TW201813158A - Steel sheet for outer jacket can of battery, outer jacket can of battery and battery - Google Patents

Abstract

Provided are: a steel sheet for a battery outer cylindrical canister, the steel sheet being subjected to post-plating, able to suppress damage even if press molding is repeated using a mold made of quenched steel, and providing a battery outer cylindrical canister with good corrosion resistance; a battery outer cylindrical canister; and a battery using the battery outer cylindrical canister. The steel sheet for the battery outer cylindrical canister comprises Fe-Ni diffusion layers on surface layers on both sides of the steel sheet. The amount of deposition of the Fe-Ni diffusion layers in terms of Ni is 50-500 mg/m2 on each surface of the steel sheet.

Description

   Steel plate for battery outer can, battery outer can, and battery   

The present invention relates to a steel plate for a battery can, a battery can, and a battery.

As the battery, for example, a primary battery such as an alkaline manganese battery, a secondary battery such as a lithium ion battery mounted on a notebook computer, a hybrid car, or the like is known.

On the surface of the steel plate constituting the outer can (battery outer can) used in these batteries, from the viewpoint of corrosion resistance, Ni plating is performed to form a Ni layer.

There are two manufacturing methods for battery outer cans, depending on the steps of Ni plating.

One is the first plating method, in which a steel plate subjected to Ni plating is punched to form a battery outer can, and then no plating treatment is performed. The other method is a post-plating method, in which Ni is plated on the surface of a battery outer can after press forming by a method such as barrel plating.

As a steel sheet for battery outer cans used in the post-plating method, for example, Patent Document 1 discloses "a Ni-plated steel sheet for a container, characterized in that it has a thickness of 0.5 µm or more on the surface that becomes the inner surface of the container by press forming. An Fe-Ni diffusion layer having a thickness of 4 μm or less, further having a Ni layer having a thickness of 0.25 μm or more and 4 μm or less thereon, and an adhesion amount of 0.05 g / m ² or more and less than 1.5 g / m ² on the surface that becomes the outer surface of the container. Ni, the Ni is diffused inward, and the Ni / (Fe + Ni) mass ratio of the surface layer is 0.1 or more and 0.9 or less "(request item 1).

In Patent Document 1, after a steel sheet for a battery can (Ni-plated steel sheet for a container) is press-formed to form a battery can, a nickel plating is applied to the outside by a method such as drum plating.

[Patent Document 1] Japanese Patent No. 4995140

As a material of a forming mold (die) used for press forming by the post-plating method, a cemented carbide is mostly used, and a brittle hardened steel may be used in some cases.

When the press forming of the steel sheet for battery outer cans (Ni-plated steel sheet for containers) of Patent Document 1 is repeatedly performed using a forming mold made of hardened steel, the forming mold is gradually damaged, and as a result, the formed battery may be damaged. The steel sheet for cans was scratched. In this case, the obtained outer can of the battery may be damaged, and the corrosion resistance may be deteriorated.

Therefore, an object of the present invention is to provide a steel plate for battery outer cans, which is a steel plate for battery outer cans used in the post-plating method, and can prevent cracks even when press forming is performed repeatedly using a forming mold made of hardened steel. And the obtained outer battery can is excellent in corrosion resistance, and the outer battery can and battery using the steel plate for the outer battery can are provided.

As a result of intensive investigations by the present inventors, it has been found that the above-mentioned object can be achieved by using a steel sheet for a battery outer cylinder can having a specific Fe-Ni diffusion layer on the surface layer on both sides of the steel sheet, and completed the present invention.

That is, the present invention provides the following [1] to [8].

[1] A steel sheet for battery outer cans, the surface layers of which are on both sides of the steel sheet have Fe-Ni diffusion layers, and the Fe-Ni diffusion layer is converted into an Ni adhesion amount of 50 mg / m ² or more on each side of the steel sheet, 500mg / m ² or less.

[2] The steel sheet for battery outer cans according to the above [1], wherein the Ni ratio on the outermost surface of the Fe-Ni diffusion layer is 1.0% or more and less than 20.0%. The Ni ratio is a ratio of the Ni amount to the total amount of the Fe amount and the Ni amount on the outermost surface of the Fe-Ni diffusion layer, and the unit of the Fe amount and the Ni amount is atomic%.

[3] The steel sheet for a battery outer cylinder can according to the above [1] or [2], wherein the thickness of the Fe-Ni diffusion layer is 0.01 μm or more and less than 0.5 μm.

[4] A battery outer can, which has an Fe-Ni diffusion layer on the inner surface and the outer surface of the steel plate of the battery outer can shape, and further has a Ni layer on the Fe-Ni diffusion layer on the outer side of the steel plate. A part of the Fe-Ni diffusion layer on the outer surface side of the steel sheet is an Fe-Ni diffusion layer A converted to a Ni adhesion amount of 50 mg / m ² or more and 500 mg / m ² or less on each side of the steel sheet.

[5] The battery outer can according to the above [4], wherein the Ni ratio on the outermost surface of the Fe-Ni diffusion layer A is 1.0% or more and less than 20.0%. The Ni ratio is a ratio of the Ni amount to the total amount of the Fe amount and the Ni amount on the outermost surface of the Fe-Ni diffusion layer, and the unit of the Fe amount and the Ni amount is atomic%.

[6] The battery outer can according to the above [4] or [5], wherein the thickness of the Fe-Ni diffusion layer A is 0.01 μm or more and less than 0.5 μm.

[7] The battery outer can according to any one of the above [4] to [6], wherein the thickness of the Ni layer is 1 μm or more.

[8] A battery including the battery outer can as described in any one of the above [4] to [7], an electrolytic solution, an electrode, and a separator disposed inside the battery outer can.

According to the present invention, it is possible to provide a steel plate for battery outer cans, which is a steel plate for battery outer cans used in the post-plating method, and the occurrence of scratches can be suppressed even when press forming is performed repeatedly using a forming mold made of hardened steel. In addition, the obtained outer battery can is excellent in corrosion resistance, and a battery outer can and a battery using the steel plate for the outer battery can are provided.

    [Steel plate for battery outer cans]    

The steel sheet for battery cans of the present invention (hereinafter also simply referred to as "steel sheet for cans of the present invention") has a surface layer on both sides of the steel sheet having Fe-Ni diffusion layers, and the Fe-Ni diffusion layer is converted into the steel sheet. The Ni adhesion amount (hereinafter also referred to as "Ni adhesion amount") on each side is 50 mg / m ² or more and 500 mg / m ² or less.

The steel sheet for cans of the present invention is a steel sheet for battery outer cans used in the post-plating method, and even if the press forming is repeatedly performed using a forming die made of hardened steel, the occurrence of flaws can be suppressed, and the obtained battery outer can The tank has excellent corrosion resistance.

The reason can be presumed as follows.

First, the steel sheet for battery outer cans used in the post-plating method described in Patent Document 1 has an "Fe-Ni diffusion layer having a thickness of 0.5 µm or more ... on the surface which becomes the inner surface of the container by press forming". ". The conversion amount of Ni in the Fe-Ni diffusion layer was 4500 mg / m ² or more.

The steel sheet for battery outer cans of Patent Document 1 is hardened due to excessive Ni adhesion of the Fe-Ni diffusion layer, and a brittle hardened steel forming mold is gradually injured during press forming. In addition, since the wound mold was used, the formed steel sheet for battery cans could be damaged.

However, in the Fe-Ni diffusion layer of the steel sheet for cans of the present invention, the Ni adhesion amount is moderately reduced to 500 mg / m ² or less, and it is softened to the extent that it does not damage the forming mold made of hardened steel. Therefore, it is possible to suppress the occurrence of scratches (hereinafter also referred to as "excellent scratch resistance") of the formed steel sheet for battery cans. In addition, the steel sheet for cans of the present invention is excellent in scratch resistance, and also has excellent corrosion resistance in the obtained outer battery can.

When the amount of Ni adhered to the Fe-Ni diffusion layer of the steel sheet for cans of the present invention is too small, the corrosion resistance of the obtained outer can of the battery may be deteriorated. However, in the steel sheet for cans of the present invention, because the Ni adhesion amount of the Fe-Ni diffusion layer is moderately increased to 50 mg / m ² or more, the corrosion resistance (hereinafter also simply referred to as "corrosion resistance") when the battery outer can is made. good.

In more detail, when the outer can of a battery is made, the inner surface of the battery can improve the electrochemical stability of the Fe-Ni diffusion layer, which can be improved compared to the case where the Fe-Ni diffusion layer is not provided or is too small. Its corrosion resistance to the contents.

On the other hand, although a Ni layer is formed on the outside by Ni plating using drum plating or the like after forming, there are pinholes in the Ni layer, and corrosion progresses from there. However, the Fe-Ni diffusion layer is appropriately provided as the base layer of the Ni layer. Compared with the case where the Fe-Ni diffusion layer is not provided or is too small, the potential difference between the Ni layer and the base layer can be reduced, and the corrosion resistance can be reduced improve.

Hereinafter, each part provided in the steel plate for cans of this invention is demonstrated in detail.

    <Steel plate>    

The type of the steel plate is not particularly limited. A steel plate generally used as a battery container material (for example, a low-carbon steel plate or an extremely low-carbon steel plate) may be used. However, when Cr is contained in the steel sheet, the steel may be hardened to reduce formability, or Cr oxide may be formed on the surface of the steel sheet during annealing, and the desired surface state may not be obtained. Therefore, the Cr content of the steel sheet is preferably less than 3% by mass, and more preferably less than 1% by mass.

The manufacturing method of a steel plate is also not specifically limited. For example, it can manufacture from a normal steel sheet manufacturing process through the process of hot rolling, pickling, cold rolling, annealing, and temper rolling.

In the present invention, because the formation of a Fe-Ni diffusion layer is necessary, from the viewpoint of the best production efficiency, Ni plating is performed on the unannealed steel sheet after cold rolling, and Ni plating is diffused while the steel sheet is annealed. Into the steel plate. Therefore, as the steel sheet, an unannealed steel sheet after cold rolling is preferably used.

    <Fe-Ni diffusion layer>    

The steel sheet for cans of the present invention has a Fe-Ni diffusion layer on the surface layer on both sides of the steel sheet.

    《Ni adhesion amount》    

The Fe-Ni diffusion layer is converted into a Ni adhesion amount (Ni adhesion amount) on each side of the steel sheet of 50 mg / m ² or more and 500 mg / m ² or less. As described above, the steel sheet for cans according to the present invention is excellent in both scratch resistance and corrosion resistance as described above. For reasons of more excellent scratch resistance, the Ni adhesion amount of the Fe-Ni diffusion layer is preferably 350 mg / m ² or less, and more preferably 300 mg / m ² or less.

The amount of Ni deposited in the Fe-Ni diffusion layer can be measured by surface analysis using X-ray fluorescence analysis. In this case, a Ni adhesion sample having a known Ni adhesion amount is used, and a calibration curve related to the Ni adhesion amount is obtained in advance, and then the relative Ni adhesion amount is obtained using the calibration curve. X-ray fluorescence analysis is performed under the following conditions, for example.

‧Equipment: X-ray fluorescence analyzer System3270 made by Rigaku

‧Measurement diameter: 30mm

‧Measurement atmosphere: vacuum

‧Spectrum: Ni-Kα

‧Slit: COARSE

‧Spectral crystallization: TAP

The peak count of Ni-Kα in X-ray fluorescence analysis using the Fe-Ni diffusion layer measured under the above conditions. A standard sample whose adhesion amount is known after measuring the adhesion amount by a gravimetric method is used to obtain a calibration curve related to the Ni deposition amount in advance, and the relative Ni deposition amount is obtained using the calibration curve.

    "Thickness"    

In the steel sheet for cans of the present invention, the thickness of the Fe-Ni diffusion layer is preferably 0.01 μm or more because it is easy to maintain the Fe-Ni diffusion layer after forming and to further improve the scratch resistance and corrosion resistance. It is 0.5 μm, and for reasons of further improving scratch resistance, it is more preferably 0.4 μm or less, and particularly preferably 0.38 μm or less.

The thickness of the Fe-Ni diffusion layer can be measured by GDS (Glow Discharge Luminescence Analysis). Specifically, first, sputtering is performed from the surface of the Fe-Ni diffusion layer toward the inside of the steel sheet, and analysis in the depth direction is performed to obtain a sputtering time at which the intensity of Ni becomes a maximum of 1/10. Next, the relationship between the sputtering depth and the sputtering time was determined by GDS using pure iron. Using this relationship, the sputtering depth was calculated from the sputtering time at which 1 / 10th of the Ni intensity reached the maximum value was converted into pure iron, and the calculated value was used as the thickness of the Fe-Ni diffusion layer. GDS is implemented under the following conditions.

‧Equipment: GDA750 by Rigaku Corporation

‧Anode inner diameter: 4mm

‧Analysis mode: high frequency and low voltage mode

‧Discharge power: 40W

‧Control pressure: 2.9hPa

‧Detector: Photomultiplier tube

‧ Detection wavelength: Ni = 341.4nm

    《Ni ratio》    

In the steel sheet for a can of the present invention, the Ni ratio on the outermost surface of the Fe-Ni diffusion layer (hereinafter also simply referred to as the "Ni ratio") is preferably 1.0% or more because of its superior scratch resistance and corrosion resistance. Less than 20.0%.

The reason why the Ni ratio of the outermost surface of the Fe-Ni diffusion layer is important is that although the outermost Ni of the Fe-Ni diffusion layer has a direct effect on the corrosion resistance, the effect of improving the corrosion resistance of Ni after diffusion into the steel is small. . On the other hand, when the Ni ratio is too high, the outermost surface becomes hard, and the scratch resistance may become insufficient. Therefore, an appropriate range of the Ni ratio is 1.0% or more and less than 20.0%.

For the reason that the scratch resistance is more excellent, the lower limit of the Ni ratio is more preferably 3.0%. For the same reason, the upper limit of the Ni ratio is more preferably 15.0%, and particularly preferably 13.0%.

The Ni ratio (unit:%) on the outermost surface of the Fe-Ni diffusion layer is the ratio of the amount of Ni to the total amount of Fe and Ni in the outermost surface of the Fe-Ni diffusion layer. “Ni amount / (Fe amount + Ni amount) × 100” is calculated. The unit of the amount of Fe and Ni is atomic%.

The amount of Fe (unit: atomic%) and Ni (unit: atomic%) on the outermost surface of the Fe-Ni diffusion layer can be ultrasonically cleaned in acetone for 10 minutes after forming the Fe-Ni diffusion layer. After that, no sputtering was performed, and the measurement was performed by performing an Auger electron spectrum measurement. Oujie Electronic Spectroscopy is performed at 10 places using different fields of view in the same sample. The Fe and Ni amounts are the average of the results at 10 places. Auje electron spectrometry was performed under the following conditions.

‧Installation: PHI660 made by ULVAC-PHI

‧Observation and analysis conditions: acceleration voltage 10.0kV, current value 0.5μA

Observation magnification 1,000 times, measurement range 540 ~ 900eV

    "Formation method of Fe-Ni diffusion layer"    

The method for forming the Fe-Ni diffusion layer on the surface layer on both surfaces of the steel sheet is not particularly limited, and the following method is mentioned as an example.

First, the non-annealed steel sheet after cold rolling is subjected to pre-treatment (degreasing, pickling, etc.) as necessary, and then subjected to Ni plating using a Ni plating bath and appropriately adjusting conditions such as current density. Examples of the Ni plating bath include a Watt bath, a sulfamic acid bath, a fluoroboride bath, and a chloride bath.

At this time, the adhesion amount of Ni plating is 50 mg / m ² or more and 500 mg / m ² or less on each side of the steel sheet. In this way, the Ni adhesion amount of the formed Fe-Ni diffusion layer can be 50 mg / m ² or more and 500 mg / m ² or less.

Next, the steel sheet subjected to Ni plating is annealed (preferably continuous annealing) for the purpose of recrystallization treatment of the steel sheet. In this way, as the steel sheet is annealed, Ni plating is diffused into the steel sheet to form a Fe-Ni diffusion layer.

As the annealing conditions, the soaking temperature is preferably 600 ° C. or more and 800 ° C. or less, and the holding time at the soaking temperature is preferably 10 seconds or more and 60 seconds or less. The shorter the holding time at the soaking temperature, the more difficult it is for Ni to diffuse into the steel, and the ratio of Ni at the outermost surface becomes larger. From the viewpoint of corrosion resistance, the holding time at the soaking temperature is more preferably less than 30. second.

When this annealing condition is adopted, the thickness of the formed Fe-Ni diffusion layer can be 0.01 μm or more and less than 0.5 μm, and the ratio of Ni on the outermost surface can be 1.0% or more and less than 20.0%. Good.

After forming the Fe-Ni diffusion layer, if necessary, shape correction, surface roughness adjustment, and the like are performed by temper rolling.

    [Manufacturing method of battery outer cans]    

Next, a method for manufacturing a battery outer cylinder can using the steel sheet for cans of the present invention (hereinafter, also referred to as "the manufacturing method of the present invention" for convenience) will be described.

The manufacturing method of the present invention includes, for example, a step of forming the steel sheet for a can of the present invention into a battery outer can shape (for example, a cylindrical shape) by press forming using a forming die, and then forming the The step of forming the Ni layer on the outer surface of the steel sheet for cans of the present invention after the shape of the battery outer can is performed.

    <Forming (press forming)>    

The method of forming (press forming) is not particularly limited, and can be performed by a general method used for forming a battery outer can. For example, the steel sheet for cans of the present invention is die-cut into a circle, and is formed into a shape such as a cylindrical shape by the steps of drawing into a cup shape, redrawing, and DI (drawing and ironing).

At this time, although the material of the forming mold used is mostly a cemented carbide, a brittle hardened steel can also be used. As described above, it is conceivable that the Fe-Ni diffusion layer of the steel sheet for cans of the present invention does not damage the forming mold made of hardened steel, and therefore, it is possible to suppress the occurrence of scratches on the formed steel sheet for battery cans for outer cans.

The Ni adhesion amount, thickness, and Ni ratio of the Fe-Ni diffusion layer after the press forming cannot be maintained and the state before the press forming is changed.

However, in the steel sheet for cans of the present invention, at least a part of the portion that becomes the outer side of the battery outer can (for example, the portion that becomes the end surface of the protrusion on the positive side of the battery outer can) is not maintained by press forming. No processing status.

Therefore, at least a part of the outer surface side of the battery outer can (the battery outer can of the present invention) obtained by using the can steel sheet of the present invention is Fe-Ni of the steel sheet for cans of the present invention before the press forming is maintained. Ni adhesion amount, thickness and Ni ratio of the diffusion layer.

    <Ni-plating after forming into the shape of a battery outer can>    

The method for performing Ni plating is not particularly limited, and a conventionally known method can be adopted. For example, the steel sheet for cans of the present invention after being formed into the shape of a battery outer can, a Ni plating bath is used, and conditions such as current density are appropriately adjusted, and Ni plating is performed by a drum plating method. Examples of the Ni plating bath include a Watt bath, a sulfamic acid bath, a fluoroboride bath, and a chloride bath.

Thereby, Ni-plating is performed on the Fe-Ni diffusion layer on at least the outer surface side of the steel sheet for cans of the present invention after being formed into the shape of a battery outer cylinder can, to form a Ni layer.

At this time, since the steel sheet for cans of the present invention is formed into the shape of a battery outer can, the Ni plating does not easily penetrate into the inside. Therefore, it is difficult to perform Ni plating on the inner surface of the steel sheet for cans of the present invention. Of course, the inner surface of the steel sheet for cans according to the present invention in the shape of a battery outer cylinder can also be Ni-plated to form a Ni layer in the same manner as the outer surface.

From the viewpoint of corrosion resistance, the thickness of the Ni (Ni layer) plating formed on the Fe-Ni diffusion layer is preferably 1 μm or more, and more preferably 2 μm or more. The upper limit of the thickness of the Ni layer is not particularly limited, and it is preferably 7 μm or less from the viewpoint of economy, for example.

    [Battery canister]    

The outer battery can of the present invention is a battery outer can obtained by using the can steel sheet of the present invention.

More specifically, the outer battery can of the present invention has an Fe-Ni diffusion layer on the inner surface and the outer surface of the steel plate in the shape of the outer battery can, and the Fe-Ni diffusion layer is on the outer side of the steel plate. It further has a Ni layer, and a part of the Fe-Ni diffusion layer on the outer side of the steel sheet is an Fe-Ni diffusion layer A converted to a Ni adhesion amount of 50 mg / m ² or more and 500 mg / m ² or less on each side of the steel sheet. .

The outer battery can of the present invention is firstly formed into a battery outer can shape by press forming, and Fe-Ni is formed on the surface layers of both sides (inner surface and outer surface) of the steel plate similarly to the can steel of the present invention. Diffusion layer. Next, Ni is plated on the Fe-Ni diffusion layer on at least the outer surface side of the steel sheet to form a Ni layer.

Here, as described above, at least a part of the Fe-Ni diffusion layer on the outer side of the battery can of the present invention is the Fe-Ni diffusion layer (Ni adhesion amount) of the steel sheet for cans of the present invention before the press forming is maintained. : 50 mg / m ² or more and 500 mg / m ² or less).

That is, in the outer battery can of the present invention, at least a part of the Fe-Ni diffusion layer on the outer side of the steel plate in the shape of the outer battery can has a Ni adhesion amount of 50 mg / m ² or more and 500 mg / m ² or less. Fe-Ni diffusion layer A.

The appropriate ranges of the Ni adhesion amount, thickness, and Ni ratio of the Fe-Ni diffusion layer A in the outer can of the battery of the present invention are the Ni adhesion amount, thickness, and Ni adhesion of the Fe-Ni diffusion layer on the can steel sheet of the present invention. The Ni ratio is the same.

In the outer battery can of the present invention, the thickness of the Ni layer on the Fe-Ni diffusion layer is as described above, preferably 1 μm or more, and more preferably 2 μm or more. The upper limit is not particularly limited, but is preferably 7 μm or less.

    [Battery]    

The battery of the present invention includes the battery outer can of the present invention, an electrolytic solution, an electrode, and a separator disposed inside the battery outer can of the present invention.

That is, the battery of the present invention is filled with at least the structure necessary for the battery, that is, the electrolyte, the electrode, and the separator, and other structures may be further filled as necessary.

Since the battery of the present invention uses the battery outer can of the present invention, it has excellent corrosion resistance.

    [Example]    

Hereinafter, the present invention will be specifically described with examples. However, the present invention is not limited to these examples.

    <Manufacture of steel plate for battery outer cans>    

As the steel sheet, a non-annealed Nb-added ultra-low carbon steel having a thickness of 0.25 mm after cold rolling (steel composition, including C: 0.002%, Si: 0.02%, Mn: 0.15%, P in mass%) : 0.01%, S: 0.008%, Ni: 0.02%, Nb: 0.01%). This steel plate is processed before including degreasing and pickling.

The steel sheet after the pretreatment was subjected to Ni plating using a Watt bath. At this time, conditions such as the current density are appropriately adjusted so as to be the Ni adhesion amount (unit: mg / m ² ) set forth in Table 1 below.

Next, the steel sheet subjected to Ni plating is introduced into a continuous annealing line, the steel sheet is annealed, and Ni is diffused into the interior of the steel sheet to form Fe-Ni diffusion layers on the surface layers on both surfaces of the steel sheet. At this time, the thickness (unit: μm) and Ni ratio (unit:%) of the Fe-Ni diffusion layer are set to the following table 1 by using the annealing conditions (soaking temperature and holding time) set forth in the following table 1. Loaded value.

After the Fe-Ni diffusion layer was formed, quenched and tempered rolling was performed to obtain steel sheets for battery outer cans of test materials Nos. 1 to 27.

    <Manufacture of battery cans>         "Shaping"    

The obtained battery outer cylinder can was punched into a circular shape, and formed into a cylindrical shape of an 18650-type battery outer cylinder can by being stretched into a cup shape, re-extension, and DI steps. The thickness of the side wall portion is reduced to 0.15 mm by the DI step.

    "Ni plating"    

Then, at least the outer surface of the steel sheet for battery outer cans formed into the shape of the battery outer cans was subjected to Ni plating by a drum plating method to form a Ni layer having a thickness of 4 μm. Thus, a battery outer can was obtained.

    <Evaluation>         "Corrosion resistance"    

An aqueous solution prepared by mixing 5 g of sodium chloride and 1.5 cc of a 30% hydrogen peroxide aqueous solution with 100 g of pure water was prepared. The obtained outer battery can was immersed in the aqueous solution at room temperature for 16 hours. After immersion, the battery can was pulled out, and the presence or absence of holes was evaluated visually. When it was confirmed that there was a hole, it was evaluated as "B". . "A" indicates excellent corrosion resistance.

    "Durability"    

The above-mentioned forming was repeated using a forming die made of hardened steel, and the number of times (the number of cans) until the flaw was visually confirmed on the surface of the steel sheet for a battery outer can after being formed into the shape of the battery outer can was counted.

When the number of cans made until the flaw was confirmed was 50,000 cans or less, it was evaluated as "D", and when the number of cans was over 50,000 to 70,000 cans, it was evaluated as "C". The number of cans was over 70,000 to 100,000 cans The case evaluation was "B", and even if the number of cans made exceeded 100,000 cans, the case where no flaw was recognized was evaluated as "A", and it is described in Table 1 below.

"A", "B", or "C" indicates excellent damage resistance. Practically, "A" or "B" is better, and "A" is better.

As shown in Table 1 above, the test materials Nos. 10 to 11 and 22 to 23 of which the Ni adhesion amount of the Fe-Ni diffusion layer exceeded 500 mg / m ^{2 had} poor scratch resistance. The test materials Nos. 12 and 24 of which the Fe-Ni diffusion layer had an Ni adhesion amount of less than 50 mg / m ^{2 had} poor corrosion resistance.

In contrast, the test materials Nos. 1 to 9, 13 to 21, and 25 to 27 of the Fe-Ni diffusion layer with a Ni adhesion amount of 50 mg / m ² or more and 500 mg / m ² or less showed good scratch resistance and scratch resistance. .

The test materials No. 1 to 9, 13 to 21, and 25 to 27 were compared, and the ratio of Ni on the outermost surface of the Fe-Ni diffusion layer was 1.0% or more and less than 20.0%. 13 to 21 and 26 to 27, the damage resistance is better than the test material No. 25 with a Ni ratio of 20.0% or more.

The test materials Nos. 1 to 9 were compared, and the test materials Nos. 1 to 4 and 8 to 9 with lower Ni ratios were better than the test materials Nos. 5 to 7.

Similarly, comparing test materials Nos. 13 to 21, compared with test materials Nos. 17 to 19, test materials Nos. 13 to 16 and 20 to 21 with lower Ni ratios have better scratch resistance.

Claims (8)

A steel sheet for a battery outer cylinder can has a Fe-Ni diffusion layer on a surface layer on both sides of the steel sheet, and the foregoing Fe-Ni diffusion layer is a conversion of an Ni adhesion amount of 50 mg / m ^{2 to} 500 mg / m on each side of the steel sheet. ² or less.     The steel sheet for battery outer cans according to claim 1, wherein the Ni ratio on the outermost surface of the Fe-Ni diffusion layer is 1.0% or more and less than 20.0%, and the Ni ratio is diffused on the Fe-Ni. The ratio of the aforementioned Ni amount to the total amount of the Fe amount and the Ni amount on the outermost surface of the layer is expressed in units of atomic%.         The steel sheet for battery outer cans according to claim 1 or 2, wherein the thickness of the Fe-Ni diffusion layer is 0.01 μm or more and less than 0.5 μm.     An outer battery can, which has an Fe-Ni diffusion layer on the inner surface and the outer surface of the steel plate in the shape of the outer battery can, further has an Ni layer on the Fe-Ni diffusion layer on the outer surface side of the steel plate, and the steel plate A part of the Fe-Ni diffusion layer on the outer surface side is a Fe-Ni diffusion layer A converted to a Ni adhesion amount of 50 mg / m ² or more and 500 mg / m ² or less on each side of the steel sheet.     The battery outer can according to claim 4, wherein the Ni ratio on the outermost surface of the Fe-Ni diffusion layer A is 1.0% or more and less than 20.0%, and the Ni ratio is on the Fe-Ni diffusion layer. The ratio of the aforementioned Ni amount to the total amount of the Fe amount and the Ni amount on the outermost surface of the is, and the unit of the Fe amount and the Ni amount is atomic%.         The outer battery can according to claim 4 or 5, wherein the thickness of the Fe-Ni diffusion layer A is 0.01 μm or more and less than 0.5 μm.         The battery outer can according to any one of claims 4 to 6, wherein the thickness of the Ni layer is 1 μm or more.         A battery is provided with the battery outer can according to any one of claims 4 to 7, an electrolyte, an electrode, and a separator disposed inside the battery outer can.