JP2007051324A - Plated steel plate for battery case, battery case using the steel plate for battery case and battery using the battery case - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plated steel plate for a battery case which is capable of attaining high efficiency discharge characteristic by securing sufficient adhesiveness of the inner surface of the battery case to a positive electrode mixture to prevent the increase of contact resistance even after the long term preservation of the battery and improving conductivity in an alkali electrolyte. <P>SOLUTION: The plated steel plate is obtained by plating nickel on the surface of a steel plate to become an inner surface of the battery case and heat-treating under a non-oxidation atmosphere and after that, plating a nickel-molybdenum alloy or a nickel-cobalt molybdenum alloy or by plating nickel and successively plating the nickel molybdenum alloy or the nickel-cobalt-molybdenum alloy and after that, heat-treating under the non-oxidation atmosphere. The treated steel plate is formed to be applied for the battery case. <P>COPYRIGHT: (C)2007,JPO&INPIT

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, with the development of portable AV equipment and mobile phones such as digital cameras, CD players, MD players, liquid crystal televisions, game machines, etc., alkaline batteries as primary batteries and nickel metal hydride batteries as secondary batteries as heavy load operating power sources Lithium ion batteries are often used. These batteries are required to have higher performance such as higher output and longer life, and battery containers filled with positive and negative electrode active materials are also required to improve performance as important components of the battery. Yes. Conventionally, as these battery container materials, in order to make it possible to maintain corrosion resistance against a strong alkaline electrolyte and low contact resistance at the interface between the inner surface of the battery container and the positive electrode mixture, nickel plating is applied to the cold-rolled steel sheet in advance. A formed nickel-plated steel sheet is formed into a battery container, or a cold-rolled steel sheet is formed into a battery container, and then the inner and outer surfaces of the battery container are nickel-plated by barrel plating. In addition, for nickel-plated steel sheets, in order to improve the adhesion between the nickel-plated layer and the steel substrate, and to suppress the exposure of iron during the forming process, heat treatment is performed after the nickel plating, and iron is interposed between the steel substrate and the nickel-plated layer. -A method of thermal diffusion treatment provided with a nickel alloy layer (diffusion layer) has been proposed (see, for example, Patent Document 1). In addition, the present inventors use a steel plate in which a nickel-tin alloy layer is formed on a nickel layer or an iron-nickel alloy layer (diffusion layer), thereby causing fine cracks when forming the battery container. And forming a concavo-convex surface on the inner surface of the battery container to increase the contact area with the positive electrode mixture or the conductive coating to reduce the internal resistance of the battery (for example, see Patent Document 2), A method for improving the discharge performance by reducing the contact resistance by coating a cobalt compound has also been proposed (see, for example, Patent Document 3).

  However, in the method according to Patent Document 1, it is difficult to sufficiently reduce the contact resistance due to the formation of a passive film on the nickel layer in the alkaline electrolyte. It is difficult to adequately cope with battery applications that require (high-rate characteristics). Moreover, about the technique of patent document 2, press processing, such as a drawing process and a drawing ironing process, is performed by forming a hard layer like the nickel-tin alloy layer formed in the steel plate surface used for a battery container inner surface. It has the feature that excellent battery performance is obtained by generating minute cracks when molding into a container and enhancing the adhesion with the positive electrode mixture of the alkaline battery, but the outermost surface of the nickel-tin alloy layer is It is covered with a passive film in an alkaline electrolyte, increasing the contact resistance and increasing the internal resistance of the battery. For this reason, there exists a fault which cannot fully exhibit the outstanding discharge performance obtained by the adhesive improvement with the positive mix resulting from these alloy layer formation. In addition, in the method of coating a cobalt compound obtained by applying cobalt plating on a cobalt or nickel layer of Patent Document 3 and then heat-treating, although there is a certain effect in improving the conductivity of cobalt, In this case, the contact with the positive electrode mixture or the conductive agent applied to the inner surface of the battery container is loosened and the contact resistance is increased, and it is difficult to sufficiently cope with battery applications requiring high-rate discharge performance after battery storage.

Prior art document information relating to the present application includes the following.
Japanese Patent No. 2810257 Japanese Patent No. 2877957 Japanese Patent Publication No. 07-070320

   In the present invention, sufficient adhesion between the inner surface of the battery container and the positive electrode mixture is obtained even after long-term battery storage, so that contact resistance does not increase and conductivity in an alkaline electrolyte is improved. Accordingly, an object of the present invention is to provide a plated steel sheet for battery containers that can obtain high rate discharge characteristics.

In order to achieve the object of the present invention, the plated steel sheet for battery containers of the present invention is characterized in that an alloy layer containing nickel layer and molybdenum is formed from the bottom on the steel sheet on the side that becomes the battery container inner surface of the steel sheet. An alloy layer containing an iron-nickel alloy layer, a nickel layer, and molybdenum is formed in this order from the bottom on the plated steel sheet for battery containers (Claim 1), or on the steel sheet on the battery container inner surface side. An iron-nickel alloy layer and an alloy layer containing molybdenum are formed in this order from the bottom on the plated steel plate for battery containers (Claim 2), or on the steel sheet on the battery container inner surface side. It is a plated steel sheet for battery containers (Claim 3),
In the plated steel sheet for battery containers according to any one of the above (claims 1 to 3), the alloy layer containing molybdenum is a nickel-molybdenum alloy layer (claim 4), or the alloy layer containing molybdenum is nickel- It is a cobalt-molybdenum alloy layer (Claim 5).
Moreover, the battery container of this invention is a battery container (Claim 6) formed by shape | molding the plated steel plate for battery containers in any one of the said (Claims 1-5) in a bottomed cylindrical shape.
The battery of the present invention is a battery (Claim 7) using the battery container of the above (Claim 6).

  The plated steel sheet for battery containers according to the present invention is obtained by applying nickel plating to the inner surface of the steel sheet or after heat-treating in a non-oxidizing atmosphere after nickel plating, then nickel-molybdenum alloy plating or nickel-cobalt- It is obtained by performing molybdenum alloy plating or nickel plating, followed by nickel-molybdenum alloy plating or nickel-cobalt-molybdenum alloy plating, and then heat-treating in a non-oxidizing atmosphere. When the plated steel sheet for the battery container thus obtained is formed into a battery container, the inner surface of the battery container is formed with fine cracks on the hard and brittle molybdenum-containing alloy, and the surface becomes uneven. Adhesiveness with the agent is improved, low contact resistance is reduced, and excellent battery characteristics are obtained. Further, even if a crack generated in an alloy containing molybdenum reaches the steel base, since molybdenum is baser than iron in an alkaline aqueous solution, molybdenum is sacrificed and dissolved to suppress dissolution of the steel base. There is no adverse effect on the battery performance or gas generation due to dissolution of molybdenum, and gas generation due to dissolution of the steel substrate can be suppressed. In addition, when nickel-cobalt-molybdenum alloy plating is applied, excellent conductivity in the alkaline electrolyte can be maintained due to the presence of cobalt contained in the alloy. Can be covered. Therefore, the plated steel sheet for battery containers of the present invention is formed into a battery container, and a battery using this battery container can obtain a high rate of discharge characteristics.

  The contents of the present invention will be described below. As a steel plate used as the substrate of the plated steel plate for battery containers of the present invention, low carbon aluminum killed steel for drawing (carbon content 0.01 to 0.15% by weight), or deep drawing for adding niobium or titanium. Non-aging ultra-low carbon aluminum killed steel (carbon content less than 0.01% by weight) is used. These steel hot-rolled plates are pickled to remove surface scales, then cold-rolled by a conventional method, and then subjected to electrolytic cleaning, annealing, and temper rolling as a substrate. Alternatively, an unannealed material after cold rolling and then electrolytically cleaning can be used as a substrate.

First, the matte nickel plating is performed on both surfaces of the steel plate to be the plating substrate, or the semibright nickel plating is performed using a plating bath in which an organic additive is added to a watt bath. The adhesion amount of nickel plating is preferably ² g / m ² or more. If it is less than 2 g / m ² , pinholes are likely to occur, and the steel substrate will be exposed excessively due to wrinkles generated when forming into a battery container, increasing the amount of iron ions dissolved in the alkaline electrolyte. Then, the dissolved iron ions may migrate to the negative electrode zinc and increase gas generation due to an electrochemical reaction with zinc. The upper limit of the nickel plating adhesion amount can be appropriately determined depending on economy, but is preferably 25 g / m ² or less.

  After nickel plating as described above, nickel-molybdenum alloy plating or nickel-cobalt-molybdenum alloy plating is applied. Or after giving nickel plating, after giving the heat processing (diffusion heat treatment) for alloying the iron and nickel layer of a steel base, any one of these alloy plating is given. When heat treatment is performed, a box-type annealing method or a continuous annealing method is performed in a non-oxidizing protective gas atmosphere. In the case of the box-type annealing method, it is preferable to set the heating temperature to 450 to 650 ° C. and the heating time to 1 to 6 hours. When using the continuous annealing method, it is preferable that the heating temperature is 600 to 800 ° C. and the heating time is 10 seconds to 5 minutes. By heat-treating under these conditions, all or part of the nickel in the nickel plating layer is thermally diffused and alloyed. In addition, after the cold-rolled unannealed material is nickel-plated and then subjected to a heat treatment using a continuous annealing method, the unannealed material can be annealed and diffused by a single heat treatment. After performing these heat treatments, temper rolling is performed at a rolling rate of about 0.5 to 2%, and adjustment of mechanical properties (preventing the occurrence of stretcher strain) and appropriate surface roughness are imparted. preferable.

After nickel plating as described above or after nickel plating and then heat treatment, nickel-molybdenum alloy plating or nickel-cobalt-molybdenum alloy plating is applied. As the nickel-molybdenum alloy plating bath, a known plating bath made of a complexing agent such as nickel sulfate, alkali metal molybdate or ammonium molybdate, and an alkali salt of an organic acid is preferably used. The amount of nickel-molybdenum alloy plating is preferably in the range of 0.5 to 5 g / m ² . If it is less than 0.5 g / m ² , the crack depth generated in the hard nickel-molybdenum alloy layer is small when forming into a battery container, and sufficient adhesion with the positive electrode mixture to be filled cannot be obtained. On the other hand, if it exceeds 5 g / m ² , deep cracks occur in the nickel-molybdenum alloy layer and reach the steel substrate, and the steel substrate comes into contact with the alkaline electrolyte and dissolves, thereby increasing the risk of generating gas.

  The molybdenum content (Mo × 100 / (Ni + Mo)) in the nickel-molybdenum alloy film is preferably in the range of 5 to 30%. If the molybdenum content is less than 5%, the hardness of the nickel-molybdenum alloy film is small, the density of cracks generated when forming into a battery container is small, and sufficient adhesion with the positive electrode mixture to be filled cannot be obtained. . It is difficult to adjust the plating bath and electrolysis conditions so that the molybdenum content exceeds 30%.

As the nickel-cobalt-molybdenum alloy plating bath, a bath obtained by adding cobalt sulfate to the above nickel-molybdenum alloy plating bath is used. The amount of nickel-cobalt-molybdenum alloy plating is preferably in the range of 0.5 to 5 g / m ² for the same reason as in the case of nickel-molybdenum alloy plating. The molybdenum content (Mo × 100 / (Ni + Co + Mo)) and the cobalt content (Co × 100 / (Ni + Co + Mo)) in the nickel-cobalt-molybdenum alloy coating are preferably in the range of 5 to 30%. The preferable range of the molybdenum content is the same as that of the nickel-molybdenum alloy film. When the cobalt content is less than 5%, the effect of suppressing the decrease in conductivity due to cobalt when the battery is stored for a long time is poor. It is difficult to adjust the plating bath and electrolysis conditions so that the cobalt content exceeds 30%.

  In the present invention, the steel plate annealed after cold rolling, or the steel plate not annealed after cold rolling was subjected to nickel plating, and then the above-described nickel-molybdenum alloy plating or nickel-cobalt-molybdenum alloy plating was performed. A heat treatment (diffusion heat treatment) may be performed later. When heat treatment is performed on a plated steel sheet that has been plated on an annealed steel sheet using a box-type annealing method, the steel base is heated at a temperature of less than 700 ° C. so that the recrystallized structure of the steel substrate is not coarsened by the second heat treatment It is preferable. When heat treatment is applied to a plated steel sheet obtained by plating an unannealed steel sheet of low-carbon aluminum killed steel, a continuous annealing method is used to heat the steel substrate under conditions of a heating temperature of 600 to 700 ° C. and an overheating time of 10 seconds to 3 minutes. The recrystallization annealing and the diffusion heat treatment to the steel substrate of the plating layer can be performed simultaneously by one heat treatment. Similarly, when heat treatment is performed on a plated steel sheet obtained by plating an unannealed steel sheet of ultra-low carbon aluminum killed steel, the heating temperature is 750 to 800 ° C. and the heating time is 10 seconds to 3 minutes using the continuous annealing method. Thus, the recrystallization annealing of the steel substrate and the diffusion heat treatment of the plating layer to the steel substrate can be performed simultaneously by one heat treatment. After performing these heat treatments, temper rolling is performed at a rolling rate of about 0.5 to 2%, and adjustment of mechanical properties (preventing the occurrence of stretcher strain) and appropriate surface roughness are imparted. preferable.

  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 the plating substrate, hot-rolled low carbon aluminum killed steel (I) or extremely low carbon aluminum killed steel (II) whose chemical composition is shown in Table 1 was used.

After hot rolling plate of the above steel type I or II, cold rolling and electrolytic cleaning by a conventional method to obtain a cold rolled plate having a plate thickness of 0.25 mm, about a part of steel type I, Heat treatment was performed for 8 hours at a soaking temperature of 640 to 680 ° C. using a box annealing method. In addition, for the other part of steel type I, after the following plating was performed on the unannealed plate after electrolytic cleaning, a box-type annealing method was used, and a heating time of 8 hours at a metal heating temperature of 500 ° C or a continuous annealing method was performed. A heat treatment was performed at a soaking temperature of 650 ° C. for 2 minutes. For Steel Type II, after cold rolling and electrolytic cleaning, the following plating was performed, followed by heat treatment at a soaking temperature of 780 ° C. for 2 minutes using a continuous annealing method. Using the plated cold-rolled steel sheet prepared as described above, a plated steel sheet for battery containers was prepared through the steps shown in the following a) to n).
B) Low carbon aluminum killed steel (I) → Cold rolling → Electrolytic cleaning → Annealing (box-type annealing furnace) → Temper rolling → Nickel plating (inside and outside) → Nickel-molybdenum alloy plating (inside)
B) Low-carbon aluminum killed steel (I) → cold rolling → electrolytic cleaning → annealing (box annealing furnace) → temper rolling → nickel plating (inside and outside) → nickel-cobalt-molybdenum alloy plating (inside)
C) Low carbon aluminum killed steel (I) → Cold rolling → Electrolytic cleaning → Nickel plating (inside and outside) → Heat treatment (box annealing furnace) → Temper rolling → Nickel-molybdenum alloy plating (inside)
D) Low carbon aluminum killed steel (I) → Cold rolling → Electrolytic cleaning → Nickel plating (inside and outside) → Heat treatment (box annealing furnace) → Temper rolling → Nickel-cobalt-molybdenum alloy plating (inside)
E) Extremely low carbon aluminum killed steel (II) → Cold rolling → Electrolytic cleaning → Nickel plating (inside and outside) → Nickel-molybdenum alloy plating (inside) → Heat treatment (continuous annealing furnace) → Temper rolling Low carbon aluminum killed steel (II) → Cold rolling → Electrolytic cleaning → Nickel plating (inside and outside) → Nickel-cobalt-molybdenum alloy plating (inside) → Heat treatment (continuous annealing furnace) → Temper rolling Aluminum killed steel (I) → Cold rolling → Electrolytic cleaning → Nickel plating (inner and outer surfaces) → Heat treatment (continuous annealing furnace) → Nickel-molybdenum alloy plating (inner surface side) → Tempered rolling h) Low carbon aluminum killed steel (I ) → Cold rolling → Electrolytic cleaning → Nickel plating (inner and outer side) → Heat treatment (continuous annealing furnace) → Nickel-cobalt-molybdenum alloy plating (inner side) → temper rolling Steel (I) → Cold rolling → Electrolytic cleaning → Annealing (box-type annealing furnace) → Temper rolling → Nickel plating (inner and outer surfaces)
N) Extremely low carbon aluminum killed steel (II) → cold rolling → electrolytic cleaning → nickel plating (inner and outer surface side) → heat treatment (continuous annealing method) → temper rolling It carried out on the conditions shown below.

<Nickel plating>
Bath composition Nickel sulfate 300g / L
Nickel chloride 35g / L
Boric acid 40g / L
Pit inhibitor (sodium lauryl sulfate) 0.4mL / L
Anode Nickel Pellets (Titanium basket filled with S pellets from INCO Corporation and equipped with polypropylene anode bag)
Stirring air stirring
pH 4.0-4.6
Bath temperature 55-60 ° C
Current density 15A / dm ²

<Nickel-molybdenum alloy plating>
Bath composition Nickel sulfate 80g / L
Sodium molybdate 50g / L
Sodium citrate 90g / L
Boric acid 10g / L
Anode Nickel Pellets (Titanium basket filled with S pellets from INCO Corporation and equipped with polypropylene anode bag)
Stirring air stirring
pH 2.5-3.0
Bath temperature 45-50 ° C
Current density 5-15 A / dm ²

<Nickel-cobalt-molybdenum alloy plating>
Bath composition Nickel sulfate 80g / L
Cobalt sulfate 15g / L
Sodium molybdate 50g / L
Sodium citrate 90g / L
Boric acid 10g / L
Anode Nickel Pellets (Titanium basket filled with S pellets from INCO Corporation and equipped with polypropylene anode bag)
Stirring air stirring
pH 2.5-3.0
Bath temperature 45-50 ° C
Current density 5-15 A / dm ²

  After performing the above plating and then heat treatment, temper rolling was performed at a rolling rate of 1.2%, and samples of the plated steel sheets for battery containers (sample numbers 1 to 10) shown in Table 2 were prepared.

[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. Next, a conductive material containing graphite powder as a main ingredient was applied to the inner surface of the battery container, and the positive electrode mixture pellet prepared earlier was press-inserted. 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>
As an evaluation of heavy load continuous discharge, after leaving the battery at 80 ° C. for 3 days, the produced battery was discharged to a constant current of 1.5 A, and the time until the final voltage of 0.9 V was reached was measured as the discharge time. . The longer the discharge time, the better the discharge characteristics.

<Intermittent discharge characteristics>
As an evaluation of the heavy load inter-single discharge, an operation of discharging at 2A for 0.5 seconds and then discharging at 0.25A at 29.5 seconds is one cycle, and intermittent discharge is repeated until the voltage reaches 1.0V throughout. The number of cycles was measured. The larger the number of cycles, the better the intercussion discharge characteristics. These evaluation results are shown in Table 3.

  As shown in Table 3, after nickel plating is applied to the inner surface of the battery container, or after nickel plating and then heat treatment, nickel-molybdenum alloy plating or nickel-cobalt-molybdenum alloy plating is formed thereon. Or nickel plating, followed by nickel-molybdenum alloy plating or nickel-cobalt-molybdenum alloy plating, followed by heat treatment, and formed into a battery container using the plated steel sheet for battery containers of the present invention. Compared to the case of using a plated steel plate for battery containers without nickel-molybdenum alloy plating or nickel-cobalt-molybdenum alloy plating, short-circuit current after storage, heavy load continuous discharge characteristics, heavy load It can be seen that all of the discharge characteristics are improved.

After nickel plating is applied to the battery vessel inner surface of the steel sheet, or after heat treatment in a non-oxidizing atmosphere after nickel plating, nickel-molybdenum alloy plating or nickel-cobalt-molybdenum alloy plating is applied, or nickel After plating, the nickel-molybdenum alloy plating or nickel-cobalt-molybdenum alloy plating is subsequently applied, and then the plated steel sheet for battery containers of the present invention obtained by heat treatment in a non-oxidizing atmosphere is used as the battery container. When molded, the hard and brittle molybdenum alloy produced on the inner surface of the battery container generates fine cracks and the surface becomes uneven, thereby improving the adhesion with the positive electrode mixture and reducing the low contact resistance. Battery characteristics can be obtained. In addition, even if cracks in the molybdenum alloy reach the steel base, molybdenum is baser than iron in an aqueous alkaline solution. Therefore, molybdenum sacrificially dissolves and suppresses dissolution of the steel base. There is no adverse effect on the battery performance or gas generation due to dissolution of the steel, and a large amount of gas generation due to dissolution of the steel substrate can be suppressed. Moreover, since the electroconductivity excellent in alkaline electrolyte can be hold | maintained by presence of cobalt, the electroconductivity by the passive state film | membrane of nickel can be covered. Therefore, the plated steel sheet for battery containers of the present invention is formed into a battery container, and a battery using this battery container can obtain a high rate of discharge characteristics.

Claims (7)

A plated steel sheet for a battery container, wherein a nickel layer and an alloy layer containing molybdenum are formed from the bottom on a steel sheet on the side that is to be the battery container inner surface of the steel sheet. A plated steel sheet for a battery container, wherein an iron-nickel alloy layer, a nickel layer, and an alloy layer containing molybdenum are formed in order from the bottom on a steel sheet on the side that is to be the battery container inner surface of the steel sheet. A plated steel sheet for battery containers, wherein an iron-nickel alloy layer and an alloy layer containing molybdenum are formed in order from the bottom on a steel sheet on the side of the steel container that is to be the inner surface of the battery container. The plated steel sheet for battery containers according to claim 1, wherein the alloy layer containing molybdenum is a nickel-molybdenum alloy layer. The plated steel sheet for battery containers according to claim 1, wherein the alloy layer containing molybdenum is a nickel-cobalt-molybdenum alloy layer. The battery container formed by shape | molding the plated steel plate for battery containers of any one of Claims 1-5 in a bottomed cylindrical shape. A battery comprising the battery container according to claim 6.