JP2003017078A - Zinc alkaline battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zinc alkaline battery with excellent high-rate discharging characteristics and suitable for heavy load discharging and medium load discharging. SOLUTION: This zinc alkaline battery has an outer can 1 also acting as a positive terminal; a hollow cylindrical positive electrode 2 housed in the outer can 1 and comprising a positive mix containing nickel hydroxide base particles and conductive material particles; a gelled negative electrode 4 housed in the hollow cylinder of the positive electrode 2 through a separator 3 and containing alloy particles mainly comprising zinc; and an insulating gasket 6 electrically insulating a terminal 10 of the negative electrode from the outer can 1 and liquid-tightly sealing an opening end of the outer can 1, and an expansion suppressing member 9 of the positive electrode 2 is fit and arranged between the end surface of the hollow cylindrical positive electrode 2 and the insulating gasket 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zinc alkaline battery, and more particularly to a zinc alkaline battery having an improved medium load discharge characteristic without impairing the original high load discharge characteristic.

[0002]

2. Description of the Related Art For example, zinc alkaline batteries are used as a power source for portable electronic devices such as portable radios and cassette recorders. It is also known that in the structure of this type of zinc-alkaline battery, the cost can be reduced by making the battery element (electromotive portion) have an inside-out structure.

That is, a hollow cylindrical body made of a positive electrode mixture containing nickel hydroxide particles as a positive electrode active material and a conductive agent is used as a positive electrode, and a cylindrical separator having a bottom is inserted and arranged in the hollow of the positive electrode. The bottom-out tubular separator has an inside-out type structure in which a gelled negative electrode material containing zinc as a main component is filled. Further, by adopting the inside-out type structure, productivity is improved, etc. as compared with the case of adopting the spiral type structure in which a laminate of a sheet-shaped positive electrode, a separator and a negative electrode is wound, and as a result, low It is possible to provide a high-capacity zinc alkaline battery at low cost.

[0004]

As described above, the zinc-alkaline battery having the inside-out type battery element is advantageous in terms of productivity and cost reduction, but it is more advantageous than the spiral-type structure. Since the facing area between the positive electrode and the negative electrode is small and the internal volume of the battery is fixed, there is a problem that it is difficult to significantly increase the battery capacity. That is, since the high rate discharge characteristics or the heavy load discharge characteristics are inferior, improvements and studies are being made with a focus on improving these characteristics.

As a means for increasing the capacity of the zinc-alkaline battery, if the molding density of the positive electrode mixture is extremely increased, the friction problem of the molding die of the positive electrode mixture molding machine, the problem of the storage after mounting and sealing in the battery outer can, Mass expansion and battery reliability may be impaired, such as poor sealing of the battery outer can top due to expansion. In addition, the increase in the molding density of the positive electrode mixture is
The reduction in the amount of the electrolytic solution held causes the deterioration of the heavy load discharge characteristics as the utilization rate of the positive electrode active material decreases.

By the way, when a zinc alkaline battery is used, a heavy load discharge mode is usually adopted, but a medium load discharge mode is often adopted. That is, in an electronic device using a zinc alkaline battery as a power source, a driving load may be reduced and a medium-load discharging usage mode may be adopted depending on the selection of the usage mode. It can be said that it is advantageous in terms of energy saving and resource saving if the medium load discharge can be performed without any problem when the driving load is reduced. In other words, if a zinc alkaline battery with an excellent medium load characteristic appears without impairing the heavy load characteristic and without increasing the active material, a highly versatile portable power source can be provided.

However, in the case of the above-mentioned zinc alkaline battery using nickel hydroxide as a positive electrode active material, when the medium load discharge is performed, the duration at the end of the discharge is reduced, and thus it is not suitable for the medium load discharge in practice. There is. With respect to this point, the present inventor has paid attention to the expansion phenomenon of the positive electrode (positive electrode mixture) after medium-load discharge, and made intensive studies. As a result, the expansion of the positive electrode mixture is caused by the change in the crystal structure of nickel hydroxide, and the contact between the active material and the conductive agent in the positive electrode mixture is deteriorated due to this expansion phenomenon, and it is difficult to discharge the medium load under a medium load. It was confirmed that the duration time of the end of discharge decreased.

The problem of the above-mentioned medium load discharge characteristics is that the surface of nickel hydroxide particles is a cobalt compound as a positive electrode active material.
For example, when a higher order cobalt oxide having a valence of more than 2 is used to improve the conductivity between the nickel hydroxide particles, the same phenomenon occurs. In other words, a zinc-alkaline battery that is compatible with the recent increase in capacity and functionality of portable electronic devices and that has excellent high-rate discharge characteristics as well as heavy-load discharge characteristics and medium-load discharge characteristics in power supply batteries has been developed. Although required, at present,
It is expected that zinc-alkaline batteries that do not exhibit sufficient characteristics and that exhibit high-rate discharge characteristics capable of medium-load discharge will be developed.

The present invention has been made in consideration of the above circumstances, and an object thereof is to provide a zinc alkaline battery suitable for heavy load discharge and medium load discharge while adopting an inside-out type structure excellent in productivity. .

[0010]

According to the invention of claim 1, a battery outer can also serving as a positive electrode terminal, and a positive electrode mixture containing nickel hydroxide particles and conductive agent particles housed and mounted in the battery outer can. A hollow cylindrical positive electrode composed of, a gel-like negative electrode containing alloy particles containing zinc as a main component and housed in the hollow cylinder of the positive electrode via a separator; A zinc-alkaline battery having an insulating gasket that electrically insulates against a can and that liquid-tightly seals an open end of the battery outer can, between the hollow cylindrical positive electrode end face and the insulating gasket, The zinc alkaline battery is characterized in that a positive electrode expansion suppressing member is fitted and arranged.

According to a second aspect of the present invention, in the zinc alkaline battery according to the first aspect, the expansion suppressing member of the positive electrode has a ring shape.

The invention according to claim 3 is the zinc alkaline battery 2 according to claim 1 or 2, wherein the expansion suppressing member of the positive electrode is made of a nickel-plated steel plate.

In the inventions of claims 1 to 3, the nickel hydroxide type which mainly constitutes the positive electrode mixture is, for example, nickel hydroxide, nickel oxyhydroxide, a mixed nickel hydroxide-nickel oxyhydroxide system (mixed system), Alternatively, they are a eutectic of zinc and cobalt. And as these nickel hydroxide type | system | group particles, generally, an average particle diameter is 5 to 1
The one having a thickness of about 5 μm is used.

In the first to third inventions, the conductive agent is particles of graphite, carbon black such as Ketjen black or acetylene black. The amount of the conductive agent in the positive electrode mixture is about 3 to 15% by mass, preferably 5 to 12% by mass, and more preferably 7-1.
It is selected within the range of 0% by mass. Here, if the amount of the conductive agent in the positive electrode mixture is less than 3% by mass, it is difficult to obtain sufficient current collecting efficiency, and the high rate discharge characteristics tend to deteriorate. On the other hand, if it exceeds 15% by mass, the amount of the positive electrode active material is reduced, resulting in a decrease in battery capacity.

In the invention of claims 1 to 3, the gelled negative electrode contains a zinc alloy, which is a negative electrode active material, as a main component, and the zinc alloy has a large surface area and is capable of discharging a large current. In order to be able to deal with, for example, an average particle size of 10
A powder (particles) of about 0 to 350 μm is preferable. That is, when the average particle diameter is about 100 μm or less, not only is it difficult to uniformly mix the electrolytic solution and the gelling agent, but also destabilization such as easy oxidation due to the active surface. Tend to do. On the other hand, if the average particle size exceeds about 350 μm, it may be difficult to cope with a large current discharge due to the reduction of the surface area.

The gelled negative electrode is prepared by adding an electrolytic solution and a thickener to the zinc alloy powder. Incidentally, as the zinc alloy, a zinc alloy containing no mercury and lead, which is known as a smoothed zinc alloy, is preferable,
Specifically, indium 0.06 mass% and bismuth 0.
A zinc alloy containing 014% by mass and 0.0035% by mass of aluminum is preferable because it has an effect of suppressing hydrogen gas generation. Particularly, indium and bismuth are preferable in order to improve the discharge performance.

Further, examples of the thickener used for preparing the gelled negative electrode material include polyvinyl alcohol, polyacrylic acid salt, CMC, methyl cellulose, alginic acid and the like. In particular, polyacrylic acid salt is resistant to alkali. It is preferable because it has excellent chemical properties. The electrolytic solution used for gelation is also an aqueous solution containing an alkaline substance such as potassium hydroxide or sodium hydroxide as an electrolyte.

In the first to third aspects of the invention, the separator for separating the tubular positive electrode and the gelled negative electrode filled in the central space of the tubular positive electrode is made of, for example, acetalized polyvinyl alcohol fiber, polyvinyl alcohol fiber, or other non-woven fabric. It is a cylindrical body with a bottom made of. The insulating gasket that electrically insulates the current collector of the negative electrode from the battery outer can and liquid-tightly seals the open end of the battery outer can is, for example, rubber having chemical resistance and electrical insulation. And is attached to the reduced diameter portion on the open end side of the battery outer can.
Then, the metal sealing plate (metal bottle) also serving as the negative electrode terminal, which is mounted on the negative electrode current collector with its edge portion facing the insulating gasket, and the open end of the battery outer can are squeezed through the insulating gasket. Create a liquid-tight sealing structure.

According to the first to third aspects of the invention, in forming the liquid-tight sealing structure of the zinc alkaline battery, the positive electrode expansion suppressing member fitted and arranged between the positive electrode end face and the insulating gasket is: Generally, it is a ring-shaped or ring-shaped divided piece that is superposed on the end surface of the cylindrical positive electrode. The expansion suppressing member is made of, for example, steel, nickel-plated steel, chemical resistant plastics (for example, fluororesin), glass, ceramics, or the like having alkali resistance, workability, and heat resistance. It is a thing.

In a zinc-alkaline battery, the upper end surface of the cylindrical positive electrode is usually separated from the insulating gasket. Therefore, the expansion suppressing member is fitted and arranged as a member in this isolation region, but the insulating gasket surface facing the cylindrical positive electrode end surface is projected (may be divided) to suppress the expansion. You may make it serve also as a member for use. Further, the expansion suppressing member may be fitted and arranged so as to fill a part or the whole of the isolation region so as to obtain an expansion suppressing action. Further, when the expansion suppressing member has a ring shape, the expansion suppressing effect is promoted by forming the surface of the outer can to be in contact with the inner wall surface into a relatively large plate shape.

According to the first to third aspects of the invention, the cylindrical positive electrode enclosed and mounted in the battery outer can is prevented from being expanded in the axial direction. That is, due to the fitting / arrangement of the expansion suppressing member, the expansion due to the change in the crystal structure of nickel hydroxide in the positive electrode after the medium load discharge is mechanically,
And it is easily suppressed and prevented. Therefore, good contact between the active material particles in the positive electrode mixture and the conductive agent is maintained even after medium-load discharge. Further, to mention, the function as a general-purpose zinc-alkaline battery having an improved heavy load discharge characteristic and an improved medium load discharge characteristic can be obtained.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments will be described below with reference to FIG.

(Preparation of Positive Electrode Active Material)

For example, cobalt hydroxide powder is added to nickel hydroxide particles doped with zinc and cobalt, and an aqueous sodium hydroxide solution is sprayed while stirring in an air atmosphere. Subsequently, microwave heating is performed to form a cobalt high-order oxide layer on the surface of the nickel hydroxide particles to obtain composite nickel hydroxide particles having excellent conductivity. Incidentally, an oxidizing agent such as sodium hypochlorite may be added to the above reaction system to proceed with oxidation to obtain composite nickel oxyhydroxide particles having the cobalt higher oxide layer formed thereon.

The positive electrode active material can be manufactured by the following means. That is, cobalt particles or cobalt compound particles, a binder such as CMC (carboxymethyl cellulose), and water are added to and mixed with particles containing nickel hydroxide as a main component, and particles on the surface containing nickel hydroxide as a main component are added, Composite nickel hydroxide particles can also be obtained by coating cobalt particles or cobalt compound particles.

Further, the positive electrode active material can be manufactured by the following method. That is, particles having nickel hydroxide as a main component are dispersed in an aqueous medium, and yttrium, erbium, ytterbium, calcium oxide or fluoride particles are added to this dispersion system to obtain a capacity retention rate during storage. An improved positive electrode active material can be manufactured. Here, the oxide such as yttrium is, for example, Y
₂ O ₃ , Er ₂ O ₃ , Yb ₂ O ₃ , and fluoride are
For example, CaF ₂ or the like. If the addition amount of these is less than 0.1% by mass with respect to nickel hydroxide, the effect of the addition is insufficient, and if it exceeds 10% by mass, the problem of capacity decrease occurs. Chosen within.

(Negative electrode material)

The negative electrode active material contains a zinc alloy as a main component, and the zinc alloy has a morphology of, for example, an average particle size of 1 so that the surface area can be increased to cope with large current discharge.
A powder (particles) having a size of about 00 to 350 μm is preferable. That is, when the average particle size is about 100 μm or less, not only it becomes difficult to uniformly mix the electrolytic solution and the gelling agent, but also destabilization such as easy oxidation due to the active surface is caused. Tend. On the other hand, if the average particle size exceeds about 350 μm, it may be difficult to cope with a large current discharge due to the reduction of the surface area.

The electrolytic solution is prepared by dissolving an alkaline substance such as potassium hydroxide or sodium hydroxide in water to a concentration of about 7 to 11 mol / l. The prepared electrolytic solution contains, for example, zinc oxide or hydroxide. It is desirable to add zinc compounds such as zinc, especially zinc oxide. By thus adding the zinc compound to the alkaline electrolyte and allowing the zinc ions to be present in advance, self-dissolution of the zinc alloy (negative electrode active material) in the alkaline aqueous solution is suppressed or reduced. As the separator, a bottomed cylindrical body made of, for example, a non-woven fabric of acetalized polyvinyl alcohol fiber is prepared.

[Example]

(Production of positive electrode)

Composite nickel hydroxide particles 90 on the surface of which a higher cobalt layer obtained by the means for producing the positive electrode active material is formed.
5.4 parts by weight of graphite powder and 0.1 parts by weight of binder.
Add parts by mass and stir mix for 10 minutes. Then, 4.5 mass parts of 40 mass% potassium hydroxide aqueous solution is added, and it mixes for 30 minutes in a general purpose mixing container, and a mixture is obtained. Next, this mixture is compressed by a roller compactor, crushed by a crusher, and classified to prepare a granular positive electrode mixture, and this granular positive electrode mixture is used as a raw material and has an outer diameter of 13.3 m.
m, an inner diameter of 9.0 mm, and a height (length) of 13.7 mm are pressure-molded into a hollow cylindrical shape to prepare a positive electrode material mixture pellet.

(Preparation of negative electrode)

0.01 parts by weight of indium and 0.
Zinc alloy powder 64.58 having an average particle size of 100 to 300 μm and containing 01 parts by mass and 0.003 parts by mass of aluminum
0.381 parts by mass of polyacrylic acid (gelling agent) is added to parts by mass, and the mixture is stirred and mixed for 5 minutes in a general-purpose mixing container to obtain a uniform mixed system. On the other hand, 0.0006 parts by mass of tetrabutylammonium hydroxide is added to 35 parts by mass of a 35% by mass potassium hydroxide aqueous solution in which 3.5% by mass of zinc oxide is dissolved, and stirred and mixed for 10 minutes to sufficiently disperse. Then, to this dispersion, the zinc alloy powder-based mixture was gradually added over 4 minutes, and at the same time, 200 × 10 ⁵ Pa was added.
The mixture is stirred and mixed under a reduced pressure of (150 mmHg) or less, and further stirred and mixed for 5 minutes under a reduced pressure of 13.3 × 10 ⁵ Pa (10 mmHg) or less to prepare a gelled negative electrode having a substantially uniform composition system. .

(Battery assembly)

Next, using the prepared positive electrode material mixture pellets and gelled negative electrode, a single 3 type zinc alkaline battery whose schematic structure is shown in cross section in FIG. 1 is assembled by a conventional method. In FIG. 1, reference numeral 1 denotes a bottomed cylindrical metal can (exterior can) that also serves as a positive electrode terminal. In the hollow of the metal can 1, three positive electrode material mixture pellets are stacked and again pressure-molded. The prepared positive electrode mixture 2 is filled and mounted. Further, a bottomed cylindrical separator 3 is mounted in the hollow portion of the positive electrode mixture 2, and a gelled negative electrode 4 is filled inside the separator 3.

One end side of a brass negative electrode current collector rod 5 is inserted and arranged in the gelled negative electrode 4, and the outer peripheral surface of the negative electrode current collector rod 5 on the other end side protruding from the gelled negative electrode 4 is inserted. , And a double annular insulating gasket 6 made of polyamide resin is arranged between the inner peripheral surface of the opening of the metal can 1. The insulating gasket 6 is locked by the reduced diameter portion 7 of the metal can 1, and a ring-shaped metal plate 8 is fitted and arranged between the double rings of the insulating gasket 6. .

Further, between the upper end surface of the positive electrode mixture 2 and the lower surface of the insulating gasket 6, a ring-shaped expansion suppressing member made of a nickel-plated steel plate having an outer peripheral edge portion having an inverted L-shaped cross-section is formed. The member 9 is fitted and arranged. Further, the cap-shaped metal sealing plate 10 also serving as the negative electrode terminal is arranged to abut the tip of the negative electrode current collector rod 5. Where the metal can 1
The opening edge of the metal can 1 is bent inward, and the opening edge of the metal can 1 is sealed by the metal sealing plate 10 via the insulating gasket 6. The ring-shaped expansion suppressing member 9 may have an L-shaped cross section at the outer peripheral edge portion or may have a flat plate shape.

[Comparative Example]

In the case of the embodiment, except that the ring-shaped expansion suppressing member 9 fitted and arranged between the upper surface of the positive electrode mixture 2 and the lower surface of the insulating gasket 6 is omitted in the structure of the zinc alkaline battery of the embodiment. Under the same conditions as above, an AA zinc alkaline battery was produced.

After aging for about 48 hours, the above-assembled both zinc alkaline batteries were subjected to a constant current continuous discharge time (heavy load discharge characteristic) of 1500 mA up to 0.9 V and a constant resistance continuous discharge of up to 0.9 V in a temperature atmosphere of 20 ° C. Table 1 shows the results of examining time (medium load discharge characteristics). Table 2 shows the results of examining the amount of gas generated after storage at 60 ° C. for 40 days in an undischarged state. The continuous discharge duration is based on the numerical value of the comparative example,
The numerical value is an average value of 20 zinc-alkaline batteries. Further, the amount of gas generated during storage was measured by decomposing the negative electrode terminal side of the battery in water and collecting it with a graduated cylinder or a buret filled with water.

[0042]

[Table 1]

[0043]

[Table 2]

As can be seen from Table 1, in the case of the structure in which the expansion suppressing member 9 is loaded between the upper end surface of the positive electrode mixture 2 and the lower surface of the insulating gasket 6, the constant current continuous discharge time of 1500 mA (heavy load discharge characteristic) is obtained. The 10 Ω constant resistance continuous discharge time (medium load discharge characteristic) is improved without lowering. After the continuous discharge of 10Ω constant resistance, the zinc alkaline batteries were disassembled and the state of the positive electrode mixture 2 was observed. In the case of the example, expansion of the positive electrode mixture 2 in the axial direction was suppressed / avoided. On the other hand, it was confirmed that the radial expansion of the positive electrode mixture 2 was similar to that in the comparative example.

As can be seen from Table 2, the amount of gas generated was the same in both the examples and the comparative examples after storage at 60 ° C. for 40 days in the undischarged state, and the upper surface of the positive electrode mixture 2 and the insulating gasket 6 were the same. The adverse effect of loading the expansion suppressing member 9 between the lower surface and the lower surface is not recognized.

The present invention is not limited to the above embodiments, but various modifications can be made without departing from the spirit of the invention. For example, in the above, the configuration of the cylindrical AA zinc alkaline battery has been illustrated, but the cylindrical AA type,
It may be a single 2 type, a single 4 type or the like. Of course, the composition of the nickel hydroxide-based positive electrode mixture, the composition of the gelled zinc negative electrode, etc.
It is also possible to adopt the configuration mode of this type of zinc alkaline battery.

[0047]

According to the first to third aspects of the present invention, the expansion and the mechanical arrangement of the expansion suppressing member due to the change in the crystal structure of nickel hydroxide in the positive electrode after the medium load discharge can be prevented by interposing and arranging the expansion suppressing member. In addition, it is easily suppressed and prevented. Therefore, good contact between the active material particles in the positive electrode mixture and the conductive agent is maintained even after medium-load discharge. further,
That is, it is possible to provide a general-purpose zinc alkaline battery having an improved medium load discharge characteristic without any damage to the heavy load discharge characteristic.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main configuration of a zinc alkaline battery according to an embodiment.

[Explanation of symbols]

1 ... Metal can (exterior can) 2 ... Positive electrode mixture 3 ... Separator 4 ... Gel negative electrode 5 ... Negative electrode current collector 6 ... Insulating gasket 7 ... Metal can (exterior can) Reduced diameter portion 8 ... Ring-shaped metal plate 9 ... Expansion suppression member 10 ... Metal sealing plate

Claims (3)

[Claims] 1. A hollow cylindrical positive electrode composed of a battery outer can that also serves as a positive electrode terminal, and a positive electrode mixture containing nickel hydroxide particles and conductive agent particles housed and mounted in the battery outer can. A gelled negative electrode containing alloy particles containing zinc as a main component housed and mounted in the hollow cylinder of the positive electrode via a separator, and a terminal of the negative electrode are electrically insulated from a battery outer can, and A zinc-alkaline battery having an insulating gasket that liquid-tightly seals the open end of the battery outer can, wherein a positive electrode expansion suppressing member is fitted and arranged between the hollow cylindrical positive electrode end surface and the insulating gasket. Zinc alkaline battery characterized by having done. 2. The zinc alkaline battery according to claim 1, wherein the expansion suppressing member of the positive electrode has a ring shape. 3. The zinc alkaline battery according to claim 1 or 2, wherein the expansion suppressing member of the positive electrode is made of a steel plate plated with nickel.