JP3434236B2 - Method for producing aluminum alloy plate for sealed rectangular battery outer can - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery serving as a drive source for a portable electronic device such as a notebook personal computer and a mobile phone, and more particularly to a sealed rectangular battery outer can suitable for a lithium ion secondary battery. The present invention relates to a method for manufacturing an aluminum alloy plate .

[0002]

2. Description of the Related Art In recent years, lithium ion secondary batteries have come to be frequently used as a driving source for portable electronic devices, and the outer can thereof is made of aluminum alloy instead of conventional stainless steel for the purpose of weight reduction. Considered for use. A high-strength aluminum alloy is desired for the outer can to maintain the shape of the battery, but since the high-strength aluminum alloy is inferior in workability, it is necessary to press in multiple stages to form the outer can. However, there is a problem in that it takes a lot of time for molding, and moreover, a lot of punches and dies are required, resulting in high cost.
Therefore, recently, pure aluminum type (JIS
-1000 series) alloy, or Al-Mn series (JIS-3
The application of relatively soft alloys such as (000 series) alloys is being considered.

The aluminum alloy is rolled to a predetermined thickness and then press-molded into the outer can 1 shown in FIG.
In the case of a lithium ion secondary battery, for example, the outer can 1 has a spirally wound electrode body housed therein, and the upper lid 2 is hermetically welded to be processed into a battery. However, the relatively soft aluminum alloy outer can may swell due to an increase in internal pressure due to heat generated when the internal spiral electrode body is charged. When the outer can swells, the gas pressure decreases, the amount of gas absorbed decreases, and the chargeability decreases. Therefore, the swelling rate of the outer can is regulated.
The swelling ratio is determined by setting the inner pressure of the outer can to 2 kg / cm ² and sealingly welding the upper lid, and heating the upper lid at 85 ° C. for 2 hours. The thickness T of the outer can after heating and the thickness of the outer can before heating. The difference from t is T
It is shown by the percentage [(T−t) / T] × 100% of the value divided by (see FIG. 2). In order to prevent this swelling, a method of padding the inner corner portion of the outer can to strengthen it structurally has been studied, but a sufficient effect has not been obtained.

From the above, the inventors of the present invention have researched an aluminum alloy which is relatively soft and has excellent press formability and which is not easily deformed by an increase in internal pressure during charging and has excellent swelling resistance. It was found that the press forming property and the swelling resistance can be made compatible by the -Si-Cu alloy and the alloy containing Fe, and the present invention was completed by carrying out research based on this finding. An object of the present invention is to provide a method for producing an aluminum alloy plate for a sealed rectangular battery outer can, which is excellent in press formability and swelling resistance.

[0005]

The invention according to claim 1 is
Si 0.4-0.6 wt%, Cu 0.15-0.25
wt%, Mn of 1.1 to 1.3 wt%, the balance is Al and Al and unavoidable impurities Al alloy is melted, cast, chamfered,
Homogenization treatment, hot rough rolling, hot finish rolling, cold rolling, time
For the manufacturing method of aluminum alloy plate that is processed into plate material
Then, the homogenization treatment is performed at a temperature of 580 to 620 ° C. for 1 hour.
Heat and apply for ~ 15 hours, then hot finish rolling at 340 ° C.
It is heated at the above temperature and applied, and the aging treatment is 220 to 2
It is a method for producing an aluminum alloy plate for a hermetically sealed rectangular battery outer can, which comprises heating at a temperature of 40 ° C.

According to the second aspect of the present invention, Si is 0.4 to 0.4.
0.6 wt%, 0.15 to 0.25 wt% Cu, 1.1 to 1.3 wt% Mn, 0.3 to 1.0 wt% Fe
Al alloy containing and balance Al and unavoidable impurities
Melting, casting, chamfering, homogenization treatment, hot rough rolling, hot finishing
Aluminum rolled into sheet material after top rolling, cold rolling and aging treatment
In the method for producing aluminum alloy plate, the homogenizing treatment is performed at 580
Heat at a temperature of ~ 620 ° C for 1 to 15 hours and apply the heat.
Inter-finish rolling is performed by heating at a temperature of 340 ° C. or higher, and
A method for producing an aluminum alloy plate for a sealed type rectangular battery outer can, which comprises performing an aging treatment by heating at a temperature of 220 to 240 ° C.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, Si precipitates by aging treatment and improves swelling resistance. Its content is 0.
The reason for defining 4 to 0.6 wt% is that if less than 0.4 wt%, the effect is not sufficiently obtained, and if it exceeds 0.6 wt%, the crystallized material becomes coarse and press formability deteriorates. .

Like Cu, Cu precipitates by aging treatment and improves swelling resistance. Its content is 0.15 to 0.
The reason for defining 25 is that if it is less than 0.15 wt%, its effect is not sufficiently obtained, and if it exceeds 0.25 wt%, the strength becomes too high and the press formability deteriorates.

In the aging treatment, Si and Cu which are solid-dissolved in the aluminum matrix are deposited, and these deposits prevent the movement of dislocations that move due to heat generation during charging, and prevent the outer can from swelling. .

Mn contributes to the improvement of strength, refines the crystal grains to improve the press formability, and prevents the roughening of the alloy sheet. The reason for defining the content to be 1.1 to 1.3 wt% is that if the content is less than 1.1 wt%, the crystal grains do not become sufficiently fine,
This is because problems such as rough skin and press formability occur, and when the content exceeds 1.3 wt%, crystallized substances become coarse and the press formability deteriorates.

Fe enhances strength and prevents deformation of the outer can. The reason for defining the content to be 0.3 to 1.0 wt% is that the effect is not sufficiently obtained if it is less than 0.3 wt%,
This is because if it exceeds 1.0 wt%, the press formability is reduced.

Next, a method for manufacturing an aluminum alloy plate according to the first aspect of the present invention will be described. Claim 1 An aluminum alloy having the composition defined in the invention is melted and cast by a semi-continuous casting method or the like, and the obtained ingot is chamfered, homogenized, hot rough rolled, hot finish rolled, cold rolled ( appropriately add intermediate annealing) to produce subjected to aging treatment.

[0013] In here, homogenization treatment is to increase the solid solution amount of Si and Cu in the ingot, promoting age hardening of Si and Cu in the aging treatment after. The reason why the homogenization treatment is performed by heating at 580 to 620 ° C. for 1 to 15 hours is as follows.
At less than 580 ° C. or less than 1 hour, Si and Cu do not form a solid solution sufficiently, and the swelling resistance is not improved even after aging treatment.
This is because if the temperature exceeds 20 ° C, there is a danger of local melting, and even if heating is performed for more than 15 hours, the effect is saturated.

In the present invention, the hot finish rolling temperature is set to 3
The reason for prescribing at 40 ° C. or higher is that if the temperature is lower than 340 ° C., the recrystallization in hot finish rolling becomes incomplete, and as a result, the solid solution amount of Si and Cu decreases, and the swelling resistance improves even after aging. This is because it is not done.

In the present invention, Si and Cu are used in the aging treatment.
Is finely deposited to prevent movement of dislocations in the outer can during charging and prevent expansion of the outer can. The reason for defining the temperature of the aging treatment at 220 to 240 ° C. is that Si and Cu are not sufficiently precipitated below 220 ° C., and the precipitates are coarsened above 240 ° C., and age hardening is not possible in any case. This is because the blistering resistance is sufficient and the swelling resistance is not improved. If the precipitate becomes coarse, press formability also deteriorates.

The invention according to claim 2 defines the invention according to claim 1.
A method for manufacturing an aluminum alloy sheet in which an appropriate amount of Fe is further added to an aluminum alloy having a composition , and the reason for defining each condition of homogenization treatment, hot finish rolling, and aging treatment is defined in Claim 1.
This is the same as the case of the described invention.

[0017]

EXAMPLES The present invention will be described in detail below with reference to examples. (Example 1) Si, Cu, Mn, or further Fe was added to an industrial aluminum ingot (class 1) specified in JIS H2102 to melt an aluminum alloy having the composition defined in the present invention shown in Table 1, and A semi-continuous casting method is used to cast an ingot, and the ingot is homogenized at 600 ° C. for 4 hours, and then hot rough rolling and hot finish rolling (starting temperature 500 ° C., ending temperature 350 ° C.) are performed. It is continuously applied to form a hot finish rolled plate with a thickness of 2.5 mm, and then this hot finish rolled plate is 0.3 mm in thickness.
Cold-rolled, and then aged at a temperature of 230 ° C. to produce an aluminum alloy plate.

Comparative Example 1 The same method as in Example 1 was repeated except that Si, Cu, Mn, or Fe was added to the industrial aluminum ingot to use an aluminum alloy having a comparative composition shown in Table 2. An aluminum alloy plate for a sealed lithium-ion secondary battery outer can was manufactured.

With respect to each aluminum alloy plate obtained in Example 1 and Comparative Example 1, press formability and swelling resistance were examined. The press moldability was evaluated as good (∘) when cracks did not occur after the multi-stage molding, and as bad (x) when cracks occurred. The swelling resistance is determined by pressing each of the aluminum alloy plates into an outer can, adjusting the inner pressure of the outer can to 2 kg / cm ² , and sealingly welding the upper lid.
After heating at 5 ° C for 2 hours, measure the thickness T of the outer can,
The difference from the thickness t of the outer can before heating was divided by T to obtain a percentage [(T−t) / T] × 100% (see FIG. 2), and H
Was less than 1%, the blistering resistance was good (∘), and more than 1% was poor (x). The results are also shown in Tables 1 and 2.

[0020]

[Table 1]

[0021]

[Table 2]

As is clear from Table 1, all the aluminum alloy sheets having the composition defined by the present invention were excellent in press formability and swelling resistance. On the other hand, the aluminum alloy sheets of comparative composition shown in Table 2 were all inferior in swelling resistance and / or press formability. This is because all of the values are out of the specified values of the present invention.

(Example 2) Of the aluminum alloys of the composition specified in the present invention shown in Table 1,
The No. 1 alloy is melted and cast by a semi-continuous casting method to form an ingot, which is then subjected to homogenization treatment for 4 hours at various temperature changes, and then hot working by a normal method. Rough rolling is performed, and then hot finish rolling is performed at a starting temperature of 500 ° C. and various ending temperatures to obtain a hot finishing rolled plate having a thickness of 2.5 mm, and then this rolled plate is 0.3 mm in thickness. It was cold-rolled and then aged at various temperatures to produce aluminum alloy sheets. The homogenization treatment temperature, the hot finish rolling end temperature, and the aging treatment temperature were changed within the specified values of the present invention.

(Comparative Example 2) A sealed lithium-ion secondary battery outer can according to the same method as in Example 2 except that the homogenizing treatment, hot finish rolling, and aging treatment were performed under the conditions outside the specified values of the present invention. Aluminum alloy plate for use was manufactured.

With respect to each of the alloy plates obtained in Example 2 and Comparative Example 2, press formability and swelling resistance were examined in the same manner as in Example 1. The results are shown in Table 3.

[0026]

[Table 3]

As is clear from Table 3, No.
All of 21 to 25 were excellent in press formability and swelling resistance. On the other hand, Nos. 26 to 30 of Comparative Examples have swelling resistance, or press moldability and swelling resistance, because the homogenizing heat treatment temperature, the hot finish rolling finish temperature, and the aging treatment temperature are outside the specified values of the present invention. Was inferior.

[0028]

As described above, the manufacturing method according to the present invention
Sealed prismatic battery outer can for aluminum alloy sheet that is the S
i, Cu, Mn in appropriate amounts, or F
e is contained in an appropriate amount, and the Si and Cu precipitate to prevent movement of dislocations in the aluminum alloy forming the outer can. Therefore, the heat generated during charging does not cause the outer can to swell. Further, the outer can has excellent press formability. Further, the aluminum alloy plate can be easily manufactured by defining the conditions of homogenization treatment, hot finish rolling, and aging treatment. Therefore, it has a remarkable industrial effect.

[Brief description of drawings]

FIG. 1 is a perspective view of a sealed type prismatic battery outer can with a top cover.

2A is a cross-sectional view taken along the line AA of the outer can shown in FIG.
(B) is an AA cross-sectional view after heating the outer can shown in FIG. 1.

[Explanation of symbols]

1 Sealed square battery exterior can 2 Top lid 3 Exterior cans before heating 4 Exterior cans after heating T Thickness of outer can before heating t Thickness of outer can after heating

Claims (2)

(57) [Claims] 1. Si is 0.4 to 0.6 wt%, Cu is 0.
Al alloy containing 15 to 0.25 wt% and Mn of 1.1 to 1.3 wt% with the balance Al and unavoidable impurities, melting, casting, chamfering, homogenizing treatment, hot rough rolling, hot finishing In the method for producing an aluminum alloy sheet that is rolled, cold rolled, or aged to obtain a sheet material, the homogenizing treatment is performed at 580 to 6
The method is characterized in that heating is carried out at a temperature of 20 ° C. for 1 to 15 hours, the hot finish rolling is carried out by heating at a temperature of 340 ° C. or higher, and the aging treatment is carried out by heating at a temperature of 220 to 240 ° C. A method for producing an aluminum alloy plate for a sealed rectangular battery outer can. 2. Si to 0.4 to 0.6 wt% and Cu to 0.
15-0.25 wt%, Mn 1.1-1.3 wt%, Fe 0.3-1.0 wt%, the balance Al, Al and inevitable impurities are melted, cast, chamfered , Homogenizing treatment, hot rough rolling, hot finish rolling, cold rolling, aging treatment for producing an aluminum alloy sheet, wherein the homogenizing treatment is performed at a temperature of 580 to 620 ° C.
After heating for 15 hours, the hot finish rolling is performed by heating at a temperature of 340 ° C. or higher, and the aging treatment is 220 to 24.
A method for producing an aluminum alloy plate for a sealed rectangular battery outer can, which comprises heating at a temperature of 0 ° C.