JP4752401B2 - Manufacturing method of cylindrical alkaline storage battery - Google Patents

Description

  The present invention relates to a method for manufacturing a cylindrical alkaline storage battery, and more particularly to a technique capable of maintaining the utilization rate and life characteristics of nickel hydroxide even when the size is increased.

  In recent years, with the remarkable spread of information equipment, development of a secondary battery with high energy density has been demanded. In order to meet these demands, in the field of nickel cadmium batteries (hereinafter referred to as “nickel batteries”), in addition to increasing the capacity of sintered nickel cathodes, non-sintered nickel cathodes have been developed. The capacity has been increased by 30 to 60% with respect to a nickel-cadmium battery using a bonded nickel positive electrode. Furthermore, the development of a nickel-metal hydride storage battery (hereinafter referred to as Ni / MH) that uses a hydrogen storage alloy for the negative electrode and has a higher capacity than the nickel-cadmium battery is also progressing. A sintered nickel positive electrode is a sintered nickel porous body filled with nickel hydroxide powder at a high density, while a non-sintered nickel positive electrode has a high porosity such as a foamed nickel porous body or nickel fiber. A three-dimensional porous metal body is filled with nickel hydroxide powder at a high density.

As the capacity of the positive electrode is increased, studies on improving the utilization rate of the positive electrode have been made, and various additives have been used. As a general example, since nickel hydroxide as an active material has low conductivity, cobalt or a cobalt compound having high conductivity is added to improve the utilization rate. Cobalt and cobalt compounds react with hydroxide ions in the alkaline electrolyte to form water-soluble cobalt complex ions, which are oxidized during initial charge and deposited as conductive cobalt oxyhydroxide in the nickel positive electrode. Since the conductivity is increased between the nickel hydroxide particles as the active material and with the support by forming a network, the utilization factor of the active material can be improved. In order to enhance this effect, a method has been proposed in which the conductive network is optimized according to the initial charging conditions and the battery utilization rate is improved. Specifically, a method of performing an initial charging current at a rate of 1 to 20 hours (for example, Patent Document 1) and a method of performing initial charging in a high-temperature atmosphere (for example, Patent Document 2) have been proposed.
Japanese Patent No. 2940952 Japanese Patent Laid-Open No. 11-176431

  In recent years, from the viewpoint of environmental conservation, a cylindrical alkaline storage battery having a large capacity has been developed. Since these batteries have a large internal volume, there is a concern about non-uniform reaction in the batteries, but even with the techniques of Patent Documents 1 and 2, for example, in the case of a cylindrical alkaline storage battery having a battery capacity of 50 Ah or more, Since the oxidation efficiency of cobalt is insufficient, the positive electrode conductive network cannot be formed uniformly, and there is a problem that a high utilization rate cannot be obtained and the life is short.

  The present invention solves the above-mentioned problems, and even when the size is increased, a cylinder excellent in utilization rate and life characteristics of nickel hydroxide is obtained by increasing the oxidation efficiency of cobalt and uniformly forming a positive electrode conductive network. It aims at providing a type alkaline storage battery.

  In order to solve the above-mentioned problems, the cylindrical alkaline storage battery manufacturing method of the present invention is a cylindrical alkaline storage battery comprising a positive electrode containing nickel hydroxide and metallic cobalt and a negative electrode mainly composed of a hydrogen storage alloy. A first step of forming an electrode group with positive and negative electrodes and a separator, a second step of storing the electrode group and an electrolyte in a battery case to form a battery body, and initial charging while rotating the battery body It consists of a 3rd process, It is characterized by the above-mentioned.

  For example, in the case of a cylindrical alkaline storage battery with a battery capacity of 50 Ah or more, the electrolyte solution distribution in the battery body becomes non-uniform because the diameter of the battery case is extremely large, and the cobalt oxyhydroxide generated during the initial charge is in the positive electrode. Therefore, the conductive network of the positive electrode is not uniform, and the utilization rate is reduced and the life is shortened as compared with a cylindrical alkaline storage battery for consumer use having a small diameter. Here, when completing the initial charging and completing the cylindrical alkaline storage battery, the precursor battery body is rotated during the initial charging, so that the distribution of the electrolyte can be made uniform and the conductive network can be formed uniformly.

  As described above, according to the present invention, since the conductive network in the positive electrode of the cylindrical alkaline storage battery whose diameter has become extremely large due to the increase in capacity can be made uniform, the cylindrical type has a high utilization rate and a long life. An alkaline storage battery can be provided.

  Below, each claim of the present invention will be described in detail.

  The invention according to claim 1 is a first step of forming an electrode group with a positive and negative electrode and a separator for a cylindrical alkaline storage battery comprising a positive electrode containing nickel hydroxide and metallic cobalt and a negative electrode, and an electrode group And a second step of forming a battery body by storing the electrolytic solution in a battery case, and a third step of initial charging while rotating the battery body.

  By rotating the battery body during initial charging, the electrolyte distribution becomes uniform, and a conductive network formed by cobalt oxyhydroxide in the positive electrode can be formed uniformly, thus increasing the utilization rate of nickel hydroxide. Can do. Cobalt metal dissolves in the alkaline electrolyte as cobalt complex ions, and is oxidized during initial charging to become highly conductive cobalt oxyhydroxide, which is deposited in the vicinity of nickel hydroxide. Here, cobalt hydroxide or cobalt oxide may be used in combination with metallic cobalt as the conductive agent. However, metallic cobalt can perform a dissolution and precipitation reaction more reliably than cobalt hydroxide or cobalt oxide. It is an essential element to form a network. By providing the positive electrode with a strong conductive network as in the present invention, it is possible to suppress a decrease in capacity due to repeated charge and discharge.

  The device for rotating the battery body in the third step will be described in detail later, but the rotation speed is preferably 5 to 30 rpm. If it is less than 5 rpm, it is difficult to obtain the effect of the present invention. If it exceeds 30 rpm, contact failure due to excessive rotation tends to occur, and it is difficult to stably perform initial charging.

  The invention according to claim 2 is characterized in that the amount of the electrolyte solution in the second step is 1.7 to 2.5 ml / Ah or more with respect to the theoretical capacity of the positive electrode on the premise of the description in claim 1. And Conventionally, in a cylindrical alkaline storage battery, it has been regarded as a problem to uniformly spread an electrolytic solution made of a highly viscous aqueous alkali solution to an electrode group. In the present invention, by rotating the battery body during initial charging, the distribution of the electrolyte is surely uniform, so that a large amount of electrolyte can be added, which is impossible in the past, and the life characteristics can be improved. Become. However, when the amount of the electrolyte is excessive, the space volume in the battery body is reduced, and there is a problem that the internal pressure is likely to increase when gas is generated in the battery body. By using the conditions of claim 2, it is possible to maintain a high balance between the life characteristics and the internal pressure characteristics. Here, the theoretical capacity of the positive electrode can be obtained by α × 289 when the weight of nickel hydroxide (active material) in the positive electrode is α (g).

The invention described in claim 3 has a positive electrode theoretical capacity of 50 Ah on the premise of the description in claim 1.
The initial charge current in the third step is 25 to 100 hours until reaching 20% of the positive electrode theoretical capacity. The production method of the present invention is useful for all cylindrical alkaline storage batteries. Particularly, when the battery capacity is 50 Ah or more, the diameter is 40 mm or more depending on the size of the cylinder, and the electrolytic solution is used unless the production method of the present invention is used. The distribution cannot be improved and the conductive network in the positive electrode cannot be formed uniformly. In such a large battery, since it takes time to make the electrolyte distribution uniform, it is preferable to set the initial charging current to a rate of 25 to 100 hours until it reaches 20% of the positive electrode theoretical capacity. If the initial charging current is less than 25 hours, the initial charging is completed before the electrolyte solution distribution becomes uniform, so the conductive network in the positive electrode becomes non-uniform, and if it exceeds 100 hours, the productivity is excessive. descend. By making it the condition of Claim 3, the conductive network in the positive electrode in a large sized battery can be formed uniformly within a suitable time. The reason why the regulation of the initial charging current is set to 20% of the theoretical capacity of the positive electrode is that the precipitation reaction of cobalt oxyhydroxide is sufficiently performed in this region, and then the current value is increased. However, the utilization rate of nickel hydroxide does not decrease.

  The invention described in claim 4 is characterized in that, based on the description in claim 1, the amount of metallic cobalt added is 3 to 10 parts by weight with respect to 100 parts by weight of nickel hydroxide. If the addition amount of metallic cobalt as a conductive agent is less than 3 parts by weight with respect to 100 parts by weight of nickel hydroxide, a sufficient conductive network cannot be formed in the positive electrode, and the positive electrode utilization rate decreases and 10 parts by weight. Exceeding not only causes a reduction in the amount of active material (battery capacity), but also causes the possibility that excessive cobalt complex ions dissolved in the alkaline electrolyte precipitate on the negative electrode side and cause a chemical minute short circuit. By satisfying the conditions of claim 4, it is possible to provide an alkaline storage battery having both sufficient battery capacity and positive electrode utilization rate.

  Main components of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view of an alkaline storage battery of the present invention. An electrode group wound in a spiral shape between the negative electrode 1 and the positive electrode 2 via a separator 3 was inserted into a case 4 serving also as a negative electrode terminal, and after injecting an alkaline electrolyte, a safety valve 5 and a terminal portion 6 were provided. Sealing is performed by a sealing plate 7. Reference numeral 8 denotes a gasket, and 9 denotes a positive electrode current collector that electrically connects the positive electrode 2 and the sealing plate 7.

  In the case of Ni / MH, the negative electrode 1 uses a hydrogen storage alloy as an active material, a conductive agent such as carbon black, and a thickener such as carboxymethylcellulose (hereinafter abbreviated as CMC) as necessary, styrene -It is produced by adding an appropriate amount of a binder such as a butadiene copolymer (hereinafter abbreviated as SBR) to make a paste, and applying this to a core material made of a two-dimensional porous material such as a punching metal. In the case of a nickel-cadmium battery, it is produced by applying a negative electrode mixture paste mainly composed of a cadmium compound to a core material made of a two-dimensional porous material such as a punching metal.

  The positive electrode 2 uses nickel hydroxide as an active material, and includes a conductive agent such as cobalt hydroxide and metal cobalt powder, a rare earth compound such as ytterbium oxide powder, a thickener such as CMC, and polytetrafluoroethylene. An appropriate amount of a binder is added to form a paste, which is applied or filled into a core material such as a foamed nickel three-dimensional porous body, and then dried, rolled and cut.

  The separator 3 can be a nonwoven fabric made of polyolefin such as polypropylene. In addition, it is preferable that this nonwoven fabric is sulfonated etc. in order to improve affinity with electrolyte solution.

As the electrolytic solution, an aqueous solution in which KOH, NaOH, and LiOH are appropriately mixed and dissolved can be used.

  FIG. 2 is a schematic view showing an example of an apparatus for rotating a battery body in the manufacturing method of the present invention. The cylindrical alkaline storage battery 11 is placed on two cylindrical rotating bodies 12 and rotated in the direction of the arrow, thereby uniformly distributing the injected electrolyte. On the other hand, the cylindrical alkaline storage battery 11 is sandwiched between two pairs of protrusions 14 (one not shown) protruding from the support 13, and current is supplied from the cord 15 to perform initial charging.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1
Conductive positive electrode mixture paste prepared by mixing 5 parts by weight of metallic cobalt powder, 4 parts by weight of ytterbium oxide powder, and 2.5 parts by weight of zinc oxide powder with respect to 100 parts by weight of nickel hydroxide powder The support was filled, dried, pressed to a predetermined thickness, cut to a predetermined size so that the theoretical capacity was 52 Ah, and a nickel positive electrode was produced. A sulfonated polypropylene separator intervened between this positive electrode and a negative electrode having a theoretical capacity of 80 Ah using a hydrogen storage alloy was spirally wound to produce an electrode group, and this electrode group was inserted into a case also serving as a negative electrode terminal. Thereafter, an alkaline electrolyte composed of potassium hydroxide, sodium hydroxide and lithium hydroxide having a specific gravity of 1.27 was injected at a rate of 1.8 ml / Ah with respect to the positive electrode capacity, and Ni / MH shown in FIG. Produced.

  After storing this Ni / MH for 24 hours in an atmosphere at 25 ° C., the Ni / MH is set in the battery holder shown in FIG. 2 and rotated for 30 hours in an atmosphere at 25 ° C. while rotating at a rotation speed of 15 rpm in the direction of the arrow in the figure. The initial charge was performed with the amount of electricity of 20% of the positive electrode theoretical capacity at a current value of rate. Thereafter, an amount of electricity of 130% with respect to the theoretical capacity of the positive electrode was charged at a current value of 2 hours and discharged until reaching 1.0 V at a current value of 5 hours at 25 ° C. in an atmosphere. This Ni / MH is used as the battery of Example 1.

(Examples 2 to 5)
In contrast to Example 1, the Ni / MH produced in the same manner as in Example 1 except that the injection amount of the alkaline electrolyte was 1.4, 1.7, 2.5 and 2.8 ml / Ah. The battery is 2-5.

(Examples 6 to 10)
For Example 1, Ni / MH produced in the same manner as in Example 1 except that the charging current value up to 20% of the positive electrode theoretical capacity was set to 20, 25, 70, 100, and 120 hour rate. The batteries of Examples 6 to 10 are used.

(Example 11)
The battery of Example 11 is made of Ni / MH manufactured in the same manner as in Example 1 except that the charging current value after 20% with respect to the positive electrode theoretical capacity is set to a 30-hour rate with respect to Example 1.

(Examples 12 to 13)
For Example 1, the dimensions and amounts of the positive and negative electrodes, the separator, the electrolyte, and the case are adjusted so that the theoretical capacity of the positive electrode is 40 and 70 Ah, and the charging current value up to 20% of the theoretical capacity of the positive electrode is 20 Except for the time rate, Ni / MH produced in the same manner as in Example 1 was used as the batteries of Examples 12-13.

(Examples 14 to 17)
In contrast to Example 1, Ni / MH produced in the same manner as in Example 1 except that the amount of metallic cobalt powder added was 2, 3, 10 and 12 parts by weight relative to 100 parts by weight of nickel hydroxide powder. The batteries are 14-17.

(Examples 18 to 21)
The batteries of Examples 18 to 21 are made of Ni / MH manufactured in the same manner as in Example 1 except that the number of rotations at the time of initial charging was set to 3, 5, 30, and 35 rpm.

(Comparative example)
Compared to Example 1, Ni / MH produced in the same manner as in Example 1 except that initial charging is performed without rotating the battery body is used as a comparative battery.

  The following evaluation was performed using each battery described above.

(Utilization measurement)
The charge / discharge shown below was performed in an atmosphere at 25 ° C., and the value obtained by dividing the obtained discharge capacity by the positive electrode theoretical capacity was shown in Table 1 as the utilization factor.
Charging: 16 hours at 10 hour rate, standing: 1 hour, discharging: 1.0 hour at 5 hour rate.

(Intermittent charging test)
After charging for 10 hours at a rate of 10 hours in a 25 ° C. atmosphere, the following pause and supplementary charging were repeated. Each month, the battery was discharged at a 5-hour rate until it reached 1.0 V, and its capacity was measured. The intermittent charge test was repeated until the discharge capacity ratio at the time of measuring the utilization rate was less than 80%, and this period is shown in Table 1 as the lifetime.
Rest: left in a 65 ° C. atmosphere for 24 hours, supplementary charge: 2 hours at a 10 hour rate in a 65 ° C. atmosphere.

In the case of Ni / MH having a capacity of 50 Ah or more, it is clear from the comparative example that the utilization rate and the lifetime are reduced unless rotating at the initial charge. This is because the battery is large and the electrolyte distribution is non-uniform, and the cobalt oxyhydroxide generated during initial charging is locally deposited in the positive electrode, so the conductive network of the positive electrode is not uniform and the characteristics deteriorate. it is conceivable that.

  On the other hand, each example of the present invention in which the initial charge / discharge was performed while rotating was able to make the liquid distribution in the battery body more uniform, resulting in a conductive network formed by cobalt oxyhydroxide in the positive electrode. It became uniform, the utilization rate of nickel hydroxide increased, and the capacity reduction due to repeated charge and discharge was also suppressed. However, in Example 2 in which the injection amount of the electrolyte was small, the utilization rate of nickel hydroxide was increased, but the lifetime was slightly shortened because the separator was exhausted early due to corrosion of the hydrogen storage alloy. Further, in Example 5 in which the injection amount of the electrolytic solution was large, the space volume in the battery body decreased, and the internal pressure increased during the initial charge, so that the valve of the sealing plate was operated. As a result, part of the electrolyte flowed out and the lifetime was slightly shortened.

  In Example 6 having a high initial charging current value, the formation of a conductive network by cobalt oxyhydroxide was insufficient, and the utilization rate was slightly reduced. Further, Example 10 having a low initial charge current value is not preferable because the utilization factor and lifetime are good, but it takes time for the initial charge. Here, in Example 11 in which the current value is not changed after 20% with respect to the theoretical capacity of the positive electrode during initial charging, the characteristics are improved as compared with Example 1 in which the current value after 20% is increased to increase the speed. Therefore, from the viewpoint of productivity, it is preferable to increase the current value after 20% during initial charging to increase the speed.

  When the current value of the initial charge was relatively high, Example 13 with a large theoretical capacity had a relatively low decrease in utilization rate compared to Example 12 with a small positive electrode theoretical capacity. From this, it can be seen that the effect of reducing the current value of the initial charge is significant in a battery having a large capacity of 50 Ah or more.

  In Example 14, where the metal cobalt was low in the positive electrode, the formation of the conductive network was slightly insufficient even with the production method of the present invention, and the utilization rate was slightly reduced. Further, in Example 17 with a large amount of metallic cobalt, a chemical minute short circuit occurred during the intermittent charge storage test, and the life characteristics slightly decreased.

  In Example 18 in which the rotation speed of the battery body at the time of initial charge / discharge was slow, the liquid distribution inside the battery body was not uniform, and the utilization rate was slightly reduced. Moreover, in Example 21 with a high rotation speed, fine disconnection occurred continuously at the time of initial charge, so that the conductive network was insufficient and the utilization rate was slightly reduced. As described above, by rotating the battery body during initial charging as in the present invention, the utilization factor of the positive electrode and the life characteristics of the battery can be improved. At this time, until the number of revolutions of the battery body is 5 to 30 rpm, the amount of metallic cobalt added to the positive electrode is 3 to 10 parts by weight with respect to 100 parts by weight of nickel hydroxide, and the initial charging current reaches 20% of the theoretical capacity of the positive electrode It can be seen that the effect of the present invention is further enhanced when the rate is 25 to 100 hours, the amount of the electrolyte is 1.7 to 2.5 ml / Ah with respect to the theoretical capacity of the positive electrode, and the theoretical capacity of the positive electrode is 50 Ah.

  The manufacturing method according to the present invention can increase the capacity by increasing the effect of addition of metallic cobalt used for the positive electrode for alkaline storage batteries, and can extend the life by making the electrolyte distribution uniform, especially for large batteries. The applicability is high as the power source of the equipment used, and the effect is great.

Schematic diagram showing the structure of a nickel metal hydride battery according to the present invention. The figure which shows an example of the holder which sets a battery at the time of initial charge

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Negative electrode 2 Positive electrode 3 Separator 4 Case 5 Safety valve 6 Terminal part 7 Sealing plate 8 Gasket 9 Positive electrode collector 11 Cylindrical alkaline storage battery 12 Rotating body 13 Support body 14 Protrusion part 15 Code

Claims (4)

A method for producing a cylindrical alkaline storage battery comprising a positive electrode comprising nickel hydroxide and metallic cobalt and a negative electrode,
A first step of forming an electrode group with the positive electrode, the negative electrode, and a separator;
A second step of constructing a battery body by storing the electrode group and the electrolytic solution in a battery case;
A method for manufacturing a cylindrical alkaline storage battery, comprising a third step of initial charging while rotating the battery body. The method for producing a cylindrical alkaline storage battery according to claim 1, wherein the amount of the electrolytic solution in the second step is 1.7 to 2.5 ml / Ah with respect to the theoretical capacity of the positive electrode. The theoretical capacity of the positive electrode is 50 Ah or more,
2. The method for manufacturing a cylindrical alkaline storage battery according to claim 1, wherein the initial charging current in the third step is set to a rate of 25 to 100 hours until it reaches 20% of the theoretical capacity of the positive electrode. 2. The method for producing a cylindrical alkaline storage battery according to claim 1, wherein the addition amount of the metallic cobalt is 3 to 10 parts by weight with respect to 100 parts by weight of the nickel hydroxide.