JP2018160387A - Alkaline battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alkaline battery capable of suppressing degradation in output characteristics of a battery under a high-temperature environment or long-term storage.SOLUTION: The alkaline battery includes: a bottomed battery case serving as a negative terminal of an armored body air-tightly housing a power generation element as well; a sealing plate having an insulation gasket and a safety valve; and a power generation element sealed by the battery case and the sealing plate, and has a plating layer formed on the inner surface side of a base material layer of the battery case. The plating layer contains at least two types selected from a group comprised of nickel, zinc and tin.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an alkaline storage battery, and more particularly to a battery case used for an alkaline storage battery.

  An alkaline storage battery that uses a negative electrode containing a hydrogen storage alloy or cadmium as an electrode active material can be used in a wide current range, and is therefore widely used as a power source for various devices. In particular, in recent years, use has been expanded in applications such as a main power source for electronic devices such as hybrid vehicles and portable devices, and a backup power source such as an uninterruptible power supply. Recently, it is required to be able to charge in a short time or discharge with a large current. Therefore, stable battery characteristics are required in order to obtain high output characteristics even in a wide temperature range and after a long period of time.

  Therefore, Patent Document 1 proposes an alkaline storage battery excellent in high-rate discharge characteristics and cycle life characteristics by paying attention to the adhesion between the inner peripheral wall of the outer can and the electrode group and its space.

JP2013-122862A

  However, in the method of Patent Document 1, the discharge performance deteriorates when discharged with a large current, particularly in a high temperature environment or after long-term storage.

  In view of the above, an object of the present invention is to provide an alkaline storage battery having high output characteristics even in a high temperature environment or after long-term storage.

  As a result of intensive studies to achieve the above object, the present invention provides at least a plating layer formed on the outermost surface of the battery case that also serves as the negative electrode terminal, selected from the group consisting of nickel, zinc, and tin. The present invention relates to an alkaline storage battery using two kinds of metals.

  According to the present invention, it is possible to reduce the deterioration of the output characteristics of the alkaline storage battery even in a high temperature environment or after long-term storage.

It is a longitudinal section showing the composition of the cylindrical alkaline storage battery concerning one embodiment of the present invention.

  Hereinafter, with reference to FIG. 1, the cylindrical alkaline storage battery which concerns on one Embodiment of this invention is demonstrated. However, the following embodiments do not limit the technical scope of the present invention. The alkaline storage battery according to this embodiment of the present invention includes a power generation element and an exterior body that hermetically houses the power generation element. A battery case 4 having a bottomed cylindrical shape that also serves as a negative electrode terminal of an exterior body that hermetically houses a power generation element, an electrode group that is a power generation element housed in the battery case 4, and an alkaline electrolyte (not shown). In the electrode group, the negative electrode 1, the positive electrode 2, and the separator 3 interposed therebetween are spirally wound. A sealing plate 7 including a safety valve 6 is disposed in the opening of the battery case 4 via an insulating gasket 8, and the alkaline storage battery is hermetically sealed by caulking the opening end of the battery case 4 inward. The sealing plate 7 also serves as a positive electrode terminal, and is electrically connected to the positive electrode 2 via the positive electrode current collector plate 9.

  In such an alkaline storage battery, an electrode group is accommodated in a battery case 4, an alkaline electrolyte is injected, a sealing plate 7 is disposed in an opening of the battery case 4 via an insulating gasket 8, and the battery case 4 Can be obtained by caulking and sealing. At this time, the negative electrode 1 of the electrode group is electrically connected by contacting the battery case 4 at the outermost periphery. Further, the positive electrode 2 of the electrode group and the sealing plate 7 are electrically connected via the positive electrode current collector plate 9. Here, at least a plating layer is provided on the inner surface of the battery case 4. The plating layer includes at least two metals selected from the group consisting of nickel, zinc, and tin.

  The plating layer on the inner surface of the battery case 4 includes at least two kinds of metals selected from the group consisting of nickel, zinc, and tin. Even if the alkaline storage battery is stored in a high-temperature environment or for a long period of time, this plating layer suppresses an increase in resistance on the surface of the negative electrode can because the plating layer remains as it is without being corroded.

Usually, a battery case of an outer package that also serves as a negative electrode terminal of an alkaline storage battery uses a steel plate having nickel plating layers on the inner surface and the outer surface. When such a battery case is used, a corrosion product such as nickel acid (HNiO ₂ ⁻ ) is formed in the nickel plating layer on the inner surface in a strong alkali.

  This corrosion product has a lower electronic conductivity than nickel, and the resistance of the surface of the negative electrode can increases. For this reason, the negative electrode has a high contact resistance at the portion in pressure contact with the battery case, and in particular, it has a high output characteristic in which charging and discharging are performed with a large current. Further, when the battery is used for a long period of time or used at a high temperature, the thickness of the corrosion product layer is increased, the resistance is further increased, and the high output characteristics are remarkably deteriorated.

  The plated layer containing at least two kinds of metals selected from the group consisting of nickel, zinc, and tin provided on the inner surface of the battery case 4 of the present invention forms a corrosion product having high resistance even in a charging environment. As a result, resistance is unlikely to increase. Further, since the composition does not change even when discharged, the resistance value of the negative electrode terminal does not increase under charge / discharge, long-term storage or a high temperature environment, and excellent output characteristics can be maintained.

  By using at least two metals selected from the group consisting of nickel, zinc, and tin according to the present invention, an effect that cannot be obtained with zinc or tin alone can be obtained. Although the detailed mechanism is unknown, it is considered that a local battery between metals having different ionization tendency is formed, and the form such as an oxide film on the outermost surface of plating is different from that using a single body.

  This plating layer contains at least two kinds of metals selected from the group consisting of nickel, zinc and tin, but when nickel is essential and contains two kinds of metals, that is, a nickel zinc plating layer or nickel tin plating In the case of forming a layer, the composition of the plating layer is preferably such that the nickel ratio is 30% by mass or less, more preferably 5 to 20% by mass, and 7 to 17% by mass. By setting this ratio, the resistance value of the plating layer is less likely to increase even during long-term storage or in a high temperature environment.

  Moreover, when forming the zinc tin plating layer containing zinc and tin as the two kinds of metals, the composition of the plating layer is preferably such that the ratio of zinc is 35% by mass or less, 1-30% by mass, 5-5% 15 mass% is further more preferable. When the zinc ratio increases, it becomes difficult to form a plating layer. By setting this ratio, the resistance value of the plating layer is less likely to increase even during long-term storage or in a high temperature environment.

  The plating layer may contain three of nickel, zinc, and tin. In that case, it is preferable to adjust the ratio of zinc and tin to the ratio of the zinc-tin plating layer and to adjust the ratio of nickel to 1 to 10% by mass with respect to the entire plating layer.

  The thickness of the plating layer is preferably 0.5 to 10 μm, and more preferably 1 to 3 μm.

  Further, a chromate treatment layer may be provided on the surface of the plating layer.

  Further, a plating layer similar to the inner surface may be formed on the outer surface of the battery case 4. When forming a plating layer on the outer surface, a nickel zinc plating layer is preferable because of its high hardness.

  The base material layer of the battery case 4 is a main material constituting the skeleton of the battery case. It is desirable to include at least one selected from the group consisting of ordinary steel and carbon steel from the viewpoint of obtaining a high strength skeleton and workability.

  Normal steel is steel such as SS material, SM material, and SPCC material specified by JIS. Carbon steel is steel such as S10C, S20C, S30C, S45C, and S55C, and belongs to alloy steel for machine structure. However, when using ordinary steel or carbon steel for the base material layer of the battery, at least the surface selected from the group consisting of the nickel plating layer for rust prevention or the nickel, zinc and tin of the present invention is provided on the outer surface side of the battery case 4. It is desirable to form a plating layer made of two kinds of metals.

  As the base material layer of the battery case 4, stainless steel can also be used. The base material layer may be a laminate of stainless steel and ordinary steel and / or carbon steel. As the stainless steel, 400 series ferritic stainless steel such as SUS430, SUS444 and SUS447, 300 series austenitic stainless steel such as SUS304, SUS305 and SUS316, and duplex stainless steel such as SUS329 can be used.

  Further, a nickel alloy such as NAS 254 and 354 having a composition close to stainless steel can be used as the base material layer of the battery case 4. When stainless steel is used as a base material, a plating layer for preventing rust of ordinary steel and carbon steel is not required.

  The sealing plate 7 has a base material layer and a plating layer on the surface thereof. The base material layer of the sealing plate 7 is not particularly limited as long as it has corrosion resistance and strength, and stainless steel, ordinary steel, carbon steel, and the like can be used. A nickel plating layer for reducing contact resistance or a plating layer made of at least two metals selected from the group consisting of nickel, zinc and tin according to the present invention is formed on the surface of the base material layer of the sealing plate 7. May be.

  Hereinafter, the power generation element will be described. In the positive electrode 2, a conductive base material having a three-dimensional network structure is filled with a positive electrode mixture. The positive electrode mixture includes, for example, a positive electrode active material, a binder, a thickener, and the like.

  Although it does not specifically limit as a positive electrode active material, Nickel hydroxide etc. which surface-coated cobalt hydroxide etc. can be mention | raise | lifted, such as nickel hydroxide which dissolved solid cobalt and zinc.

  The binder may be either a thermoplastic resin or a thermosetting resin. Specific examples of the binder include styrene-butadiene copolymer rubber (SBR), polyethylene, polypropylene, polytetrafluoroethylene, and the like.

  Examples of thickeners that can impart viscosity to the positive electrode paste include carboxymethyl cellulose and its modified products, polyvinyl alcohol, methyl cellulose, polyethylene oxide, and the like.

  After preparing the positive electrode paste, the conductive base material having a three-dimensional network structure is filled and dried, and the thickness is adjusted by passing through a rolling roll having a predetermined pressure and gap. Thereafter, the electrode plate is cut to a predetermined size, and a part of the end surface is removed by ultrasonic peeling or the like, and the positive electrode lead having conductivity is welded.

  In the negative electrode 1, a negative electrode mixture is applied to a punching metal base material in which openings are periodically provided in a conductive steel plate. A negative electrode mixture consists of a negative electrode active material, a electrically conductive agent, a binder, a thickener, etc., for example.

  Examples of the negative electrode active material include hydrogen storage alloys capable of occluding and releasing hydrogen and cadmium metals.

  The conductive agent is not particularly limited except that it is a material having electron conductivity, and various electron conductive materials can be used. Specifically, for example, graphite such as natural graphite (such as flake graphite), artificial graphite, and expanded graphite, for example, carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black Can be used.

  The binder serves to bind the hydrogen storage alloy powder or the conductive agent to the current collector. The binder may be either a thermoplastic resin or a thermosetting resin. Specific examples of the binder include styrene-butadiene copolymer rubber (SBR), polyethylene, polypropylene, polytetrafluoroethylene, and the like.

  As the thickener, those capable of imparting viscosity to the negative electrode paste, for example, carboxymethylcellulose and modified products thereof, polyvinyl alcohol, methylcellulose, polyethylene oxide and the like can be used.

  After preparing the negative electrode paste, it is applied to a punching metal, dried, and passed through a rolling roll having a predetermined pressure and gap to adjust the thickness. Thereafter, it is cut into a predetermined dimension.

The separator 3 is made of a nonwoven fabric or a sheet-like film in which fibers made from polypropylene and polyethylene are entangled. As these separators, those whose basis weight (weight per unit area) is adjusted from 20 g / m ² to 100 g / m ² are more preferable. Further, it is more preferable that the thickness is adjusted from 50 μm to 200 μm. These separators are subjected to a hydrophilic treatment in order to impart hydrophilicity. Examples of the hydrophilic treatment for the separator include sulfonation treatment, fluorine treatment, and plasma treatment.

  EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples below, but the present invention is not limited to these examples.

Example 1
A cylindrical alkaline storage battery shown in FIG. 1 was produced. First, water is added to and kneaded with nickel hydroxide (positive electrode active material), zinc oxide (additive), polytetrafluoroethylene (binder), and carboxymethylcellulose (thickener) coated with a cobalt compound. A positive electrode paste was prepared. This paste was filled in a foamed nickel porous body (conductive substrate) having a three-dimensional network structure, dried and rolled. After rolling, the substrate was cut and a nickel plate serving as a positive electrode lead was welded, and both front and back surfaces of the welded portion were covered with polypropylene insulating tape. The positive electrode (positive electrode plate) 2 was obtained by the above configuration.

On the other hand, hydrogen storage alloy Mm (Misch metal) Ni _3.6 Co _0.7 Mn _0.4 Al _0.3 (negative electrode active material), carbon black (conductive agent), styrene-butadiene rubber copolymer fine particles (binding) Agent) and carboxymethylcellulose (thickening agent) were added with water and kneaded to prepare a negative electrode paste. This paste was applied to punching metal and rolled. After rolling, it was cut into an electrode plate to produce a negative electrode (negative electrode plate) 1. An exposed portion of the core material was provided at one end portion along the longitudinal direction of the negative electrode 1.

  The electrode plate size was adjusted so that the capacitance ratio of the negative electrode 1 and the positive electrode 2 was 1.5 times the negative electrode capacity.

  Using the positive electrode 2 and the negative electrode 1 obtained above, a cylindrical alkaline storage battery (nickel metal hydride storage battery) having the structure shown in FIG. 1 was produced. More specifically, first, an electrode group was formed by winding these layers in a spiral shape with the separator 3 interposed between the positive electrode 2 and the negative electrode 1. As the separator 3, a sulfonated polypropylene separator was used.

  The other end of the positive electrode lead welded to the positive electrode 2 was welded to a positive electrode current collector plate 9 electrically connected to the sealing plate 7. The electrode group also serves as a bottomed cylindrical negative electrode terminal, and a zinc-tin plating layer consisting of 12% by mass of zinc and 88% by mass of tin is provided at 2 μm on the inner surface side of the base steel plate and 3 μm on the outer surface side The battery case 4 was housed, and the outermost periphery of the negative electrode 1 and the inner wall of the battery case 4 were brought into contact with each other to electrically connect them.

The outer periphery in the vicinity of the opening of the battery case 4 was recessed to provide a groove, and an alkaline electrolyte was injected into the battery case 4. As the alkaline electrolyte, lithium hydroxide dissolved in an aqueous solution containing sodium hydroxide at a concentration of 7.5 mol / dm ³ (specific gravity: 1.3) so as to have a concentration of 20 g / dm ³ is used. It was.

Next, a sealing plate 7 provided with a positive electrode terminal 5 and a safety valve 6 was attached to the opening of the battery case 4 via an insulating gasket 8. A cylindrical alkaline storage battery A1 was produced by caulking the open end of the battery case 4 toward the insulating gasket 8 and sealing the battery case 4.
A battery A2 was produced in the same manner as the battery A1, except that a nickel tin plating layer containing 12% by mass of nickel and 88% by mass of tin was formed instead of the battery case provided with the zinc tin plating layer.

A battery A3 was produced in the same manner as the battery A1, except that instead of the battery case provided with the zinc-tin plating layer, a zinc-nickel plating layer containing 88% by mass of zinc and 12% by mass of nickel was formed.
A battery B1 of a comparative example was produced in the same manner as the battery A1, except that a battery case provided with a nickel plating layer was used instead of the battery case provided with a zinc-tin plating layer.

  The alkaline storage batteries A1 to A3 and B1 were charged at an environmental temperature of 20 ° C. at a charging rate of 0.1 It for 16 hours after being activated, and then left at an environmental temperature of 25 ° C. for 3 hours. The battery was discharged to 1.0 V at a discharge rate of 0.2 It at an environmental temperature of ° C. Such charge and discharge was repeated for 2 cycles, and the discharge capacity at the second cycle was determined. These results are shown in each table, normalized with the result of B1 being 100.

  Further, this battery was further charged for 16 hours at a charging rate of 0.1 It, and then stored at 20 ° C. and 45 ° C. for 3 months. The battery after storage was discharged to 1.0 V at a discharge rate of 0.2 It at an ambient temperature of 20 ° C. After charging for 16 hours at a charging rate of 0.1 It, it was left for 3 hours at an environmental temperature of 25 ° C., and then discharged to 1.0 V at an environmental temperature of 20 ° C. and a discharging rate of 0.2 It. Such charge and discharge was repeated for 2 cycles, and the discharge capacity at the second cycle was determined. Subsequently, after charging for 16 hours at a charging rate of 0.1 It, left for 3 hours at an environmental temperature of 25 ° C., and then discharged to 1.0 V at an environmental temperature of 20 ° C. at a discharging rate of 3 It. Asked. The results are shown in Table 1.

  A1 to A3 of alkaline storage batteries using a battery case provided with a plating layer containing at least two kinds of metals selected from the group consisting of nickel, zinc, and tin showed high discharge capacities at all temperatures.

(Example 2)
Cylindrical alkaline storage batteries A4 to A9 were produced in the same manner as the battery A1 except that the composition of the zinc-tin plating layer was changed, and the same evaluation as in Example 1 was performed. The results are shown in Table 2.

  All batteries A4 to A9 showed high discharge capacity. The higher the zinc ratio in the plating layer, the higher the discharge capacity, and the highest discharge capacity was obtained especially when the zinc ratio was around 20% by mass.

  In the present invention, the cylindrical battery has been described, but the same good effect can be obtained even with a square or button battery. Moreover, the same good effect is acquired also when the active material of a negative electrode is changed.

  The alkaline storage battery using the battery case provided with the plating layer of the present invention can obtain excellent high output characteristics even when used in a wide temperature range including high temperature. Therefore, for example, it is useful as an alkaline storage battery used as a power source for various electronic devices, transportation devices, power storage devices, and the like, and is particularly suitable for use as an in-vehicle power source and power storage devices such as an electric vehicle and a hybrid vehicle.

DESCRIPTION OF SYMBOLS 1 Negative electrode 2 Positive electrode 3 Separator 4 Battery case 5 Positive electrode terminal 6 Safety valve 7 Sealing plate 8 Insulating gasket 9 Positive electrode current collecting plate

Claims (7)

A battery case having a bottom that also serves as a negative electrode terminal of an exterior body that hermetically houses the power generation element, an insulating gasket, a sealing plate including a safety valve, and a power generation element sealed by the battery case and the sealing plate,
It has a plating layer provided on the inner surface side of the base material layer of the battery case,
The said plating layer is an alkaline storage battery containing the at least 2 sort (s) of metal selected from the group which consists of nickel, zinc, and tin.   The alkaline storage battery according to claim 1, wherein the plating layer includes nickel and at least one metal selected from the group consisting of zinc and tin.   The alkaline storage battery according to claim 2, wherein the plating layer contains 30 mass% or less of nickel.   The alkaline storage battery according to claim 2, wherein the plating layer contains 5 to 20 mass% of nickel.   The alkaline storage battery according to claim 1, wherein the plating layer includes at least tin and zinc.   The alkaline storage battery according to claim 5, wherein the plating layer contains 35 mass% or less of zinc.   The thickness of the said plating layer is an alkaline storage battery of any one of Claims 1-6 which is 0.5-10 micrometers.

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