JP2003257432A - Manufacturing method for lead-acid battery negative electrode paste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for lead-acid battery negative electrode paste which improves properties of a negative electrode plate by adding barium sulfate uniformly to a negative electrode active material as a nucleating agent of the lead-acid battery negative electrode paste. <P>SOLUTION: This manufacturing method for lead-acid battery negative electrode paste is characterized in that agglomerate powders of barium sulfate are grinded and dissolved in a solution containing a surface active agent or an aqueous solution of a water-soluble organic solvent with a mortar or a ball mill and the resultant barium sulfate slurry is kneaded with the negative electrode active material to obtain an additive. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead acid battery negative electrode paste for improving the negative electrode characteristics of a negative electrode plate by uniformly adding barium sulfate, which is added to a lead acid battery negative electrode paste as a nucleating agent, to the paste. The present invention relates to a manufacturing method of.

[0002]

2. Description of the Related Art When a lead storage battery is used, especially when it is charged and discharged at a high temperature, the negative electrode active material contracts to reduce the reaction surface area or cracks occur on the negative electrode plate, which causes normal charge and discharge reaction and current collection. Will not work and will not work as a battery. Therefore, in order to improve discharge characteristics and life, a negative electrode plate is added with a lignin compound, for example, sodium ligninsulfonate or a derivative thereof, and barium sulfate as a nucleating agent of lead sulfate or barium carbonate and other precursors thereof. The barium salt of is added.

[0003]

In order to improve the negative electrode performance of the lead storage battery, it is required to uniformly mix the above-mentioned additives to be added to the negative electrode paste into the paste. Therefore, conventionally, barium salt powder was added to the raw material lead powder and dry-blended, and then water or diluted sulfuric acid was added and kneaded to disperse the barium salt in the paste. However, the added barium salt causes secondary condensation during storage, transportation, etc.,
Since this condensate is hard, it is a few μm when mixed with the active material.
Therefore, the large agglomerates are difficult to collapse during paste kneading, so negative negative barium sulfate agglomerates are present in the negative electrode active material. It was extremely difficult to disperse the particles uniformly, and as a result, the effect of suppressing the contraction of the negative electrode plate was not sufficiently obtained.

Therefore, a method of uniformly kneading barium sulfate in the negative electrode paste is disclosed in, for example, Japanese Patent Application Laid-Open No. 8-236119.
Japanese Patent Laid-Open No. 7-169464 (hereinafter referred to as the latter). However, the former proposal was a proposal to solve the former problem by synthesizing fine barium sulfate having a particle size of 1.0 μm or less of 80% or more, but 1.0 μm from the reaction solution obtained by the synthesis reaction.
It is very complicated to filter barium sulfate as particles having a particle size of m or less, wash with water, dry, grind, and classify, and the yield is low,
Therefore, there is a drawback that the cost becomes high and the practicality is lacking.

The latter proposal is a method in which a mixture of barium sulfate and lignin sulfonate powder is dispersed in water or dilute sulfuric acid and added to the raw material lead powder. This method is barium sulfate powder and lignin sulfonate powder. In order to make a suspension by pouring into water as a powder in a mixed state with stirring, barium sulfate powder first comes into contact with water having a large surface tension,
The barium sulfate powder became a hard agglomerate due to water, and the hard barium sulfate agglomerated powder remained in the size of the powder when mixed, and could not be crushed very finely. Therefore, it was difficult to expect that such a method would result in a relatively small agglomerate of barium sulfate and a suspension of lignin sulfonate and that barium sulfate would be dispersed in the negative electrode paste sufficiently evenly. Further, when the barium sulfate powder and the lignin sulfonate powder are mixed in the powder as they are and dispersed in diluted sulfuric acid, a suspension of the lignin sulfonate powder is obtained,
Even with this method, the particles could not be dispersed sufficiently uniformly.

[0006] As described above, when the barium sulfate powder and the lignin sulfonate powder are mixed as they are into water, the present inventor has a surface activity when the lignin sulfonate is dissolved in water. Since barium sulfate contains water before the sulfonate dissolves in water and exerts surface activity, even if the lignin sulfonate aqueous solution arrives at the barium sulfate powder, the barium sulfate will no longer absorb water, so it is sufficient. The barium sulphate agglomerate cannot enter into it, and as a result, the barium sulphate cannot be finely ground
The cause of the problem was identified, and further intensive research was conducted to complete the present invention.

[0007]

The present invention solves the above-mentioned drawbacks and provides a method for uniformly dispersing barium sulfate in a negative electrode paste. The invention according to claim 1 provides: In this method, a barium sulfate agglomerated powder is crushed in a solution containing a surfactant, and the obtained barium sulfate suspension is used as an additive for a negative electrode active material to produce a negative electrode paste for a lead storage battery.

Further, the invention according to claim 2 is such that the agglomerated powder of barium sulfate is crushed in a water-soluble organic solvent, and the obtained barium sulfate suspension is used as an additive of a negative electrode active material, and a negative electrode for a lead storage battery. It is a manufacturing method for manufacturing a paste.

[0009]

In the present invention, barium sulfate powder is first used as a dispersion medium to bring it into contact with an aqueous solution in which a surfactant having a small surface tension is dissolved or an aqueous solution in which a water-soluble organic solvent is added, so that the dispersion medium permeates between the primary particles of barium sulfate. To make it relatively easy to disintegrate, and then mechanically disintegrate to form a suspension in which barium sulfate is pulverized to near primary particles, and the suspension is used as an additive for the negative electrode paste to form barium sulfate. It is possible to produce a negative electrode paste in which is uniformly dispersed.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described. Barium sulfate powder, which is added as one of the negative electrode active materials for lead-acid batteries, is generally marketed in a strongly aggregated state. Such commercial products have a strong cohesive force and cannot be easily crushed. In the present invention, such commercially available barium sulfate powder is added to an aqueous solution containing a dispersion medium.

As the dispersion medium, a surfactant which does not adversely affect the negative electrode characteristics of the battery can be selected. As a surfactant that does not adversely affect the negative electrode characteristics of the battery,
As an anion system, alpha olefin sulfonate,
Surfactants such as lignin sulfonate, alkylbenzene sulfonate, alkylnaphthalene sulfonate-formaldehyde condensate, polystyrene sulfonate, alkyl sulfate ester salt, and alkyl ether sulfate can be selected.

As the nonionic surfactant, a surfactant such as higher alcohol or polyoxyalkylene glycol is suitable. The concentration of surfactant in water is 0.05-
10%.

In order to manufacture the negative electrode paste, first, barium sulfate powder is added to an aqueous surfactant solution in which the concentration of the surfactant is adjusted to 0.05 to 10%. Then, the barium sulfate powder containing the aqueous surfactant solution is ground (crushed) by a ball mill, a bead mill, a mortar or a lightning disintegrator, or a high speed crusher such as a crusher or a disper mill. When barium sulfate powder is added to an aqueous solution containing a surfactant, the surfactant is already dissolved in the aqueous solution.
The barium sulphate powder comes into direct contact with the surfactant (before absorbing water and forming lumps), and the surfactant penetrates between the primary particles of barium sulphate, making it relatively easy to disintegrate. It can be easily pulverized to near primary particles in time.

The suspension in which barium sulfate was crushed in this way was mixed with a water-mixed lead powder paste, or the suspension was diluted with all the water used in the paste to add lead powder to other additives. And dry-prepared dry mixture to form a negative electrode paste to prepare a negative electrode active material.

Next, a second embodiment of the present invention will be described.
I will explain it. The second embodiment has a water-soluble dispersion medium.
Use machine solvent. Negative electrode of battery as water-soluble organic solvent
Select one that does not adversely affect the characteristics. Battery negative
As a water-soluble organic solvent that does not adversely affect the properties,
Tanol, ethanol, (n⁻ , I⁻) Propanol,
Alcohols such as butanol, acetone, MIBK, etc.
Ketones are preferred. Concentration of water-soluble organic solvent against water
The degree is 0.05 to 10%.

First, the concentration of the water-soluble organic solvent is 0.05 to
Barium sulfate powder is added to an aqueous solution adjusted to 10%.
Then, the barium sulfate powder containing the aqueous solution mixed with the water-soluble organic solvent is ground (crushed) by a ball mill, a bead mill, a mortar, a thunder crusher or the like, or by a high speed crusher such as a crusher or a disper mill.

When barium sulfate powder is added to an aqueous solution containing a water-soluble organic solvent, the barium sulfate powder is brought into contact with the water-soluble organic solvent in the same manner as when barium sulfate powder is added to an aqueous solution containing a surfactant. The organic solvent penetrates between the primary particles of barium sulphate, making it relatively easy to disintegrate, so for a short time with a ball mill, bead mill, mortar or thunder disintegrator, or with a high-speed grinder such as a grinder or disper mill. In addition, it can be crushed and crushed (crushed) to near the primary particles.

The suspension obtained by crushing barium sulfate in this manner is mixed with a lead powder paste which has been kneaded with water, or the suspension is diluted with all the water used for the paste to add lead powder to other additives. And dry-prepared dry mix to make a paste.

Specific examples of the present invention will be described.

Example 1 9 g of a commercially available barium sulfate powder (average primary particle size: 1.0 μm) was added to a surfactant-containing aqueous solution obtained by completely dissolving 1.8 g of sodium ligninsulfonate as a surfactant in 20 cc of water. Then, the aqueous solution was completely permeated into the barium sulfate powder, and the barium sulfate was ground for 10 minutes to crush the barium sulfate.

Next, 900 g of ball mill type lead powder and 0.9 g of carbon black were put into an Oxmaster type kneader and dry mixed, and 80 cc of this dry mixture was added.
Of water is stirred and kneaded to prepare a lead water paste, the suspension is uniformly mixed with the paste, and finally 70 cc of dilute sulfuric acid having a specific gravity of 1.360 is added with stirring. A negative electrode paste was manufactured.

The prepared negative electrode paste was used as Pb-Sn-Ca.
Filled into a base alloy electrode substrate, temperature 35 ° C, humidity 95%
Aged for 24 hours to prepare a negative electrode plate. By combining the negative electrode plate thus prepared with a positive electrode plate, a separator, etc. manufactured by a conventional method, a lead-acid battery of 2 Ah was assembled at a rate of 5 hours so that the negative electrode would control the capacity. A mercury electrode was attached and the change in the negative electrode potential was measured.

Measurement was carried out at 0.4 A for 7.5 hours of charging,
Charge / discharge was performed in a constant temperature water bath at 60 ° C. until the negative electrode potential reached −0.8 V with respect to the mercury / mercurous sulfate electrode at 0.4 A, and the capacity change was measured. The measurement results are shown in FIG.

[0023]

Example 2 As a surfactant-containing aqueous solution containing 1.8 g of sodium ligninsulfonate (1.8 g) completely dissolved in 100 cc of water, the same commercially available barium sulfate powder (average primary particle size: 1. 0 μm) 9 g was added and the mixture was stirred for 30 minutes with a ball mill to prepare a suspension in which barium sulfate was crushed.

Next, 900 g of ball mill type lead powder and 0.9 g of carbon black were put into an Oxmaster type kneader and dry mixed, and the suspension was poured into this dry mixture while stirring. Knead and finally have a specific gravity of 1.3
While stirring 60 cc of dilute sulfuric acid, 70 cc was added to produce a negative electrode paste.

The prepared negative electrode paste was Pb as in Example 1.
-Sn-Ca system alloy electrode substrate is filled and temperature is 35 °.
A negative electrode plate was prepared by aging at C and a humidity of 95% for 24 hours.
By combining the negative electrode plate thus prepared with the positive electrode plate, separator, etc. manufactured by a conventional method, a lead-acid battery of 2 Ah is manufactured at a rate of 5 hours such that the negative electrode has a dominant capacity, and the battery is subjected to mercury / sulfuric acid first. A mercury electrode was attached and the change in the negative electrode potential was measured. The measurement was performed in the same manner as in Example 1. The measurement results are also shown in FIG.

[0026]

Comparative Example 1 9 g of the same barium sulfate powder as in the example and 1.8 g of sodium lignin sulfonate powder were dry-mixed,
It was poured into 100 cc of water and the above-mentioned JP-A-7-169464 was used.
The rotary blade type agitator disclosed in Japanese Patent No.
The mixture was stirred for 0 minutes to give a suspension.

Next, 900 g of ball mill type lead powder and 0.9 g of carbon black were put into an Oxmaster type kneader and dry mixed, and the suspension was poured into this dry mixture while stirring. Knead and finally have a specific gravity of 1.3
While stirring 60 cc of dilute sulfuric acid, 70 cc was added to produce a negative electrode paste. The prepared negative electrode paste was filled into an electrode substrate of a Pb-Sn-Ca alloy as in the above-mentioned example, and aged at a temperature of 35 ° C and a humidity of 95% for 24 hours to prepare a negative electrode plate.

The negative electrode plate thus prepared was combined with the positive electrode plate, separator and the like manufactured by a conventional method to manufacture a lead storage battery of 2 Ah at a rate of 5 hours so that the negative electrode would control the capacity. And charging at 0.4A for 7.5 hours,
Charge / discharge was performed in a constant temperature water bath at 60 ° C. until the negative electrode potential reached −0.8 V with respect to the mercury / mercurous sulfate electrode at 0.4 A, and the capacity change was measured. The measurement results are shown in FIG.

[0029]

Comparative Example 2 900 g of ball-mill type lead powder, 9 g of barium sulfate powder, 1.8 g of sodium ligninsulfonate powder, and 0.9 g of carbon black, which were the same as those in the example, were put into an Oxmaster-type kneader and dry-mixed. Pour 100 cc of water into the dry mixture while stirring and knead, then dilute sulfuric acid having a specific gravity of 1.360 with stirring at 70 c
c was added to produce a negative electrode paste. The prepared negative electrode paste was filled into an electrode substrate of a Pb-Sn-Ca alloy as in the above-mentioned example, and aged at a temperature of 35 ° C and a humidity of 95% for 24 hours to prepare a negative electrode plate.

The negative electrode plate thus prepared was combined with the positive electrode plate, separator and the like produced by a conventional method to manufacture a lead acid battery of 2 Ah at a rate of 5 hours so that the negative electrode would control the capacity. And charging at 0.4A for 7.5 hours,
Charge / discharge was performed in a constant temperature water bath at 60 ° C. until the negative electrode potential reached −0.8 V with respect to the mercury / mercurous sulfate electrode at 0.4 A, and the capacity change was measured. The measurement results are shown in FIG.

As is apparent from FIG. 1, Examples 1 and 2 of the present invention show high capacity retention. The phenomenon is that the dispersion medium first penetrates into the barium sulfate powder, and barium sulfate is present in the negative electrode active material in a fine and uniform manner, and the barium sulfate effectively acts as a crystal nucleus of lead sulfate generated by the discharge reaction. This is because the morphological change of the active material was suppressed because the Pb ²⁺ ion diffusion was suppressed, and it is considered that the high capacity was maintained.

On the other hand, in Comparative Example 1, the agglomerated barium sulfate powder was first dry mixed with the sodium lignin sulfonate powder, and then dissolved with water. In Comparative Example 2, all the materials to be blended were dry mixed. Melted in water from
Before the sodium lignin sulfonate aqueous solution, which is a dispersion medium, penetrates the barium sulfate powder, water covers the barium sulfate powder, and the barium sulfate powder becomes a solid mass, resulting in insufficient crushing and the addition of sodium lignin sulfonate. It is considered that this is the result of not obtaining sufficient effects. Further, as will be described later, the active material had a large morphological change, and some had cracks due to shrinkage, and some had a further large capacity decrease.

Next, the negative electrode after the above cycle test was taken out from the battery, and the contracted state and the barium sulfate dispersion state of the cross section were confirmed. Regarding the dispersion state of barium sulfate, a Ba mapping image was observed by EPMA, and the average diameter of the condensed mass was measured by image processing. The results are shown in Table 1.

[0034]

[Table 1]

As is clear from Table 1, the barium sulfates of Examples 1 and 2 were finely crushed, the shape change was small, and good cycle characteristics could be confirmed. On the other hand, Comparative Example 1,
With regard to No. 2, some crushing effect could be confirmed, but it was extremely insufficient, the contraction state of the active material of the electrode plate was poor, and cracks were also found.

Although the example using sodium lignin sulfonate as the dispersion medium in the above-mentioned embodiment has been described as a representative, the above-mentioned surfactant and water-soluble organic solvent were also tested and it was confirmed that the same effect could be obtained. confirmed.

[0037]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the agglomerated powder of barium sulfate is first crushed in a solution containing a surfactant or in an aqueous solution of a water-soluble organic solvent to obtain a barium sulfate suspension obtained. By using as a negative electrode additive, barium sulfate powder can be finely crushed, excellent negative electrode characteristics, and it is possible to produce a negative electrode paste that produces a negative electrode plate with little shape change even during charge / discharge cycles, which is industrially possible. It has an excellent effect.

[Brief description of drawings]

FIG. 1 is a graph showing a cycle test result of a lead storage battery.

[Explanation of symbols]

1 Test results of Example 1 2 Test results of Example 2 3 Test results of Comparative Example 1 4 Test results of Comparative Example 2

Claims (2)

[Claims] 1. A barium sulfate agglomerated powder is crushed in a solution containing a surfactant, and the obtained barium sulfate suspension is used as an additive for a negative electrode active material to produce a negative electrode paste for a lead storage battery. And a method for producing a negative electrode paste for a lead storage battery. 2. A barium sulfate agglomerated powder is crushed in a water-soluble organic solvent, and the obtained barium sulfate suspension is used as an additive for a negative electrode active material to produce a negative electrode paste for a lead storage battery. Manufacturing method of negative electrode paste for lead acid battery.