing the surface of the current collector when the surface shape of the base nickel plating layer is set to a surface shape different from the surface shape of the steel plate.

[0053] Fig. 9 It is a schematic diagram illustrating the process of forming a base nickel plating layer on the surface of a steel sheet.

[0054] Fig.10 It is a graph showing the change in the average height of the protrusions with respect to the current density set in the electrolytic plating.

[0055] Fig.11(a) and Fig.11 (b) is a photograph showing a part of the surface of the main nickel plating layer.

[0056] Fig.12 This is a photograph showing a part of the surface of the main nickel plating layer.

[0057] Fig.13 (a) shows that the speed of the stirring element is set to 0 min. -1 A photograph of a portion of the surface of the primary nickel plating layer. Fig.13 (b) shows that the speed of the stirring element is set to 800 min -1 A photograph of a portion of the surface of the primary nickel plating layer.

[0058] Fig.14 The stirring speed is set to 200 min. -1 A photograph of a portion of the surface of the main nickel plating layer after electrolytic plating was performed.

[0059] Fig.15 It is a schematic diagram illustrating the process of forming a base nickel plating layer on the surface of a steel sheet.

[0060] Fig.16 It is a schematic diagram illustrating the process of forming a main nickel plating layer on the base nickel plating layer.

[0061] Fig.17 This is a cross-sectional view schematically showing a plating method according to one embodiment.

[0062] Fig.18 yes Fig.17 A side view of each of the first clamping member and the second clamping member, and a side view of the first clamping member and the second clamping member viewed from the metal material Fig.17 The first clamping member and the second clamping member are respective front views.

[0063] Fig.19 is a flow chart of an electrolytic plating method according to one embodiment.

[0064] Fig. 20 This is a cross-sectional view schematically showing a plating method according to another embodiment.

[0065] Fig.21 yes Fig. 20 A side view of each of the first clamping member and the second clamping member, and a side view of the first clamping member and the second clamping member viewed from the metal material Fig. 20 The first clamping member and the second clamping member are respective front views.

[0066] Fig. 22 (a) to (c) are enlarged cross-sectional views of the peripheral edge portion of the electrode according to the modified example. DETAILED DESCRIPTION

[0067] Hereinafter, preferred embodiments of a power storage device according to one aspect of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same elements or elements having the same functions are denoted by the same reference numerals, and repeated descriptions are omitted. Figure 1 , Figure 2 as well as Fig. 22 In FIG. 1 , an XYZ orthogonal coordinate system is shown for convenience of explanation.

[0068] Figure 1 1 is a cross-sectional view schematically showing an embodiment of a power storage device. The power storage device 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. The power storage device 1 is used as a battery for various vehicles such as a forklift, a hybrid vehicle, and an electric vehicle. The following describes, as an example, a case where the power storage device 1 is a nickel-hydrogen secondary battery.

[0069] The power storage device 1 is a bipolar battery including a stack 2 of bipolar electrodes (electrodes) 3. The power storage device 1 includes: the stack 2 of bipolar electrodes 3; a case 5 that holds the stack 2; and a restraint 6 that restrains the stack 2.

[0070] The stack 2 is formed by stacking a plurality of bipolar electrodes 3 along a first direction D1 with separators 7 interposed therebetween. The first direction D1 is here a direction along the Z-axis direction, and is hereinafter also referred to as the up-down direction or the stacking direction. For example, with a bipolar electrode 3 separated from a terminal member 25 described later as a reference, other bipolar electrodes 3 are disposed above and below the bipolar electrode 3 with separators 7 sandwiched therebetween. Each of the bipolar electrodes 3 includes: a current collector 11; a positive electrode layer 12 disposed on one surface 11a of the current collector 11; and a negative electrode layer 13 disposed on the other surface 11b of the current collector 11. The positive electrode layer 12 and the negative electrode layer 13 are respectively active material layers, and are disposed in at least the central portion M of the current collector 11. In the stack 2, the positive electrode layer 12 of one bipolar electrode 3 is opposite to the negative electrode layer 13 of one bipolar electrode 3 adjacent in the first direction D1, and the negative electrode layer 13 of one bipolar electrode 3 is opposite to the positive electrode layer 12 of another bipolar electrode adjacent in the first direction D1. The stack 2 has a plurality of resin spacers 4 for maintaining the spacing between adjacent bipolar electrodes 3. The resin spacers 4 are arranged along the peripheral portion 11c of the bipolar electrode 3 and are arranged to contact one surface of the bipolar electrode 3. The resin spacers 4 are formed, for example, by curing a resin arranged on the peripheral portion 11c. The resin before curing may be in a liquid state, a sheet state, or a gel state.

[0071] The collector 11 is a steel plate with nickel plating applied to the surface. As the steel plate, for example, cold-rolled steel plates (SPCC, etc.) specified in JIS G 3141:2005 can be cited. The thickness of the collector 11 can be, for example, not less than 0.1 μm and not more than 1000 μm. As the positive electrode active material constituting the positive electrode layer 12, for example, nickel hydroxide can be cited. As the negative electrode active material constituting the negative electrode layer 13, for example, a hydrogen storage alloy can be cited. The formation area of ​​the negative electrode layer 13 in the other side 11b of the collector 11 can also be larger than the formation area of ​​the positive electrode layer 12 in one side 11a of the collector 11. In addition, the nickel plating treatment will be described in detail later.

[0072] The peripheral portion 11c of the current collector 11 is an uncoated area to which the positive electrode active material and the negative electrode active material are not coated. The peripheral portion 11c is held in the shell 5 in a state of being buried in the inner wall 5a of the shell 5. The resin spacer 4 is disposed between one surface 11a of the peripheral portion 11c and the inner wall 5a. Thus, a space separated by the current collectors 11, 11 and the inner wall 5a of the shell 5 is formed between the current collectors 11, 11 adjacent to each other in the first direction D1. An electrolyte (not shown) such as an alkaline solution such as an aqueous potassium hydroxide solution is contained in the space. The electrolyte storage space formed between the bipolar electrodes 3 adjacent to each other in the first direction D1 is separated (sealed) in a liquid-tight manner from each other by the resin spacer 4.

[0073] At one stacking end (in the positive direction of the Z-axis direction) of the stack 2, a collector 11A having a negative electrode layer 13 only on one side is stacked. The collector 11A is arranged in such a way that the negative electrode layer 13 faces the positive electrode layer 12 of the uppermost bipolar electrode 3 via the separator 7. The collector 11A may be, for example, a steel plate that has been nickel-plated in the same manner as the collector 11, or a metal foil such as nickel foil. In addition, at the other stacking end (in the negative direction of the Z-axis direction) of the stack 2, a collector 11B having only a positive electrode layer 12 is stacked. The collector 11B is arranged in such a way that the positive electrode layer 12 faces the negative electrode layer 13 of the lowermost bipolar electrode 3 via the separator 7. The collector 11B may be, for example, a steel plate that has been nickel-plated in the same manner as the collector 11, or a metal foil such as nickel foil. The edges of the current collectors 11A and 11B are held in the case 5 in a state buried in the inner wall 5a of the case 5, similarly to the current collector 11 of the bipolar electrode 3. The resin spacer 4 is interposed between one surface of the edge of the current collectors 11A and 11B and the inner wall 5a. The current collectors 11A and 11B may be formed thicker than the current collector 11 of the bipolar electrode 3.

[0074] The separator 7 is, for example, an insulating material formed in a sheet shape. As the forming material of the separator, a porous film including a polyolefin resin such as polyethylene (PE) and polypropylene (PP), a woven fabric or non-woven fabric including polypropylene, etc., etc. can be exemplified. In addition, the separator 7 can also be reinforced with a vinylidene fluoride resin compound, etc. In addition, the separator 7 is not limited to a sheet shape, and a bag-shaped insulating material can also be used.

[0075] The housing 5 is formed into a rectangular cylindrical shape by injection molding using an insulating resin, for example. Examples of the resin material constituting the housing 5 include polypropylene (PP), polyphenylene sulfide (PPS), modified polyphenylene ether (modified PPE), and modified polyphenylene sulfide (modified PPS). The housing 5 is a member that surrounds the side surface 2a of the stacked body 2 formed by stacking the bipolar electrodes 3 and holds it.

[0076] The constraint body 6 includes a pair of constraint plates 21, 21 and connecting members (bolts 22 and nuts 23) connecting the constraint plates 21, 21 to each other. The constraint plate 21 is formed into a flat plate shape by a metal such as iron. At the edge of the constraint plate 21, an insertion hole 21a for inserting the bolt 22 is arranged at a position closer to the outside than the shell 5. The inner peripheral surface of the insertion hole 21a and the bolt seat surface in the constraint body 6 are insulated. In addition, on one side of the constraint plate 21, a terminal member 25 (negative terminal member 25A, positive terminal member 25B) is combined with an insulating member 24. As a forming material of the insulating member 24 between the constraint plate 21 and the terminal member 25, for example, a fluorine-based resin or a polyethylene resin can be cited.

[0077] One constraint plate 21 is located at one side of the case 5 in the first direction D1. One constraint plate 21 abuts against one end surface of the case 5 in such a manner that the negative terminal member 25A abuts against the collector 11A on the inner side of the case 5. The other constraint plate 21 is located at the other side of the case 5 in the first direction D1. The other constraint plate 21 abuts against the other end surface of the case 5 in such a manner that the positive terminal member 25B abuts against the collector 11B on the inner side of the case 5. The bolt 22 passes through the insertion hole 21a from the side of one constraint plate 21 toward the side of the other constraint plate 21, for example, and a nut 23 is screwed on the tip of the bolt 22 protruding from the other constraint plate 21.

[0078] Thus, the stack 2, the current collectors 11A, 11B, and the case 5 are clamped and unitized, and a restraining load along the first direction D1 is applied to the stack 2. In addition, the negative terminal member 25A is arranged between one restraining plate 21 and the stack 2, and the positive terminal member 25B is arranged between the other restraining plate 21 and the stack 2. The lead portion 26 is connected to the negative terminal member 25A. The lead portion 27 is connected to the positive terminal member 25B. The lead portion 26 and the lead portion 27 enable the charge and discharge of the power storage device 1.

[0079] Next, refer to Figure 2 (a) and Figure 2 (b) describes the structure of the current collector 11 in the above-mentioned power storage device 1 and the configuration of the junction between the current collectors 11 , 11A, 11B and the resin separator 4 . Figure 2 (a) is Figure 1 An enlarged view of the edge of the current collector and its surroundings. Figure 2 (b) is Figure 2 (a) is an enlarged view of a main part. In the following description, the current collector 11 will be described. The current collectors 11A and 11B may have the same structure as the current collector 11, or may not have the same structure as the current collector 11.

[0080] like Figure 2 As shown in (a), a plating layer 30 covering one surface S1 of the steel sheet S is formed on the peripheral portion 11c of the collector 11. Therefore, on the peripheral portion 11c of the collector 11, the resin spacer 4 is arranged in contact with the plating layer 30. The plating layer 30 is provided to ensure the strength and liquid tightness between the steel sheet S and the resin spacer 4 and to increase the surface area of ​​the collector 11. The plating layer 30 can be formed on the surface of the steel sheet S by subjecting the steel sheet S constituting the collector 11 to an electrolytic nickel plating treatment. Therefore, the plating layer 30 is equivalent to a nickel layer formed by electrolytic plating. The thickness of the plating layer 30 is set to, for example, not less than 5 μm and not more than 20 μm.

[0081] like Figure 2 (a) and Figure 2 As shown in (b), the plating layer 30 includes a base nickel plating layer 31 provided on one surface S1 of the steel sheet S and a main nickel plating layer 32 provided on the base nickel plating layer 31. The base nickel plating layer 31 and the main nickel plating layer 32 are formed by electrolytic plating under different conditions.

[0082] The base nickel plating layer 31 is an electrolytic plating layer provided on one surface S1 of the steel sheet S along the second direction D2 intersecting the first direction D1. The second direction D2 is equivalent to the direction along the XY plane or the extension direction of one surface S1. Therefore, the second direction D2 may not necessarily be orthogonal to the first direction D1. The thickness of the base nickel plating layer 31 is, for example, not less than 0.5 μm and not more than 2 μm. Preferably, the base nickel plating layer 31 covers the entire surface S1 in the peripheral portion 11c. In this case, it is not easy to form pinholes, etc. in the plating layer 30, so the occurrence of leakage current can be suppressed. The surface shape of the base nickel plating layer 31 is different from the shape of one surface S1. Specifically, the base nickel plating layer 31 has a plurality of protrusions 33 protruding along the first direction D1. Therefore, the surface shape of the base nickel plating layer 31 is not along one surface S1 of the steel sheet S, and is rougher than the surface shape of one surface S1 of the steel sheet S. Therefore, the base nickel plating layer 31 is set to be different from the smooth plating layer. The smooth plating layer is a plating layer having a surface shape that follows the surface of the object to be plated.

[0083] A plurality of protrusions 33 are irregularly provided along the second direction D2. When the thickness of the base nickel plating layer 31 is about 1 μm or more, the average height of the protrusions 33 may be, for example, 0.4 μm or more and less than half the thickness of the base nickel plating layer 31. In this case, the shape of the main nickel plating layer 32 can be made good. The average height of the protrusions 33 is measured, for example, by a microscope using a laser confocal optical system.

[0084] The main nickel plating layer 32 is an electrolytic plating layer that sets the base nickel plating layer 31 as the film-forming surface, and has a larger surface roughness than the base nickel plating layer 31. The surface roughness of the base nickel plating layer 31 and the main nickel plating layer 32 are respectively expressed by the arithmetic mean roughness Ra specified in JIS B 0601:2013 (or ISO 4287:1997, Amd.1:2009). The surface roughness of the main nickel plating layer 32 is, for example, 1.5 μm to 6.0 μm, which is 1.5 times to 60.0 times that of the base nickel plating layer 31. In this case, not only can the generation of pinholes in the plating layer 30 be suppressed, but also the surface area of ​​the main nickel plating layer 32 can be increased. The thickness of the main nickel plating layer 32 is, for example, 5 μm to 20 μm. In the peripheral portion 11c of the collector 11, the main nickel plating layer 32 does not necessarily have to be formed in a manner that covers the entire surface of the base nickel plating layer 31. For example, the main nickel plating layer 32 may be a collection of a plurality of protrusions 34 protruding from the base nickel plating layer 31 in the first direction D1. In this case, the main nickel plating layer 32 is also referred to as a roughened plating layer. The plurality of protrusions 34 are each formed to have a portion in contact with the corresponding convex portion 33 as a base end 34a and to reach a tip end 34b along the first direction D1.

[0085] At least a portion of the protrusions 34 among the plurality of protrusions 34 overlap with a plurality of nickel crystals, for example, in a roughly spherical shape. These nickel crystals are a plurality of deposited metals (imparted substances) formed by electrolytic plating. Such deposited metals overlap with each other, thereby forming an enlarged portion 34c whose length dimension of the protrusion 34 in the second direction D2 is larger than the length dimension of the base end 34a in the second direction D2. That is, at least a portion of the protrusions 34 are in a rough head shape in which the top becomes thicker as it goes from the base end 34a side to the top end 34b side. The position of the enlarged portion 34c in the protrusion 34 may not necessarily be the top end 34b, but at least be located at a position closer to the top end 34b side than the base end 34a. In other words, in the protrusion 34 in a rough head shape, the portion with the largest length dimension in the second direction D2 may not be the top end 34b, but may be located at a position other than the base end 34a. The position of the enlarged portion 34c in the protrusion 34 may also be different in each protrusion 34 according to the overlapping form of the deposited metal.

[0086] A portion 4a of the resin spacer 4 is interposed between two adjacent protrusions 34 among the plurality of protrusions 34, at least one of which has a rough head shape. For example, before the resin constituting the resin spacer 4 is cured, a portion of the resin is interposed between the protrusions 34. Then, by curing the entire resin, a portion 4a of the resin spacer 4 is interposed between the protrusions 34. Thus, the two adjacent protrusions 34 restrict the movement of a portion 4a of the resin spacer 4 interposed therebetween in a direction away from the base end 34a. In other words, the cross-sectional shape between the adjacent protrusions 34 becomes an undercut shape that has an anchoring effect.

[0087] The average height of the protrusions 34 is, for example, 15 μm or more and 30 μm or less. By setting the average height of the protrusions 34 to be 15 μm or more, a good anchoring effect is achieved for the portion 4a of the resin spacer 4 between two adjacent protrusions 34. By setting the average height of the protrusions 34 to be 30 μm or less, the breakage of the protrusions 34 can be well suppressed. The average height of the protrusions 34 is measured, for example, using a microscope using a laser confocal optical system.

[0088] When viewed from above (i.e., when viewed along the first direction D1), the number of protrusions 34 per unit area of ​​the main nickel plating layer 32 is, for example, 2,500 or more and 7,000 or less. By setting the number of protrusions 34 to 2,500 or more, the surface area of ​​the main nickel plating layer 32 can be sufficiently ensured. By setting the number of protrusions 34 to 7,000 or less, contact between adjacent protrusions 34 can be suppressed. In one embodiment, the unit area is 1 mm 2The number of protrusions 34 per unit area of ​​the main nickel plating layer 32 is calculated from the average length RSm of the roughness curve element specified in JIS B 0601:2013 (or ISO 4287:1997, Amd. 1:2009), for example.

[0089] In the central portion M of the bipolar electrode 3 (see Figure 1 ), a plating layer 30 covering one surface S1 of the steel sheet S is formed. The central portion M is bonded to the positive electrode active material of the positive electrode layer 12 via the plating layer 30. That is, in one embodiment, the plating layer 30 is continuously formed on one surface S1 of the steel sheet S from the peripheral portion 11c to the central portion M. More specifically, the base nickel plating layer 31 covers the entire surface S1 of the steel sheet S. On the other hand, the main nickel plating layer 32 may not cover the entire surface of the base nickel plating layer 31.

[0090] The plating layer 30 covers the surface on one side (positive direction of the Z-axis direction) of the first direction D1 in any of the plurality of steel plates S. The resin spacer 4 is arranged across the plating layer 30 in any of the plurality of current collectors 11. Thus, in the bipolar electrodes 3 adjacent to each other in the first direction D1, the resin spacer 4 located on one surface 11a of the current collector 11 is opposite to the other surface 11b of the current collector 11 in the first direction D1. That is, in the adjacent bipolar electrodes 3, the one surface 11a of the current collector 11 and the other surface 11b of the current collector 11 are separated from each other by the resin spacer 4 as a resin member. Therefore, in the adjacent bipolar electrodes 3, the insulation between the one surface 11a of the current collector 11 and the other surface 11b of the current collector 11 is ensured by the resin spacer 4.

[0091] Next, use Figure 3 An example of a method for forming the plating layer 30 is described with reference to (a) to (c). Figure 3 (a) to (c) are schematic diagrams for explaining an example of a method for forming a plating layer on one surface of a current collector. Figure 3 In (b) and (c), the specific surface shapes of the base nickel plating layer 31 and the main nickel plating layer 32 are omitted.

[0092] First, if Figure 3 As shown in (a) of FIG. 1 , a steel sheet S constituting the current collector 11 is prepared. Next, as Figure 3As shown in (b), on the surface S1 of the steel plate S serving as the current collector 11, a base nickel plating layer 31 having a surface shape different from the surface shape of the steel plate S is formed. The base nickel plating layer 31 is formed by electrolytically plating the steel plate S. In the electrolytic plating, for example, a nickel bath is used in which the nickel concentration is set to be between 0.5 mol / L and 2.0 mol / L and the temperature is set to be between 40°C and 65°C. A nickel bath refers to an electrolyte in which nickel cations are present, such as a nickel chloride solution, a nickel sulfate solution, and the like. By setting the nickel concentration of the nickel bath to be between 0.5 mol / L and 2.0 mol / L, a plating layer can be efficiently formed. In addition, by setting the temperature of the nickel bath to be between 40°C and 65°C, the average height of the protrusions 33 provided on the base nickel plating layer 31 can be well controlled.

[0093] When electrolytic plating is performed to form the base nickel plating layer 31, for example, at a current density of 0.5 A / dm 2 Above 5.0A / dm 2 The steel sheet S was immersed in the nickel bath for a period of 150 seconds to 2,400 seconds under the following conditions. The current density in the electrolytic plating was set to 0.5 A / dm 2 Above 5.0A / dm 2 Hereby, the base nickel plating layer 31 can be prevented from becoming a smooth plating layer. Moreover, the convex portion 33 formed on the base nickel plating layer 31 can be suppressed from being needle-shaped (or whisker-shaped). In addition, by immersing the steel sheet S in the nickel bath for a period of 150 seconds to 2,400 seconds, the thickness of the base nickel plating layer 31 can be well set.

[0094] The conditions that are particularly important when forming the base nickel plating layer 31 are the temperature and current density of the nickel bath. Therefore, when either the temperature and current density of the nickel bath are within the above range, the nickel concentration of the nickel bath and the time for which the steel sheet S is immersed may not necessarily be within the above range.

[0095] Figure 4 Graph showing the change in the average height of the protrusions of the base nickel plating layer relative to the temperature of the nickel bath. Figure 4 In FIG. 5 , the vertical axis shows the average height of the protrusions, and the horizontal axis shows the temperature of the nickel bath. The solid line 51 shows the current density set to 1.0 A / dm 2 The average height of the protrusions changes with respect to the temperature of the nickel bath when the current density is set to 0.5 A / dm 2 The change in the average height of the protrusions relative to the temperature of the nickel bath when the current density is set to 5A / dm 2 The average height of the protrusions changes with respect to the temperature of the nickel bath. For example, when the current density is set to 1.0 A / dm 2In the case of , if the temperature of the nickel bath is 40°C to 65°C, the average height of the protrusions becomes 0.4 μm or more. In addition, when the temperature of the nickel bath is 50°C, the average height of the protrusions is the maximum. On the other hand, in any case of a current density that is too low or a current density that is too high, the average height of the protrusions tends to be less than 0.4 μm regardless of the temperature of the nickel bath.

[0096] Here, use Figure 5 (a) and Figure 5 (b) shows the surface shape of the base nickel plating layer actually formed on the steel plate. Figure 5 (a) is a photograph showing a portion of the surface of the base nickel plating layer, Figure 5 (b) is a photograph showing a part of the cross section of the base nickel plating layer. Figure 5 (a) and Figure 5 The base nickel plating layer 31 shown in (b) is obtained by setting the current density to 1 A / dm 2 The steel sheet S is immersed in a nickel chloride bath at a temperature of 50°C and a nickel concentration of 1 mol / L for 300 seconds under the conditions of Figure 5 As shown in (a), a plurality of protrusions 33 are provided on the surface of the base nickel plating layer 31. Figure 5 As shown in (b), the surface shape of the base nickel plating layer 31 is greatly different from the surface shape of the steel sheet S. This base nickel plating layer 31 is provided with many protrusions 33, and has a surface shape greatly different from the surface shape of the steel sheet S. In addition, the surface roughness Ra of the base nickel plating layer 31 is, for example, not less than 0.1 μm and not more than 1.0 μm.

[0097] Next, if Figure 3 As shown in (c), a main nickel plating layer 32 including a plurality of protrusions 34 and having a surface roughness greater than that of the base nickel plating layer 31 is formed on the base nickel plating layer 31 (see Figure 2 (b)). Thus, a collector 11 having a steel sheet S and a plating layer 30 having a base nickel plating layer 31 and a main nickel plating layer 32 can be obtained. The main nickel plating layer 32 is formed by electrolytic plating the steel sheet S on which the base nickel plating layer 31 is formed. In the electrolytic plating, for example, a Watt bath is used in which the nickel concentration is set to be greater than 0.15 mol / L and less than 0.30 mol / L and the temperature is set to be greater than 30°C and less than 60°C. A Watt bath refers to an electrolyte having nickel sulfate, nickel chloride and boric acid as main components. By setting the nickel concentration of the Watt bath to be greater than 0.15 mol / L and less than 0.30 mol / L, a protrusion 34 in the shape of a rough head can be well formed. In addition, by setting the temperature of the Watt bath to be greater than 30°C and less than 60°C, the average height of the rough head shape can be well controlled.

[0098] When electrolytic plating is performed to form the main nickel plating layer 32, for example, at a current density of 30 A / dm 2 Above 50A / dm 2 The steel sheet S was immersed in the nickel bath for 30 seconds to 60 seconds under the following conditions. The current density in the electrolytic plating was set to 30 A / dm 2 Above 50A / dm 2 Then, the protrusions 34 having a rough head shape can be formed satisfactorily. In addition, by immersing the steel sheet S in the Watts bath for a period of 30 seconds to 60 seconds, the thickness of the main nickel plating layer 32 can be set satisfactorily.

[0099] The conditions that are particularly important when forming the main nickel plating layer 32 are the nickel concentration and current density of the Watt bath. Therefore, when either the nickel concentration and current density of the Watt bath are within the above range, the temperature of the Watt bath and the time for which the steel sheet S is immersed may not necessarily be within the above range.

[0100] Here, use Figure 6 The surface shape of the main nickel plating layer actually formed is shown. Figure 6 This is a photograph showing a part of the surface of the main nickel plating layer. Figure 6 The main nickel plating layer 32 shown is formed by using a Watt bath having a temperature of 30° C. and a nickel concentration of 0.2 mol / L, and setting the current density to 40 A / dm 2 The steel plate having the base nickel plating layer is immersed for 40 seconds under the conditions of Figure 6 As shown, a plurality of protrusions 34 with a rough head shape whose top ends become thicker as they go from the base end side to the top end side are confirmed. In addition, a plurality of nickel crystals overlap on the surfaces of these protrusions 34. Therefore, the main nickel plating layer 32 composed of these protrusions 34 is significantly roughened compared with the base nickel plating layer 31. The surface roughness of the main nickel plating layer 32 is significantly greater than that of the base nickel plating layer 31, and its surface roughness Ra is, for example, not less than 1.5 μm and not more than 6.0 μm.

[0101] Furthermore, by appropriately providing an active material layer on the current collector 11 having the plating layer 30 obtained by the above-mentioned formation method, the bipolar electrode 3 can be formed. Then, by appropriately stacking a plurality of bipolar electrodes 3 and separators 7, a stacked body 2 can be formed. By using this stacked body 2, a Figure 1 The electricity storage device 1 shown. A method for manufacturing the electricity storage device 1 using the bipolar electrode 3 can appropriately use a known method.

[0102] Next, use Figure 7 (a) to (c) and Figure 8 The operation and effects of the power storage device 1 according to one embodiment will be described. Figure 7 (a) is a photograph showing the surface of a steel plate. Figure 7 (b) is a photograph showing the surface of the current collector when only the main nickel plating layer is formed on the steel sheet. Figure 7 (c) is a photograph showing the surface of the current collector when a smooth plated layer is formed as a base nickel plated layer. Figure 8 This is a photograph showing the surface of the current collector when the surface shape of the base nickel plating layer is set to a surface shape different from the surface shape of the steel plate.

[0103] like Figure 7 As shown in (a), there are damages on the surface of the steel plate caused during manufacturing. Therefore, the surface of the steel plate is provided with unevenness. If the base nickel plating layer is not formed on the steel plate, it will be as follows Figure 7 As shown in (b), there is a tendency that the surface of the steel plate is not completely plated. That is, many pinholes are provided in the plating layer. In this case, the leakage current in the collector becomes larger, and the performance of the electrode including the collector is significantly reduced. In addition, in the case where a smooth plating layer is formed on the surface of the steel plate as a base nickel plating layer, it is not easy to provide pinholes in the plating layer. The performance of the electrode including the collector provided with such a base nickel plating layer tends to be better than the performance of the electrode including the collector without the base nickel plating layer. However, as Figure 7 As shown in (c), there is a tendency for large irregularities to remain on the surface of the main nickel plating layer. In the area where such irregularities are provided, there is a tendency for the sealing provided by the resin spacer to be reduced and for leakage current to flow easily. Therefore, even in the case where a smooth plated layer is formed on the surface of the steel plate as a base nickel plating layer, there is a possibility that the electrode performance is reduced. In contrast, in the case where the surface shape of the base nickel plating layer is set to a surface shape different from the surface shape of the steel plate, as in Figure 8 As shown, the surface of the current collector is completely covered with the plating layer and does not have large irregularities. The performance of the electrode including such a current collector is not easily affected by the surface shape of the steel sheet.

[0104] As described above, in the power storage device 1 manufactured by the manufacturing method of one embodiment, the base nickel plating layer 31 is provided on the surface of the steel sheet S, and the main nickel plating layer 32 is provided on the base nickel plating layer 31. Therefore, the shape of the main nickel plating layer 32 located on the surface side of the plating layer 30 is not easily affected by the surface shape of the steel sheet S. Therefore, according to the power storage device 1, the influence of the surface shape of the steel sheet S on the electrode performance can be suppressed. In addition, the surface roughness of the main nickel plating layer 32 is greater than the surface roughness of the base nickel plating layer 31. As a result, the surface area of ​​the plating layer 30 becomes larger, and the heat dissipation of the electrode can be improved.

[0105] Alternatively, the power storage device 1 includes a resin spacer 4 disposed along the peripheral portion 11c of the bipolar electrode 3 and in contact with the plated layer 30, the plated layer 30 having a plurality of protrusions 34 protruding in a direction intersecting with the extending direction of the surface S1 of the steel sheet S, at least a portion of the plurality of protrusions 34 having a rough-headed shape with the tip becoming thicker as it goes from the base end 34a side to the tip 34b side, and a portion 4a of the resin spacer 4 is interposed between two adjacent protrusions 34 among the plurality of protrusions 34 and at least one of the protrusions 34 having a rough-headed shape from the tip 34b side to the base end 34a side. In this case, movement of the portion 4a of the resin spacer 4 interposed between the two adjacent protrusions 34 in a direction away from the base end 34a of the protrusion 34 can be restricted. Therefore, peeling of the resin spacer 4 from the plated layer 30 can be suppressed.

[0106] The average height of the plurality of protrusions 34 may be 15 μm or more and 30 μm or less. In this case, not only the breakage of the protrusions 34 can be suppressed, but also the peeling of the resin spacer 4 from the plating layer 30 can be suppressed satisfactorily.

[0107] Alternatively, a plurality of nickel crystals may be overlapped on at least a portion of the plurality of protrusions 34. In this case, a plurality of nickel crystals may be overlapped on the surface of the protrusion 34. Therefore, a portion 4a of the resin spacer 4 engages with the recessed portion on the surface of the protrusion 34, thereby effectively preventing the resin spacer 4 from peeling off from the plating layer 30.

[0108] It can also be that at a current density of 0.5A / dm 2 Above 5.0A / dm 2 Under the following conditions, the steel sheet S is immersed in a nickel bath in which the nickel concentration is set to 0.5 mol / L or more and 2.0 mol / L or less, thereby forming a base nickel plating layer 31 having a plurality of protrusions 33 on the surface of the steel sheet S. In this case, the average height and shape of the plurality of protrusions 33 provided on the base nickel plating layer 31 can be well controlled. Therefore, nickel is easy to grow from the protrusions 33, and the shape of the main nickel plating layer 32 is further less susceptible to the surface shape of the steel sheet S.

[0109] The steel sheet S may be immersed in the nickel bath for 150 to 2,400 seconds under the condition that the temperature of the nickel bath is set to 40 to 65° C. In this case, the average height and shape of the plurality of projections 33 can be more well controlled.

[0110] Below, use Fig. 9 A specific example of the step of forming a base nickel plating layer on the surface of a steel sheet will be described. Fig. 9 Schematic diagram illustrating the process of forming a base nickel plating layer on the surface of a steel plate. Fig. 9As shown, after the steel plate S wound into a roll by the roller DR2 is pulled out and conveyed along the surface of at least the lower half of the roller DR1, the steel plate S is wound onto the roller DR3. At this time, the lower part of the roller DR1 and the anode 60 are immersed in the electrolyte L1 containing nickel cations. Thus, the steel plate S in contact with the lower surface of the roller DR1 is immersed in the electrolyte L1. And, during the conveyance of the steel plate S, a predetermined current flows between the roller DR1 and the anode 60. As a result, nickel is precipitated on the surface S1 of the steel plate S immersed in the electrolyte L1 (the surface of the steel plate S located on the opposite side of the surface in contact with the surface of the roller DR1), and a base nickel plating layer 31 having a protrusion 33 is formed on the surface S1 of the steel plate S.

[0111] In addition, the steel sheet S provided with the base nickel plating layer 31 and wound on the drum DR3 can be used. Fig. 9 The method exemplified in the above also forms the main nickel plating layer 32 having the protrusions 34. When the main nickel plating layer 32 is formed, current concentration occurs at the protrusions 33, so nickel is selectively precipitated so that the protrusions 33 become the base ends 34a, and a plurality of protrusions 34 can be selectively formed. By this method, the current collector 11 having the plating layer 30 can also be formed.

[0112] Next, in the configuration of the power storage device 1 similar to that described above, the relationship between the current density set in the electrolytic plating and the average height of the protrusions will be described.

[0113] Fig.10 is a graph showing the change in the average height of the protrusions relative to the current density set in the electrolytic plating. Fig.10 In the figure, the vertical axis shows the average height of the protrusions, and the horizontal axis shows the current density. The solid line 151 shows the change in the average height of the protrusions relative to the current density when the nickel concentration of the Watt bath is set to 0.2 mol / L. The dotted line 152 shows the change in the average height of the protrusions relative to the current density when the nickel concentration of the Watt bath is set to 0.15 mol / L. The single-point dashed line 153 shows the change in the average height of the protrusions relative to the current density when the nickel concentration of the Watt bath is set to 0.3 mol / L. For example, when the current density is set to 25 A / dm 2 When the nickel concentration of the Watt bath is less than 0.3 mol / L, the average height of the protrusions is 15 μm to 30 μm. 2 When the nickel concentration of the Watt bath is greater than 0.15 mol / L and less than 0.2 mol / L, the average height of the protrusions is also greater than 15 μm and less than 30 μm. Fig.10 The data shown were obtained with the Watts bath set at 30°C.

[0114] Here, use Fig.11 (a) Fig.11 (b) and Fig.12 The surface shape of the main nickel plating layer actually formed is shown. Fig.11 (a) Fig.11 (b) and Fig.12 Each is a photograph showing a part of the surface of the main nickel plating layer. Fig.11 The main nickel plating layer shown in (a) is formed by using a Watt bath at a temperature of 30°C and a nickel concentration of 0.3 mol / L, and at a current density of 40 A / dm 2 The steel plate having the base nickel plating layer is immersed for 40 seconds under the conditions of. Fig.11 The main nickel plating layer shown in (b) is formed by using a Watt bath at a temperature of 30°C and a nickel concentration of 0.2 mol / L, and at a current density of 20 A / dm 2 The steel plate having the base nickel plating layer is immersed for 80 seconds under the conditions of. Fig.12 The main nickel plating layer shown was produced by using a Watt bath at a temperature of 30°C and a nickel concentration of 0.2 mol / L at a current density of 40 A / dm 2 The steel plate having the base nickel plating layer is immersed for 40 seconds under the conditions of Fig.11 (a) Fig.11 (b) and Fig.12 The hollow in the center portion shows a portion processed by a FIB device (FIB: Focused Ion Beam).

[0115] Fig.11 The main nickel plating layer shown in (a) includes a plurality of nickel crystals that are roughly spherical. In addition, no protrusions in the shape of rough heads are provided on the main nickel plating layer. It is presumed that this is due to the excessive nickel concentration in the Watt bath. In addition, a plurality of nickel crystals aggregate in a manner that fills the gap. In this case, the gap formed by adjacent nickel crystals is narrow, and thus it is difficult for the resin to enter the gap. Therefore, when using a Fig.11 When a bipolar electrode is produced from a current collector having a main nickel plating layer as shown in (a), the sealing property of the resin spacer in the peripheral portion tends to be weakened. In addition, the surface area of ​​the main nickel plating layer may be insufficient.

[0116] Fig.11 The plating layer shown in (b) includes irregularly arranged protrusions. It can be said that some of these protrusions have a rough head shape with the tip becoming thicker as it goes from the base end side to the tip side. In addition, it can be said that nickel crystals overlap on some of the protrusions. However, most of the protrusions have a thin head shape. In addition, the average height of the protrusions is less than 15μm. It is speculated that this is because the set current density is too low. Therefore, when using a Fig.11When a bipolar electrode is manufactured from a collector having a main nickel-plated layer as shown in (b), the sealing performance of the resin spacer in the peripheral portion is better than that of Fig.11 On the other hand, the surface area of ​​the main nickel plating layer may still be insufficient.

[0117] Fig.12 The main nickel plating layer shown is Fig.11 (b) also includes irregularly arranged protrusions. Most of these protrusions are in a rough head shape with the tip becoming thicker as it goes from the base end to the tip end. In addition, it can be confirmed that a plurality of nickel crystals overlap on the surface of these protrusions. Moreover, the average height of the arranged protrusions is not less than 15 μm and not more than 30 μm. Therefore, when using a protrusion having Fig.12 When a bipolar electrode is produced from a current collector having a main nickel plating layer as shown above, the sealing property of the resin spacer in the peripheral portion tends to be particularly strong, and the surface area of ​​the main nickel plating layer is also sufficient.

[0118] Fig.11 (a) Fig.11 (b) and Fig.12 Any of the main nickel-plated layers including the protrusions shown is significantly coarser than the base nickel-plated layer. Therefore, the surface roughness of the main nickel-plated layer is significantly greater than that of the base nickel-plated layer, and is significantly coarser than the base nickel-plated layer 31. The surface roughness of the main nickel-plated layer 32 is significantly greater than that of the base nickel-plated layer 31, and its surface roughness Ra is, for example, not less than 1.5 μm and not more than 6.0 μm.

[0119] When the main nickel plating layer 32 is formed by placing the steel sheet S formed with the base nickel plating layer 31 in a Watt bath, it is preferred to use a stirring member to stir the Watt bath. As a result, nickel cations can be well supplied to the surface of the base nickel plating layer 31, so there is a tendency to be able to well control the shape of the main nickel plating layer 32 (for example, the density of the main nickel plating layer 32). The stirring member can be in the shape of a rod, a plate, or a propeller. The rotation speed of the stirring member is, for example, 0 min -1 Above 600min -1 By making the stirring speed 0min -1 Above 600min -1 The number of protrusions 34 constituting the main nickel plating layer 32 per unit area can be well controlled. The rotation speed of the stirring element can also be 200 min. -1 Above 600min -1 In addition, the lower limit of the rotation speed of the stirring element may also be greater than 0min -1 .

[0120] Here, use Fig.13 (a) Fig.13 (b) and Fig.14 To illustrate the change in the number of protrusions relative to the rotation speed of the stirring element. Fig.13 (a) shows that the speed of the stirring element is set to 0 min. -1 A photograph of a portion of the surface of the primary nickel plating layer. Fig.13 (b) shows that the speed of the stirring element is set to 800 min -1 A photograph of a portion of the surface of the primary nickel plating layer. Fig.14 The stirring speed is set to 200 min. -1 A photograph of a portion of the surface of the main nickel plating layer after electrolytic plating was performed.

[0121] When the stirring speed is too low, Fig.13 As shown in (a), the number of protrusions constituting the main nickel plating layer decreases. That is, the number of protrusions per unit area is sometimes too small. It is speculated that this is due to insufficient nickel cations supplied to the surface of the base nickel plating layer. In this case, the surface area of ​​the plating layer may be insufficient. In addition, when the rotation speed of the stirring element is too high, such as Fig.13 As shown in (b), the protrusions constituting the main nickel plating layer are excessively formed. That is, the protrusions are excessively formed per unit area. It is speculated that this is due to the excessive supply of nickel cations to the surface of the base nickel plating layer. At this time, it is difficult for the resin to enter between two adjacent protrusions, so the sealing of the resin spacer tends to be insufficient. In contrast, by appropriately setting the rotation speed of the stirring member, as shown in FIG. Fig.14 As shown, the number of protrusions per unit area can be well controlled.

[0122] The speed of the stirring element is 0 min. -1 Above 600min -1 In the following cases, the relative speed between the base nickel plating layer 31 and the Watt bath is, for example, 0 m / s or more and 1.0 m / s or less. The relative speed is the difference between the speed of the top end of the stirring member and the base nickel plating layer 31 at rest, and is calculated, for example, by multiplying the circumference obtained based on the rotation trajectory of the top end of the stirring member by the rotation speed (i.e., circumference × rotation speed). In addition, the rotation direction of the stirring member is not particularly limited, and the rotation speed of the stirring member may not be fixed. The stirring member may also rotate intermittently.

[0123] The Watt bath may flow without using the above-mentioned stirring member. Moreover, the steel plate S formed with the base nickel plating layer 31 may also move in the Watt bath. In these cases, nickel cations are also well supplied to the base nickel plating layer 31, so there is a tendency to be able to well control the shape of the main nickel plating layer 32. In the case where at least one of the flow of the Watt bath and the movement of the steel plate S occurs, the moving speed of the steel plate S relative to the Watt bath is, for example, less than 1.0 m / s. In addition, the movement of the steel plate S can be achieved, for example, by transporting the steel plate S using a transporting machine or the like.

[0124] Furthermore, by appropriately providing an active material layer on the current collector 11 having the plating layer 30 obtained by the above-mentioned formation method, the bipolar electrode 3 can be formed. Then, by appropriately stacking a plurality of bipolar electrodes 3 and separators 7, a stacked body 2 can be formed. By using this stacked body 2, a Figure 1 The electricity storage device 1 shown. A method for manufacturing the electricity storage device 1 using the bipolar electrode 3 can appropriately use a known method.

[0125] As described above, in the power storage device 1 manufactured by the manufacturing method of one embodiment, the plating layer 30 includes a main nickel plating layer 32 having a plurality of protrusions 34 protruding along the second direction D2. Therefore, the surface area of ​​the main nickel plating layer 32 provided on the surface S1 side is larger than the surface area of ​​the plating layer only along the surface shape of the steel sheet S. Moreover, at least a part of the protrusions 34 among the plurality of protrusions 34 is in a rough head shape in which the top becomes thicker as it goes from the base end 34a side to the top end 34b side. The area of ​​the top of the protrusion 34 in the rough head shape is larger than the area of ​​the top of the protrusion in the thin head shape that is usually provided. Therefore, according to the above-mentioned power storage device 1, it is possible to have a bipolar electrode 3 that includes a steel sheet S and has a sufficient surface area.

[0126] Alternatively, the power storage device 1 may include a resin spacer 4 disposed along the peripheral portion 11c of the bipolar electrode 3 and in contact with the plating layer 30, and a portion 4a of the resin spacer 4 is interposed between two adjacent protrusions 34 of the plurality of protrusions 34 from the tip 34b side to the base end 34a side, the two protrusions 34 being at least one of the protrusions 34 having a rough head shape. In this case, the portion 4a of the resin spacer 4 interposed between the adjacent protrusions 34 is restricted from moving in a direction away from the base end 34a. Therefore, it is possible to suppress the resin spacer 4 from peeling off from the plating layer 30.

[0127] The average height of the plurality of protrusions 34 may be 15 μm or more and 30 μm or less. In this case, it is possible to suppress breakage of the protrusions 34 and to ensure a sufficient surface area of ​​the plating layer 30 .

[0128] A plurality of nickel crystals may be overlapped on at least a portion of the plurality of protrusions 34. In this case, projections and depressions are formed on the surface of the protrusion 34 on which the plurality of nickel crystals are overlapped, and the surface area of ​​the protrusion 34 is further increased.

[0129] The number of protrusions 34 per unit area of ​​the main nickel plating layer 32 may be 2,500 to 7,000 in a plan view. In this case, it is possible to suppress contact between adjacent protrusions 34 and ensure a sufficient surface area of ​​the plating layer 30 .

[0130] It can also be that at a current density of 30A / dm 2 Above 50A / dm 2 Under the following conditions, the steel sheet S provided with the base nickel plating layer 31 is immersed in a Watt bath in which the nickel concentration is set to be 0.15 mol / L or more and less than 0.30 mol / L, thereby forming the main nickel plating layer 32 on the base nickel plating layer 31. In this case, the protrusions 34 in the shape of a rough head are easily formed, so that the surface area of ​​the main nickel plating layer 32 can be further increased.

[0131] Alternatively, the main nickel plating layer 32 may be formed on the base nickel plating layer 31 by immersing the steel sheet S provided with the base nickel plating layer 31 in a Watts bath set at a temperature of 30° C. to 60° C. for 30 seconds to 60 seconds. In this case, the protrusions 34 in the shape of a rough head are further easily formed, so that the surface area of ​​the main nickel plating layer 32 can be further increased.

[0132] The relative speed between the surface S1 of the steel sheet S and the Watt bath may be 0 m / s or more and 1.0 m / s or less in the step of forming the main nickel plating layer 32. In this case, the number of protrusions 34 per unit area can be well controlled.

[0133] In the step of forming the main nickel plating layer 32, a plurality of nickel crystals may be overlapped on at least a portion of the plurality of protrusions 34. In this case, protrusions 34 having a plurality of nickel crystals overlapped are formed with irregularities on their surfaces, and the surface area of ​​the protrusions 34 increases.

[0134] Below, use Fig.15 and Fig.16 A specific example of the process of forming a plating layer on the surface of a steel sheet will be described. Fig.15 This is a schematic diagram illustrating a process of forming a base nickel plating layer on the surface of a steel sheet. Fig.16 It is a schematic diagram illustrating the process of forming a main nickel plating layer on the base nickel plating layer.

[0135] like Fig.15As shown, after the steel plate S wound into a roll by the roller DR2 is pulled out and conveyed along the surface of at least the lower half of the roller DR1, the steel plate S is wound onto the roller DR3. At this time, the lower part of the roller DR1 and the anode 160 are immersed in the electrolyte L1 containing nickel cations. Therefore, the steel plate S in contact with the lower surface of the roller DR1 is immersed in the electrolyte L1. And, during the conveyance of the steel plate S, a predetermined current flows between the roller DR1 and the anode 160. As a result, nickel is precipitated on the surface S1 of the steel plate S immersed in the electrolyte L1 (the surface of the steel plate S located on the opposite side of the surface in contact with the surface of the roller DR1), and the base nickel plating layer 31 having the protrusion 33 is formed on the surface S1 of the steel plate S.

[0136] Then, if Fig.16 As shown, after the steel sheet S wound into a roll shape by the roller DR3 is pulled out and conveyed along the surface of at least the lower half of the roller DR4, the steel sheet S is wound onto the roller DR5. At this time, the lower part of the roller DR4 and the anode 161 are immersed in the Watt bath L2. Therefore, the steel sheet S in contact with the lower surface of the roller DR4 is immersed in the Watt bath L2. And, during the conveyance of the steel sheet S, a predetermined current flows between the roller DR4 and the anode 161. As a result, nickel is precipitated on the base nickel plating layer 31 on the steel sheet S immersed in the Watt bath L2, and a main nickel plating layer 32 including a plurality of protrusions 34 is formed. In addition, the conveyance speed of the steel sheet S is, for example, 1.0 m / s or less, and the Watt bath is set not to flow for reasons other than the rotation of the roller DR4 and the conveyance of the steel sheet S.

[0137] Next, an electrolytic plating method used in at least one of the step of forming the base nickel plating layer and the step of forming the main nickel plating layer described in the above embodiment will be described.

[0138] A first embodiment of the plating device 301 will be described. Fig.17 As shown, the plating device 301 comprises: a plating tank 311; a metal component 317, which serves as an anode; a metal component (substrate) 340, which serves as a cathode; a first clamping member 321 and a second clamping member 325, which clamp the metal component 340; a retaining member 331, which holds the first clamping member 321 and the second clamping member 325 as a whole; a DC power supply 315; and leads 315a, 315b.

[0139] The plating tank 311 stores a plating solution 313. Examples of the plating solution 313 are electrolytes containing nickel cations, such as nickel chloride aqueous solution, nickel sulfate solution, etc. The concentration (mol / L) and temperature (°C) of the plating solution are appropriately set based on the metal to be plated and the plating thickness.

[0140] The metal member 317 forming the anode is, for example, nickel. The metal member 317 is connected to the DC power supply 315 via the lead 15a. The metal member 340 forming the cathode can be, for example, a cold-rolled steel sheet (SPCC, etc.) specified in JIS G3141:2005. The thickness of the metal member 340 can be, for example, 0.1 μm or more and 1000 μm or less.

[0141] like Fig.17 and Fig.18 As shown, the first clamping member 321 is formed by a conductive member 322, and its entire surface is covered (coated) by an insulating material 321a. An example of the material of the conductive member 322 is stainless steel (SUS304), and an example of the material of the insulating material (insulating coating) 321a covering the entire surface of the conductive member 322 is polyester. The first clamping member 321 is provided with an opening portion 321c in the central portion when viewed from the front. The first clamping member 321 is formed with two exposed portions 321b, 321b clamping the opening portion 321c. The exposed portions 321b, 321b are the portions where the insulating material 321a is peeled off and the conductive member 322 is exposed. In the first form, an example in which two exposed portions 321b, 321b are formed is given for explanation, but the exposed portion 321b may be one, or may be three or more.

[0142] The second clamping member 325 is formed of a conductive member 326, the entire surface of which is covered with an insulating material 325a. As with the second clamping member 325, an example of a material of the conductive member 326 is stainless steel (SUS304), and an example of a material of the insulating material 325a covering the entire surface of the conductive member 326 is polyester. Unlike the first clamping member 321, the second clamping member 325 is not provided with an opening 321c in the central portion when viewed from the front. In addition, unlike the first clamping member 321, there is no exposed portion where the insulating material 325a is peeled off and the conductive member 326 is exposed. The first clamping member 321 and the second clamping member 325 are held together by a retaining member 331.

[0143] In the first embodiment, the opening 321c formed in the first clamping member 321 is arranged at the region of the metal member 340 where the plating treatment is desired. In addition, the exposed portions 321b, 321b formed in the first clamping member 321 are arranged at the portion of the metal member 340 where the current is desired to be supplied. The metal member 340 is clamped by the first clamping member 321 and the second clamping member 325 in such a configuration relationship. Next, the metal member 340 clamped in this state is immersed as a cathode in the plating solution stored in the plating tank 311, and current is supplied (voltage is applied) to the first clamping member 321 where the exposed portions 321b, 321b are formed.

[0144] Next, the electrolytic plating method using the above-mentioned plating apparatus 301 will be described in detail. Fig.19 As shown, the electrolytic plating method of the first embodiment includes a first preparation step S301 , a second preparation step S302 , and a plating treatment step S303 .

[0145] In the first preparation step S301, Fig.18 As shown, a first clamping member 321 is prepared in which the entire surface of the conductive member 322 is covered with an insulating material 321a and is provided with an opening 321c; and a second clamping member 325 is prepared in which the entire surface of the conductive member 326 is covered with an insulating material 325a.

[0146] In the second preparation step S302, the insulating material 25a is peeled off from a part of the first clamping member 321 to form an exposed portion 321b exposing the conductive member 322. In the second preparation step S302, a plurality of exposed portions 321b, 321b are formed in the first clamping member 321.

[0147] In the plating process step S303, the first clamping member 321 is arranged so that the opening 321c is arranged in the region of the metal member 340 where the plating process is desired. Next, the first clamping member 321 is arranged so that the exposed portions 321b, 321b are arranged in the portion of the metal member 340 where the current is desired to be supplied. The metal member 340 is clamped by the first clamping member 321 and the second clamping member 325. Next, the metal member 340 clamped by the first clamping member 321 and the second clamping member 325 is immersed as a cathode in the plating solution 313 stored in the plating tank 311, and the current is supplied to the conductive member 322 of the first clamping member 321 having the exposed portions 321b, 321b formed therein. Thus, the current is supplied to the metal member 340 via the exposed portions 321b, 321b.

[0148] Next, the operation and effects of the electrolytic plating method according to the first embodiment will be described.

[0149] According to the electrolytic plating method, before the metal member 340 is clamped by the first clamping member 321 and the second clamping member 325, a power supply portion for supplying power to the metal member 340 can be formed by a simple operation of peeling off a portion of the insulating material from the first clamping member 321. The first clamping member 321 having the exposed portions 321b and 321b can be energized with the metal member 340 in contact via the exposed portions 321b and 321b. Therefore, when the metal member 340 is clamped by the first clamping member 321 and the second clamping member 325, if the first clamping member 321 is arranged in such a manner that the exposed portions 321b and 321b are arranged at the portion of the metal member 340 where the current is desired to be supplied, the metal member 340 can receive the current supply from the exposed portions 321b and 321b. As described above, in order to form the power supply portion, only a portion of the insulating material 321a of the first clamping member 321 needs to be peeled off, so the power supply portion can be arbitrarily changed. As a result, it is possible to easily change the portion where current is supplied to the metal member 340 serving as the cathode during the electrolytic plating process.

[0150] In the second preparation step S302 of the electrolytic plating method, the exposed portions 321b, 321b are formed on the first clamping member 321, so that power can be supplied from around the area where the plating process is desired to be performed to the metal member 340. In addition, during the plating process, the exposed portions 321b, 321b are arranged in the plating solution, so that current can be supplied to the metal member 340 in the plating solution.

[0151] In the second preparation step S302 of the electrolytic plating method, the plurality of exposed portions 321 b and 321 b are formed on the first holding member 321 , so that the power supply locations to the metal member 340 can be dispersed, and the plating process can be performed more uniformly.

[0152] Next, a second embodiment of the plating method will be described. The plating device 301 is the same as that of the first embodiment, and therefore a detailed description thereof will be omitted.

[0153] like Fig. 20 and Fig.21 As shown, the first clamping member 421 is formed of a conductive member 422, the entire surface of which is covered by an insulating material 421a. An example of the material of the conductive member 422 is stainless steel (SUS304), and an example of the material of the insulating material 421a covering the entire surface of the conductive member 422 is polyester. The first clamping member 421 is provided with an opening 421c in the central portion when viewed from the front. The first clamping member 421 is different from the first clamping member 321 of the first form, and is not provided with an exposed portion 321b.

[0154] The second clamping member 425 is formed of a conductive member 426, the entire surface of which is covered by an insulating material 425a. As with the second clamping member 425, an example of a material of the conductive member 426 is stainless steel (SUS304), and an example of a material of the insulating material 425a covering the entire surface of the conductive member 426 is polyester. The second clamping member 425 is formed with an exposed portion 425b at a position overlapping with the opening 421c of the first clamping member 421 when viewed from the front. The exposed portion 425b is a portion where the insulating material 425a is peeled off and the conductive member 426 is exposed. The first clamping member 421 and the second clamping member 425 are held as a whole by the holding member 331.

[0155] In the second embodiment, the opening 421c formed in the first clamping member 421 is arranged at the region of the metal member 340 where the plating treatment is desired. In addition, the exposed portion 425b formed in the second clamping member 425 is arranged at the portion of the metal member 340 where the current is desired to be supplied. That is, the exposed portion 425b is arranged so as to contact the back surface of the region of the metal member 340 where the plating treatment is desired to be performed. The metal member 340 is clamped by the first clamping member 421 and the second clamping member 425 arranged in this way. Next, the metal member 340 clamped in this state is immersed as a cathode in the plating solution stored in the plating tank 311, and the current is supplied (voltage is applied) to the second clamping member 425 where the exposed portion 425b is formed.

[0156] Next, the electrolytic plating method using the above-mentioned plating apparatus 301 will be described in detail. Fig.19 As shown, the electrolytic plating method of the second embodiment also includes a first preparation step S301, a second preparation step S302, and a plating treatment step S303, similarly to the first embodiment.

[0157] In the first preparation step S301, Fig.21 As shown, a first clamping member 421 is prepared, wherein the entire surface of the conductive member 422 is covered by the insulating material 421a and the opening 421c is provided; and a second clamping member 425 is prepared, wherein the entire surface of the conductive member 426 is covered by the insulating material 425a and the exposed portion 425b is formed. In the second preparation step S302, the insulating material 425a is peeled off from a part of the second clamping member 425 to form the exposed portion 425b that exposes the conductive member 426.

[0158] In the plating process step S303, the first clamping member 421 is arranged so that the opening 421c is arranged in the region of the metal member 340 where the plating process is desired. Next, the second clamping member 425 is arranged so that the exposed portion 425b is arranged in the portion of the metal member 340 where the current is desired to be supplied. The metal member 340 is clamped by the first clamping member 421 and the second clamping member 425. Next, the metal member 340 clamped by the first clamping member 421 and the second clamping member 425 is immersed as a cathode in the plating solution 313 stored in the plating tank 311, and the current is supplied to the conductive member 426 of the second clamping member 425 having the exposed portion 425b, and the current is supplied to the metal member 340 via the exposed portion 425b.

[0159] The electrolytic plating method of the second embodiment can also obtain the same effect as the first embodiment. In addition, in the second embodiment, current is supplied from the back side in a manner corresponding to the area where the plating treatment is desired in the metal member 340. Thus, current can be uniformly supplied to the area where the plating treatment is desired, and uniform plating thickness can be achieved.

[0160] One aspect of the present invention is not limited to the first and second aspects. In the first aspect, an example is given in which the exposed portions 321b, 321b are formed in a manner of sandwiching the region to be plated, but one aspect of the present invention is not limited thereto. For example, the exposed portion may be provided in the first clamping member 321 in a manner of surrounding the region to be plated. In addition, in the first aspect, the exposed portion can be formed by a simple operation of peeling off only the portion covered by the insulating material 321a, so that the exposed portion can be easily formed regardless of the shape or size of the exposed portion.

[0161] In the first and second aspects described above, nickel plating is used as an example for explanation, but the first and second aspects can also be applied to copper plating, chrome plating, tin plating, or the like.

[0162] One aspect of the present invention is not limited to the above-mentioned embodiment, and other various modifications are possible. For example, although the base nickel plating layer is not a smooth plating layer in the above-mentioned embodiment, one aspect of the present invention is not limited to this.

[0163] In the above embodiment, if Figure 2 As shown in (a), an example is given in which a plating layer 30 covering one surface S1 of a steel sheet S is formed on the peripheral portion 11c of the current collector 11 and a resin spacer 4 is arranged on the peripheral portion 11c via the plating layer 30, but one aspect of the present invention is not limited thereto. Fig. 22As shown in (a), the resin spacer 4 may be disposed on both surfaces 11a and 11b of the current collector 11. That is, the power storage device 1A may be configured as follows: in the peripheral portion 11c of the current collector 11, one surface S1 of the steel sheet S is bonded to the resin spacer 4 via the plating layer 30, and the other surface S2 of the steel sheet S is covered by the resin spacer 4.

[0164] Moreover, if Fig. 22 As shown in (a), when the resin spacer 4 is arranged on the two surfaces 11a and 11b of the collector 11, deformation and warping of the collector 11, the positive electrode layer 12 or the negative electrode layer 13 caused by the expansion difference or contraction difference between the resin spacer 4 and the collector 11 due to temperature changes (caused by heating and cooling during the manufacturing process of the storage device 1A, reaction heat of the bipolar electrode 3, changes in the external air temperature, etc.), humidity absorption or aging can be reduced.

[0165] In the above embodiment, if Figure 2 As shown in (a), the plating layer 30 is provided on one surface S1 of the steel sheet S, but the plating layer 30 may also be provided on both the one surface S1 and the other surface S2. Fig. 22 As shown in (b), the resin spacer 4 is disposed on both surfaces 11a and 11b of the current collector 11. That is, the power storage device 1B may be configured such that both surfaces S1 and S2 of the steel sheet S are bonded to the resin spacer 4 via the plating layer 30 in the peripheral portion 11c of the current collector 11.

[0166] In the above embodiment, if Figure 2 As shown in (a), the plating layer 30 is provided on one surface S1 of the steel sheet S, but the plating layer 30 may be provided on only the other surface S2 instead of on the one surface S1. In addition, in this case, it may also be, as Fig. 22 As shown in (c), the resin spacer 4 is arranged on the two surfaces 11a and 11b of the collector 11. That is, it is also possible to provide a power storage device 1C having the following structure: in the peripheral portion 11c of the collector 11, one surface S1 of the steel plate S is covered with the resin spacer 4, and the other surface S2 is connected to the resin spacer 4 via the plating layer 30.

[0167] Description of Reference Numerals

[0168] 1, 1A, 1B, 1C…power storage device, 3…bipolar electrode (electrode), 4…resin spacer, 7…spacer, 11…current collector, 11a…one surface, 11b…the other surface, 11c…peripheral portion, 12…positive electrode layer, 13…negative electrode layer, 30…plating layer, 31…base nickel plating layer, 32…main nickel plating layer, 33…convex portion, 34…protrusion, 34a…base end, 34b…top end, 34c…enlarged portion, S…steel plate, S1, S2…surface, 301…plating device, 321…first clamping member, 321a…insulation Material, 321b…exposed portion, 321c…opening portion, 322, 326…conductive component, 325…second clamping component, 325a…insulating material, 331…holding component, 340…metal component (substrate), 421…first clamping component, 421a…insulating material, 421c…opening portion, 422, 426…conductive component, 425…second clamping component, 425a…insulating material, 425b…exposed portion, S301…first preparation step, S302…second preparation step, S303…plating treatment step.

Claims

1. A power storage device, characterized in that: A laminated body having an electrode, wherein the electrode comprises a steel plate and a plating layer provided on a surface of the steel plate, The above-mentioned plating layer has: A base nickel plating layer, which is disposed on the surface of the steel plate; as well as a main nickel plating layer provided on the base nickel plating layer, comprising a plurality of protrusions protruding in a direction intersecting with an extending direction of the surface of the steel sheet, At least a part of the plurality of protrusions is provided with an enlarged portion, the enlarged portion being located closer to the tip end of the protrusion than the base end of the protrusion. The plating layer is formed along the peripheral portion of the electrode, a resin spacer is arranged in the peripheral portion where the plating layer is formed so as to be in contact with the plating layer, a plurality of deposited metals overlap on at least a portion of the plurality of protrusions, and the at least a portion of the protrusions has a rough head shape in which the tip becomes thicker as it goes from the base end side to the tip side due to the overlap of the plurality of deposited metals. A portion of the resin spacer is disposed between two adjacent protrusions of the plurality of protrusions from the distal end to the proximal end, at least one of the two protrusions having the rough head shape, and a cross-sectional shape between the two protrusions is an undercut shape having an anchoring effect.

2. The power storage device according to claim 1, A portion of the resin spacer is interposed between two adjacent protrusions of the plurality of protrusions from the distal end side to the proximal end side and at least one of the protrusions having the enlarged portion.

3. The power storage device according to claim 1 or 2, The average height of the plurality of protrusions is not less than 15 μm and not more than 30 μm.

4. The power storage device according to claim 1 or 2, The above-mentioned precipitated metal is spherical.

5. The power storage device according to claim 1 or 2, The power storage device is a nickel-hydrogen secondary battery.

6. The power storage device according to claim 1 or 2, The precipitated metal is nickel crystals.

7. The power storage device according to claim 1 or 2, The number of the protrusions per unit area of ​​the main nickel plating layer is 2,500 to 7,000 in a plan view.

8. The power storage device according to claim 1 or 2, The electrode is a bipolar electrode having: a current collector including a nickel-plated steel plate; a positive electrode layer disposed on one surface of the current collector; and a negative electrode layer disposed on the other surface of the current collector. The stacked body is formed by stacking a plurality of the bipolar electrodes with separators interposed therebetween. The plating layer is formed on the peripheral portion of the current collector, and a resin spacer is bonded to the peripheral portion. The power storage device includes a cylindrical resin case that surrounds the side surface of the stacked body and holds the stacked body. The above-mentioned power storage device is a bipolar battery.

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