JP2001307686A - Battery can, its manufacturing method and battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery can that is easy in laser-sealing, can prevent the reduction of pressure-resistant strength of the plug port and can achieve thinning and weight reduction of the can, and to provide a battery that can improve mass-energy density and weight-energy density. SOLUTION: This battery can is formed in a cylindrical shape with a bottom, and its has a two-layer structure in which the materials excluding that used for the circumference of the plug port of the battery can are different metals or alloys. The material of the plug-port circumference is either one of the materials for the two-layer structure excluding the plug-port circumference. The battery can is formed so that the ratio of bottom thickness/flank- circumference thickness may be 1.2 to 5.0. In this way, laser plugging becomes easier, reduction of pressure-resistant strength of the plug port can be prevented, thinning and weight reduction of the battery can may be achieved, and mass- energy density and weight-energy density of the battery can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery can having improved volume energy density and weight energy density or safety by improving the structure of the battery can, a method for manufacturing the same, and a battery.

[0002]

2. Description of the Related Art As devices using batteries, especially portable devices such as mobile phones, have become smaller and lighter, there is a demand for an improvement in the energy density of batteries. For batteries having a standardized outer size, it is desired that the batteries have a higher energy density and a lighter weight even with the same standard size. As an index indicating the energy density of the battery,
Volume energy density (Wh /
1) and a weight energy density (Wh / kg) which is an index of weight reduction of the battery.

An important factor that determines the energy density of a battery is a power generating element mainly composed of a positive electrode and a negative electrode active material, an electrolyte, and the like. The degree of contribution to the improvement of the weight energy density is not small. That is, by reducing the thickness of the battery can, it is possible to increase the volume of the battery can whose external dimensions are standardized, and to improve the volume energy density of the entire battery due to an increase in the capacity of the power generating element. I do. In addition, the weight of the battery can is reduced by reducing the weight of the battery can, and the weight energy density can be improved. At present, the weight ratio of the battery can to the total weight of the battery is 10 to 20 wt% for a nickel-metal hydride battery or a lithium ion secondary battery in the case of a cylindrical battery.
%. In the case of a prismatic battery, it is necessary to increase the thickness of the battery can in order to obtain pressure resistance, so that 30 to 40 wt.
%. By reducing this weight ratio, the weight energy density can be improved.

[0004] In order to reduce the thickness and weight of the battery can, various improvements have been made to the materials and processing techniques used for the battery can. For a rectangular lithium ion secondary battery, aluminum or aluminum alloy is used as the battery can material. It is possible to reduce the weight ratio to 20 to 30% by weight. In addition, as a manufacturing method for processing a battery can into a bottomed cylindrical shape, for example, as described in Japanese Patent Publication No. 7-99686, a DI (Drawing and Ironing) method using a combination of drawing and squeezing is used. In addition to improving productivity by reducing the number of manufacturing processes, it is also possible to reduce the thickness of aluminum-killed steel (S
When PCE material is used, the volume energy density of the battery is improved by 2 to 5%.

[0005]

In order to ensure the reliability and safety of the battery, maintaining the strength of the battery can is an indispensable element, and the energy density cannot be improved at the expense of the strength. For primary batteries, ensure capacity during long-term storage and prevent liquid leakage or obtain stable discharge characteristics.For secondary batteries, in addition to the elements required for primary batteries, the cycle life and safety of charging and discharging, and the internal pressure of batteries It is necessary to maintain a strength capable of coping with the bulging deformation caused by the rise of the height. In addition, since the type of electrolyte used varies depending on the type of battery, the material used for the battery can must have corrosion resistance to the electrolyte, and it is not easy to select a material for forming the battery can. Can not.

Accordingly, in order to improve the energy density while securing the strength, a material having a high strength, a light weight and a high corrosion resistance is required. However, a material satisfying this requirement is still being developed. Absent. At present, there are iron sheet materials such as aluminum-killed steel and aluminum-based materials such as aluminum alloys as materials used for battery cans, and each has advantages and disadvantages as battery cans. That is, the aluminum-killed steel has a Young's modulus of about 2,000.
Since it is 0 kgf / mm ² , the thickness of the battery can can be reduced, and the volume energy density can be improved. However, the specific gravity of the battery can is about 7.8, which leads to an increase in the weight of the battery can. Energy density cannot be improved. On the other hand, in the case of the aluminum alloy, its specific gravity is about 2.7, but its Young's modulus is about 7000 kgf /
Because it is mm ^2, the rigidity of which can contribute to weight reduction is poor, it is necessary to form the thickness to obtain the strength of the battery can, the volume energy density decreases, also the weight in terms of weight energy density I can't make the most of it.

[0007] In order to make use of the characteristics of the steel sheet material and the aluminum-based material, attempts have been made to use a material formed of these materials in a clad material as a battery can, as disclosed in Japanese Patent Application Laid-Open No. 2000-30673. ing. However, since the entire battery can is made of clad material, the strength of the battery can sealing portion is insufficient, or when using laser sealing, the sealing portion is made of dissimilar metal, so the melting temperature is different and adjustment is difficult and difficult. Due to difficulties in work, the development of an effective battery can using a clad material has not been achieved.

It is an object of the present invention to prevent a decrease in sealing pressure resistance, to reduce the thickness and weight of a battery can that can be easily sealed with a laser, and to improve the volume energy density and weight energy density of the battery. The present invention provides a battery can, a method of manufacturing the same, and a battery.

[0009]

The battery can of the present invention for solving the above-mentioned problems is a battery can formed in a cylindrical shape with a bottom, and the material other than the peripheral surface of the sealing portion of the battery can is used. It has a two-layer structure of a different metal or a different alloy, and the peripheral surface material of the sealing portion is made of any one of the two-layer structure materials other than the peripheral surface of the sealing portion, and the ratio of bottom surface thickness / side peripheral surface thickness is 1. A battery can formed to be 2 to 5.0. According to the above configuration, mutual advantages are obtained by using a two-layer structure material of a dissimilar metal or a dissimilar alloy except for the peripheral surface of the sealing portion. No adjustment is required, and laser sealing becomes easy. When the bottom thickness / side peripheral thickness ratio is less than 1.2, the amount of material used increases and it is difficult to put the battery can to practical use. When the ratio is 5.0 or more, the battery can is processed into a required shape. Can not do it. Therefore, the ratio of the bottom surface thickness / side peripheral surface thickness is preferably 1.2 to 5.0.

Further, by using aluminum or an aluminum alloy for one layer of the two-layer structure material, its specific gravity is as small as about 2.7, which can contribute to weight reduction.

Further, the aluminum-based material layer has a thickness of 0.5 to
By forming from an aluminum alloy containing 2.5 wt% of manganese, can-making properties are improved and strength of the battery can is also improved.

Further, by using an iron steel sheet for one layer of the two-layer structure material, the Young's modulus is about 20,000 kgf / mm ^2.
Therefore, the thickness of the battery can can be reduced.
In addition, by using an iron steel sheet as the material for the peripheral surface of the sealing portion, it is possible to obtain the same strength as that of a battery can made of a single iron steel sheet material in the sealing portion, which requires particularly high strength as a battery can.

Further, since the steel sheet material layer is made of cold-rolled carbon steel having a carbon content of 0.1 wt% or less, the can-making property is improved. Can be eliminated. In particular, 0.05% by weight or less is preferable for smooth squeezing.

In addition, stainless steel such as SUS304 and SUS430 can be used as one layer of a two-layer structure material. When the stainless steel is disposed on the inner surface side of the battery can, the corrosion resistance against the electrolytic solution can be reduced. When placed on the side, the corrosion resistance during storage can be improved.

Further, by providing a nickel layer on both sides or one side of the steel sheet material layer, the bondability between the steel sheet material and another metal material, particularly the bondability with an aluminum-based material, is improved, and DI processing is performed. Thus, a battery can of stable quality can be manufactured. In addition, since the nickel layer is provided on the surface of the steel sheet material layer, the corrosion resistance to an alkaline electrolyte is improved, and a battery can is manufactured with the steel sheet material on the inner side, and used as a battery can for a nickel-metal hydride storage battery or the like. Suitable for application.

Further, when the same material as the peripheral surface of the sealing portion is used as the outer surface of the battery can, since the inner surface of the battery can is made of a dissimilar metal,
When a local battery is formed and self-discharge is likely to occur, it is necessary to take measures such as preventing the electrolytic solution from climbing up when using this configuration. Therefore, it is preferable that the same material as the peripheral surface of the sealing portion be the inner surface of the battery can.

By forming the peripheral surface of the sealing portion of the battery can to be 10% or more thicker than the other peripheral surfaces, the pressure resistance can be increased without lowering the volume.

Further, the battery can of the present invention has a two-layer structure of steel sheet and aluminum or aluminum alloy except for the peripheral surface of the sealing portion of the battery can, and the material of the peripheral surface of the sealing portion is a two-layer structure other than the peripheral surface of the sealing portion. The battery can is made of any one of the materials, and is formed such that the ratio of bottom surface thickness / side peripheral surface thickness is 1.2 to 5.0.

Since the portion for accommodating the power generating element is formed by a two-layer structure in which an aluminum-based material and a steel sheet material are joined, all of the conventional steel sheet materials are used due to the lightness of the aluminum-based material and the rigidity of the steel sheet material. Compared to a battery can of the same material or a battery can of the same size, the battery can is formed of a lighter weight and higher strength, even if the thickness is the same. This weight reduction can improve the weight energy density. In addition, since the coefficient of thermal expansion differs between aluminum-based materials and steel sheet materials, when this battery can is applied to a secondary battery, the battery can undergo swelling deformation due to an increase in internal pressure due to a rise in temperature during charging. Bending stress acts in the direction of suppressing the bulging deformation, so that the required deformation strength can be maintained even if the side peripheral surface is formed thin.

Further, when the material of the peripheral surface of the sealing portion is a steel plate material, the strength of the sealing portion is equivalent to that of a conventional battery can made entirely of a steel plate material.

When the same material as the peripheral surface of the sealing portion is used as the outer surface of the battery can, since the inner surface of the battery can is made of a dissimilar metal, a local battery may be formed and self-discharge may occur. If used, it is necessary to take measures such as preventing the electrolyte solution from climbing up. Therefore, it is preferable that the same material as the peripheral surface of the sealing portion be the inner surface of the battery can.

Therefore, when the battery can is formed in a cylindrical shape with a bottom using an aluminum-based material as the peripheral surface material of the sealing portion, the outer surface other than the peripheral surface of the sealing portion is made of an iron-based material, so that it is hardly damaged and durable. It will be excellent in property.

In view of the above, a battery can is formed in a two-layer structure with an aluminum-based material such that the steel sheet material is used as a sealing portion and the steel sheet material is on the inner surface side of the battery can. Nickel plating is applied to the surface of the steel sheet material layer on the inner side to ensure corrosion resistance to the electrolytic solution, and by configuring the battery can to be the negative electrode of the battery, both the weight energy density and the volume energy density are large, and A battery having high battery strength and excellent in corrosion resistance during storage can be formed. In addition, since the aluminum-based material is on the outer surface side other than the peripheral surface of the sealing portion, the weldability to the battery can is improved.

In the first manufacturing method of the present invention, a cup-shaped intermediate product formed by drawing a material formed by bonding two layers of dissimilar metals to a portion having a two-layer structure is subjected to squeezing or drawing and squeezing. This is a method for manufacturing a battery can produced by the above method.

In the second manufacturing method of the present invention, a metal can or a metal alloy material having a two-layer structure is formed into a bottomed cylindrical shape and then fitted, and then subjected to squeezing or drawing and squeezing to form a battery can. It is a manufacturing method.

A battery can formed in a cylindrical shape with a bottom is formed by drawing a material formed of a plurality of layers at necessary portions of a dissimilar metal by a press machine to form a cup-shaped intermediate product or dissimilar metal. Each of the cup-shaped intermediate products is individually formed on a cup-shaped intermediate product, and the cup-shaped intermediate product is squeezed using a drawing die and a squeezing die. It is characterized in that it is formed in a bottomed cylindrical shape having a thickness of 0.0.

Further, the present invention is a battery in which a power generation element is housed in the battery can.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.
The embodiment described below is an example embodying the present invention, and does not limit the technical scope of the present invention.

The battery can according to the present embodiment is characterized in that a steel plate material and an aluminum-based material are used for a necessary portion of the battery can for accommodating a power generating element. In addition to verifying the effectiveness as a battery can having a different composition, the present invention was conducted to verify the appropriate configuration for forming a battery can by changing the type and shape of a battery to be applied.

First, in order to construct an AA size nickel-metal hydride battery, the battery can was finished with an outer diameter of 13.8 m.
mφ, a cylindrical shape with a bottom having a height of 49.0 mm, in which a power generating element is housed to form a nickel-metal hydride storage battery.
An embodiment will be described.

In FIG. 1, a nickel-metal hydride storage battery 1
The power generation element 3 is accommodated in the battery can 2, and the opening end of the battery can 2 is sealed with a sealing plate 4. The battery can 2 used for the nickel-metal hydride battery 1 is a battery can using a steel plate material on the peripheral surface of the sealing portion and the inner surface of the can, and a battery can using an aluminum-based material on the outer surface of the can except for the peripheral surface of the sealing portion. Manufactured to be.

In FIG. 2A, both sides have a thickness of 2.5 μm.
Nickel-plated aluminum-killed steel 5 having a thickness of 400 μm and a carbon content of 0.04 wt% (hereinafter referred to as SPC
E material) to an outer diameter of 40 mmφ and a depth of 20 mm
A hole having a diameter of 0 μm and a diameter of 25 mm is machined. Thereafter, a pure aluminum material 6 (equivalent to JIS-A1050) having a thickness of 200 μm and a diameter of 25 mm is attached to the center hole of this processed product to form a starting material for forming a battery can.

This starting material was drawn by a press so that the pure aluminum material 6 bonded to the outer surface side of the battery can was exposed as shown in FIG.
It is formed into a cup-shaped intermediate product 7 having a diameter of 5 mm and a height of 15.5 mm. In this state, the thickness of the bottom surface and the thickness of the side peripheral surface hardly change from the starting material.

The cup-shaped intermediate product 7 thus formed
Is sent to a DI processing step as shown in FIG. 3 and formed into a bottomed cylindrical shape having a side peripheral surface having a predetermined height by drawing and squeezing. In this DI method, the cup-shaped intermediate product 7 is drawn by a punch 8 and drawn by a die 9 and a squeeze die 10, 10
Are extruded into a row of dies arranged in a straight line, thereby forming a drawing die 9 in which dies are arranged so that the inner diameter thereof decreases in the advance direction of the punch 8, and each of the squeezing dies 10
Every time the cup-shaped intermediate product 7 is pushed into the inside, a squeezing and squeezing are added, and the battery can 2 is formed into a bottomed cylindrical battery can 2 having a predetermined size in one step. In the state where the DI processing was performed, the outer diameter was 13.8 mmφ and the height was 54 mm, and the opening end side was not flat but wavy.
The ear at the opening end is cut so as to have a set height of 49.0 mm.

FIG. 4 shows the vertical cross-sectional shape of the battery can 2 formed by the above-mentioned DI method. The thickness of the bottom surface 2a is 400 μm, the thickness of the side peripheral surface 2b is 150 μm, and the peripheral surface 2c of the sealing portion 2c. It is formed in a cylindrical shape with a bottom of 180 μm. Therefore, the squeeze rate in DI processing of the battery can 2 is 63%. In addition, the stiffening rate is expressed as “slashing rate (%) =
(Original thickness−thickness after squeezing) × 100 / original thickness ”. Further, the ratio of the bottom surface thickness / side peripheral surface thickness is 2.67.
And weighs about 3.1 g. Incidentally, when a battery can of the same shape and the same size was formed of a single material of SPCE material, the weight was about 3.6 g, which means that a weight reduction of about 14% was achieved.

Further, since the inner surface of the battery is made of a steel sheet material, the battery has excellent swelling and sealing pressure resistance when the internal pressure of the battery increases.

In order to obtain a sealing strength in which the opening end is sealed with a sealing plate after the power generation element or the like is housed in the battery can 2, the sealing portion peripheral surface 2c is about 20% thicker than the side peripheral surface 2b. It is formed thick. When the internal pressure of the battery rises, the sealing portion becomes the weakest portion in terms of pressure resistance, so the side peripheral surface 2b
By forming it thicker, the pressure resistance by the sealing can be further enhanced. Then, the thickness of the side peripheral surface 2b can be minimized so that swelling deformation can be suppressed.
As shown in FIG. 3B, a method of forming the sealing portion peripheral surface 2c thicker than the side peripheral surface 2b is to increase the diameter of the punch 8 in the DI mold at the position of the sealing portion peripheral surface 2c. By forming the sealing portion smaller by a length corresponding to the length, the sealing portion is pushed inward when the diameter of the punch 8 is reduced when passing through the squeeze die 10, and the sealing portion peripheral surface 2c is formed thicker than the side peripheral surface 2b. Is done.

The battery can 2 formed as described above
Is made of aluminum material, and the peripheral material of the sealing part is all steel sheet material, so it can compensate for the low sealing pressure strength seen in the cladding material that partially uses aluminum material with low Young's modulus. it can. Therefore, the same sealing pressure as that of a conventional battery can of the same dimensions, which is entirely formed of a steel sheet material, can be obtained. Further, when the battery can 2 is applied to a secondary battery, the swelling deformation of the battery body caused by an increase in internal pressure due to a rise in temperature during charging is caused by a difference in thermal expansion coefficient between the aluminum-based material and the steel sheet material. Since the bending stress acts as a stress for deforming the side peripheral surface 2b of the battery can 2 inward, an effect of suppressing the swelling deformation of the battery can 2 can be obtained.

In order to manufacture a nickel-metal hydride storage battery using the battery can 2 having the above structure, the following power generating elements are housed in the battery can 2.

First, the positive electrode is prepared by mixing spherical nickel hydroxide powder and additives such as zinc oxide, cobalt oxide, and cobalt hydroxide into a paste, filling the mixture into a sponge-like nickel conductive porous body, and then drying the mixture. , By pressing and cutting to obtain a positive electrode plate.

The negative electrode was made of AB ₅ as a hydrogen storage alloy.
Type MmNi _3.6 Mn _0.4 Al _0.3 Co _0.7 alloy powder with a conductive agent and binder added to form a paste, applied to a nickel-plated iron material punched metal core, dried, pressed and cut To form a negative electrode plate. The positive electrode plate and the negative electrode plate are wound through a separator made of a sulfone-processed polypropylene nonwoven fabric, and housed in the battery can 2. At this time,
The outermost peripheral surface of the negative electrode plate is brought into direct contact with the inner surface of the battery can 2, and the lead is pulled out from the positive electrode plate and spot-welded to the positive electrode terminal provided on the sealing cap.

Next, 2.0 cc of an aqueous potassium hydroxide (KOH) solution having a specific gravity of 1.30 by dissolving 40 g / l of lithium hydroxide (LiOH.H ₂ O) as an electrolytic solution in the battery can 2 was injected. Liquid. Thereafter, in order to seal the open end of the battery can 2 with the sealing cap, the sealing cap is attached by caulking the sealing portion peripheral surface 2c.
The inside is hermetically sealed to complete the nickel-metal hydride storage battery. The battery weight of the AA-size nickel-metal hydride battery thus manufactured is about 25 g, and the battery capacity is 1350 mAh.

The battery can 2 manufactured as the first embodiment is referred to as (battery can 2A). In order to consider the suitability of the battery can 2A, the composition and processing method are changed to change the battery cans 2B to 2B of the same standard size. 2G was manufactured, and a nickel-metal hydride storage battery was similarly manufactured using each of the battery cans 2B to 2G. Hereinafter, each of the battery cans 2B to 2G will be described while being compared and verified with the battery can 2A.

(Battery Can 2B) The battery can 2B is configured to verify the effectiveness of applying nickel plating to the surface of the steel sheet of the constituent material. 400μm thick SPCE material (carbon content 0.04wt%) and thickness 200
Using a pure aluminum material of μm (equivalent to JIS-A1050), DI processing was performed in the same manner as the battery can 2A to form the same size as that shown in FIG. The only difference from the battery can 2A is that both surfaces of the SPCE material are not nickel-plated, and the other configurations are the same. Accordingly, the ratio of the bottom surface thickness / side peripheral surface thickness (2.67) and the squeeze rate (63
%) And weight (3.1 g) are almost the same as those of the battery can 2A.

In the above configuration, it was found that drawing and squeezing in DI processing, which is a can manufacturing process of the battery can 2B, were not always smooth, and that can manufacturing defects were slightly more likely to occur as compared with the case of the battery can 2A. . This is because
It is considered that the absence of the nickel plating layer weakens the bonding strength between the aluminum-based material and the steel sheet material, and the absence of the nickel plating layer on the contact surface with the DI mold.

When the battery can 2B is applied to an alkaline storage battery such as a nickel-metal hydride storage battery, charging characteristics, discharge characteristics, and cycle life characteristics which are presumed to be caused by progress of corrosion by an alkaline electrolyte due to the absence of a nickel plating layer. ,
The storage characteristics deteriorated. However, when applied to a lithium ion secondary battery or the like using an organic electrolyte, there is no problem at all, and it can be said that there is utility as a battery can except for a decrease in workability of DI processing.

(Battery Can 2C) The battery can 2C was obtained by verifying the workability of can making by the DI method based on the carbon content of the steel sheet material constituting the battery can 2C. 400 μm, carbon content: 0.11
In the same manner as the battery can 2A, DI processing was performed with the SPCE material of wt% and a pure aluminum material (equivalent to JIS-A1050) having a thickness of 200 μm to have the same size as that shown in FIG. The same bottom surface thickness / side peripheral surface thickness ratio as that of the battery can 2A (2.
67), squeezing rate (63%), weight (3.1g), but SPCE material with carbon content of more than 0.1wt% has difficulty in DI processing and is problematic in workability for manufacturing battery cans And could not be used as a suitable battery can material.

(Battery Can 2D) The battery can 2D is obtained by verifying DI workability, weldability, and the like based on the manganese content of the aluminum-based material constituting the battery can 2D. A battery can was formed using a 0.4 wt% aluminum alloy. Other configurations are the same as the battery can 2A. In the case of this battery can 2D, the hardness was low as an aluminum alloy due to the low content of manganese, and there was a problem in the can-making properties by DI processing, and the intended configuration could not be obtained.

(Battery Can 2E) The battery can 2E uses an aluminum alloy having a high manganese content of 2.6 wt% as opposed to the battery can 2D. However, the workability and weldability at the time of assembling the battery were poor, and the desired configuration could not be obtained.

(Battery can 2F) The battery can 2F is a battery can 2A
This is configured as a comparative example for comparing with a battery can of all clad materials using two types of clad materials used in the above, and has the same shape and dimensions as the battery can 2 shown in FIG.
This is the result of I processing. There was no problem in the can-making properties, and the same performance as that using the battery can 2A was obtained even when a battery was formed. However, since the battery can was formed by using the clad material, the sealing portion peripheral surface materials were the SPCE material and the aluminum material, so that the sealing pressure resistance was lower than that of the battery can 2A.

(Battery Can 2G) In order to verify the proper range of the cylindrical bottom surface thickness / side peripheral surface thickness ratio, the battery can 2G is made by DI processing using the same material as the battery can 2A. It was produced at different rates. When the side peripheral surface thickness is formed to be 360 μm with respect to the bottom surface thickness of 400 μm, the bottom surface thickness at this time /
The side peripheral surface thickness ratio is 1.1 and the squeeze rate is 10%, which increases the amount of material used and is not practical. Further, since the effective volume in the battery can is reduced, the volume energy density is reduced by about 6% as compared with the battery can 2A. In order to increase the volume energy density, it is effective to reduce the thickness of the side peripheral surface.
An attempt was made to manufacture a battery can having a side peripheral surface thickness as thin as 60 μm. In this case, the ratio of the thickness of the bottom surface to the thickness of the side peripheral surface was 6.7, and the squeeze rate was as large as 85%. As a result of verification, when the ratio of bottom surface thickness / side peripheral surface thickness is 1.2 or less, the effective volume in the battery can is reduced, resulting in a large decrease in volume energy density, and is required at 5.0 or more. The appropriate value was 1.2 to 5.0 because the shape could not be processed.

The battery cans 2B to 2G according to the above embodiments.
It can be seen from the verification that the configuration shown in Example 1 is appropriate as the battery can 2 applied to the AA-size nickel-metal hydride storage battery. Compared to conventional battery cans using clad material, the peripheral material of the sealing part is not SPCE material and aluminum clad material, but all are SPCE material, so the sealing pressure resistance is high and the weight is also reduced by aluminum. The effectiveness of being able to produce a battery can by DI processing is shown.

As the starting material, as shown in FIG. 5, cup-shaped intermediate products each having a different outer diameter may be used. As an example, a cup-shaped intermediate product 11 made of SPCE material and a cup-shaped intermediate product 12 made of an aluminum material having an inner diameter larger than the outer diameter of the cup intermediate product 11 are fitted and processed at the same time as DI processing, so that the battery can 2 is substantially the same as the battery can 2. You can get things.

Next, in order to form a prismatic lithium ion secondary battery, the battery can was finished with a bottom size of 22 ×
A second embodiment in which a lithium ion secondary battery is formed in a bottomed square cylindrical shape having a height of 8 mm and a height of 48.0 mm and accommodating a power generation element therein will be described.

In FIG. 6, the lithium ion secondary battery 1
Reference numeral 3 denotes a battery case in which the power generation element 15 is housed in the battery
4 is formed by sealing the open end of the cover 4 with a sealing cap 16.
The battery can 14 used in the lithium ion secondary battery 13 is made of an aluminum-based material and a steel sheet material, and is manufactured as described below.

An aluminum alloy having a thickness of 450 μm (JI
A battery can is formed by employing an SPCE material having a thickness of 250 μm and a carbon content of 0.03 wt% heat-treated by applying nickel plating to a thickness of 3.5 μm on both surfaces and heat-treating the same.

An aluminum alloy is cut out in a circular shape, and a hole having a depth of 250 μm is formed in the center thereof. 250 μm thickness, carbon content: 0.03 wt in the center hole of this processed product
% Of SPCE material, and battery can 1 as well as battery can 2
4 as a starting material. The SPCE material bonded to the outer surface side of the battery can 14 is drawn out by a press machine so that the SPCE material bonded to the battery can 14 is formed to form a cup-shaped intermediate product. In this state, the starting material hardly changes in both the bottom thickness and the side thickness. The cup-shaped intermediate product thus formed is sent to a DI processing step similar to that shown in FIG. 3, and is formed into a bottomed square cylindrical shape having a predetermined height by drawing and squeezing. When DI processing is performed, the bottom size is 22 × 8
mm and the height is 52 mm, and the opening end side is not flat but wavy. Therefore, the ear portion on the opening end side is cut so as to have the set height dimension of the battery can of 48 mm.

FIG. 7 shows the vertical cross-sectional shape of the rectangular battery can 14 manufactured by the above-described processing method.
a has a thickness of 450 μm, and the side peripheral surface 14 b has a thickness of 200 μm.
m, and the ratio of bottom surface thickness / side peripheral surface thickness is 2.2.
5. The squeeze rate is 56%. Also, the battery can 14
2 is 30% thicker than the side peripheral surface 14b.
It is formed to a thickness of 50 μm to improve the sealing strength.

The corner rising from the bottom surface 14a to the side peripheral surface 14b is formed as a curved surface having a radius of curvature of 0.35 mm. The larger the radius of curvature, the better the battery can 1
4, the curvature radius is desirably small in order to secure the effective volume of the power generating element housed in the battery can 14, and is 0.5 mm or less in consideration of the strength retention and the volume securing. Is desirable.

In order to manufacture the lithium ion secondary battery 13 using the battery can 14 configured as described above, a power generation element 15 as described below is accommodated in the battery can 14.

For the positive electrode, LiCoO _{2 as} a conductive agent, acetylene black, a fluororesin as a binder and the like are mixed in a paste form, and this is applied to an aluminum foil substrate.
The positive electrode plate is formed to a predetermined size by drying, pressing, and cutting. The negative electrode was prepared by adding a styrene-butadiene rubber binder, a carboxymethylcellulose thickener, etc. to spherical graphite, and then applying the paste to a copper foil substrate. Formed on a plate. The positive electrode plate and the negative electrode plate are wound through a separator formed of a microporous polyethylene film and housed in the battery can 14,
The sealing cap 16 serving as the negative electrode terminal of the lithium ion secondary battery and the negative electrode plate are connected with the lead, and the battery can 14 serving as the positive electrode terminal is connected with the lead. This battery can 14
An electrolytic solution obtained by dissolving lithium hexafluorophosphate at a concentration of 1 mol / 1 in a mixture of ethylene carbonate and diethyl carbonate at a molar ratio of 1: 3 was injected into the inside, and a sealing cap was attached to the open end of the battery can 14. 16 and battery can 1
The space between 4 and the sealing cap 16 is sealed by laser sealing.

The lithium ion secondary battery 13 manufactured as described above has a width of 22 mm, a thickness of 8 mm, and a height of 48 m.
m, a battery weight of about 19 g and a battery capacity of 610 mAh. To verify the effectiveness of this battery, a lithium ion secondary battery of the same standard was manufactured as a comparative example using a battery can using a conventional clad material.

The comparative example is a battery of an all-cladding material formed with the same outer diameter as the battery can 14 using the same two types of cladding materials as used in the battery can 14. As for the battery weight, the comparative example in which the battery can was formed from the clad material is more advantageous, but the battery of the embodiment of the present invention is easy to process because the processed portion is a single metal in the process such as laser sealing. And high safety such as liquid leakage.
The effectiveness of the battery of the example using was clarified.

Each of the embodiments described above is an example in which the present invention is applied to a cylindrical or prismatic secondary battery. However, the secondary battery swells due to an increase in the internal pressure of the battery due to charging or the like and the pressure resistance of the sealing portion. These were subjected to the most severe conditions, and these were applied. Therefore, it is clear that the present invention may be applied to a primary battery having a more moderate application condition.

In addition, stainless steel can be used as the steel sheet material constituting the battery can. The workability in the DI method is slightly inferior to the SPCE material used in each embodiment, but the pressure resistance and the corrosion resistance can be improved. it can.
SUS304, SUS430 and the like are suitable as stainless steel.

[0066]

As described above, according to the present invention, the battery can is formed in a cylindrical shape with a bottom, and the material other than the peripheral surface of the sealing portion of the battery can has a two-layer structure of a dissimilar metal or alloy. The sealing portion peripheral surface material is made of any one of the two-layer structure materials other than the sealing portion peripheral surface so that the bottom surface thickness / side peripheral surface thickness ratio becomes 1.2 to 5.0. Since the battery can is formed, laser sealing is facilitated, and a reduction in the pressure resistance of the sealing is prevented, and the thickness and weight of the battery can are reduced, thereby improving the volume energy density and the weight energy density of the battery can. Can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of a nickel-metal hydride storage battery according to a first embodiment.

FIG. 2 is a cross-sectional view showing a configuration of a starting material of a battery can.

FIG. 3 is a schematic sectional view showing a configuration of a DI method.

FIG. 4 is a sectional view showing a configuration of a cylindrical battery can.

FIG. 5 is a cross-sectional view showing a configuration of a starting material of a battery can.

FIG. 6 is a sectional view showing a schematic configuration of a lithium ion secondary battery according to a second embodiment.

FIG. 7 is a sectional view showing the configuration of a prismatic battery can.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nickel-metal hydride storage battery 2 Battery can (cylindrical shape) (a) Bottom surface (b) Side peripheral surface (c) Seal peripheral portion peripheral surface 3 Power generation element 4 Sealing plate 5 Aluminum killed steel 6 Pure aluminum material 7 Cup intermediate product 11 Cup intermediate Product (SPCE material) 12 Cup-shaped intermediate product (aluminum material) 13 Lithium ion secondary battery 14 Battery can (square) (a) Bottom surface (b) Side peripheral surface (c) Sealing part peripheral surface 15 Power generation element 16 Sealing cap

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Akira Hashimoto 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference) 5H011 AA03 CC05 CC10 DD03 KK01 KK02

Claims (11)

[Claims] 1. A battery can formed in a cylindrical shape with a bottom,
The material other than the peripheral surface of the sealing portion of the battery can has a two-layer structure of a dissimilar metal or a different alloy, and the peripheral material of the sealing portion is made of any one of two-layer structure materials other than the peripheral surface of the sealing portion,
A battery can, formed so that a bottom surface thickness / side peripheral surface thickness ratio is 1.2 to 5.0. 2. The battery can according to claim 1, wherein one layer of the two-layer structure material is aluminum or an aluminum alloy. 3. The aluminum alloy is 0.5 to 2.5 wt.
3. The battery can according to claim 2, wherein the battery can contains manganese. 4. The battery can according to claim 1, wherein one layer of the two-layer structure material is a steel plate. 5. The battery can according to claim 4, wherein the steel sheet is a carbon steel for cold rolling having a carbon content of 0.1 wt% or less. 6. The battery can according to claim 4, wherein a nickel layer is provided on both sides or one side of the steel sheet material layer. 7. The battery can according to claim 1, wherein the material of the peripheral surface of the sealing portion and the material of the inner surface of the battery can are the same. 8. A battery can formed in a cylindrical shape with a bottom and a two-layer structure of an iron steel plate and aluminum or an aluminum alloy except for a peripheral portion of a sealing portion of the battery can. It is made of any one of the two-layer structure materials other than the peripheral surface, and the bottom surface thickness / side peripheral surface thickness ratio is 1.2 to 5.0.
A battery can characterized by being formed so that 9. A cup-shaped intermediate product formed by drawing a material formed by bonding two layers of different kinds of metal to a portion having a two-layer structure, or by squeezing or drawing and squeezing. The method for producing a battery can according to claim 1. 10. The method according to claim 1, wherein each metal material or alloy material having a two-layer structure is worked into a bottomed cylindrical shape and then fitted, and then subjected to squeezing or drawing and squeezing. Of manufacturing a battery can. 11. A battery comprising the battery can according to claim 1 and a power generation element housed therein.