JPH08260191A - Battery case - Google Patents

Abstract

PURPOSE: To provide a battery case by using a material appropriate to improve the formability of the case without deteriorating the resistance of the case to the corrosion of a sealed alkaline soln., to allow the inner face of the case to maintain alkali corrosion resistance and to improve the electric-contact performance of its outer face. CONSTITUTION: The inner face of the case is plated with nickel at 5-40g/m<2> , and the outer face is plated with tin at 2.8-17g/m<2> . Besides, the inner face is plated with nickel at 5-40g/m<2> , the outer face is plated with tin at 2.8-17g/m<2> , and a part of the nickel plating layer forms an tin-nickel alloy layer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to deep drawing workability, DI
The present invention relates to a battery case using a surface-treated steel sheet having excellent formability, and more specifically, to a container for enclosing an alkaline solution, for example, a battery case suitable for battery applications such as an alkali manganese battery and a nickel cadmium battery.

[0002]

2. Description of the Related Art Conventionally, a container for enclosing a strong alkaline liquid such as an alkaline manganese battery or a nickel cadmium battery has been manufactured by pressing a cold rolled steel strip into a battery case and then barrel plating. Alternatively, a method of pressing a nickel-plated steel strip into a battery case has been adopted. However, the barrel plating method has the problems of low productivity, inefficiency, and large variations in plating thickness. Therefore, nickel-plated steel strip for plating cold-rolled steel strip has been widely used instead of the barrel plating method. By the way, the reason why nickel-plated steel strips are often used for battery applications such as alkaline manganese batteries and nickel-cadmium battery containers is as follows. That is, since these batteries mainly use strong alkaline potassium hydroxide etc. as the electrolytic solution, nickel plating is excellent in terms of corrosion resistance to alkaline electrolytic solution, and stable contact when connecting the battery to external terminals. This is because nickel has resistance, and further, spot welding is performed when the components are assembled into a battery, but the nickel-plated steel strip is also excellent in spot weldability. Further, there is a need for nickel plating from the following viewpoint. That is, taking an alkaline manganese battery as an example, when an iron plate is used for the battery case, iron is eluted in the alkaline electrolyte of the battery, and this is deposited on the surface of the zinc particles of the anode to induce self-discharge of zinc. It is supposed to be the cause. Therefore, the nickel-plated steel strip has been suitably used as a battery case material using an alkaline solution as an electrolytic solution.

[0003]

DISCLOSURE OF THE INVENTION In the manufacture of batteries,
As a method of increasing the battery capacity, it has become possible to further reduce the thickness of the material and a DI (drawing and ironing) processing method has also been used (see Japanese Patent Laid-Open No. 60-180058). The DI processing method is considered to be advantageous in terms of pressure resistance because the bottom surface is thicker than the side surface of the battery case. Further, the cylindrical alkaline manganese battery has conventionally been configured as a sealed can with three pieces of a battery case, a positive electrode terminal, and a negative electrode terminal, but from the viewpoint of cost reduction, the positive electrode terminal and the battery case are integrally formed into a convex portion. It is changing to a two-piece type with a battery case and a negative electrode terminal. However, the material properties required for the nickel-plated steel strip are extremely strict in the production of the battery case integrally formed with the convex portion by using the DI processing method. That is, in the DI processing method, the thickness of the side surface of the can is about half the thickness of the bottom surface, and further, two-step step forming is added to finish the battery case of the convex integrated type. The corners are frequently broken during deep drawing of the projection-integrated type, which hinders productivity. Therefore, in combination with the application of a non-aging ultra-low carbon steel that is soft and has excellent deep drawing characteristics, a method of nickel-plating a cold-rolled steel sheet and then heat-treating it has been proposed from the viewpoint of improving the material surface and improving the corrosion resistance. However, these measures cannot sufficiently cope with severe machining conditions, and further improvement in workability is required. In addition, as batteries have been used in various applications in recent years, what has conventionally been sufficiently functioning as the contact resistance of nickel plating has become a problem. That is, the contact load on both electrodes of the battery has come to be in a wide range from a very light load to a high load. Therefore, a more stable battery case having a low electric contact resistance has been demanded. When the electrical contact resistance is high, the contact voltage between the positive or negative electrode terminal and the contact surface on the other side becomes high, and the battery life is shortened due to the influence. in this way,
With the demand for lighter weight and higher capacity of batteries, the required performance of nickel-plated steel strip, which is a material, has become more severe. That is, as described above, the demand for thinning the battery case and the severe processing method have been widely applied, and the problem that the conventional battery case formed of nickel-plated steel sheet cannot follow the progress of the can manufacturing technology. There was a point. Therefore, the present invention provides a battery case molded using a suitable material that does not impair the corrosion resistance of the battery case with respect to the enclosed alkaline liquid and further improves the battery case moldability, and the inner surface of the case is resistant to alkali corrosion. The outer surface of the case has improved electrical contact performance.

[0004]

In order to solve the above problems, the present invention provides a battery case in which the inner surface of a can is nickel-plated or nickel-plated and then tin-plated, and the outer surface of the can is tin-plated. That is, the battery case of the present invention has the following features. [1] The inner surface of the case is plated with nickel at a plating amount of 5 to 40 g / m ² , and the outer surface of the case is plated with tin at a plating amount of 2.8 to 17 g / m ² . [2] The inner surface of the case is nickel-plated with a plating amount of 5 to 40 g / m ² , and the outer surface of the case is tin-plated with a plating amount of 2.8 to 17 g / m ² .
Moreover, a part of the nickel plating layer forms an iron-nickel alloy layer. [3] The inner surface of the case is nickel-plated with a plating amount of 5-40 g / m ² , and the outer surface of the case is nickel-plated with a plating amount of 1-10 g / m ² and a plating amount of 2.8- It is tin-plated with 17 g / m ² . [4] The inner surface of the case is plated with nickel at a plating amount of 5 to 40 g / m ² , and the outer surface of the case is plated with nickel at a plating amount of 1 to 10 g / m ² and a plating amount of 2.8 to It is plated with 17 g / m ² of tin, and part of the nickel-plated layers on both sides forms an iron-nickel alloy layer. [5] The case of the inner surface, the plating quantity 5 to 40 g / m ² of nickel plating has been applied on the outer surface of the case, the plating weight of the nickel plating and the plating of 40 g / m ² exceed 10 g / m ² An amount of 1.7 to 17 g / m ² of tin plating is applied. [6] The case of the inner surface, the plating quantity 5 to 40 g / m ² of nickel plating has been applied on the outer surface of the case, the plating weight of the nickel plating and the plating of 40 g / m ² exceed 10 g / m ² An amount of 1.7 to 17 g / m ² of tin plating is applied, and a part of the nickel plating layers on both sides forms an iron-nickel alloy layer. [7] Deep drawing or D
It is obtained by I molding.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The battery case of the present invention will be described separately for the inner surface side of the case and the outer surface side of the case. (Inside surface of case) In the present invention, the inside surface of the case is plated with nickel. The plating amount is determined as follows (see FIG. 1). FIG. 1 shows the results of measuring the elution amount of iron after a potassium hydroxide solution was placed in a cylindrical squeezer (the case inner surface was nickel-plated) and left for 12 days. Create several kinds of plated steel sheets with different plating amounts, draw to make a cylindrical can with an outer diameter of 13 mm and a height of 49 mm, put a potassium hydroxide solution (concentration: 8 mol) in it, and set the temperature to 65 ° C. The amount of iron eluted into the solution after 12 days was measured. The elution amount of iron was measured by an inductively coupled plasma emission spectroscopic analysis method suitable for trace amount measurement. FIG.
From the results, it can be seen that when the nickel plating amount is less than 5 g / mm ² , the iron elution amount sharply increases and the durability of the battery case deteriorates. On the other hand, even if it exceeds 32 g / m ² , the effect of the nickel plating amount does not remarkably appear, and it is uneconomical. Therefore, the nickel plating amount is preferably in the range of 5 g to 32 g / mm ² . The nickel-plated surface is also preferably dull-finished. The reason is that the self-discharge rate becomes lower because the contact strength with the battery active material (which corresponds to manganese dioxide in the case of alkaline manganese battery) is high and the contact resistance is low.

(Outer surface of case) The reason why the tin plating is on the outer surface of the case is because of the stable electric contact resistance of the tin plating and the excellent processing performance (see FIG. 2). Regarding the electric contact resistance, it is considered that the reason why tin plating is stable is that the electric contact resistance is stabilized because the plating surface layer is soft. When the surface hardness of the cold-rolled steel sheet was tin-plated and nickel-plated, the tin-plated sheet (plating amount: 17 g / m ² ) had a HV of 5 g and a load of 4
5 while nickel plating (adhesion amount 17g / m
² ) is 305 as it is plated, and from the tin-plated surface,
The nickel plating was found to have a hard plating surface layer. Further, the hardness was maintained at 210 even when a heat treatment was carried out after the nickel plating at a heating temperature of 550 ° C. for a soaking time of 6 hours and a softening heat treatment was performed after the nickel plating. Further, nickel plating exhibits superior electrical contact resistance compared to other metals such as iron, but still has higher electrical contact resistance than tin plating.
The reason is that the nickel plating surface layer is oxidized to form NiO having a high electric resistance, and because the nickel plating layer is harder than the tin plating layer as described above, that is, the deformation resistance is high, the contact area is tin plated. This is probably because it is smaller. The result of measuring the actual electrical contact resistance is shown in FIG.

From FIG. 2, the lower the measuring load, the higher the electrical contact resistance, and the lower the electrical contact resistance value as the measuring load increases. It is considered that this is because the contact area increases as the load increases and the oxide film on the surface is destroyed.
However, it can be seen that the electrical contact resistance becomes stable when the amount of deposited tin plating becomes 0.5 g / m ² or more, regardless of the contact load. Therefore, the lower limit of the amount of tin plating deposited is 0.5 g / m ² from the viewpoint of stable electrical contact resistance. Here, the measuring method of the electrical contact resistance was performed as follows. AC 4 terminal method, the contactor is a brass rod tip 1R
The processed surface is plated with gold, the applied current is 10 mmA, and the contact load is 200 g and 100
It was measured under a constant load of 0 g.

Next, another reason for performing tin plating on the outer surface of the case is that it has excellent processing performance even for severe forming processing such as DI processing and convex processing. Since tin is soft and rich in ductility, and recrystallizes even at room temperature, it does not work harden like iron and nickel. Furthermore, since it is a low melting point metal (melting point 232 ° C), it requires severe deep drawing and DI.
If the temperature rises on the contact surface with the press die during processing,
Since the tin-plated layer exhibits a more lubricating effect, it significantly improves the processing performance of the work piece. Especially when considering the punch side and the die side that affect the processing performance, the die side affects the processing performance more. This means that the present invention is single-sided tin plating,
Moreover, since the molding is performed outside the battery parts such as the battery case, the side surface of the die and the tin-plated surface come into contact with each other, which is convenient.
The lower limit of the tin plating amount from the viewpoint of workability is determined by the number of cracks in the case. That is, when the amount of tin plating is small, a plate having a large blank diameter cannot be drawn, and cracks occur during case molding. Fig. 3 shows the results of investigation of workability by changing the tin plating amount. From the results shown in FIG. 3, when the tin plating amount was 1.7 g / m ² or more, good molding could be performed, but when the tin plating amount was less than 1.7 g / m ² , cracking occurred in the case. The case was processed and formed as follows. Punch diameter 57.0 mm, die diameter 5
The cup was drawn with a blank diameter of 120 mm at 7.64 mm, a punch and die radius of 2 mm, and a wrinkle presser of 500 kg. On the other hand, even if the tin plating amount exceeds 17 g / m ² , there is no technical improvement, and the upper limit is 17 g from the economical point of view.
/ M ² . Therefore, the tin plating amount is 1.7 to 17 g / m in consideration of the electric contact resistance, drawability and economy.
² is the proper range. Note that tin plating includes a reflow treatment (tin melting treatment) after plating and a non-reflow method as it is, but either method may be used in the present invention. However, more preferably, the method of performing temper rolling after the no-reflow treatment is more preferable. The reason is,
This is because the retaining property of the lubricating oil on the plating surface during press working is superior to that in the case of the reflow treatment in which the surface of the tin plating layer is smoother.

(Invention of Claims 3 to 6) From the viewpoint of further improving the corrosion resistance of the outer surface of the case, it is more preferable that nickel plating is applied as an undercoating treatment before tin plating. In this case, nickel is used. coating weight of plating and when it is 1 to 10 g / m ^2, which may exceed 10 g / m ² and 40 g / m ² or less. The reason is that if the plating amount of nickel plating is 1 to 10 g / m ² , sufficient corrosion resistance cannot be ensured, and it is necessary to supplement with tin plating. On the other hand, the amount of nickel plating is 10 g /
If it exceeds m ² , corrosion resistance can be secured by nickel plating, and the tin plating amount can be reduced. Therefore, when nickel plating having a plating amount of 1 to 10 g / m ² is applied, the tin plating amount is 2.8 to
It must be tin-plated at 17 g / m ² . Further, when the coating weight is subjected to a nickel plating 40 g / m ² exceed 10 g / m ^2, the tin plating amount 1.
It may be 7 to 17 g / m ² . The basis for this was to carry out a salt spray test to investigate the corrosion resistance (shown in FIG. 4). Area A (claims 3 and 4) and area B (claim 5) of FIG.
In and 6), sufficient corrosion resistance was obtained, but in area C, the corrosion resistance was poor, and in area D, the workability was not sufficient.

Next, the method for producing the surface-treated steel sheet for producing the battery case of the present invention will be described in detail. (Steel plate) As a plating original plate, low carbon aluminum killed steel is usually used. Further, cold-rolled steel strips made of non-aging ultra-low carbon steel (carbon content: 0.003% or less) to which niobium and titanium are added are also used. Usually, after cold rolling, electrolytic cleaning,
The annealed and temper-rolled steel strip is used as a plating original plate, but the cold-rolled steel plate may be used as it is as a nickel plating original plate. In this case, after cold rolling, nickel plating is performed, and subsequently, a step of recrystallizing and annealing the steel substrate and a step of thermally diffusing the nickel plating layer are simultaneously performed.

(Nickel Plating) The above plating original plate is subjected to alkaline electrolytic degreasing, water washing, sulfuric acid or hydrochloric acid pickling (electrolysis or dipping), and water washing pretreatment, and then nickel plating. In the present invention, the nickel plating bath may be any known plating bath such as a Watts bath, a sulfamic acid bath, or a chloride bath. Furthermore, the types of nickel plating include matte plating, semi-gloss plating and bright plating,
Matte or semi-bright plating other than bright plating to which a sulfur-containing organic substance is added is preferably applied in the present invention. This is because in the case of bright plating, since the plating layer is hard, more surface cracks occur during processing to impair the corrosion resistance, and when heat treatment is performed after nickel plating, the plating layer becomes brittle and deteriorates the corrosion resistance because it contains sulfur.

(Heat Treatment) Although the effect of the present invention can be obtained even with nickel plating as it is, a method of heat treatment after nickel plating is also suitably used as a method of further improving corrosion resistance. That is, the heat treatment after nickel plating softens the nickel plating layer and reduces the amount of cracks generated in the plating layer during processing. As heat treatment conditions, a heating temperature of 450 to 850 in a non-oxidizing atmosphere gas is used.
The treatment is performed at a temperature of 30 ° C. for 30 seconds to 15 hours. As a method for heat-treating a steel strip, there are a box-type annealing method and a continuous annealing method. In the present invention, either method may be used, and in the box-type annealing method, (450 to 650) ° C. × (5 to 15)
In the continuous annealing method, the heat treatment condition of high temperature, short time, that is, (600 to 850) ° C. × (30 seconds to 5 minutes) is preferable.

(Tin Plating) After nickel plating, subsequently, tin plating is applied to the outer surface of the case. The tin deposition amount varies depending on whether the nickel plating applied prior to the tin plating is applied to the base or not, the specified range of the tin plating. The bath composition includes an acidic bath and an alkaline bath which are usually used, but in the present invention, a stannous sulfate bath or a phenol sulfonic acid bath is used. Note that the tin plating method used for can materials and the like is generally manufactured by steps of degreasing, pickling, tin plating, reflow (tin melting treatment), and chemical treatment. A similar method applies. However, under more severe processing conditions such as DI processing, it is preferable to use no reflow (without tin melting treatment), which has good wax lubricity retention.

(Quench rolling) As a method of making the surface more glossy without impairing the processing performance, a method of temper rolling after tin plating is also used. In this method, lightly rolling is performed by a bright work roll with a rolling reduction of 2 to 3% or less without performing tin melting treatment after tin plating. By this method, the dull whitish tin-plated layer without tin melting and the nickel-plated layer exhibiting a dull metallic luster have a glossy and beautiful surface appearance. Further, if it is rolled using a work roll that has been subjected to finish polishing, it is possible to obtain a clean silver-white surface appearance having a metallic luster. When the steel strip is warped due to different types of plating on the front and back sides during temper rolling and the surface friction coefficient is different, the warping can be corrected by passing it through a leveler device after temper rolling.

[0016]

The present invention will be described in more detail with reference to the following examples. A cold-rolled and annealed low-carbon aluminum killed steel plate having a plate thickness of 0.25 mm was used as a plating original plate. The chemical composition of steel is as follows (% by weight). C: 0.04%, Mn: 0.21%, Si: 0.01
%, P: 0.013%, S: 0.010%, Al: 0.
064%, N: 0.0038% The above steel sheet was subjected to alkaline electrolytic degreasing (caustic soda: 30 g /
1, anodic treatment: 5 A / dm ² × 10 seconds, cathodic treatment: 5 A
/ Dm ² × 10 seconds, bath temperature: 70 ° C., sulfuric acid pickling (sulfuric acid:
50 g / l, bath temperature: 30 ° C., 20 seconds immersion)
Nickel plating was performed under the following conditions. Bath composition: Nickel sulfate 320 g / l Nickel chloride 40 g / l Boric acid 30 g / l Sodium lauryl sulfate 0.5 g / l Bath temperature: 55 ± 2 ° C. pH: 4.1-4.6 Stirring: Air stirring Current Density: 10 A / dm ² Anode: Nickel pellets (titanium basket filled with nickel pellets) Matte nickel plating is performed on one side and both sides under the above conditions, and nickel plating is performed by varying the electrolysis time under the above conditions. The thickness was changed. In the case of heat treatment after nickel plating, hydrogen: 6.5%, balance: nitrogen gas, dew point: -40 [deg.] C. protective gas was used, soaking temperature: 550 [deg.] C., soaking time: 6 hours. . Subsequent to nickel plating, tin plating was performed using the following stannous sulfate plating bath. Bath composition: Stannous sulfate 30 g / l (S ++) Phenolsulfonic acid 60 g / l Ethoxylated α-naphthol 5 g / l Bath temperature: 50 ± 2 ° C Current density: 20 A / dm ² Anode: Tin plate plating Was changed by changing the electrolysis time to change the adhesion amount, and the steel strip was heated to 270 ° C. by resistance heating and molten tin was applied to impart gloss. Furthermore, in order to suppress the yellowing due to the oxide film growth of the tin plating layer, the chemical treatment applied to the production of ordinary tin plates was performed. Treatment bath: sodium dichromate 30 g / l Bath temperature: 45 ° C. Cathodic electrolysis: 5 A / dm ² × 5 seconds A sample was prepared under the above conditions. Using each sample, the salt spray test, the amount of iron elution from alkaline solution, and the electrical contact resistance were measured. The salt spray test is based on JIS Z-2371, and shows the results of a spray time of 2 hours. The corrosion resistance was evaluated by a right-angled bending test piece (○: good, ×: inferior). From the results in Table 1, Examples 1 to 13, which are within the scope of the present invention, showed extremely good results in all of the salt spray test, the amount of alkali solution iron elution, the electrical contact resistance, and the workability. On the other hand, Comparative Examples 14 to 19 were out of the scope of the present invention, and thus no good results were obtained.

[0017]

[Table 1]

[0018]

The battery case of the present invention has a deep drawing method D
It can be easily manufactured by the I molding method, and is suitable for a container for enclosing an alkaline solution, for example, a battery case such as an alkaline manganese battery or a nickel cadmium battery. That is, the corrosion resistance of the battery case against the enclosed alkaline solution is not impaired, and moreover, the battery case is easily molded. Furthermore, the inner surface of the case retains alkali corrosion resistance, and the outer surface of the case can improve electrical contact performance.

[Brief description of drawings]

FIG. 1 shows the measurement results of the iron elution amount when the nickel plating amount was changed.

FIG. 2 shows the measurement results of electrical contact resistance when the tin plating amount was changed.

FIG. 3 shows the number of cracks generated during case molding when the tin plating amount was changed.

FIG. 4 is an explanatory view of the relationship between the plating amount on the inner surface of the case.

Claims (7)

[Claims] 1. The plating amount on the inner surface of the case is 5 to 40 g.
/ M ² nickel plating is applied, and the battery case is plated with tin on the outer surface of the case with a plating amount of 2.8 to 17 g / m ² . 2. The plating amount on the inner surface of the case is 5 to 40 g.
/ M ² nickel plating is applied, the outer surface of the case is plated with tin at a plating amount of 2.8 to 17 g / m ² , and a part of the nickel plating layer is an iron-nickel alloy layer. Forming a battery case. 3. The plating amount on the inner surface of the case is 5 to 40 g.
/ M of which the nickel-plated ^2, the outer surface of the case, the battery case tin plating coating weight 1 to 10 g / m ² of the nickel plating and the plating amount 2.8～17G / m ² is applied . 4. The plating amount on the inner surface of the case is 5 to 40 g.
/ M ² of nickel plating is applied, the outer surface of the case is plated with 1 to 10 g / m ² of nickel plating and 2.8 to 17 g / m ² of tin plating, and A battery case in which a part of the nickel plating layers on both surfaces forms an iron-nickel alloy layer. 5. The plating amount on the inner surface of the case is 5 to 40 g.
/ M of which the nickel-plated ^2, the outer surface of the case, the plating weight of the tin plating facilities of 10 g / m ^2, greater 40 g / m ² of the nickel plating and the plating amount 1.7～17G / m ² Battery case. 6. The plating amount on the inner surface of the case is 5 to 40 g.
/ M of which the nickel-plated ^2, the outer surface of the case, the plating weight of the tin plating facilities of 10 g / m ^2, greater 40 g / m ² of the nickel plating and the plating amount 1.7～17G / m ² And a part of the nickel plating layers on the both surfaces forms an iron-nickel alloy layer. 7. The battery case according to any one of claims 1 to 6, which is obtained by deep drawing or DI molding a steel sheet which has been surface-treated in advance.