WO2001034876A1

WO2001034876A1 - Surface-treated steel sheet for battery case, battery case using it, battery using the case

Info

Publication number: WO2001034876A1
Application number: PCT/JP2000/007947
Authority: WO
Inventors: Hitoshi Ohmura; Tatsuo Tomomori; Hideo Ohmura
Original assignee: Toyo Kohan Co., Ltd.
Priority date: 1999-11-11
Filing date: 2000-11-10
Publication date: 2001-05-17
Also published as: AU1306501A

Abstract

Surface-treated steel sheet for a battery case, small in internal resistance and capable of maintaining a discharge level for a long time; a battery case; and a battery comprising them. The surface-treated steel sheet comprises a bismuth layer to be included in the outermost layer on the inner side of a battery case; or a bismuth layer to be formed on the outermost layer on the inner side of a battery case.

Description

Description Surface treated steel sheet for battery case, battery case using the same, battery using the case Technical field

TECHNICAL FIELD The present invention relates to a treated steel sheet for a battery case, and particularly to an alkaline manganese battery or the like.

The present invention relates to a surface-treated steel sheet used for a case of a tertiary battery, and further relates to a battery case and a battery using the surface-treated steel sheet. Background art

In recent years, the performance of portable home appliances has been remarkably improved, and as a result, batteries used in these devices have been required to have increasingly sophisticated and high-performance products. Conventionally, as the steel sheet used for the above-mentioned battery case, a method in which nickel-plated steel sheet is press-formed or a cold-rolled steel sheet is press-formed and then nickel-plated which easily adheres to the steel sheet surface is sometimes used. There were many.

Therefore, after that, in order to further improve the battery performance, / 5 adhesion between the inner surface of the case and the positive electrode mixture was increased, and at the same time, nickel-phosphorus alloy or nickel-tin diffusion, etc. Various methods have been proposed to reduce the internal resistance after the hard layer is formed.

In this case, although the nickel-tin diffusion layer is excellent in reducing the internal resistance, there is a problem that the discharge characteristics are deteriorated by D while the alloy layer is in contact with the alkaline solution for a long time. .

Therefore, the adhesion to the case steel sheet is good, and the adhesion to the positive electrode mixture is good, which is comparable to that of the nickel-tin diffusion layer. Also, if a metal or alloy material that does not deteriorate the discharge characteristics is selected and used, it can be expected that the above problems will be solved and the battery life will be improved. Disclosure of the invention

The present invention is characterized in that the plating layer components are not eluted into the alkaline solution even if the bismuth metal is in contact with the alkaline solution for a long time because of its excellent alkali resistance. However, this metal has been focused on that a diffusion layer can be easily formed because the metal is easily diffused, and a metal containing bismuth is used for the inner surface of the battery case by utilizing such a property. Thus, a battery whose discharge characteristics do not deteriorate for a long time is provided.

The surface-treated steel sheet for a battery case of the present invention is characterized in that a bismuth layer is formed on the outermost surface of the surface inside the battery case.

(0 In this case, it is desirable that the bismuth layer is formed by electrolytic plating.

The surface-treated steel sheet for a battery case of the present invention is characterized in that a nickel layer is formed as a lower layer and a bismuth layer is formed as an upper layer on a surface inside the battery case. The surface-treated steel sheet for a battery case of the present invention is characterized in that an iron-nickel diffusion layer is formed on the inner side of the battery case, a nickel layer is formed as an intermediate layer, and a bismuth layer is formed on the upper layer. Features.

In this case, it is desirable that the nickel layer is formed of a matte nickel plating layer, a semi-bright nickel plating layer, or a bright nickel plating layer.

The surface-treated steel sheet for a battery case of the present invention is characterized in that a bismuth layer is formed on the outermost layer on the inner side of the battery case.

In this case, the bismuth layer is desirably formed by electrolytic plating. The surface-treated steel sheet for a battery case of the present invention is characterized in that a nickel layer is formed as a lower layer and a bismuth layer is formed as an upper layer on a surface inside the battery case. The battery case of the present invention is characterized in that, on the inner side of the battery case, a 12-inch iron diffusion layer is formed as a lower layer, a nickel layer is formed as an intermediate layer, and a bismuth layer is formed as an upper layer. Features.

The battery of the present invention is a battery using the battery case according to any one of claims 6 to 10. BEST MODE FOR CARRYING OUT THE INVENTION

Since the surface-treated steel sheet of the present invention has good adhesion between the steel sheet and the bismuth layer, when used as a battery case, the battery performance is less deteriorated. In addition, since the elution of the components is extremely small even after being in contact with the alkaline solution for a long time, it is possible to provide a battery with little discharge deterioration.

The details of the present invention will be described below.

(1) Steel plate

In order to manufacture the surface-treated steel sheet of the present invention, it is necessary to first prepare a mild steel sheet. Soft

15 Steel sheets include cold-rolled low-carbon A1 killed steel sheets, ultra-low carbon steel sheets with a carbon content of 0.003% or less, and non-aging ultra-low steel sheets with the addition of niobium, boron, titanium, etc. A carbon steel plate or the like is preferably used. The reason why these mild steel sheets are used is that the ironing process for manufacturing the battery case can be easily performed in the subsequent processing operation. The thickness of the mild steel sheet used is about 0.10 mm to 0.40 mm

10 degrees is preferred. This is to facilitate subsequent battery case molding by the DI and DTR methods.

(2) Nickel plating

At least one surface of the steel plate is plated with nickel. As the nickel plating method, any of conventionally known methods of electroless plating and electrolytic plating can be used.

Z5 "Further, as the electrolytic plating, there are known baths such as a bath, a sulfamic acid bath, and a borofluoride bath, and any plating bath can be used. The surface may be matte, semi-glossy or glossy. The thickness of the nickel plating is preferably about 1 to 10 m. The reason for applying the nickel plating is to improve the adhesion of the bismuth plating applied thereon, so that the thickness of the nickel plating is 10 m or less is sufficient. On the other hand, if the thickness is less than 1, the diffusion layer formed by the subsequent heat treatment becomes difficult, so that 1 μm or more is necessary.

(3) Diffusion layer formation

After the nickel plating, heat treatment may be performed to form an iron-nickel diffusion layer. The purpose of the heat treatment for forming the iron-nickel diffusion layer is to prevent the surface treatment layer formed on the steel sheet from being easily separated from the case at the time of forming the battery case later.

The heat treatment is preferably performed under a non-oxidizing or reducing protective gas from the viewpoint of preventing oxide film formation. As the non-oxidizing gas, a so-called inert gas such as nitrogen, argon, or neon is preferably used. On the other hand, as the reducing gas, hydrogen, ammonia gas and the like are preferably used. Examples of the heat treatment method include a box annealing method and a continuous annealing method, and any method may be used. The heat treatment temperature is preferably at least 300 ° C., and the treatment time is preferably from about 30 seconds to about 10 hours. Such heat treatment conditions are also affected by the type of steel sheet. For example, when using an ultra-low carbon steel sheet having a carbon content of 0.003 wt% or less, it is desirable to perform the treatment at a high temperature for a short time because the recrystallization temperature of the steel base is high.

(4) Bismuth plating

Bismuth is applied on the nickel plating or iron-nickel diffusion layer. Bismuth plating can be performed in any known plating bath such as a perchloric acid bath, a pyrophosphoric acid bath, a citric acid bath, a metasulfonic acid bath, and a chloride bath. In general, baths containing organic substances often require strict bath management and have the problem of being expensive, but as long as the plating film is kept extremely thin as in the present invention, The drawbacks mentioned above are not very problematic.

In chloride bath, bismuth chloride: 80-120 / L, sodium chloride: 15-

20 gZL and hydrochloric acid: only about 20 Om 1 ZL, the composition of the bath should be simple, and it is necessary to provide a polarity cycle that uses the cathode for 10.5 seconds and then the anode for 5 seconds. If nickel strike plating is applied, the nickel layer will dissolve when the body is immersed in the bath and the body will be immersed during the anode cycle. It is necessary to keep in mind that there are problems such as the necessity of a complicated process.

In the case of methanesulfonic acid bath is to use what final by dissolving bismuth oxide methanesulfonic acid (0 to B i ^{3 +} is set to be 2 defined as and the free acid concentration at 20 GZL as the basic bath composition It is desirable to use a dispersant and a brightener selectively.

It is desirable to use, for example, polyethylene glycol nonylphenyl ether as the dispersant, and to use a 20% solution of an amine aldehyde as a brightener. The reason for using the brightener is that the use of the brightener can prevent the plated surface from becoming powdery. By adding the brightener, the cathode potential shifts to the hydrogen generation potential, the crystal structure on the plated surface can be refined, and the appearance of the plated surface can be improved.

In order to obtain the above-mentioned effects, it is preferable that the composition of the brightener is 10 to 1.5 parts by volume with respect to 1 part by weight of the dispersant. However, such an effect is hardly obtained. The working temperature of this bath is preferably 20 to 25, and the current density is preferably in the range of ² to 5 AZdm2. When using this plating bath, the thickness of the bismuth plating layer is usually preferably about 0.01 to 1.0 m. The thickness of the plating layer can be adjusted by the plating time.

To form a bismuth plating layer on a steel sheet, apply nickel plating on both sides of the steel sheet, and then apply bismuth plating only on the inside surface of the battery case. Nickel plating on both sides The method of applying bismuth on both surfaces later and the method of applying heat treatment after nickel plating and applying bismuth after forming the iron-nickel diffusion layer can be appropriately selected depending on the purpose of the product. Depending on the purpose, bismuth can be diffused into nickel by heat treatment. In this case, the bismuth layer is a layer containing bismuth as a main component. In the present invention, the bismuth layer is also referred to as a bismuth layer.

(5) Battery case formation

The battery case is processed by applying a draw forming method, a DI (draningan) dignite forming method, a DTR (dranginthinin adndredaw) forming method, or the like.

! 0 In the case of the DI molding method, first prepare a shallow draw cup material whose diameter is slightly larger than the outer diameter of the battery case as the finished product. This is sequentially supplied to a plurality of ironing dies arranged in multiple stages on the same axis so as to reduce the ironing aperture diameter, and is pressed by a punch having a rounded end to avoid constriction. Let through.

15 In the case of the DTR molding method, as in the case of the DI molding method, prepare a shallow drawn cup and redraw the cup to form a redrawn cup that is smaller in diameter and higher in height than the first shallow drawn cup. It is formed sequentially. That is, redrawing is performed by holding the ring-shaped holding member inserted into the cup and the redrawing die below the ring so that the redrawing punch can reciprocate in the holding member coaxially with the die. Placed

Therefore, re-drawing punches with different diameters will be used sequentially. The method of forming the battery case is not limited to the above method, and other methods can be applied.

(6) Manufacture of alkaline and manganese dry batteries

The positive electrode mixture contained in the alkaline manganese dry battery is prepared by mixing manganese dioxide, carbon powder, an alkaline aqueous solution, and the like. Since manganese dioxide is a source of oxidizing components, it is desirable to use manganese dioxide with high activity and high purity. Therefore, it is preferable that Mn_〇 ₂ uses 91% or more electrolytic manganese dioxide. The properties required for carbon powder are high purity and chemical stability, and good conductivity, mixability and liquid retention. Examples of carbon powders that meet these requirements include acetylene black, various types of modified carbon black, graphitized carbon black, and synthetic graphite powder. In recent years, synthetic graphite powder has been used exclusively.

5 To produce a positive electrode mixture, for example, electrolytic manganese dioxide and graphite powder are mixed in a weight ratio of 5: 1 to 10: 1, and an aqueous potassium hydroxide solution is further added and kneaded. A method such as a positive electrode mixture is applied.

On the other hand, in order to improve the conductivity between the battery case surface-treated steel sheet and the positive electrode mixture, a mixture of graphite powder, a thermosetting resin, and an organic solvent such as methyl ethyl ketone is sprayed on the inner surface of the battery case. It is also preferably applied that the composition is applied by the above method and dried.

Next, the positive electrode mixture is press-pressed in a mold to form a donut-shaped positive electrode mixture pellet, which is inserted and crimped inside the battery. Also, in order to mount the negative electrode plate with the negative electrode current collector rod spot-welded in the battery case, a predetermined position below the opening end of the battery case is net-in processed.

The separator used in IB batteries prevents the negative electrode active material and the product and the particles of the positive electrode active material from reciprocally moving, preventing the negative electrode product from being generated in the separator, preventing internal short-circuiting and self-discharge of the battery. For example, a fibrous or non-woven fabric having alkaline resistance is used. Examples of the material include synthetic resin products such as vinylon, polyolefin, and polyamide, or containing α-cellulose component.

Linter pulp, mercerized wood pulp or recycled cell mouth with a volume of 98% or more is used.

The above separator is inserted along the inner periphery of the positive electrode mixture pellet pressed into the battery case. Next, a negative electrode gel made of potassium hydroxide saturated with zinc particles and zinc oxide is inserted into the battery case. The zinc particles used in this case are preferably atomized powder having a center diameter of about 2S00〃m. As the gel material, starch, cellulose derivative, polyacrylate and the like can be used. After this, the anode body Attach an insulator gasket to the battery case, insert it into the battery case, and caulk it to form an alkaline manganese dry battery.

Example

Hereinafter, the present invention will be described in more detail based on examples.

5 "[Examples 1 to 6]

An annealed, temper-rolled cold-rolled steel sheet with a thickness of 0.25 mm, C: 0.03 wt%, Mn: 0.21 wt%, Si: 0.01 wt%, P : 0.01wt%, S: 0.06wt%, Al: 0.035wt%, N: 0.0024wt% were used as plating original sheets. This steel sheet was immersed in an aqueous solution at 70 ° C. in which 30/10 L of Na〇H was dissolved, treated with a current density of 5 AZdm ² for 10 seconds, and subjected to alkaline electrolytic degreasing. After alkaline degreasing, the steel plate was immersed in an aqueous solution of sulfuric acid (50 gZL) for 15 seconds to neutralize it by pickling, and then the steel sheet was stirred with air using a nickel pellet attached to a polypropylene bag as the anode and the following conditions. A matte nickel plating was applied. To the following matte nickel plating bath, add saccharin as a brightening agent / 5- to 5 and add bright nickel plating, or as a semi-brightening agent unsaturated carboxylic acid formaldehyde, polyoxy-ethylene adduct, nitrogen-containing heterocyclic compound or Nitrogen-containing aliphatic compounds were added to perform semi-gloss nickel plating. The amount of addition was appropriately determined while observing the appearance of the surface-treated steel sheet.

Nickel plating conditions

2ί) Bath composition Nickel sulfate: 300 g / L

Nickel chloride: 45 gZL

Boric acid: 45 gZL

Pitless agent: 0.5 gZL

pH 4.0 ± 0.2

^ Bath temperature 58 ± 2 ° C

Current density 2 5 A dm ² After nickel plating, heat treatment was performed at 450 to 600 ° C using a box-type annealing furnace to form an iron-nickel diffusion layer. The atmosphere gas in this case was hydrogen: 6%, the balance was nitrogen gas, and the dew point temperature was -45 ° C.

Next, bismuth plating was performed in the following bismuth chloride bath.

Bismuth plating conditions

Bath composition Metasulfonic acid 1 50 g / L

B i ^{2 +} 20 g / L

Dispersant 10 g / L

Brightener 1 Om 1 / L

(0 PH 0.7

Bath temperature 22 ± 2 ° C

Current density 3 A / dm ²

Table 1 summarizes the thickness of nickel plating, heat treatment conditions, and the thickness of bismuth plating. A battery case was manufactured by the DI forming method using the above surface-treated steel sheet. After cutting a surface-treated steel sheet with a thickness of 0.25 mm from a blank diameter of 41 mm to a diameter of 20.5 mm, redrawing and two-stage ironing are performed with a DI molding machine, and the outer diameter is 13.8 mm. The case wall was 0.20 mm and the height was 56 mm. After that, the upper part was finally trimmed to make a battery case for LR-6 type with a height of 49.3 mm. Next, the battery case is filled with the positive electrode active material and

A battery was prepared as described above, and the battery performance was measured.

First, manganese dioxide and graphite were collected at a weight ratio of 10: 1, and mixed with 8 mol potassium hydroxide to prepare a positive electrode mixture. On the other hand, a mixture of 80 parts by weight of graphite and 20 parts by weight of a thermosetting epoxy resin was diluted with methyl ethyl ketone, and the diluted solution was sprayed on the inner surface of the battery case and heated at 150 ° C for 15 minutes. Dried.

S The positive electrode mixture was press-pressed in a mold to form a donut-shaped mixture pellet, which was inserted into the battery case and crimped. In addition, the negative electrode plate obtained by spot welding the negative electrode In order to mount the battery case in the pond case, a specified position under the opening end of the battery case was necked in. Next, a separator made of nonwoven fabric made of vinylon is inserted along the inner periphery of the pellet pressed into the battery case, and a negative electrode gel made of a hydroxylating rim saturated with zinc particles and zinc oxide is inserted into the battery case. Was inserted. In addition, an insulator gas is attached to the negative electrode body.

After mounting the 5 "cassette, inserting it into the battery case, it was further caulked to obtain a finished alkaline-manganese dry battery. Table 2 shows the results of measuring the internal resistance, short-circuit current value, and continuous discharge time (min) of 2 ohms after standing at C for 20 days.

(Examples 7 to 9)

/ 0 Matte nickel plating was performed in the same manner as in Example 1, except that a surface-treated steel sheet having the same quality and the same thickness as in Example 1 was used. In this case, the thickness of the plating layer was adjusted by changing the plating time. Table 1 summarizes the plating layer thickness and heat treatment conditions. After the end of the nickel plating, a heat treatment was performed at 450 to 600 ° C. using a box-type annealing furnace to form an iron-nickel diffusion layer. In this case, the atmosphere gas was hydrogen: 6%, the balance was i-nitrogen gas, and the dew point temperature was set to 144 ° C.

Next, bismuth plating was performed in a bismuth chloride bath. Table 1 summarizes the thickness of bismuth plating. Table 2 summarizes the battery characteristics of Al-Mn-manganese dry batteries manufactured using this surface-treated steel sheet in the same manner as in Example 1. (Comparative Examples 1 to 3)

20 Table 1 summarizes the properties of steel sheets when only nickel plating was performed using steel sheets of the same quality and thickness as in Example 1. Table 2 summarizes the battery characteristics when fabricated using this steel sheet. Comparative Examples 1 and 2 show a case without heat treatment, Comparative Example 3 shows a case with heat treatment, and Comparative Example 3 shows an example with heat treatment at 550 ° C. for 300 minutes. Table 1 shows the properties and cross-sectional state of the steel sheet after the plating treatment and the heat treatment, and the internal resistance etc. of the alkaline manganese dry battery manufactured using the treated steel S sheet in the same manner as in Example 1. Table 2 summarizes the measured results. Table l Thickness of plating layer and heat treatment conditions

Example Heat treatment condition of Ni plating of the pond Β i Thickness of the plating or the surface side Comparative example or a Coarse ma Ma, force π ** l i Eye contact "i

Outer surface (n> CC) (min) Inner surface Matte Ni 10.1 Example 1

Outer surface matte Ni 2 One inner surface semi-gloss Ni 2 0.3 Example 2

Outer surface semi-gloss Ni 3 One inner surface gloss Ni 30.5 Example 3

Outer surface glossy Ni 4 ― Upper surface matte Ni 30.7 Example 4

Outer side gloss Ni 3 One side matte Ni 2 1.0 Example 5

Outer surface semi-gloss Ni 3 One inner surface semi-gloss Ni 3 0.001 Example 6

Outer side glossy Ni 5-Inner side matte Ni 10.5 Example 7 4 O U U

Outer side matte Ni 2-內 side semi-gloss Ni 20.8 Example 8 n π π

Outer side semi-gloss Ni 3-Inner side gloss Ni 61.0 Example 9 5 5 0 3 0 0

Outer side gloss Ni 10

Inner surface Semi-gloss Ni 2

Comparative Example 1

Outer side semi-gloss Ni 3

Inner half, glossy i 2

Comparative Example 2

Outer side gloss Ni 2

Inner surface gloss Ni 6

Comparative Example 3 5 5 0 3 0 0

Outer side gloss Ni 10

Table 2 Battery characteristics

[0035]

The characteristics of the steel sheet and the battery characteristics in the examples and comparative examples were measured as follows.

(1) Internal resistance

A frequency of 1 kHz is applied to the manufactured batteries by the AC impedance method. The characteristics of the surface-treated steel sheet and the characteristics of the battery in Examples and Comparative Examples were measured as follows.

(1) Internal resistance

A frequency of 1 kHz was applied to the manufactured dry battery by an AC impedance method, and the impedance at that time was measured, which was defined as an internal resistance value.

(2) Short circuit current

An ammeter was connected to the fabricated dry battery to provide a closed circuit, the current value of the dry battery was measured, and this was defined as the short-circuit current. The battery characteristics after being left at 60 ° C for 20 days are considered to be close to the performance of commercial batteries.

(3) Continuous discharge time

A closed circuit was created using the battery and a 2-ohm resistor, and the elapsed time until the voltage reached 0.9 V was measured. Industrial applicability

As can be seen from Table 2, the alkaline-manganese dry battery using a surface-treated steel sheet with a bismuth layer for the battery case has a higher internal resistance than the conventional alkaline-manganese dry battery using a nickel-plated steel sheet. It is recognized that there is a small difference in the short-circuit current value, and that there is also a significant difference in the discharge duration from the conventional alkaline manganese dry battery.

Claims

The scope of the claims

I. A surface-treated steel sheet for a battery case with a bismuth layer formed on the outermost layer on the inner side of the battery case.

{circle around (2)} The surface-treated steel sheet for a battery case according to claim 1, wherein the bismuth layer is formed by electrolytic plating.

3. A surface-treated steel sheet for a battery case that has a nickel layer as the lower layer and a bismuth layer as the upper layer on the inner surface of the battery case.

4. inside the surface from the battery case, iron nickelous diffusion layer as the lower layer, an intermediate layer and _{/ 0} to the nickel layer, the battery case for surface treated steel handling bismuth layer is formed as an upper layer.

5. The surface-treated steel sheet for a battery case according to claim 3, wherein the nickel layer comprises a matte nickel plating layer, a semi-bright nickel plating layer, or a bright nickel plating layer.

15- 6. A battery case with a bismuth layer formed on the innermost surface of the battery case.

7. The battery case according to claim 6, wherein the bismuth layer is formed by electrolytic plating.

8. A battery case with a nickel layer as the lower layer and a bismuth D layer as the upper layer on the inner surface of the battery case.

9. A battery case in which an iron-nickel diffusion layer is formed as a lower layer, a nickel layer is formed as an intermediate layer, and a bismuth layer is formed as an upper layer on the inner surface of the battery case.

10. The battery case according to claim 8, wherein the nickel layer comprises a matte nickel plating layer, a semi-bright nickel plating layer, or a bright nickel plating layer.

I I. A battery using the battery case according to claim 6.