WO2017179492A1

WO2017179492A1 - Metal sheet for battery container, and method of manufacturing metal sheet for battery container

Info

Publication number: WO2017179492A1
Application number: PCT/JP2017/014429
Authority: WO
Inventors: 慎一郎堀江; 吉村　国浩; 興吉岡; 秀彦小林
Original assignee: 東洋鋼鈑株式会社
Priority date: 2016-04-13
Filing date: 2017-04-07
Publication date: 2017-10-19
Also published as: CN108701782B; JP6913440B2; JP2017191703A; KR102323071B1; CN108701782A; KR20180134327A

Abstract

[Problem] To provide a metal sheet for a battery container which employs a rolled metal sheet and with which it is possible to suppress cracking of a base material and peeling of resin even if a deep drawing process employing a small corner portion radius is used, and to provide a method of manufacturing said metal sheet for a battery container. [Solution] This metal sheet for a battery container is a metal sheet that is used for a battery container and that comprises iron or an alloy of iron, characterized in that the thickness of the metal sheet is 10 to 100 µm, the tensile strength of the metal sheet is 300 to 700 MPa, the elongation of the metal sheet is 5 to 35%, and the ratio between the grain size of the metal sheet in the planar direction and the thickness direction is 0.8 to 8.

Description

Metal plate for battery container and method for producing the metal plate for battery container

The present invention relates to a metal plate suitable as a battery container such as a lithium ion secondary battery and a method for producing the metal plate for the battery container.

In recent years, downsizing of electronic devices has been remarkable, and portable electronic devices such as mobile phones and portable information terminals have been widely used. Such a portable electronic device is equipped with a rechargeable secondary battery as its power source.
Secondary batteries are not only installed in the above-mentioned portable electronic devices, but are also gradually installed in vehicles such as hybrid cars and electric cars due to gasoline exhaustion and environmental problems. Yes.

In the above-described secondary battery mounted on a portable electronic device or a vehicle, a lithium ion secondary battery (hereinafter also referred to as “LiB”) has attracted attention as a high-performance battery with high output and long life.
There are various types of lithium ion secondary batteries depending on the application, and battery containers that contain a non-aqueous electrolyte, a positive electrode active material, a negative electrode active material, and the like take various forms such as a cylindrical shape and a rectangular shape. Among these, Patent Document 1 discloses a technique for accommodating an electrode or the like in a pouch using a laminated metal plate in which a thin plate-like metal plate is coated with a resin. Further, according to this Patent Document 1, it is mentioned that iron or an iron alloy is used as a metal foil core material.

In Patent Document 2 and Patent Document 3, a rolled metal plate having a thickness of 200 μm or less is used, and Ni plating is applied to the rolled metal plate, and then rolling and heat treatment are performed on the surface of the rolled metal plate. A technique for forming a diffusion alloy layer containing Ni and Fe is disclosed. A polyolefin-based resin may be formed on a rolled metal plate in order to improve the corrosion resistance against an electrolytic solution, etc. According to this Patent Document 2, by using the diffusion alloy layer, the rolled metal plate and the polyolefin-based resin are formed. It is mentioned that the adhesion is improved.

JP 2001-202932 A International Publication No. 2016/013572 International Publication No. 2016/013575

Secondary batteries that can be mounted on the vehicles and electronic devices described above are required to have high capacity in addition to high output. Here, if it is sufficient to simply increase the capacity, it may be sufficient to accommodate a corresponding electrode active material in a relatively large container. However, particularly in a secondary battery mounted on a vehicle, an increase in the weight of the battery itself immediately leads to a deterioration in fuel consumption. Therefore, an increase in weight must be suppressed as much as possible even in order to realize a high capacity.

As a technique for realizing a high capacity while avoiding an increase in weight as much as possible, it is assumed that deep drawing under more severe conditions is performed to increase the internal capacity of the battery container. In particular, it is possible to increase the battery capacity by reducing the corner portion (corner) R of the battery container and matching the size of the battery container with a plurality of plate-like electrodes accommodated inside each other. However, the conventional techniques including the above-described Patent Documents 1 to 3 are not suitable for such deep drawing, and there is much room for improvement. In particular, at the corner (corner) of the battery container, it has been found that when deep drawing is performed under severe conditions, cracking of the substrate and peeling of the resin become significant.
An object of the present invention is to solve the above-mentioned problem as an example. For example, a battery capable of suppressing cracking of a base material and peeling of a resin even when deep drawing with a small corner R is performed using a rolled metal plate. It aims at providing the metal plate for containers, and the manufacturing method of this metal plate for battery containers.

In order to solve the above problems, a metal plate for a battery container according to the present invention is (1) a metal plate made of iron or an iron alloy used as a battery container, and the metal plate has a thickness of 10 to 100 μm. The tensile strength of the metal plate is 300 to 700 MPa, the elongation of the metal plate is 5 to 35%, and the ratio of the crystal grain size in the plane direction and the thickness direction of the metal plate is 0.8 to 8 It is characterized by being.
In the above (1) battery container metal plate, (2) it is preferable to have a surface treatment layer containing Cr or Ni on the metal plate.
In the metal plate for battery containers described in (1) or (2), it is preferable that (3) the metal plate is coated with a thermoplastic resin.

In the battery container metal plate described in (3) above, (4) the thermoplastic resin preferably contains a polyolefin resin or a polyester resin.
In the metal plate for battery containers described in (4) above, it is preferable that (5) the polyolefin resin or polyester resin covers both surfaces of the metal plate.
Moreover, in the metal plate for battery containers of (5) described above, (6) the polyolefin resin that covers one surface of the metal plate is a polypropylene resin, and the other surface of the metal plate is covered. The polyester-based resin is preferably a polyethylene terephthalate resin.

In the metal plate for battery containers described in (6) above, (7) the polyester resin is preferably non-oriented.
In the metal plate for battery containers according to any one of (3) to (7), (8) the thickness of the thermoplastic resin is preferably 10 to 50 μm.

Furthermore, in order to solve the above-described problems, a method for producing a metal plate for a battery container according to the present invention is a method for producing a metal plate for a battery container comprising a metal plate of iron or an iron alloy, and the metal plate is A first step of rolling to a thickness of 10 to 100 μm, and a second step of annealing the metal plate after the first step, wherein the metal plate has a tensile strength of 300 to 700 MPa, and the metal plate The metal plate is softened so that its elongation is 5 to 35% and the ratio of the crystal grain size in the plane direction to the thickness direction of the metal plate is 0.8 to 8.
In addition, in the manufacturing method of the above-mentioned metal plate for battery containers, it is preferable to have the 3rd process of forming a surface treatment layer in the said metal plate after the said 1st process and before or after the said 2nd process.

According to the present invention, cracking of the substrate and peeling of the resin can be suppressed even when deep drawing with a small corner R is performed using a rolled metal plate.

It is a schematic diagram which shows the metal plate for battery containers concerning embodiment. It is a flowchart which shows the manufacturing method of the metal plate for battery containers concerning embodiment. Material No. photographed with a microscope It is a cross-sectional photograph in A. It is a figure which shows the outline | summary of the battery container shape | molded using the metal plate for battery containers concerning embodiment. Material No. photographed with a microscope It is a cross-sectional photograph in E.

Hereinafter, the metal plate 1 for battery containers of this embodiment is demonstrated using FIG. In FIG. 1, for convenience, the thickness direction of the battery container metal plate 1 is described as the Z direction, and the rolling direction of the battery container metal plate 1 is described as the X direction. However, the definition of these directions does not reduce the scope of rights of the present invention.
<Metal plate for battery container>
The battery container metal plate 1 according to the present embodiment is made of iron or an iron alloy. Examples of iron alloys include various steel plates that can be used as a base material for battery containers. For example, low-carbon aluminum killed steel (carbon content 0.01 to 0.15% by weight), carbon content 0.003% by weight The following ultra-low carbon steel or non-aging ultra-low carbon steel obtained by adding Ti or Nb to ultra-low carbon steel is also included.
In addition, the thickness of the battery container metal plate 1 according to the present embodiment is 10 to 100 μm, more preferably 15 to 60 μm. If the thickness is less than 10 μm, the quality tends to be unstable, such as pinholes occurring in the cold rolling process or unstable thickness difference. Moreover, a crack generate | occur | produces in a shaping | molding process and there exists a possibility that the effect made into the objective of this application may not be acquired. On the other hand, if the thickness exceeds 100 μm, the effect of weight reduction cannot be obtained.

Here, an example of a component composition in the case where the metal plate 1 for battery containers is an iron alloy is shown below.
(C: 0.0001 to 0.1% by weight)
C is an element that increases the strength of the metal plate 1 for battery containers. If the C content is excessive, the strength increases excessively and the rollability decreases, so the upper limit of the C content is set to 0.1% by weight. On the other hand, the lower limit value of the C content is not particularly limited, but considering the cost, the lower limit value of the C content is set to 0.0001% by weight. The C content is more preferably 0.001 to 0.01% by weight.

(Si: 0.001 to 0.5% by weight)
Si is an element that increases the strength of the metal plate 1 for battery containers. If the Si content is excessive, the strength increases excessively and the rollability decreases, so the upper limit of the Si content is set to 0.5% by weight. On the other hand, the lower limit value of the Si content is not particularly limited, but considering the cost, the lower limit value of the Si content is set to 0.001% by weight. The Si content is more preferably 0.001 to 0.02% by weight.

(Mn: 0.01 to 1.0% by weight)
Mn is an element that increases the strength of the metal plate 1 for battery containers. If the Mn content is excessive, the strength increases excessively and the rollability decreases, so the upper limit of the Mn content is 1.0% by weight. On the other hand, the lower limit of the Mn content is not particularly limited, but considering the cost, the lower limit of the Mn content is set to 0.01% by weight. The Mn content is more preferably 0.01 to 0.5% by weight.

(P: 0.001 to 0.05% by weight)
P is an element that increases the strength of the metal plate 1 for battery containers. If the P content is excessive, the strength increases excessively and the rollability decreases, so the upper limit of the P content is 0.05% by weight. On the other hand, the lower limit value of the P content is not particularly limited, but considering the cost, the lower limit value of the P content is 0.001% by weight. The P content is more preferably 0.001 to 0.02% by weight.

(S: 0.0001 to 0.02% by weight)
S is an element that reduces the corrosion resistance of the metal plate 1 for battery containers. Therefore, the smaller the S content, the better. In particular, when the S content exceeds 0.02% by weight, the corrosion resistance decreases significantly, so the upper limit of the S content is 0.02% by weight. On the other hand, the lower limit of the S content is not particularly limited, but considering the cost, the lower limit of the S content is set to 0.0001% by weight. The S content is more preferably 0.001 to 0.01% by weight.

(Al: 0.0005 to 0.20% by weight)
For example, Al is added as a deoxidizing element of the metal plate 1 for battery containers. In order to obtain the effect of deoxidation, the Al content is preferably 0.0005% by weight or more. However, if the Al content is excessive, the rollability deteriorates, so the upper limit of the Al content is 0.20% by weight. On the other hand, the lower limit value of the Al content is not particularly limited, but considering the cost, the lower limit value of the Al content is set to 0.0005% by weight. The Al content is more preferably 0.001 to 0.10%.

(N: 0.0001 to 0.0040% by weight)
N is an element that reduces the workability of the metal plate 1 for battery containers. Therefore, the smaller the N content, the better. In particular, when the N content exceeds 0.0040% by weight, the workability deteriorates significantly, so the upper limit of the N content is set to 0.0040% by weight. On the other hand, the lower limit value of the N content is not particularly limited, but the lower limit value of the N content is set to 0.0001% by weight in consideration of cost. The N content is more preferably 0.001 to 0.0040% by weight.

(Balance: Fe and inevitable impurities)
The main element of the balance of the metal plate 1 for battery containers is Fe, and the other is an impurity that is inevitably mixed during manufacture.

In addition, Ti, Nb, B, Cu, Ni, Sn, Cr, and the like may be contained as additional components. In particular, Ti and Nb have the effect of fixing C and N in the battery case metal plate 1 as carbides and nitrides and improving the workability of the battery case metal plate 1, so that Ti: 0.01 to One or two of 0.8 wt% and Nb: 0.005 to 0.05 wt% may be contained. Moreover, the metal plate 1 for battery containers which concerns on this embodiment has a more preferable steel plate whose Cr is 10.5% or less.

In addition, the metal plate 1 for battery containers which concerns on this embodiment is equipped with the following characteristics by annealing after cold-rolling. Note that the temperature and time required for annealing in this embodiment are 2 to 9 hours, more preferably 2 to 6 hours when the annealing is performed at 450 ° C. to 650 ° C. (more preferably 500 to 600 ° C.). When annealing is performed at 700 to 800 ° C., the required time is 20 to 120 seconds.
(Tensile strength)
The tensile strength of the metal plate 1 for battery containers according to the present embodiment is 300 to 700 MPa. When the tensile strength is less than 300 MPa, there is a problem that cracks and holes are generated due to deformation by an external force when used as a battery container, thereby causing leakage of the electrolyte. Moreover, it is because workability will become scarce when tensile strength exceeds 700 Mpa. The tensile strength of the battery container metal plate 1 is more preferably 350 to 650 MPa. When more workability is required, it is more preferably 350 to 450 MPa.
In addition, the tensile strength of the metal plate 1 for battery containers was performed according to the “metal material tensile test method” described in JIS standard Z2241.

(Elongation)
The elongation of the battery container metal plate 1 according to this embodiment is 5 to 35%. This is because if the elongation of the metal plate for battery container 1 is less than 5%, the workability is poor at the corners (corners), and cracks may occur during processing. Further, if the elongation is 36% or more, a high temperature and a long time are required as annealing conditions for obtaining such characteristics, and thus productivity is deteriorated. The elongation of the battery container metal plate is more preferably 5 to 20%. In particular, when the thickness of the metal plate 1 for battery containers is small, it is preferably 5 to 15%, more preferably 7 to 12%.
The elongation of the metal plate 1 for battery containers was performed according to “20: Elongation at break (%) A measurement formula (7)” in “Metal material tensile test method” described in JIS standard Z2241.

(Ratio of crystal grain size)
The ratio of crystal grain size in the planar direction (rolling direction) to the thickness direction (planar direction / thickness direction) of the metal plate for battery container 1 according to the present embodiment is 0.8 to 8. The “crystal grain size” in the present embodiment is an average value of crystal grain sizes present per unit area (for example, 1 μm × 1 μm). The method for measuring the average crystal grain size is not particularly limited. For example, after taking a cross-sectional photograph of a metal plate with a scanning electron microscope (SEM), it conforms to JIS G0551 (Appendix B or C). Can be measured. In order to obtain the ratio in the plane direction (rolling direction) and the thickness direction, the crystal grain size is obtained based on each of the test line along the plane direction and the test line along the thickness direction, and the ratio is calculated. In each of the plurality of particles to be measured, the ratio of the crystal grain sizes described above may be calculated by comparing the longest length value in the rolling direction with the longest length value in the thickness direction.
It is difficult in a general manufacturing method that the above-mentioned crystal grain size ratio of the metal plate 1 for battery containers is less than 0.8. Further, if the above-mentioned crystal grain size ratio exceeds 8, cracks are likely to occur during processing. The ratio of the crystal grain sizes of the metal plate 1 for battery containers is more preferably 0.8 to 5. When more workability is required, the above-mentioned crystal grain size ratio of the battery container metal plate 1 is more preferably 0.8-4.

<Surface treatment layer>
A surface treatment layer 2 may be formed on the battery plate metal plate 1 according to the present embodiment. As this surface treatment layer 2, for example, Cr plating or Ni plating may be mentioned for improving the adhesion with the resin formed thereon, and a single layer or multiple layers thereof may be used. Alternatively, a treatment layer for improving corrosion resistance (for example, Ni—Co plating treatment layer, Zn plating treatment layer such as Zn plating, Zn—Ni, Zn—Co plating, Sn plating treatment layer, and the like) A dispersion plating treatment layer between the base metal, a chemical conversion treatment layer for forming an oxide film, a silane coupling agent treatment layer, and the like may be provided. The surface treatment layer of this embodiment may be formed, for example, after the battery container metal plate 1 is annealed after cold rolling or after the battery container metal plate 1 is cold rolled. It is also possible to form it before it is done. Moreover, in FIG. 1, although the surface treatment layer 2 is formed in both surfaces of the metal plate 1 for battery containers, the aspect in which the surface treatment layer 2 is formed in at least one surface may be sufficient.

In addition, when performing Ni plating on the metal plate 1 for battery containers, after carrying out electrolytic degreasing and pickling of the cold-rolled metal plate by a normal method, for example, the Ni plating bath shown below is used as an example. it can. As the Ni plating bath, a nickel sulfate bath called a watt bath is mainly used, but a sulfamic acid bath, a borofluoride bath, a chloride bath, or the like may be used.
(Ni plating bath composition and conditions)
Nickel sulfate: 200-350 g / l
Nickel chloride: 20-60g / l
Boric acid: 10-50 g / l
pH: 1.5-5.0
Bath temperature: 40-70 ° C
Current density: 1 to 40 A / dm ²

The surface treatment layer 2 formed on the battery container metal plate 1 may be provided on at least the surface of the battery container metal plate 1 that will be the inner surface of the container, but may be formed on both the outer and inner surfaces of the container. May be. The nickel plating as the surface treatment layer 2 formed on the metal plate 1 for battery containers uses not only pure Ni but also an alloy containing Ni such as Ni—Co alloy or Fe—Ni alloy. It may be formed.
In addition, the thickness of the nickel plating of this embodiment is preferably 0.1 to 5 μm. Of these, the lower limit value is more preferably 0.3 μm, and even more preferably 0.5 μm. On the other hand, the upper limit value is more preferably 3 μm, and even more preferably 1 μm.
Further, when nickel plating is formed as the surface treatment layer 2 on the battery plate metal plate 1 and then heat treatment is performed, an Fe—Ni diffusion layer is formed. From the viewpoint of improving workability, the Fe—Ni diffusion layer is preferably 0.2 μm or more, and more preferably 0.5 μm or more.

In addition, when Cr plating is performed on the metal plate 1 for battery containers, the cold-rolled metal plate is electrolytically degreased and pickled by a normal method, and then, for example, the following Cr plating bath is used as an example. it can. In this case, the thickness of the Cr plating as the surface treatment layer 2 is preferably 0.05 to 1.0 μm.
(Cr plating bath composition, conditions)
CrO ₃ : 30 to 200 g / l
NaF: 5-10 g / l
Bath temperature: 35-65 ° C
Current density: 5 to 50 A / dm ²

<Thermoplastic resin>
The metal plate 1 for a battery container according to the present embodiment may be coated with a thermoplastic resin 3 on at least one surface. The thickness of the thermoplastic resin 3 is 10 to 50 μm, more preferably 10 to 30 μm.
Moreover, as the thermoplastic resin 3 of this embodiment, polyolefin resin, polyester resin, or polyamide resin is illustrated. And it is preferable that this polyolefin resin, polyester-type resin, or polyamide resin has coat | covered both surfaces of the metal plate 1 for battery containers. In this case, it is preferable that one surface (the inner surface side of the battery can) of the metal plate for battery container 1 is covered with a polypropylene resin. On the other hand, the other surface (the outer surface side of the battery can) of the metal plate for battery container 1 is preferably covered with a polyester resin, particularly polyethylene terephthalate. As the polyester resin, for example, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate and the like can be used in addition to polyethylene terephthalate. Further, modified resins such as urethane-modified polyester resin, acrylic-modified polyester resin, and epoxy-modified polyester resin may be used.

In addition, the thickness of the resin that covers one surface (for example, the inner surface side of the battery can) of the metal plate for battery container 1 and the thickness of the resin that covers the other surface (for example, the outer surface side of the battery can) are required. The thickness may be adjusted appropriately between the above thickness ranges depending on the corrosion resistance and workability, and the thicknesses on both sides may be the same or different.
Moreover, when using a polyester resin, it is preferable that this polyester resin is non-oriented.
Further, the other surface (the outer surface side of the battery can) of the battery container metal plate 1 is not limited to the above-described polyester resin (polyethylene terephthalate), and both surfaces of the battery container metal plate 1 may be covered with a polypropylene resin. Good. Or you may coat | cover both surfaces of the metal plate 1 for battery containers with a polyester resin.

Moreover, the form which has coat | covered the metal plate 1 for battery containers through the well-known adhesive agent may be sufficient as the thermoplastic resin 3. FIG. As the known adhesive, for example, an acid-modified polyolefin resin, an epoxy resin, an acrylic resin, a urethane resin, a silicon resin, a polyisobutylene resin, a fluororesin, or an inorganic adhesive such as water glass can be used.
The thermoplastic resin 3 may be laminated on the metal plate 1 for a battery container after forming a film, or the thermoplastic resin heated and melted may be formed into a film by a slit of an extrusion width of an extrusion molding machine. An extrusion lamination method in which extrusion is performed and lamination directly on the metal plate 1 may be used. When laminating after forming the film, the film is not particularly limited. For example, the film may be an unstretched film, a uniaxially stretched film, or a biaxially stretched film.

<Method for producing metal plate for battery container>
Next, a method for manufacturing the metal plate for a battery container according to this embodiment will be described with reference to FIG.
First, a metal plate made of iron or an iron alloy is prepared, and cold rolling is performed by putting the metal plate into a rolling machine that performs press working (step 1). As a result, the cold rolled metal plate 1 for battery containers having a thickness of 10 to 100 μm is formed. This cold rolling may be performed in multiple stages as necessary, and heat treatment may be performed in between.

Next, the battery container metal plate 1 is annealed (step 2). At this time, the temperature of the metal plate for battery container 1 in the annealing treatment is 450 to 650 ° C., more preferably 500 to 600 ° C. The time required for this annealing treatment is 2 to 9 hours, more preferably 2 to 6 hours. Further, when the annealing treatment is performed at 700 to 800 ° C., it can be performed for 20 to 120 seconds, but it is preferably performed in the former temperature range from the viewpoint of improving workability.

After step 2, the battery container metal plate 1 is preferably subjected to surface treatment (plating treatment) to form a surface treatment layer 2 on the battery container metal plate 1 (step 3). At this time, for example, a Ni plating layer is formed as the surface treatment layer 2 on the metal plate 1 for battery containers.
The thickness of the surface treatment layer 2 formed in step 3 is preferably, for example, 0.1 to 5 μm for the Ni plating layer and 0.05 to 1.0 μm for the Cr plating layer. The annealing in step 2 may be performed after the surface treatment layer 2 is formed. Further, after the surface treatment layer 2 is formed after the annealing in Step 2, for example, heat treatment may be further performed for the purpose of improving the workability of the Ni plating layer. The heat treatment conditions after the Ni plating can be performed under the same conditions as the annealing conditions described in Step 2.
In addition, when the rolling process of step 1 is performed after a plating process, a crack may arise on the surface of a Ni plating film, and adhesiveness and corrosion resistance may fall, and it is not preferable.

The metal plate for battery container 1 after passing through

steps

2 and 3 has a tensile strength of 300 to 700 MPa, an elongation of 5 to 35%, and the planar direction (rolling direction) and thickness direction of the metal plate 1 for battery container. The crystal grain size ratio is 0.8 to 8.

Next, in step 4, the battery container metal plate 1 on which the surface treatment layer 2 is formed is subjected to a treatment (resin coating treatment) for coating the thermoplastic resin 3 described above with a thickness of about 10 to 50 μm. . More specifically, a polypropylene resin is formed on one surface on the inner surface side of the metal plate 1 for battery containers, and a polyethylene terephthalate resin or a polypropylene resin is formed on one surface on the outer surface side of the container. . As described above, the resin may be formed by film lamination or extrusion lamination. The temperature of the battery container metal plate 1 when the thermoplastic resin 3 is coated is adjusted to 200 to 280 ° C.

In step 5, deep drawing is performed to form the battery container metal plate 1 into a container shape as shown in FIG. More specifically, the container shape of the present embodiment has a rectangular recess having a depth D in which corners with a radius of curvature R are formed at four corners so that a rectangular electrode plate can be accommodated. In the container of FIG. 4, the Rs at the four corners are equal, but the Rs at the four corners may be different from each other.

The battery container is sealed after housing battery elements such as an electrode plate and an electrolytic solution, but the battery container metal plate 1 of the present embodiment can also be applied as a lid member of a battery container used for sealing. The lid member which is a constituent member of such a battery container may be formed with a storage space similar to that of the battery container main body shown in FIG. 4, or may be used as a flat plate. Further, when sealing the battery container, it is preferable to heat-seal the lid member described above at the peripheral flange portion of the battery container main body having the drawn housing portion. In this case, it is preferable that the coating resin on the facing surfaces of the battery container body and the lid member is configured such that the same kind of resin faces each other like polypropylene resins or polyester resins. The above-described sealing method is an example, and is not limited thereto. For example, a known adhesive may be used.

Since the battery container obtained in this embodiment is formed using the battery container metal plate 1 of this embodiment described above, the adhesion between the nickel-plated metal plate or the chrome-plated metal plate and the resin. Therefore, it can be suitably used as a battery container for various primary batteries or secondary batteries such as alkaline batteries, nickel-metal hydride batteries, nickel-cadmium batteries, and lithium ion batteries.

Next, the present invention will be described more specifically with reference to examples. First, the material No. used in Examples or Comparative Examples described later is used. A to material No. The manufacturing conditions of the battery plate metal plate 1 for F are shown in Table 1 below.

<Material No. A>
Material No. As A, first, a cold rolled sheet (thickness 25 μm) of low carbon aluminum killed steel having the following chemical composition was prepared as a base material.
C: 0.04 wt%, Mn: 0.32 wt%, Si: 0.01 wt%, P: 0.012 wt%, S: 0.014 wt%, balance: Fe and inevitable impurities

Next, the prepared substrate was subjected to electrolytic degreasing and pickling by sulfuric acid immersion, and then Ni plating was performed under the following conditions to form a surface treatment (Ni plating) layer 2 having a thickness of 1.0 μm. The conditions for Ni plating were as follows.
(Nickel plating conditions)
Bath composition: Nickel sulfate, nickel chloride, boric acid, pit inhibitor pH: 4.0 to 4.6
Bath temperature: 60 ° C
Current density: 25-30 A / dm ²

The battery plate metal plate 1 having the following characteristics was obtained by annealing the substrate on which the Ni plating layer was formed at 600 ° C. for 3 hours.
・ Tensile strength: 390 MPa
・ Elongation: 10%
-Ratio of crystal grain size in the plane (rolling) direction and thickness direction: 1.2
As shown in FIGS. 3 and 5, the crystal grain size conforms to JIS G0551 (Appendix C) after taking a cross-sectional photograph of the metal plate 1 for a battery container with a scanning electron microscope (SEM). And it measured about each of the plane direction and the thickness direction.

Material No. Regarding B to E, the material no. Using the same base material as A, changing the plating conditions and heat treatment conditions as follows, the material No. B to E were prepared.

<Material No. B>
Material No. In B, material no. Instead of the nickel plating layer of A, a Cr plating layer as a surface treatment layer 2 having a thickness of 0.1 μm was formed under the following conditions.
(Chrome plating conditions)
Chromium plating bath: CrO ₃ : 100 g / l, NaF: 5 g / l
Bath temperature: 40 ° C
Current density: 50 A / dm ²

Thereafter, the material No. Similarly to A, annealing was performed at a temperature of 600 ° C. for 3 hours to obtain a metal plate 1 for a battery container having the following characteristics.
・ Tensile strength: 390 MPa
・ Elongation: 10%
-Ratio of crystal grain size in the plane (rolling) direction and thickness direction: 1.2

<Material No. C>
Material No. In C, material No. was changed except that the annealing condition was set at a temperature of 550 ° C. for 3 hours. In the same manner as A, a metal plate 1 for a battery container having the following characteristics was obtained.
・ Tensile strength: 390 MPa
・ Elongation: 11%
-Ratio of crystal grain size in the plane (rolling) direction and thickness direction: 3

<Material No. D>
Material No. In D, material No. was changed except that the annealing condition was set at 450 ° C. for 3 hours. In the same manner as A, a metal plate 1 for a battery container having the following characteristics was obtained.
・ Tensile strength: 630 MPa
・ Elongation: 5.5%
-Ratio of crystal grain size in the plane (rolling) direction and thickness direction: 5

<Material No. E>
Material No. In E, material No. except that the annealing condition was not performed. In the same manner as A, a metal plate 1 for a battery container having the following characteristics was obtained.
・ Tensile strength: 780 MPa
・ Elongation: 3%
-Ratio of crystal grain size in the plane (rolling) direction and thickness direction: 10

<Material No. F>
Material No. In F, a 25 μm-thick pure aluminum plate (O material of JIS H4000 alloy number A1050) having the following composition was used as the metal plate 1 for a battery container without providing a surface treatment layer and without performing an annealing treatment.

This material No. The characteristics of F are as follows. In addition, material No. For F, the crystal grain size was not measured.
・ Tensile strength: 60 MPa
・ Elongation: 5%

Next, the material no. A to material No. For the battery container metal plate 1 using F, a polypropylene resin is formed on one surface of the battery container metal plate 1 on the container inner surface side, and polyethylene terephthalate is formed on the one surface on the container outer surface side. Each resin was formed. In addition, the lamination temperature (temperature of the metal plate 1 for battery containers) at this time was 260 ° C.

(Processing into battery containers)
As shown in FIG. 4, the outer dimensions of the metal plate 1 for a battery container having the thermoplastic resin 3 formed on both sides as described above are as follows: vertical dimension H = 70 mm × horizontal W = 70 mm, and radius of curvature R at the four corners of the battery container. Were processed as 12.5, 15, 20, and 25 mm, respectively. At this time, the battery container was formed by drawing the depth D in the range of 4 to 17 mm.
It has been found that the value of D / R is important when the depth of the drawing process is D and the radius of curvature R when processing the battery container. More specifically, the larger the D / R value, the more severe the processing, but it becomes possible to form a battery container with a larger capacity. Based on such knowledge, the D / R value is preferably 0.4 or more, more preferably 0.9 or more. Thereby, the capacity | capacitance as a battery container can be enlarged.

(Evaluation method after processing)
The evaluation after processing was evaluated by visually observing cracks in the base material and floats and cracks in the thermoplastic resin at the four corners of the battery container.
The evaluation was performed based on the following criteria (the same applies to other examples and comparative examples described later).
[Evaluation criteria]
3 points: As a result of visual determination, no cracks in the base material and no floating / cracking in the thermoplastic resin were observed.
2 points: As a result of visual judgment, cracks and floats were partially observed although they could be put to practical use.
1 point: As a result of visual judgment, cracks in the base material and floating / cracking of the thermoplastic resin that were not practically used were observed.

<Example 1>
Material No. 1 shown in Table 1 as the metal plate 1 for battery containers. A was used. In addition, a polypropylene resin is formed with a thickness of 30 μm on one surface of the metal plate for battery container 1 on the inner surface side of the container, and a polyethylene terephthalate resin is formed with a thickness of 12 μm on one surface on the outer surface side of the container. Formed. In addition, the lamination temperature (temperature of the metal plate 1 for battery containers) at this time was 260 ° C.
And the depth at the time of a drawing process was 11 mm, and it processed into the battery container.
Table 2 shows the material specifications, drawing conditions, and evaluation of the processing results in Example 1.

<Example 2>
The same operation as in Example 1 was performed except that the depth during drawing was set to 15 mm.
Table 2 shows the evaluation of material specifications, drawing conditions, and processing results in Example 2.

<Example 3>
The same operation as in Example 1 was performed except that the depth during drawing was 17 mm.
Table 2 shows the material specifications, drawing conditions, and evaluation of the processing results in Example 3.

<Example 4>
The same procedure as in Example 1 was performed except that the thickness of the polyethylene terephthalate resin formed on the outer surface side of the battery container was 30 μm and the depth during drawing was 17 mm.
Table 2 shows the material specifications, drawing conditions, and evaluation of the processing results in Example 4.

<Example 5>
Example 1 except that the thickness of the polypropylene resin formed on the inner surface side of the battery container is 20 μm, the thickness of the polyethylene terephthalate resin formed on the outer surface side of the battery container is 30 μm, and the depth during drawing is 17 mm. As well as.
Table 2 shows the material specifications, drawing conditions, and evaluation of the processing results in Example 5.

<Example 6>
Material Nos. Shown in Table 1 as metal plates for battery containers. The same procedure as in Example 1 was performed except that B was used and the depth during drawing was 17 mm.
Table 2 shows the material specifications, drawing conditions, and evaluation of the processing results in Example 6.

<Example 7>
Material Nos. Shown in Table 1 as metal plates for battery containers. The same procedure as in Example 1 was performed except that C was used.
Table 2 shows the material specifications, drawing conditions, and evaluation of the processing results in Example 7.

<Example 8>
Material Nos. Shown in Table 1 as metal plates for battery containers. The same operation as in Example 1 was performed except that D was used and the depth at the time of drawing was changed to 5 mm.
Table 2 shows the material specifications, drawing conditions, and evaluation of the processing results in Example 8.

<Example 9>
The same operation as in Example 8 was performed except that the depth during drawing was 6 mm.
Table 2 shows the evaluation of material specifications, drawing conditions and processing results in Example 9.

<Example 10>
The same operation as in Example 8 was performed except that the depth at the time of drawing was set to 7 mm.
Table 2 shows the material specifications, drawing conditions, and evaluation of the processing results in Example 10.

<Example 11>
The same operation as in Example 8 was performed except that the depth at the time of drawing was 11 mm.
Table 2 shows the evaluation of material specifications, drawing conditions, and processing results in Example 11.

<Comparative Example 1>
Material Nos. Shown in Table 1 as metal plates for battery containers. The same procedure as in Example 1 was performed except that E was used and the depth during drawing was changed to 4 mm.
Table 2 shows the material specifications, drawing conditions, and evaluation of the processing results in Comparative Example 1.

<Comparative Example 2>
The same operation as in Comparative Example 1 was performed except that the depth during drawing was set to 5 mm.
Table 2 shows the material specifications, drawing conditions, and evaluation of the processing results in Comparative Example 2.

<Comparative Example 3>
The same operation as in Comparative Example 1 was performed except that the depth during drawing was 6 mm.
Table 2 shows the material specifications, drawing conditions, and evaluation of the processing results in Comparative Example 3.

<Comparative Example 4>
The same procedure as in Comparative Example 1 was performed except that the resin formed on the outer surface side of the battery container was a stretched polyethylene terephthalate resin having a thickness of 19 μm and the depth during drawing was 5 mm.
Table 2 shows the material specifications, drawing conditions, and evaluation of the processing results in Comparative Example 4.

<Comparative Example 5>
Material Nos. Shown in Table 1 as metal plates for battery containers. The same procedure as in Comparative Example 1 was performed except that F was used.
Table 2 shows the evaluation of material specifications, drawing conditions, and processing results in Comparative Example 5.

<Comparative Example 6>
The same operation as in Comparative Example 5 was performed except that the depth at the time of drawing was changed to 5 mm.
Table 2 shows the evaluation of material specifications, drawing conditions, and processing results in Comparative Example 6.

<Comparative Example 7>
The same operation as in Comparative Example 5 was performed except that the depth during drawing was 6 mm.
Table 2 shows the material specifications, drawing conditions, and evaluation of the processing results in Comparative Example 7.

As shown in Table 2, in Examples 1 to 11, good processing results could be obtained at the four corners of the battery can. This means that the space in which the power generating elements (electrode plates, spacers, electrolytic solution, etc.) are accommodated in the battery container can be secured to the maximum while the corrosion resistance against the electrolytic solution and the adhesion between the resin and the substrate are secured.
On the other hand, in Comparative Examples 1 to 7, it was found that the smaller the radius of curvature, the worse the processing result, and it did not have the characteristics to withstand practical use.

Further, the inventors pay attention to the relationship between the drawing depth D and the radius of curvature R at the four corners of the battery can, and the ratio of these (the ratio of the drawing depth D to the radius of curvature R (D / R )). D / R can represent the degree of processing, and the greater the depth D, the smaller the R, that is, the greater the D / R, the more severe the processing. These ratios (D / R) when the radius of curvature R is changed (R12.5, R15, R20, and R25) are summarized in Table 3 below.
Further, the total thickness (μm) of the battery case metal plates used in Examples 1 to 11 and Comparative Examples 1 to 7, and the ratio (D / R) of the ratio of the drawing depth to the radius of curvature R (D / R) Table 3 also summarizes the ratio of sheet thickness / drawing depth D and radius of curvature R).

Based on Table 3, it can be said that the present invention has the following features.
(A) With the same plate thickness, processing is possible even if the ratio (D / R) between the drawing depth D and the radius of curvature R is 0.4 or more under the conditions specified in the embodiment. It has been demonstrated that a D / R of at least 1.4 is possible in .about.6. This suggests that, for example, in the case of a container shape having a radius of curvature R of 5 mm at the corner of the battery container, the drawing depth D can be formed up to about 7 mm. On the other hand, under the conditions defined in the comparative example, the limit (D / R) between the drawing depth and the radius of curvature R is 0.3.

(B) With respect to the relationship between the total plate thickness, the ratio of the depth of drawing and the ratio (D / R) of the radius of curvature R, it may be possible to process at least 0.05 or more under the conditions specified in the examples. Proven. On the other hand, under the conditions specified in the comparative example, the processing becomes difficult unless the value is 0.28 or more.

As described above, the metal plate for battery containers and the manufacturing method thereof according to the present invention can exhibit good characteristics even when deep drawing with a small radius of curvature R is performed using a rolled metal plate. It can be applied to a wide range of industries that use batteries.

1 Metal plate for battery container 2 Surface treatment layer 3 Thermoplastic resin

Claims

A metal plate made of iron or an iron alloy used as a battery container,
The metal plate has a thickness of 10 to 100 μm;
The tensile strength of the metal plate is 300 to 700 MPa,
The elongation of the metal plate is 5 to 35%, and
A metal plate for a battery container, wherein a ratio of a crystal grain size in a plane direction and a thickness direction of the metal plate is 0.8 to 8.
The metal plate for a battery container according to claim 1, further comprising a surface treatment layer containing Cr or Ni on the metal plate.
The metal plate for a battery container according to claim 1 or 2, wherein the metal plate is coated with a thermoplastic resin.
The metal plate for a battery container according to claim 3, wherein the thermoplastic resin includes a polyolefin resin or a polyester resin.
The metal plate for a battery container according to claim 4, wherein the polyolefin resin or polyester resin covers both surfaces of the metal plate.
The polyolefin resin covering one surface of the metal plate is a polypropylene resin,
The metal plate for a battery container according to claim 5, wherein the polyester resin covering the other surface of the metal plate is polyethylene terephthalate.
The metal plate for a battery container according to claim 6, wherein the polyester resin is non-oriented.
The metal plate for a battery container according to any one of claims 3 to 7, wherein the thickness of the thermoplastic resin is 10 to 50 µm.
A method for producing a metal plate for a battery container comprising a metal plate of iron or an iron alloy,
A first step of cold rolling the metal plate to a thickness of 10 to 100 μm;
A second step of annealing the metal plate after the first step;
The metal plate is softened so that the tensile strength of the metal plate is 300 to 700 MPa, the elongation of the metal plate is 5 to 35%, and the ratio of the crystal grain size in the plane direction and the thickness direction of the metal plate is 0.8 to 8. The manufacturing method of the metal plate for battery containers characterized by the above-mentioned.
The method for producing a metal plate for a battery container according to claim 9, further comprising a third step of forming a surface treatment layer on the metal plate after the first step and before or after the second step.