JPH08222265A - Manufacture of alkaline secondary battery - Google Patents

Abstract

PURPOSE: To provide a manufacturing method of an alkaline secondary battery by which a winding starting end part of a positive electrode can be restrained from swelling following the process of a charge-discharge cycle. CONSTITUTION: A core 12 having a groove 11 crossing the center is used, and after a part of a belt-like separator 5 is sandwiched by the groove 11 of the core 12, the core 12 is rotated, and a S-shaped bag is formed by the separator 5. After a tip part 3a of a negative electrode 3 is arranged in the S-shaped bag, it is wound at a desired peripheral angle. A positive electrode 4 is arranged in the separator 5 positioned outside the negative electrode 3 so that its tip part 4a is dislocated by a desired peripheral angle in the opposite direction of the winding direction from the tip part 3a of the negative electrode 3, and is further wound, and a spiral electrode group 1 is manufactured.

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 having a spiral electrode group, and more particularly to a method of manufacturing an alkaline secondary battery having an improved electrode group manufacturing process.

[0002]

2. Description of the Related Art A nickel-hydrogen secondary battery, which is an example of an alkaline secondary battery, uses a positive electrode having a structure in which a paste containing nickel hydroxide is filled in a current collector and a paste containing a hydrogen storage alloy as a current collector. It is provided with a negative electrode having a filled structure, a separator made of a synthetic resin fiber non-woven fabric, and an alkaline electrolyte. The nickel-hydrogen secondary battery has a structure in which an electrode group in which the separator is interposed between the positive electrode and the negative electrode and which is spirally wound, and the electrolytic solution are housed in a container. The container also serves as a negative electrode terminal as in a general alkaline secondary battery.

The nickel-hydrogen secondary battery is disclosed in JP-A-60
-100382, JP-A-60-130053, and JP-A-61-99278, the spiral-shaped electrode group prepared so that the outermost peripheral end is the end of the negative electrode is provided in the container. There is known a structure having a structure in which a current is collected by being housed inside and contacting the inner surface of the container with the negative electrode located at the outermost periphery. In this way, the structure in which the outermost peripheral end of the electrode group is the end of the negative electrode simplifies the manufacturing process of the secondary battery and ensures reliable current collection. In addition, since the reaction of reducing oxygen gas generated from the positive electrode to water at the negative electrode when the secondary battery is overcharged is efficiently performed, it is suppressed that the internal pressure of the secondary battery rises. Battery characteristics are improved.

Meanwhile, in an alkaline secondary battery having a positive electrode having a structure in which a current collector is filled with the paste containing nickel hydroxide described above, the positive electrode swells as the charging / discharging cycle progresses. The swelling of the positive electrode is caused by movement of the electrolytic solution,
It is caused by two things that are not related to the movement of the electrolytic solution. The electrolytic solution in the separator of the secondary battery moves to the positive electrode and the negative electrode as the charging / discharging cycle progresses, so that the positive electrode and the negative electrode absorb the electrolytic solution and swell. Further, the positive electrode also swells when the secondary battery is charged and discharged. After that, when discharged, the positive electrode returns to its original volume. However, as the charge / discharge cycle progresses, the volume that decreases during discharge decreases, and as a result, the positive electrode swells. With this positive electrode,
And when subjected to a charge-discharge cycle to a secondary battery having a structure in which the outermost peripheral end of the electrode group is the end of the negative electrode, the positive electrode located at a position away from the center of the electrode group, that is, both sides are separators. Since the position of the positive electrode facing the negative electrode with the negative electrode sandwiched is regulated by the negative electrode, the degree of swelling is small. However, since the position of the winding start end of the positive electrode is not regulated by the negative electrode, there is a problem that the degree of swelling increases. When the winding start end of the positive electrode swells, the thickness of the positive electrode near the winding start end becomes thicker toward the center of the electrode group, or the winding start end of the positive electrode bends toward the center of the electrode group. To do.
As a result, the distance between the vicinity of the winding start end of the positive electrode and the negative electrode facing the winding start end varies, so that the portion of the positive electrode that reacts with the negative electrode becomes local, and the capacity of the secondary battery decreases. There is a problem that the charge / discharge cycle life is shortened.

From the above, Japanese Patent Laid-Open No. 3-1330
In the publication of Japanese Patent No. 66, an electrode group having a structure in which the end portions of the hydrogen storage alloy electrode are located at the innermost peripheral edge and the outermost peripheral edge, respectively, is provided so that the hydrogen storage alloy electrode faces the entire surface of the nickel oxide electrode. It is disclosed that the swelling of the nickel oxide electrode is suppressed. The electrode group is manufactured by the method shown in FIG. As shown in FIG. 10A, a winding core 22 having a groove 21 formed in the central portion is used, and the central portion of the strip-shaped separator 23 is sandwiched between the 21 grooves of the winding core 22 so that the winding core 22 is, for example, half. 1 clockwise
The S-shaped bag is formed by the separator 23 by rotating / 2 rounds. As shown in FIG. 10B, after the end portion 25 of the hydrogen storage alloy electrode 24 is placed in the S-shaped bag, the winding core 22 is rotated by 1/2 turn. Figure 10
As shown in (c), the nickel oxide electrode 26 is provided on the separator 23 located on the outer side of the separators 23 located on both sides of the electrode 24 so that its end portion 27 faces the end portion 25 of the electrode 24. To place. Next, by winding these, the spiral electrode group 28 shown in FIG.
Is prepared.

However, in order to meet the recent demand for a battery having a high capacity and a high energy density, when the capacity of the nickel oxide electrode 26 is increased in the secondary battery having the above-mentioned structure, it is proportional to the increase. As a result, the degree of swelling of the electrode 26 increased. As a result, it becomes difficult to suppress the swelling of the vicinity of the winding start end portion 27 of the electrode 26 due to the progress of the charging / discharging cycle by the hydrogen storage alloy electrode 24 facing this portion. Therefore, the nickel oxide electrode 26 locally reacts with the hydrogen storage alloy electrode 24, and the capacity of the secondary battery is reduced. Further, since the electrolytic solution in the separator 23 moves to the positive electrode 26, the electrolytic solution in the separator 23 is significantly reduced, and the internal resistance of the secondary battery is increased. As a result, the secondary battery has a problem that the charge / discharge cycle life is significantly reduced.

[0007]

An object of the present invention is to provide a method for producing an alkaline secondary battery in which the swelling of the winding start end of the positive electrode is suppressed as the charge / discharge cycle progresses. Is.

[0008]

The method of the present invention is an alkaline secondary battery comprising a positive electrode having a structure in which a paste containing nickel hydroxide is filled in a current collector, a negative electrode, a separator, and an alkaline electrolyte. A battery is manufactured, a winding core having a groove that crosses the center is used, a part of the separator is sandwiched by the grooves of the winding core, and then the winding core is rotated to form an S-shaped bag with the separator. Forming step, arranging the tip portion of the negative electrode in the S-shaped bag, and then winding the tip portion at a desired circumferential angle; A spirally wound electrode group is produced by arranging the negative electrode so as to deviate from the tip end portion in a direction opposite to the winding direction by a desired circumferential angle, and further winding the electrode. Is.

In the step of forming the S-shaped bag,
After sandwiching a part of the separator in the groove of the winding core,
It is preferable to form an S-shaped bag with the separator by rotating the winding core 1/3 to 2/3.
The reason why the rotation circumference of the winding core is limited is as follows. When the rotation circumference is less than 1/3, the portion of the separator not interposed between the positive electrode and the negative electrode is reduced, and the amount of the spare electrolyte solution in the electrode group may be reduced. There is. On the other hand, the rotation circumference is 2 /
If it exceeds 3 turns, the volume of the separator existing near the center of the electrode group becomes too large, and the volume of the positive electrode and the negative electrode may be reduced.

The circumferential angle corresponding to the positional deviation between the tip of the negative electrode and the tip of the positive electrode is 60 ° to 120.
It is preferable to set it to °. This is due to the following reasons. When the circumferential angle is less than 60 °, in such an electrode group, a portion where the negative electrodes are overlapped with each other without sandwiching the positive electrode is reduced, so that it may be difficult to suppress the swelling of the tip portion. is there. In addition, since the adhesion between the vicinity of the tip of the negative electrode and the positive electrode facing it may decrease, the reactivity between the positive electrode and the negative electrode may decrease.
On the other hand, if the circumferential angle exceeds 120 °, the ratio of the portion not involved in the battery reaction to the entire electrode may increase, which may cause inconvenience in battery design.

It is preferable to cover the vicinity of the tip of the positive electrode with another separator that is folded in two. In particular, the length of the positive electrode coated with the bi-fold separator is preferably 10% to 50% of the total length of the positive electrode. This is due to the following reasons. When the length of the positive electrode coated with the separator is less than 10% of the total length of the positive electrode, the effect of suppressing the swelling of the tip portion of the positive electrode as the charge / discharge cycle progresses may not be observed. There is. On the other hand, if the length of the positive electrode covered with the bi-fold separator exceeds 50% of the total length of the positive electrode, the volume occupied by the separator in the electrode group becomes too large, and the absolute void in the battery may decrease. As a result, the volumes of the positive electrode and the negative electrode may be reduced. More preferably, the length of the positive electrode coated with the other separator is
It is 20% to 40% of the total length of the positive electrode.

Hereinafter, the alkaline secondary battery manufactured by the method according to the present invention will be described with reference to FIG. The spiral electrode group 1 produced by the method described above is housed in a cylindrical container 2 having a bottom. The negative electrode 3 is arranged on the outermost periphery of the electrode group 1 and is in electrical contact with the container 2. The positive electrode 4 faces the negative electrode 3 with a strip-shaped separator 5 interposed therebetween. The alkaline electrolyte is contained in the container 2. A circular sealing plate 6 having a hole 6a in the center is arranged in the upper opening of the container 2. The ring-shaped insulating gasket 7 is arranged in a compressed state between the peripheral edge of the sealing plate 6 and the inner surface of the upper opening of the container 2. The sealing plate 6 is airtightly fixed to the upper opening of the container 2 under the compression of the insulating gasket 7. The positive electrode lead 8 has one end connected to the positive electrode 4 and the other end connected to the lower surface of the sealing plate 6. The positive electrode terminal 9 having a hat shape is
It is attached on the sealing plate 6 so as to cover the hole 6a. The rubber safety valve 10 is arranged so as to close the hole 6a in the space surrounded by the sealing plate 6 and the positive electrode terminal 9.

For the positive electrode 4, a paste containing nickel hydroxide powder, a conductive agent, a binder, and water was prepared, the current collector was filled with the paste, and the paste was dried and pressure-molded. Then, it is manufactured by cutting into a desired size.

Examples of the conductive agent include cobalt compounds such as cobalt monoxide, dicobalt trioxide, and cobalt hydroxide. Examples of the binder include polytetrafluoroethylene, carboxymethyl cellulose, methyl cellulose, sodium polyacrylate, and polyvinyl alcohol.

The current collector has a sponge-like, fiber-like, or felt-like porous structure made of, for example, an alkali-resistant metal such as nickel or stainless steel or a resin plated with alkali-resistant nickel. Can be mentioned.

The negative electrode 3 is prepared by adding a conductive material to the negative electrode active material, kneading it with a binder and water to prepare a paste, filling the current collector with the paste, drying it, and then molding it. Manufactured.

Examples of the negative electrode active material include cadmium compounds such as cadmium metal and cadmium hydroxide, and hydrogen storage alloys. Above all, the hydrogen storage alloy is preferable because it can improve the capacity of the secondary battery as compared with the case where the cadmium compound is used. The hydrogen storage alloy is not particularly limited as long as it can store hydrogen electrochemically generated in the electrolytic solution and can easily release the stored hydrogen during discharge. For example, LaNi ₅ and MmNi ₅ (Mm is La,
Ce, Pr, Nd, Sm, etc. means a misch metal which is a mixture of lanthanum-based elements), LnNi ₅ (L
n; lanthanum-enriched misch metal), and some of these Nis are Al, Mn, Co, Ti, Cu, Zn, Z
Examples thereof include multi-element type elements substituted with elements such as r, Cr and B.

Examples of the conductive material include carbon black. The same binder as the positive electrode 4 can be used as the binder. Examples of the current collector include two-dimensional substrates such as punched metal, expanded metal, perforated rigid plate and nickel net, and three-dimensional substrates such as felt-like metal porous bodies and sponge-like metal porous bodies. You can

Examples of the separator 5 include a nonwoven fabric made of polyamide fiber and a nonwoven fabric made of polyolefin fiber such as polyethylene and polypropylene to which a hydrophilic functional group is added. When the vicinity of the tip of the positive electrode 4 is covered with another separator that is folded in two, the same material as that of the separator 5 can be used as the material of the separator that is folded in two.

As the alkaline electrolyte, it is possible to use, for example, a potassium hydroxide solution or a mixed solution of potassium hydroxide with one or both of sodium hydroxide and lithium hydroxide added.

[0021]

According to the method of manufacturing an alkaline secondary battery of the present invention, an S-shaped bag is formed by a strip-shaped separator with a winding core, and the tip of the negative electrode is placed in the S-shaped bag, The core is rotated by a desired angle. The positive electrode is placed on a separator located on the outer side of the separators arranged on both sides of the negative electrode such that the tip of the positive electrode lags the tip of the negative electrode by a desired circumferential angle, and these are wound to form a spiral electrode. By forming the group, the winding start end (tip) of the negative electrode can be arranged before the leading end of the positive electrode, that is, the winding start end. Therefore, since the positive electrode is not arranged between the negative electrode at the innermost circumference located ahead of the winding start end of the positive electrode and the negative electrode at the second circumference, the negative electrode at the innermost circumference and the second circumference. The negative electrode of the eye can be overlapped with the separator interposed therebetween. In other words, within the circumferential angle corresponding to the positional deviation between the winding start end of the negative electrode and the winding start end of the positive electrode, the innermost negative electrode and the negative electrode 2
The negative electrode of the circumference can be stacked without sandwiching the positive electrode therebetween. As a result, the vicinity of the winding start end of the positive electrode can be sandwiched between the negative electrode at the innermost periphery and the negative electrode at the second periphery with the overlapping portion of the negative electrodes as a fulcrum without sandwiching the positive electrode. That is, a clip can be formed by the innermost negative electrode and the second negative electrode, and the clip can sandwich the vicinity of the winding start end of the positive electrode. According to the conventional method, as shown in FIG. 11 described above, the winding start end of the negative electrode and the winding start end of the positive electrode are arranged at the same position as viewed from the center of the winding core. It is not possible to form a portion where the above-mentioned negative electrodes are overlapped with each other in a portion preceding the portion. Therefore, the vicinity of the winding start end of the positive electrode is supported only by the innermost circumference of the negative electrode and the second circumference of the negative electrode, so that the vicinity of the winding start end of the positive electrode is suppressed from swelling. Since the force of pushing is weak, the winding start end of the positive electrode swells as the charging / discharging cycle progresses. According to the method of the present invention, the vicinity of the winding start end of the positive electrode is pressed by the negative electrode having the innermost circumference on both side surfaces thereof and the negative electrode at the second circumference. It is possible to prevent the positive electrode from thickening as the charge / discharge cycle progresses, that is, the positive electrode from swelling in the thickness direction. Further, since the above-mentioned portion where the negative electrodes are overlapped with each other is arranged in front of the winding start end portion of the positive electrode, this portion serves as a stopper, and the winding start end portion of the positive electrode is accompanied by the progress of the charging / discharging cycle. It is possible to suppress bending of the electrode group toward the center. As a result, it is possible to prevent the distance between the positive electrode and the negative electrode from varying, so that the capacity of the secondary battery can be improved. Further, since the electrolytic solution in the separator can be prevented from moving to the positive electrode, it is possible to prevent the internal resistance of the secondary battery from increasing. Therefore, the charge / discharge cycle life of the secondary battery can be improved.

Further, by setting the circumferential angle corresponding to the positional deviation between the winding start end of the positive electrode and the winding start end of the negative electrode to be 60 ° to 120 °, the negative electrodes described above overlap each other. The part can be secured sufficiently.
Therefore, the pressing force applied to both sides of the winding start end of the positive electrode can be improved, and the strength of the overlapping portion of the negative electrode can be improved, so that the charging / discharging cycle of the winding start end of the positive electrode can be improved. It is possible to further suppress the swelling that accompanies the progress. Further, by setting the circumferential angle within the above range, the adhesion between the tip portion of the positive electrode, the tip portion of the negative electrode, and the separator interposed therebetween can be improved, and the entire negative electrode can be used as a battery. Can be involved in the reaction. As a result, the circumferential angle is 60 ° to 120.
By setting the angle to 0, the charge / discharge cycle life of the secondary battery can be further improved.

Further, by covering the vicinity of the winding start end of the positive electrode with another separator which is folded in two, the vicinity of the winding start end of the positive electrode is sandwiched by the separator of the two folds, and further, the innermost portion described above. It is sandwiched by the clip formed by the negative electrode of the circumference and the negative electrode of the second circumference. Therefore, the pressing force applied to both side surfaces of the positive electrode near the winding start end can be improved. Further, the two-fold separator is fixed between the positive electrode and the innermost negative electrode, and between the positive electrode and the second-round negative electrode, respectively, at portions facing the positive electrode both side surfaces. As a result, since the portion facing the winding start end portion of the two-fold separator is pulled in the winding direction of the winding core by the portions facing the both side surfaces, the winding start end portion of the positive electrode is formed by the two-fold separator. A pressing force can be applied. Therefore, the pressing force applied to both side surfaces of the positive electrode near the winding start end can be improved, and the pressing force can be applied to the winding start end of the positive electrode, so that the winding start end of the positive electrode is charged and discharged. Swelling can be prevented as the cycle progresses.
Therefore, the distance between the positive electrode and the negative electrode can be maintained constant, and the electrolytic solution in the separator can be prevented from moving to the positive electrode. In addition, since the amount of the separator can be increased by covering the end portion of the positive electrode with the folded separator in this manner, the amount of the electrolytic solution stored in the electrode group can be increased. If only the amount of the electrolytic solution is increased without increasing the amount of the separator, the electrode group cannot absorb all of the electrolytic solution at the initial stage of charge and discharge, and excess electrolytic solution is accumulated on the upper part of the electrode group. When gas is generated in the secondary battery due to overcharge or the like in the secondary battery and the explosion-proof function is activated, the electrolytic solution accumulated on the upper part of the electrode group may be discharged together with the gas. Therefore, the bi-folded separator can prevent swelling of the winding start end of the positive electrode, and also functions as a reservoir for the electrolytic solution, so that battery performance such as charge / discharge cycle life can be maintained without impairing safety. Can be significantly improved.

By covering the vicinity of the winding start end of the positive electrode with the folded separator, it is possible to reduce the occurrence of internal short circuit due to cracks generated in the positive electrode and the negative electrode. The positive electrode and the negative electrode have poor flexibility, and in particular, the positive electrode may crack when the winding radius at the beginning of winding is small. As a result, the cracked portion may pierce the separator interposed between the positive electrode and the negative electrode to cause an internal short circuit. By doubling the separator arranged near the winding start end of the positive electrode, a crack generated near the winding start end of the positive electrode or the negative electrode is interposed between the positive electrode and the negative electrode. Since the breakthrough of the separator can be suppressed, the internal short circuit can be reduced. Therefore, the yield can be improved.

[0025]

Embodiments of the present invention will now be described in detail with reference to the drawings. Example 1 First, 0.2% by weight of carboxymethylcellulose and 5% by weight of polytetrafluoroethylene were added to a mixture consisting of 100 parts by weight of nickel hydroxide powder and 11 parts by weight of cobalt monoxide, and 30% by weight of water was added thereto. Was added and kneaded to prepare a paste. After filling each of the pastes into a nickel-plated fiber substrate as a current collector and drying,
A positive electrode was produced by roller pressing and rolling.

100 parts by weight of a hydrogen storage alloy powder having a composition of LaNi _4.0 Co _0.4 Mn _0.3 Al _0.3 , 0.5 parts by weight of polytetrafluoroethylene powder, 1 part by weight of carbon powder, and 0 parts of carboxymethyl cellulose as a binder. A paste was prepared by adding .2 parts by weight and mixing with 55 parts by weight of water. The paste was applied to a punched metal, dried, and then pressure-molded to produce a negative electrode. In addition, a separator made of a polypropylene fiber non-woven fabric having a hydrophilic functional group was prepared.

Next, as shown in FIG. 2 (a), a core 12 having a groove 11 that traverses the center was used, and the central portion of the strip separator 5 was sandwiched between the grooves of the core 12. By rotating the winding core 12 by 1/2 counterclockwise, an S-shaped bag is formed by the separator 5 as shown in FIG. 2B. After the end portion 3a of the negative electrode 3 was placed in the S-shaped bag, the winding core 12 was rotated 3/4 round.

As shown in FIG. 2C, the positive electrode 4 was placed on the outer separator 5 among the separators 5 placed on both sides of the negative electrode 3. The end 4a of the positive electrode 4 was arranged so as to be displaced from the end 3a of the negative electrode 3 in a desired circumferential angle (θ) in a direction opposite to the winding direction of the winding core.
The circumferential angle θ, that is, the angle formed by the line connecting the end 3a of the negative electrode 3 and the center of the winding core 12 and the line connecting the end 4a of the positive electrode 4 and the center of the winding core 12 is 90. °.
Then, by winding these, the spiral electrode group 1 shown in FIG. 3 was produced.

After removing the winding core from the prepared electrode group, the electrode group was housed in a bottomed cylindrical container. 8.
An AA-sized nickel metal hydride secondary battery having a structure shown in FIG. 1 and having a nominal capacity of 1100 mAh was manufactured by accommodating and sealing an alkaline electrolyte composed of a 0 mol / l potassium hydroxide aqueous solution. Example 2 An S-shaped bag was formed from the separator 5 made of the same material as in Example 1 by the same method as in Example 1. After arranging the end portion 3a of the negative electrode 3 having the same configuration as in Example 1 in the S-shaped bag, the winding core 12 was rotated by 2/3. The positive electrode 4 having the same structure as that of the first embodiment is placed on the separator 5 located outside the negative electrode 3 such that the end portion 4a thereof deviates from the end portion 3a of the negative electrode 3 by 60 ° in the direction opposite to the winding direction of the winding core. I arranged it. Then, these were wound to produce the spiral electrode group 1 shown in FIG.

Using the produced electrode group 1 and the same electrolytic solution as in Example 1, the structure shown in FIG. 1 was used in the same manner as in Example 1 and the nominal capacity was 1100 mAh.
An A size nickel-hydrogen secondary battery was manufactured. Example 3 An S-shaped bag was formed from a separator made of the same material as in Example 1 by the same method as in Example 1. After arranging the end portion of the negative electrode having the same structure as in Example 1 in the S-shaped bag,
The core was rotated 5/6 rounds. A positive electrode having the same structure as that of the first embodiment is attached to the separator located outside the negative electrode, and the end of the positive electrode is placed in the direction opposite to the winding direction of the winding core from the end of the negative electrode.
They were arranged so as to be offset by 20 °. Then, these were wound to produce a spiral electrode group.

AA having the structure shown in FIG. 1 and having the nominal capacity of 1100 mAh was prepared by the same method as in Example 1 using the prepared electrode group and the same electrolytic solution as in Example 1.
A nickel-hydrogen secondary battery of a size was manufactured. Example 4 An S-shaped bag was formed from a separator made of the same material as in Example 1 by the same method as in Example 1. After arranging the end portion of the negative electrode having the same structure as in Example 1 in the S-shaped bag,
The core was rotated 1/12 round. A positive electrode having the same structure as in Example 1 was placed on the separator located outside the negative electrode such that the end of the positive electrode was offset from the end of the negative electrode by 30 ° in the direction opposite to the winding direction of the winding core. Then, these were wound to produce a spiral electrode group.

Using the prepared electrode group and the electrolytic solution similar to that of Example 1, the AA having the structure shown in FIG. 1 and the nominal capacity of 1100 mAh was obtained by the same method as in Example 1.
A nickel-hydrogen secondary battery of a size was manufactured. Example 5 An S-shaped bag was formed from a separator made of the same material as in Example 1 by the same method as in Example 1. After arranging the end portion of the negative electrode having the same structure as in Example 1 in the S-shaped bag,
The winding core was rotated once. A positive electrode having the same structure as in Example 1 was placed on the separator located outside the negative electrode, and the end portion of the positive electrode was 180 degrees from the end portion of the negative electrode in the direction opposite to the winding direction of the winding core.
They are arranged so that they are offset from each other. Then, these were wound to produce a spiral electrode group.

AA having the structure shown in FIG. 1 and having a nominal capacity of 1100 mAh was prepared in the same manner as in Example 1 using the prepared electrode group and the same electrolytic solution as in Example 1.
A nickel-hydrogen secondary battery of a size was manufactured.

By preparing the electrode group by such a method, as shown in FIGS. 3 and 4, the end portion 3a of the negative electrode 3 is wound in the winding direction more than the end portion 4a of the positive electrode 4. Since they can be advanced by the circumferential angle θ, the innermost negative electrode 3 and the second negative electrode 3 located in the region within the circumferential angle θ can be overlapped without sandwiching the positive electrode 4. As a result, since the vicinity of the end portion 4a of the positive electrode 4 can be sandwiched by the negative electrode 3 located at the innermost circumference and the negative electrode 3 at the second circumference with the overlapping portion serving as a fulcrum, the positive electrode near the end portion 4a. Pressing force can be applied to both sides. Therefore, it is possible to prevent the vicinity of the end 4a of the positive electrode 4 from swelling in the thickness direction thereof as the charge / discharge cycle progresses. Also,
Since the overlapping portion of the negative electrodes is arranged immediately before the end portion 4a, the position of the end portion 4a can be restricted by the overlapping portion. Therefore, it is possible to prevent the vicinity of the end 4a of the positive electrode 4 from swelling in the lengthwise direction thereof as the charging / discharging cycle progresses.

The following experiments confirmed the excellent characteristics of the secondary battery manufactured by the method according to the present invention. Comparative Example Using the positive electrode, the negative electrode, and the separator having the same configurations as in Example 1, the end portion 25 of the positive electrode 24 and the negative electrode 2 shown in FIG.
The spiral electrode group 28 shown in FIG. 11 described above was produced by a method in which the end portions 27 of 6 and 6 are arranged at the same position as viewed from the center of the winding core 22.

Using the prepared electrode group 28 and the same electrolytic solution as in Example 1, the structure shown in FIG. 1 was used in the same manner as in Example 1, and the nominal capacity was 1100 mAh. A nickel-hydrogen secondary battery was manufactured.

Each of the obtained secondary batteries of Examples 1 to 5 and Comparative Example was charged by -ΔV charge control with a current value of 1.0 C, and then the battery voltage became 1.0 V at a current of 0.2 C. The charging / discharging cycle of discharging was repeated 1000 times. The discharge capacity at this time was measured, the discharge capacity ratio was determined from these values (based on the nominal capacity), and the result is shown in FIG.

As is apparent from FIG. 5, the secondary batteries of Examples 1 to 5 in which the tip of the positive electrode is displaced from the tip of the negative electrode by a desired circumferential angle in the direction opposite to the winding direction, It can be seen that the discharge capacity is high over a long period of time. In addition, the secondary batteries of Examples 1 to 3 having the circumferential angle of 60 ° to 120 ° are longer than those of Example 4 having the circumferential angle of 30 ° and Example 5 having the circumferential angle of 180 °. It can be seen that the discharge capacity is high during the period. On the other hand, the secondary battery of the comparative example in which the tip of the positive electrode and the tip of the negative electrode are arranged at the same position when viewed from the center of the winding core has a discharge capacity higher than those of the secondary batteries of Examples 1 to 5. It can be seen that the value of is quickly reduced.

Further, the secondary batteries of Examples 1 to 5 and Comparative Example were charged by -ΔV charge control with a current value of 1.0 C and then discharged at a current of 0.2 C until the battery voltage became 1.0 V. The charging / discharging cycle was repeated 1000 times. The internal resistance at this time was measured, the internal resistance ratio was calculated from these values (based on the internal resistance in the first cycle), and the result is shown in FIG.

As is apparent from FIG. 6, the secondary batteries of Examples 1 to 5 have low internal resistance over a long period of time. In addition, the secondary batteries of Examples 1 to 3 having the circumferential angle of 60 ° to 120 ° are longer than those of Example 4 having the circumferential angle of 30 ° and Example 5 having the circumferential angle of 180 °. It can be seen that the internal resistance is low during the period. On the other hand, it can be seen that the secondary battery of the comparative example increases the internal resistance faster than the secondary batteries of Examples 1 to 5. Example 6 After forming an S-shaped bag with the separator 5 in the same manner as in Example 1, the end portion 3a of the negative electrode 3 similar to that in Example 1 was placed in the S-shaped bag. Subsequently, the winding core 12 was rotated on the same rotation circumference as in Example 1. Further, as shown in FIG. 7, the end portion 4a of the positive electrode 4 having the same configuration as that of Example 1 was covered with another two-folded separator 13 made of the same material as that of Example 1. The length of the positive electrode coated with the separator 13 corresponds to 20% of the total length of the positive electrode.

The positive electrode 4 was placed on the outer separator 5 among the separators 5 placed on both sides of the negative electrode 3. The outer end portion 14 of the positive electrode 4 is arranged so as to be displaced from the end portion 3a of the negative electrode 3 by a desired circumferential angle (θ) in a direction opposite to the winding direction of the winding core. The circumferential angle θ is 90 ° as in the first embodiment. Then, the spirally wound electrode group 1 was produced by winding these.

Using the prepared electrode group 1 and the electrolytic solution similar to that of Example 1, the structure shown in FIG. 1 described above and the nominal capacity of 1100 mAh were obtained by the same method as in Example 1.
An A size nickel-hydrogen secondary battery was manufactured.

By producing the electrode group by such a method, as shown in FIG. 7 described above, the vicinity of the end 4a of the positive electrode 4 can be sandwiched between the other separators 13, and further, the innermost portion can be formed. It can be sandwiched by a clip formed by the negative electrode 3 on the circumference and the negative electrode 3 on the second circumference. That is, since the vicinity of the end 4a of the positive electrode 4 is doubly sandwiched by the separator 13 and the negative electrode 3, the pressing force applied to both side surfaces of the positive electrode near the end 4a can be improved.
Therefore, it is possible to prevent the vicinity of the end portion 4a of the positive electrode 4 from swelling in the thickness direction thereof as the charging / discharging cycle progresses. Further, a portion of the separator 13 facing both side surfaces of the positive electrode is interposed and fixed between the separator 5 and the positive electrode 4. As a result, the portion of the separator 13 facing the end portion 4a is pulled in the winding direction of the winding core 12 by the portions of the separator 13 facing the both side surfaces of the positive electrode, so that a pressing force can be applied to the end portion 4a of the positive electrode 4. it can. Therefore, the end portion 4a of the positive electrode 4 is restricted in its position by the portion where the negative electrodes are overlapped with each other and is pressed by the separator 13, so that the end portion 4a swells in the lengthwise direction thereof as the charge / discharge cycle progresses. Is prevented.

The following experiment confirmed the excellent characteristics of the secondary battery of Example 6. The above-described cycle test was performed on the obtained secondary battery of Example 6, and the obtained discharge capacity ratio is shown in FIG. The data of the comparative example are also shown in FIG.

As is apparent from FIG. 8, the tip of the positive electrode is arranged so as to be displaced from the tip of the negative electrode by a desired circumferential angle in the direction opposite to the winding direction, and the vicinity of the tip of the positive electrode is folded in two. It can be seen that the secondary battery of Example 6 coated with another separator of No. 1 has a high discharge capacity over a remarkably long period of 1000 cycles. On the other hand, the secondary battery of the comparative example in which the tip of the positive electrode and the tip of the negative electrode are arranged at the same position when viewed from the center of the winding core has a lower discharge capacity than the secondary battery of Example 6. You can see that it is quick to do.

The cycle test described above was conducted on the secondary battery of Example 6, and the internal resistance ratios obtained are shown in FIG. Moreover, the data of the comparative example are also shown in FIG. As is clear from FIG. 9, the secondary battery of Example 6 has a low internal resistance over a remarkably long period of 1000 cycles. On the other hand, it can be seen that the secondary battery of the comparative example increases the internal resistance faster than the secondary battery of the example 6.

In the above-mentioned embodiment, the example applied to the nickel-hydrogen secondary battery has been described, but the present invention can also be applied to the nickel-cadmium secondary battery and the nickel-zinc secondary battery in the same manner.

[0048]

As described in detail above, according to the method for producing an alkaline secondary battery of the present invention, it is possible to prevent the tip portion of the positive electrode from swelling as the charge / discharge cycle progresses,
The distance between the positive electrode and the negative electrode can be suppressed from varying, the alkaline electrolyte in the separator can be prevented from moving to the positive electrode, and the charge / discharge cycle life can be improved. Has a remarkable effect.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing a manufacturing process according to the present invention.

FIG. 3 is a cross-sectional view showing a spiral electrode group manufactured in Example 1.

FIG. 4 is a cross-sectional view showing a spiral electrode group manufactured in Example 2.

FIG. 5 shows 100 charge / discharge cycles in Examples 1 to 5.
The characteristic view which shows the change of discharge capacity at the time of repeating 0 times.

FIG. 6 shows 100 charge / discharge cycles in Examples 1 to 5.
The characteristic view which shows the change of the internal resistance when repeating 0 times.

FIG. 7 is a cross-sectional view of a main part of a spiral electrode group manufactured in Example 6.

FIG. 8 is a characteristic diagram showing a change in discharge capacity when the charge / discharge cycle in Example 6 is repeated 1000 times.

FIG. 9 is a characteristic diagram showing changes in internal resistance when the charge / discharge cycle in Example 6 is repeated 1000 times.

FIG. 10 is a sectional view showing a conventional manufacturing process.

FIG. 11 is a cross-sectional view showing a spiral electrode group manufactured by a conventional method.

[Explanation of symbols]

3 ... Negative electrode, 3a ... Tip part, 4 ... Positive electrode, 4a ... Tip part, 5
... separator, 11 ... groove, 12 ... winding core.

Claims (3)

[Claims] 1. A method for producing an alkaline secondary battery, comprising: a positive electrode having a structure in which a paste containing nickel hydroxide is filled in a current collector; a negative electrode; a strip-shaped separator; and an alkaline electrolyte. Forming a S-shaped bag with the separator by rotating the winding core after sandwiching a part of the strip-shaped separator with the groove of the winding core using a winding core having a transverse groove; Placing the tip of the negative electrode in an S-shaped bag, and then winding the tip at a desired circumferential angle; and placing the positive electrode on a separator located outside the negative electrode and the tip of the negative electrode is the tip of the negative electrode. And a step of producing a spirally wound electrode group by arranging in a direction opposite to the winding direction with a desired circumferential angle deviation, and further winding the electrode group. . 2. A circumferential angle corresponding to a positional deviation between the tip portion of the negative electrode and the tip portion of the positive electrode is 60 ° to 12 °.
The method for producing an alkaline secondary battery according to claim 1, wherein the method is 0 °. 3. The method of manufacturing an alkaline secondary battery according to claim 1, wherein the vicinity of the tip of the positive electrode is covered with another separator that is folded in two.