JP4817724B2 - Plated steel sheet for battery container, battery container using the plated steel sheet for battery container, and battery using the battery container - Google Patents

Description

  The present invention relates to a plated steel sheet for battery containers, a battery container using the plated steel sheet for battery containers, and a battery using the battery container.

  In recent years, portable devices such as audio devices and mobile phones have been used in various fields, and alkaline batteries that are primary batteries, nickel-hydrogen batteries that are secondary batteries, lithium ion batteries, and the like are frequently used as operating power sources. In these batteries, there is a constant demand for higher performance such as higher output and longer life, and the battery container filled with the positive electrode and the negative electrode active material also improves the performance as an important component of the battery. It has been demanded. For example, a surface-treated steel sheet for a battery case in which a nickel-phosphorus alloy layer is formed on the inner surface side of the battery case in order to improve the corrosion resistance against an alkaline solution used in the electrolyte for the purpose of extending the life (Patent Literature) 1) has been proposed.

  In addition, in a battery using a can formed by press drawing and ironing, in order to reduce the internal resistance of the battery, a cold is formed by forming a silver plating layer on the nickel plating layer on the inner surface of the can. Cold-rolled steel sheet is press-drawn and ironed to create fine cracks to form uneven surfaces, increase the contact area with the positive electrode mixture and conductive coating, reduce the internal resistance of the battery, or nickel After a silver plating layer is formed on the plated layer, heat treatment is performed to form a nickel-silver plating layer, the plating crystals are densified to increase the hardness, and the crack spacing is further increased. Thus, a battery can (Patent Document 2) has been proposed in which the contact area with the positive electrode mixture or the conductive coating is further increased to reduce the internal resistance of the battery.

  However, in the surface-treated steel sheet for battery case of Patent Document 1, since the nickel-phosphorus alloy layer directly formed on the steel sheet surface used for the battery container inner surface is hard and brittle, it is formed into a container by drawing or drawing ironing. During processing, the underlying steel may be exposed and the corrosion resistance to the alkaline solution used in the electrolyte may be reduced. Similarly, in the battery can of Patent Document 2, it is difficult to avoid the possibility that the base steel is exposed and the corrosion resistance to the alkaline solution used in the electrolyte is lowered when the press can be squeezed and ironed to generate fine cracks. is there.

International Publication No. WO99 / 03161 JP 2001-325924 A

  In the present invention, a microcrack is generated when the container is molded by drawing or ironing, and the adhesiveness with the positive electrode mixture of the alkaline battery is improved to provide a battery having excellent battery characteristics. It is an object to provide a plated steel sheet for a battery container, a battery container using the plated steel sheet for a battery container, and a battery using the battery container.

In order to achieve the object of the present invention, the plated steel sheet for battery containers of the present invention is an iron-nickel alloy layer, a nickel layer, a nickel-phosphorus alloy layer, in order from the bottom on the steel sheet on the side that is the battery container inner surface of the steel sheet, An iron-nickel alloy layer and a nickel-phosphorus alloy in order from the bottom on the plated steel sheet for battery containers (Claim 1), or a steel sheet on the side of the steel sheet that is the inner surface of the battery container, wherein a silver layer is formed A plated steel sheet for battery containers, wherein a steel layer and a silver layer are formed (Claim 2), or an iron-nickel alloy layer, iron- A nickel-phosphorus alloy layer and a silver layer are formed, and a plated steel sheet for battery containers (Claim 3), or an iron-nickel alloy in order from the bottom on the steel sheet on the side that becomes the battery container inner surface of the steel sheet Layer, iron-nickel-phosphorus alloy , Nickel - phosphorus alloy layer, a battery container for plating steel sheet wherein the silver layer is formed (claim 4).

Moreover, the battery container of this invention is a battery container (Claim 5) formed by shape | molding the plated steel plate for battery containers in any one of the said (Claims 1-4) to a bottomed cylindrical shape.
And the battery of this invention is a battery (Claim 6) using the battery container of said (Claim 5).

The plated steel sheet for battery containers of the present invention is subjected to nickel plating on the side of the steel sheet which will be the battery container inner surface, then nickel-phosphorus alloy plating thereon, and further subjected to diffusion heat treatment after silver plating thereon. To form an iron-nickel alloy layer on the steel sheet, and an iron-nickel-phosphorus alloy layer and / or nickel-phosphorus alloy layer having excellent corrosion resistance against an alkaline solution on the steel plate, and further conductive thereon. When formed into a battery container, a microcrack is generated in the hard phosphorus-containing alloy layer on the inner surface of the battery container, and adheres to the positive electrode mixture of the alkaline battery. As a battery container material with excellent discharge characteristics after long-term storage, combined with improved conductivity due to the formation of a silver layer It can be. In addition, the silver oxide formed on the outermost surface converts the hydrogen gas generated by the electrochemical reaction with the alkaline electrolyte into water, so that the internal pressure of the electric field does not increase and the leakage resistance is improved. Can be increased.

  The contents of the present invention will be described below. As a steel plate used as a substrate for the plated steel plate for battery containers of the present invention, general-purpose low carbon aluminum killed steel (carbon content 0.01 to 0.15 wt%), or non-aging ultra-low carbon added with niobium or titanium. Aluminum killed steel (carbon content less than 0.01% by weight) is used. These steel hot-rolled plates are pickled to remove surface scales, and then cold-rolled and then subjected to electrolytic cleaning, annealing, and temper rolling are used as the substrate (A). Cold rolling and electrolytic cleaning may be followed by plating as a substrate (B) without annealing, followed by annealing for both diffusion heat treatment and softening of the steel sheet.

When using a board | substrate (A), nickel plating is first given to both surfaces of the steel plate which is a board | substrate. The nickel plating is preferably matte plating or semi-gloss plating obtained by plating using a bath containing an organic brightener in a matte plating bath. Bright plating using a bath containing an organic brightener containing a sulfur component is not preferred because heating after plating results in brittleness of the coating due to the sulfur component and a decrease in corrosion resistance. As a plating amount, it is preferable that the side which becomes an outer surface of a battery container is 5-30 g / m < ² >. If it is less than 5 g / m ² , sufficient corrosion resistance cannot be obtained, and if it exceeds 30 g / m ² , the effect of improving corrosion resistance is saturated, which is not economically advantageous. The plating amount on the side that becomes the inner surface of the battery container is preferably 5 to 27 g / m ² . If it is less than 5 g / m ² , the degree of exposure of the steel substrate increases when it is formed into a battery container, resulting in deterioration of battery performance. On the other hand, if it exceeds 27 g / m ² , the effect of improving the battery performance is saturated, which is not economically advantageous.

Next, nickel-phosphorus alloy plating is applied only to one side which is the inner surface of the battery container. Next, silver plating is applied. The nickel-phosphorus alloy plating may be formed using either an electroplating method or an electroless plating method, but in the present invention, it is preferable to use an electroplating method that allows easy bath management and adjustment of the plating amount. . The plating amount is preferably 0.5 to 5 g / m ² as nickel. 0.5. If it is less than g / m < ² >, the depth of the micro crack formed in the surface of a battery container inner surface will become small, and it will become scarce in the improvement effect of adhesiveness with a positive mix. On the other hand, if it exceeds 5 g / m ² , the depth of the microcracks increases, cracks having a depth that penetrates the underlying nickel plating and reaches the steel substrate, and the battery performance deteriorates. Moreover, it is preferable that the phosphorus content of nickel- phosphorus alloy plating measured using a fluorescent X-ray method is 4 to 12%. The phosphorus content can be adjusted by appropriately selecting the concentration of phosphorous acid in the plating bath, the pH of the bath, the current density, and the bath temperature.

Subsequently, silver plating is performed on the nickel-phosphorus alloy plating formed as described above. For the silver plating, either a cyan bath or a non-cyan bath can be used, but a non-toxic non-cyan bath is preferably used from the viewpoint of toxicity. As the amount of plating, it is possible to bring about an excellent effect of improving electrical conductivity with an amount of flash plating, and it is preferably 0.05 to 1.0 g / m ² . 0.05 g / m, sufficient effect of improving the electrical conductivity obtained is less than ^2, the effect of improving the electrical conductivity exceeds 1.0 g / m ² is saturated, it is not economically advantageous.

Thereafter, diffusion heat treatment is performed using a box-type annealing method or a continuous annealing method. In the diffusion heat treatment, during the nickel-phosphorus alloy plating, a phase having a composition of Ni ₃ P is precipitated and hardened by heating, and the nickel plating layer under the nickel-phosphorus alloy plating is recrystallized and softened. Or it implements on the conditions from which one part or all part of nickel plating becomes an iron-nickel diffused layer. That is, it is heated to 450 to 650 ° C., preferably 500 to 600 ° C. in a protective atmosphere. Even if heated at less than 450 ° C., the nickel plating does not recrystallize and therefore does not soften, and an iron-nickel diffusion layer does not form. On the other hand, when heated at a temperature exceeding 650 ° C., the iron-nickel diffusion layer is sufficiently formed, but the nickel-phosphorus alloy plating is softened. When the diffusion heat treatment is performed using the box-type annealing method, it is preferable to heat near 450 to 550 ° C. for 1 to 6 hours, and when the diffusion heat treatment is performed using the continuous annealing method, 1 to 550 to 650 ° C. Heating for ~ 5 minutes is preferred.

  The amount that part or all of the nickel plating is converted into the iron-nickel alloy layer can be appropriately adjusted depending on the nickel plating amount and the heat treatment conditions. Further, the amount that part or all of the nickel-phosphorus alloy plating is converted into the iron-nickel-phosphorus alloy layer can be appropriately adjusted depending on the nickel-phosphorus alloy plating amount and the heat treatment conditions.

  In these diffusion heat treatments, at 450 to 650 ° C., the uppermost silver layer does not have a solubility with the lower nickel layer so that it does not form an alloy with nickel. Since it exists on the outermost surface as a silver oxide layer, excellent electrical conductivity and low contact resistance can be maintained even after heat treatment.

  Alternatively, after nickel plating and then nickel-phosphorus alloy plating, diffusion heat treatment may be performed, and then silver plating may be performed thereon to form a silver layer.

In this way, an iron-nickel alloy layer or a nickel layer is formed on the iron-nickel alloy layer on one side which is the outer surface of the battery container, and the following A is formed on the other side which is the inner surface of the battery container. ) To D), ie, A) iron-nickel alloy layer, nickel layer, nickel-phosphorus alloy layer, silver layer in this order from the steel plate side.
B) Iron-nickel alloy layer, nickel-phosphorus alloy layer, silver layer,
C) Iron-nickel alloy layer, iron-nickel-phosphorus alloy layer, silver layer,
D) A plated steel sheet in which any one of an iron-nickel alloy layer, an iron-nickel-phosphorus alloy layer, a nickel-phosphorus alloy layer, and a silver layer is formed is obtained. This plated steel sheet is temper rolled to obtain a plated steel sheet for battery containers of the present invention. In addition, instead of forming a nickel layer on the iron-nickel alloy layer or the iron-nickel alloy layer on one side that is the outer surface of the battery container of steel plate, the above is applied to the other side that is the inner surface of the battery container. A similar plating layer of any one of A) to D) may be formed.

  After performing any diffusion heat treatment in this manner, temper rolling is performed at a rolling rate of 1.0 to 1.5% in order to prevent the occurrence of stretcher strain. Thus, the plated steel sheet for battery containers of this invention can be obtained.

  The battery container of the present invention is obtained by subjecting the above-described plated steel sheet for a battery container to a drawing process, a drawing ironing process (DI processing method), a drawing stretch processing method (DTR processing method), or a drawing process as a stretching process. It is obtained by forming into a bottomed cylindrical shape using the processing method used in combination. As the cylindrical shape, the bottom surface is a circle, an ellipse, or a polygonal shape such as a rectangle or a square, and is molded into a cylindrical shape with the side wall height appropriately selected according to the application. The battery container thus obtained is filled with a positive electrode mixture, a negative electrode active material, and the like to obtain a battery.

Hereinafter, the present invention will be described in detail with reference to examples.
[Creation of plated steel sheets for battery containers]
As a substrate, cold rolled plates of low carbon aluminum killed steel (I) and extremely low carbon aluminum killed steel (II) whose chemical compositions are shown in Table 1 are used, and the battery container plating is performed through the following steps 1) or 2). A steel plate was created.
1) Cold rolling-> Electrolytic cleaning-> Annealing (box annealing or continuous annealing)-> (tempered rolling)-> nickel plating-> nickel-phosphorus alloy plating-> silver plating-> diffusion heat treatment (box annealing or continuous annealing)-> tempering Rolling 2) Cold rolling → Electrolytic cleaning → Annealing (box annealing or continuous annealing) → → (tempered rolling) nickel plating → nickel-phosphorus alloy plating → diffusion heat treatment (box annealing or continuous annealing) → temper rolling → In the case of low-carbon aluminum killed steel (I), silver plating annealing is soaked at 640-680 ° C. for 8 hours by box annealing, and in the case of extremely low carbon aluminum killed steel (II), it is heated at 780 ° C. for 1 minute by continuous annealing. Carried out.

The nickel plating, nickel-phosphorus alloy plating, and silver plating in the process shown in 1) or 2) above were performed under the following conditions.
<Nickel plating>
Bath composition Nickel sulfate 300g / L
Nickel chloride 40g / L
Boric acid 30g / L
Pit inhibitor (sodium lauryl sulfate) 0.4mL / L
Anode Nickel pellet (filled in titanium basket)
Agitation Air agitation pH 4 to 4.6
Bath temperature 55-60 ° C
Current density 20A / dm ²

<Nickel-phosphorus alloy plating>
Bath composition Nickel sulfate 240g / L
Nickel chloride 40g / L
Boric acid 30g / L
Phosphorous acid 4-12g / L
Anode Nickel pellet (filled in titanium basket)
Stirring Air stirring Bath temperature 40-60 ° C
Current density 4-15A / dm ²

<Silver plating>
Bath composition Silver-containing organic acid salt (Dyne Silver NEC (manufactured by Daiwa Kasei Laboratories))
200g / L
Organic acid (complex salt) (Dyne Silver AGI (manufactured by Daiwa Kasei Laboratories))
500g / L
Organic additive (smoothing agent) (Dyne Silver AGH (manufactured by Daiwa Kasei Laboratories))
25g / L
Anode Silver plate Stirring Circulation of plating bath Bath temperature 35-40 ° C
Current density 1A / dm ²

  As described above, samples (sample numbers 1 to 7) of the plated steel sheets for battery containers shown in Table 2 were prepared. For comparison, a sample not subjected to silver plating (sample number 8), a sample subjected only to nickel plating (sample number 9), and a sample directly subjected to silver plating on the nickel plating (sample number 10) were also prepared.

[Create battery container]
After punching blanks with a diameter of 57 mm from these samples Nos. 1 to 10, the outer surface of the container was formed by ten steps of drawing so that the side on which only the iron-nickel alloy layer and the nickel layer were provided became the outer surface of the container. It was molded into a cylindrical LR6 type battery (AA size battery) container having a height of 4 mm and a height of 49.3 mm.

[Create battery]
Using this battery container, an alkaline manganese battery was prepared as follows. Manganese dioxide and graphite were collected at a ratio of 10: 1, and potassium hydroxide (10 mol) was added and mixed to prepare a positive electrode mixture. Next, this positive electrode mixture was pressed in a mold to form a donut-shaped positive electrode mixture pellet having a predetermined size, and was press-inserted into the battery container. In addition, some battery containers used what applied the coating material which has graphite powder as a main component on the inner surface. Next, the negative electrode plate spot-welded with the negative electrode current collector rod was attached to the battery container. Next, a separator made of vinylon woven cloth is inserted along the inner circumference of the positive electrode mixture pellet press-inserted into the battery container, and the negative electrode gel made of potassium hydroxide saturated with zinc particles and zinc oxide is put into the battery container. Filled in. Further, an insulating gasket was attached to the negative electrode plate and inserted into the battery container, followed by caulking to prepare an alkaline manganese battery.

[Characteristic evaluation]
The characteristics of the batteries prepared using the battery containers prepared from the samples Nos. 1 to 10 as described above were evaluated as follows.

<Short-circuit current>
After leaving the battery at 80 ° C. for 3 days, an ammeter was connected to the battery, a closed circuit was provided, and the current value was measured, which was defined as a short-circuit current. It shows that a characteristic is so favorable that a short circuit current is large.

<Discharge characteristics>
After leaving the battery at 80 ° C. for 3 days, the battery was discharged to a constant current of 1.5 A, and the time until the voltage reached 0.9 V was measured as the discharge time. The longer the discharge time, the better the discharge characteristics.

<Intermittent discharge characteristics>
As an evaluation of intermittent discharge, an operation of discharging at 2A for 0.5 seconds and then discharging at 0.25A at 29.5 seconds was taken as one cycle, and this cycle was repeated to measure the number of cycles until the voltage reached 1.0V. did. It shows that a intermittent discharge characteristic is so favorable that there are many cycles.

<Gas generation>
The battery is partially discharged (3.9Ω, 1.5 hours), then left at 70 ° C. for 2 weeks, then opened with the battery immersed in water, and the gas generated and retained inside the battery is graduated The gas was collected in a burette and the gas generation amount was measured.
These evaluation results are shown in Table 3.

  As shown in Table 3, the plated steel sheet for battery containers of the present invention is a plated steel sheet for battery containers that is not subjected to silver plating, a plated steel sheet for battery containers that is subjected only to nickel plating, and direct silver plating on the nickel plating. Compared to the plated steel sheet for battery containers, it is excellent in all of short circuit current, discharge characteristics, and intermittent discharge characteristics. Moreover, when the graphite paint was applied to the inner surface of the battery container using the plated steel sheet for the battery container of the present invention, the short circuit current, the discharge characteristics, and the intermittent discharge characteristics were further improved.

An iron-nickel alloy layer is formed on the steel plate, and an iron-nickel-phosphorus alloy layer and / or nickel-phosphorus alloy layer having excellent corrosion resistance against an alkaline solution is formed thereon, and further conductively formed thereon. When the plated steel sheet for a battery container of the present invention formed with an excellent silver layer is formed into a battery container, microcracks are generated in the hard phosphorus-containing alloy layer on the inner surface of the battery container, and the positive electrode of the alkaline battery Adhesion with the mixture increases, and combined with improved conductivity by forming a silver layer, it can be suitably applied as a high-performance battery container material with excellent discharge characteristics after long-term storage. it can. In addition, the silver oxide formed on the outermost surface converts the hydrogen gas generated by the electrochemical reaction with the alkaline electrolyte into water, so that the internal pressure of the electric field does not increase and the leakage resistance is improved. Can be increased. In addition, since the battery characteristics are superior to those of conventional containers with graphite paint applied to the inner surface of the container, the step of applying and drying the graphite paint can be omitted, and a high-performance battery can be manufactured at low cost. it can.

Claims (6)

An iron-nickel alloy layer, a nickel layer, a nickel-phosphorus alloy layer, and a silver layer are formed in order from the bottom on a steel plate on the side that is the inner surface of the battery case of the steel plate. An iron-nickel alloy layer, a nickel-phosphorus alloy layer, and a silver layer are formed in order from the bottom on a steel plate that is the inner surface of the battery case of the steel plate. An iron-nickel alloy layer, an iron-nickel-phosphorus alloy layer, and a silver layer are formed in order from the bottom on a steel plate on the side that is the inner surface of the battery case of the steel plate. A battery container comprising an iron-nickel alloy layer, an iron-nickel-phosphorus alloy layer, a nickel-phosphorus alloy layer, and a silver layer formed in order from the bottom on a steel sheet on the side that is the inner surface of the battery container. Plated steel sheet. The battery container formed by shape | molding the plated steel plate for battery containers in any one of Claims 1-4 in a bottomed cylindrical shape. A battery comprising the battery container according to claim 5.