WO2001042537A1

WO2001042537A1 - Surface treated steel sheet for battery case, battery case using it, and battery using the case

Info

Publication number: WO2001042537A1
Application number: PCT/JP2000/008713
Authority: WO
Inventors: Hitoshi Ohmura; Tatsuo Tomomori; Hideo Ohmura
Original assignee: Toyo Kohan Co., Ltd.
Priority date: 1999-12-09
Filing date: 2000-12-08
Publication date: 2001-06-14
Also published as: AU1735201A

Abstract

A surface treated steel sheet for a battery case, being excellent in surface appearance and capable of maintaining a discharge level for an extended time, a battery case and a battery using the battery case. The surface treated steel sheet for a battery case is characterized by having a bismuth layer or nickel-bismuth layer on a steel sheet. The battery case is produced by a drawing method, DI forming method and DTR forming method using the surface treated steel sheet. The battery is characterized by using this battery case.

Description

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

The present invention relates to a surface-treated steel sheet for a battery case, particularly to a surface-treated steel sheet used for a case of a primary battery such as an alkaline manganese 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 battery case, a method of press-forming a nickel-plated steel sheet or press-forming a cold-rolled steel sheet and then attaching nickel, which easily adheres to the steel sheet surface, is often used. Was.

After that, in order to further improve the battery performance, the adhesion between the inner surface of the case and the positive electrode mixture was

I In order to increase the surface area of the inner surface of the case at the same time as improving it, various methods have been proposed to reduce the internal resistance by forming a plating layer of nickel-lurin alloy or nickel-tin alloy, etc. .

However, although the nickel-tin alloy layer is excellent in reducing the internal resistance, when the nickel-iron alloy or the nickel-tin alloy is formed by the heat treatment using the box-type annealing method, the steel sheets adhere to each other. There was a problem. Disclosure of the invention

According to the present invention, since the bismuth metal has excellent alkali resistance, even if the bismuth metal is in contact with the alkaline solution for a long time, the plating layer components can be eluted into the alkaline solution. The focus was on the lack of such a material and the fact that bismuth metal oxide suppresses the diffusion of the underlying tin into the surface layer.

The present invention intends to provide a battery 5: whose discharge characteristics are not deteriorated for a long time by using such a property of bismuth metal and using a metal containing bismuth on the inner surface of the battery case. Furthermore, it is intended to provide a surface-treated steel sheet having no uneven appearance.

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

The surface treated steel sheet for a battery case according to the present invention is characterized in that a nickel | 0-bismuth alloy layer is formed on at least one outermost layer.

In these cases, it is desirable that the bismuth layer or the nickel-bismuth alloy layer is formed by electroplating.

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 at least one surface. 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, a tin layer is formed as an intermediate layer, and a bismuth layer is formed as an upper layer on at least one surface.

The surface-treated steel sheet for a battery case according to the present invention is characterized in that at least one surface has an iron-nickel diffusion layer formed as a lower layer, a nickel layer formed as an intermediate layer, and a bismuth 0 layer formed as an upper layer. I do.

These nickel layers are preferably a matte nickel plating layer, a semi-bright nickel plating layer, or a bright nickel plating layer.

The battery case of the present invention is characterized in that a bismuth layer is formed on at least one outermost layer of the battery case. In this case, it is desirable that the bismuth layer is formed by electroplating.

The battery case of the present invention has a nickel layer on at least one outermost layer of the battery case. A bismuth alloy layer is formed. In this case, it is desirable that the nickel-bismuth alloy layer is formed by electrolytic plating.

The 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 at least one surface of the battery case. The battery case of the present invention is characterized in that a nickel layer is formed as a lower layer, a tin layer is formed as an intermediate layer, and a bismuth layer is formed as an upper layer on at least one surface of the battery case.

The battery case of the present invention has a structure in which a 12-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 on a surface inside the battery case. Features. In this case, it is desirable that the nickel layer is a matte nickel plating layer, a semi-bright nickel plating layer, or a bright nickel plating layer.

The battery of the present invention is characterized by using the above battery case. BEST MODE FOR CARRYING OUT THE INVENTION

Since the bismuth layer is on the tin layer, it is possible to prevent the sheets from sticking to each other during the heat treatment by the box-type annealing method or to prevent tin from adhering to the opposing surface, so that the appearance of the surface-treated steel sheet is not uneven, It is possible to provide batteries with excellent quality and performance. Hereinafter, the present invention will be described in detail.

(1) Steel plate

When manufacturing the surface-treated steel sheet of the present invention, first, a mild steel sheet serving as a substrate is prepared. Preferred materials for the mild steel sheet include cold-rolled low-carbon A1 killed steel, ultra-low carbon steel with a carbon content of 0.003% or less, and non-aging ultra-low carbon steel to which niobium, boron, and titanium are added. used. The reason for using these mild steel sheets is to facilitate the ironing process for manufacturing cans in the subsequent processing operation. The thickness of the mild steel sheet used is preferably about 0.1 O mm to 0.40 mm. Subsequent DI processing Method. This is to facilitate the can forming process by the DTR processing method.

(2) Surface treatment

① Nickel plating

As the nickel plating method, any of the conventionally known methods of electroless plating and electrolytic plating can be used. Known plating baths, sulfamic acid baths, borofluoride baths, and the like can be used as plating baths when electrolytic plating is used, and any plating bath can be used. Further, the type of nickel plating deposited on the substrate may be any of non-luminous, semi-glossy, and glossy plating. The thickness of the nickel plating is preferably about 1 to 10 m.

0 ② Tin plating

As a method for tin plating, a known electrolytic plating method can be applied. The plating bath in this case includes a well-known ferrostan bath, a sulfuric acid bath, a chloride bath and the like, and any plating bath can be used. The thickness of the tin plating is preferably about 0.1 to 10 m.

| 5 "③ bismuth plating

As a bismuth plating method, any known plating bath such as a perchloric acid bath, a pyrophosphoric acid bath, a citric acid bath, a maleic sulfonic acid bath, and a chloride bath can be applied. In each of these baths, the basic composition is compatible with achieving the objectives of the present invention. In general, immersion baths containing organic substances often require strict bath management, and are liable to be expensive.However, such coating baths have a very thin plating layer like the surface-treated steel sheet of the present invention. As long as the above drawbacks are not so problematic.

However, when using a chloride bath, the composition of bismuth chloride: 80 to 120 g / L, sodium chloride: 15 to 20 g ZL, hydrochloric acid: approx. Although simple, it is necessary to provide an S polarity cycle, such as using the cathode for 10.5 seconds and then using the anode for 5 seconds. Also, if the substrate is already nickel strike plated, when the body is immersed in a chloride bath, This requires a complicated process in which the plating must be immersed in the bath during the anodic cycle because the plating will be dissolved.

If a metasulfonic acid bath is used, the basic bath composition is prepared by dissolving bismuth oxide in metasulfonic acid so that the final concentration of Bi ^{3 +} is 20 g ZL and the free acid concentration is 2 N. And a selective use of dispersants and brighteners.

As the dispersant, for example, it is preferable to use polyethylene glycol nonylphenyl ether. It is preferable to use a 20% solution of an amine aldehyde as a brightener. The reason for using a brightener is that the plating surface becomes powdery if no brightener is present. This is because the addition of the brightener tends to shift the cathode potential to the hydrogen generation potential, and has the effect of making the crystal structure of the plated surface finer and more beautiful.

In order to obtain the above-mentioned optimum effect, the blending composition of the brightener must be 1 to 1.5 parts by volume with respect to 1 part by weight of the dispersant. However, such an effect is hardly obtained.

The bath is preferably used at a temperature of 20 to 25 ° C. and a current density of 2 to 5 AZ dm ² .

Bismuth plated volume, when using this plated bath is usually, 0. 5 g Zm ² is preferred if more, because bismuth expensive, 0. 5~1. O g Zm 2 ranging der lever good. Also, the thickness of the plating layer can be adjusted by the plating time.

The formation of a bismuth plating layer on a steel sheet is performed by plating nickel on both sides of the steel sheet or tin plating after nickel plating, and then plating the bismuth on one or both sides.

つき Nickel-bismuth alloy plating

"Instead of the above-mentioned bismuth plating, nickel-bismuth alloy plating may be performed. As a plating bath, a sulfuric acid bath can be used. For example, nickel sulfate, bismuth sulfate, E A material containing DTA_2Na may be used. Usually, the plating amount is preferably 0.5 gZm ² or more as bismuth, but since bismuth is expensive, it may be in the range of 0.5 to 1.0 gZm ² .

The nickel-bismuth layer of the steel sheet is formed by nickel plating on both sides of the steel sheet, or nickel plating and tin plating, and then nickel-bismuth alloy plating on one or both sides.

(3) Diffusion layer formation

After performing the bismuth plating or the nickel-bismuth alloy plating, a diffusion treatment by a heat treatment is performed to form a nickel-iron alloy layer or a nickel-tin alloy layer.

The heat treatment is preferably performed under a non-oxidizing or reducing protective gas from the viewpoint of preventing formation of an oxide film on the surface of the alloy layer. As the non-oxidizing gas, a so-called inert gas such as nitrogen, argon, or neon is used. On the other hand, as the reducing gas, hydrogen, ammonia gas, or the like is suitably used.

As the heat treatment method, there are a box-type annealing method and a continuous annealing method, and any of these methods may be used. The heat treatment temperature is preferably in the range of 450 to 600 ° C, and the treatment time is preferably about 30 seconds to 10 hours. However, heat treatment conditions are also affected by the type of steel sheet. For example, when a very low carbon steel having a carbon content of 0.003 wt% or less is used as a substrate, the temperature is preferably set to a high temperature for a short time because the recrystallization temperature of the steel base is high.

(4) Battery case formation

For the battery case of the present invention, it is preferable to use a drawing method, a D I (d r aw i n g a d n i r o n i n g m molding method, a DTR (.d r aw i n g t h i n a n d r e d r aw) molding method, but other molding methods can also be used.

In the case of the DI forming method, first, a thin-walled surface-treated steel sheet whose diameter is slightly larger than the outer diameter of the battery case and which has a shallow drawing force is prepared by press forming. This cup is supplied to a plurality of ironing dies arranged coaxially in multiple stages so that the ironing aperture diameter is gradually reduced, and is pressed by a punch with a rounded tip to prevent necking. Through it continuously.

In the case of the DTR molding method, a shallow drawing force is prepared as in the case of the DI molding method described above.

^ Then, this cup is redrawn and then formed into a redrawn cup that is smaller in diameter and higher in height than the first shallow drawn cup. In other words, in the redrawing method, the nip is held by a ring-shaped holding member inserted into the cup and a redrawing die below the holding member, and the redrawing punch is held coaxially with the die in the holding member. It is arranged so as to be able to reciprocate, and a force of successively smaller diameter is used by using a redrawing punch of different diameter.

It is molded into an IC cup and finally a battery case.

(5) Dry battery fabrication

A dry battery is manufactured using the battery case. As an example, an alkaline manganese dry cell was manufactured. As the positive electrode mixture used for the alkaline manganese dry battery, a mixture of manganese dioxide, carbon powder, and an aqueous solution of Arikari is used.

5 Of these, manganese dioxide is a source of oxidizing components, so it is preferable to use one with high activity and high purity. Therefore, it is preferable that M N_〇 ₂ uses 9 1% or more electrolytic dioxide manganese.

In addition, it is desirable that the carbon powder has high purity and is chemically stable, and has good conductivity, mixability, and liquid retention. Examples of carbon powder satisfying these requirements include acetylene black, various types of modified carbon black, graphitized carbon black, and synthetic graphite powder.

The above-mentioned manganese dioxide and carbon powder are mixed in a weight ratio of 5: 1 to 10: 1, and an aqueous solution of hydroxylating water, which is an aqueous solution of water, is added thereto. By a suitable method to obtain a positive electrode mixture.

On the other hand, in order to improve the conductivity between the battery case and the positive electrode mixture, a mixture of graphite powder, a thermosetting resin, and an organic solvent such as methyl ethyl ketone is applied to the inner surface of the battery case. It is preferable to apply in advance by means of play or the like and dry it. Next, the positive electrode mixture prepared by kneading is press-formed using a mold to form a donut-shaped pellet, which is pressed into the battery case.

Further, the negative electrode plate having the negative electrode current collector rod spot-welded is mounted on the battery case, and a predetermined position below the opening end of the battery case is neck-in processed to fix the negative electrode plate.

The separator installed in the battery prevents the negative electrode active material and the product and the particles of the positive electrode active material from reciprocally moving, and prevents the negative electrode product from being generated in the separator to prevent internal short-circuiting and self-discharge of the battery. It is intended to prevent the occurrence, and a fibrous or non-woven fabric having alkali resistance is used. Examples of the material used for the separator include synthetic resin products such as 10-vinylon, polyolefin, and polyamide, linter pulp containing at least 98% of α-cellulose, mercerized wood pulp, and recycled cell mouth. Is done.

Insert these fibrous separators along the inner periphery of the positive electrode mixture pellet pressed into the battery case, and insert the negative electrode gel consisting of zinc oxide and zinc oxide-saturated hydroxide rim into the battery case. . Atomized powder having a center diameter of about 200 m is preferable as the sub-hulls used in this case, and starch, cellulose derivative, polyacrylate, etc. can be used as the gel material. Thereafter, an insulator gasket is further attached to the negative electrode body, inserted into a battery case, and caulked to obtain an alkaline manganese dry battery. Hereinafter, the present invention will be described in more detail with reference to Examples.

(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 : 0.01 wt%, S: 0.06 wt%, Al: 0.035 wt%, N: 0.0024 wt%. The steel sheet was immersed in an aqueous solution of N a OH a 30 gZ L dissolved 70 ° C, and treated 1 0 seconds at a current density of 5AZdm ² And alkaline electrolytic degreasing. After alkaline degreasing, the steel plate was immersed in a sulfuric acid aqueous solution (concentration: 50 g ZL) for 15 seconds to neutralize it by pickling, and then the steel sheet was air-agitated using a nickel pellet fitted with a polypropylene bag as the anode and under the following conditions. To give a matte nickel plating. Examples 1 and 2 show examples of matte nickel plating on both surfaces.

Examples 3 and 4 show examples in which saccharin was added as a brightening agent to the following matte nickel plating bath, and both sides were subjected to bright nickel plating.

Further, an example in which an unsaturated carboxylic acid formaldehyde, a polyoxyethylene adduct, a nitrogen-containing heterocyclic compound, or a nitrogen-containing aliphatic compound was added as a semi-brightening agent and both surfaces were subjected to semi-bright nickel plating was described in Example 5. And shown in 6.

Nickel plating condition

Bath composition Nickel sulfate: 300 gZL

Nickel chloride: 45gZL

Boric acid: 45gZL

Pitless agent: 0.5 g / L

Bath temperature 58 ± 2 ° C

P H 4.0 ± 0.2

Current density 25ΑΖ (ΐ Γη ²

After nickel plating, tin plating was applied to both sides under the following plating conditions.

Tin plating conditions

Bath composition Tin sulfate: 80 g / L

Phenolsulfonic acid: S OgZL

Salt ： 5gZL

Bath temperature 45 ± 2 ° C

Current density 5AZdm ²

Next, for Examples 1 to 3, the bismuth plating was performed on one side using the following bismuth chloride bath. It was applied to.

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

Bath temperature 22 ± 2 ° C

p H 0.7

Current density SAZdm ²

o In Examples 4 to 6, instead of bismuth plating, nickel-bismuth plating was applied to one surface in the following sulfuric acid bath.

Nickel-bismuth plating conditions

Bath composition Nickel sulfate 240 g / L

Bismuth sulfate 1.4 g / L

5 EDTA- 2Na 20 g / L

Sulfuric acid (pH adjustment)

Bath temperature 40 ± 2 ° C

pH 1.5

Current density 1 0 AZdm ²

After plating with ZD bismuth or nickel-bismuth, use a box-type annealing furnace.

Heat treatment was performed at a temperature in the range of 0 to 600 ° C. to modify the nickel-tin alloy layer. In this case, the atmosphere gas was hydrogen: 6%, the balance was nitrogen gas, and the dew point temperature was set to 145 ° C. Table 1 summarizes the nickel plating thickness, tin plating thickness, bismuth plating thickness, nickel-bismuth plating thickness, and heat treatment conditions.

A battery case was fabricated by DI molding using the plated steel sheet. The above heat-treated steel sheet with a thickness of 0.25 mm is converted from a blank diameter of 4 mm to a diameter of 20.5 mm. into a cup with a diameter of 13.8 mm, a side wall thickness of 0.20 mm, and a height of 56 mm. Molded. The upper part of the case was trimmed to make a 49.3 mm high LR-6 battery case. Then, the battery case was filled with the positive electrode active material, and a battery was prepared as described below, and the battery performance was measured.

First, manganese dioxide and graphite powder were collected at a weight ratio of 10: 1, and mixed with 8 mol of hydroxide hydroxide to prepare a positive electrode mixture.

On the other hand, a liquid obtained by diluting a mixture of graphite powder (80 parts by weight) and thermosetting epoxy resin (20 parts by weight) with methyl ketone is sprayed on the inner surface of the battery case and heated at 150 ° C. for 0.15 minutes. Dried. The positive electrode mixture prepared above was press-molded in a mold to form a donut-shaped pellet and pressed into the battery case.

In addition, in order to mount the negative electrode plate with the negative electrode current collector rod spot welded to the battery case, a predetermined position under the opening end of the battery case was neck-in processed.

Next, a separator made of vinylon non-woven fabric is inserted along the inner periphery of the pellets pressed into the battery case, and the negative electrode gel made of a hydroxide rim saturated with zinc particles and zinc oxide is used as the battery case. Inserted in. Furthermore, an insulator gasket was attached to the negative electrode body, inserted into the battery case, and caulked to produce a finished alkaline manganese dry battery. Table 2 shows the results of measuring the internal resistance, short-circuit current value, and 2 Ω continuous discharge time Z0 (min) of the thus-produced alkaline manganese dry battery after leaving it at 60 ° C for 20 days.

(Examples 7 to 9)

Matte nickel plating was performed in the same manner as in Example 1, except that a steel plate 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. After the nickel plating, the above-mentioned bismuth or nickel-bismuth plating is performed, and a heat treatment is performed in the range of 450 to 600 ° C using a box-type annealing furnace to obtain a nickel-iron alloy. The layers were denatured. The atmosphere gas in this case is hydrogen: 6%, The remainder was nitrogen gas and the dew point temperature was set at 145 ° C.

Table 1 summarizes the nickel plating thickness, nickel-bismuth plating thickness, bismuth plating thickness, and heat treatment conditions. In addition, Table 2 summarizes the battery characteristics measured for Al-manganese dry batteries manufactured in the same manner as in Example 1 using this surface-treated steel sheet.

(Comparative Examples 1-2)

In Comparative Example 1, nickel plating, tin plating, and further heat treatment were performed under the same conditions as in Example 1 by using a steel plate having the same quality and the same thickness as in Example 1. However, no bismuth plating was carried out. In Comparative Example 2, tin plating in Comparative Example 1 was not performed. Table 1 summarizes the steel sheet properties. Table 2 summarizes the battery characteristics when fabricated using this steel sheet.

Table 1 Thickness of plating layer and heat treatment conditions

Table 2 Characteristics evaluation results Example or tin transfer-off adhesion Discharge time Comparative example (min) Example ¾i Example 1 〇〇 1 0 5 Example 2 〇〇 1 1 0 Example 3 〇〇 1 1 2 Example 4 (! 1 1 8 夹 Ml o

丄 4 Example 6 〇〇 1 0 2 Example 7 〇〇 1 1 5 Example 8 〇〇 1 2 1 Example 9 〇〇 1 2 3 Comparative Example 1 XX 1 0 5 Comparative Example 2 XX 1 0 5 The characteristics of the steel sheet and the battery characteristics in Examples and Comparative Examples were measured as follows.

(1) Tin set-off

In the examples, a test was conducted to confirm whether or not tin had set off during the heat treatment after the bismuth plating or the nickel-bismuth plating. In this test, 10 sheets of bismuth-plated or nickel-bismuth-plated surfaces and surfaces not subjected to bismuth-plated or nickel-bismuth-plated were superposed. The heat treatment in the comparative example was also performed by stacking 10 samples. The heat treatment was performed so that a pressure of 1 kg / cm ² was applied to the sample. In order to confirm whether or not tin had set off on the surface that was not subjected to bismuth plating or nickel-bismuth plating, the amount of tin on the sample surface was measured with fluorescent X-rays to detect tin. When detection of tin is recognized

(Tin set-off) is indicated by x, and no detection (no tin set-off) is indicated by 〇.

(2) Adhesion of plate

In the examples, a test was conducted to confirm whether or not the plate adhered during the heat treatment after the bismuth plating or the nickel-bismuth plating. In this test, 10 sheets of bismuth-plated or nickel-bismuth-plated surfaces and surfaces not subjected to bismuth-plated or nickel-bismuth-plated were stacked face-to-face. The heat treatment in the comparative example was also performed by stacking 10 samples. The heat treatment was performed so that a pressure of 1 kg Z cm ² was applied to the sample. After the heat treatment, x indicates that the plates were in close contact with each other, and 〇 indicates that the plates were not in close contact.

(3) Continuous discharge time

A closed circuit was created by connecting a 2 Ω resistor to the battery, and the elapsed time until the voltage reached 0.9 V was measured. Industrial applicability As shown in Table 2, the surface treated steel sheet for a battery case of the present invention has a bismuth layer or a nickel-bismuth layer as the outermost layer. Is better.

In addition, a dry battery using the surface-treated steel sheet for a battery case of the present invention as a battery case has excellent effects in terms of discharge duration and the like.

Claims

The scope of the claims

I. A surface-treated steel sheet for a battery case in which a bismuth layer is formed on at least one outermost layer.

ξ 2. A surface-treated steel sheet for a battery case having a nickel-bismuth alloy layer formed on at least one outermost layer.

3. The surface-treated steel sheet for a battery case according to claim 1, wherein the bismuth layer is formed by electrolytic plating.

4. The nickel-bismuth alloy layer is formed by electrolytic plating. 3. The surface-treated steel sheet for a battery case according to claim 2, wherein:

5. A surface treated steel sheet for a battery case that has a nickel layer as a lower layer and a bismuth layer as an upper layer on at least one side.

6. A surface-treated steel sheet for a battery case having a nickel layer as a lower layer, a tin layer as an intermediate layer, and a bismuth layer as an upper layer on at least one surface.

7. A surface-treated steel sheet for a battery case in which an iron-nickel diffusion layer is formed as a lower layer on at least one side, a nickel layer is formed as an intermediate layer, and a bismuth layer is formed as an upper layer.

8. The surface-treated steel sheet for a battery case according to claim 5, wherein the nickel layer comprises a matte nickel plating layer, a semi-bright nickel plating layer 0, or a bright nickel plating layer.

9. A battery case with a bismuth layer formed on at least one outermost layer of the battery case.

10. A battery case in which a nickel-bismuth alloy layer is formed on at least one outermost layer of the battery case.

II. The bismuth layer is formed by electroplating. 10. The battery case according to claim 9, wherein:

12. The battery case according to claim 10, wherein the nickel-bismuth alloy layer is formed by electrolytic plating.

13. A nickel layer is formed as a lower layer on at least one side of the battery case.

Battery case in which bismuth layer is formed as 5 layers.

14. A battery case in which a nickel layer is formed as a lower layer, a tin layer is formed as an intermediate layer, and a bismuth layer is formed as an upper layer on at least one surface of the battery case.

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

16. The battery case according to claim 13, wherein the nickel layer comprises a matte nickel plating layer, a semi-bright nickel plating layer, or a bright nickel plating layer.

5 "17. A battery using the battery case according to any one of claims 9 to 16.