JP2010165695A - Method of manufacturing electrode mixture paste for alkaline storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an efficient method of manufacturing an electrode mixture paste for an alkaline storage battery capable of improving diffusion property of each kind of additive agents which are added to an electrode for improving battery characteristics while using a stable polysaccharide under an environment where the battery is used. <P>SOLUTION: Two kinds of powders of different average particle sizes and polysaccharide are preconditioned to be included, and larger powder A has the average particle size of 8-35 μm and smaller powder B has the average particle size of 0.1-5 μm. The manufacturing method is composed of a first process in which the powder B and the saccharide are kneaded and a second process in which the kneaded product in the first process and the powder A are kneaded. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing an electrode mixture paste for an alkaline storage battery, and more particularly to a technique for improving the dispersibility of an electrode mixture indispensable for improving the characteristics of an alkaline storage battery.

  In recent years, with the widespread use of information equipment, development of high energy density alkaline storage batteries has been demanded. In response to this demand, in the field of nickel cadmium storage batteries (hereinafter referred to as NiCad batteries), the capacity of NiCad batteries using conventional sintered nickel positive electrodes has increased, and the capacity has increased by 30 to 60%. A high energy density nickel-cadmium battery using a metal foam nickel positive electrode has been developed. Furthermore, a nickel-metal hydride storage battery (hereinafter referred to as Ni / MH) having a higher capacity than a nickel-cadmium battery using a hydrogen storage alloy for the negative electrode has been developed.

  In particular, for Ni / MH, in order to improve the energy density of the positive electrode, an active material such as nickel hydroxide or a hydrogen storage alloy is added to a highly porous three-dimensional metal porous body such as a foamed nickel porous body or a nickel fiber porous body. The electrode mixture containing is filled and rolled at high density. Various additives are added to these positive electrode and negative electrode for the purpose of improving various characteristics such as improvement of utilization rate and improvement of high temperature characteristics. In general, since the additive has an average particle size smaller than that of the active material, various methods for producing electrode mixture pastes for efficient dispersion have been proposed.

  Specifically, in the kneading, the rotational speed of stirring is changed to improve the dispersibility of the additive to increase the utilization (for example, Patent Document 1), and an alkali solution is added to the mixture of the active material and the additive And a method of improving the dispersibility by mixing the active material and the additive and kneading in a kneaded state (for example, Patent Document 3) has been proposed. ing.

Japanese Patent Application Laid-Open No. 06-036767 Japanese Patent Laid-Open No. 10-106552 JP 2001-167756 A

  Alkaline storage batteries such as nickel-cadmium batteries and Ni / MH use polysaccharides with high alkali resistance and high electrochemical stability as thickeners to increase dispersibility and give the paste an appropriate viscosity. When a plurality of powders having different average particle diameters are kneaded with this polysaccharide, there is a problem that even if the methods of Patent Documents 1 to 3 are used, the dispersion becomes non-uniform and the utilization rate decreases.

  The present invention solves the above-mentioned problems, and is an efficient alkali that can improve the dispersibility of various additives added to an electrode for improving battery characteristics while using a polysaccharide that is stable in a battery use environment. It aims at providing the manufacturing method of the electrode mixture paste for storage batteries.

In order to solve the above-mentioned problems, the method for producing an electrode mixture paste for an alkaline storage battery according to the present invention is based on the premise that two kinds of powders and polysaccharides having different average particle diameters are included, and the average particles of a large powder A The first step of kneading powder B and polysaccharide, and the kneaded product and powder A of the first step, having a diameter of 8 to 35 μm and an average particle size of small powder B of 0.1 to 5 μm And a second step of kneading.

  Since polysaccharides have a chain structure consisting of repeating units mainly composed of saturated 6-membered rings, the thickening effect is high, but the steric hindrance is large because the 6-membered rings are saturated bonds. Is inflexible (hard to bend). Therefore, when an active material that is a large powder, an additive that is a small powder, and a polysaccharide are added simultaneously and kneaded, the non-flexible polysaccharide is selectively adsorbed only to the active material having a gentle spherical surface. . Therefore, an additive that is hardly adsorbed by the polysaccharide serving also as a dispersant aggregates in the electrode mixture paste, and the dispersibility is lowered. However, in the production method of the present invention, since the additive that is not easily adsorbed by the polysaccharide is first kneaded with the polysaccharide, the dispersion state of the additive in the electrode mixture paste is improved, so that the battery characteristics are improved.

  In the above description, the effect of the present invention has been described by taking the active material as the powder A and the additive as the powder B. However, in order to improve the filling property, two kinds of active materials having the same composition but different in average particle diameter are used. Even when used, the same effect can be obtained.

  As described above, according to the present invention, the dispersibility of two kinds of powders having different average particle diameters can be improved, and therefore, if the powder having a small particle diameter is an additive, the effect is drastically improved. It is possible to provide an alkaline storage battery having excellent battery characteristics such as life characteristics.

The flowchart of the manufacturing method of the electrode mixture paste for alkaline storage batteries of this invention The flowchart of the manufacturing method of the conventional electrode mixture paste for alkaline storage batteries

  Below, the manufacturing method of the electrode mixture paste for alkaline storage batteries of this invention is demonstrated in detail.

  The invention according to claim 1 is a method for producing an electrode mixture paste for an alkaline storage battery on the assumption that two kinds of powders and polysaccharides having different average particle diameters are included, and the average particle diameter of a large powder A 8 to 35 μm, the average particle size of the small powder B is 0.1 to 5 μm, and the first step of kneading the powder B and the polysaccharide, and the kneaded product and the powder A of the first step are kneaded And a second step. As described above, polysaccharides have a high thickening effect, but the chain structure is not flexible and is not easily bent. Here, if the above-mentioned materials are kneaded together, the polysaccharide is selectively adsorbed only on the larger powder A, and the powder B is agglomerated in the electrode mixture paste with hardly being adsorbed on the polysaccharide that also serves as a dispersant. To do. As described in the first aspect, the powder B which is difficult to be adsorbed by the polysaccharide is first kneaded with the polysaccharide, thereby improving the battery characteristics as well as the dispersibility in the electrode mixture paste.

  Here, it is preferable that the powder A is an active material and the powder B is an additive because the effect of the additive (conductivity, high-temperature charging efficiency, etc.) is improved. Further, it is preferable that both powders A and B are active materials because the application / filling efficiency (g / ml) of the electrode mixture paste is improved and a high capacity can be achieved without difficulty.

  The powder A needs to have an average particle size of 8 to 35 μm. If it is less than 8 μm, the adsorptivity of the polysaccharide is reduced, which is not preferable, and if it exceeds 35 μm, the application / filling efficiency of the electrode mixture paste is significantly reduced, which is not preferable. Further, the powder B needs to have an average particle size of 0.1 to 5 μm. If it is less than 0.1 μm, even if it has the production method of the present invention, the adsorptivity of the polysaccharide is lowered. This is not preferable.

  The invention according to claim 2 includes a particulate binder in addition to powder A / powder B and polysaccharide, and in addition to the first and second steps described above, kneading in the second step. It has the 3rd process of knead | mixing a thing and a binder. Examples of the particulate binder include styrene-butadiene copolymer rubber (hereinafter referred to as SBR) and modified products thereof, polytetrafluoroethylene (hereinafter referred to as PTFE), and modified rubber containing an acrylonitrile unit. These binders have a functional group containing an oxygen atom on their surface or a surfactant adsorbed on the surface. Since this functional group has high affinity with the hydroxyl group and ether moiety present in the polysaccharide, when using the above-mentioned binder from the viewpoint of increasing the adhesion of the electrode mixture paste, chemical affinity with the polysaccharide It is preferable to knead the powders A and B, which are not so high, and the polysaccharide first, and then add and knead the binder.

The invention described in claim 3 is characterized in that the powder A is nickel hydroxide and the powder B is at least one of cobalt, a cobalt compound and a rare earth element compound. This composition is related to the positive electrode of alkaline storage battery. Cobalt and cobalt compounds are added to provide a conductive network to non-conductive nickel hydroxide (positive electrode active material), and rare earth element compounds are mainly charged at high temperature. It is added to improve efficiency. The battery characteristics of the alkaline storage battery can be improved by producing the positive electrode mixture paste made of the above-described material by the production method of the present invention. Examples of cobalt compounds include CoO, Co (OH) ₂ and CoOOH, and examples of rare earth element compounds include Y ₂ O ₃ , Yb ₂ O ₃ , Lu ₂ O ₃ , Tm ₂ O ₃ and Er. ₂ O ₃ can be mentioned.

  The invention described in claim 4 is characterized in that, in addition to the requirement of claim 3, the polysaccharide is xanthan gum. Xanthan gum is composed of a main chain portion due to glucose binding and a side chain portion composed of mannose and the like, and has a thickening effect larger than that of carboxymethyl cellulose (hereinafter referred to as CMC) which is a general polysaccharide and only the main chain portion. Therefore, sedimentation of additives having a large specific gravity such as cobalt, cobalt compounds, and rare earth element compounds can be suppressed.

  The invention according to claim 5 is characterized in that the powder A is a hydrogen storage alloy and the powder B is a rare earth element compound. This composition relates to a negative electrode of Ni / MH, and the rare earth element compound is added to improve high-temperature charging efficiency and corrosion resistance against an alkaline electrolyte. By producing a negative electrode mixture paste made of the above-described material by the production method of the present invention, various battery characteristics of Ni / MH can be improved. An example of the rare earth element compound is the same as that of the third aspect. Further, it is one of preferred embodiments to add a carbonaceous material (for example, hard carbon such as ketjen black and carbon black) in order to enhance conductivity. Although the secondary particle diameter of the carbonaceous material varies depending on the agglomerated state, the affinity for the dispersion medium (water, polar solvent, etc.) is low in surface properties, so that the carbonaceous material is kneaded together with the powder B in the first step. preferable.

  The invention described in claim 6 is characterized in that, in addition to the requirements of claim 5, the polysaccharide is CMC and a modified product thereof. As described above, the thickening effect is higher in the polysaccharide having a side chain portion such as xanthan gum. However, when the powder A is a hydrogen storage alloy, it is preferable to select CMC and a modified product thereof as the polysaccharide. This is presumably because the hydrogen storage alloy has a crushed stone shape and is not spherical like nickel hydroxide, so that a polysaccharide having a relatively flexible structure is more easily adsorbed. In addition, as a modified body of CMC, what made the etherified part into sodium salt and ammonium salt is mentioned.

In addition to the above-described configuration (active material + additive), when two types of nickel hydroxide having different average particle diameters are used as powders A and B, the application / filling efficiency (g / ml) of the electrode mixture paste is The capacity can be increased without difficulty. In this case, it is more preferable to coat the surface of nickel hydroxide with a cobalt-cobalt compound and a rare earth element compound because the effect of claim 3 can be imparted in addition to the improvement of coating / filling efficiency.

  FIG. 1 is a flowchart showing a method for producing an electrode mixture paste for an alkaline storage battery of the present invention. As a first step, the smaller powder B, an appropriate amount of polysaccharide and a dispersion medium (water, polar solvent, etc.) are kneaded in advance. Subsequently, as the second step, the larger powder A is added to the kneaded product of the first step, and an appropriate amount of a dispersion medium is added and kneaded as necessary. Here, from the viewpoint of increasing the adhesion of the electrode mixture paste, when the particulate binder is used, the binder described above is added to the kneaded product of the second step as the third step.

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

(Example 1-1)
According to FIG. 1, metallic cobalt powder, CoOOH powder, Yb ₂ O ₃ powder (all average particle diameter 4 μm) and xanthan gum powder were kneaded together with an appropriate amount of pure water to prepare a positive electrode additive paste. To this paste, nickel hydroxide powder having an average particle size of 10 μm is added and kneaded and stirred, and further a dispersion of PTFE binder (D-1 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is added to prepare a positive electrode mixture paste. Produced. Here, 5 parts by weight of metallic cobalt, 5 parts by weight of CoOOH, 4 parts by weight of Yb ₂ O ₃ , 0.15 parts by weight of xanthan gum, and 0.1 parts by weight of PTFE with respect to 100 parts by weight of nickel hydroxide. (Solid content ratio). The positive electrode mixture paste thus prepared is filled into a foamed nickel porous body as an electrode support, dried and pressed to be cut into predetermined dimensions (width 35 mm, length 220 mm, thickness 0.6 mm). A positive electrode having a theoretical capacity of 2800 mAh was produced.

On the other hand, according to FIG. 1, Y ₂ O ₃ powder (average particle size 4 μm), Ketjen black powder and CMC (Daiichi Kogyo Seiyaku EP / trade name) as carbonaceous materials were kneaded together with an appropriate amount of pure water, and the negative electrode An additive paste was prepared. Hydrogen paste alloy powder (average particle size 27 μm) that has been subjected to hot alkali immersion treatment was added to this paste, and kneaded and stirred. Further, SBR dispersion (NSK-72 / trade name, manufactured by Nippon A & L Co., Ltd.) was added to the negative electrode. A mixture paste was prepared. Here, with respect to 100 parts by weight of the hydrogen storage alloy, Y ₂ O ₃ is 0.7 parts by weight, Ketjen Black is 0.3 parts by weight, and CMC is 0.15 parts by weight (solid content ratio). The negative electrode mixture paste thus prepared was applied to a punching metal that is a two-dimensional porous body, dried, pressed and then cut into predetermined dimensions (width 35 mm, length 310 mm, thickness 0.30 mm) to 4200 mAh. A negative electrode having a theoretical capacity was prepared.

  Cylindrical sealed NI / MH was produced using the above positive and negative electrodes. Potassium hydroxide-sodium hydroxide-lithium hydroxide having a specific gravity of 1.27 is inserted into a case also serving as a negative electrode terminal, in which a positive and negative electrode and a separator made of sulfonated polypropylene that separates them are spirally swung. After injecting 4.7 ml of the alkaline electrolyte consisting of, a sealing plate provided with a safety valve and a terminal part was arranged and sealed. The battery thus produced is referred to as the battery of Example 1-1.

(Examples 1-2 to 3)
Ni / MH produced in the same manner as in Example 1-1, except that the average particle diameter of nickel hydroxide was set to 15 and 8 μm with respect to Example 1-1. Use batteries.

(Examples 1-4 to 6)
For Example 1-1, it was produced in the same manner as Example 1-1 except that the average particle diameters of the metal cobalt powder, CoOOH powder and Yb ₂ O ₃ powder were all 5, 2 and 0.1 μm. Let Ni / MH be the batteries of Examples 1-4, 1-5, and 1-6.

(Examples 1-7 to 8)
Ni / MH produced in the same manner as in Example 1-1, except that the average particle size of the hydrogen storage alloy powder was changed to 20 and 35 μm with respect to Example 1-1, Examples 1-7 and 1-8 were used. Battery.

(Examples 1-9 to 11)
Ni / MH produced in the same manner as in Example 1-1, except that the average particle diameter of Y ₂ O ₃ powder was set to 5, 2 and 0.1 μm with respect to Example 1-1. The batteries are 9, 1-10, and 1-11.

(Comparative Example 1-1)
In accordance with FIG. 2, which is a conventional batch kneading method, a metal cobalt powder, a CoOOH powder, a Yb ₂ O ₃ powder (all with an average particle diameter of 4 μm), a zinc oxide powder, a xanthan gum powder, and a nickel hydroxide powder with an average particle diameter of 10 μm. A battery of Comparative Example 1-1 is made of Ni / MH produced in the same manner as in Example 1-1 except that a positive electrode mixture paste was produced by kneading together with an appropriate amount of pure water.

(Comparative Example 1-2)
A suitable amount of Y ₂ O ₃ powder, ketjen black powder (both with an average particle diameter of 4 μm) and hydrogen storage alloy powder (average particle diameter of 27 μm) that has undergone CMC and hot alkali immersion treatment in accordance with the conventional batch kneading method shown in FIG. A battery of Comparative Example 1-2 is made of Ni / MH produced in the same manner as in Example 1-1 except that a negative electrode mixture paste is produced by kneading together with pure water.

(Comparative Example 1-3)
A battery of Comparative Example 1-3 is made of Ni / MH produced in the same manner as in Example 1-1 except that the average particle diameter of nickel hydroxide is set to 7 μm with respect to Example 1-1.

(Comparative Examples 1-4-5)
Ni / produced in the same manner as in Example 1-1, except that the average particle sizes of the metallic cobalt powder, CoOOH powder, and Yb ₂ O ₃ powder were all 6 and 0.05 μm. Let MH be the batteries of Comparative Examples 1-4 and 1-5.

(Comparative Example 1-6)
A battery of Comparative Example 1-4 is made of Ni / MH manufactured in the same manner as in Example 1-1 except that the average particle size of the hydrogen storage alloy powder is 40 μm with respect to Example 1-1.

(Comparative Examples 1-7 to 8)
Ni / MH produced in the same manner as in Example 1-1, except that the average particle diameter of Y ₂ O ₃ powder was changed to 7 and 0.05 μm with respect to Example 1-1, and Comparative Example 1-7 and The battery is 1-8.

After each of the above batteries was left for 24 hours, the following initial charge / discharge was performed in an atmosphere at 25 ° C., and then various evaluations were performed. The results are shown in (Table 1).
Initial charge / discharge conditions:
Charging-15 hours at 280 mA (1 hour after charging).
Discharge-Until reaching 1.0V at 900mA.

(Normal temperature charge / discharge test)
The following charge / discharge was performed in a 25 ° C. atmosphere. The results are shown in (Table 1).
Charging / discharging conditions:
Charging at 280 mA for 16 hours (1 hour after charging).
Discharge-Until reaching 1.0V at 560mA.

(High temperature charge test)
The following charge / discharge was performed. The results are shown in (Table 1).
Charging / discharging conditions:
Charging-15 hours at 280 mA in an atmosphere at -50 ° C (left for 3 hours in an atmosphere at 25 ° C after charging).
Discharge -25 ° C until reaching 1.0V at 900mA.

(Intermittent charge storage test)
After charging at 280 mA for 10 hours in a 25 ° C. atmosphere, the following pause-auxiliary charging cycle was repeated in a 65 ° C. atmosphere.
Rest-Leave for 22 hours, supplementary charge-2 hours at 280 mA.

  Each time the pause-auxiliary charge cycle was repeated for one month, the discharge capacity was measured under the same conditions as in the room temperature charge / discharge test described above. Then, the storage test consisting of the pause-complementary charge cycle and the discharge capacity measurement was repeated until the ratio of the discharge capacity after storage to the discharge capacity before storage (hereinafter referred to as capacity recovery rate) was less than 80%. The number of months in which this preservation test was repeated is shown in (Table 1).

By producing the positive electrode mixture paste by the kneading method of the present invention (FIG. 1) regardless of the conventional batch kneading method (Comparative Example 1-1 / FIG. 2), metallic cobalt hitting the powder B, CoOOH and Yb ₂ O ₃ can be efficiently dispersed. As a result, room temperature charge / discharge characteristics were improved as an effect of enhancing the conductive network, and high temperature charge characteristics were improved as an effect of Yb ₂ O ₃ . However, when the average particle diameter of nickel hydroxide is too small (Comparative Example 1-3), the dispersion efficiency of Yb ₂ O ₃ mainly decreases because the xanthan gum which is a polysaccharide is difficult to adsorb on the nickel hydroxide itself. As a result, the high temperature charge characteristics deteriorated. Moreover, when the average particle diameter of powder B which is an additive is too large (Comparative Example 1-4), the function as an additive falls remarkably, and when the average particle diameter is too small (Comparative Example 1-5), this Even if it had the manufacturing method of invention, the adsorptivity of polysaccharide fell, and it resulted in the normal temperature charging / discharging characteristic and high temperature charging characteristic falling.

By producing the negative electrode mixture paste by the kneading method of the present invention (FIG. 1) regardless of the conventional batch kneading method (Comparative Example 1-2 / FIG. 2), Y ₂ O ₃ corresponding to the powder B is efficiently dispersed. can do. As a result, the intermittent charge storage characteristics were improved by improving the corrosion resistance against the alkaline electrolyte. However, when the average particle size of the hydrogen storage alloy was too large (Comparative Example 1-6), the intermittent charge storage characteristics were at a low level as a result of a significant decrease in the application / filling efficiency of the electrode mixture paste. In the case the average particle size of an additive Y ₂ O ₃ is too large if (Comparative Example 1-7) functions as an additive is significantly reduced, the average particle size is too small (Comparative Example 1-8) Even with the production method of the present invention, the polysaccharide adsorptivity decreased, and the intermittent charge storage characteristics were both low.

  As described above, as a result of using an additive as the powder B, when preparing an electrode mixture paste for an alkaline storage battery containing two types of powders and polysaccharides having different average particle sizes, the average particle size of the large powder A is The first step of kneading powder B and polysaccharide, and the kneaded product of the first step and powder A are kneaded with an average particle size of 8 to 35 μm and small powder B being 0.1 to 5 μm. It turns out that it needs to be divided | segmented into the 2nd process.

(Example 2-1)
According to FIG. 1, after mixing nickel hydroxide having an average particle diameter of 4 μm whose surface is coated with Co (OH) ₂ as powder B and xanthan gum powder together with an appropriate amount of pure water, the surface of powder A is Co Nickel hydroxide with an average particle diameter of 10 μm coated with (OH) ₂ was added and further kneaded, and finally a dispersion of PTFE binder was added to prepare a positive electrode mixture paste. The coated cobalt hydroxide is 7 parts by weight with respect to 100 parts by weight of nickel hydroxide, nickel hydroxide (powder B) having an average particle diameter of 4 μm and nickel hydroxide (powder A) having an average particle diameter of 10 μm. The mixing ratio is 1: 1 by weight. Using this positive electrode mixture paste, a positive electrode was produced in the same manner as in Example 1-1. In addition, this positive electrode was produced so that thickness might be set to 0.6 mm similarly to Example 1-1.

  The negative electrode produced in Example 1-1 was used, and Ni / MH produced in the same manner as in Example 1-1 was used as the battery of Example 2-1.

(Examples 2-2 to 3)
Ni / MH produced in the same manner as in Example 2-1 except that the average particle diameter of powder A was set to 15 and 8 μm with respect to Example 2-1, batteries of Examples 2-2 and 2-3. And

(Examples 2-4 to 6)
Ni / MH produced in the same manner as in Example 2-1 except that the average particle size of powder B was set to 5, 2, and 0.1 μm with respect to Example 2-1, and Examples 2-4 and 2 The batteries are −5 and 2-6.

(Comparative Example 2-1)
Produced in the same manner as in Example 2-1, except that the same material as in Example 2-1 was collectively kneaded together with an appropriate amount of pure water according to FIG. Ni
/ MH is the battery of Comparative Example 2-1.

(Comparative Example 2-2)
A battery of Comparative Example 2-2 is made of Ni / MH produced in the same manner as in Example 2-1, except that the average particle diameter of the powder A is 7 μm with respect to Example 2-1.

(Comparative Examples 2-3 to 4)
Compared to Example 2-1, Ni / MH produced in the same manner as in Example 2-1 except that the average particle size of the powder B was 6 and 0.05 μm was used as Comparative Examples 2-3 and 2-4. Battery.

  Each of the above batteries was left to stand and charged / discharged in the same manner as in Example 1, and then a room temperature charge / discharge test similar to that in Example 1 was performed. The results are shown in (Table 2).

  The positive electrode mixture paste is produced by the kneading method of the present invention (FIG. 1) regardless of the conventional batch kneading method (Comparative Example 2-1 / FIG. 2), whereby the powder B is efficiently dispersed in the powder A. can do. Although the room temperature charge / discharge characteristics were improved in the results, it is considered that this was due to the increase in the amount of the positive electrode active material per unit volume because the filling efficiency was improved as compared with Example 1-1. Thus, it can be seen that even when powders having the same composition are mixed, a high capacity can be achieved without difficulty by developing the present invention.

  However, when the average particle diameter of the powder A was too small (Comparative Example 2-2), the xanthan gum, which is a polysaccharide, was difficult to adsorb on the powder A itself, so that the dispersion of the powder A was deteriorated and the filling efficiency was lowered. Further, when the average particle size of the powder B is too large (Comparative Example 2-3), the difference in the particle size between the powder A and the powder B is substantially eliminated, so that the powder B is overdispersed, and the filling efficiency is reduced. . Furthermore, when the average particle diameter of the powder B is too small (Comparative Example 2-4), even if it has the manufacturing method of this invention, since the adsorptivity of the polysaccharide to the powder B will fall, the dispersion | distribution of the powder B will deteriorate. As a result, the filling efficiency decreased. As a result, in these three comparative examples, the room temperature charge / discharge efficiency was low.

In this example, it was shown that the powder B was effective for metallic cobalt, CoOOH, Yb ₂ O ₃ and Y ₂ O ₃ , but when CoO or Co (OH) ₂ was added as a cobalt compound In addition, the effect of the present invention can be obtained even when an oxide, hydroxide, or fluoride containing at least one element of Y, Er, Tm, Yb, and Lu is added as the rare earth element compound. Not too long.

  The production method according to the present invention can be developed to increase the effect of additives used for alkaline storage battery electrodes, and to easily increase the capacity by improving the filling properties of the active material. The availability is high and the effect is great.

Claims (2)

A method for producing an electrode mixture paste for an alkaline storage battery comprising two kinds of powders having different average particle sizes and a polysaccharide,
Of the powders, the larger powder A has an average particle size of 8 to 35 μm, and the smaller powder B has an average particle size of 0.1 to 5 μm,
A first step of kneading the powder B and the polysaccharide;
In the method for producing an electrode mixture paste for an alkaline storage battery, comprising the second step of kneading the kneaded product of the first step and the powder A,
The method for producing an electrode mixture paste for an alkaline storage battery, wherein the powder A is a hydrogen storage alloy and the powder B is a rare earth element compound. The method for producing an electrode mixture paste for an alkaline storage battery according to claim 1, wherein the polysaccharide is carboxymethylcellulose and a modified product thereof.

Images