JP3349646B2 - Manufacturing method of alkaline secondary battery - Google Patents

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 producing an alkaline secondary battery.

[0002]

2. Description of the Related Art A nickel-metal hydride secondary battery, which is an example of an alkaline secondary battery, has an electrode group produced by interposing a separator between a paste-type positive electrode and a paste-type negative electrode, together with an alkaline electrolyte in a container. Has a stored structure. The secondary battery has excellent voltage compatibility with a nickel cadmium secondary battery including a negative electrode including a cadmium compound instead of the hydrogen storage alloy, and has a higher capacity than the nickel cadmium secondary battery. Has characteristics.

[0003] The paste-type positive electrode is prepared by preparing a paste containing nickel hydroxide particles, a binder and water, and filling or applying the paste to a nickel-plated metal porous body as a current collector. . On the other hand, the paste type negative electrode is produced by preparing a paste containing a hydrogen storage alloy powder, a binder and water, and filling or applying the paste to a punched metal as a current collector.

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

[0005] 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 power of the binder for retaining the nickel hydroxide particles on the current collector is reduced. And the nickel hydroxide particles fall off from the positive electrode with the progress of the electrode group manufacturing process and the charge / discharge cycle. Also, there is a problem that the dropped nickel hydroxide particles come into contact with the negative electrode to cause an internal short circuit.

On the other hand, in the paste type negative electrode, if 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 reduced and the internal pressure of the battery is increased.

That is, since the nickel-metal hydride 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 passes through the separator and is consumed on the surface of the hydrogen storage alloy of the negative electrode by the reaction represented by the following formulas (2) and (3). Thus, the internal pressure of the battery is suppressed from increasing, thereby enabling the hermetic sealing.

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

Japanese Patent Application 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. A hydrogen-absorbing alloy electrode comprising a mixture mainly comprising hydrogen-absorbing alloy powder, and a punching metal serving as a conductive support for supporting the mixture. The punching metal has a hole diameter of 1.0 mm or more and 2.5 mm or less, and a vertex angle of a triangle formed by connecting the centers of three adjacent holes is 46 mm.
５８58 °, the base angle of which is 67-61 ° satisfies the condition of an isosceles triangle. The solid portion is formed at the end of the piercing portion corresponding to the axial end of the cylindrical roll. And wherein the base of the triangle is in a plane perpendicular to the axis of the cylindrical roll. Further, in the examples of the above publication, the polymerization ratio of styrene and butadiene was 1 as the binder for the negative electrode.
It is described that a styrene-butadiene copolymer having a ratio of 00 to 30 to 100 is used.

[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 the fluororesin is uniformly dispersed in the paste and having improved adhesion between the active material and the current collector. It is to be.

SUMMARY OF THE INVENTION An object of the present invention is to prevent a short circuit during assembly in a battery provided with a spiral electrode group, and to improve the adhesion between a paste and a current collector and the rollability of a paste type electrode. It is intended to provide.

It is another object of the present invention to improve the winding property of the electrode, to prevent the active material from falling off when producing the spiral electrode group, and to prevent the internal short circuit at the time of assembling the battery. An object of the present invention is 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, the adhesion between the hydrogen storage alloy and the current collector and the oxygen gas absorption performance at the time of overcharge are improved. It is an object of the present invention to provide an alkaline secondary battery which suppresses a rise in internal pressure during overcharge, has a high capacity, and has a long service life, and a method for manufacturing the alkaline secondary battery.

[0017]

A paste-type electrode according to the present invention is a paste-type electrode configured to hold a paste containing an active material and a binder on a current collector, wherein the binder has an average particle size. It is characterized by including particles mainly composed of a fluororesin having a diameter of 0.2 μm or less. In addition, the present invention
The method for producing an alkaline secondary battery according to
Of an alkaline secondary battery provided with an alkaline electrolyte
Method, a hydrogen storage alloy, a conductive agent and a hydrophilic binder
After kneading in the presence of water,
Kneaded, and further, the average particle size is 0.2 μm or less.
Add and knead calcined polytetrafluoroethylene particles
Preparing a paste by applying
Filling or coating the current collector on the current collector
The negative electrode is manufactured by
You. Another alkaline secondary battery manufacturing method according to the present invention,
An alkaline battery comprising a positive electrode, a negative electrode, and an alkaline electrolyte
A method for manufacturing a secondary battery, comprising: a hydrogen storage alloy, a conductive agent, and
After kneading the hydrophilic binder in the presence of water,
Aqueous solution and an unfired powder having an average particle size of 0.2 μm or less.
Adding and mixing kneaded tetrafluoroethylene particles
Preparing a paste by the method and collecting the paste
Filling or applying to the body
The method is characterized in that the negative electrode is manufactured.

In the alkaline secondary battery according to the present invention, a positive electrode having a structure in which a paste containing an active material and a binder is held on a current collector, and a paste containing an active material and a binder are held on a current collector. A negative electrode having the above structure and an alkaline electrolyte are provided, and the binder for the positive electrode and / or the negative electrode has an average particle diameter of 0.1 to 0.3.
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 configured to hold a paste containing an active material and a binder on a current collector, wherein the binder has an average particle size of 0.2.
μm or less containing a particle containing a fluororesin as a main component, the current collector is a punched metal having a non-porous region at at least one end orthogonal to the longitudinal direction, and is opened in the punched metal. The hole is oval 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 configured to hold a paste containing an active material and a binder on a current collector, wherein the binder has an average particle size of 0.2.
μm or less containing particles mainly composed of a fluororesin, wherein the current collector has a Vickers hardness of 40 to 100H in which a non-porous region is formed on at least one end perpendicular to the longitudinal direction.
v punched metal.

[0021] The alkaline secondary battery according to the present invention has an electrode wound spirally 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 binder; an alkaline electrolyte; wherein the binder includes particles mainly composed of a fluororesin having an average particle diameter of 0.2 μm or less, and the current collector of the negative electrode has a winding start end and a winding end end. A punched metal having a non-porous region formed at least at an end thereof facing the positive electrode, wherein the hole opened in the punched metal has an oval shape, and extends in the winding direction of the negative electrode. It has a major axis.

In the alkaline secondary battery according to the present invention, a positive electrode configured to hold a paste containing an active material and a binder on a current collector, and a paste containing an active material and a binder are held on a current collector. An electrode group formed by spirally winding a separator with a separator interposed between the negative electrodes having the above structure; an alkaline electrolyte; and at least the binder of the negative electrode has an average particle size of 0.2 μm or less. Wherein the current collector of the positive electrode has a non-porous region formed at least at the end facing the negative electrode of the winding start end and the winding end end. Metal, the hole opened in the punched metal is oblong, and has a long diameter 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. At least the non-porous area at the end facing the positive electrode 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 has an electrode wound spirally 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 binder; an alkaline electrolyte; wherein the binder comprises particles mainly composed of a fluororesin having an average particle diameter of 0.2 μm or less, and the current collector of the negative electrode has a winding start end and a winding end. A non-porous region is formed at least at an end of the end facing the positive electrode, and has a Vickers hardness of 40 to 10.
It is characterized by being made of punched metal of 0 Hv.

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

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

In the alkaline secondary battery according to the present invention, a positive electrode configured to hold a paste containing an active material and a binder on a current collector, and a paste containing an active material and a binder are held on a current collector. An electrode group formed by spirally winding a separator with a separator interposed between the negative electrodes having the above structure; an alkaline electrolyte; and at least the binder of the negative electrode has an average particle size of 0.2 μm or less. Wherein the current collector of the positive electrode has a non-porous region formed at least at the end facing the negative electrode of the winding start end and the winding end end. Metal, the hole opened in the punched metal is oval, and has a long diameter 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. At least the non-porous area at the end facing the positive electrode Vickers hardness is formed 40
-100 Hv of punched metal.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION An alkaline secondary battery according to the present invention comprises a positive electrode having a structure in which a paste containing an active material and a binder is held on a current collector, and a current collector containing a paste containing the active material and a binder. A negative electrode configured to be held by the body, and an alkaline electrolyte, wherein the binder of the positive electrode and / or the negative electrode includes particles mainly composed of a fluororesin having an average particle diameter 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 produced by stacking the positive electrode 2, the separator 3, and the negative electrode 4 and winding them in a spiral shape is accommodated in the 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, the separator 3
And 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 carried on a current collector. The binder has an average particle size of 0.2 μm
The following particles containing a fluororesin as a main component are included.

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

Above all, the hydrogen storage alloy is preferable because the capacity of the secondary battery can be improved as compared with the case where the cadmium compound is used. 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 (where R is at least one element selected from rare earth elements including La and Y or a 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 each represent an atomic ratio of x ≧ 0.4 and 0 ≦ y ≦ 2.0).

Examples of the particles mainly composed of the fluororesin include particles mainly composed of polytetrafluoroethylene and particles mainly composed of a tetrafluoroethylene-hexafluoropropylene copolymer. Of the particles containing polytetrafluoroethylene as a main component, unfired particles are preferable because shearing (shear) causes fibrillation and can improve the strength of the negative electrode.

The average particle diameter of the particles mainly composed of the fluororesin is measured by the following method. That is, using an electron microscope, the maximum diameter of the primary particles in the visual field 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 diameter is defined as the average particle diameter 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 inferior, so that the adhesion between the active material and the current collector and the gas absorption performance of the negative electrode may be reduced. The smaller the particle size is, the better the dispersibility is improved.

The above-mentioned particles mainly composed of unfired polytetrafluoroethylene having an average particle diameter 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 a specific gravity of a tetrafluoroethylene molded product obtained under molding and firing conditions specified in JIS standard ASTM D1457. As the standard specific gravity decreases, the polytetrafluoroethylene particles tend to have a low molecular weight and a low degree of fiberization. Polytetrafluoroethylene having a standard specific gravity of 2.1 or less significantly reduces the degree of fiberization, and thus may reduce the adhesion between the paste and the current collector. On the other hand, it is difficult to produce particles having an average particle size of 0.2 μm or less from the polytetrafluoroethylene having a standard specific gravity of more than 2.3 by the current technology. If polytetrafluoroethylene having a standard specific gravity exceeding 2.3 is used, the production cost may be increased. More preferably, the particles have an average particle size in the range of 0.05 to 0.15 μm and a standard specific gravity in the range of 2.15 to 2.25.

The binder may be formed only of particles mainly composed of a fluororesin having an average particle diameter of 0.2 μm or less, or may contain another polymer.

Examples of the polymer used in combination with the fluororesin particles include polyethylene, polypropylene, rubber-based polymers (eg, latex of polypropylene styrene butadiene rubber (SBR), latex of acrylonitrile butadiene rubber (NBR), and ethylene propylene diene monomer (EPDM). ), 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 acrylate and vinyl alcohol, copolymer of maleic acid and vinyl alcohol, etc. Hydrophilic polymer; and the like. The polyethylene and the polypropylene can be used in the form of a dispersion.

The amount of the particles containing a fluororesin as a main component having an average particle diameter in the above range is determined according to the hydrogen storage alloy 100
It is preferable that the amount be in the range of 0.5 to 5.0 parts by weight based on parts by weight. When the addition amount is less than 0.5 parts by weight,
There is a possibility that it may be difficult to enhance the adhesion between the hydrogen storage alloy and the current collector and the gas absorption performance of the negative electrode. On the other hand, if the addition amount exceeds 5.0 parts by weight, the amount of the hydrogen storage alloy contained in the paste is reduced, so that the capacity of the negative electrode may be reduced. A more preferable addition amount is 100%.
It is in the range of 1.0 to 3.0 parts by weight based on parts by weight.

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

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

For the negative electrode, for example, a paste is prepared by kneading an active material (host matrix of an active material), a conductive material, a binder and water, and the paste is filled or coated on a current collector, and dried. After that, it can be produced by molding. The particles containing the fluororesin as a main component can be added to the paste in the form of a 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 similar to the above-described first negative electrode except that a binder containing no particles mainly composed of fluororesin having an average particle diameter of 0.2 μm or less is used as a binder. 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 following particles containing a fluororesin as a main component are included.

The active material includes 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
It is preferable that the tap density is 1.8 g / cm ³ or more.

The nickel hydroxide particles have a specific surface area of 8
Preferably it is ２５25 m ² / g.

Examples of the particles mainly containing a fluororesin as the binder include those similar to those described in the first negative electrode.

The average particle diameter of the particles mainly composed of the fluororesin is measured by the same method as described for the first negative electrode.

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

The above-mentioned particles mainly composed of unfired polytetrafluoroethylene having an average particle diameter of 0.2 μm or less have a standard specific gravity (SSG) for the same reason as described for the 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 a standard specific gravity of 2.15 to
Particles in the 2.25 range.

The binder may be formed only of particles mainly composed of a fluororesin having an average particle diameter of 0.2 μm or less, or may contain another polymer.

Examples of the polymer used in combination with the fluororesin particles include the same polymers as those described in the first negative electrode.

The amount of the particles containing a fluororesin as a main component having an average particle diameter in the above-mentioned range depends on the nickel hydroxide 10
It is preferable to set the amount to 0.5 to 5.0 parts by weight with respect to 0 parts by weight. If the amount is less than 0.5 part by weight, it may be difficult to enhance the adhesion between 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 decreases, and the capacity of the positive electrode may decrease. A more preferable addition amount is 1 to 100 parts by weight of nickel hydroxide.
It is in the range of 0 to 4.0 parts by weight.

It is preferable that 0.2 to 5.0 parts by weight (more preferably 0.3 to 2.0 parts by weight) of the combined polymer is mixed with 100 parts by weight of the nickel hydroxide.

Examples of the current collector include a sponge-like porous metal body and a metal fiber mat.

For the positive electrode, for example, a paste containing nickel hydroxide powder, a conductive agent, a binder and water is prepared,
The current collector is filled or coated with the paste, dried, pressed, and then cut 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 the conductive agent to be added is preferably in the range of 5 to 10 parts by weight based on 100 parts by weight of the nickel hydroxide.

<Second Positive Electrode> This positive electrode is similar to the first positive electrode described above except that the binder does not contain a particle mainly composed of a fluororesin having an average particle diameter of 0.2 μm or less as a binder. It has a similar configuration.

(3) Separator 3 Examples of the separator 3 include a nonwoven fabric made of a polyolefin fiber, a nonwoven fabric made of a nylon fiber, and a nonwoven fabric made of a mixture of a polyolefin fiber and a nylon fiber. In particular, a nonwoven fabric made of polyolefin fiber whose surface has been subjected to a hydrophilic treatment 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 has a configuration in which one of the above two types of positive electrodes and one of the above two types of negative electrodes are provided. . However, the secondary battery does not have a configuration including the second positive electrode and the second negative electrode described above.

In FIG. 1 described above, the separator 3 is interposed between the negative electrode 4 and the positive electrode 2 and spirally wound and accommodated in the cylindrical container 1 having a bottom. The separator may be interposed therebetween to form a laminate, and the laminate may be stored in a bottomed rectangular cylindrical container.

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

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

The electrode group may have a structure in which the winding start end of the negative electrode is opposed to the winding start end or side surface of the positive electrode via the separator, or the winding end of the negative electrode may be provided with the positive electrode via the separator. The winding end portion or side surface of the negative electrode, or the winding start end portion of the negative electrode faces the winding start end portion or side surface of the positive electrode via the separator, and the winding end portion of the negative electrode is the separator. It is preferable to have a structure facing the winding end portion or side surface of the positive electrode through the intermediary.

In particular, 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, an electrode group shown in FIG. 2 can be mentioned. That is, the S-shaped separator 3 is disposed on the inner periphery of the electrode group 5 again. The positive electrode 2 is disposed outside the S-shaped separator 3. Between the S-shaped separator 3 and the side surface of the positive electrode 2, a winding start end 4 a of the negative electrode 4 is arranged via another separator 3. 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 the 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.

As the electrode group 5, as shown in FIG. 3, an electrode group having a central portion having a structure in which the circumferential angle (θ) is 180 ° can be used.

In the electrode group having a structure in which the winding start end of the negative electrode faces the inner surface of the re-inner circumference positive electrode as shown in FIGS. 2 and 3 with a separator interposed therebetween, the winding start end of the positive electrode and the negative electrode Preferably, the circumferential angle (θ) corresponding to the positional deviation from the winding start end is 60 ° to 210 °.
This is due to the following reasons. If the peripheral 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 positive electrode that does not participate in the battery reaction may increase, which may cause inconvenience in battery design. More preferable peripheral 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. As the separator and the alkaline electrolyte, those similar to those described in the first alkaline secondary battery described above can be used.

(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 carried on a current collector. The binder includes particles mainly composed of a fluororesin having an average particle diameter of 0.2 μm or less. The current collector is a punched metal in which the shape of the hole is oblong, and a non-porous region is formed at least at an end of the winding start end and the winding end which is opposed to the positive electrode, and The oblong hole has a long diameter in the winding direction of the negative electrode.

As the active material and the binder, the same materials as those 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 oblong hole is an index of the degree of roller pressing. The ratio of the major axis to the minor axis of the oblong hole is 1.01 to
It is preferred to be in the range of 1.50. The ratio is 1.0
When the negative electrode is less than 1, the degree of pressurization is insufficient, and it may be difficult to sufficiently improve the flexibility, the active material filling density, and the active material holding power of the current collector. On the other hand, a negative electrode having the above ratio of more than 1.50 may be excessively pressurized at the time of roller pressing, and the current collector may be broken or the active material may be dropped. A more preferable ratio of the major axis to the minor axis of the oval 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 current collector preferably has an aperture ratio 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, the active material (host matrix of the active material), the binder, and the conductive agent are kneaded in the presence of water to prepare a paste. The paste is filled or applied to a punched metal having a circular hole shape and a non-porous region formed on at least one end perpendicular to the longitudinal direction. Continue to dry this,
The negative electrode A can be manufactured by performing roller pressing so that the circular hole extends in the longitudinal direction of the punched metal and deforms into an oval shape. Such a negative electrode,
Since it can be easily wound around 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 falling off 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 includes particles mainly composed of a fluororesin having an average particle diameter of 0.2 μm or less. The current collector is made of a punched metal having a Vickers hardness of 40 to 100 Hv, in which a non-porous region is formed at at least one end perpendicular to the longitudinal direction.

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

The Vickers hardness of the current collector is limited to the above range for the following reason. If the Vickers hardness is less than 40 Hv, the current collector may be excessively stretched during roller pressing, and the electrode density may be reduced. On the other hand, when the Vickers hardness exceeds 100 Hv, the flexibility of the current collector is reduced, and thus there is a possibility that cracks and falling off of the active material may occur when the spiral electrode group is manufactured. In addition, 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 be reduced. More preferred Vickers hardness is 50 to 8
The range is 0 Hv.

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

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

For the negative electrode B, for example, a paste is prepared by kneading an active material (host matrix of an active material), a binder, and a conductive agent in the presence of water, and the paste is filled in the current collector. After coating, it can be dried and then subjected to roller pressing to produce it.

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

Examples of the auxiliary separator include a nonwoven fabric made of a polyolefin fiber, a nonwoven fabric made of a nylon fiber, and a nonwoven fabric made of a mixture of a polyolefin fiber and a nylon fiber. Examples of the polyolefin fiber include a polypropylene fiber and a polyethylene fiber. It is preferable that the surface of the polyolefin fiber is subjected to a hydrophilic treatment.

(2) Positive Electrode As the positive electrode, the following four types of positive electrodes 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 includes particles mainly composed of a fluororesin having an average particle diameter of 0.2 μm or less. The current collector is a punched metal having an oval hole shape and a non-porous region formed on at least one end perpendicular to the longitudinal direction. The hole has a major axis in the longitudinal direction of the current collector.

Examples of the active material and the binder include those similar to those described in the first positive electrode.

In the current collector, the ratio of the major axis to the minor axis of the oblong hole is an index of the degree of roller pressing. The ratio of the major axis to the minor axis of the oblong hole is 1.01 to
It is preferred to be 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 active material filling density, and the active material holding power of the current collector. On the other hand, if the ratio exceeds 1.50, there is a possibility that the pressure may be excessively applied during roller pressing, and the current collector may be broken or the active material may fall off. A 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 current collector preferably has an aperture ratio of 30 to 70% (more preferably 40 to 65%).

The positive electrode A can be manufactured, 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 a non-porous region formed on at least one end perpendicular to the longitudinal direction. . This is dried, and the positive electrode A is manufactured by applying a roller press so that the circular hole extends in the longitudinal direction of the punched metal and deforms into an oval shape. Such a positive electrode can be easily wound around an axis perpendicular to the longitudinal direction, so that cracks at the time of producing the spiral electrode group and falling of the active material can be avoided.

Examples of the conductive agent include those similar to those described in the first positive electrode.

<Positive Electrode B> The positive electrode B has the same structure as the above-described positive electrode A, except that it does not contain, as a binder, particles mainly composed of a fluororesin having an average particle diameter of 0.2 μm or less.

<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 includes particles mainly composed of a fluororesin having an average particle diameter of 0.2 μm or less. The current collector has a non-porous region formed on at least one end perpendicular to the longitudinal direction, and is made of punched metal having a Vickers hardness of 40 to 100 Hv.

Examples of the active material and the binder include those similar to those described in the first positive electrode.

In the current collector, the Vickers hardness is limited to the above range for the following reason. If the Vickers hardness is less than 40 Hv, the current collector may be excessively stretched during roller pressing, and the electrode density may be reduced. On the other hand, when the Vickers hardness exceeds 100 Hv, the flexibility of the current collector is reduced, and thus there is a possibility that cracks and falling off of the active material may occur when the spiral electrode group is manufactured. In addition, 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 be reduced. More preferred 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 current collector preferably has an aperture ratio in the range of 30 to 70% (more preferably 40 to 65%).

The positive electrode C is prepared, for example, by kneading an active material, a binder, and a conductive agent in the presence of water to prepare a paste, filling or applying the paste to the current collector, and then drying the paste. , By applying a roller press.

Examples of the conductive agent include those similar to those described for the first positive electrode.

<Positive Electrode D> The positive electrode D has the same configuration as the above-described positive electrode C except that it does not contain, as a binder, particles mainly composed of a fluororesin having an average particle diameter of 0.2 μm or less.

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

Examples of the auxiliary separator include the same as those described above. A third alkaline secondary battery according to the present invention is a paste-type negative electrode including a hydrogen storage alloy, polytetrafluoroethylene, and 0.01 to 1.0 part by weight of a surfactant based on 100 parts by weight of the hydrogen storage alloy. , A positive electrode, and an alkaline electrolyte.

Such an alkaline secondary battery can have the cylindrical structure shown in FIG. Alternatively, the separator may be interposed between the plurality of negative electrodes and the plurality of positive electrodes to form a laminate, and the laminate may be housed in a bottomed rectangular cylindrical 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 first alkaline secondary battery can be used.

Hereinafter, the paste type negative electrode and the positive electrode will be described.

(1) Paste-type negative electrode The paste-type negative electrode is, for example, as described in (I) to (III) below.
).

(I) A hydrogen storage alloy powder, a binder containing a dispersion of unfired 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 prepared by filling or coating an electric body, drying, and pressing.

(II) After kneading the hydrogen-absorbing alloy powder, the conductive material and the hydrophilic polymer in the presence of water, adding an aqueous solution of a surfactant and kneading, and further sintering the unfired polytetrafluoroethylene particles. A paste is prepared by adding and kneading the paste, and the paste is filled or coated with a current collector, dried, and subjected to pressure molding to produce the negative electrode.

(III) After 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 and filling or applying the paste to a current collector, the paste is dried and subjected to pressure molding to produce the negative electrode.

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

The binder may be formed only of unfired polytetrafluoroethylene particles, but may contain another polymer such as a hydrophilic polymer.
Examples of the polymer used in combination with the polytetrafluoroethylene particles include the same polymers as described in the first negative electrode.

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

The unfired polytetrafluoroethylene particles having a particle size in the above range preferably have a standard specific gravity (SSG) in the range of 2.1 to 2.3 for the same reason as described above. A more preferred standard specific gravity is 2.15.
範 囲 2.25.

The amount of the polytetrafluoroethylene particles 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 addition amount is in the range of 1.0 to 3.0 parts by weight based on 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 a nonionic surfactant, an anionic surfactant, a cationic surfactant, and an amphoteric surfactant.

The content of the surfactant is limited to the above range for the following reason. If the content is less than 0.01 part 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, if the content exceeds 1.0 part by weight with respect to 100 parts by weight of the hydrogen storage alloy, the wettability of the negative electrode increases, so that the water repellency of the negative electrode decreases,
The three-phase interface amount may be insufficient. A more preferred content is in the range of 0.03 parts by weight to 0.5 parts by weight.

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

The first alkaline secondary battery according to the present invention, which has been described in detail, collects a binder containing particles mainly composed of a fluororesin having an average particle diameter of 0.2 μm or less and a paste containing an active material. And a first positive electrode configured to be held by an electric body.
The fluororesin particles have a conventionally used particle size of 0.1.
It has a higher specific surface area than polytetrafluoroethylene particles of 4 μm or more, and can be uniformly dispersed in the positive electrode paste. For this reason, the adhesiveness between the active material and the current collector can be significantly improved, and the falling off of the active material during battery assembly or during a charge / discharge cycle can be suppressed or avoided. In addition, since the amount of the binder used can be reduced (for example, 40 to 70% of the conventional amount),
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, the capacity of the positive electrode can be improved, so that an alkaline secondary battery having significantly improved discharge capacity and cycle life can be provided.

Further, even with low molecular weight polytetrafluoroethylene having a low degree of fiberization, sufficient adhesiveness can be ensured, so that the types of usable polytetrafluoroethylene can be increased (usable standard specific gravity). Can be expanded to 2.1 to 2.3), and the manufacturing cost of the paste-type positive electrode can be reduced.

Further, the first alkaline secondary battery according to the present invention is characterized in that a paste containing a binder and an active material containing particles mainly composed of a fluororesin having an average particle diameter of 0.2 μm or less is used as a current collector. Is provided. 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 active material density of the negative electrode are improved. be able to. As a result, the capacity of the negative electrode can be improved, so that an alkaline secondary battery having significantly improved discharge capacity and cycle life can be provided.

Further, since the water repellency is imparted uniformly by the fluororesin particles in the negative electrode, a three-phase interface can be uniformly formed as a whole, and the negative electrode is necessarily generated from the positive electrode when overcharged. Oxygen gas can be quickly absorbed. Therefore, the alkaline secondary battery provided with the negative electrode can suppress the rise of the internal pressure at the time of overcharge and improve the charge / discharge cycle life.

Further, since the types of polytetrafluoroethylene which can be used can be increased, it is possible to reduce the production cost of the paste type negative electrode.

The first alkaline secondary battery according to the present invention comprises:
It has the first positive electrode and the first negative electrode described above. In such a secondary battery, the adhesion between the active material and the current collector and the energy density of both the positive electrode and the negative electrode can be increased, so that the discharge capacity can be improved. Further, since the oxygen gas absorbing performance of the negative electrode during overcharge can be improved, an increase in internal pressure during overcharge can be suppressed. Therefore, it is possible to provide an alkaline secondary battery having significantly improved discharge capacity and charge / discharge cycle life.

The second alkaline secondary battery according to the present invention comprises:
A collector is interposed between a negative electrode A and a positive electrode, in which a paste containing an active material and a binder containing particles mainly composed of a fluororesin having an average particle size of 0.2 μm or less is swirled with a separator interposed therebetween. It is provided with an electrode group produced by winding in a shape. The current collector of the negative electrode A is a punched metal having a non-porous region 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 is oval 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, the active material packing density and the active material holding power are determined. And it can be easily wound around a direction perpendicular to the longitudinal direction as an axis. For this reason, it is possible to wind the negative electrode and the positive electrode in close contact with each other with the separator interposed therebetween, and it is possible to avoid a non-uniform reaction caused by a decrease in the adhesiveness of the positive and negative electrodes. Also,
The active material can be prevented from falling off during the preparation of the spiral electrode group or during the charge / discharge reaction. As a result, the discharge capacity of the secondary battery can be improved, so that the cycle life can be improved. Furthermore, since the negative electrode can improve oxygen gas absorption performance, the secondary battery can suppress an increase in internal pressure during overcharge.

Since the punched metal of the negative electrode has a non-porous region at least at the end facing the positive electrode, it is possible to prevent the end from penetrating through the separator and coming into contact with the positive electrode. be able to. Therefore, it is possible to avoid occurrence of 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, a problem that occurs when the active material filling amount of the negative electrode is increased for the purpose of increasing the capacity, that is, a decrease in the winding property of the negative electrode, 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 in the volume of the electrode group housed in the container, thereby realizing a high capacity negative electrode and improving the discharge capacity. In addition, the cycle life can be improved by suppressing an increase in internal pressure during overcharge.

Further, in the secondary battery, as described above, an internal short circuit that occurs during the production of the electrode group or the housing of the electrode group can be effectively prevented. A spiral electrode group having a structure opposed to the electrode can be used. As a result, it is possible to take advantage of the advantage that the spiral electrode group can achieve high capacity, which is a feature of the spiral electrode group, so that the discharge capacity of the alkaline secondary battery can be dramatically improved.

That is, although the spiral electrode group having the above-described structure can achieve a high capacity, an internal short circuit easily occurs when the spiral electrode group is housed in a container with a high volume, and an internal short circuit easily occurs during a charge / discharge cycle. . In the alkaline secondary battery, the positive electrode swells as the charge / discharge cycle progresses, thereby shortening the distance between the positive electrode and the negative electrode. When such swelling occurs, if needle-like metal due to punched metal exists at the winding start end of the positive electrode, the needle-like metal penetrates through the separator and comes into contact with the negative electrode, so that an internal short circuit occurs. . By forming a non-porous region at least at the starting 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, an oval hole having a long diameter in the specific direction is opened as the current collector of the positive electrode, and at least one of the winding start end and the winding 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 can be 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 with a high volume. As a result, a high-capacity positive electrode can be realized, so that the capacity of the alkaline secondary battery can be increased.

Further, by using a binder containing particles mainly composed of a fluororesin having an average particle diameter of 0.2 μm or less as the binder for the positive electrode, the adhesion between the positive electrode material and the current collector is improved. Therefore, the effect of preventing the active material from falling off during winding can be enhanced. As a result, an alkaline secondary battery with significantly improved capacity and cycle characteristics can be provided.

The second alkaline secondary battery according to the present invention comprises:
A collector is interposed between a negative electrode B and a positive electrode, in which a paste containing an active material and a binder containing particles mainly composed of a fluororesin having an average particle size of 0.2 μm or less is swirled with a separator interposed therebetween. It is provided with an electrode group produced by winding in a shape. The current collector of the negative electrode B is made of a punched metal having a Vickers hardness of 40 to 100 Hv, in which a non-porous region is formed at least at an end of the winding start end and an end of the winding facing the positive electrode.

Since such a negative electrode is provided with the above-mentioned specific binder and current collector, it can be easily wound around an axis perpendicular to the longitudinal direction. For this reason, it is possible to wind the negative electrode and the positive electrode in close contact with each other with the separator interposed therebetween, and it is possible to avoid a non-uniform reaction caused by a decrease in the adhesiveness 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, so that the cycle life can be improved. Furthermore, since the negative electrode can improve oxygen gas absorption performance, the secondary battery can suppress an increase in internal pressure during overcharge.

By forming a non-porous region at least at the end of the punched metal of the negative electrode facing the positive electrode, it is possible to prevent the end from penetrating through the separator and contacting 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 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, a problem that occurs when the active material filling amount of the negative electrode is increased for the purpose of increasing the capacity, that is, a decrease in the winding property of the negative electrode, 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 in the capacity of the electrode group housed in the container, thereby realizing a high capacity negative electrode and improving the discharge capacity. In addition, the cycle life can be improved by suppressing an increase in internal pressure during overcharge.

Further, in the secondary battery, 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 is used to achieve a higher capacity alkaline battery. A secondary battery can be provided.

As the current collector of the positive electrode, a punched metal having a non-porous region formed at least at the end of the winding end and the end of the winding facing the negative electrode and having a specific Vickers hardness is used. By this, 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 placed in a container with a high volume. It is possible to prevent an internal short circuit that occurs when storing. Therefore, a high-capacity positive electrode can be realized, and the capacity of the alkaline secondary battery can be increased.

Further, by using a binder containing particles mainly composed of fluororesin having an average particle diameter of 0.2 μm or less as the binder for the positive electrode, the adhesion between the positive electrode material and the current collector is improved. Therefore, the effect of preventing the active material from falling off during winding can be enhanced. As a result, an alkaline secondary battery with significantly improved capacity and cycle characteristics can be provided.

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

Further, in the secondary battery, 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 is used to achieve a higher capacity alkaline battery. A secondary battery can be provided.

The third alkaline secondary battery according to the present invention comprises:
Positive electrode, hydrogen storage alloy, polytetrafluoroethylene and 0.01 to 100 parts by weight of the hydrogen storage alloy
A paste-type negative electrode containing 1.0 part by weight of a surfactant and an alkaline electrolyte are provided. Such a negative electrode can uniformly disperse polytetrafluoroethylene particles in the paste in the paste preparation step. As a result, the current-collector can firmly hold the hydrogen-absorbing alloy powder, so that the hydrogen-absorbing alloy powder can be prevented from falling off during battery assembly or during a charge / discharge cycle. At the same time, a uniform and sufficient amount of the three-phase interface can be formed on the negative electrode, so that the oxygen gas absorbing performance of the negative electrode during overcharge can be improved. Therefore, the capacity of the alkaline secondary battery including the negative electrode can be improved, the increase in internal pressure during overcharge can be suppressed, and the charge / discharge cycle life can be improved.

Further, in the method for manufacturing 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 an aqueous surfactant solution is added and kneaded. Further, a negative electrode is produced by a method comprising the steps of adding a paste of unfired polytetrafluoroethylene and kneading the mixture to prepare a paste, and filling or applying the paste to a current collector. According to such a method, the polytetrafluoroethylene particles can be uniformly dispersed in the paste without adding the polytetrafluoroethylene particles in the form of a dispersion in the paste preparation step. As a result, it is possible to avoid an additive such as an alkali 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 reduced. A high-capacity, long-life alkaline secondary battery provided with a negative electrode having excellent gas absorption performance and containing no impurities can be provided.

Further, in another method for manufacturing 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 calcination are performed. A negative electrode is prepared by a method including a step of preparing a paste by adding and kneading polytetrafluoroethylene particles, and a step of filling or applying the paste to a current collector. According to such a method, the polytetrafluoroethylene particles can be uniformly dispersed in the paste without adding the polytetrafluoroethylene particles in the form of a dispersion in the paste preparation step. As a result, it is possible to avoid an additive such as an alkali 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 reduced. High capacity with a negative electrode that has excellent gas absorption performance and does not contain impurities,
A long-life alkaline secondary battery can be provided.

[0152]

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

Example 1 <Preparation of Paste-Type Positive Electrode> A mixture of 90 parts by weight of nickel hydroxide powder and 10 parts by weight of cobalt oxide powder was added to carboxymethylcellulose 0.1% as a binder with respect to the nickel hydroxide powder. 3 parts by weight, average particle size of 0.
A suspension of unfired 2 μm polytetrafluoroethylene particles (standard specific gravity 2.2) (specific gravity 1.5, solid content 60% by weight) was converted to solid content 2.5 parts by weight and polyacrylic acid. A paste was prepared by adding 0.5 parts by weight, adding 45 parts by weight of pure water thereto and kneading them.
Subsequently, after filling this paste into a nickel-plated fiber substrate, the paste was further applied to both surfaces thereof,
The paste was dried, rolled by roller pressing, and a paste-type positive electrode was produced. The average particle size of the polytetrafluoroethylene particles was measured by the method described above.

<Preparation of Paste Type Negative Electrode> A 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 with respect to 100 parts by weight of the obtained alloy powder,
Dispersion of uncalcined polytetrafluoroethylene particles (standard specific gravity of 2.2) (carboxymethylcellulose (CMC) 0.125 parts by weight, average particle size 0.4 μm, specific gravity 1.5, solid content 60 wt%) In terms of solid content and 2.5 parts by weight of carbon powder as a conductive material.
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 separator made of a nonwoven fabric made of a polyolefin fiber subjected to a hydrophilizing treatment was interposed between the negative electrode and the positive electrode and spirally wound to form a spiral electrode group. Such an electrode group and 7N KOH
An electrolytic solution composed of 1N LiOH and 1N LiOH was housed in a cylindrical container having a bottom, and a cylindrical nickel-metal hydride secondary battery having an AA size and a nominal capacity of 1200 mAh was assembled.

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.

The operation of spirally winding the positive electrodes of the obtained secondary batteries of Example 1 and Comparative Example 1 was repeated five times, and then these positive electrodes were weighed and weighed compared to before the winding. The degree of shedding was measured by determining how much it decreased. The results are shown in Table 1 below, where the degree of shedding in Comparative Example 1 was 100.

The charge and discharge cycle of charging the secondary batteries of Example 1 and Comparative Example 1 at 150 mA at 1 CmA and then discharging at 1 CmA until the battery voltage reaches 1.0 V is repeated, and 1 CmA at each cycle. The discharge capacity is calculated from the time until the battery voltage reaches 1.0 V, and the number of cycles required until the discharge capacity decreases to 80% of the discharge capacity in the first cycle is obtained. The result is shown in Table 1 below. I will write it together.

[0159] As is clear from Table 1, a paste-type positive electrode comprising a current collector filled with a binder containing particles containing a fluororesin as a main component and having an average particle size of 0.2 μm or less and a paste containing an active material. The secondary battery of Example 1 provided with the positive electrode had a positive electrode active material trapping compared to the secondary battery of Comparative Example 1 using particles having a fluororesin as a main component having an average particle size exceeding 0.2 μm as a binder. 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 consisting of 90 parts by weight of nickel hydroxide powder and 10 parts by weight of cobalt oxide powder was mixed with 0.1% of carboxymethyl cellulose as a binder with respect to the nickel hydroxide powder. 3 parts by weight, average particle size of 0.
A 4 μm suspension of uncalcined polytetrafluoroethylene particles (standard specific gravity 2.2) (specific gravity 1.5, solid content 60% by weight) was converted to a solid content of 2.5 parts by weight and polyacrylic acid. A paste was prepared by adding 0.5 parts by weight, adding 45 parts by weight of pure water thereto and kneading them.
Subsequently, after filling this paste into a nickel-plated fiber substrate, the paste was further applied to both surfaces thereof,
The paste was dried, rolled by roller pressing, and a paste-type positive electrode was produced.

<Preparation of Paste-Type Negative Electrode> 0.5 part by weight of sodium polyacrylate and 0.125 part by weight of carboxymethyl cellulose (CMC) were added to 100 parts by weight of a hydrogen storage alloy powder having the same composition as in Example 1, Particle size is 0.
Dispersion of 2 μm unfired polytetrafluoroethylene particles (standard specific gravity 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.

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

The operation of spirally winding the obtained negative electrodes of the secondary batteries of Example 2 and Comparative Example 1 was repeated five times, and then these negative electrodes were weighed and weighed as compared with those before the winding. The degree of shedding was measured by determining how much it decreased. The results are shown in Table 2 below, where the falling degree of Comparative Example 1 was set to 100.

For the secondary battery of Example 2, the number of cycles required until the discharge capacity decreased to 80% of the first cycle discharge capacity was determined in the same manner as described above. Also described in 2. Table 2 shows Comparative Example 1
Is also described.

Further, the internal pressures of the secondary batteries of Example 2 and Comparative Example 1 were measured. The internal pressure of the battery was measured by storing 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 includes a battery case including a case main body 21 and a cap 22 made of acrylic resin. 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 internal pressure of the secondary batteries of Example 2 and Comparative Example 1 when charged at 480% with a current of 0.5 CmA was measured by such a battery internal pressure measuring apparatus, and the results are shown in Table 2 below. I do.

Table 2 Degree of detachment Cycle number 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} clear from Table 2, the average particle size of the binder was as follows. 0.
The secondary battery of Example 2 provided with a paste-type negative electrode using particles containing a fluororesin having a particle size of 2 μm or less as a main component was compared with Comparative Example 1 in terms of active material trapping power of the negative electrode, charge-discharge cycle life characteristics, and It can be seen that the internal pressure characteristics during overcharge are excellent.

Example 3 An electrode group was produced by spirally winding a separator similar to that of Example 1 between a positive electrode similar to that of Example 1 and a negative electrode similar to that of Example 2. Such an electrode group and the same electrolytic solution as in Example 1 were housed in a cylindrical container having a bottom to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

For the obtained secondary battery of Example 3, the maximum battery internal pressure at the time of overcharging was measured in the same manner as described above, and it was 3.6 kg / cm ² , which was lower than that of Comparative Example 1. Further, 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.

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 carboxymethylcellulose (CMC), and unfired polytetrafluoroethylene particles having an average particle diameter of 0.2 μm with respect to 100 parts by weight of the obtained alloy powder ( A dispersion having a specific gravity of 2.2) (specific gravity: 1.5, solid content: 60 wt%) is 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. Thus, a paste was prepared.

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

After the paste was applied to the current collector and dried, the paste was roll-pressed so that the circular hole extended in the longitudinal direction of the punched metal and was deformed into an oval shape. A formula negative electrode was produced.

As shown in FIG. 5, the obtained negative electrode 40
It has a structure in which a paste 43 is filled in a punched metal 42 having a non-porous region 41 formed at an end perpendicular to the longitudinal direction. Hole 44 opened in the punched metal 42
Is an oval, having a major diameter r in the longitudinal direction of the punched metal 42. The ratio of the major axis r to the minor axis of the hole 44 is 1.10.

<Preparation of Paste-Type Positive Electrode> A mixed powder consisting of 90 parts by weight of nickel hydroxide powder and 10 parts by weight of cobalt oxide powder was mixed with 0.3 part by weight of carboxymethyl cellulose as a binder with respect to the nickel hydroxide powder. A suspension of unfired polytetrafluoroethylene particles having an average particle diameter of 0.4 μm (specific gravity 1.5, solid content 60% by weight) was converted to 0.5 part by weight in terms of solid content, and Then, 0.3 parts by weight were added, and 45 parts by weight of pure water was added thereto and kneaded to prepare a paste. 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 subjected to a hydrophilic treatment is interposed between the negative electrode and the positive electrode and spirally wound to form a spiral having the structure shown in FIG. A shaped electrode group was produced. In the electrode group, a winding start end of the negative electrode faces a side surface of the positive electrode via a separator. The end of the negative electrode having a non-porous region of punched metal is located at the winding start end of the negative 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 negative electrode side surface. 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 1N
An NA LiOH electrolytic solution was housed in a bottomed cylindrical container to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

Example 5 A cylindrical nickel-metal hydride 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 oval hole of the punched metal of the negative electrode was changed to 1.01. Was.

Example 6 A cylindrical nickel-metal hydride 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 oval hole in the punched metal of the negative electrode was changed to 1.50. Was.

Comparative Example 2 A cylindrical nickel-metal hydride 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 of the oval holes in the punched metal of the negative electrode was changed so that the oval holes had a longer diameter in a direction perpendicular to the longitudinal direction of the punched metal. A cylindrical nickel-metal hydride secondary battery was assembled in the same manner as in Example 4.

Comparative Example 4 A cylindrical nickel-metal hydride secondary battery was assembled in the same manner as in Example 4 except that no non-porous region was provided in the punched metal of the negative electrode.

Comparative Example 5 A cylindrical nickel metal hydride 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.

The operation of spirally winding the negative electrodes of the obtained secondary batteries of Examples 4 to 6 and Comparative Examples 2 to 5 was repeated five times, and then these negative electrodes were weighed and before the winding. The degree of shedding was measured by determining how much the weight decreased in comparison. The results are shown in Table 3 below, assuming that the dropping 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 that had an internal short circuit at the time of assembly was examined, and the results are also shown in Table 3 below.

[0186] The internal pressures of the secondary batteries of Examples 4 to 6 and Comparative Examples 2, 3, and 5 were measured. 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 150% at 1 CmA, and then charged at 1 CmA.
The charge / discharge 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 for each cycle. The number of cycles required until the discharge capacity was reduced to 80% was determined, and the results are also shown in Table 4 below.

Table 4 Maximum Battery Internal Pressure Cycle Number 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. A negative electrode formed by filling a current collector with a paste containing particles containing a fluororesin as a main component, wherein the current collector has an oval hole shape, and a non-porous region at the end of winding. Is a punched metal, wherein the oval hole has a long diameter in the winding direction of the negative electrode, the secondary battery has a low drop-off degree, can avoid an internal short circuit at the time of assembly, at the time of overcharge Internal pressure rise can be suppressed, Cycle life is seen that for a long time.

On the other hand, the current collector was the same as in Example 4, but the secondary battery of Comparative Example 2 provided with a negative electrode in which the average particle size of the polytetrafluoroethylene particles contained in the paste was 0.4 μm. Shows that the internal pressure during overcharge is higher and the charge / discharge cycle life is shorter than in Examples 4 to 6.
On the other hand, a negative electrode similar to that of Example 4 was prepared except that the arrangement state of the oval holes of the current collector was set such that the oval holes had a major axis in a direction orthogonal to the longitudinal direction of the punched metal. It can be seen that the secondary battery of Comparative Example 3 provided had a larger amount of falling off, a higher internal pressure during overcharge, and a shorter charge / discharge cycle life than 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 caused an internal short circuit at the time of assembly. Comparative Example 5 including a paste containing a styrene-butadiene copolymer as a binder and a negative electrode made of the punched metal filled with the paste and having a non-porous region formed at the winding start end. It can be seen that the secondary batteries have a higher degree of dropping, higher internal pressure during overcharge and shorter cycle life than Examples 4 to 6. The remarkably poor internal pressure characteristics at the time of overcharging is due to insufficient water repellency of the negative electrode due to the use of a styrene-butadiene copolymer as a binder. Comparative Example 5
When a suspension of polytetrafluoroethylene was applied to the surface of the negative electrode, the internal pressure during overcharge was still high, and to increase the oxygen gas absorption performance of the negative electrode, it was necessary to impart water repellency not only to the surface but also to the inside Is important.

Accordingly, in order to simultaneously avoid falling off of the active material at the time of winding, to suppress the internal pressure at the time of overcharging, and to extend the life,
It is understood 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 consisting 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 with respect to the nickel hydroxide powder. ), 0.3 parts by weight of polyacrylic acid and nitrile rubber (NB)
R) 3.0 parts by weight of a latex in terms of solid content was added,
A paste was prepared by adding and mixing 45 parts by weight of pure water to these. This paste is applied to a punched metal (thickness: 80 μm, aperture ratio: 50%) made of nickel having a circular hole shape and non-porous regions formed at both ends orthogonal to the longitudinal direction, and dried. A paste-type positive electrode was manufactured by roller pressing so that the hole extended in the longitudinal direction of the punched metal and was deformed into an oval shape.

In the obtained positive electrode, the oval 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 oval is 1.0.
It was 5.

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

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

Example 8 A cylindrical nickel-metal hydride 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> 0.3 parts by weight of carboxymethylcellulose as a binder was mixed with 90 parts by weight of nickel hydroxide powder and 10 parts by weight of cobalt oxide powder as a binder with respect to the nickel hydroxide powder. A dispersion (specific gravity 1.5, solid content 60 wt%) of unfired polytetrafluoroethylene particles (standard specific gravity 2.2) having an average particle size of 0.2 μm is 0.5 part by weight in terms of solid content. Then, 0.3 parts by weight of polyacrylic acid was added, and 45 parts by weight of pure water was added thereto, followed by kneading to prepare a paste. This paste is punched metal (having a thickness of 80 μm, having a thickness of 80 μm and having a non-porous region formed at both ends perpendicular to the longitudinal direction, having a circular hole shape.
After coating and drying (an aperture ratio of 50%), the paste-type positive electrode was manufactured by roller pressing so that the holes extended in the longitudinal direction of the punched metal and deformed into an oval shape.

In the obtained positive electrode, the oval 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 oval is 1.0.
It was 5.

Example 9 Except that the arrangement of the oval holes of the punched metal of the positive electrode was changed so that the oval holes had a longer diameter in a direction orthogonal to the longitudinal direction of the punched metal. A cylindrical nickel-metal hydride 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-out test as described above was performed.
Assuming that the degree of shedding was 100, Example 8 was 90 and Example 9 was 120.

When the number of batteries that had an internal short circuit during assembly was examined for 200 secondary batteries of Examples 7 to 9, no internal short circuit occurred during assembly of any of the secondary batteries. When 200 cylindrical nickel-metal hydride secondary batteries were assembled in the same manner as in Example 7 except that the non-porous region was not provided in the punched metal of the positive electrode, five batteries with internal short-circuit occurred. Was.

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

Example 10 A cylindrical nickel-metal hydride secondary battery similar to that of Example 4 was assembled, except that the negative electrode described below was used.

<Preparation of Paste-Type Negative Electrode> 0.5 part by weight of sodium polyacrylate and 100 parts by weight of hydrogen storage alloy
MC) Dispersion (specific gravity 1.5, solid content 6) of unfired polytetrafluoroethylene particles (standard specific gravity 2.2) having an average particle size of 0.125 parts by weight and an average particle size of 0.2 μm
(0 wt%) in terms of solid content and 1.0 part by weight of carbon powder as a conductive material were mixed with 50 parts by weight of water to prepare a paste. This paste was used as a current collector to form a punched metal made of nickel having a non-porous region formed at an end perpendicular to the longitudinal direction (Vickers hardness: 75 Hv, thickness: 80 μm, aperture ratio: 50%).
%), Dried and then roller pressed to produce a paste type negative electrode.

Comparative Example 6 A cylindrical nickel-metal hydride 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-metal hydride 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-metal hydride 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-metal hydride secondary battery was assembled in the same manner as in Example 10, except that no non-porous region was provided in the punched metal of the negative electrode.

The operation of spirally winding the negative electrodes of the obtained secondary batteries of Example 10 and Comparative Examples 6 to 9 was repeated five times, and then these negative electrodes were weighed and compared with those before the winding. The degree of shedding was determined by determining how much the weight was reduced. The results are shown in Table 5 below, where the degree of shedding in Example 10 was 100.

[0209] For 200 secondary batteries of Example 10 and Comparative Examples 6 to 9, the number of batteries that had an internal short circuit during assembly was examined. 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 Cycle Number 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 clear from Tables 5 and 6, the negative electrode formed by filling the current collector with the secondary battery of Example 10, that is, 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-porous 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 falling off, can avoid an internal short circuit at the time of assembly, can suppress an increase in internal pressure at the time of overcharge, and has a long cycle life.

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

Example 11 <Preparation of Paste-Type Positive Electrode> A mixed powder comprising 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 with respect to the nickel hydroxide powder. ), 0.3 parts by weight of polyacrylic acid and nitrile rubber (NB)
R) 3.0 parts by weight of a latex in terms of solid content was added,
A paste was prepared by adding and mixing 45 parts by weight of pure water to these. This paste is used as a current collector to form a punched metal (Vickers hardness of 75H) made of nickel having non-porous regions formed at both ends perpendicular to the longitudinal direction.
v, thickness 80 μm, aperture ratio 50%), dried, and then roller pressed to produce a paste-type negative electrode.

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

The above-mentioned electrode group and the same electrolytic solution as in Example 4 were housed in a bottomed cylindrical container to assemble the AA-size cylindrical nickel-metal hydride secondary battery having the structure shown in FIG. 1 described above.

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

<Preparation of Paste-Type Positive Electrode> A mixed powder consisting of 90 parts by weight of nickel hydroxide powder and 10 parts by weight of cobalt oxide powder was mixed with 0.3 part by weight of carboxymethylcellulose based on the nickel hydroxide powder and average particle diameter. Is 0.
Dispersion of 2 μm unfired polytetrafluoroethylene particles (standard specific gravity 2.2) (specific gravity 1.
5, a solid content of 60 wt%) was added in an amount of 0.5 part by weight in terms of solid content, and pure water was added in an amount of 45 parts by weight and kneaded to prepare a paste. This paste was used as a current collector to form a punched metal made of nickel (having a Vickers hardness of 7) having non-porous regions formed at both ends orthogonal to the longitudinal direction.
(5 Hv, thickness 80 μm, opening ratio 50%), dried, and then roller pressed to produce a paste type negative electrode.

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

With respect to the obtained positive electrodes of the secondary batteries of Examples 11 to 13, the same drop-out test was performed as described above, and the drop-out degree of Example 11 was set to 100.
0 and Example 13 was 110.

Further, the secondary batteries 200 of Examples 11 to 13 were used.
When the number of batteries that had an internal short circuit during assembly was examined, no internal short circuit occurred during assembly of any of the secondary batteries. When 200 cylindrical nickel-metal hydride secondary batteries were assembled in the same manner as in Example 11 except that the non-porous region was not provided in the punched metal of the positive electrode, three batteries with internal short-circuit occurred. 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. The secondary battery of Example 11 was 360, and the secondary battery of Example 12 was At 410, the secondary battery of Example 13 is 2
90.

Example 14 A cylindrical nickel-metal hydride secondary battery similar to that of Example 11 was assembled except that a negative electrode similar to that of Example 4 and a positive electrode similar to that of Example 12 were used.

Example 15 A cylindrical nickel-metal hydride secondary battery similar to that of Example 11 was assembled except that a negative electrode similar to that of Example 10 and a positive electrode similar to that of Example 8 were used.

When the number of batteries that had an internal short circuit during assembly was examined for 200 secondary batteries of Examples 14 and 15, no internal short circuit occurred during assembly of any of the secondary batteries.

Further, the charge / discharge cycle life of the secondary batteries of Examples 14 and 15 was determined in the same manner as described above.
The number of secondary batteries of No. 5 was 460.

In the above Examples 4 to 15, the non-porous region was not provided at the winding end portion of the punched metal of the negative electrode, but the effect of avoiding an internal short circuit at the time of assembling and during the charge / discharge cycle was further improved. It is preferable to provide a non-perforated region at the end of the winding in order to increase the density.

Example 16 <Preparation of Paste-Type Positive Electrode> A mixed powder consisting 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 to the nickel hydroxide powder. ), 0.3 parts by weight of polyacrylic acid and nitrile rubber (NB)
R) 3.0 parts by weight of a latex in terms of solid content was added,
A paste was prepared by adding and mixing 45 parts by weight of pure water to these. 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 part by weight of sodium polyacrylate, 0.125 part by weight of carboxymethylcellulose (CMC) and 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. An aqueous solution of a polyoxyethylene alkyl phenyl ether as a surfactant was added to the solution in an amount of 0.01
After addition 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 unfired polytetrafluoroethylene particles (standard specific gravity: 2.2) and kneading. This paste was applied to punched metal, dried, and then roller pressed to produce a paste type negative electrode.

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

Example 17 The amount of the aqueous surfactant solution in terms of solid content was 0.5
A nickel-metal hydride secondary battery similar to that in Example 16 was assembled except that the amount was changed to parts by weight.

Example 18 The mixing amount of the aqueous surfactant solution in terms of solid content was 1.0
A nickel-metal hydride secondary battery similar to that in Example 16 was assembled except that the amount was changed to parts by weight.

Comparative Example 10 The mixing amount of the aqueous surfactant solution in terms of solid content was 0.0
A nickel-hydrogen secondary battery similar to that in Example 16 was assembled except that the amount was changed to 05 parts by weight.

Comparative Example 11 The blending amount of the aqueous surfactant solution in terms of solid content was 1.5.
A nickel-metal hydride secondary battery similar to that in Example 16 was assembled except that the amount was changed to parts by weight.

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

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

Table 7 Degree of detachment Cycle number 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 electrode containing the surfactant in the range of 0.01 to 1.0 part by weight with respect to part by weight, the content of the surfactant was It can be seen that the negative electrode has superior active material trapping power, charge / discharge cycle life characteristics, and internal pressure characteristics during overcharge as compared with the secondary batteries of Comparative Examples 10 and 11 in which the ratio exceeds the above range.

Example 19 A cylindrical nickel-metal hydride 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> With respect to 100 parts by weight of the hydrogen storage alloy powder having the same composition as in Example 1, 0.5 parts by weight of sodium polyacrylate, 0.125 parts by weight of carboxymethyl cellulose (CMC) and 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 a surfactant aqueous solution as in Example 16 in terms of solid content and kneading the mixture. . This paste was applied to punched metal, dried, and then roller pressed to produce a paste type negative electrode.

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

[0241]

As described above in detail, according to the paste type electrode and the alkaline secondary battery according to the present invention, the adhesion between the active material and the current collector can be improved, and the capacity and the service life can be increased. It has a remarkable effect such as that it can be achieved. Further, according to another paste-type electrode according to the present invention, it is possible to avoid internal short circuit, improve winding property and improve active material holding power of the current collector, and obtain a high-capacity alkaline secondary battery. , Etc. can be provided. Further, according to another alkaline secondary battery according to the present invention, the volume of the electrode group housed in the container can be increased without causing inconvenience such as an internal short circuit, and the internal pressure rise during overcharge is suppressed. And has remarkable effects such as improvement in capacity and charge / discharge cycle life. According to still another method of manufacturing an alkaline secondary battery and an alkaline secondary battery according to the present invention, it is possible to suppress or avoid the falling off of the active material during assembly or during a charge / discharge cycle, and to reduce the internal pressure during overcharge. It is possible to suppress a rise, and to achieve remarkable effects such as an increase in capacity and a longer life.

[Brief description of the 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 cross-sectional view showing a central part of an electrode group incorporated in the alkaline secondary battery of the present invention.

FIG. 3 is a cross-sectional view showing a central part 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]

DESCRIPTION OF SYMBOLS 1 ... container, 2 ... positive electrode, 3 ... separator, 4 ... negative electrode, 5 ...
Electrode group, 7 ... sealing plate.

Continuation of front page (56) References JP-A-8-339809 (JP, A) JP-A-7-73874 (JP, A) JP-A-5-41215 (JP, A) JP-A-7-161353 (JP) JP-A-59-25176 (JP, A) JP-A-9-147854 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 4/24-4/26 H01M 4/62 H01M 4/74

Claims (2)

(57) [Claims] 1. A method for manufacturing an alkaline secondary battery comprising a positive electrode, a negative electrode, and an alkaline electrolyte, comprising: kneading a hydrogen storage alloy, a conductive agent, and a hydrophilic binder in the presence of water. Preparing a paste by adding and kneading an aqueous solution of a surfactant, kneading and further adding and kneading unfired polytetrafluoroethylene particles having an average particle size of 0.2 μm or less ; Wherein the negative electrode is produced by a method comprising a step of filling or coating the negative electrode . 2. A method for producing an alkaline secondary battery comprising a positive electrode, a negative electrode, and an alkaline electrolyte, comprising: kneading a hydrogen storage alloy, a conductive agent, and a hydrophilic binder in the presence of water. , Surfactant aqueous solution and average particle size
Preparing the negative electrode by a method including a step of preparing a paste by adding and kneading unfired polytetrafluoroethylene particles of 0.2 μm or less, and a step of filling or applying the paste to a current collector; A method for manufacturing an alkaline secondary battery.