JP4675707B2 - 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, 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, as 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 nickel plating, and iron is interposed between the steel substrate and 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. A method of reducing the internal resistance of the battery by forming an uneven surface on the inner surface of the battery container and increasing the contact area with the positive electrode mixture or the conductive coating (see, for example, Patent Document 2), nickel layer or iron-nickel By forming a nickel-phosphorus alloy layer on the alloy layer, a method of reducing the internal resistance of the battery by causing fine cracks when forming into the battery container, as in the method of Patent Document 2, (for example, (See Patent Document 3). Furthermore, a method for improving the discharge performance by reducing the contact resistance by coating the inner surface of the battery container with cobalt or a cobalt compound has been proposed (for example, see Patent Document 4).

  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). In addition, with respect to the technologies such as Patent Document 2 and Patent Document 3, a narrow layer is formed by forming a hard layer such as a nickel-tin alloy layer or a nickel-phosphorus alloy layer formed on the steel plate surface used for the battery container inner surface. A feature that excellent battery performance can be obtained by generating microcracks when forming into a container by performing press processing such as processing and squeezing and ironing, and improving adhesion with the positive electrode mixture of alkaline batteries. However, the outermost surface of the nickel-tin alloy layer or the nickel-phosphorus alloy layer 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. Further, in the method of coating a cobalt compound obtained by heat treatment after cobalt plating on a cobalt or nickel layer of Patent Document 4, although there is a certain effect in improving the conductivity of cobalt, after storage of the battery 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 No. 3595347 Japanese Patent Publication No. 07-070320

   In the present invention, a microcrack is generated when the battery container is formed by drawing or ironing, so that sufficient adhesion between the battery container inner surface and the positive electrode mixture can be obtained even after long-term battery storage. An object of the present invention is to provide a plated steel sheet for battery containers, which is obtained and has excellent discharge characteristics by improving conductivity in an alkaline electrolyte.

In order to achieve the object of the present invention, a plated steel sheet for a battery container according to the present invention comprises an iron-nickel alloy layer, an iron-nickel-tin alloy layer, water on the steel sheet on the side that is the inner surface of the battery container. An iron-nickel alloy layer, iron in order from the bottom on a plated steel sheet for a battery container (Claim 1), or a steel sheet on the side of the steel sheet that is the inner surface of the battery container, wherein a cobalt oxide layer is formed A nickel-tin alloy layer, a nickel-tin alloy layer, a hydrated cobalt oxide layer, a plated steel sheet for battery containers (Claim 2), or a side of the steel sheet that is the inner surface of the battery container An iron-nickel alloy layer, a nickel layer, a nickel-tin alloy layer, and a hydrated cobalt oxide layer are formed on a steel plate in order from the bottom. .

Moreover, the battery container of this invention is a battery container (Claim 4) formed by shape | molding the plated steel plate for battery containers in any one of the said (Claims 1-3) in a bottomed cylindrical shape.
The battery of the present invention is a battery (Claim 4) using the battery container of the above (Claim 4).

  The plated steel sheet for battery containers according to the present invention is formed by applying nickel plating to the battery container inner surface side of the steel sheet, then tin plating, then heat treatment, and then forming a hydrated cobalt oxide using an electrolytic method. Can be obtained. When the plated steel sheet for a battery container thus obtained is formed into a battery container, a nickel layer and a tin layer or / and iron, nickel layer and tin layer of the steel base are formed by thermal diffusion on the inner surface of the battery container. Micro cracks are generated in the hard alloy layer, the adhesion with the positive electrode mixture is improved, and excellent discharge characteristics after storage are obtained. Moreover, the hydrated cobalt oxide formed on the outermost layer suppresses the passivation of the alloy layer formed by thermal diffusion of the nickel layer and the tin layer, or / and the iron, nickel layer and tin layer of the steel base, An excellent discharge characteristic can be obtained by forming a layer made of cobalt hydroxide having excellent conductivity in an alkaline electrolyte.

  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, tin plating is subsequently applied to the side of the steel plate on which the nickel plating has been performed that will be the battery container inner surface. Although any known plating bath can be used as the tin plating bath, it is preferable to use a phenolsulfonic acid bath, a halogen bath, or the like that is frequently used as a tin plating bath. The plating adhesion amount of tin 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 depth of microcracks generated during press molding is small, and sufficient adhesion to the positive electrode mixture cannot be obtained, while if it exceeds 5 g / m ² , the thickness of microcracks However, there is a risk that the depth will increase, cracks will reach the steel substrate, and iron will dissolve in the alkaline electrolyte and induce the generation of soot. The tin adhesion amount is less than 1/3 of the nickel adhesion amount by atomic ratio so that the tin layer does not remain alone in the plating layer without being alloyed with the nickel plating layer or the steel substrate after the heat treatment applied after plating. It is necessary to. If tin remains alone without being alloyed, it dissolves in the alkaline electrolyte and degrades battery performance.

After tin plating is performed on the nickel plating layer as described above, heat treatment for alloying the nickel layer and the tin layer or / and the iron, nickel layer and tin layer of the steel base is performed. The heat treatment is performed using a box annealing method or a continuous annealing method in a non-oxidizing protective gas atmosphere. In the case of the box annealing method, it is preferable that the heating temperature is 500 to 650 ° C. and the heating time is 1 to 8 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 treatment under these conditions, nickel and tin are solid-diffused and alloyed. X-ray diffraction confirms that the composition is an intermetallic compound having a composition of Ni ₃ Sn. The temperature below, _Ni 3 Sn ₂ is produced along with _Ni 3 Sn is when heated for example 5 hours at heating temperature of 300 ° C.. The amount of tin dissolved when a LR6 alkaline battery battery container is molded using a plated steel sheet prepared by heat treatment under these heat treatment conditions, and an aqueous potassium hydroxide solution is injected into the battery container, When a plated steel sheet obtained by heating at an appropriate heating temperature, for example, 500 ° C. for 5 hours is formed into a similar battery container and a potassium hydroxide aqueous solution is injected, the amount of dissolution is three times the amount of tin dissolved. Therefore, in order to reduce the amount of tin dissolved in the alkaline electrolyte, it is preferable to use the above-described appropriate heat treatment conditions so that the nickel-tin alloy layer has a composition of Ni ₃ Sn.

  In addition, nickel plating is performed on an unannealed cold-rolled steel sheet that is not annealed after cold rolling, then tin-plating is performed, and then recrystallization annealing of the cold-rolled steel sheet and thermal diffusion of the plating layer are performed simultaneously. It is also possible to do this. Furthermore, when heat treatment is performed after plating, temper rolling is performed at a rolling rate of about 0.8 to 1.5% as necessary, adjustment of mechanical properties (prevention of stretcher strain) and appropriate surface It is also preferable to impart roughness.

After performing nickel plating as described above, and subsequently performing tin plating, heat treatment is performed, and then a cobalt oxide is formed using an electrolytic method. A cobalt oxide can be formed by anodizing using a bath mainly composed of cobalt sulfate and sodium acetate as a treatment bath. The amount of cobalt oxide deposited is preferably in the range of 0.1 to 0.5 g / m ^{2 in} terms of cobalt. If the amount is less than 0.1 g / m ² , the effect of improving the conductivity in a good alkaline electrolyte by cobalt cannot be obtained. On the other hand, if the amount exceeds 0.5 g / m ² , the improvement effect reaches saturation, and processing time is not required. It becomes economy.

  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.

A hot rolled sheet of the above steel grade I or II is subjected to cold rolling and electrolytic cleaning by a conventional method to obtain a cold rolled sheet having a thickness of 0.25 mm, and in the case of steel grade I, box annealing Using this method, heat treatment was performed at a soaking temperature of 640 to 680 ° C. for a soaking time of 8 hours. 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), b) and e). In the case of steel type II, a cold-rolled and electrolytically cleaned plate is used as the plating base plate, and annealing is performed at a heating temperature of 800 ° C. and a heating time of 2 minutes in a continuous annealing furnace in the following steps c), d) and f). It was.
B) Low carbon aluminum killed steel (I) → Cold rolling → Electrolytic cleaning → Annealing (box type annealing furnace) → Temper rolling → Nickel plating (inside and outside) → Tin plating (inside) → Heat treatment (box type) (Annealing method) → Temper rolling → Cobalt oxide coating (inner side)
B) Low carbon aluminum killed steel (I) → cold rolling → electrolytic cleaning → annealing (box annealing furnace) → temper rolling → nickel plating (inside and outside) → tin plating (inside) → heat treatment (box type) Annealing method) → Temper rolling c) Extremely low carbon aluminum killed steel (II) → Cold rolling → Electrolytic cleaning → Nickel plating (inner and outer side) → Tin plating (inner side) → Heat treatment (continuous annealing method) → Tempering Rolling → Cobalt oxide coating treatment (inner surface side)
D) Extremely low carbon aluminum killed steel (II) → Cold rolling → Electrolytic cleaning → Nickel plating (inside and outside side) → Tin plating (inside side) → Heat treatment (continuous annealing method) → Tempered rolling e) Low carbon aluminum killed steel (I) → Cold rolling → Electrolytic cleaning → Annealing (box-type annealing furnace) → Nickel plating (inside and outer side) → Heat treatment (box-type annealing method) → Temperature rolling f) Extremely low carbon aluminum killed steel (II) → Cold rolling → Electrolytic cleaning → Annealing (box annealing furnace) → Nickel plating (inside and outside) → Heat treatment (continuous annealing) → Temper rolling → Cobalt oxide coating (inside)
Each plating treatment in the steps (a) to (f) was performed under the following conditions.

<Nickel plating>
Bath composition Nickel sulfate 300g / L
Nickel chloride 35g / L
Boric acid 40g / L
Bit inhibitor (sodium lauryl sulfate) 0.4mL / L
Anode Nickel Pellets (Titanium basket filled with INP CO. S pellets and equipped with polypropylene anode bag)
Stirring air stirring
pH 4.0-4.6
Bath temperature 55-60 ° C
Current density 10A / dm ²

<Tin plating>
Bath composition Stannous sulfate 30g / L
Phenolsulfonic acid 60g / L
Ethoxylated α-naphthol 5g / L
Anode Tin plate Agitation Plating bath circulation Bath temperature 45-50 ° C
Current density 5A / dm ²

<Cobalt oxide anodizing>
Bath composition Cobalt sulfate 25g / L
Sodium acetate 8g / L
Sodium sulfate 15g / L
Cathode Platinum plating (3μm thickness) titanium plate)
Stirring air stirring
pH 8.5-9.0 (adjusted with aqueous ammonia)
Bath temperature 40-45 ° C
Anode potential 1V

  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 batteries shown in Tables 2 and 3 (sample numbers 1 to 10) 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 4.

  As shown in Table 3, when the battery container is formed and processed using the plated steel sheet for a battery container according to the present invention in which a cobalt oxide is formed on the outermost layer on the inner surface side of the battery container, a cobalt oxide is formed. It is recognized that all of the short-circuit current, heavy load continuous discharge characteristics, and heavy load simple discharge characteristics after storage of the battery are improved as compared with the case of using the plated steel sheet for battery containers.

The plated steel sheet for battery containers according to the present invention, in which nickel plating is applied to the battery container inner surface side of the steel sheet, then tin plating is performed, and then heat treatment is performed, and then hydrated cobalt oxide is formed using an anodic electrolysis method. Micro-cracks are formed on the inner surface of the molded battery case, and excellent discharge characteristics after storage are obtained by improving the adhesion to the positive electrode mixture, and at the same time, hydrated cobalt formed on the outermost layer The oxide forms a layer made of cobalt hydroxide having excellent conductivity in an alkaline electrolyte without passivating the nickel-based alloy layer, so that excellent discharge characteristics after storage of the battery can be obtained.

Claims (5)

An iron-nickel alloy layer, an iron-nickel-tin alloy layer, and a hydrated cobalt oxide layer are formed in order from the bottom on a steel plate on the side that is the inner surface of the battery case. steel sheet. An iron-nickel alloy layer, an iron-nickel-tin alloy layer, a nickel-tin alloy layer, and a hydrated cobalt oxide layer are formed in order from the bottom on the steel plate on the side that is the inner surface of the battery container of the steel plate. A plated steel sheet for battery containers. An iron-nickel alloy layer, a nickel layer, a nickel-tin alloy layer, and a hydrated cobalt oxide layer are formed in order from the bottom on a steel plate on the side that is to be the battery vessel inner surface of the steel plate. Plated steel sheet. The battery container formed by shape | molding the plated steel plate for battery containers of any one of Claims 1-3 in a bottomed cylindrical shape. A battery comprising the battery container according to claim 4.