JP2007324075A - Alkaline storage battery, positive electrode for alkaline storage battery, and manufacturing method of its mix paste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress sedimentation of positive mix paste of an alkaline storage battery by increasing its viscosity without increasing the amount of a thickening agent. <P>SOLUTION: The manufacturing method of the positive mix paste for the alkaline storage battery comprises a first process using nickel hydroxide powder as an active material, water as a solvent, and carbohydrates comprising a straight chain containing a monosaccharide and a side chain containing saturated six-membered ring structure, and a cellulose derivative as the thickening agent, and kneading the nickel hydroxide powder; and a second process kneading the kneaded material in the first process and the cellulose derivative. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a positive electrode mixture paste for an alkaline storage battery, and more particularly to a technique for improving the viscosity of an electrode mixture paste for 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, as a positive electrode of a nickel cadmium storage battery (hereinafter referred to as a nickel cadmium battery) or a nickel metal hydride storage battery (hereinafter referred to as Ni / MH), the capacity is 30 to 60% higher than that of a conventional sintered nickel positive electrode. Technology has been developed that uses certain foamed metal nickel cathodes. This positive electrode is a highly porous three-dimensional metal porous body such as a foamed nickel porous body or nickel fiber porous body filled with a positive electrode mixture containing an active material such as nickel hydroxide powder and rolled at high density. .

  This positive electrode is produced by filling the three-dimensional metal porous body with the positive electrode mixture paste containing the active material described above. Various thickeners are added for the purpose of suppressing the sedimentation of the positive electrode mixture paste and achieving long-time filling. Generally, since the thickening depends on the type of thickener contained in the positive electrode mixture paste, various techniques for optimizing the composition have been proposed.

Specifically, nickel hydroxide powder, which is an active material, a method of using at least one selected from water-soluble cellulose derivatives and water-soluble polysaccharides and a water-soluble polyol (for example, Patent Document 1), and coating with cobalt oxide A method (for example, Patent Document 2) in which 0.1 to 0.5 parts by weight of a natural polysaccharide is added to 100 parts by weight of nickel hydroxide powder in the nickel hydroxide powder has been proposed.
JP 2002-184398 A JP 2003-068293 A

  However, the positive electrode mixture paste produced by the methods of Patent Documents 1 and 2 has a problem that if left as it is, the paste settles and water and the mixture composition are separated. In order to suppress the sedimentation due to the separation, the amount of the thickener must be increased. However, if the amount of the thickener is increased, the positive electrode reaction is hindered and the discharge characteristics are deteriorated.

  This invention solves said subject, and it aims at improving the viscosity of the positive mix paste of an alkaline storage battery and suppressing sedimentation, without increasing thickener itself.

  In order to solve the above-mentioned problems, a method for producing a positive electrode mixture paste for an alkaline storage battery according to the present invention comprises a linear and saturated six-membered ring structure containing monosaccharides, using nickel hydroxide powder as an active material, water as a solvent, and A first step of kneading nickel hydroxide powder using a saccharide (hereinafter abbreviated as saccharide A) and a cellulose derivative comprising a side chain, as a thickener, and a kneaded product and cellulose of the first step And a second step of kneading the derivative.

In the present invention, a carbohydrate A and a cellulose derivative are used in combination as a thickener. However, since saccharide A has a side chain containing a saturated 6-membered ring in addition to a straight chain containing a monosaccharide, it can impart sedimentation resistance to a high-density positive electrode mixture paste having a high thickening effect, It is difficult to impart fluidity. On the other hand, the cellulose derivative has a low effect of imparting fluidity to the positive electrode mixture paste, although the thickening action is lower than that of the polysaccharide having a side chain. In order to take advantage of both, it is necessary to add a cellulose derivative in the second step. The reason for this is that, as a result of intensive studies, the present inventors have introduced a cellulose derivative into the first step of kneading the nickel hydroxide powder, which is an active material. It has been found that the desired fluidity cannot be imparted to the positive electrode mixture paste. In order to reduce the shearing force, the amount of water added in the first step may be increased. However, in this method, nickel hydroxide powder or an appropriate additive (such as a cobalt compound as a conductive agent) is used as the positive electrode mixture. This is not preferable because it causes a new problem that the paste is not sufficiently dispersed. Therefore, by adding a cellulose derivative in the second step, it is possible to produce a positive electrode mixture paste having both good fluidity and dispersibility by optimizing the shearing force to be applied, so that battery characteristics such as discharge characteristics are good. A positive electrode for an alkaline storage battery can be obtained.

  As described above, according to the present invention, a positive electrode mixture paste having good sedimentation resistance, fluidity, and dispersibility can be produced by utilizing the characteristics of the two thickeners. A positive electrode for an alkaline storage battery that exhibits characteristics can be obtained stably and in large quantities.

  Below, the manufacturing method of the positive mix paste for alkaline storage batteries of this invention is demonstrated in detail using figures.

  1st invention is the manufacturing method of the positive mix paste for alkaline storage batteries which uses nickel hydroxide powder as an active material, water as a solvent, and uses saccharide A and a cellulose derivative as a thickener, It consists of the 1st process of kneading | mixing powder, and the 2nd process of kneading | mixing the kneaded material and cellulose derivative of a 1st process, It is characterized by the above-mentioned.

  Carbohydrate A has a side chain containing a saturated 6-membered ring in addition to a straight chain containing a monosaccharide, so that it has high thickening action and can impart sedimentation resistance to a high-density positive electrode mixture paste. It is difficult to impart sex. On the other hand, the cellulose derivative has a low effect of imparting fluidity to the positive electrode mixture paste, although the thickening action is lower than that of the polysaccharide having a side chain. Furthermore, since the nickel hydroxide powder is wetted by water in the initial stage of the first step, a large shearing force is generated. Therefore, when a cellulose derivative is added in this step, the straight chain of the cellulose derivative is broken and the desired fluidity is obtained. Cannot be applied to the positive electrode mixture paste. Therefore, in order to take advantage of both thickeners, it is necessary to add a cellulose derivative in the second step. By adding a cellulose derivative in the second step, a positive electrode mixture paste having both good fluidity and dispersibility can be produced by optimizing the shearing force to be applied. A positive electrode for a storage battery can be obtained.

2nd invention presupposes 1st invention, Carbohydrate A is added in a 1st process, It is characterized by the above-mentioned. FIG. 1 is a flowchart showing a method for producing a positive electrode mixture paste for an alkaline storage battery of the second invention. In the first step, the active material (nickel hydroxide powder) and carbohydrate A are kneaded with an appropriate amount of water (such as a cobalt compound as a conductive agent) and an appropriate amount of water. Subsequently, as the second step, the cellulose derivative and an appropriate amount of water are added to the kneaded product of the first step and kneaded. The feature of the second invention resides in that the dispersibility of powders such as active materials and additives is enhanced by utilizing the thickening action of carbohydrate A. When the adhesion of the positive electrode for an alkaline storage battery produced using this positive electrode mixture paste is enhanced, a particulate binder is added to the kneaded product of the second step as the third step. A dispersion such as polytetrafluoroethylene (hereinafter abbreviated as PTFE) can be selected as the particulate binder. The cellulose derivative and carbohydrate A may be dissolved in water in advance and used as an aqueous solution.

  3rd invention presupposes 1st invention, Carbohydrate A is added in a 2nd process, It is characterized by the above-mentioned. FIG. 2 is a flowchart showing a method for producing a positive electrode mixture paste for an alkaline storage battery of the third invention. As a first step, an active material (nickel hydroxide powder) is kneaded with an appropriate amount of water (such as a cobalt compound as a conductive agent) and an appropriate amount of water. As the second step, the saccharide A, the cellulose derivative and an appropriate amount of water are added to the kneaded product of the first step and kneaded. The feature of the third invention is that, by simultaneously adding and kneading saccharide A and cellulose derivative, the thickening effect of saccharide A can be maximized, so the amount added is reduced, and the discharge characteristics of the alkaline storage battery Is to improve. As in the second invention, when enhancing the adhesion of the positive electrode for an alkaline storage battery produced using this positive electrode mixture paste, as a third step, a particulate binder such as PTFE is added to the kneaded product of the second step. Add a dressing. The cellulose derivative and carbohydrate A may be dissolved in water in advance and used as an aqueous solution.

  The fourth invention is characterized in that, on the premise of the first invention, the weight ratio of the cellulose derivative and the saccharide A is 2: 1 to 1: 2. When the above ratio exceeds 2: 1 and the weight ratio of the cellulose derivative is increased, the thickening effect of the carbohydrate A is not sufficiently exhibited, and the positive electrode mixture paste is slightly settled. On the other hand, when the ratio exceeds 1: 2 and the weight ratio of the saccharide A is increased, the effect of the cellulose derivative is not sufficiently exhibited, and the fluidity of the positive electrode mixture paste is slightly lowered.

  On the premise of the first invention, the fifth invention is characterized in that the total of the cellulose derivative and the carbohydrate A is 0.05 to 0.5 parts by weight with respect to 100 parts by weight of the nickel hydroxide powder. . If the total of the cellulose derivative and the saccharide A is less than 0.05 parts by weight, the effect of the thickener described above becomes difficult to be exhibited, and the total of the cellulose derivative and the saccharide A exceeds 0.5 parts by weight. When the addition amount is excessive, the reaction resistance of the electrode is increased and the charge / discharge reaction is hindered, and in particular, the discharge characteristics are slightly deteriorated.

  The sixth invention is characterized in that, based on the first invention, the cellulose derivative is carboxymethylcellulose (hereinafter abbreviated as CMC) and a modified product thereof. CMC is particularly preferable because it has a relatively high flexibility among cellulose derivatives and thus has a large effect of imparting the fluidity of the paste when added in a small amount. In addition, as a modified body of CMC, what made the etherified part into sodium salt and ammonium salt is mentioned.

  The seventh invention is characterized in that the carbohydrate A is xanthan gum on the premise of the first invention. Xanthan gum is composed of a main chain part due to glucose bonding and a side chain part composed of mannose, etc., so that it is relatively stable in an alkaline aqueous solution (alkaline battery electrolyte) among carbohydrates A and has a large thickening effect. It is particularly preferable from the viewpoint, and even when an additive having a large specific gravity is added, the precipitation of the positive electrode mixture paste can be suppressed.

  An eighth invention relates to a positive electrode for an alkaline storage battery using the positive electrode mixture paste for an alkaline storage battery obtained by the method for producing a positive electrode mixture paste for an alkaline storage battery according to any one of the first to seventh inventions. . The positive electrode mixture paste prepared based on the flowchart shown in FIG. 1 or FIG. 2 is applied to or filled in a core material such as a foamed nickel three-dimensional porous body, and this is dried, rolled, and cut. A positive electrode for an alkaline storage battery is produced.

  Here, the additive shown in FIGS. In order to increase the conductivity of the eighth alkaline storage battery positive electrode, a conductive agent such as a cobalt compound (metal cobalt or cobalt hydroxide) can be added as a conductive agent. In order to enhance the high temperature characteristics of the eighth alkaline storage battery positive electrode, rare earth oxides such as yttrium oxide and ytterbium oxide can be added.

  The ninth invention relates to an alkaline storage battery using the alkaline storage battery positive electrode of the eighth invention. By using the positive electrode for alkaline storage battery according to the eighth aspect of the invention, which can be produced stably and in large quantities, a high output alkaline storage battery can be realized.

  The alkaline storage battery according to the ninth aspect will be described in detail below. An electrode group in which the positive electrode and the negative electrode for an alkaline storage battery according to the eighth invention are opposed to each other through a separator is inserted into a case, an alkaline electrolyte is injected, and then sealed using a sealing plate.

  As the negative electrode, in the case of Ni / MH, a hydrogen storage alloy is used as an active material. To this, a conductive agent such as carbon black, and a thickener such as CMC or a styrene-butadiene copolymer (hereinafter referred to as “CMC”). An appropriate amount of a binder such as SBR) can be added to form a paste, which can be applied to a core made of a two-dimensional porous material such as a punching metal. In the case of a nickel-cadmium battery, a cadmium compound may be used as an active material, and a paste having this as a main component applied to a core material made of a two-dimensional porous material such as a punching metal may be used.

  Moreover, the nonwoven fabric which consists of polyolefins, such as a polypropylene, can be used as a separator. The nonwoven fabric is preferably subjected to a hydrophilic treatment such as a sulfonation treatment in order to increase the affinity with the alkaline electrolyte.

When the above-described positive electrode, negative electrode, and separator for alkaline storage battery are configured in a belt shape and wound, a spiral electrode group is configured. When a plurality of alkaline storage battery positive electrodes, negative electrodes, and separators are stacked, a substantially rectangular stacked electrode group is formed.
As the alkaline electrolyte, an aqueous solution in which KOH, NaOH, and LiOH are appropriately mixed and dissolved can be used. Further, the sealing plate can be provided with a safety valve for releasing a large amount of internal gas generated in an abnormal state and either a positive electrode or a negative electrode terminal.

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

(Example 1-1)
In accordance with FIG. 1, as a first step, nickel hydroxide powder, cobalt hydroxide powder and yttrium oxide powder as additives, and xanthan gum powder as carbohydrate A are kneaded together with an appropriate amount of pure water using a planetary mixer. (Kneading time 20 minutes, rotation speed 50 rpm), a first kneaded product was produced. To this first kneaded product, a 3 wt% aqueous solution of CMC (Daiichi Kogyo Seiyaku EP: product number) as a cellulose derivative is added as a second step, and kneaded and stirred for 4 minutes at a rotational speed of 2500 rpm. A kneaded material was prepared. Further, a 35% aqueous dispersion of PTFE (D-1 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was added to this second kneaded product and stirred to prepare a positive electrode mixture paste. The specific solid content ratio is 11 parts by weight of cobalt hydroxide powder, 0.5 part by weight of yttrium oxide powder, 0.1 part by weight of CMC, and 0.2 part of xanthan gum with respect to 100 parts by weight of nickel hydroxide powder. Part by weight and PTFE were 0.1 part by weight. The weight ratio of CMC to xanthan gum was 1: 2, and the total of CMC and xanthan gum relative to 100 parts by weight of nickel hydroxide powder was 0.3 parts by weight. The water content of the positive electrode mixture paste was 30%. This is Example 1-1.

(Example 1-2)
According to FIG. 2, as a first step, nickel hydroxide powder, additive cobalt hydroxide powder and yttrium oxide powder are kneaded with a suitable amount of pure water using a planetary mixer (kneading time 20 minutes, rotation speed). 50 rpm), a first kneaded material was prepared. To this first kneaded product, the same CMC aqueous solution and xanthan gum as in Example 1-1 were added as the second step, and kneaded and stirred for 4 minutes at a rotational speed of 2500 rpm to prepare a second kneaded product. Furthermore, the same PTFE aqueous dispersion as in Example 1-1 was added to the second kneaded product and stirred to prepare a positive electrode mixture paste. The specific solid content ratio is 11 parts by weight of cobalt hydroxide powder, 0.5 part by weight of yttrium oxide powder, 0.1 part by weight of CMC and 0.1 part by weight of xanthan gum with respect to 100 parts by weight of nickel hydroxide powder. Part by weight and PTFE were 0.1 part by weight. The weight ratio of CMC to xanthan gum was 1: 1, and the total of CMC and xanthan gum relative to 100 parts by weight of nickel hydroxide powder was 0.2 parts by weight. The water content of the positive electrode mixture paste was 30%. This is Example 1-2.

(Examples 1-3 to 1-6)
With respect to Example 1-1, the solid content ratio of xanthan gum to 100 parts by weight of nickel hydroxide powder was 0.1 parts by weight (Example 1-3), 0.22 parts by weight (Example 1-4), 0.0. 05 parts by weight (Example 1-5) and 0.03 parts by weight (Example 1-6), and the weight ratio of CMC to xanthan gum was 1: 1 (Example 1-3), 1: 2.2 ( Example 1-4), 2: 1 (Example 1-5), 3.3: 1 (Example 1-6), and the total of CMC and xanthan gum with respect to 100 parts by weight of nickel hydroxide powder was 0.2. Parts by weight (Example 1-3), 0.32 parts by weight (Example 1-4), 0.15 parts by weight (Example 1-5), and 0.13 parts by weight (Example 1-6). Except for the above, a positive electrode mixture paste produced in the same manner as in Example 1-1 is referred to as Examples 1-3 to 1-6.

(Examples 1-7 to 1-8)
With respect to Example 1-1, the solid content ratio of CMC to 100 parts by weight of nickel hydroxide powder was set to 0.025 parts by weight, and the solid content ratio of xanthan gum was 0.025 parts by weight (Example 1-7). And 0.02 parts by weight (Example 1-8), and the weight ratio of CMC to xanthan gum is 1: 1 (Example 1-7) and 1.25: 1 (Example 1-8). The same as Example 1-1 except that the total amount of CMC and xanthan gum relative to 100 parts by weight of nickel powder was 0.05 parts by weight (Example 1-7) and 0.045 parts by weight (Example 1-8). The positive electrode mixture paste produced in this manner is referred to as Examples 1-7 to 1-8.

(Example 1-9)
For Example 1-7, the solid content ratio of CMC to 100 parts by weight of nickel hydroxide powder was 0.02 parts by weight, the weight ratio of CMC to xanthan gum was 1: 1.25, and nickel hydroxide powder 100 weights Example 1-9 is a positive electrode mixture paste produced in the same manner as in Example 1-7, except that the total amount of CMC and xanthan gum is 0.045 parts by weight.

(Comparative Example 1-1)
According to FIG. 3, as a first step, nickel hydroxide powder, additive cobalt hydroxide powder, yttrium oxide powder, and CMC powder were kneaded together with an appropriate amount of pure water using a planetary mixer (kneading time 20 minutes). , Rotation speed 50 rpm), a first kneaded product was produced. To the first kneaded product, xanthan gum and an appropriate amount of water were added as a second step, and kneaded and stirred at a rotational speed of 2500 rpm for 4 minutes to prepare a second kneaded product. Furthermore, the same PTFE aqueous dispersion as in Example 1-1 was added to the second kneaded product and stirred to prepare a positive electrode mixture paste. The composition of the positive electrode mixture paste was the same as that of Example 1-1. This is designated as Comparative Example 1-1.

(Comparative Example 1-2)
According to FIG. 4, a first kneaded material was prepared by the first step without adding xanthan gum (kneading time 20 minutes, rotation speed 50 rpm), and the positive electrode mixture paste that passed through the first kneaded material was utilized. Then, the same positive electrode mixture paste as that of Example 1-1 was produced. This is designated as Comparative Example 1-2.

(Comparative Example 1-3)
A positive electrode mixture paste similar to that of Example 1-1 was manufactured along with FIG. 5 using the positive electrode mixture paste prepared without passing through the second step. This is designated as Comparative Example 1-3.

  The following paste physical property evaluation was performed on each of the above examples. The results are shown in (Table 1).

(Paste viscosity measurement)
A B-type viscometer was used for the viscosity measurement. The rotor of the viscometer was immersed in the positive electrode mixture paste, and the viscosity (mPa / s) at the rotation speeds of 2 rpm and 20 rpm of the rotor was measured. Moreover, the ratio of the viscosity at 2 rpm to the viscosity at 20 rpm (hereinafter referred to as viscosity ratio) was obtained as an index of fluidity of the positive electrode mixture paste.

(Paste neglect test)
150 ml of 100 ml of the positive electrode mixture paste was placed in a cylindrical container having a bottom diameter of 5 cm and a height of 10 cm, and left at room temperature for 24 hours, and then the amount of the supernatant was taken out with a dropper and the weight was measured. The amount of the supernatant liquid at this time was used as an amount of water separation, and was used as an index for the sedimentation resistance of the positive electrode mixture paste.

図３のようにＣＭＣを先に投入して混練した比較例１−１の正極合剤ペーストは、ＣＭＣの鎖状構造が分断された後でキサンタンガムに取り込まれるので十分な効果を発揮できず、流動性が低下する正極合剤ペーストが得られる結果となった。また図４のようにＣＭＣのみでキサンタンガムを投入しない比較例１−２は粘度比が３以上であっても、水分離量の著しく大きい耐沈降性の悪いペーストが得られる結果となった。さらに図５のようにキサンタンのみでＣＭＣを投入しない比較例１−３は、粘度比が顕著に高く流動性の悪い正極合剤ペーストが得られる結果となった。

The positive electrode mixture paste of Comparative Example 1-1, in which CMC was first introduced and kneaded as shown in FIG. 3, could not exhibit a sufficient effect because it was taken into xanthan gum after the chain structure of CMC was broken. As a result, a positive electrode mixture paste with reduced fluidity was obtained. Further, as shown in FIG. 4, Comparative Example 1-2 in which xanthan gum was not added with only CMC as shown in FIG. 4 resulted in a paste having a significantly large water separation amount and poor sedimentation resistance even when the viscosity ratio was 3 or more. Further, as shown in FIG. 5, Comparative Example 1-3 in which CMC was not added only with xanthan resulted in a positive electrode mixture paste having a remarkably high viscosity ratio and poor fluidity.

  On the other hand, all of the positive electrode mixture pastes of Examples 1-1 to 1-9 prepared according to the production method of the present invention (FIGS. 1 and 2) exhibit excellent fluidity with a viscosity ratio of 5 or less. The settling resistance was also relatively good. Thus, the positive mix paste which has a favorable property improves the uniformity at the time of apply | coating or filling to a core material.

However, Example 1 in which the amount of xanthan gum as carbohydrate A was reduced to 0.03 parts by weight
In No. 6, since the sedimentation resistance due to the thickening action, which is the effect of the carbohydrate A, is reduced, the water separation amount of the paste is relatively remarkably increased. On the other hand, in Example 1-4 in which the amount of xanthan gum was increased to 0.22 parts by weight, the paste viscosity ratio was increased and the paste fluidity was slightly lowered. Therefore, the weight ratio of the cellulose derivative typified by CMC and the saccharide A typified by xanthan gum is preferably 1: 2 to 2: 1.

  Further, in Examples 1-8 and 1-9 in which the total amount of CMC and xanthan gum is 0.045 parts by weight, the effect of the thickener is hardly exhibited, the amount of paste water separation is slightly increased, and the settling resistance is compared. As a result, the results decreased. Therefore, the total amount of the cellulose derivative typified by CMC and the saccharide A typified by xanthan gum is preferably 0.05 parts by weight or more with respect to 100 parts by weight of nickel hydroxide.

(Example 2-1)
With respect to Example 1-1, the amount of CMC added to 100 parts by weight of nickel hydroxide powder is 0.2 parts by weight, the solid content ratio of xanthan gum is 0.3 parts by weight, and the weight ratio of CMC to xanthan gum is 1: A positive electrode mixture paste produced in the same manner as in Example 1-1, except that the total amount of CMC and xanthan gum was 0.5 parts by weight based on 1.5 parts by weight of nickel hydroxide powder. Example 2-1 And

(Example 2-2)
With respect to Example 1-1, the amount of CMC added to 100 parts by weight of nickel hydroxide powder is 0.2 parts by weight, the solid content ratio of xanthan gum is 0.4 parts by weight, and the weight ratio of CMC to xanthan gum is 1: 2. A positive electrode mixture paste produced in the same manner as in Example 1-1, except that the total amount of CMC and xanthan gum relative to 100 parts by weight of nickel hydroxide powder was 0.6 part by weight. .

(Example 2-3)
For Example 1-1, the amount of CMC added to 100 parts by weight of nickel hydroxide powder is 0.3 parts by weight, the solid content ratio of xanthan gum is 0.2 parts by weight, and the weight ratio of CMC to xanthan gum is 1. A positive electrode mixture paste produced in the same manner as in Example 1-1, except that the total amount of CMC and xanthan gum was 0.5 parts by weight with respect to 5 parts by weight of nickel hydroxide powder, Example 2-3. And

(Example 2-4)
For Example 1-1, the amount of CMC added to 100 parts by weight of nickel hydroxide powder is 0.4 parts by weight, the solid content ratio of xanthan gum is 0.2 parts by weight, and the weight ratio of CMC to xanthan gum is 2: 1. A positive electrode mixture paste produced in the same manner as in Example 1-1 except that the total amount of CMC and xanthan gum with respect to 100 parts by weight of nickel hydroxide powder was 0.6 parts by weight is referred to as Example 2-4. .

For each of the above examples, the same paste physical property evaluation as in Example 1 was performed. Moreover, about these Example 2-1 to 2-4 and the positive mix paste of Examples 1-1 and 1-3, it fills with the foamed nickel porous body which is a core material, 35 mm in width after drying and pressurization. A positive electrode for an alkaline storage battery having a theoretical capacity of 2800 mAh was produced by cutting the sheet into a length of 220 mm and a thickness of 0.6 mm. Further, a sulfonated polypropylene separator intervened between the positive electrode and a negative electrode having a theoretical capacity of 4200 mAh using a hydrogen storage alloy is spirally wound to produce an electrode group. After the insertion, an alkaline electrolyte composed of potassium hydroxide, sodium hydroxide and lithium hydroxide having a specific gravity of 1.26 was injected at a rate of 1.8 ml / Ah with respect to the positive electrode capacity to produce Ni / MH. The following battery discharge characteristics were evaluated. The results are shown in (Table 2).

(Battery discharge characteristics)
After Ni / MH of each example was allowed to stand for 24 hours, the following initial charge / discharge and activation charge / discharge of 10 cycles were performed in an atmosphere at 25 ° C., and then an internal resistance test was performed.
Initial charge / discharge conditions:
Charge-15 hours at 280 mA (1 hour after charge)
Charging / discharging conditions until discharge reaches −1.0 mA at 900 mA:
Charge-2 hours 30 minutes at 1400 mA-Internal resistance test until 1.0 V is reached at -2800 mA:
Charge-1 hour discharge at 1400 mA-20 seconds at -2800 mA, pause 5 minutes, charge-20 seconds at 2800 mA, discharge 5 minutes-discharge at 8400 mA, 20 seconds, pause-5 minutes, charge-20 seconds at 8400 mA, Pause 5 minutes Discharge-20 seconds at 14000 mA, Pause 5 minutes, Charge-14000 mA for 20 seconds, Pause 5 minutes Discharge-19600 mA for 20 seconds, Pause 5 minutes, Charge-19600 mA for 20 seconds, Pause 5 minutes The direct current internal resistance (DCIR) was calculated based on Ohm's law from the relationship between the four kinds of current values in the resistance test and the voltage after 10 seconds of discharge.

実施例１−１より増粘剤を減量した実施例１−３では、ＤＣＩＲが実施例１−１より低くなった。また、実施例１−１より増粘剤を増量した実施例２−1〜２−４は、いずれもＤＣＩＲが実施例１−１より高くなったが、特にＣＭＣとキサンタンガムの合計量が０．５重量部以上になるとＤＣＩＲが顕著に増加する結果となった。よって増粘剤の合計量は、水酸化ニッケル１００重量部に対して０．５重量部以下であることが好ましく、先に述べた耐沈降性の観点も含めて、増粘剤の合計量の範囲は０．０５〜０．５重量部であることが好ましい。

In Example 1-3 in which the thickener was reduced from Example 1-1, the DCIR was lower than in Example 1-1. In Examples 2-1 to 2-4 in which the thickener was increased from Example 1-1, the DCIR was higher than that in Example 1-1, but in particular, the total amount of CMC and xanthan gum was 0.00. When the amount was 5 parts by weight or more, DCIR was remarkably increased. Therefore, the total amount of the thickener is preferably 0.5 parts by weight or less with respect to 100 parts by weight of nickel hydroxide, including the above-described viewpoint of sedimentation resistance. The range is preferably 0.05 to 0.5 parts by weight.

  As mentioned above, when producing the positive mix paste for alkaline storage batteries containing the saccharide A and the cellulose derivative, the first step of kneading the nickel hydroxide powder, the additive powder, the saccharide A and water, By providing the second step of kneading the kneaded product of the step and the cellulose derivative aqueous solution, not only a high-quality positive electrode mixture paste can be obtained, but also by optimizing the amount, an alkali having excellent discharge characteristics can be obtained. It turns out that the positive electrode for storage batteries can be obtained.

  In this example, it was shown that xanthan gum acts as a carbohydrate A and CMC as a cellulose derivative, but even when other carbohydrate A or a cellulose derivative is used, the same effect as the present invention is obtained. Has been obtained.

  According to the production method of the present invention, the productivity of the positive electrode for alkaline storage battery is improved by stabilizing the positive electrode mixture paste for alkaline storage battery, and the discharge characteristic of the battery is improved by appropriately reducing the amount of thickener. it can. Therefore, it can be used as a power source for all devices, and its effect is great.

The flowchart which shows an example of the manufacturing method of the positive mix paste for alkaline storage batteries of this invention. The flowchart which shows an example of the manufacturing method of the positive mix paste for alkaline storage batteries of this invention. The flowchart which shows an example of the manufacturing method of the conventional positive mix paste for alkaline storage batteries The flowchart which shows an example of the manufacturing method of the conventional positive mix paste for alkaline storage batteries The flowchart which shows an example of the manufacturing method of the conventional positive mix paste for alkaline storage batteries

Claims (9)

Positive electrode composite for alkaline storage battery using nickel hydroxide powder as active material, water as solvent, saccharide consisting of straight chain containing monosaccharide and side chain containing saturated 6-membered ring structure and cellulose derivative as thickener A method for producing an agent paste,
A first step of kneading the nickel hydroxide powder;
The manufacturing method of the positive mix paste for alkaline storage batteries characterized by including the 2nd process of kneading | mixing the kneaded material and cellulose derivative of a said 1st process. The method for producing a positive electrode mixture paste for an alkaline storage battery according to claim 1, wherein the carbohydrate is added in the first step. The method for producing a positive electrode mixture paste for an alkaline storage battery according to claim 1, wherein the carbohydrate is added in the second step. 2. The method for producing a positive electrode mixture paste for an alkaline storage battery according to claim 1, wherein the weight ratio of the cellulose derivative to the saccharide is 2: 1 to 1: 2. 2. The positive electrode mixture for an alkaline storage battery according to claim 1, wherein the total of the cellulose derivative and the sugar is 0.05 to 0.5 parts by weight with respect to 100 parts by weight of the nickel hydroxide powder. Manufacturing method of paste. The method for producing a positive electrode mixture paste for an alkaline storage battery according to claim 1, wherein the cellulose derivative is carboxymethylcellulose and a modified product thereof. The method for producing a positive electrode mixture paste for an alkaline storage battery according to claim 1, wherein the sugar is xanthan gum. A positive electrode for an alkaline storage battery, wherein the positive electrode mixture paste for an alkaline storage battery obtained by the method for producing a positive electrode mixture paste for an alkaline storage battery according to any one of claims 1 to 7 is used. An alkaline storage battery using the positive electrode for an alkaline storage battery according to claim 8.

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