JPH09289021A - Paste type electrode, alkaline secondary battery, and manufacture of alkaline secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly disperse fluororesin in paste, and enhance the adhesion of an active material with a current collector by containing particles mainly comprising fluororesin having an average particle size of 0.2μm or less in a binder. SOLUTION: An electrode group prepared by spirally winding a stack of a positive electrode 2, a separator 3, and a negative electrode 4 is housed in a cylindrical container with bottom 1. The negative electrode 4 is constituted by holding paste containing an active material and a binder in a current collector, and particles mainly comprising fluororesin having an average particle size of 0.2μm or less are contained in binder. The current collector of the positive electrode 2 is made of punched metal having a Vickers hardness of 40-100Hv, and in which the no-hole region is formed at least the edge part, faced to the negative electrode 4, of the winding starting edge part and the winding finishing edge part. The adhesion of the active material with the current collector is enhanced, the capacity is increased, and the life is lengthened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paste type electrode having an improved binder, an alkaline secondary battery, and a method for manufacturing an alkaline secondary battery.

[0002]

2. Description of the Related Art A nickel-hydrogen secondary battery, which is an example of an alkaline secondary battery, includes an electrode group made by placing a separator between a paste-type positive electrode and a paste-type negative electrode in a container together with an alkaline electrolyte. It has a stored structure. The secondary battery is voltage-compatible with a nickel-cadmium secondary battery having a negative electrode containing a cadmium compound instead of the hydrogen storage alloy, and has a higher capacity than the nickel-cadmium secondary battery. Have characteristics.

The paste-type positive electrode is prepared by preparing a paste containing nickel hydroxide particles, a binder and water, and filling or coating the paste on a nickel-plated metal porous body which is a current collector. . On the other hand, the paste-type negative electrode is prepared by preparing a paste containing hydrogen-absorbing alloy powder, a binder, and water, and filling or applying the paste to a punched metal serving as a current collector.

By the way, as the binder for the positive electrode and the negative electrode, those containing polytetrafluoroethylene particles have been widely used.

However, since the paste is water-based, there is a problem that water-repellent polytetrafluoroethylene particles are difficult to disperse in the paste.

In the paste type positive electrode, if the dispersibility of the binder containing the polytetrafluoroethylene particles in the paste is poor, the force of the binder to hold the nickel hydroxide particles in the current collector. And the nickel hydroxide particles fall off from the positive electrode with the progress of the electrode group manufacturing process and charge / discharge cycle. Further, the nickel hydroxide particles that have fallen off come into contact with the negative electrode to cause an internal short circuit.

On the other hand, in the paste type negative electrode, when the dispersibility of the binder containing the polytetrafluoroethylene particles in the paste is poor, the adhesion between the current collector and the hydrogen storage alloy powder is reduced. In addition, there is a problem that the gas absorption performance at the time of overcharge is lowered and the battery internal pressure is increased.

That is, since the nickel-hydrogen secondary battery is an alkaline secondary battery like the nickel-cadmium secondary battery, oxygen gas is generated from the positive electrode by the reaction represented by the following formula (1) during overcharge.

4OH ⁻ → O ₂ + 2H ₂ O + 4e ⁻ (1) The oxygen gas thus generated permeates the separator and is consumed by the reactions shown in the following formulas (2) and (3) on the surface of the hydrogen storage alloy of the negative electrode. As a result, the internal pressure of the battery is suppressed from increasing and sealing is possible.

2MH + 1 / 2O ₂ → 2M + H ₂ O (2) 2M + 2H ₂ O + 2e ⁻ → 2MH + 2OH ⁻ (3) Oxygen gas absorption reaction (2), (3) on the hydrogen storage alloy surface and the alloy surface Occurs at the three-phase interface formed by the electrolytic solution and the oxygen gas. However, if the distribution of the polytetrafluoroethylene particles in the negative electrode is non-uniform, the water repellency cannot be imparted to the negative electrode uniformly, and the distribution of the three-phase interface becomes non-uniform.
Since such a negative electrode has a low oxygen gas absorption performance, the internal pressure of the secondary battery including the negative electrode increases during overcharge.

By the way, Japanese Patent Laid-Open No. 7-73874 discloses an electrode group in which a negative electrode composed of a hydrogen storage alloy electrode, a nickel positive electrode, and a separator for separating the two electrodes are wound on a cylindrical roll having a spiral cross section, alkaline electrolysis. Liquid and a sealed battery case containing a safety valve and containing the electrode group and an electrolytic solution, wherein the hydrogen storage alloy electrode is a mixture of mainly hydrogen storage alloy powder and a punching metal of a conductive support that supports the mixture. The punching metal has a hole diameter of 1.0 mm or more and 2.5 mm or less, and a vertical angle of a triangle formed by connecting the centers of three adjacent holes is 46 mm.
To 58 ° and a base angle of 67 to 61 ° are punched in a punching pattern forming an isosceles triangle, and a solid portion is formed at a portion corresponding to an axial end portion of the cylindrical roll at an end portion of the punched portion. And a sealed nickel-hydrogen storage battery having a base of the triangle in a plane perpendicular to the axis of the cylindrical roll. Further, in the examples of the publication, the polymerization ratio of styrene and butadiene as the binder of the negative electrode is 1
It is described to use a styrene-butadiene copolymer having a ratio of 00 to 30 to 100.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide a paste type electrode in which a fluororesin is uniformly dispersed in a paste and the adhesion between an active material and a current collector is improved. is there.

Another object of the present invention is to provide a high-capacity alkaline secondary battery having an electrode in which a fluororesin is uniformly dispersed in a paste and the adhesion between an active material and a current collector is improved. Is to

It is an object of the present invention to avoid an internal short circuit during assembly in a battery having a spiral electrode group, and to improve the adhesion between the paste and the current collector and the winding property of the paste electrode. Is to provide.

Further, the object of the present invention is to improve the winding property of the electrode, to prevent the active material from falling off when manufacturing the spirally wound electrode group, and to prevent an internal short circuit during battery assembly. It is intended to provide an alkaline secondary battery in which an increase in internal pressure during charging is suppressed.

Further, an object of the present invention is to provide a paste type negative electrode in which polytetrafluoroethylene is uniformly dispersed and the adhesion between the hydrogen storage alloy and the current collector and the oxygen gas absorption performance during overcharge are improved. Another object of the present invention is to provide an alkaline secondary battery having a high capacity and a long life, which suppresses an increase in internal pressure during overcharging, and a method for manufacturing an alkaline secondary battery.

[0017]

The paste-type electrode according to the present invention is a paste-type electrode having a constitution in which a paste containing an active material and a binder is held on a current collector, and the binder is an average particle size. It is characterized in that it contains particles containing a fluororesin as a main component and having a diameter of 0.2 μm or less.

In the alkaline secondary battery according to the present invention, the positive electrode having a structure in which the paste containing the active material and the binder is held on the current collector and the paste containing the active material and the binder in the current collector are held. The negative electrode having the constitution and an alkaline electrolyte are provided, and the binder of the positive electrode and / or the negative electrode has an average particle size of 0.
It is characterized by containing particles having a fluororesin of 2 μm or less as a main component.

The paste-type electrode according to the present invention is a paste-type electrode having a structure in which a paste containing an active material and a binder is held on a current collector, and the binder has an average particle size of 0.2.
The current collector is a punched metal having particles having a particle size of μm or less as a main component and having a non-perforated region on at least one end orthogonal to the longitudinal direction, and the current collector is opened to the punched metal. The hole is oblong and has a major axis in the longitudinal direction of the punched metal.

The paste-type electrode according to the present invention is a paste-type electrode having a structure in which a paste containing an active material and a binder is held on a current collector, and the binder has an average particle size of 0.2.
The current collector includes particles having a fluororesin of not more than μm as a main component, and the current collector has a Vickers hardness of 40 to 100 H in which a non-porous region is formed on at least one end orthogonal to the longitudinal direction.
It is characterized by being made of v punched metal.

The alkaline secondary battery according to the present invention has a spirally wound electrode with a separator interposed between a negative electrode and a positive electrode having a structure in which a paste containing an active material and a binder is held on a current collector. A group; an alkaline electrolyte; the binder includes particles having a mean particle size of 0.2 μm or less as a main component of a fluororesin, and the current collector of the negative electrode has a winding start end and a winding end end. A punched metal in which a non-perforated region is formed at least at an end facing the positive electrode, the hole opened in the punched metal is oval, and is formed in the winding direction of the negative electrode. It is characterized by having a major axis.

In the alkaline secondary battery according to the present invention, the positive electrode having a structure in which the paste containing the active material and the binder is held on the current collector, and the paste containing the active material and the binder in the current collector are held. An electrode group formed by spirally winding a negative electrode having a structure with a separator interposed therebetween; an alkaline electrolyte; and at least the negative electrode binder having an average particle size of 0.2 μm or less. Of the positive electrode current collector, and the current collector of the positive electrode is a punched product in which a non-porous region is formed at least at an end of the winding start end and the winding end end facing the negative electrode. In the metal, the hole opened in the punched metal has an oval shape and has a major axis in the winding direction of the positive electrode, and the current collector of the negative electrode has a winding start end and a winding end. At least the end portion facing the positive electrode has a non-porous region. A made a punched metal, the punched metal in the opened pores is characterized in that it has a major diameter oval, and the winding direction of the negative electrode.

The alkaline secondary battery according to the present invention is a spirally wound electrode having a separator interposed between a negative electrode and a positive electrode having a structure in which a paste containing an active material and a binder is held on a current collector. A group; an alkaline electrolyte; the binder contains particles having an average particle diameter of 0.2 μm or less as a main component of a fluororesin, and the negative electrode current collector has a winding start end and a winding end. The Vickers hardness is 40 to 10 in which a non-hole region is formed in at least the end of the end facing the positive electrode.
It is characterized by being made of punched metal of 0 Hv.

In the alkaline secondary battery according to the present invention, the positive electrode having a structure in which the paste containing the active material and the binder is held on the current collector, and the paste containing the active material and the binder in the current collector are held. An electrode group formed by spirally winding a negative electrode having a structure with a separator interposed therebetween; an alkaline electrolyte; and at least the negative electrode binder having an average particle size of 0.2 μm or less. The current collector of the positive electrode comprises particles having a fluororesin as a main component, and a Vickers in which a non-porous region is formed at least at an end of the winding start end and the winding end end facing the negative electrode. Hardness is 40-100Hv
The negative electrode current collector is made of a punched metal, and has a Vickers hardness of 40 to 100 Hv in which a non-hole region is formed at least at an end of the winding start end and the winding end end facing the positive electrode. It is characterized by being made of punched metal.

In the alkaline secondary battery according to the present invention, the positive electrode having a structure in which the paste containing the active material and the binder is held on the current collector, and the paste containing the active material and the binder in the current collector are held. An electrode group formed by spirally winding a negative electrode having a structure with a separator interposed therebetween; an alkaline electrolyte; and at least the negative electrode binder having an average particle size of 0.2 μm or less. The current collector of the positive electrode comprises particles having a fluororesin as a main component, and a Vickers in which a non-porous region is formed at least at an end of the winding start end and the winding end end facing the negative electrode. Hardness is 40-100Hv
The current collector of the negative electrode is a punched metal in which a non-porous region is formed at least at the end facing the positive electrode of the winding start end and the winding end, The hole opened in the punched metal has an oval shape and has a major axis in the winding direction of the negative electrode.

In the alkaline secondary battery according to the present invention, the positive electrode having a structure in which the paste containing the active material and the binder is held on the current collector, and the paste containing the active material and the binder in the current collector are held. An electrode group formed by spirally winding a negative electrode having a structure with a separator interposed therebetween; an alkaline electrolyte; and at least the negative electrode binder having an average particle size of 0.2 μm or less. Of the positive electrode current collector, and the current collector of the positive electrode is a punched product in which a non-porous region is formed at least at an end of the winding start end and the winding end end facing the negative electrode. The hole formed in the punched metal, which is a metal, has an elliptical shape and has a major axis in the winding direction of the positive electrode, and the current collector of the negative electrode has a winding start end and a winding end end. A non-porous region at least at the end facing the positive electrode Vickers hardness is formed 40
It is characterized by being made of punched metal of about 100 Hv.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION An alkaline secondary battery according to the present invention collects a positive electrode configured to hold a paste containing an active material and a binder on a current collector, and a paste containing the active material and a binder. A negative electrode configured to be held by the body, and an alkaline electrolyte, and the binder for the positive electrode and / or the negative electrode contains particles containing a fluororesin as a main component and having an average particle size of 0.2 μm or less. It is a feature.

Hereinafter, the alkaline secondary battery according to the present invention will be described in detail with reference to FIG.

An electrode group 5 made by stacking a positive electrode 2, a separator 3 and a negative electrode 4 and spirally winding them is housed in a bottomed cylindrical container 1. The negative electrode 4 is arranged at the outermost periphery of the electrode group 5 and is in electrical contact with the container 1. The alkaline electrolyte is contained in the container 1. A circular first sealing plate 7 having a hole 6 in the center is arranged at the upper opening of the container 1. The ring-shaped insulating gasket 8 is
Is arranged between the periphery of the container and the inner surface of the upper opening of the container 1,
The sealing plate 7 is airtightly fixed to the container 1 via the gasket 8 by caulking to reduce the diameter of the upper opening inward. One end of the positive electrode lead 9 is connected to the positive electrode 2, and the other end is connected to the lower surface of the sealing plate 7. The positive electrode terminal 10 having a hat shape is attached on the sealing plate 7 so as to cover the hole 6. Rubber safety valve 1
1 is arranged so as to close the hole 6 in a space surrounded by the sealing plate 7 and the positive electrode terminal 10. A circular holding plate 12 made of an insulating material having a hole in the center is provided on the positive electrode terminal 10 so that a protrusion of the positive electrode terminal 10 is provided on the holding plate 1.
2 so as to protrude from the holes. The outer tube 13 covers the periphery of the holding plate 12, the side surface of the container 1, and the periphery of the bottom of the container 1.

Hereinafter, the negative electrode 4, the positive electrode 2 and the separator 3 will be described.
The alkaline electrolyte will be described in detail.

(1) Negative Electrode 4 As the negative electrode 4, the following two types of negative electrodes can be used.

<First Negative Electrode> The negative electrode has a structure in which a paste containing an active material and a binder is held or supported on a current collector. The binder has an average particle size of 0.2 μm.
The particles containing the following fluororesin as a main component are included.

Examples of the active material include cadmium compounds such as metal cadmium and cadmium hydroxide, hydrogen and the like. Examples of the hydrogen host matrix include a hydrogen storage alloy.

Among them, the hydrogen storage alloy is preferable because it can improve the capacity of the secondary battery as compared with the case of using the cadmium compound. As the hydrogen storage alloy, it can be used, for example AB ₅ type, A ₂ B type, AB-type, all alloys called as _Type AB. However, RNi
_5-xy Co _x A _y (wherein R is at least one element selected from rare earth elements including La and Y or misch metal, A is Al, Mn, Ti, Cu, Zn, Zr, C
It is preferable to use a hydrogen storage alloy represented by at least one selected from r, and x and y have atomic ratios of x ≧ 0.4 and 0 ≦ y ≦ 2.0, respectively.

Examples of the particles containing the fluororesin as a main component include particles containing polytetrafluoroethylene as a main component and particles containing a tetrafluoroethylene-hexafluoropropylene copolymer as a main component. Among the particles containing polytetrafluoroethylene as a main component, unfired particles are preferable because shearing stress (shear) causes fiberization to occur and the strength of the negative electrode can be improved.

The average particle size of the particles containing the fluororesin as a main component is measured by the following method. That is, using a scanning electron microscope, for primary particles in the visual field, the maximum diameter of the diameters along a certain direction was measured, and the 50% by weight average calculated by regarding the primary particles as a true sphere having the maximum diameter as a diameter. The particle size is the average particle size of the particles containing the fluororesin as a main component.

If the average particle size exceeds 0.2 μm, the dispersibility in the paste is poor, and therefore the adhesion between the active material and the current collector and the gas absorption performance of the negative electrode may deteriorate. The smaller the particle size, the better the dispersibility, which is preferable.

The above-mentioned non-calcined polytetrafluoroethylene-based particles having an average particle size of 0.2 μm or less preferably have a standard specific gravity (SSG) in the range of 2.1 to 2.3. . The standard specific gravity refers to the specific gravity of a tetrafluoroethylene molded product obtained under the molding and firing conditions defined in JIS D ASTM D1457. As the standard specific gravity decreases, the polytetrafluoroethylene particles tend to have a low molecular weight and a low degree of fiber formation. Polytetrafluoroethylene having a standard specific gravity of 2.1 or less causes a significant decrease in the degree of fiberization, and thus the adhesiveness between the paste and the current collector may decrease. On the other hand, it is difficult to manufacture the particles having the average particle diameter of 0.2 μm or less from the polytetrafluoroethylene having the standard specific gravity of more than 2.3 by the present technology. Further, if polytetrafluoroethylene having a standard specific gravity of more than 2.3 is used, the production cost may increase. More preferably, the average particle size is in the range of 0.05 to 0.15 μm, and the standard specific gravity is in the range of 2.15 to 2.25.

The binder may be formed only of particles having a mean particle size of 0.2 μm or less and containing a fluororesin as a main component, but may contain other polymer.

Examples of the polymer used in combination with the fluororesin particles include polyethylene, polypropylene, rubber polymers (for example, latex of polypropylene styrene butadiene rubber (SBR), latex of acrylonitrile butadiene rubber (NBR), ethylene propylene diene monomer (EPDM). ) Latex, etc.); carboxymethylcellulose (CMC), methylcellulose (MC), hydroxypropylmethylcellulose (HPMC), polyacrylates (eg sodium polyacrylate (SPA)), polyvinyl alcohol (PVA), Polyethylene oxide, copolymer of acrylic acid and vinyl alcohol, copolymer of acrylic acid salt and vinyl alcohol, copolymer of maleic acid and vinyl alcohol, etc. Hydrophilic polymer; and the like. The polyethylene and polypropylene can be used in the form of dispersion.

The amount of the particles containing the fluororesin as the main component and having the average particle diameter within the above range is such that the hydrogen storage alloy 100 is added.
It is preferably in the range of 0.5 to 5.0 parts by weight with respect to parts by weight. When the addition amount is less than 0.5 parts by weight,
It may become difficult to improve the adhesion between the hydrogen storage alloy and the current collector and the gas absorption performance of the negative electrode. On the other hand, when the amount added exceeds 5.0 parts by weight, the amount of hydrogen storage alloy contained in the paste is reduced, which may reduce the negative electrode capacity. A more preferable amount of addition is 100 hydrogen storage alloys.
It is in the range of 1.0 to 3.0 parts by weight with respect to parts by weight.

The polymer used in combination with the fluororesin particles is 0.5 to 5 with respect to 100 parts by weight of the hydrogen storage alloy.
It is preferable that the compounding agent be added in a weight ratio (more preferably 1.0 to 3.0 weight parts).

The current collector has a two-dimensional structure such as punched metal, expanded metal, or wire mesh,
Examples thereof include those having a three-dimensional structure such as foamed metal and reticulated sintered metal fiber.

For the negative electrode, for example, an active material (host matrix of the active material), a conductive material, a binder and water are kneaded to prepare a paste, the current collector is filled or coated, and dried. After that, it can be manufactured by molding. The particles containing the fluororesin as a main component can be added to the paste in the form of dispersion.

Examples of the conductive material include carbon black and graphite. Such a conductive material is used in an amount of 0.1 to 4 with respect to 100 parts by weight of the hydrogen storage alloy.
It is preferable to mix in the range of parts by weight.

<Second Negative Electrode> This negative electrode is the same as the above-mentioned first negative electrode except that the binder does not contain particles having an average particle size of 0.2 μm or less as a main component of fluororesin. It has a similar configuration.

(2) Positive Electrode 2 As the positive electrode 2, the following two types of positive electrodes can be used.

<First Positive Electrode> The positive electrode has a structure in which a paste containing an active material and a binder is held or carried on a current collector. The binder has an average particle size of 0.2 μm.
The particles containing the following fluororesin as a main component are included.

Examples of the active material include nickel hydroxide particles.

The nickel hydroxide particles preferably have a spherical shape or a shape similar thereto.

The nickel hydroxide particles have an average particle size of 5
Preferably, the tap density is ˜30 μm and the tap density is 1.8 g / cm ³ or more.

The nickel hydroxide particles have a specific surface area of 8
It is preferably ˜25 m ² / g.

As the particles containing a fluororesin as a binder as a main component, the same particles as those described for the first negative electrode can be used.

The average particle size of the particles containing the fluororesin as the main component is measured by the same method as described for the first negative electrode.

The average particle size is set to 0.2 μm or less for the same reason as described above for the first negative electrode.

The above-mentioned particles containing polytetrafluoroethylene as a main component which has not been fired and has an average particle size of 0.2 μm or less have a standard specific gravity (SSG) for the same reason as explained in the above-mentioned first negative electrode. Is preferably in the range of 2.1 to 2.3. More preferably, the average particle size is 0.0
In the range of 5 to 0.15 μm, and the standard specific gravity is 2.15 to
The particles are in the range of 2.25.

The binder may be formed only of particles containing fluororesin as the main component and having an average particle diameter of 0.2 μm or less, but may contain other polymer.

As the polymer used in combination with the fluororesin particles, the same polymers as described for the above-mentioned first negative electrode can be mentioned.

The amount of the particles containing the fluororesin as the main component having the average particle diameter in the above range is 10% by weight of the nickel hydroxide.
It is preferably in the range of 0.5 to 5.0 parts by weight with respect to 0 parts by weight. If the amount added is less than 0.5 part by weight, it may be difficult to improve the adhesion between the nickel hydroxide and the current collector. On the other hand, if the addition amount exceeds 5.0 parts by weight, the amount of nickel hydroxide in the positive electrode is reduced, which may reduce the capacity of the positive electrode. A more preferable addition amount is 1.
It is in the range of 0 to 4.0 parts by weight.

The combined polymer is preferably added in an amount of 0.2 to 5.0 parts by weight (more preferably 0.3 to 2.0 parts by weight) with respect to 100 parts by weight of the nickel hydroxide.

Examples of the current collector include sponge-like metal porous bodies and metal fiber mats.

For the positive electrode, for example, a paste containing nickel hydroxide powder, a conductive agent, a binder and water is prepared,
It is prepared by filling or coating the current collector with the paste, drying and press-molding the paste, and then cutting the paste into a desired size.

Examples of the conductive agent include cobalt compounds such as cobalt monoxide, dicobalt trioxide and cobalt hydroxide, and metallic cobalt. The amount of such a conductive agent added is preferably in the range of 5 to 10 parts by weight with respect to 100 parts by weight of the nickel hydroxide.

<Second Positive Electrode> This positive electrode is the same as the above-mentioned first positive electrode except that the binder does not contain particles having an average particle size of 0.2 μm or less as a main component of fluororesin. It has a similar configuration.

(3) Separator 3 Examples of the separator 3 include a nonwoven fabric made of polyolefin fiber, a nonwoven fabric made of nylon fiber, a nonwoven fabric made by mixing polyolefin fiber and nylon fiber, and the like. In particular, a nonwoven fabric made of polyolefin fiber whose surface is hydrophilized is suitable as the separator 3. The separator 3 preferably has a thickness of 100 to 200 μm.

(4) Alkaline Electrolyte As the alkaline electrolyte, for example, a mixed solution of sodium hydroxide (NaOH) and lithium hydroxide (LiOH),
A mixture of potassium hydroxide (KOH) and LiOH, or N
A mixed solution of aOH, KOH, and LiOH can be used.

The alkaline secondary battery according to the present invention comprises a positive electrode of one of the above-mentioned two kinds of positive electrodes and a negative electrode of either one of the above-mentioned two kinds of negative electrodes. . However, the secondary battery does not have the above-described configuration including the second positive electrode and the second negative electrode.

In FIG. 1 described above, the separator 3 was interposed between the negative electrode 4 and the positive electrode 2 and wound in a spiral shape and housed in the cylindrical container 1 having a bottom. A separator may be interposed between them to form a laminated body, and the laminated body may be housed in a rectangular tubular container with a bottom.

The second alkaline secondary battery according to the present invention is
A separator is interposed between one of the two types of negative electrodes A and B described below and a positive electrode selected from the four types of positive electrodes described below and the above-described first and second positive electrodes, and this is swirled. An electrode group formed by winding the electrode in a circular shape; an alkaline electrolyte;

The second alkaline secondary battery according to the present invention is
For example, the cylindrical structure shown in FIG. 1 can be used.

In the electrode group, the winding start end portion of the negative electrode faces the winding start end portion or the side surface of the positive electrode through the separator, or the winding end end portion of the negative electrode through the separator. Or a structure in which the winding start end of the negative electrode faces the winding start end or side of the positive electrode through the separator, and the winding end of the negative electrode is the separator. It is advisable to adopt a structure that faces the winding end portion or the side surface of the positive electrode via the interposition.

Among them, the electrode group preferably has a structure in which the winding start end of the negative electrode faces the side surface of the positive electrode via the separator. As such an electrode group, for example, the one as shown in FIG. 2 can be cited. That is, the S-shaped separator 3 is arranged on the inner circumference of the electrode group 5. The positive electrode 2 is arranged outside the S-shaped separator 3. A winding start end portion 4 a of the negative electrode 4 is arranged between the S-shaped separator 3 and the side surface of the positive electrode 2 with another separator 3 interposed therebetween. The circumferential angle (θ) formed by the winding start end 2a of the positive electrode 2 and the winding start end 4a of the negative electrode 4 is 90 °. Thus, the electrode group having a structure in which the positive electrode 2 is wound before the negative electrode 4 is an advantageous structure for increasing the capacity of the alkaline secondary battery.

Further, as the electrode group 5, it is also possible to use one having a central portion of a structure in which the peripheral angle (θ) is 180 ° as shown in FIG.

In the electrode group having a structure in which the winding start end of the negative electrode faces the inner surface of the positive electrode on the inner circumference again as shown in FIGS. 2 and 3, the winding start end of the positive electrode and the negative electrode are arranged. The circumferential angle (θ) corresponding to the positional deviation from the winding start end is preferably 60 ° to 210 °.
This is due to the following reasons. If the circumferential angle is less than 60 °, it may be difficult to sufficiently increase the capacity of the alkaline secondary battery. The circumferential angle is 21
If it exceeds 0 °, the proportion of the portion of the positive electrode that is not involved in the battery reaction may increase, which may cause inconvenience in battery design. A more preferable circumferential angle (θ) is 9
It is in the range of 0 ° to 180.

Hereinafter, the negative electrode and the positive electrode will be described in detail. The separator and the alkaline electrolyte may be the same as those described for the first alkaline secondary battery described above.

(1) Negative Electrode As the negative electrode, the following two types of negative electrodes can be used.

<Negative Electrode A> The negative electrode A has a structure in which a paste containing an active material and a binder is held or supported on a current collector. The binder contains particles having an average particle diameter of 0.2 μm or less and a fluororesin as a main component. The current collector is a punched metal in which a hole has an oval shape, and a non-perforated region is formed in at least an end of the winding start end and the winding end end facing the positive electrode, and The oblong hole has a major axis in the winding direction of the negative electrode.

As the active material and the binder, the same ones as described for the first negative electrode can be used.

In the current collector, the ratio of the major axis to the minor axis of the elliptical hole serves as an index of the roller pressing degree. The ratio of the major axis to the minor axis of the oblong hole is 1.01 to
It is preferably in the range of 1.50. The ratio is 1.0
A negative electrode having a ratio of less than 1 has an insufficient degree of pressurization, and it may be difficult to sufficiently improve flexibility, active material packing density, and active material holding power of the current collector. On the other hand, a negative electrode having a ratio exceeding 1.50 may be over-pressurized at the time of roller pressing, and the current collector may be broken or the active material may drop off. A more preferable ratio of the major axis to the minor axis of the oblong hole is in the range of 1.05 to 1.20.

The thickness of the current collector is 10 to 100 μm.
(More preferably 20 to 80 μm).

The aperture ratio of the current collector is preferably in the range of 30 to 70% (more preferably 40 to 65%).

The negative electrode A can be produced, for example, by the method described below. That is, an active material (host matrix of the active material), a binder and a conductive agent are kneaded in the presence of water to prepare a paste. The paste is filled or applied to a punched metal in which the shape of the hole is circular and at least one end portion orthogonal to the longitudinal direction has a non-perforated region. Continue to dry this,
The negative electrode A can be produced by performing a roller press so that the circular hole extends in the longitudinal direction of the punched metal and is deformed into an oval shape. Such a negative electrode
Since winding can be easily performed with the direction orthogonal to the longitudinal direction as an axis, it is possible to avoid cracks during the production of the spiral electrode group and dropping of the active material.

<Negative Electrode B> The negative electrode B has a structure in which a paste containing an active material and a binder is held or carried on a current collector. The binder contains particles having an average particle diameter of 0.2 μm or less and a fluororesin as a main component. The current collector is made of punched metal having a Vickers hardness of 40 to 100 Hv in which a non-hole region is formed on at least one end portion orthogonal to the longitudinal direction.

As the active material and the binder, the same ones as described for the first negative electrode can be used.

The reason why the Vickers hardness of the current collector is limited to the above range is as follows. If the Vickers hardness is less than 40 Hv, the current collector may extend too much during roller pressing, and the electrode density may decrease. On the other hand, if the Vickers hardness exceeds 100 Hv, the flexibility of the current collector is lowered, so that cracks or drop of the active material may occur when producing the spiral electrode group. Moreover, since the positive electrode and the negative electrode do not completely adhere to each other via the separator during winding, the effective reaction area may decrease. More preferable Vickers hardness is 50 to 8
It is in the range of 0 Hv.

The thickness of the current collector is 10 to 100 μm.
(More preferably 20 to 80 μm).

The aperture ratio of the current collector is preferably in the range of 30 to 70% (more preferably 40 to 65%).

For the negative electrode B, for example, an active material (host matrix of the active material), a binder and a conductive agent are kneaded in the presence of water to prepare a paste, and the paste is filled in the current collector or It can be produced by coating, drying, and roller pressing.

The two types of negative electrodes A and B described above may be covered with an auxiliary separator in which at least one of the winding start end and the winding end is opposed to the positive electrode and is folded in two.

Examples of the auxiliary separator include those made of non-woven fabric made of polyolefin fiber, non-woven fabric made of nylon fiber, non-woven fabric made by mixing polyolefin fiber and nylon fiber, and the like. Examples of the polyolefin fibers include polypropylene fibers and polyethylene fibers. The surface of the polyolefin fiber is preferably hydrophilized.

(2) Positive Electrode As the positive electrode, four types of positive electrodes described below can be used.

<Positive Electrode A> The positive electrode A has a structure in which a paste containing an active material and a binder is carried or held on a current collector. The binder contains particles having an average particle diameter of 0.2 μm or less and a fluororesin as a main component. The current collector is a punched metal in which holes have an oval shape and a non-hole region is formed at at least one end portion orthogonal to the longitudinal direction. The hole has a major axis in the longitudinal direction of the current collector.

As the active material and the binder, the same ones as described for the above-mentioned first positive electrode can be mentioned.

In the current collector, the ratio of the major axis to the minor axis of the elliptical hole serves as an index of the roller pressing degree. The ratio of the major axis to the minor axis of the oblong hole is 1.01 to
It is preferably in the range of 1.50. The ratio is 1.0
If it is less than 1, the degree of pressurization of the positive electrode is insufficient,
It may be difficult to sufficiently improve the flexibility of the positive electrode, the packing density of the active material, and the holding power of the current collector for the active material. On the other hand, if the ratio exceeds 1.50, the roller may be over-pressed at the time of roller pressing, and the current collector may be broken or the active material may fall off. More preferable ratio of the major axis to the minor axis of the oblong hole is 1.05 to 1.20.
Range.

The thickness of the current collector is 10 to 100 μm.
(More preferably 20 to 80 μm).

The aperture ratio of the current collector is preferably in the range of 30 to 70% (more preferably 40 to 65%).

The positive electrode A can be produced, for example, by the method described below. That is, the active material,
A paste containing a binder and a conductive agent is prepared, and the paste is filled or coated with a punched metal having a circular hole shape and having a non-perforated region formed on at least one end orthogonal to the longitudinal direction. . The positive electrode A is manufactured by drying this and applying a roller press so that the circular hole extends in the longitudinal direction of the punched metal and is deformed into an oval shape. Since such a positive electrode can be easily wound around a direction orthogonal to the longitudinal direction as an axis, it is possible to avoid cracks during the production of the spiral electrode group and dropping of the active material.

As the conductive agent, the same ones as described for the first positive electrode can be used.

<Positive Electrode B> The positive electrode B has the same structure as that of the positive electrode A described above except that the binder does not include particles containing a fluororesin having an average particle diameter of 0.2 μm or less as a main component.

<Positive Electrode C> The positive electrode C has a structure in which a paste containing an active material and a binder is carried or held on a current collector. The binder contains particles having an average particle diameter of 0.2 μm or less and a fluororesin as a main component. The current collector is formed of a punched metal having a Vickers hardness of 40 to 100 Hv in which a non-perforated region is formed on at least one end portion orthogonal to the longitudinal direction.

As the active material and the binder, the same ones as described for the above-mentioned first positive electrode can be mentioned.

The reason why the Vickers hardness of the current collector is limited to the above range is as follows. If the Vickers hardness is less than 40 Hv, the current collector may extend too much during roller pressing, and the electrode density may decrease. On the other hand, if the Vickers hardness exceeds 100 Hv, the flexibility of the current collector is lowered, so that cracks or drop of the active material may occur when producing the spiral electrode group. Moreover, since the positive electrode and the negative electrode do not completely adhere to each other via the separator during winding, the effective reaction area may decrease. More preferable Vickers hardness is 50 to
It is in the range of 80 Hv.

The thickness of the current collector is 10 to 100 μm.
(More preferably 20 to 80 μm).

The aperture ratio of the current collector is preferably in the range of 30 to 70% (more preferably 40 to 65%).

For the positive electrode C, for example, an active material, a binder and a conductive agent are kneaded in the presence of water to prepare a paste, and the paste is filled or coated on the current collector and then dried. It can be manufactured by applying a roller press.

As the conductive agent, the same ones as described for the first positive electrode can be used.

<Positive Electrode D> The positive electrode D has the same structure as that of the positive electrode C described above except that the binder does not include particles containing a fluororesin having an average particle diameter of 0.2 μm or less as a main component.

The four types of positive electrodes A to D described above may be covered with an auxiliary separator in which at least one of the winding start end and the winding end is opposed to the negative electrode and is folded in two.

As the auxiliary separator, the same ones as described above can be mentioned. A third alkaline secondary battery according to the present invention is a paste-type negative electrode containing a hydrogen storage alloy, polytetrafluoroethylene, and 0.01 to 1.0 parts by weight of a surfactant with respect to 100 parts by weight of the hydrogen storage alloy. And a positive electrode and an alkaline electrolyte.

Such an alkaline secondary battery can have the cylindrical structure shown in FIG. 1 described above. Alternatively, a separator may be interposed between each of the plurality of negative electrodes and each of the plurality of positive electrodes to form a laminated body, and the laminated body may be housed in a bottomed rectangular tubular container to have a rectangular structure.

As the separator and the alkaline electrolyte of the alkaline secondary battery, the same ones as described in the above-mentioned first alkaline secondary battery can be mentioned.

The paste type negative electrode and the positive electrode will be described below.

(1) Paste-Type Negative Electrode The paste-type negative electrode is, for example, as follows (I) to (III
).

(I) Hydrogen-absorbing alloy powder, a binder containing a dispersion of unburned polytetrafluoroethylene particles and a conductive material are kneaded in the presence of water to prepare a paste, and then the paste is collected. The negative electrode is manufactured by filling or coating with an electric body, drying and press-molding.

(II) After the hydrogen-absorbing alloy powder, the conductive material and the hydrophilic polymer are kneaded in the presence of water, an aqueous solution of a surfactant is added and kneaded, and the unburned polytetrafluoroethylene particles are mixed. A paste is prepared by adding and kneading the mixture, and the paste is filled or coated on a current collector, dried, and pressure-molded to produce the negative electrode.

(III) By kneading the hydrogen storage alloy powder, the conductive material and the hydrophilic polymer in the presence of water, an aqueous solution of a surfactant and unfired polytetrafluoroethylene particles are added and kneaded. After preparing a paste, filling or coating the paste on a current collector, it is dried and pressure-molded to produce the negative electrode.

As the hydrogen storage alloy powder, the conductive material, and the current collector, the same ones as described for the above-mentioned first negative electrode can be used.

The binder may be formed only from unburned polytetrafluoroethylene particles, but may contain other polymer such as hydrophilic polymer.
As the polymer used in combination with the polytetrafluoroethylene particles, the same polymers as described in the first negative electrode can be mentioned.

From the viewpoint of improving the dispersibility of the polytetrafluoroethylene particles in the paste, the average particle size of the polytetrafluoroethylene particles is preferably 0.2 μm or less. The lower limit of the particle size is preferably 0.01 μm, and the more preferred particle size is 0.05 to 0.1.
The range is 5 μm. The average particle size is measured in the same manner as described above.

The unburned polytetrafluoroethylene particles having a particle size within the above range preferably have a standard specific gravity (SSG) of 2.1 to 2.3 for the same reason as described above. More preferable standard specific gravity is 2.15
The range is from 2.25 to 2.25.

The amount of the polytetrafluoroethylene particles added is preferably in the range of 0.5 to 5.0 parts by weight based on 100 parts by weight of the hydrogen storage alloy for the same reason as described above. A more preferable amount of addition is in the range of 1.0 to 3.0 parts by weight with respect to 100 parts by weight of the hydrogen storage alloy.

The polymer used in combination with the polytetrafluoroethylene particles is 0.5 to 5 parts by weight (more preferably 1.0 to 3.0 parts by weight) based on 100 parts by weight of the hydrogen storage alloy.
(Parts by weight) is preferred.

Examples of the surfactant contained in the paste include nonionic surfactants, anionic surfactants, cationic surfactants and amphoteric surfactants.

The reason why the content of the surfactant is limited to the above range is as follows. When the content is less than 0.01 parts by weight based on 100 parts by weight of the hydrogen storage alloy, it may be difficult to uniformly disperse the polytetrafluoroethylene particles in the paste. On the other hand, when the content exceeds 100 parts by weight with respect to 100 parts by weight of the hydrogen-absorbing alloy, the wettability of the negative electrode increases, so that the water repellency of the negative electrode decreases,
There is a risk that the three-phase interface amount will be insufficient. A more preferable content is in the range of 0.03 part by weight to 0.5 part by weight.

(2) Positive Electrode The positive electrode may be the above-mentioned first positive electrode or the second positive electrode.
Can be used.

The first alkaline secondary battery according to the present invention described in detail above collects a paste containing a binder and an active material containing particles containing fluororesin as the main component and having an average particle size of 0.2 μm or less. A first positive electrode configured to be held by an electric body is provided.
The above-mentioned fluororesin particles have a particle size of 0.
The specific surface area is higher than that of polytetrafluoroethylene particles of 4 μm or more, and the particles can be uniformly dispersed in the paste of the positive electrode. Therefore, the adhesion between the active material and the current collector can be dramatically improved, and the active material can be prevented from falling off during battery assembly or during charge / discharge cycles. Further, since the amount of the binder used can be reduced (for example, 40 to 70% of the conventional amount used),
The amount of active material in the positive electrode can be increased, and the active material density of the positive electrode can be improved. As a result, since the capacity of the positive electrode can be improved, it is possible to provide an alkaline secondary battery with greatly improved discharge capacity and cycle life.

Furthermore, since sufficient adhesion can be secured even with low-molecular-weight polytetrafluoroethylene having a low degree of fiberization, it is possible to increase the types of polytetrafluoroethylene that can be used (usable standard specific gravity). Can be expanded to 2.1 to 2.3), and the manufacturing cost of the paste positive electrode can be reduced.

In the first alkaline secondary battery according to the present invention, the paste containing the binder and the active material containing the particles containing the fluororesin as the main component and having the average particle diameter of 0.2 μm or less is used as the current collector. And a first negative electrode configured to be retained by the first negative electrode. Since the fluororesin particles can improve the specific surface area and can be uniformly dispersed in the paste of the negative electrode, the adhesion between the active material and the current collector and the density of the active material of the negative electrode can be improved. be able to. As a result, the capacity of the negative electrode can be improved, so that it is possible to provide an alkaline secondary battery with greatly improved discharge capacity and cycle life.

Further, since the negative electrode is provided with water repellency uniformly by the fluororesin particles, it is possible to form a three-phase interface uniformly on the whole and inevitably occur from the positive electrode during overcharge. Oxygen gas can be quickly absorbed. Therefore, the alkaline secondary battery including the negative electrode can suppress an increase in internal pressure during overcharge and improve the charge / discharge cycle life.

Furthermore, since the types of polytetrafluoroethylene that can be used can be increased, it is possible to reduce the manufacturing cost of the paste type negative electrode.

The first alkaline secondary battery according to the present invention is
It is provided with the above-mentioned first positive electrode and first negative electrode. In such a secondary battery, since the adhesion between the active material and the current collector and the energy density can be increased in both the positive electrode and the negative electrode, the discharge capacity can be improved. In addition, since the oxygen gas absorption performance of the negative electrode during overcharge can be improved, it is possible to suppress an increase in internal pressure during overcharge. Therefore, it becomes possible to provide an alkaline secondary battery with dramatically improved discharge capacity and charge / discharge cycle life.

The second alkaline secondary battery according to the present invention is
Spiral with a separator interposed between the negative electrode A and the positive electrode configured to hold the paste containing the binder and the active material containing the particles whose main particle diameter is 0.2 μm or less as the main component of the fluororesin on the current collector. It has an electrode group produced by winding it into a shape. The current collector of the negative electrode A is a punched metal having a non-perforated region at least at an end of the winding start end and the winding end end facing the positive electrode. The hole opened in the punched metal has an oval shape and has a long diameter in the winding direction of the negative electrode.

Since such a negative electrode uses a punched metal having a specific structure as a current collector and contains fluororesin particles having a specific average particle size as a binder, it has an active material packing density and an active material holding power. It is high and can be easily wound around the direction orthogonal to the longitudinal direction as an axis. Therefore, the negative electrode and the positive electrode can be wound in a state in which they are in close contact with each other via the separator, and it is possible to avoid a heterogeneous reaction caused by a decrease in the adhesion of the positive and negative electrodes. Also,
It is possible to prevent the active material from falling off during the production of the spiral electrode group or during the charge / discharge reaction. As a result, the discharge capacity of the secondary battery can be improved, and the cycle life can be improved. Furthermore, since the negative electrode can improve the oxygen gas absorption performance, the secondary battery can suppress an increase in internal pressure during overcharge.

Further, since the punched metal of the negative electrode has a non-perforated region formed at least at the end facing the positive electrode, the end is prevented from penetrating the separator and coming into contact with the positive electrode. be able to. Therefore, it is possible to avoid an internal short circuit when the electrode group is manufactured or when the electrode group is housed in a container with a high volume, and the yield can be improved.

Therefore, according to the present invention, in the alkaline secondary battery, there is a problem that occurs when the amount of the negative electrode active material charged is increased for the purpose of increasing the capacity, that is, the winding property of the negative electrode decreases. It is possible to eliminate the drop of the active material at the time of winding and the increase of the internal short circuit due to the increase of the volume of the electrode group housed in the container, thereby realizing a high capacity negative electrode and improving the discharge capacity. The cycle life can be improved by suppressing the increase in internal pressure during overcharge.

Further, the secondary battery can effectively prevent an internal short circuit that occurs when the electrode group is manufactured or when the electrode group is housed, as described above. Therefore, the winding start end of the negative electrode and the side surface of the positive electrode are separated by the separator. It is possible to use a spiral-shaped electrode group having a structure facing each other through. As a result, the advantage of the high capacity, which is a feature of the spiral electrode group, can be taken advantage of, so that the discharge capacity of the alkaline secondary battery can be dramatically improved.

That is, although the spiral electrode group having the above-mentioned structure has a high capacity, not only an internal short circuit easily occurs when it is housed in a container with a high volume, but also an internal short circuit easily occurs during a charge / discharge cycle. . In the alkaline secondary battery, the positive electrode swells as the charging / discharging cycle progresses, which shortens the distance between the positive electrode and the negative electrode. When needle-like metal caused by punched metal is present at the winding start end of the positive electrode when such swelling occurs, the needle-like metal penetrates the separator and contacts the negative electrode, causing an internal short circuit. . By forming a non-perforated region at least at the winding start end of the punched metal of the negative electrode as in the present invention, an internal short circuit due to the structure of the electrode group can be avoided.

Further, as the current collector of the positive electrode, an oval hole having a major axis in the specific direction is opened, and at least one end of the winding start end and the winding end end facing the negative electrode has no hole. By using the punched metal in which the region is formed, the active material filling amount can be increased as compared with the conventional punched metal, and the winding property is improved,
It is possible to prevent the active material from falling off during winding and to prevent an internal short circuit that occurs when the electrode group is housed in a container in a high volume. As a result, a high-capacity positive electrode can be realized, so that the alkaline secondary battery can be increased in capacity.

Further, by using as the binder for the positive electrode, a binder containing particles having an average particle size of 0.2 μm or less as a main component of fluororesin, the adhesion between the positive electrode material and the current collector is improved. Therefore, it is possible to enhance the effect of preventing the active material from falling off during winding. As a result, it is possible to provide an alkaline secondary battery with dramatically improved capacity and cycle characteristics.

The second alkaline secondary battery according to the present invention is
Spiral with a separator interposed between a negative electrode B and a positive electrode configured to hold a paste containing a binder containing particles containing a fluororesin as a main component having an average particle diameter of 0.2 μm or less and an active material on a current collector. It has an electrode group produced by winding it into a shape. The current collector of the negative electrode B is made of punched metal having a Vickers hardness of 40 to 100 Hv in which at least one of the winding start end and the winding end end facing the positive electrode has a non-porous region.

Since such a negative electrode is provided with the above-mentioned specific binder and current collector, it can be easily wound around the direction orthogonal to the longitudinal direction as an axis. Therefore, the negative electrode and the positive electrode can be wound in a state in which they are in close contact with each other via the separator, and it is possible to avoid a heterogeneous reaction caused by a decrease in the adhesion of the positive and negative electrodes. Further, the negative electrode can prevent the active material from falling off during the production of the electrode group. As a result, the discharge capacity of the secondary battery can be improved, and the cycle life can be improved. Furthermore, since the negative electrode can improve the oxygen gas absorption performance, the secondary battery can suppress an increase in internal pressure during overcharge.

By forming a non-hole region at least in the end of the punched metal of the negative electrode facing the positive electrode, it is possible to prevent the end from penetrating the separator and coming into contact with the positive electrode. Therefore, it is possible to avoid an internal short circuit when the electrode group is manufactured or when the electrode group is stored in a container with a high volume, and the yield can be improved.

Therefore, according to the present invention, in the alkaline secondary battery, there is a problem that occurs when the amount of the active material in the negative electrode is increased for the purpose of increasing the capacity, that is, the winding property of the negative electrode is deteriorated. It is possible to eliminate the drop of the active material during winding and the increase of internal short circuit due to the increase of the volume of the electrode group housed in the container, thereby realizing a high capacity negative electrode and improving the discharge capacity. The cycle life can be improved by suppressing the increase in internal pressure during overcharge.

Further, in the secondary battery, by using a spirally wound electrode group having a structure in which the winding start end of the negative electrode and the side surface of the positive electrode face each other with a separator interposed therebetween, the alkaline capacity in which the capacity is further increased is achieved. A secondary battery can be provided.

As the current collector of the positive electrode, a punched metal having a specific Vickers hardness in which at least one end of the winding start end and the winding end end facing the negative electrode is formed, and which has a specific Vickers hardness is used. The active material filling amount can be increased as compared with the conventional punched metal, the winding property is improved, the active material is prevented from falling off during winding, and the electrode group is housed in a container with a high volume. It is possible to prevent an internal short circuit that occurs during storage. Therefore, a high-capacity positive electrode can be realized, and the alkaline secondary battery can be increased in capacity.

Further, by using as the binder for the positive electrode, a binder containing particles having an average particle diameter of 0.2 μm or less as a main component of fluororesin, the adhesion between the positive electrode material and the current collector is improved. Therefore, it is possible to enhance the effect of preventing the active material from falling off during winding. As a result, it is possible to provide an alkaline secondary battery with dramatically improved capacity and cycle characteristics.

The second alkaline secondary battery according to the present invention is
The negative electrode A or the negative electrode B described above is used as the negative electrode, and one selected from the positive electrodes A to D described above is used as the positive electrode. Such an alkaline secondary battery can prevent the above-mentioned three problems, namely, deterioration of winding property, dropping of active material during winding, and internal short circuit due to increase in volume of electrode group, and The active material filling amount of the positive electrode and the negative electrode can be increased as compared with the conventional positive and negative electrodes including punched metal. As a result, the discharge capacity can be improved. In addition, since the negative electrode can improve the oxygen gas absorption performance, the charge / discharge cycle life of the secondary battery can be improved.

Further, in the secondary battery, by using a spiral electrode group having a structure in which the winding start end portion of the negative electrode and the side surface of the positive electrode face each other with the separator interposed therebetween, the alkaline capacity in which the capacity is further increased is used. A secondary battery can be provided.

The third alkaline secondary battery according to the present invention is
0.01 to 100 parts by weight of the positive electrode, hydrogen storage alloy, polytetrafluoroethylene, and the hydrogen storage alloy.
A paste type negative electrode including 1.0 part by weight of a surfactant and an alkaline electrolyte are provided. In such a negative electrode, polytetrafluoroethylene particles can be uniformly dispersed in the paste in the paste preparation process. As a result, the hydrogen storage alloy powder can be firmly held on the current collector, so that the hydrogen storage alloy powder can be prevented or prevented from falling off during battery assembly or during charge / discharge cycles. At the same time, since the three-phase interface can be formed uniformly and in a sufficient amount on the negative electrode, the oxygen gas absorption performance during overcharge of the negative electrode can be improved. Therefore, the alkaline secondary battery including the negative electrode can improve the capacity, suppress an increase in internal pressure during overcharge, and improve the charge / discharge cycle life.

In addition, in the method for producing an alkaline secondary battery according to the present invention, the hydrogen storage alloy, the conductive agent and the hydrophilic binder are kneaded in the presence of water, and then an aqueous surfactant solution is added and kneaded. Then, a negative electrode is produced by a method including a step of preparing a paste by further adding non-baked polytetrafluoroethylene particles and kneading, and a step of filling or coating the paste with a current collector. According to such a method, the particles can be uniformly dispersed in the paste without adding the polytetrafluoroethylene particles in the form of dispersion in the paste preparation step. As a result, it is possible to prevent the additive such as an alkaline component in the dispersion from remaining on the negative electrode, so that the hydrogen storage alloy is firmly held on the current collector, and oxygen during overcharge is retained. It is possible to provide a high-capacity, long-life alkaline secondary battery including a negative electrode having excellent gas absorption performance and containing no impurities.

Furthermore, in another method for producing an alkaline secondary battery according to the present invention, a hydrogen storage alloy, a conductive agent and a hydrophilic binder are kneaded in the presence of water, and then a surfactant aqueous solution and firing are performed. A negative electrode is manufactured by a method including a step of preparing a paste by adding unmixed polytetrafluoroethylene particles and kneading, and a step of filling or coating the paste with a current collector. According to such a method, the particles can be uniformly dispersed in the paste without adding the polytetrafluoroethylene particles in the form of dispersion in the paste preparation step. As a result, it is possible to prevent the additive such as an alkaline component in the dispersion from remaining on the negative electrode, so that the hydrogen storage alloy is firmly held on the current collector, and oxygen during overcharge is retained. It has a high gas absorption performance and a high capacity with a negative electrode containing no impurities.
A long-life alkaline secondary battery can be provided.

[0152]

Embodiments of the present invention will now be described in detail with reference to the drawings.

Example 1 <Preparation of Paste-type Positive Electrode> A mixed powder of 90 parts by weight of nickel hydroxide powder and 10 parts by weight of cobalt oxide powder was added to carboxymethylcellulose. 3 parts by weight and an average particle size of 0.
2.5 parts by weight of a suspension of 2 μm unburned polytetrafluoroethylene particles (standard specific gravity: 2.2) (specific gravity: 1.5, solid content: 60% by weight) in terms of solid content and polyacrylic acid 0.5 parts by weight was added, and 45 parts by weight of pure water was added and kneaded to prepare a paste.
Then, after filling this paste into a nickel-plated fiber substrate, further apply the paste to both surfaces thereof,
A paste type positive electrode was produced by drying, rolling with a roller press, and rolling. The average particle size of the polytetrafluoroethylene particles was measured by the method described above.

<Preparation of Paste Type Negative Electrode> Commercially available lanthanum-enriched misch metal Lm and Ni, Co, Mn,
LmNi _4.0 Co _0.4
A hydrogen storage alloy having a composition of Mn _0.3 Al _0.3 was produced. The hydrogen storage alloy was mechanically pulverized and passed through a 200-mesh sieve. 0.5 parts by weight of sodium polyacrylate based on 100 parts by weight of the obtained alloy powder,
0.125 parts by weight of carboxymethyl cellulose (CMC), a dispersion of non-calcined polytetrafluoroethylene particles (standard specific gravity is 2.2) having an average particle size of 0.4 μm (specific gravity 1.5, solid content 60 wt%) 2.5 parts by weight in terms of solid content and carbon powder as a conductive material 1.
By mixing 0 parts by weight with 50 parts by weight of water,
A paste was prepared. This paste was applied to punched metal, dried, and then roller pressed to produce a paste type negative electrode.

Next, a spirally wound electrode group was produced by interposing a separator made of a hydrophilic non-woven fabric of polyolefin fiber between the negative electrode and the positive electrode and spirally winding the separator. Such an electrode group and 7N KOH
A cylindrical nickel-hydrogen secondary battery having an AA size and a nominal capacity of 1200 mAh was assembled by accommodating an electrolytic solution consisting of 1N LiOH and a 1N LiOH in a cylindrical container having a bottom.

Comparative Example 1 A nickel-hydrogen secondary battery similar to that of Example 1 was assembled except that the average particle size of the polytetrafluoroethylene particles contained in the positive electrode was 0.4 μm.

With respect to the obtained positive electrodes of the secondary batteries of Example 1 and Comparative Example 1, the operation of spirally winding was repeated 5 times, and the positive electrodes were weighed so that the weight was larger than that before winding. The degree of dropout was measured by determining how much it had decreased. The results are shown in Table 1 below, assuming that the dropout degree of Comparative Example 1 is 100.

Further, with respect to the secondary batteries of Example 1 and Comparative Example 1, a charging / discharging cycle of charging 150% at 1 CmA and discharging at 1 CmA until the battery voltage reached 1.0 V was repeated. Then, the discharge capacity was calculated from the time until the battery voltage reached 1.0 V, and the number of cycles required until the discharge capacity decreased to 80% of the discharge capacity in the first cycle was obtained. The results are shown in Table 1 below. Write together.

[0159] As is clear from Table 1, a paste-type positive electrode having a current collector filled with a paste containing a binder containing particles having a fluororesin as a main component and having an average particle diameter of 0.2 μm or less, and an active material. In the secondary battery of Example 1 including the above, as compared with the secondary battery of Comparative Example 1 in which the particles having the average particle diameter of more than 0.2 μm as the main component of fluororesin are used as the binder, the positive electrode active material trap It can be seen that the power and charge / discharge cycle life characteristics are excellent.

Example 2 <Preparation of Paste-type Positive Electrode> A mixed powder of 90 parts by weight of nickel hydroxide powder and 10 parts by weight of cobalt oxide powder was added to carboxymethylcellulose. 3 parts by weight and an average particle size of 0.
2.5 parts by weight of a suspension of unburned polytetrafluoroethylene particles (standard specific gravity: 2.2) of 4 μm (specific gravity 1.5, solid content 60% by weight) in terms of solid content and polyacrylic acid 0.5 parts by weight was added, and 45 parts by weight of pure water was added and kneaded to prepare a paste.
Then, after filling this paste into a nickel-plated fiber substrate, further apply the paste to both surfaces thereof,
A paste type positive electrode was produced by drying, rolling with a roller press, and rolling.

<Preparation of Paste Type Negative Electrode> 0.5 part by weight of sodium polyacrylate, 0.125 part by weight of carboxymethyl cellulose (CMC), and 100 parts by weight of the hydrogen storage alloy powder having the same composition as in Example 1 were averaged. Particle size is 0.
Dispersion of 2 μm unburned polytetrafluoroethylene particles (standard specific gravity is 2.2) (specific gravity 1.
5, a solid content of 60 wt%) was mixed with 2.5 parts by weight of solid content and 1.0 part by weight of carbon powder as a conductive material together with 50 parts by weight of water to prepare a paste. This paste was applied to punched metal, dried, and then roller pressed to produce a paste type negative electrode.

Then, a separator similar to that of Example 1 was interposed between the negative electrode and the positive electrode and spirally wound to produce a spiral electrode group. Such an electrode group and the same electrolytic solution as in Example 1 were housed in a bottomed cylindrical container to assemble an AA size cylindrical nickel-hydrogen secondary battery having the structure shown in FIG.

With respect to the obtained negative electrodes of the secondary batteries of Example 2 and Comparative Example 1, the operation of spirally winding was repeated 5 times, and these negative electrodes were weighed and weighed in comparison with those before winding. The degree of dropout was measured by determining how much it had decreased. The results are shown in Table 2 below, assuming that the dropout degree of Comparative Example 1 is 100.

For the secondary battery of Example 2, the number of cycles required until the discharge capacity decreased to 80% of the discharge capacity in the first cycle was obtained in the same manner as described above, and the result is shown in the table below. It is also described in 2. In Table 2, Comparative Example 1
The number of cycles is also shown.

Further, the battery internal pressures of the secondary batteries of Example 2 and Comparative Example 1 were measured. The battery internal pressure was measured by housing the batteries of Example 2 and Comparative Example 1 in the container of the pressure measuring device shown in FIG.

That is, each battery internal pressure measuring device has a battery case composed of an acrylic resin case body 21 and a cap 22. At the center of the case body 21, A
A space 23 having the same inner diameter and height as the metal container of the A-size battery is formed. The secondary battery 24 is housed inside the space 23. The cap 22 is air-tightly fixed on the case body 21 by a bolt 27 and a nut 28 via a packing 25 and an O-ring 26. A pressure detector 29 is attached to the cap 22. A negative electrode lead 30 from the negative electrode and a positive electrode lead 31 from the positive electrode are led out between the packing 25 and the O-ring 26.

The maximum battery internal pressure when the secondary batteries of Example 2 and Comparative Example 1 were charged at 480% at a current of 0.5 CmA was measured by the above battery internal pressure measuring device, and the results are also shown in Table 2 below. To do.

Table 2 Loss Degree Number of Cycles Maximum Battery Internal Pressure Example 2 80 290 4.2 kg / cm ² Comparative Example 1 100 240 5.6 kg / cm ^{2 As is} apparent from Table 2, the average particle size of the binder is 0.
Compared to Comparative Example 1, the secondary battery of Example 2 provided with the paste-type negative electrode using particles containing particles of a fluororesin of 2 μm or less as the main component had a negative electrode active material trapping power, charge / discharge cycle life characteristics and It can be seen that the internal pressure characteristics during overcharge are excellent.

Example 3 A separator similar to that of Example 1 was interposed between a positive electrode similar to Example 1 and a negative electrode similar to Example 2, and spirally wound to form an electrode group. Such an electrode group and the same electrolytic solution as in Example 1 were housed in a bottomed cylindrical container to assemble an AA size cylindrical nickel-hydrogen secondary battery having the structure shown in FIG.

With respect to the obtained secondary battery of Example 3, the maximum internal battery pressure during overcharge was measured in the same manner as described above, and was 3.6 kg / cm ² , which was lower than that of Comparative Example 1. Further, when the number of cycles required until the discharge capacity decreased to 80% of the discharge capacity in the first cycle was obtained in the same manner as described above, it was higher than 310 and Comparative Example 1.

Example 4 <Preparation of Paste Type Negative Electrode> A commercially available lanthanum-enriched misch metal Lm and Ni, Co, Mn, and Al were used in a high-frequency furnace to produce LmNi _4.0 Co _0.4 Mn _0.3 Al.
_A hydrogen storage alloy having a composition of _0.3 was prepared. The hydrogen storage alloy was mechanically pulverized and passed through a 200-mesh sieve. 0.5 parts by weight of sodium polyacrylate, 0.125 parts by weight of carboxymethyl cellulose (CMC), and 100 μ parts by weight of the obtained alloy powder, unfired polytetrafluoroethylene particles having an average particle size of 0.2 μm ( 2.5 parts by weight of a dispersion having a standard specific gravity of 2.2) (specific gravity 1.5, solid content 60 wt%) in terms of solid content and 1.0 part by weight of carbon powder as a conductive material are mixed with 50 parts by weight of water. To prepare a paste.

On the other hand, a punched metal having circular holes was prepared as a current collector. This punched metal has a non-perforated region formed at the end portion orthogonal to the longitudinal direction. The punched metal has a thickness of 80 μm and an aperture ratio of 50%.

The paste having the structure shown in FIG. 5 is formed by applying the paste to the current collector and drying it, and then roller pressing so that the circular holes extend in the longitudinal direction of the punched metal and are deformed into an oval shape. A formula negative electrode was produced.

As shown in FIG. 5, the obtained negative electrode 40 was
It has a structure in which the above-mentioned paste 43 is filled in a punched metal 42 having a non-perforated region 41 formed at an end portion orthogonal to the longitudinal direction. Hole 44 opened in the punched metal 42
Is an ellipse and has a major axis r in the longitudinal direction of the punched metal 42. Further, the hole 44 has a ratio of the major axis r to the minor axis of 1.10.

<Preparation of Paste Positive Electrode> A mixed powder of 90 parts by weight of nickel hydroxide powder and 10 parts by weight of cobalt oxide powder was added to 0.3 parts by weight of carboxymethyl cellulose as a binder for the nickel hydroxide powder. 0.5 parts by weight of a suspension of uncalcined polytetrafluoroethylene particles having an average particle size of 0.4 μm (specific gravity 1.5, solid content 60% by weight) and polyacrylic acid 0 A paste was prepared by adding 3 parts by weight, and adding 45 parts by weight of pure water thereto and kneading. Subsequently, after this paste was filled in a nickel-plated fiber substrate, the paste was further applied to both surfaces thereof, dried, and rolled by roller pressing to produce a paste-type positive electrode.

Then, a separator made of a non-woven fabric made of polyolefin fiber which has been subjected to a hydrophilization treatment is interposed between the negative electrode and the positive electrode and wound in a spiral shape to form the spiral structure shown in FIG. A shaped electrode group was prepared. In the electrode group, the winding start end of the negative electrode faces the side surface of the positive electrode with the separator interposed therebetween. The end of the negative electrode having the non-perforated region of the punched metal is located at the winding start end of the negative electrode. Further, a negative electrode is arranged on the outer circumference of the electrode group, and a winding terminal end of the negative electrode faces a side surface of the negative electrode. The winding start end and winding end of the positive electrode face the side surface of the negative electrode with a separator interposed therebetween.

Such an electrode group and 7N KOH and 1
An electrolytic solution consisting of N LiOH was housed in a bottomed cylindrical container to assemble an AA size cylindrical nickel-hydrogen secondary battery having the structure shown in FIG.

Example 5 A cylindrical nickel-hydrogen secondary battery was assembled in the same manner as in Example 4 except that the ratio of the major axis to the minor axis of the oblong hole of the punched metal of the negative electrode was changed to 1.01. It was

Example 6 A cylindrical nickel-hydrogen secondary battery was assembled in the same manner as in Example 4 except that the ratio of the major axis to the minor axis of the oblong hole of the punched metal of the negative electrode was changed to 1.50. It was

Comparative Example 2 A cylindrical nickel-hydrogen secondary battery was assembled in the same manner as in Example 4 except that the average particle size of the polytetrafluoroethylene particles contained in the negative electrode paste was changed to 0.4 μm.

Comparative Example 3 Except that the arrangement condition of the oval holes of the punched metal of the negative electrode was changed so that the oval holes had a major axis in the direction orthogonal to the longitudinal direction of the punched metal. A cylindrical nickel-hydrogen secondary battery was assembled in the same manner as in Example 4.

Comparative Example 4 A cylindrical nickel-hydrogen secondary battery was assembled in the same manner as in Example 4, except that the non-hole region was not provided in the punched metal of the negative electrode.

Comparative Example 5 A cylindrical nickel hydrogen secondary battery was assembled in the same manner as in Example 4 except that 2.5 parts by weight of a styrene-butadiene copolymer was used as a binder for the negative electrode.

With respect to the obtained negative electrodes of the secondary batteries of Examples 4 to 6 and Comparative Examples 2 to 5, the spiral winding operation was repeated 5 times, and these negative electrodes were weighed and before winding. The degree of dropout was measured by determining how much the weight was reduced in comparison. The results are shown in Table 3 below, assuming that the dropout degree of Example 1 is 100.

Further, with respect to 200 secondary batteries of Examples 4 to 6 and Comparative Examples 2 to 5, the number of batteries having an internal short circuit during assembly was examined, and the results are also shown in Table 3 below.

[0186] In addition, the battery internal pressure was measured for the secondary batteries of Examples 4 to 6 and Comparative Examples 2, 3, and 5. That is, Examples 4 to 6
The batteries of Comparative Examples 2, 3 and 5 were housed in the container of the pressure measuring device shown in FIG.
The maximum battery internal pressure when 80% charged was measured, and the results are shown in Table 4 below.

The secondary batteries of Examples 4 to 6 and Comparative Examples 2, 3 and 5 were charged to 150% at 1 CmA and then charged to 1C.
The charging / discharging cycle of discharging until the battery voltage reaches 1.0 V at mA is repeated, and the discharge capacity is calculated from the time until the battery voltage reaches 1.0 V at 1 CmA at each cycle. The number of cycles required to reduce the discharge capacity to 80% was determined, and the results are also shown in Table 4 below.

Table 4 Maximum Battery Internal Pressure Number of Cycles Example 4 5.1 kg / cm ² 530 Example 5 5.3 kg / cm ² 515 Example 6 5.5 kg / cm ² 520 Comparative Example 2 10.2 kg / cm ² 270 Comparative Example 3 11.0 kg / cm ² 230 Comparative Example 5 15.4 kg / cm ² 220 As is clear from Tables 3 and 4, the secondary batteries of Examples 4 to 6, that is, the average particle size is 0.2 μm or less. Of a negative electrode formed by filling a current collector with a paste containing particles having a fluororesin as a main component, wherein the current collector has an oval shape and has a non-hole region at the winding start end. In the secondary battery having the oval hole having a major axis in the winding direction of the negative electrode, the degree of dropout is low, an internal short circuit at the time of assembly can be avoided, and The rise in internal pressure can be suppressed, Cycle life is seen that for a long time.

On the other hand, although the current collector was the same as in Example 4, the secondary battery of Comparative Example 2 provided with the negative electrode in which the average particle diameter of the polytetrafluoroethylene particles contained in the paste was 0.4 μm It can be seen that, as compared with Examples 4 to 6, the internal pressure during overcharging is higher and the charge / discharge cycle life is shorter.
On the other hand, the same negative electrode as in Example 4 was adopted except that the arrangement of the elliptical holes of the current collector was set so that the elliptical holes had a major axis in a direction orthogonal to the longitudinal direction of the punched metal. It can be seen that the provided secondary battery of Comparative Example 3 has a larger amount of dropout, a higher internal pressure during overcharge, and a shorter charge / discharge cycle life than those of Examples 4 to 6. The secondary battery of Comparative Example 4 provided with the same negative electrode as that of Example 4 except that the non-porous region was not formed had an internal short circuit during assembly. In addition, the paste of the comparative example 5 including a paste containing a styrene-butadiene copolymer as a binder and a negative electrode made of punched metal filled with the paste and having a non-porous region at a winding start end is formed. It can be seen that the secondary battery has a higher degree of dropout, a higher internal pressure during overcharge, and a shorter cycle life as compared with Examples 4 to 6. The reason why the internal pressure characteristics during overcharge are remarkably inferior is that the water repellency of the negative electrode is insufficient because a styrene-butadiene copolymer is used as a binder. Comparative Example 5
When a suspension of polytetrafluoroethylene was applied to the surface of the negative electrode of, the internal pressure during overcharge was still high, and in order to improve the oxygen gas absorption performance of the negative electrode, it is necessary to impart water repellency not only to the surface but also to the inside. Can be said to be important.

Therefore, in order to prevent the active material from falling off during winding, suppress the internal pressure during overcharging, and extend the life at the same time,
It can be seen that the shape and arrangement of the holes in the punched metal and the selection of the binder are important.

Example 7 <Preparation of Paste Type Positive Electrode> A mixed powder of 90 parts by weight of nickel hydroxide powder and 10 parts by weight of cobalt oxide powder was mixed with carboxymethyl cellulose (CMC) as a binder for the nickel hydroxide powder. ), 0.3 parts by weight of polyacrylic acid and nitrile rubber (NB
3.0 parts by weight of the latex R) is added in terms of solid content,
A paste was prepared by adding 45 parts by weight of pure water to these and kneading. This paste is applied to a punched metal (having a thickness of 80 μm and an opening ratio of 50%) made of nickel with a hole having a circular shape and having non-hole regions formed at both ends orthogonal to the longitudinal direction, and after drying, A paste-type positive electrode was produced by roller pressing so that the holes would extend in the longitudinal direction of the punched metal and deform into an oval shape.

In the obtained positive electrode, the oblong hole of the punched metal has a major axis in the longitudinal direction of the punched metal, and the ratio of the major axis to the minor axis of the ellipse is 1.0.
It was 5.

The spiral electrode having the structure shown in FIG. 2 described above is obtained by interposing the separator similar to that of Example 4 between the obtained positive electrode and the negative electrode similar to that of Example 4 and spirally winding the same. Groups were created. In the electrode group, the winding start end of the negative electrode faces the side surface of the positive electrode with the separator interposed therebetween. The end of the negative electrode having the non-perforated region of the punched metal is located at the winding start end of the negative electrode. The winding start end and the winding end end of the positive electrode face the side surface of the negative electrode with a separator interposed therebetween. Both ends of the positive electrode having the non-perforated region of the punched metal are located at a winding start end and a winding end end of the positive electrode. A negative electrode is arranged on the outer circumference of the electrode group, and a winding end portion of the negative electrode faces a side surface of the negative electrode.

The above electrode group and the same electrolytic solution as in Example 4 were housed in a bottomed cylindrical container to assemble an AA size cylindrical nickel-hydrogen secondary battery having the structure shown in FIG.

Example 8 A cylindrical nickel-hydrogen secondary battery similar to that of Example 7 was assembled except that the positive electrode described below was used.

<Preparation of Paste Type Positive Electrode> A mixed powder of 90 parts by weight of nickel hydroxide powder and 10 parts by weight of cobalt oxide powder was added to 0.3 parts by weight of carboxymethyl cellulose as a binder for the nickel hydroxide powder. 0.5 parts by weight of a dispersion (specific gravity 1.5, solid content 60 wt%) of unburned polytetrafluoroethylene particles having an average particle diameter of 0.2 μm (standard specific gravity 2.2) in terms of solid content Then, 0.3 part by weight of polyacrylic acid was added, and 45 parts by weight of pure water was added thereto and kneaded to prepare a paste. This paste was punched metal (having a thickness of 80 μm, which has a circular hole shape, and has non-hole regions formed at both ends orthogonal to the longitudinal direction).
After coating and drying at an aperture ratio of 50%), a paste-type positive electrode was produced by roller pressing so that the holes would extend in the longitudinal direction of the punched metal and deform into an oval shape.

In the obtained positive electrode, the oblong hole of the punched metal has a major axis in the longitudinal direction of the punched metal, and the ratio of the major axis to the minor axis of the ellipse is 1.0.
It was 5.

Example 9 Except that the arrangement of the oval holes in the positive electrode punched metal was changed so that the oval holes had a major axis in a direction orthogonal to the longitudinal direction of the punched metal. A cylindrical nickel-hydrogen secondary battery was assembled in the same manner as in Example 7.

With respect to the obtained positive electrodes of the secondary batteries of Examples 7 to 9, the same drop-off test as described above was carried out, and Example 7
When the drop-off degree was 100, Example 8 was 90, and Example 9 was 120.

When the number of batteries in which the internal short circuit occurred during assembly of 200 secondary batteries of Examples 7 to 9 was examined, no internal short circuit occurred during assembly. In addition, when 200 cylindrical nickel-hydrogen secondary batteries were assembled in the same manner as in Example 7 except that the punched metal of the positive electrode was not provided with a non-hole region, there were 5 batteries with internal short circuit. It was

Further, the charge / discharge cycle life of the secondary batteries of Examples 7 to 9 was measured in the same manner as described above. As a result, the secondary battery of Example 7 was 300, and the secondary battery of Example 8 was At 400, the secondary battery of Example 9 was 240.

Example 10 A cylindrical nickel-hydrogen secondary battery was assembled in the same manner as in Example 4 except that the negative electrode described below was used.

<Preparation of Paste Type Negative Electrode> 0.5 part by weight of sodium polyacrylate and carboxymethyl cellulose (C
MC) 0.125 parts by weight, dispersion of unburned polytetrafluoroethylene particles (standard specific gravity is 2.2) having an average particle size of 0.2 μm (specific gravity 1.5, solid content 6)
0 wt%) was mixed with 2.5 parts by weight in terms of solid content and 1.0 part by weight of carbon powder as a conductive material together with 50 parts by weight of water to prepare a paste. This paste is a punched metal made of nickel with a non-perforated region formed at an end portion orthogonal to the longitudinal direction as a current collector (Vickers hardness is 75 Hv, thickness is 80 μm, and aperture ratio is 50.
%) And dried, and then roller pressed to prepare a paste type negative electrode.

Comparative Example 6 A cylindrical nickel-hydrogen secondary battery was assembled in the same manner as in Example 10 except that the average particle size of the polytetrafluoroethylene particles contained in the negative electrode paste was changed to 0.4 μm.

Comparative Example 7 A cylindrical nickel-hydrogen secondary battery was assembled in the same manner as in Example 10 except that the Vickers hardness of the punched metal of the negative electrode was changed to 30 Hv.

Comparative Example 8 A cylindrical nickel-hydrogen secondary battery was assembled in the same manner as in Example 10 except that the Vickers hardness of the punched metal of the negative electrode was changed to 120 Hv.

Comparative Example 9 A cylindrical nickel-hydrogen secondary battery was assembled in the same manner as in Example 10 except that the non-hole region was not provided in the punched metal of the negative electrode.

With respect to the obtained negative electrodes of the secondary batteries of Example 10 and Comparative Examples 6 to 9, the spiral winding operation was repeated 5 times, and these negative electrodes were weighed and compared with those before winding. The degree of shedding was measured by determining how much the weight had decreased. The results are shown in Table 5 below, assuming that the degree of drop in Example 10 is 100.

Further, with respect to 200 secondary batteries of Example 10 and Comparative Examples 6 to 9, the number of batteries having an internal short circuit during assembly was checked, and the results are also shown in Table 5 below.

[0210] The maximum battery internal pressure during overcharge was measured for the secondary batteries of Example 10 and Comparative Examples 6, 7, and 8 by the same method as described above, and the results are shown in Table 6 below.

The same cycle test as described above was performed on the secondary batteries of Example 10 and Comparative Examples 6 to 8, and the results are also shown in Table 6 below.

Table 6 Maximum Battery Internal Pressure Number of Cycles Example 10 5.4 kg / cm ² 520 Comparative Example 6 10.7 kg / cm ² 340 Comparative Example 7 11.2 kg / cm ² 310 Comparative Example 8 11.3 kg / cm ² 290 As is apparent from Tables 5 and 6, the secondary battery of Example 10, that is, the negative electrode formed by filling the current collector with a paste containing polytetrafluoroethylene particles having an average particle size of 0.2 μm or less. The current collector has a Vickers hardness of 40 to 40 in which a non-hole region is formed at the winding start end.
It can be seen that the secondary battery made of punched metal of 100 Hv has a low degree of dropout, can avoid an internal short circuit during assembly, can suppress an increase in internal pressure during overcharge, and has a long cycle life.

On the other hand, the secondary battery of Comparative Example 6 having the same current collector as in Example 10 but provided with the negative electrode in which the average particle diameter of the polytetrafluoroethylene particles contained in the paste was 0.4 μm It can be seen that, in comparison with Example 10, the internal pressure during overcharging is higher and the charge / discharge cycle life is shorter.
On the other hand, the secondary batteries of Comparative Examples 7 and 8 provided with the same negative electrode as that of Example 7 except that the Vickers hardness was out of the above range had a higher internal pressure during overcharge than Example 10, and had a charge-discharge cycle. You can see that the life is short. In addition, the secondary battery of Comparative Example 9 including the same negative electrode as that of Example 10 except that the non-porous region was not formed had an internal short circuit during assembly.

Example 11 <Preparation of Paste Type Positive Electrode> A mixed powder of 90 parts by weight of nickel hydroxide powder and 10 parts by weight of cobalt oxide powder was added to carboxymethyl cellulose (CMC) as a binder for the nickel hydroxide powder. ), 0.3 parts by weight of polyacrylic acid and nitrile rubber (NB
3.0 parts by weight of the latex R) is added in terms of solid content,
A paste was prepared by adding 45 parts by weight of pure water to these and kneading. This paste is a punched metal made of nickel with a non-perforated region formed at both ends orthogonal to the longitudinal direction as a current collector (Vickers hardness of 75H
v, thickness 80 μm, aperture ratio 50%), dried and then roller pressed to prepare a paste-type negative electrode.

The spiral electrode having the structure shown in FIG. 2 described above was obtained by interposing the separator similar to that of Example 4 between the obtained positive electrode and the negative electrode similar to that of Example 10 and spirally winding the same. Groups were created. In the electrode group, the winding start end of the negative electrode faces the side surface of the positive electrode with the separator interposed therebetween. The end of the negative electrode having the non-perforated region of the punched metal is located at the winding start end of the negative electrode. The winding start end and the winding end end of the positive electrode face the side surface of the negative electrode with a separator interposed therebetween. Both ends of the positive electrode having the non-perforated region of the punched metal are located at a winding start end and a winding end end of the positive electrode. A negative electrode is arranged on the outer circumference of the electrode group, and a winding end portion of the negative electrode faces a side surface of the negative electrode.

The electrode group and the same electrolytic solution as in Example 4 were housed in a cylindrical container having a bottom to assemble an AA size cylindrical nickel-hydrogen secondary battery having the structure shown in FIG.

Example 12 A cylindrical nickel-hydrogen secondary battery similar to that in Example 11 was assembled except that the positive electrode described below was used.

<Preparation of Paste-type Positive Electrode> A mixed powder of 90 parts by weight of nickel hydroxide powder and 10 parts by weight of cobalt oxide powder was added to 0.3 parts by weight of carboxymethyl cellulose based on the nickel hydroxide powder, and an average particle diameter was measured. Is 0.
Dispersion of 2 μm unburned polytetrafluoroethylene particles (standard specific gravity is 2.2) (specific gravity 1.
5, solid content 60 wt%) was added in an amount of 0.5 part by weight in terms of solid content, and 45 parts by weight of pure water was added and kneaded to prepare a paste. This paste is a punched metal (Vickers hardness of 7 or less) made of nickel with non-perforated regions formed at both ends orthogonal to the longitudinal direction of the current collector.
A paste-type negative electrode was prepared by applying 5 Hv, a thickness of 80 μm, and an aperture ratio of 50%), drying and then roller pressing.

Example 13 The punched metal of the positive electrode had a Vickers hardness of 130H.
A cylindrical nickel-hydrogen secondary battery was assembled in the same manner as in Example 11 except that the value was changed to v.

The positive electrodes of the obtained secondary batteries of Examples 11 to 13 were subjected to the same drop-off test as described above, and the drop-off degree of Example 11 was set to 100.
0, Example 13 was 110.

In addition, the secondary batteries 200 of Examples 11 to 13
Regarding the number of batteries, when the number of batteries in which an internal short circuit occurred during assembly was examined, no internal short circuit occurred during assembly in any of the secondary batteries. In addition, when 200 cylindrical nickel-hydrogen secondary batteries were assembled in the same manner as in Example 11 except that the punched metal of the positive electrode was not provided with a non-perforated region, there were 3 batteries in which an internal short circuit occurred. It was

Further, the charge / discharge cycle life of the secondary batteries of Examples 11 to 13 was measured in the same manner as described above. As a result, the secondary battery of Example 11 was 360, and the secondary battery of Example 12 was In 410, the secondary battery of Example 13 is 2
It was 90.

Example 14 A cylindrical nickel-hydrogen secondary battery similar to that in Example 11 was assembled except that the same negative electrode as in Example 4 and the same positive electrode as in Example 12 were used.

Example 15 A cylindrical nickel metal hydride secondary battery similar to that in Example 11 was assembled except that the same negative electrode as in Example 10 and the same positive electrode as in Example 8 were used.

When 200 secondary batteries of Examples 14 and 15 were checked for the number of batteries having an internal short circuit during assembly, no internal short circuit occurred during assembly.

Further, the charge / discharge cycle life of the secondary batteries of Examples 14 and 15 was determined in the same manner as described above. As a result, the secondary battery of Example 14 had 440 and Example 1
The secondary battery of No. 5 was 460.

In Examples 4 to 15, the non-hole region was not provided at the winding end of the punched metal of the negative electrode, but the effect of avoiding an internal short circuit during assembly and charging / discharging cycle was further improved. It is preferable to provide a non-perforated region at the winding end in order to improve

Example 16 <Preparation of Paste Type Positive Electrode> A mixed powder of 90 parts by weight of nickel hydroxide powder and 10 parts by weight of cobalt oxide powder was mixed with carboxymethyl cellulose (CMC) as a binder for the nickel hydroxide powder. ), 0.3 parts by weight of polyacrylic acid and nitrile rubber (NB
3.0 parts by weight of the latex R) is added in terms of solid content,
A paste was prepared by adding 45 parts by weight of pure water to these and kneading. This paste was applied to punched metal, dried, and then roller pressed to produce a paste type negative electrode.

<Preparation of Paste Type Negative Electrode> 0.5 parts by weight of sodium polyacrylate, 0.125 parts by weight of carboxymethyl cellulose (CMC) and conductivity with respect to 100 parts by weight of hydrogen storage alloy powder having the same composition as in Example 1. As a material, 1.0 part by weight of carbon powder was mixed with 50 parts by weight of water. Add an aqueous solution of polyoxyethylene alkyl phenyl ether, which is a surfactant, to the solid content of 0.01
After adding parts by weight and further kneading, the average particle size is 0.4μ.
A paste was prepared by adding 1.5 parts by weight of m non-calcined polytetrafluoroethylene particles (standard specific gravity is 2.2) and kneading. This paste was applied to punched metal, dried, and then roller pressed to produce a paste type negative electrode.

Then, a separator similar to that of Example 1 was interposed between the negative electrode and the positive electrode and spirally wound to prepare a spiral electrode group. Such an electrode group and an electrolytic solution similar to that of Example 1 are housed in a cylindrical container having a bottom to have the structure shown in FIG. 1 described above, and a cylindrical nickel-hydrogen secondary having an AA size and a nominal capacity of 1200 mAh. I assembled the battery.

Example 17 The blending amount of the aqueous surfactant solution was 0.5 in terms of solid content.
A nickel-hydrogen secondary battery was assembled in the same manner as in Example 16 except that the parts by weight were used.

Example 18 The blending amount of the aqueous surfactant solution was 1.0 in terms of solid content.
A nickel-hydrogen secondary battery was assembled in the same manner as in Example 16 except that the parts by weight were used.

Comparative Example 10 The blending amount of the aqueous solution of the surfactant was 0.0 in terms of solid content.
A nickel-hydrogen secondary battery was assembled in the same manner as in Example 16 except that the amount was 05 parts by weight.

Comparative Example 11 The blending amount of the aqueous surfactant solution was 1.5 in terms of solid content.
A nickel-hydrogen secondary battery was assembled in the same manner as in Example 16 except that the parts by weight were used.

Obtained Examples 16 to 18 and Comparative Example 1
For the negative electrodes of the secondary batteries of 0 and 11, the operation of winding in a spiral shape was repeated 5 times, and then these negative electrodes were weighed to determine how much the weight decreased compared to before winding, and the degree of dropout was determined. Was measured. The results are shown in Table 7 below, where the degree of drop in Example 18 is 100.

Obtained Examples 16 to 18 and Comparative Example 1
For the secondary batteries 0 and 11, the maximum battery internal pressure and the number of cycles required until the discharge capacity dropped to 80% of the discharge capacity at the first cycle were measured in the same manner as described above. The results are also shown in Table 7 below.

Table 7 Loss Degree Number of Cycles Maximum Battery Internal Pressure Example 16 95 290 4.4 kg / cm ² Example 17 99 300 4.1 kg / cm ² Example 18 100 305 3.8 kg / cm ² Comparative Example 10 86 250 4.5 kg / cm ² Comparative Example 11 100 270 7.2 kg / cm ^{2 As is} clear from Table 7, the binder containing the unfired polytetrafluoroethylene particles and the hydrogen storage alloy 100
The secondary batteries of Examples 16 to 18 provided with the paste-type hydrogen storage alloy negative electrodes containing the surfactant in the range of 0.01 to 1.0 parts by weight based on parts by weight, the content of the surfactant. It can be seen that the negative electrode active material trapping power, charge / discharge cycle life characteristics, and internal pressure characteristics during overcharge are superior to the secondary batteries of Comparative Examples 10 and 11 in which the value exceeds the above range.

Example 19 A cylindrical nickel-hydrogen secondary battery similar to that of Example 16 was assembled except that the negative electrode described below was used.

<Preparation of Paste Type Negative Electrode> 0.5 parts by weight of sodium polyacrylate, 0.125 parts by weight of carboxymethyl cellulose (CMC) and conductivity with respect to 100 parts by weight of hydrogen storage alloy powder having the same composition as in Example 1. As a material, 1.0 part by weight of carbon powder was mixed with 50 parts by weight of water. A paste was prepared by adding 1.5 parts by weight of the same polytetrafluoroethylene particles as in Example 16 and 0.1 parts by weight of the same aqueous surfactant solution as in Example 16 in terms of solid content and kneading. . This paste was applied to punched metal, dried, and then roller pressed to produce a paste type negative electrode.

With respect to the obtained secondary battery of Example 19,
When the maximum battery internal pressure during overcharge was measured in the same manner as described above, it was 3.5 kg / cm ² . Further, when the number of cycles required until the discharge capacity was reduced to 80% of the discharge capacity in the first cycle was obtained in the same manner as described above, it was 310.

[0241]

As described above in detail, according to the paste type electrode and the alkaline secondary battery of the present invention, the adhesion between the active material and the current collector can be improved, the capacity can be increased and the life can be extended. It is possible to achieve remarkable effects such as being made more efficient. Further, according to another paste-type electrode according to the present invention, it is possible to avoid an internal short circuit, improve the winding property, and improve the active material holding power of the current collector, and have a high capacity alkaline secondary battery. It is possible to provide a remarkable effect. Further, according to another alkaline secondary battery of the present invention, it is possible to increase the volume of the electrode group housed in the container without causing an inconvenience such as an internal short circuit, and suppress an increase in internal pressure during overcharge. And a remarkable effect such as improvement in capacity and charge / discharge cycle life can be achieved. According to still another alkaline secondary battery and a method for manufacturing an alkaline secondary battery according to the present invention, it is possible to suppress or prevent the active material from falling off during assembly or during charging / discharging cycles, and to prevent internal pressure during overcharge. It is possible to suppress the rise, and it is possible to achieve remarkable effects such as a higher capacity and a longer life.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing an alkaline secondary battery (for example, a cylindrical alkaline secondary battery) according to the present invention.

FIG. 2 is a sectional view showing a central portion of an electrode group incorporated in the alkaline secondary battery of the present invention.

FIG. 3 is a cross-sectional view showing a central portion of an electrode group incorporated in another alkaline secondary battery of the present invention.

FIG. 4 is a sectional view showing a pressure measuring device used in an embodiment of the present invention.

FIG. 5 is a partially cutaway plan view showing a negative electrode in an alkaline secondary battery of Example 4 of the present invention.

[Explanation of symbols]

1 ... Container, 2 ... Positive electrode, 3 ... Separator, 4 ... Negative electrode, 5 ...
Electrode group, 7 ... sealing plate.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location H01M 10/28 H01M 10/28 A

Claims (14)

[Claims] 1. A paste-type electrode having a structure in which a paste containing an active material and a binder is held on a current collector, wherein the binder mainly comprises a fluororesin having an average particle diameter of 0.2 μm or less. A paste-type electrode, comprising: 2. A positive electrode configured to hold a paste containing an active material and a binder on a current collector, a negative electrode configured to hold a paste containing an active material and a binder on a current collector, and an alkaline electrolyte. The alkaline secondary battery, wherein the binder for the positive electrode and / or the negative electrode contains particles having an average particle diameter of 0.2 μm or less as a main component of a fluororesin. 3. A paste-type electrode having a structure in which a paste containing an active material and a binder is held on a current collector, wherein the binder mainly comprises a fluororesin having an average particle size of 0.2 μm or less. The current collector is a punched metal having a non-perforated region on at least one end portion orthogonal to the longitudinal direction, the holes opened in the punched metal are oval, and the punched metal A paste-type electrode characterized by having a major axis in the longitudinal direction of metal. 4. A paste-type electrode having a structure in which a paste containing an active material and a binder is held on a current collector, wherein the binder mainly comprises a fluororesin having an average particle diameter of 0.2 μm or less. The current collector has a Vickers hardness of 40 to 10 in which a non-porous region is formed on at least one end portion orthogonal to the longitudinal direction.
A paste-type electrode characterized by being made of punched metal of 0 Hv. 5. A spirally wound electrode group with a separator interposed between a negative electrode and a positive electrode configured to hold a paste containing an active material and a binder on a current collector; an alkaline electrolyte;
The binder contains particles having an average particle diameter of 0.2 μm or less and a fluororesin as a main component, and the current collector of the negative electrode has at least the positive electrode of the winding start end and the winding end end. Punched metal having a non-perforated region formed at an end portion facing to, the hole opened in the punched metal is oval and has a major axis in a winding direction of the negative electrode. And alkaline secondary battery. 6. A separator is provided between a positive electrode configured to hold a paste containing an active material and a binder on a current collector and a negative electrode configured to hold a paste containing an active material and a binder on a current collector. An electrode group formed by interposing and spirally winding; an alkaline electrolyte; and at least the binder for the negative electrode has an average particle size of 0.2 μm.
The current collector of the positive electrode includes the following particles containing a fluororesin as a main component, and the positive electrode current collector is a punch in which a non-porous region is formed at least at an end facing the negative electrode, of a winding start end and a winding end end. A hole in the punched metal, the hole being opened in the punched metal and having a major axis in the winding direction of the positive electrode, and the current collector of the negative electrode having a winding start end and a winding end end. Of the punched metal, a non-perforated region is formed at least at the end facing the positive electrode, and the hole opened in the punched metal is oval and has a major axis in the winding direction of the negative electrode. An alkaline secondary battery characterized by having. 7. An electrode group spirally wound with a separator interposed between a negative electrode and a positive electrode configured to hold a paste containing an active material and a binder on a current collector; an alkaline electrolyte;
The binder includes particles having an average particle diameter of 0.2 μm or less and a fluororesin as a main component, and the current collector of the negative electrode has at least one of a winding start end and a winding end end. An alkaline secondary battery comprising a punched metal having a Vickers hardness of 40 to 100 Hv in which a non-hole region is formed at an end facing the positive electrode. 8. A separator is provided between a positive electrode configured to hold a paste containing an active material and a binder on a current collector and a negative electrode configured to hold a paste containing an active material and a binder on a current collector. An electrode group formed by interposing and spirally winding; an alkaline electrolyte; and at least the binder for the negative electrode has an average particle size of 0.2 μm.
The current collector of the positive electrode includes the following particles containing a fluororesin as a main component, and a non-porous region is formed in at least an end of the winding start end and the winding end that faces the negative electrode. The negative electrode current collector was made of punched metal having a Vickers hardness of 40 to 100 Hv, and a non-porous region was formed in at least an end portion of the winding start end portion and the winding end end portion facing the positive electrode. An alkaline secondary battery comprising a punched metal having a Vickers hardness of 40 to 100 Hv. 9. A separator is provided between a positive electrode configured to hold a paste containing an active material and a binder on a current collector and a negative electrode configured to hold a paste containing an active material and a binder on a current collector. An electrode group formed by interposing and spirally winding; an alkaline electrolyte; and at least the binder for the negative electrode has an average particle size of 0.2 μm.
The current collector of the positive electrode includes the following particles containing a fluororesin as a main component, and a non-porous region is formed in at least an end of the winding start end and the winding end that faces the negative electrode. The current collector of the negative electrode is made of punched metal having a Vickers hardness of 40 to 100 Hv, and has a hole-free region formed at least at a winding start end and a winding end end facing the positive electrode. An alkaline secondary battery, which is a demetal, wherein the hole opened in the punched metal is oval and has a major axis in a winding direction of the negative electrode. 10. A separator is provided between a positive electrode configured to hold a paste containing an active material and a binder on a current collector and a negative electrode configured to hold a paste containing an active material and a binder on a current collector. An electrode group formed by interposing and spirally winding; an alkaline electrolyte; at least the binder for the negative electrode has an average particle size of 0.2 μm.
The current collector of the positive electrode includes the following particles containing a fluororesin as a main component, and the positive electrode current collector is a punch in which a non-porous region is formed at least at an end facing the negative electrode, of a winding start end and a winding end. A hole in the punched metal, the hole having an oval shape and a long diameter in the winding direction of the positive electrode, and the negative electrode current collector has a winding start end and a winding end end. An alkaline secondary battery comprising a punched metal having a Vickers hardness of 40 to 100 Hv in which a non-porous region is formed at least in an end portion facing the positive electrode. 11. In the electrode group, the winding start end portion of the negative electrode is opposed to the side surface of the positive electrode with the separator interposed therebetween.
The alkaline secondary battery according to the item. 12. A paste-type negative electrode containing a hydrogen storage alloy, polytetrafluoroethylene, and 0.01 to 1.0 part by weight of a surfactant with respect to 100 parts by weight of the hydrogen storage alloy, a positive electrode, and an alkaline electrolyte. An alkaline secondary battery comprising: 13. A method of manufacturing an alkaline secondary battery comprising a positive electrode, a negative electrode, and an alkaline electrolyte, wherein the negative electrode contains a hydrogen storage alloy, a conductive agent and a hydrophilic binder in the presence of water. After kneading in, after adding a surfactant aqueous solution and kneading, a step of preparing a paste by further adding and kneading polytetrafluoroethylene particles that have not been fired, filling the current collector with the paste or A method for manufacturing an alkaline secondary battery, which is produced by a method including a step of applying. 14. A method for manufacturing an alkaline secondary battery comprising a positive electrode, a negative electrode and an alkaline electrolyte, wherein the negative electrode comprises a hydrogen storage alloy, a conductive agent and a hydrophilic binder in the presence of water. After kneading in step 1, a step of preparing a paste by adding an aqueous surfactant solution and unfired polytetrafluoroethylene particles and kneading, and a step of filling or applying the paste to a current collector A method for manufacturing an alkaline secondary battery, characterized by being manufactured by the method described above.