JP3523775B2 - 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 method of manufacturing an alkaline secondary battery, which has an improved process of manufacturing an electrode group.

[0002]

2. Description of the Related Art In a hydrogen storage alloy, when a negative electrode containing the same is formed and an electrode such as a nickel electrode is used as a counter electrode (positive electrode) in an alkaline electrolyte, hydrogen ions are stored in the negative electrode during charging and discharged during discharging. The stored hydrogen ions are released from the negative electrode, and the released hydrogen ions are oxidized to return to water. Therefore, the hydrogen storage alloy is used as a negative electrode material for secondary batteries. A nickel-hydrogen secondary battery is known as an example of such a secondary battery. Since this nickel-hydrogen secondary battery has a high energy density, it has high volume efficiency, safe operation, and high reliability.

As one of typical constitutions adopted in nickel-hydrogen secondary batteries, an electromotive element (electrode group) having a constitution in which a positive electrode and a negative electrode are wound inside a battery outer can (container) through a separator. One having a configuration in which the above is sealed is mentioned.
Specifically, first, an active material such as nickel hydroxide powder was carried on a current collector such as a nickel fiber substrate, and a hydrogen storage alloy powder was carried on a current collector such as a nickel net. An electromotive element part (electrode group) is produced by winding a negative electrode having a structure and a separator made of a non-woven fabric made of polyolefin fiber subjected to a hydrophilic treatment between the negative electrode and the negative electrode. The obtained electromotive element part is housed in a battery outer can (container), an alkaline electrolyte is injected, and after connecting the electromotive element part and an external terminal, the opening of the outer can is sealed. By doing so, the secondary battery is obtained.

By the way, in recent years, there has been a demand for higher capacity of nickel-hydrogen secondary batteries, and in response to this higher capacity, the number of turns of the positive and negative electrodes forming the electromotive element and the thickness of the positive and negative electrodes themselves are increased. It has increased.

[0005]

However, when the volume of the electromotive element is increased, it is necessary to reduce the amount of the alkaline electrolyte, so that the fluctuation of the weight of the positive electrode, the negative electrode and the separator affects the battery characteristics. And a battery with stable performance cannot be provided.

That is, when the electromotive element portion is manufactured by combining the positive electrode, the negative electrode, and the separator, which have the largest manufacturing tolerance of weight, the space inside the outer can is reduced, so that gas leakage during overcharge causes liquid leakage. There is a fear. On the other hand, when the electromotive element part is manufactured by combining the positive electrode, the negative electrode, and the separator, which have the smallest manufacturing tolerance of weight, the binding degree of the obtained electromotive element part is reduced, and the electrolyte solution flow between the positive and negative electrodes is reduced. As a result, the battery characteristics, particularly the cycle life, are reduced. Among the positive and negative electrodes and the separator,
Although the weight of the separator is most likely to vary, controlling the weight of the separator to suppress the variation in the weight of the electrode group makes the manufacturing operation very complicated.

The present invention regulates the combination of positive and negative electrodes to suppress variations in charge / discharge cycle life that accompany high capacity and variations in safety at the time of gas generation due to rapid charging and the like. It is intended to provide a method for manufacturing a battery.

[0008]

In the method of manufacturing an alkaline secondary battery according to the present invention, the positive electrode is divided into two or more groups by weight and the negative electrode is divided into two or more groups by weight, and the two stages are When selecting one group from each of the above groups, those belonging to the minimum stage group and those belonging to the maximum stage group should not be combined, and the positive and negative electrodes of the combined group should be used to prepare the electrode group. It is characterized by doing.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An example of an alkaline secondary battery manufactured by the method of the present invention will be described below with reference to FIG. An electrode group 5 produced by winding a positive electrode 2 and a negative electrode 4 with a separator 3 interposed therebetween is housed in a bottomed cylindrical container 1. The negative electrode 4 is disposed on 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. Circular first sealing plate 7 having a hole 6 in the center
Are arranged in the upper opening of the container 1. The ring-shaped insulating gasket 8 is disposed between the peripheral edge of the sealing plate 7 and the inner surface of the upper opening of the container 1, and the sealing plate is attached to the container 1 by caulking to reduce the diameter of the upper opening inward. 7 is airtightly fixed via the gasket 8. The positive electrode lead 9 has one end connected to the positive electrode 2 and the other end connected to the lower surface of the sealing plate 7. The hat-shaped positive electrode terminal 10 is mounted on the sealing plate 7 so as to cover the hole 6. The rubber safety valve 11 has the hole 6 in the space surrounded by the sealing plate 7 and the positive electrode terminal 10.
It is arranged so as to block. The circular holding plate 12 made of an insulating material having a hole in the center is arranged on the positive electrode terminal 10 such that the protruding portion of the positive electrode terminal 10 projects from the hole of the holding plate 12. Exterior tube 13
Covers the peripheral edge of the pressing plate 12, the side surface of the container 1 and the peripheral edge of the bottom portion of the container 1.

The secondary battery can be manufactured, for example, by the method described below. (First Step) A positive electrode, a negative electrode, a separator and an alkaline electrolyte which have the structures described below and have weights within manufacturing tolerances are prepared.

1) Positive Electrode 2 This positive electrode 2 has a structure in which a mixture containing a metal oxide is carried on a current collector. For the positive electrode, for example, a metal oxide powder, a conductive agent and a binder are kneaded in the presence of water to prepare a paste, the current collector is filled with the paste, and the paste is dried and roll-formed. Manufactured by.

Examples of the metal oxide include nickel hydroxide. As the conductive agent,
Examples thereof include cobalt compounds such as cobalt hydroxide, cobalt monoxide, dicobalt trioxide, and metallic cobalt.

Examples of the binder include fluororesins (eg, polytetrafluoroethylene), carboxymethyl cellulose, methyl cellulose, polyacrylates (eg, sodium polyacrylate), hydroxymethyl cellulose, polyvinyl alcohol and the like. it can.

The current collector may be a net-like, sponge-like, fibrous, or felt-like conductive substrate made of an alkali-resistant material such as nickel, stainless steel, or nickel-plated resin.

2) Negative Electrode 4 This negative electrode 4 is prepared by kneading a negative electrode active material, a conductive material, a binder and water to prepare a paste, filling the paste into a conductive substrate, drying and then molding. Manufactured by.

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

Among them, the hydrogen storage alloy is preferable because it can improve the capacity of the storage battery as compared with the case of using the cadmium compound. The hydrogen storage alloy is not particularly limited as long as it can store hydrogen generated electrochemically in the electrolytic solution and can easily release the stored hydrogen during discharge. For example, LaNi ₅ , MmN
i ₅ (Mm is misch metal), LmNi ₅ (Lm is L
at least one selected from rare earth elements including a), and a part of Ni of these alloys is Al, Mn, Co, Ti, C
Examples thereof include multi-element type elements substituted with elements such as u, Zn, Zr, Cr and B, or TiNi type elements and TiFe type elements. In particular, the general formula LmNi _w Co _x Mn
_y Al _z (total value of atomic ratios w, x, y, z is 5.00 ≦
w + x + y + z ≦ 5.50) is preferable because the hydrogen storage alloy having a composition represented by the formula (5 + x + y + z ≦ 5.50) can suppress pulverization accompanying the progress of the charge / discharge cycle and improve the charge / discharge cycle life.

Examples of the conductive material include carbon black and graphite. Examples of the binder include polyacrylic acid salts such as sodium polyacrylate and potassium polyacrylate, fluororesins such as polytetrafluoroethylene (PTFE), and carboxymethyl cellulose (CMC).

As the conductive substrate, for example, a two-dimensional substrate such as punched metal, expanded metal, perforated rigid plate, nickel net, or a felt-like metal porous body,
A three-dimensional substrate such as a sponge-like metal porous body can be mentioned.

3) Separator This separator can be formed of, for example, a non-woven fabric made of polyolefin fibers or nylon fibers, a woven fabric made of the same fibers, or a composite sheet made of these non-woven fabrics and woven fabrics. When the separator is made of polyolefin fiber, it is preferably subjected to a hydrophilic treatment. As the hydrophilic treatment, for example, application of a surfactant, graft copolymerization of a vinyl monomer having a hydrophilic group, or the like can be adopted. In particular, the separator is preferably formed by graft-copolymerizing a vinyl monomer having a carboxyl group with a sheet-shaped material containing a polyolefin-based synthetic resin fiber.

The polyolefin synthetic resin fibers include fibers made of one type of polyolefin, core-sheath composite fibers in which a polyolefin fiber different from the polyolefin fibers is coated on the surface of a core material made of polyolefin fibers, and different polyolefins from each other. Examples thereof include a composite fiber having a split structure in which fibers are joined in a circular shape. Examples of the polyolefin include polyethylene and polypropylene.

Examples of the sheet-like material containing the polyolefin-based synthetic resin fiber include a non-woven fabric made of the above-mentioned polyolefin-based synthetic resin fiber, a woven fabric made of the same fiber, or a composite sheet formed by combining these non-woven fabrics and woven fabric. Can be mentioned. The non-woven fabric is produced by, for example, a dry method, a wet method, a spun bond method, a melt blow method, or the like.

The average fiber diameter of the polyolefin synthetic resin fibers is preferably in the range of 1 to 20 μm from the viewpoint of mechanical strength and prevention of short circuit between the positive electrode and the negative electrode. A more preferable range of the average fiber diameter is 3 to 15 μm.
m.

Examples of the vinyl monomer having a carboxyl group include acrylic acid, methacrylic acid, esters of the acrylic acid and the methacrylic acid, and the like. Among the vinyl monomers, acrylic acid is preferable.

4) Alkaline Electrolyte As the alkaline electrolyte, for example, potassium hydroxide, a mixture of sodium hydroxide and lithium hydroxide, a mixture of potassium hydroxide and lithium hydroxide, sodium hydroxide and lithium hydroxide. And the like. In these electrolytic solutions, the concentration of potassium hydroxide is preferably in the range of 2.0 to 6.0 N, and the concentration of sodium hydroxide is 1.0 to 6.0 N (more preferably 2.0 to 5.0 N). The concentration of lithium hydroxide is preferably 0.3 to 2.0 N (more preferably 0.5 to 1.5 N). (Second Step) The positive electrode is divided into two or more groups by weight and the negative electrode is divided into two or more groups by weight. One group is selected from each of the obtained two or more groups, and the selected groups are combined with each other. This combination should not be a combination of groups in the minimum stage and groups in the maximum stage.

An example of weight selection of the positive and negative electrodes will be described with reference to FIGS. (First sorting method) When the standard weight is W ₁ , a large number of positive electrodes whose weight is within the manufacturing tolerance range (W ₁ ± a%) are prepared, and the weight range is divided into two equal parts. The smaller one is the first group and the larger one is the second group. On the other hand, the standard weight is W ₂
In this case, a large number of negative electrodes whose weight is within the manufacturing tolerance range (W ₂ ± b%) are prepared, the weight range is divided into two, the smaller weight range is the a group, and the larger weight range is the Group b. As shown in FIG. 2, the positive electrodes belonging to the first group and the negative electrodes belonging to the b group are combined, and the positive electrodes belonging to the second group and the negative electrodes belonging to the a group are combined.

(Second Selection Method) As shown in FIG. 3, when the standard weight is W ₁ , the weight is within the manufacturing tolerance (W
₁ ± a%), prepare a large number of positive electrodes, divide the weight range into three, and divide the weight region in order from the smallest group I, group II.
Group III. On the other hand, when the standard weight is set to W ₂ , prepare a large number of negative electrodes whose weight is within the manufacturing tolerance range (W ₂ ± b%), divide the weight range into three equally, and from the smaller weight range The r-th group, the s-th group, and the t-th group are set in order. As shown in FIG. 4, positive electrodes belonging to group I and negative electrodes belonging to group t are combined, positive electrodes belonging to group II and negative electrodes belonging to group s are combined, and positive electrodes belonging to group III and A negative electrode belonging to the r group is combined.

(Third sorting method) As shown in FIG. 5, when the standard weight is W ₁ , the weight is within the manufacturing tolerance (W
₁ ± a%), and prepare a large number of positive electrodes with a weight range of 1:
It is divided into 3 parts of 2: 1 (the small weight range and the large weight range are respectively 1), and the i-th
The group, group ii, and group iii. On the other hand, assuming that the standard weight is W ₂ , we prepare a large number of negative electrodes whose weight is within the manufacturing tolerance range (W ₂ ± b%), and divide the weight range into 3 parts of 1: 2: 1 (small weight). And the range of large weight are 1), and the x-th group, the y-th group, and the z-th group are arranged in order from the smaller one. As shown in FIG. 6, the positive electrode belonging to the i-th group and the z-th
A negative electrode belonging to group ii is combined, a positive electrode belonging to group ii is combined with a negative electrode belonging to group y, and a positive electrode belonging to group iii and a negative electrode belonging to group x are combined.

(Third step) An electrode group is prepared with a separator interposed between the positive electrode and the negative electrode belonging to the selected group.

(Fourth Step) The electrode group and the alkaline electrolyte are housed in a container, the electrode group is connected to an external terminal, and then sealed to assemble an alkaline secondary battery.

The amount C (cc) of the alkaline electrolyte is the void volume V (cc) in the electrode group determined by the following equation (1).
Of 72 to 80% is preferable. V (cc) = {V1- (V2 + V3 + V4)} (1) where V1 is the volume (cc) from the bottom surface of the container to the upper end of the electrode group when the electrode group is housed in the container, V
2 is the actual volume of the positive electrode (volume excluding porosity, c
c) and V3 are the actual volume of the negative electrode (volume excluding porosity, cc), and V4 is the actual volume of the separator (volume excluding porosity, cc).

The reason for limiting the amount of the electrolytic solution to the above range is as follows. The electrolytic solution amount C (c
When c) is less than 72% of the void volume V (cc) in the electrode group, the amount of electrolytic solution in the battery (particularly, the amount of electrolytic solution retained between the positive and negative electrodes) may decrease, and the charge / discharge cycle life may decrease. There is. On the other hand, when the amount C (cc) of the electrolyte solution exceeds 80% of the void volume V (cc) in the electrode group, the void volume in the container is insufficient and liquid leakage occurs when gas is generated by rapid charging or the like. May occur.

In FIG. 1 described above, the positive electrode and the negative electrode are spirally wound with a separator interposed therebetween to form an electrode group, and the electrode group is housed in a bottomed cylindrical container. Alternatively, the positive electrode and the negative electrode may be alternately laminated with a separator interposed therebetween to prepare an electrode group, and the electrode group may be housed in a bottomed rectangular tubular container.

As described above in detail, according to the method of manufacturing an alkaline secondary battery of the present invention, the positive electrode is divided into two or more groups by weight, and the negative electrode is divided into two or more groups by weight. When selecting one group from each of two or more stages, those belonging to the smallest stage group and those belonging to the largest stage group should not be combined, and the positive and negative electrodes of the combined group should be used for the electrode group. To make. As a result, even if the weight of the separator varies, it is possible to prevent the weight of the electrode group from becoming extremely large or small. Therefore, even when the amount of electrolyte must be reduced to increase the capacity, excellent charge / discharge cycle life can be maintained, and leakage when gas is generated due to rapid charging, etc. The liquid can be prevented.

Further, by setting the amount of the alkaline electrolyte to an amount corresponding to 72% to 80% of the void volume in the electrode group, the charge / discharge cycle life and the quick charge characteristics can be further improved.

[0036]

The preferred embodiments of the present invention will be described in detail below. Example 1 <Production of Positive Electrode> A mixture of 90 parts by weight of nickel hydroxide particles and 10 parts by weight of cobalt monoxide particles was added to a dispersion of 0.3 parts by weight of carboxymethyl cellulose as a binder and polytetrafluoroethylene (specific gravity: 1). 0.5, solid content 60 wt%) was added in an amount of 0.5 parts by weight in terms of solid content, and 45 parts by weight of water was further added and kneaded to prepare a paste. This paste was filled in a nickel-plated fiber substrate, and the paste was applied to both surfaces of the substrate, dried and roller pressed to prepare a paste-type nickel positive electrode. <Grouping of Positive Electrodes> From the obtained positive electrodes, those having a weight within the manufacturing tolerance range (the weight is within a range of W ₁ ± 2.4% when the standard value is W ₁ ) were selected. There were 100 positive electrodes having a weight within the above range. This weight range is W
₁ -2.4% to _W-1 range (first group of positive electrode), beyond the W _1, and a range of up to W ₁ + 2.4% (second group of positive electrode)
It was divided into two parts. There were 50 positive electrodes in the first group and 50 positive electrodes in the second group. <Production of negative electrode> LmNi _4.0 Co _0.4 Mn _0.3 Al
_0.3 (however, Lm is La-rich misch metal)
100 parts by weight of hydrogen storage alloy powder having the composition of 0.5 parts by weight, sodium polyacrylate 0.5 parts by weight, carboxymethyl cellulose 0.125 parts by weight, polytetrafluoroethylene dispersion (specific gravity 1.5, solid content 60 wt.
%) In terms of solid content, 2.5 parts by weight, carbon powder 1.0
A paste was prepared by adding 50 parts by weight of water and 50 parts by weight of water.
Then, the paste was applied to a punched metal, dried, and molded to prepare a paste-type hydrogen storage alloy negative electrode. <Grouping of Negative Electrodes> From the obtained negative electrodes, those having a weight within the manufacturing tolerance range (the weight is within the range of W ₂ ± 2.7% when the standard value is W ₂ ) were selected. There were 100 negative electrodes whose weight fell within the above range. This weight range is W
₂ -2.7% to _W-2 in the range between (the negative electrode of the first group a), beyond the W _2, and range up to W ₂ + 2.7% (negative electrode of the group b)
It was divided into two parts. There were 50 negative electrodes in the group a and 50 negative electrodes in the group b. <Preparation of Separator> Polypropylene resin is spun-bonded to have a fiber diameter of 10 μm.
A nonwoven fabric having a basis weight of 50 g / m ² and a thickness of 0.20 mm was produced. Subsequently, a first roll having a smooth surface and a second roll having a plurality of pinpoint-shaped concavities and convexities formed on the surface are arranged so as to face each other, and these rolls are rotated in the opposite directions, and the temperature is increased to 130 ° C. After heating, the non-woven fabric was passed between these rolls, pressed by the convex portions of the first roll and the second roll, and heat-bonded to perform embossing. Subsequently, the nonwoven fabric was irradiated with ultraviolet rays and then immersed in an aqueous solution of acrylic acid to graft-copolymerize an acrylic acid monomer. This non-woven fabric was washed to remove unreacted acrylic acid, dried, and cut to prepare many separators. The actual volume of the obtained separator was 0.9 cc for the minimum and 1.2 cc for the maximum. <Selection of Positive and Negative Electrodes and Production of Electrode Group> A maximum weight positive electrode among the first group positive electrodes and a maximum weight negative electrode among the b group negative electrodes were combined (Max-1 in FIG. 2). ).
A maximum actual volume (1.2 cc) of separator was interposed between the positive and negative electrodes, and the electrode group was produced by spirally winding. In addition, a positive electrode having the minimum weight of the positive electrodes of the first group and a negative electrode having the minimum weight of the negative electrodes of the b-th group are combined (Min-1 in FIG. 2), and the minimum actual weight is provided between the positive and negative electrodes. An electrode group was produced by spirally winding with a volume (0.9 cc) separator interposed. On the other hand, a maximum weight positive electrode of the second group of positive electrodes and a maximum weight negative electrode of the a-th group of negative electrodes are combined (Max-2 in FIG. 2), and a maximum actual weight is obtained between the positive and negative electrodes. Volume (1.2c
An electrode group was produced by winding in a spiral shape with the separator of c) interposed. In addition, a minimum weight positive electrode of the second group of positive electrodes and a minimum weight negative electrode of the a group of negative electrodes are combined (Min-2 in FIG. 2), and the minimum actual weight is placed between the positive and negative electrodes. An electrode group was produced by spirally winding with a volume (0.9 cc) separator interposed. The actual volumes of the positive and negative electrodes and the separator are shown in Table 1 below. <Assembly of Battery> After accommodating each electrode group in a cylindrical metal container having a bottom, an alkaline electrolyte solution of 3.9 cc consisting of 7N potassium hydroxide and 1N lithium hydroxide is accommodated in the container and the metal is Using each member such as the lid, a cylindrical nickel-hydrogen secondary battery of 4/3 A size and theoretical capacity of 3500 mAh was assembled.

For each secondary battery, the inner volume of the container (the height from the bottom of the container to the upper end of the electrode group (upper end of the separator)) V1 and the actual volumes of the positive electrode, the negative electrode and the separator (V2 to V4) Was calculated, and the void V of the electrode group was calculated from the above-mentioned formula (1). The ratio of the injection amount of the electrolytic solution to this void V was determined, and the results are also shown in Table 1 below.

Example 2 <Grouping of Positive Electrode> The weight of the positive electrode obtained in the same manner as in Example 1 was within the manufacturing tolerance (when the standard value was W ₁ , the weight was W ₁ ± 2.4%). (Within the range of 1). There were 100 positive electrodes having a weight within the above range. This weight range is W ₁ -2.4% ~ W ₁ -0.8%
Range (positive electrode of group I) and W ₁ -0.8% to a range of up to W ₁ + 0.8% (positive electrode of group II), W ₁
Range over + 0.8% and up to W ₁ + 2.4% (I
(Group II positive electrode). There are 20 positive electrodes in the group I, 60 positive electrodes in the group II, and 2 positive electrodes in the group III.
There were 0 of them. <Grouping of Negative Electrodes> The weight of the negative electrodes obtained in the same manner as in Example 1 was within the manufacturing tolerance (when the standard value was W ₂ , the weight was within the range of W ₂ ± 2.7%). I chose the ones. There were 100 negative electrodes whose weight fell within the above range. This weight range is W ₂ -2.7% to W ₂ -0.9%
Range (negative electrode of the r-th group), and a range exceeding W ₂ -0.9% and up to W ₂ + 0.9% (negative electrode of the s-th group), W ₂
It was divided into three parts in the range of more than + 0.9% and W ₂ + 2.7% (negative electrode of the t-th group). The r-th group had 20 negative electrodes, the s-th group had 60 negative electrodes, and the t-th group had 20 negative electrodes. <Production of Separator> In the same manner as in Example 1, a large number of separators having an actual volume within the range of 0.9 cc to 1.2 cc were produced. <Selection of Positive and Negative Electrodes and Production of Electrode Group> A maximum weight positive electrode of the positive electrodes of the I-th group and a maximum weight negative electrode of the negative electrodes of the t-th group were combined (Max-3 in FIG. 4). ).
A maximum actual volume (1.2 cc) of separator was interposed between the positive and negative electrodes, and the electrode group was produced by spirally winding. In addition, a positive electrode with the minimum weight of the positive electrodes of the I-th group and a negative electrode with the minimum weight of the negative electrodes of the t-th group are combined (Min-3 in FIG. 4), and the minimum actual weight is placed between the positive and negative electrodes. An electrode group was produced by spirally winding with a volume (0.9 cc) separator interposed.

A maximum weight positive electrode of the group II positive electrodes and a maximum weight negative electrode of the sth group negative electrodes are combined (Max-4 in FIG. 4), and a maximum weight is placed between the positive and negative electrodes. An electrode group was produced by spirally winding with an actual volume (1.2 cc) of separator interposed. Also, the above
The minimum weight positive electrode of the group II positive electrodes and the minimum weight negative electrode of the s-th group negative electrodes are combined (see Mi in FIG. 4).
n-4), the minimum actual volume (0.9 cc) between the positive and negative electrodes
An electrode group was produced by interposing the separator of and winding in a spiral shape.

Further, a positive electrode having the maximum weight of the positive electrodes of the group III and a negative electrode having the maximum weight of the negative electrodes of the r-th group are combined (Max-5 in FIG. 4), and the positive electrode and the negative electrode are connected. A maximum actual volume (1.2 cc) of the separator was interposed between the electrodes, and the electrode group was manufactured by spirally winding.
In addition, the positive electrode of the minimum weight of the positive electrode of the group III,
The negative electrode of the minimum weight among the negative electrodes of the r-th group is combined (Min-5 in FIG. 4), and a separator having a minimum actual volume (0.9 cc) is interposed between the positive and negative electrodes and wound in a spiral shape. By doing so, an electrode group was prepared. The actual volumes of the positive and negative electrodes and the separator are shown in Table 2 below. <Assembly of Battery> After accommodating each electrode group in a cylindrical metal container having a bottom, the same alkaline electrolyte as that of Example 1 is accommodated in the container and each member such as a metal lid is used. A cylindrical nickel-hydrogen secondary battery of / 3 A size and theoretical capacity of 3500 mAh was assembled.

For each secondary battery, the internal volume V1 of the container
And the actual volume of the positive electrode, negative electrode, and separator (V2 to V4)
Was calculated, and the void V of the electrode group was calculated from the above-mentioned formula (1). The ratio of the injection amount of the electrolytic solution to this void V was determined, and the results are also shown in Table 2 below.

Example 3 <Grouping of Positive Electrode> The weight of the positive electrode obtained in the same manner as in Example 1 was within the manufacturing tolerance (when the standard value was W ₁ , the weight was W ₁ ± 2.4%). (Within the range of 1). There were 100 positive electrodes having a weight within the above range. This weight range is W ₁ -2.4% ~ W ₁ -1.2%
Range (i-th positive electrode) and W ₁ -1.2% and up to W ₁ + 1.2% (ii-group positive electrode), W ₁ +
Range over 1.2% and up to W ₁ + 2.4% (No. ii
The positive electrode of group i) was divided into three parts. There are 10 positive electrodes in the i-th group, 80 positive electrodes in the ii-th group, and 10 positive electrodes in the iii-th group.
There was one. <Grouping of Negative Electrodes> The weight of the negative electrodes obtained in the same manner as in Example 1 was within the manufacturing tolerance (when the standard value was W ₂ , the weight was within the range of W ₂ ± 2.7%). I chose the ones. There were 100 negative electrodes whose weight fell within the above range. This weight range is W ₂ -2.7% to W ₂ -1.35
% Range (negative electrode of the x-th group) and range exceeding W ₂ −1.35% and up to W ₂ + 1.35% (negative electrode of the y-th group)
When, beyond the W ₂ + 1.35%, and was divided into three parts in the range of up to W ₂ + 1.35% (negative electrode of the z group). There were 10 negative electrodes in the x-th group, 80 negative electrodes in the y-th group, and 10 negative electrodes in the z-th group. <Production of Separator> In the same manner as in Example 1, a large number of separators having an actual volume within the range of 0.9 cc to 1.2 cc were produced. <Selection of Positive and Negative Electrodes and Fabrication of Electrode Group> A maximum weight positive electrode of the positive electrodes of the iith group and a maximum weight negative electrode of the negative electrodes of the yth group were combined (Max-6 in FIG. 6). ).
A maximum actual volume (1.2 cc) of separator was interposed between the positive and negative electrodes, and the electrode group was produced by spirally winding. In addition, a positive electrode having the minimum weight of the positive electrodes of the ii-th group and a negative electrode having the minimum weight of the negative electrodes of the y-th group are combined (Min-6 in FIG. 6), and the minimum actual weight is provided between the positive and negative electrodes. An electrode group was produced by spirally winding with a volume (0.9 cc) separator interposed. The actual volumes of the positive and negative electrodes and the separator are shown in Table 3 below. <Assembly of Battery> After accommodating each electrode group in a cylindrical metal container having a bottom, the same alkaline electrolyte as that of Example 1 is accommodated in the container and each member such as a metal lid is used. A cylindrical nickel-hydrogen secondary battery of / 3 A size and theoretical capacity of 3500 mAh was assembled.

For each secondary battery, the internal volume V1 of the container
And the actual volume of the positive electrode, negative electrode, and separator (V2 to V4)
Was calculated, and the void V of the electrode group was calculated from the above-mentioned formula (1). The ratio of the injection amount of the electrolytic solution to this void V was determined, and the results are also shown in Table 3 below.

Comparative Example <Combination of Positive and Negative Electrodes> The weight of the positive electrode obtained in the same manner as in Example 1 was within the manufacturing tolerance (when the standard value was W ₁ , the weight was W ₁ ± 2.4%. Those within the range) were selected. The total number of positive electrodes whose weight falls within the above range is 100.
There was one. In addition, the weight of the negative electrode obtained in the same manner as in Example 1 was within the range of manufacturing tolerance (when the standard value was W ₂ ,
₂ ± 2.7%) was selected. There were 100 negative electrodes whose weight fell within the above range. On the other hand, in the same manner as in Example 1, the actual volume is 0.9 cc to 1.2.
Many separators within the range of cc were produced. An electrode group was produced by arbitrarily combining these positive and negative electrodes and separators.

Here, the positive electrode having the maximum weight of the positive electrodes and the negative electrode having the maximum weight of the negative electrodes are combined (Max-7 in FIG. 7), and the maximum actual volume (1. An electrode group was produced by spirally winding with a separator of 2 cc) interposed. In addition, a positive electrode having the smallest weight of the positive electrodes and a negative electrode having the smallest weight of the negative electrodes are combined (Min-7 in FIG. 7), and a separator having a minimum actual volume (0.9 cc) is provided between the positive and negative electrodes. The electrode group was manufactured by interposing a coil and winding it in a spiral shape.
The actual volumes of the positive and negative electrodes and the separator are shown in Table 4 below. <Assembly of Battery> After accommodating each electrode group in a cylindrical metal container having a bottom, the same alkaline electrolyte as that of Example 1 is accommodated in the container and each member such as a metal lid is used. A cylindrical nickel-hydrogen secondary battery of / 3 A size and theoretical capacity of 3500 mAh was assembled.

For each secondary battery, the internal volume V1 of the container
And the actual volume of the positive electrode, negative electrode, and separator (V2 to V4)
Was calculated, and the void V of the electrode group was calculated from the above-mentioned formula (1). The ratio of the injection amount of the electrolytic solution to this void V was determined, and the results are also shown in Table 4 below.

The obtained Max-1 to 7 and Min-1 to
The secondary battery of No. 7 was aged for 24 hours in a constant temperature bath at 45 ° C. to carry out initial activation charging. After this, 2A
Then, after charging by -ΔV control, pause for 30 minutes, then 2A
Charge and discharge the battery until it reaches 1.0V with 5
Repeated 00 times. The presence / absence of electrolyte leakage in the 500th charge / discharge and the ratio of the 500th discharge capacity to the initial capacity were determined as a percentage, and the results are shown in Table 5 below.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

[Table 3]

[0051]

[Table 4]

[0052]

[Table 5]

As can be seen from Tables 1-5, Examples 1-
In the secondary battery of No. 3, an electrode group is manufactured by using the separator having the maximum weight and the positive and negative electrodes (Max-1 to 6) having the maximum weight in the group, or the separator having the minimum weight and the positive and negative electrodes having the minimum weight in the group. It can be seen that when an electrode group is manufactured by using (Min-1 to 6), liquid leakage due to charge / discharge can be prevented and the capacity retention rate (cycle life) can be improved. On the other hand, in the secondary battery of the comparative example, the maximum weight of the separator and the maximum weight of the positive and negative electrodes (Max
It can be seen that when -7) is combined, liquid leakage occurs, and when the minimum weight separator and the minimum weight of the positive and negative electrodes (Min-7) are combined, the capacity retention rate becomes significantly low. Moreover, when a nickel-hydrogen secondary battery was manufactured from the remaining positive and negative electrodes of Examples 1 to 3, the amount of the alkaline electrolyte in the void volume V of the electrode group was 72 to 80% in Example 1 and Example 2 Is 7
3 to 79%, Example 3 is in the range of 72 to 80%,
All the secondary batteries have a capacity retention rate of 8 after 500 cycles.
It was confirmed that 0% or more and no liquid leakage occurred after this cycle.

In the above-mentioned Examples 1 to 3,
Since the normal distribution of the weight distribution was 1, the distribution ratio in the weight range and the distribution ratio in the number of electrodes matched, but it is not necessary to match the distribution ratio in the weight range and the distribution ratio in the number of electrodes.

[0055]

As described in detail above, according to the method of manufacturing an alkaline secondary battery of the present invention, an appropriate charge / discharge cycle life is maintained and liquid leakage at the time of gas generation due to rapid charging is prevented. At the same time, a remarkable effect such as high capacity can be achieved.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing an example of an alkaline secondary battery manufactured by a method according to the present invention.

FIG. 2 is a schematic diagram showing an example of a combination of positive and negative electrodes in the method according to the present invention.

FIG. 3 is a schematic diagram showing an example of grouping of positive electrodes in the method according to the present invention.

FIG. 4 is a schematic diagram showing another example of a combination of positive and negative electrodes in the method according to the present invention.

FIG. 5 is a schematic diagram showing another example of grouping of positive electrodes in the method according to the present invention.

FIG. 6 is a schematic view showing still another example of a combination of positive and negative electrodes in the method according to the present invention.

FIG. 7 is a schematic diagram showing a combination of positive and negative electrodes in a comparative example.

[Explanation of symbols]

1 ... container, 2 ... Positive electrode 3 ... separator, 4 ... Negative electrode, 5 ... electrode group, 7 ... Sealing plate.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01M 10/28 H01M 4/26

Claims (3)

(57) [Claims] 1. A positive electrode is divided into two or more groups by weight and a negative electrode is divided into two or more groups by weight, and one group is selected from each of the two or more groups. A method for manufacturing an alkaline secondary battery, characterized in that an electrode group is produced by using positive and negative electrodes of a combined group so that those belonging to the same group and those belonging to the maximum stage group are not combined. 2. The method of manufacturing an alkaline secondary battery according to claim 1, wherein the weights of the positive electrode and the negative electrode are within manufacturing tolerances. 3. The alkaline secondary battery according to claim 1, wherein the electrode group and an amount of the alkaline electrolyte corresponding to 72 to 80% of the void volume in the electrode group are contained in a container. Production method.