JP2020140774A - Power storage module and manufacturing method thereof - Google Patents

Abstract

To provide a power storage module capable of improving long-term reliability while suppressing manufacturing costs, and a manufacturing method thereof.SOLUTION: A power storage module 12 includes: a stack 30 that includes a bipolar electrode group in which a positive electrode active material is coated on one surface of an electrode plate 34 and a bipolar electrode 32 coated with a negative electrode active material on the other surface is laminated in a first direction, and a metal plate 35 arranged outside the bipolar electrode group in the first direction; and a frame body 50 that holds edge portions 34a and 35c of the electrode plate 34 and the metal plate 35 and covers a side surface 30a of the stack 30 intersecting in the first direction to seal an electrolytic solution between the electrode plates. The metal plate 35 has an inner side surface 35a which faces the bipolar electrode group, and an outer side surface 35b which is a surface opposite to the inner side surface 35a and forms the outermost surface of the stack 30, and at least an outer side surface 35b is rust-proofed.SELECTED DRAWING: Figure 4

Description

The present invention relates to a power storage module and a method for manufacturing the power storage module.

As a conventional power storage module, a bipolar battery including a bipolar electrode having a positive electrode formed on one surface of an electrode plate and a negative electrode formed on the other surface is known (see, for example, Patent Document 1 below). The bipolar battery includes a laminate in which bipolar electrodes and separators are alternately laminated along the stacking direction. A terminal electrode that functions as a take-out electrode is located outside the laminated body in the stacking direction.

Japanese Unexamined Patent Publication No. 2011-204386

In the above-mentioned bipolar battery, the metal plate provided on the outermost layer may rust due to moisture in the air or the like. If a hole is formed in the metal plate due to the progress of the rust, leakage of the electrolytic solution or the like occurs, and the performance of the power storage module is significantly deteriorated.

An object of the present invention is to provide a power storage module and a method for manufacturing a power storage module capable of improving long-term reliability.

The power storage module according to the present invention includes a group of bipolar electrodes in which a positive electrode active material is coated on one surface of an electrode plate and bipolar electrodes coated with a negative electrode active material on the other surface are laminated in the first direction. An electrode plate by holding a laminate having a metal plate arranged on the outside in the first direction of the bipolar electrode group, and covering the side surfaces of the electrode plate and the laminate intersecting in the first direction while holding the peripheral edge of the electrode plate and the metal plate. A frame body for sealing the electrolytic solution between them is provided, and the metal plate forms the outermost surface of the laminate, which is the first surface facing the bipolar electrode group and the surface opposite to the first surface. It has a second surface, and at least the second surface is rust-proofed.

In the power storage module having this configuration, the second surface of the metal plate forming the outermost surface of the laminated body is subjected to rust prevention treatment. As a result, it is possible to suppress the occurrence of leakage of the electrolytic solution or the like with a simple configuration in which the second surface of the metal plate is subjected to a rust preventive treatment. As a result, long-term reliability can be improved.

In the power storage module according to the present invention, the second surface has a frame-shaped region having a predetermined width formed along the outer shape when viewed from the stacking direction, and a rectangular region formed inside the frame-shaped region. The rust preventive treatment may be applied only to the rectangular area. In this configuration, the frame-shaped region, which is the portion where the resin portion is welded, is not rust-proofed. Thereby, the welding between the metal plate and the resin portion can be improved. Further, since the rust preventive treatment is applied to the minimum necessary range in which the moisture in the air and the steel sheet may react with each other, the cost required for the rust preventive treatment can be suppressed.

In the power storage module according to the present invention, a negative electrode active material is formed on the first surface of the metal plate arranged at one end of the bipolar electrode group in the first direction, and the bipolar electrode group is formed in the first direction. A positive electrode active material may be formed on the first surface of the metal plate arranged at the other end. In this configuration, long-term reliability can be improved by a simple configuration in which one surface of the metal plate constituting the negative electrode side terminal electrode and the positive electrode side terminal electrode is subjected to rust prevention treatment.

In the power storage module according to the present invention, between the bipolar electrode group and one of the metal plates, one surface is coated with a negative electrode active material, and the other surface is not coated with an active material. Is arranged, one surface of the negative electrode side terminal electrode faces the bipolar electrode group, and a space may be formed between the metal plate, the negative electrode side terminal electrode, and the frame. In this configuration, an uncoated metal plate not coated with an active material is placed on the outside of the negative electrode side terminal electrode, and one surface of the uncoated metal plate is subjected to a rust preventive treatment. Long-term reliability can be improved while suppressing manufacturing costs. Further, in this configuration, a space formed by the metal plate can be provided between the inside and the outside of the power storage module, so that the progress of alkaline creep can be suppressed.

In the power storage module according to the present invention, the metal plate may be rust-proofed only on the second surface. The power storage module is often eroded from the outside of the power storage module, but with this configuration, such erosion from the outside can be effectively prevented.

In the power storage module according to the present invention, the rust preventive treatment may be a treatment in which a rust preventive agent containing a conductive auxiliary agent is applied. In this configuration, even when a rust inhibitor containing an insulating material such as resin or oil is used, rust can be prevented without impairing the conductivity of the metal plate.

In the power storage module according to the present invention, the metal plate may be plated. As the metal plate, for example, a material such as a nickel-plated steel plate, which is advantageous in terms of cost and reactivity with an electrolytic solution, can be adopted. In this case, if there are plating defects (pinholes) on the surface of the plating layer formed by the plating process, the steel plate may react with moisture in the air at the pinholes, and the metal plate may rust. .. With this configuration, it is possible to prevent the generation of rust generated by such a mechanism, so that it is possible to improve long-term reliability while suppressing the manufacturing cost.

In the power storage module according to the present invention, the plating layer formed by the plating treatment has a plurality of protrusions made of metal protruding in one direction from the surface of the metal plate, and the thickness of the rust preventive film formed by the rust preventive treatment. May be less than or equal to the maximum height of the protrusion. In this configuration, it is possible to prevent the conductivity of the metal plate from being hindered by the rust preventive film formed by the rust preventive treatment.

In the method for manufacturing a power storage module according to the present invention, an electrode plate in which a positive electrode active material is coated on one surface and a negative electrode active material is applied on the other surface, and an active material is applied on one surface. A preparatory step for preparing a metal plate on which the other surface is not coated with an active material and a first resin portion provided over the electrode plate and the edge portion of the metal plate, and a first resin portion on the edge portion of the electrode plate. To form a bipolar electrode unit by welding, and a unit forming step of welding a first resin portion to the edge of a metal plate to form a terminal electrode unit, and the first of a group of bipolar electrodes in which bipolar electrode units are laminated. It is formed by a laminate forming step of arranging a terminal electrode unit on the outside in the direction to form a laminate and surrounding the side surface of the laminate with a second resin portion to integrate the laminate, and a laminate forming step. It includes a rust preventive treatment step of applying a rust preventive treatment to the outer surface of the metal plate arranged on the outermost side of the laminated body.

In the method for manufacturing a power storage module having these configurations, rust prevention treatment can be easily applied to the outer surface of the metal plate forming the outermost surface of the laminated body. In addition, it is possible to suppress the occurrence of leakage of the electrolytic solution or the like with a simple configuration in which the outer surface is subjected to a rust preventive treatment. As a result, long-term reliability can be improved.

In the method for manufacturing a power storage module according to the present invention, a first electrode plate in which a positive electrode active material is coated on one surface and a negative electrode active material is applied on the other surface, and an active material is applied on one surface. The second electrode plate is not coated with the active material on the other surface, the metal plate is not coated with the active material on both sides, the first electrode plate, the second electrode plate, and the edges of the metal plate. A preparatory step for preparing the first resin portion provided over the plate, and welding the first resin portion to the edge portion of the first electrode plate to form a bipolar electrode unit, and first to the edge portion of the second electrode plate. The unit forming step of welding the resin portion to form the terminal electrode unit, and the terminal electrode so that one surface faces the bipolar electrode group on the outside in the first direction of the bipolar electrode group on which the bipolar electrode units are laminated. By arranging the units and forming a laminate in which a metal plate is arranged on the outside of at least one terminal electrode unit and surrounding the side surface of the laminate with a second resin portion, the metal plate, the second electrode plate, and the first The laminated body forming step of integrating the laminated bodies so as to form a space surrounded by the two resin portions, and the outer surface of the metal plate arranged on the outermost side of the laminated body formed by the laminated body forming step are prevented. Includes a rust preventive treatment step of applying rust treatment.

In the method for manufacturing a power storage module having these configurations, rust prevention treatment can be easily applied to the outer surface of the metal plate forming the outermost surface of the laminated body. In addition, it is possible to suppress the occurrence of leakage of the electrolytic solution or the like with a simple configuration in which the outer surface is subjected to a rust preventive treatment. As a result, long-term reliability can be improved. Further, in this configuration, a space formed by the metal plate can be provided between the inside and the outside of the power storage module, so that the progress of alkaline creep can be suppressed.

In the method for manufacturing a power storage module according to the present invention, the metal plate may be plated. In the method of manufacturing a power storage module having this configuration, even if a pinhole or the like exists on the surface of the outermost current collector, it is possible to prevent the moisture in the air from reacting with the steel plate at the pinhole. It is possible to manufacture a power storage module that can be used. As a result, long-term reliability can be improved while suppressing the manufacturing cost.

According to the present invention, long-term reliability can be improved while suppressing the manufacturing cost.

It is a schematic sectional drawing which shows the power storage device which concerns on one Embodiment. It is schematic cross-sectional view which shows the power storage module included in the power storage device shown in FIG. It is a perspective view which shows the power storage module shown in FIG. It is sectional drawing of the plating layer near the central part of the metal plate shown in FIG. It is a top view which looked at the electrode plate included in the negative electrode side end electrode shown in FIG. 2 from the outside of a laminated body. It is a flowchart which shows the manufacturing method of the power storage module which concerns on one Embodiment. It is the schematic sectional drawing which shows a part of the power storage module which concerns on a modification.

Hereinafter, one embodiment will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and duplicate description is omitted. 1 to 3 and 6 show an XYZ Cartesian coordinate system.

The configuration of the power storage device 10 including the power storage module 12 according to the embodiment will be described. The power storage device 10 is used as a battery for various vehicles such as forklifts, hybrid vehicles, and electric vehicles. The power storage module 12 is, for example, a bipolar battery. The power storage module 12 is, for example, a secondary battery such as a nickel hydrogen secondary battery or a lithium ion secondary battery, but may be an electric double layer capacitor. In the following description, a nickel hydrogen secondary battery will be illustrated.

As shown in FIG. 1, the power storage device 10 includes a plurality of power storage modules 12, a conductive plate 14, and a restraint member 16.

The plurality of power storage modules 12 are laminated via a conductive plate 14 such as a metal plate. The power storage module 12 and the conductive plate 14 have, for example, a rectangular shape when viewed from the stacking direction D1 (Z direction: first direction). Details of each power storage module 12 will be described later. The conductive plate 14 is also arranged on the outside of the power storage module 12 located on the outside in the stacking direction D1 of the power storage module 12. The conductive plate 14 is electrically connected to the adjacent power storage modules 12. As a result, the plurality of power storage modules 12 are electrically connected in series in the stacking direction D1.

In the stacking direction D1, the terminal member 24 is connected to the conductive plate 14 located at one end, and the terminal member 26 is connected to the conductive plate 14 located at the other end. The terminal member 24 may be integrated with the conductive plate 14 to be connected. The terminal member 26 may be integrated with the conductive plate 14 to be connected. The terminal member 24 and the terminal member 26 extend in a direction (X direction) intersecting the stacking direction D1. The terminal member 24 and the terminal member 26 can charge and discharge the power storage device 10.

In the power storage device 1, the power storage module 2 may be arranged at one end and the other end in the stacking direction. That is, the outermost layer (the outermost layer of the stack) of the laminate of the power storage module 2 and the conductive plate 3 in the power storage device 1 may be the power storage module 2. In this case, the positive electrode terminal 4 and the negative electrode terminal 5 are provided for the power storage module 2 in the outermost layer of the stack.

The conductive plate 14 can also function as a heat radiating plate for releasing the heat generated in the power storage module 12. By allowing a refrigerant such as air to pass through the plurality of voids 14a provided inside the conductive plate 14, the heat from the power storage module 12 can be efficiently released to the outside. Each void 14a extends in a direction (Y direction) intersecting the stacking direction D1, for example. The conductive plate 14 is smaller than the power storage module 12 when viewed from the stacking direction D1, but may be the same as or larger than the power storage module 12.

The restraint member 16 includes a pair of restraint plates 16A and 16B and connecting members (bolts 18 and nuts 20) that connect the restraint plates 16A and 16B to each other. An insulating film 22 such as a resin film is arranged between the restraint plates 16A and 16B and the conductive plate 14. Each of the restraint plates 16A and 16B is made of a metal such as iron. Seen from the stacking direction D1, each of the restraint plates 16A and 16B and the insulating film 22 has, for example, a rectangular shape. The insulating film 22 is larger than the conductive plate 14, and the restraint plates 16A and 16B are larger than the power storage module 12.

When viewed from the stacking direction D1, an insertion hole H1 through which the shaft portion of the bolt 18 is inserted is provided at a position outside the power storage module 12 at the edge portion of the restraint plate 16A. Similarly, when viewed from the stacking direction D1, an insertion hole H2 through which the shaft portion of the bolt 18 is inserted is provided at a position outside the power storage module 12 at the edge portion of the restraint plate 16B. When the restraint plates 16A and 16B have a rectangular shape when viewed from the stacking direction D1, the insertion holes H1 and the insertion holes H2 are located at the corners of the restraint plates 16A and 16B.

One restraint plate 16A is abutted against the conductive plate 14 connected to the terminal member 26 via the insulating film 22, and the other restraint plate 16B has the insulating film 22 attached to the conductive plate 14 connected to the terminal member 24. It is struck through. For example, the bolt 18 is passed through the insertion hole H1 from one restraint plate 16A side toward the other restraint plate 16B side, and a nut 20 is screwed into the tip of the bolt 18 protruding from the other restraint plate 16B. There is. As a result, the insulating film 22, the conductive plate 14, and the power storage module 12 are sandwiched and unitized, and a restraining load is applied to the stacking direction D1. When the outermost layer of the stack is the power storage module 2, the insulating film 22 is interposed between each restraint plate 7 and the power storage module 2.

As shown in FIG. 2, the power storage module 12 includes a plurality of bipolar electrodes 32 (bipolar electrode group), a negative electrode side terminal electrode 39 arranged outside the bipolar electrode group in the stacking direction D1 of the bipolar electrode 32, and a positive electrode side. A laminated body 30 having a terminal electrode 37 is provided. The laminated body 30 has, for example, a rectangular shape when viewed from the stacking direction D1. A separator 47 is arranged between the adjacent bipolar electrodes 32. The bipolar electrode 32 includes an electrode plate 34, a positive electrode 36 provided on one surface of the electrode plate 34, and a negative electrode 38 provided on the other surface of the electrode plate 34. In the laminate 30, the positive electrode 36 of one bipolar electrode 32 faces the negative electrode 38 of one of the bipolar electrodes 32 adjacent to the stacking direction D1 with the separator 47 interposed therebetween, and the negative electrode 38 of one bipolar electrode 32 is the separator 47. Is opposed to the positive electrode 36 of the other bipolar electrode 32 adjacent to each other in the stacking direction D1.

The negative electrode side terminal electrode 39 is arranged at one end of the bipolar electrode group in the stacking direction D1. The negative electrode side terminal electrode 39 is a metal plate in which the negative electrode (negative electrode active material) 38 is arranged on the inner side surface (first surface) 35a and the active material is not arranged on the outer side surface (second surface) 35b in the stacking direction D1. Has 35. The negative electrode 38 of the negative electrode side terminal electrode 39 faces the positive electrode 36 of the uppermost bipolar electrode 32 via the separator 47.

The positive electrode side terminal electrode 37 is a metal plate in which the positive electrode (positive electrode active material) 36 is arranged on the inner side surface (first surface) 35a and the active material is not arranged on the outer side surface (second surface) 35b in the stacking direction D1. Has 35. The positive electrode 36 of the positive electrode side terminal electrode 37 faces the negative electrode 38 of the lowermost bipolar electrode 32 via the separator 47. The metal plate 35 of the negative electrode side terminal electrode 39 and the metal plate 35 of the positive electrode side terminal electrode 37 are connected to adjacent conductive plates 14 (see FIG. 1), respectively.

The power storage module 12 includes a frame body 50 that holds the edge portion 34a of the electrode plate 34 on the side surface 30a of the laminated body 30 extending in the stacking direction D1. The side surface 30a of the laminated body 30 is composed of an end surface connecting one surface and the other surface of the electrode plate 34. The frame body 50 is provided around the laminated body 30 when viewed from the stacking direction D1. That is, the frame body 50 is configured to hold the edge portion 34a of the electrode plate 34 and the edge portion 35c of the metal plate 35 and to surround the side surface 30a of the laminated body 30. The frame body 50 is provided on the edge portion 34a of each electrode plate 34 and the edge portion 35c of the metal plate 35, and has an end portion 34b of the electrode plate 34 and an overhanging portion 52b protruding from the edge portion 35c of the metal plate 35, respectively. A plurality of first resin portions 52 and a second resin portion 54 provided around the first resin portion 52 when viewed from the stacking direction D1 may be provided.

The first resin portion 52 constituting the inner wall of the frame body 50 is provided from one surface of the electrode plate 34 of each bipolar electrode 32 (here, the surface on which the positive electrode 36 is formed) to the end surface of the electrode plate 34 at the edge portion 34a. Has been done. Seen from the stacking direction D1, each first resin portion 52 is provided over the entire circumference of the edge portion 34a of the electrode plate 34 of each bipolar electrode 32. The adjacent first resin portions 52 are in contact with each other on a surface extending to the outside of the other surface (here, the surface on which the negative electrode 38 is formed) of the electrode plate 34 of each bipolar electrode 32. As a result, the edge portion 34a of the electrode plate 34 of each bipolar electrode 32 is buried and held in the first resin portion 52.

Similar to the edge portion 34a of the electrode plate 34 of each bipolar electrode 32, the edge portion 35c of the metal plate 35 arranged outside the bipolar electrode group is also held in a state of being buried in the first resin portion 52. Specifically, regarding the positive electrode side terminal electrode 37, the first resin portion 52 is also provided on the outer surface (the surface connected to the conductive plate 14) of the positive electrode side terminal electrode 37. That is, the edge portion 35c of the metal plate 35 of the positive electrode side terminal electrode 37 is the first resin portion 52 provided on the outer surface of the positive electrode side terminal electrode 37 (the first resin portion 52 provided at the bottom in FIG. 2). ) And the first resin portion 52 provided on the inner side surface 35a of the metal plate 35 of the positive electrode side terminal electrode 37, and are held in a state of being buried.

Inside the frame 50 of the power storage module 12, there are a plurality of internal spaces V surrounded by adjacent electrode plates 34, 34 and the first resin portion 52, and the electrode plate 34, the metal plate 35, and the first resin portion 52. Two interior spaces V surrounded by are formed. The internal space V is filled with the electrolytic solution E. As shown in FIG. 3, each internal space V is connected to a pressure regulating valve (not shown) via an opening 50e formed in a frame body 50 that seals (seals) the internal space V. ing.

The frame body 50 (first resin portion 52 and second resin portion 54) is formed in a rectangular tubular shape by, for example, injection molding using an insulating resin. Examples of the resin material constituting the frame 50 include polypropylene (PP), polyphenylene sulfide (PPS), modified polyphenylene ether (modified PPE), and the like.

A plurality of openings are formed on one side surface 50s (here, one side surface 50s facing the longitudinal direction (Y direction) of the frame body 50) forming one side of the frame body 50 when viewed from the stacking direction D1 (see FIG. 1). A portion 50e is provided. Each of the openings 50e communicates with each of the internal spaces V. Each opening 50e (for example, 24 pieces) functions as a liquid injection port for injecting the electrolytic solution E into each internal space V (for example, 24 pieces), and after the electrolytic solution E is injected, a pressure adjusting valve. Functions as a connection port for.

As shown in FIGS. 2 and 3, the second resin portion 54 constituting the outer wall of the frame body 50 is a tubular portion extending in the stacking direction D1 in the axial direction. The second resin portion 54 extends over the entire length of the laminated body 30 in the stacking direction D1. The second resin portion 54 covers the outer surface of the first resin portion 52 extending in the stacking direction D1. The second resin portion 54 is formed by, for example, injection molding or the like. The second resin portion 54 is formed by installing a mold on the peripheral edge of the first resin portion 52 and pouring the resin material of the second resin portion 54 having fluidity into the mold. As a result, the frame body 50 having the first resin portion 52 and the second resin portion 54 is formed.

The electrode plate 34 is, for example, a nickel-plated steel plate. The edge portion 34a of the electrode plate 34 is an uncoated region in which the positive electrode active material and the negative electrode active material are not coated, and the uncoated region is buried in the first resin portion 52 constituting the inner wall of the frame body 50. It is an area that is held. Examples of the positive electrode active material constituting the positive electrode 36 include nickel hydroxide. Examples of the negative electrode active material constituting the negative electrode 38 include a hydrogen storage alloy. The formation region of the negative electrode 38 on the other surface of the electrode plate 34 is slightly larger than the formation region of the positive electrode 36 on one surface of the electrode plate 34.

The separator 47 is formed in a sheet shape, for example. Examples of the material for forming the separator 47 include a porous film made of a polyolefin resin such as polyethylene (PE) and polypropylene (PP), a woven fabric made of polypropylene or the like, or a non-woven fabric. Further, the separator 47 may be reinforced with a vinylidene fluoride resin compound or the like.

Here, the metal plate 35 included in the negative electrode side terminal electrode 39 will be described in detail. As shown in FIG. 2, the metal plate 35 has an outer surface 35b and an inner surface 35a. The inner side surface 35a of the metal plate 35 is coated with a negative electrode active material. Further, on the inner side surface 35a of the metal plate 35, the edge portion 35c is an uncoated region where the negative electrode active material is not coated, and the uncoated region constitutes the inner wall of the frame body 50. It is an area that is buried and held in. Examples of the negative electrode active material constituting the negative electrode 38 include a hydrogen storage alloy.

The metal plate 35 is a steel plate (nickel-plated steel plate) S whose surface is nickel-plated. Examples of the steel sheet include cold-rolled steel sheets (SPCC and the like) specified in JIS G 3141: 2005. The thickness of the metal plate 35 may be, for example, 0.1 μm or more and 1000 μm or less. As shown in FIG. 4, a roughened plating layer 40 covering one surface S11 of the steel plate S is formed on the outer surface 35b of the metal plate 35. The roughened plating layer 40 is formed on the surface S11 of the steel plate S by subjecting the steel plate S constituting the metal plate 35 to an electrolytic nickel plating treatment (electroplating treatment). That is, the roughened plating layer 40 corresponds to the nickel plating layer formed by the electrolytic plating treatment.

As an example, the roughened plating layer 40 has a first nickel plating layer 41 provided on one surface S11 of the steel plate S and a second nickel plating layer 42 provided on the first nickel plating layer 41. The first nickel plating layer 41 and the second nickel plating layer 42 are formed by performing electrolytic plating under different conditions.

The first nickel plating layer 41 is an electrolytic plating layer provided on one surface S11 of the steel sheet S along the in-plane direction D2 intersecting the stacking direction D1. The in-plane direction D2 corresponds to the direction along the XY plane or the extending direction of one surface S11. Therefore, the in-plane direction D2 does not necessarily have to be orthogonal to the stacking direction D1. The first nickel-plated layer 41 covers the entire surface S11 on one side.

The first nickel-plated layer 41 has a plurality of convex portions 43 protruding along the stacking direction D1. Therefore, the surface shape of the first nickel plating layer 41 is rougher than the surface shape of one surface S11 of the steel plate S. The plurality of convex portions 43 are irregularly provided along the in-plane direction D2. When the thickness of the first nickel plating layer 41 is about 1 μm or more, the average height of the convex portion 43 is, for example, 0.4 μm or more, which is about half or less of the thickness of the first nickel plating layer 41. Is. In this case, the shape of the second nickel plating layer 42 can be improved. The average height of the convex portion 43 is measured using, for example, a microscope using a laser confocal optical system.

The second nickel plating layer 42 is an electrolytic plating layer provided with the first nickel plating layer 41 as a surface to be deposited, and has a surface roughness larger than that of the first nickel plating layer 41. The second nickel plating layer 42 does not necessarily have to be formed so as to cover the entire surface of the first nickel plating layer 41. Each of the plurality of protrusions 44 is formed so as to reach the tip 44b along the stacking direction D1 with the portion in contact with the corresponding convex portion 43 as the base end 44a.

At least a part of the plurality of protrusions 44 contains a precipitated metal (additive) such as a nickel crystal having a substantially spherical shape. By superimposing such precipitated metals on each other, an enlarged portion 44c is formed in which the length dimension of the protrusion 44 in the in-plane direction D2 is larger than the length dimension of the base end 44a in the in-plane direction D2. That is, at least a part of the protrusions 44 has a thickened shape that becomes thicker from the base end 44a side toward the tip end 44b side. The position of the enlarged portion 44c in the protrusion 44 does not necessarily have to be the tip 44b, but is located at least on the tip 44b side of the base end 44a. The position of the enlarged portion 44c on the protrusion 44 may be different for each protrusion 44 depending on the overlapping mode of the deposited metal.

As shown in FIG. 5, the outer surface 35b of the metal plate 35 has a frame-shaped region 135 having a predetermined width formed along the outer shape when viewed from the Z direction (stacking direction D1) and the inside of the frame-shaped region. It has a rectangular region 235 formed in the.

The frame-shaped region 135 of the metal plate 35 is a portion welded to the first resin portion 52. In the frame-shaped region 135 of the metal plate 35, the first resin portion 52 is provided so as to be in contact with the roughened plating layer 40. Although not shown, a part of the first resin portion 52 is interposed between the two adjacent protrusions 44 in the plurality of protrusions 44. For example, a part of the resin is interposed between the protrusions 44 before the resin constituting the first resin portion 52 is cured. Then, by curing the entire resin, a part of the first resin portion 52 is interposed between the protrusions 44. As a result, the two adjacent protrusions 44 restrict the movement of a part of the intervening first resin portion 52 in the direction away from the base end 44a. That is, the roughened plating layer 40 is provided in order to secure the bond strength and liquidtightness between the steel plate S and the first resin portion 52 and to increase the surface area of the metal plate 35.

The rectangular region 235 of the metal plate 35 is a portion in which the conductive plate 14 is brought into contact with the power storage device 10 (see FIG. 1) in order to electrically connect to the adjacent power storage modules 12. The rectangular region 235 of the metal plate 35 is rust-proofed, and the frame-shaped region 135 is not rust-proofed. That is, the metal plate 35 of the negative electrode side terminal electrode 39 is rust-proofed only on the rectangular region 235 of the outer surface 35b. The rectangular region 235 may be rust-proofed by applying a rust-preventive oil, or may be rust-proofed by applying a water-soluble rust inhibitor. As shown in FIG. 4, the thickness T of the rust preventive film 45 formed by the rust preventive treatment may be equal to or less than the maximum height H of the protrusions 44 formed as the roughened plating layer 40 on the metal plate 35.

Here, examples of the rust preventive oil include VERZONE OIL-U manufactured by Daiwa Kasei Co., Ltd. and Killeslite P300 manufactured by Kirest Co., Ltd. Examples of the water-soluble rust preventive agent include HYP-W25 manufactured by NMC Co., Ltd. and W-7PK manufactured by Sugimura Chemical Industrial Co., Ltd. The rust preventive treatment may be performed by applying a rust preventive agent containing a conductive auxiliary agent. Examples of the conductive auxiliary agent are not limited as long as they are materials having electronic conductivity such as carbon, metal, conductive oxide, and conductive resin. Carbon and metal are preferable in that higher conductivity can be expected.

Similarly, the metal plate 35 included in the positive electrode side terminal electrode 37 will be described in detail. The metal plate 35 of the positive electrode side terminal electrode 37 is also a nickel-plated steel plate on which the roughened plating layer 40 is formed, like the metal plate 35 of the negative electrode side terminal electrode 39, for example. Since the roughened plating layer 40 has the same configuration as described above, detailed description thereof will be omitted here. The inner side surface 35a of the metal plate 35 is coated with a positive electrode active material. Further, on the inner side surface 35a of the metal plate 35, the edge portion 35c is an uncoated region where the positive electrode active material is not coated, and the uncoated region constitutes the inner wall of the frame body 50. It is an area that is buried and held in. Examples of the positive electrode active material constituting the positive electrode 36 include nickel hydroxide.

The metal plate 35 has an outer surface 35b and an inner surface 35a. The outer side surface 35b has a frame-shaped region 135 having a predetermined width formed along the outer shape when viewed from the Z direction (stacking direction D1), and a rectangular region 235 formed inside the frame-shaped region. ing. The rectangular region 235 is rust-proofed, and the frame-shaped region 135 is not rust-proofed. That is, the metal plate 35 of the positive electrode side terminal electrode 37 is rust-proofed only on the rectangular region 235 of the outer surface 35b. The rectangular region 235 may be rust-proofed by applying the above-mentioned rust preventive oil, or may be rust-proofed by applying the above-mentioned water-soluble rust preventive.

Next, a method of manufacturing the power storage module 12 including a method of preventing rust on the metal plates 35 and 35 will be described.

Next, a method of manufacturing the power storage module 12 according to the present embodiment will be described. As shown in FIG. 6, the method for manufacturing the power storage module 12 of the present embodiment includes a preparation step S1, a unit forming step S2, a laminate forming step S3, and a rust prevention treatment step S4.

In this manufacturing method, first, the bipolar electrode 32, the first resin portion 52, the metal plate 35 of the negative electrode side terminal electrode 39, and the metal plate 35 of the positive electrode side terminal electrode 37 are prepared (preparation step S1). Subsequently, the first resin portion 52 is welded to the edge portion 34a on one surface of the electrode plate 34 of the bipolar electrode 32 to form the bipolar electrode unit, and the frame on the outer surface 35b of the metal plate 35 of the negative electrode side terminal electrode 39. The first resin portion 52 is welded to the shaped region 135 to form the negative electrode side terminal electrode unit, and the first resin portion 52 is welded to the frame-shaped region 135 on the outer surface 35b of the metal plate 35 of the positive electrode side terminal electrode 37. The positive electrode side terminal electrode unit is formed (unit forming step S2).

Subsequently, the bipolar electrode units are laminated along the stacking direction D1 to form the bipolar electrode unit group. Next, the negative electrode side terminal electrode unit is arranged so that the negative electrode 38 of the negative electrode side terminal electrode 39 faces the bipolar electrode unit group at one end in the stacking direction D1 of the bipolar electrode unit group. Next, at the other end of the stacking direction D1 of the bipolar electrode unit group, the positive electrode side terminal electrode unit is arranged so that the positive electrode 36 of the positive electrode side terminal electrode 37 faces the bipolar electrode unit group. Next, a mold is installed on the peripheral edge of the laminated body 30, and the resin material of the second resin portion 54 having fluidity is poured into the mold. As a result, the frame body 50 having the first resin portion 52 and the second resin portion 54 is formed (laminate body forming step S3).

Subsequently, rust preventive oil is applied to the outer surface 35b of the metal plate 35 of the negative electrode side terminal electrode 39 and the outer surface 35b of the metal plate 35 of the positive electrode side terminal electrode 37. At this time, the rust preventive oil is applied so that the thickness T of the rust preventive film 45 is equal to or less than the maximum height H of the protrusions 44 (see FIG. 4). The rust preventive oil is applied to the exposed portion of the metal plate 35 in the laminate 30 formed in the laminate forming step S3. That is, the rust preventive treatment of the present embodiment is carried out on the rectangular region 235 (see FIG. 5) in the metal plate 35 of the negative electrode side terminal electrode 39 and the positive electrode side terminal electrode 37. For the rust preventive treatment on the metal plate 35, a water-soluble rust preventive agent may be applied instead of applying the rust preventive oil. By going through the steps S1 to S4, the power storage module 12 as shown in FIG. 2 is formed.

Next, the action and effect of the power storage module 12 of the above embodiment will be described. In the method of manufacturing the power storage module 12 and the power storage module 12 of the above embodiment, the outer surface 35b of the metal plate 35 forming the outermost surface of the laminated body 30 is subjected to rust prevention treatment. Therefore, even if a pinhole or the like is present on the outer surface 35b of the metal plate 35, it is possible to prevent the steel plate from reacting with the moisture or the like in the air at the pinhole. As a result, it is possible to suppress the occurrence of leakage of the electrolytic solution or the like with a simple configuration in which the outer surface 35b of the metal plate 35 is subjected to a rust preventive treatment. As a result, long-term reliability can be improved while suppressing the manufacturing cost.

In the power storage module 12 of the above embodiment, the rust preventive treatment is applied only to the rectangular region 235 of the metal plate 35. In other words, the frame-shaped region 135, which is the portion where the first resin portion 52 is welded, is not rust-proofed. Thereby, the welding between the metal plate 35 and the first resin portion 52 can be improved. Further, since the rust preventive treatment is applied to the minimum necessary range in which the moisture in the air and the steel sheet may react with each other, the cost required for the rust preventive treatment can be suppressed.

In the power storage module 12 of the above embodiment, the manufacturing cost is as simple as applying rust preventive treatment to the outer surfaces 35b and 35b of the metal plates 35 and 35 constituting the negative electrode side terminal electrode 39 and the positive electrode side terminal electrode 37, respectively. It is possible to improve long-term reliability while suppressing the problem.

Although one embodiment has been described in detail above, the present invention is not limited to the above embodiment.

In the above embodiment, an example in which the outer surfaces 35b and 35b of the metal plates 35 and 35 constituting the negative electrode side terminal electrode 39 and the positive electrode side terminal electrode 37 are subjected to rust prevention treatment has been described, but the present invention is limited to this. Not done. For example, as shown in FIG. 7, a bipolar electrode group composed of a plurality of bipolar electrodes 32 including an electrode plate (first electrode plate) 34, and metal plates (second electrodes) arranged at both outer ends of the bipolar electrode group. An uncoated metal plate 335 having no active material coated on both sides is arranged on the outside of the negative electrode side terminal electrode 39 and the positive electrode side terminal electrode 37 including the plate) 35 and the negative electrode side terminal electrode 39. It is also possible to apply to such a power storage module 12. The uncoated metal plate 335 has an inner side surface (first surface) 335a facing the bipolar electrode group (negative electrode side terminal electrode 39) and a surface opposite to the inner side surface 335a, which is the outermost surface of the laminate 30. It has an outer surface (second surface) 335b forming the above. The uncoated metal plate 335 is a nickel-plated steel sheet having the above-mentioned roughened plating layer 40 formed on at least the outer surface 335b.

The uncoated metal plate 335 is rust-proofed only on the outer surface 335b. More specifically, the outer surface 335b has a frame-shaped region 435 having a predetermined width formed along the outer shape when viewed from the Z direction (stacking direction D1) and a rectangular region 535 formed inside the frame-shaped region. And have. The rectangular region 535 is rust-proofed, and the frame-shaped region 435 is not rust-proofed. That is, the uncoated metal plate 335 is rust-proofed only on the rectangular region 535 of the outer surface 35b. The rectangular region 535 may be rust-proofed by applying a rust-preventive oil, or may be rust-proofed by applying a water-soluble rust inhibitor. In this case as well, the thickness T of the rust preventive film 45 formed by the rust preventive treatment may be equal to or less than the maximum height H of the protrusions 44 formed on the metal plate 35.

In the power storage module 312 according to the modified example, the outer surface 35b of the metal plate 35 of the negative electrode side terminal electrode 39 is not subjected to rust prevention treatment. Instead, only the outer surface 335b of the uncoated metal plate 335 is rust-proofed. Since the other configurations are the same as those in the above embodiment, detailed description here will be omitted.

In the power storage module 312 according to the modified example, an uncoated metal plate 335 is arranged on the outside of the negative electrode side terminal electrode 39, and the outer surface 335b of the uncoated metal plate 335 is subjected to a rust preventive treatment. As a result, long-term reliability can be improved while suppressing manufacturing costs. Further, in the power storage module 312 according to the modified example, a space VA surrounded by the metal plate 335, the negative electrode side terminal electrode 39, and the frame body 50 is formed. That is, in the power storage module 312 according to the modified example, the space VA formed by the metal plate 335 can be provided between the internal space V and the outside, so that the progress of alkaline creep can be suppressed.

In the above-described embodiment and modification, a nickel-plated steel sheet in which a part of the rectangular region 235 (535) on the outer surface 35b (335b) of the metal plate 35 (335) is rust-proofed has been described as an example. A nickel-plated steel sheet in which all regions of the outer side surface 35b (335b) are rust-proofed may be used.

In the above-described embodiment and modification, an example in which a nickel-plated steel sheet on which the roughened plating layer 40 is formed is used as the metal plate 35 (335) has been described, but a nickel-plated steel sheet on which a normal smooth plating layer is formed is used. It may be used, or a metal plate such as nickel foil which has not been plated may be used.

Although the plating layer of the electrode plate 34 has not been described in detail in the above embodiment and the modified example, the same configuration as that of the roughened plating layer 40 formed on the metal plate 35 may be used.

In the above-described embodiment and modification, the frame body 50 is formed on the peripheral edge of the electrode plate 34 by injection molding. However, the frame is formed by welding the first resin portion 52 to the peripheral edge of the electrode plate 34. The body 50 may be formed.

10 ... power storage device, 12 ... power storage module, 30 ... laminate, 32 ... bipolar electrode, 34 ... electrode plate, 35 ... metal plate, 35a, 335a ... inner surface (first surface), 35b, 335b ... outer surface (third surface) Two sides), 35c ... edge, 36 ... positive electrode, 37 ... positive electrode side terminal electrode, 38 ... negative electrode, 39 ... negative electrode side terminal electrode, 40 ... roughened plating layer (plating layer), 44 ... protrusion, 45 ... rust prevention Film, 50 ... Frame, 52 ... First resin part, 54 ... Second resin part, 135,435 ... Frame-shaped area, 235,535 ... Rectangular area, 312 ... Power storage module, 335 ... Metal plate, S1 ... Preparation step , S2 ... Unit forming step, S3 ... Laminated body forming step, S4 ... Rust prevention treatment step.

Claims (11)

A group of bipolar electrodes in which a positive electrode active material is coated on one surface of an electrode plate and bipolar electrodes coated with a negative electrode active material on the other surface are laminated in the first direction, and the first of the bipolar electrode groups. A laminate having a metal plate arranged on the outside in the direction, and
A frame body that holds the peripheral edges of the electrode plate and the metal plate and seals the electrolytic solution between the electrode plates by covering the side surfaces of the laminated body that intersects in the first direction is provided.
The metal plate has a first surface facing the bipolar electrode group and a second surface which is a surface opposite to the first surface and forms the outermost surface of the laminate. A power storage module in which at least the second surface is rust-proofed. The second surface has a frame-shaped region having a predetermined width formed along the outer shape when viewed from the stacking direction, and a rectangular region formed inside the frame-shaped region.
The power storage module according to claim 1, wherein the rust preventive treatment is applied only to the rectangular region. A negative electrode active material is formed on the first surface of the metal plate arranged at one end of the bipolar electrode group in the first direction.
The power storage module according to claim 1 or 2, wherein a positive electrode active material is formed on the first surface of the metal plate arranged at the other end of the bipolar electrode group in the first direction. Between the bipolar electrode group and one of the metal plates, a negative electrode side terminal electrode is arranged such that a negative electrode active material is coated on one surface and the negative electrode side terminal electrode is not coated on the other surface.
One surface of the negative electrode side terminal electrode faces the bipolar electrode group.
The power storage module according to claim 1 or 2, wherein a space is formed between the metal plate, the negative electrode side terminal electrode, and the frame body. The power storage module according to any one of claims 1 to 4, wherein the metal plate is subjected to the rust preventive treatment only on the second surface. The power storage module according to any one of claims 1 to 5, wherein the rust preventive treatment is a treatment in which a rust preventive agent containing a conductive auxiliary agent is applied. The power storage module according to any one of claims 1 to 5, wherein the metal plate is plated. The plating layer formed by the plating treatment has a plurality of protrusions made of metal protruding in one direction from the surface of the metal plate.
The power storage module according to claim 7, wherein the thickness of the rust preventive film formed by the rust preventive treatment is equal to or less than the maximum height of the protrusions. An electrode plate with a positive electrode active material coated on one surface and a negative electrode active material coated on the other surface, and an active material coated on one surface and an active material on the other surface. A preparatory step for preparing a metal plate that is not provided, and a first resin portion provided over the electrode plate and the edge portion of the metal plate.
A unit forming step of welding the first resin portion to the edge portion of the electrode plate to form a bipolar electrode unit and welding the first resin portion to the edge portion of the metal plate to form a terminal electrode unit. ,
The terminal electrode unit is arranged on the outside in the first direction of the bipolar electrode group on which the bipolar electrode units are laminated to form a laminate, and the side surface of the laminate is surrounded by a second resin portion to form the laminate. Laminated body forming process to be integrated and
A method for manufacturing a power storage module, which comprises a rust preventive treatment step of applying a rust preventive treatment to an outer surface of the metal plate arranged on the outermost side of the laminated body formed by the laminate forming step. A first electrode plate with a positive electrode active material coated on one surface and a negative electrode active material coated on the other surface, and an active material coated on one surface and an active material on the other surface. A second electrode plate that is not coated, a metal plate that is not coated with an active material on both sides, a first electrode plate, a second electrode plate, and a first resin portion that is provided over the edges of the metal plate. The preparation process to prepare, and
The first resin portion is welded to the edge portion of the first electrode plate to form a bipolar electrode unit, and the first resin portion is welded to the edge portion of the second electrode plate to form a terminal electrode unit. , Unit formation process,
The terminal electrode unit is arranged on the outside in the first direction of the bipolar electrode group on which the bipolar electrode units are laminated so that one surface faces the bipolar electrode group, and the outer side of at least one terminal electrode unit. By forming a laminated body in which the metal plate is arranged and surrounding the side surface of the laminated body with a second resin portion, a space surrounded by the metal plate, the second electrode plate, and the second resin portion is formed. A laminate forming step of integrating the laminates so as to be performed,
A method for manufacturing a power storage module, which comprises a rust preventive treatment step of applying a rust preventive treatment to an outer surface of the metal plate arranged on the outermost side of the laminated body formed by the laminate forming step. The method for manufacturing a power storage module according to claim 9 or 10, wherein the metal plate is plated.

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