JP2001332252A - Manufacturing method for negative electrode plate of lead battery, and the lead battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a negative electrode plate for a lead battery, in which a shrink resistant effect of the negative electrode plate for the lead battery that has a mixture of barium sulfate is improved. SOLUTION: After preparing a reaction mixture that comprises a deposited barium sulfate in the reaction of a material containing a barium compound with diluted sulfuric acid, the reaction mixture is added in preparing an active substance paste for the negative electrode, mixed to form the active substance paste for the negative electrode and filled on a porous substrate in the conventional way, so as to manufacture the negative electrode plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a negative electrode plate of a lead storage battery and a lead storage battery.

[0002]

2. Description of the Related Art Since a negative electrode plate of a lead-acid battery undergoes a charge / discharge reaction accompanied by dissolution and precipitation, when a charge / discharge cycle is performed, the generated Pb ²⁺ ions diffuse from the place where they originally exist and go to another place. There is a phenomenon that the active material shrinks due to precipitation. When the active material shrinks, the reaction surface area decreases and the electrode plate cracks, so that normal charge / discharge reaction and current collection cannot be performed, and the battery does not operate. To prevent such inconvenience, commercially available barium sulfate powder, which is a nucleus of lead sulfate generated at the time of discharge, is added to the active material of the negative electrode plate, and is uniformly present to prevent shrinkage of the negative electrode plate. Although it has been known for a long time, commercially available barium sulfate powder causes secondary agglomeration at the time of production, storage or transportation, and when added at the time of preparing a negative electrode active material paste, it is 1 micron or less effective as a nucleus. In the kneading, the particles are hardly uniformly mixed in the active material paste, and therefore, the effect of suppressing the shrinkage of the negative electrode plate manufactured by filling the active material paste into the lead lattice substrate is reduced. The inconvenience of reduction could not be avoided. To solve this inconvenience, Japanese Unexamined Patent Publication No.
According to the invention of JP-A-111263, in the production of a negative electrode plate for a lead-acid battery, when kneading a negative electrode active material paste, a barium hydroxide aqueous solution and sulfuric acid are directly added to the paste, and the paste is kneaded and reacted. It discloses that a negative electrode plate in which the life of the negative electrode plate is improved by uniformly generating fine barium sulfate particles without secondary aggregation is disclosed therein.

[0003]

However, Japanese Patent Application Laid-Open No.
In the invention of JP-A-8-111263, since barium hydroxide and dilute sulfuric acid are directly added to the negative electrode active material paste,
Part of the added sulfuric acid is consumed by reacting with Pb or PbO, which is a negative electrode active material, without reacting with barium hydroxide, and is expected to react with barium hydroxide and sulfuric acid as raw materials to deposit barium sulfate. The reaction yields low yields while the sulfuric acid concentration is low, which has the disadvantage that the barium sulfate particles produced are relatively large. Therefore, the disadvantages of the above-described conventional technology are solved, and barium and sulfuric acid used as raw materials are reacted without waste to reliably generate and precipitate a predetermined amount of primary particles of barium sulfate. It is desired to develop a method for manufacturing a negative electrode plate in which a paste uniformly mixed in a paste is easily and quickly prepared, and a negative electrode plate having an improved shrink-proof effect is prepared using the paste.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and reacts the amounts of barium and sulfuric acid used as raw materials without wasting them to produce a predetermined amount of barium sulfate. The negative electrode active material paste can be obtained by adding a certain amount of barium sulfate to the negative electrode active material paste and uniformly dispersing and mixing the negative electrode active material paste. Provide a method for manufacturing a negative electrode plate that results in a lead-acid battery, a reaction solution in which barium sulfate is precipitated by a reaction between barium ions and sulfate ions, or a reaction solution obtained by concentrating the same.
Alternatively, a step of preparing a barium sulfate reaction liquid in the form of a slurry separated by filtration, and then adding the kneaded mixture at the time of preparing the negative electrode active material paste and kneading to prepare a negative electrode active material paste is characterized in that: And Furthermore, the present invention is characterized in that, in the above-described method for producing a negative electrode plate for a lead storage battery, a barium sulfate dispersant is added to the reaction solution and stirred. Further, the present invention provides a method for producing a negative electrode plate for a lead storage battery in which aggregation of barium sulfate is surely prevented, wherein the concentration of sulfuric acid in the reaction solution is 1 M or more. . Further, the present invention provides a lead-acid battery that maintains a high capacity and has a long life, and is characterized in that the above-described negative electrode plate of the present invention is used as a negative electrode plate.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention comprises the following first steps:
A reaction liquid is prepared by reacting barium ions of barium-based raw material with sulfate ions of dilute sulfuric acid to precipitate barium sulfate. As a barium-based raw material that generates barium ions in a sulfuric acid aqueous solution, at least one selected from metal barium, barium hydride, barium halide, barium sulfide, barium oxide, barium hydroxide, barium carbide, and other barium compounds is used. As the dilute sulfuric acid used to generate sulfate ions, dilute sulfuric acid having a sulfuric acid concentration of 1 M or more sulfuric acid remains in the reaction solution after the reaction.

At room temperature, one type of barium-based raw material, preferably powder, is gradually added to the sulfuric acid contained in the container,
The mixture is reacted with sulfuric acid while stirring to precipitate barium sulfate, thereby obtaining a reaction solution containing a predetermined amount of barium sulfate in the aqueous sulfuric acid solution. In this case, in particular, in order to deposit barium sulfate of 1 micron or less effective as a nucleus, the concentration of sulfuric acid in the diluted sulfuric acid used as a raw material is determined by reacting the sulfuric acid with one of barium-based raw materials at room temperature, Ensure that at least 1 M sulfuric acid remains in the solution. In this case, a predetermined amount of barium sulfate can be reliably obtained by vigorously stirring the sulfuric acid and the barium-based raw material at room temperature. If the concentration of sulfuric acid in the reaction solution is less than 1 M, there is no problem in the case where the sulfuric acid concentration is immediately added to the active material paste and kneaded, but when left in the state of the reaction solution, the crystal of primary particles of barium sulfate grows and becomes 1 μm or more. It is not preferable. As described above, according to the present invention, a predetermined amount of barium-based raw material and a predetermined concentration of sulfuric acid are directly reacted as described above, so that a reaction solution containing a predetermined amount of barium sulfate having a particle size of 1 micron or less can be reliably obtained. .

After the above reaction solution is prepared in this manner, the reaction solution is added to a lead powder mainly composed of PbO, and an additive such as a conductive agent, a binder and water are added and kneaded, and the mixture is kneaded. It is added when preparing the substance paste, and the whole is kneaded. In such a case, a predetermined amount of barium sulfate composed of fine particles having a particle size of 1 micron or less can be surely added, and barium sulfate is uniformly dispersed and mixed without secondary aggregation and is of good quality. A negative electrode active material paste capable of improving the shrinkage-preventing effect of the negative electrode plate is reliably obtained. In the preparation of this negative electrode active material paste, when barium sulfate is added in an amount of 0.1 to 2.0% by mass with respect to the negative electrode active material, the negative electrode plate particularly maintains the capacity of the lead storage battery for a long time at a high capacity. Is obtained.

The reaction solution containing barium sulfate can be added to the negative electrode active material paste as it is, or as a small volume reaction solution obtained by concentrating the reaction solution using a membrane filter or the like. Or the reaction liquid is filtered to separate most of the liquid, and a mud-like reaction liquid composed of barium sulfate wetted with a small volume of sulfuric acid as a residue is selected as desired, This is preferably added at the time of preparing the negative electrode active material paste.

When the reaction solution containing barium sulfate in the container is left for a long time, the reaction solution containing 1 .mu.
m or less, barium sulfate was settled and deposited, and it was observed that it became a relatively redispersible large solid mass, but a dispersant such as carboxymethylcellulose was added to this,
By stirring and mixing once, even if left for a long time,
It was confirmed that sedimentation and aggregation of barium sulfate could be prevented and the barium sulfate was dispersed in the reaction solution and maintained in a suspended state. Therefore, it is common to immediately add the reaction solution after the completion of the above-mentioned reaction work to the negative electrode active material paste. However, if necessary, the reaction solution or the concentrated reaction solution or the mud-like reaction solution may be added to the reaction solution. In other words, by adding and stirring a dispersing agent to the barium sulfate slurry, it is not necessary to immediately add these to the negative electrode active material paste after the completion of the above-mentioned reaction work, so that they can be stored and used as needed. The workplace is convenient.

As the dispersant, in addition to the above-mentioned CMC,
For example, methyl cellulose, polyethylene oxide,
Polyvinyl alcohol, sodium ligninsulfonate, sodium naphthalenesulfonate and the like can be used, and the amount is preferably 0.01 to 1% by mass.

The lead negative electrode paste obtained by kneading the barium sulfate-containing reaction solution, the concentrated reaction solution, or the slurry-like reaction solution prepared as described above is filled in a lead grid substrate by a conventional method, and the mixture is aged, dried, and heated. The negative electrode plate of the present invention is obtained by pressing.

The negative electrode plate is laminated on the positive electrode plate and the separator via a separator to form an electrode plate group, accommodated in a lead battery case, and covered to obtain a lead storage battery of the present invention. When a charge-discharge cycle test was performed on the lead-acid battery using the negative electrode plate of the present invention, a higher capacity was maintained compared to a lead-acid battery incorporating a conventional negative electrode plate,
It was confirmed that lead storage batteries with improved cycle life could be manufactured.

Next, a specific embodiment of the present invention will be described in detail. Preparation of reaction solution: reagent grade barium carbonate powder 845.5
g of sulfuric acid in a container, and vigorously stirred, with a sulfuric acid concentration of 6.5M.
Was added to 10 liters of diluted sulfuric acid, and both were reacted to precipitate barium sulfate. At the time of injection, carbon dioxide gas was generated violently, but the generation became moderate over time, and the generation finally stopped. Thus, stirring was continued for 24 hours to complete the reaction. As a reaction solution, about 10 liters of an emulsion-like reaction solution which became cloudy due to precipitation of fine particles of barium sulfate was obtained. The reaction solution contained 1000 g, ie, 1 kg, of barium sulfate and the sulfuric acid concentration was about 6M. Reaction solution A
And Barium carbonate powder 725.8 of the above-mentioned reagent grade
In place of g, 725.8 g of reagent grade barium sulfide was used, and this was charged into 10 liters of the same 6.5 M dilute sulfuric acid, and allowed to react in the same manner as described above to obtain 1000 g, that is, 1 kg of barium sulfate. Contains and sulfuric acid concentration about 6M
About 10 liters of the reaction solution was obtained. This was designated as reaction solution B. Using a membrane filter, 10 liters of the above reaction solution A was used to obtain 1 liter of a concentrated reaction solution containing 1 kg of barium sulfate. This was designated as reaction solution C. Further, 5 g of polyvinyl alcohol as a dispersant, that is, 0.5% was added to 1 liter of the reaction solution C, and the mixture was stirred.
A viscous reaction solution in which 1 kg of barium sulfate in suspension and a dispersant were dissolved, which was allowed to stand at 0 ° C. for 10 days, was obtained. This was designated as reaction solution D.

An X-ray diffraction pattern of the precipitates in the reaction solutions A, B, and C was measured to confirm the composition, and it was confirmed that the precipitates were barium sulfate. Also,
When the particle size distribution of barium sulfate in these reaction solutions A, B, and C was measured using a laser diffraction type particle size distribution meter capable of measuring a particle size of 0.1 μm or more, the measurement was very fine and was below the lower limit of measurement. It was possible. In addition, SEM observation of the above reaction solution D confirmed that barium sulfate retained primary particles without aggregating. As a result of many comparative tests, in general, it is possible to suppress the growth of barium sulfate crystals in the reaction solution and keep it at 1 μm or less by maintaining the sulfuric acid concentration in the reaction solution at 1 M or more. understood. From this, it was found that it is preferable to use the slurry-like reaction solution of barium sulfate wetted with a small amount of 1 M or more sulfuric acid, which is a residue after filtration of the reaction solution, without washing with water. Preparation of negative electrode active material paste: 1 kg of barium sulfate described above
Each of 1 liter of reaction solution A and 6.5 liters of B having a sulfuric acid concentration of 6.5 M was prepared by a ball mill method using a negative electrode active material, that is, 100 K of lead powder mainly containing lead oxide.
g, in other words, 1% by weight of barium sulfate is added to the negative electrode active material, and 0.1 kg of carbon powder as a conductive agent and 0.2 kg of sodium ligninsulfonate as a thickener are added. Was kneaded to prepare negative electrode active material pastes A ′ and B ′, respectively. 1 liter of the above-mentioned barium sulfate containing 1 kg of concentrated reaction solution C having a sulfuric acid concentration of 6.5 M was added to 100 kg of the above-mentioned lead powder,
In other words, barium sulfate is 1% by weight based on the weight of the negative electrode active material.
0.1 kg of carbon powder and 0.2 kg of sodium ligninsulfonate were further added.
Was added, and the whole was kneaded to prepare a negative electrode active material paste C ′. One liter of the above reaction liquid D was added to 100 kg of the above-mentioned lead powder, in other words, 1 wt% of barium sulfate was added to the negative electrode active material, and 0.1 kg of carbon powder and 0.2 kg of sodium ligninsulfonate were further added. Then, 9 L of 6.5 M diluted sulfuric acid was further added, and the whole was kneaded to prepare a negative electrode active material paste D ′.

For comparison, a negative electrode active material paste was prepared by the following preparation method. Comparative Example 1 1 kg of the special-grade reagent barium sulfate powder was added to the negative electrode active material 1 described above.
00Kg, in other words, barium sulfate was added at 1% by weight to the negative electrode active material, and carbon powder 0.1K was added.
g and 0.2 kg of sodium ligninsulfonate were added, and further, 10 L of 6.5 M diluted sulfuric acid was added, and the whole was kneaded to prepare a negative electrode active material paste E. still,
SEM observation showed that most of the barium sulfate powder from the primary particles was agglomerated to several tens of μm. Comparative Example 2 The reaction liquid A was filtered to collect barium sulfate as a residue, washed with water and dried, and the obtained barium sulfate powder was pulverized with a mill to obtain barium sulfate powder. In this case, the primary particles of barium sulphate were so fine that the filtration process took a considerable amount of time, and a part of the particles passed through the filter paper, so that the yield was less than 70%. Therefore, the same reaction solution A as described above was newly prepared, barium sulfate powder was obtained in the same manner, and a part of the barium sulfate powder was added to the previously obtained barium sulfate powder so that the total barium sulfate powder became 1 kg. did. 1 kg of this barium sulfate was added to 1% by weight of the negative electrode active material, and a negative electrode active material paste F was prepared in the same manner as in Comparative Example 1 below. Most of the barium sulfate powder used as a raw material was tens of μm by SEM observation.
m. Comparative Example 3 845.5 g of barium carbonate powder and 10 liters of dilute sulfuric acid having a sulfuric acid concentration of 6.5 M were mixed with 100 kg of the negative electrode active material,
It was added to a mixture of 0.1 kg of carbon powder and 0.2 kg of sodium ligninsulfonate, and the whole was sufficiently kneaded to prepare a negative electrode active material paste G.

Production of negative electrode plate: Each of the above-mentioned negative electrode active material pastes A ', B', C ', D', E, F, G
Each of the negative electrode active material pastes is used as a porous substrate according to a conventional method, for example, a lead alloy lattice substrate, for example, Pb-Sn-
After filling into a lattice substrate of a Ca-based alloy, each of the negative plates A ", B", C ", D", E ', F', and G was aged for 24 hours in an atmosphere at a temperature of 35 ° C and a humidity of 95%. '.

Manufacture of lead-acid batteries: For each of the negative plates A ", B", C ", D", E ', F', G ',
Each negative electrode plate is laminated with a positive electrode plate manufactured by a conventional method via a separator, accommodated in a battery case, and a 2 Ah lead-acid battery A, B, C, 5A at a 5-hour rate such that the negative electrode becomes dominant in capacity.
D, E, F, and G were produced respectively. Each of the batteries was provided with a mercury / mercuric sulfate electrode so that a change in negative electrode potential could be measured.

Charge / discharge cycle test: Batteries A, B, C, D, E, F, and B using the respective negative plates A ", B", C ", D", E ', F', and G '. For G, each of them is 4
Placed in a 5 ° C. constant temperature water bath, a charge / discharge cycle test was repeated in which charging at 0.4 A for 7.5 hours and discharging at 0.4 A until the negative electrode potential reached −0.8 V were performed. The change in the discharge capacity was measured. The result is shown in FIG.

As is apparent from FIG. 1, the discharge capacity of the comparative batteries E, F, and G using the comparative negative electrodes E ', F', and G 'decreases with an increase in the charge / discharge cycle. 10
While the discharge capacity is reduced to half of the initial capacity in 0 cycles, the batteries A, B, C and D of the present invention using the negative plates A ", B", C "and D" of the present invention maintain a high capacity. However, it can be seen that the charge / discharge cycle life is extended. This is because barium sulfate composed of very fine primary particles acting as crystal nuclei of lead sulfate generated during discharge is uniformly dispersed in the negative electrode plates A ", B", C ", and D" of the present invention. On the other hand, barium sulfate in the comparative negative electrode plates E ′ and F ′ has a particle size of several μm even if the addition amount is the same as in the case of the present invention. It is considered that the primary particles are mixed in a state of aggregated particles having a particle size of from about 10 to several tens [mu] m, and the effect of preventing shrinkage of the negative electrode plate is inferior. The battery using the negative electrode plate G 'for comparison has a shorter cycle life than the battery of the present invention. This is probably because the obtained barium sulfate particles are relatively large.

Next, a reaction solution 10 containing 1 kg of barium sulfate precipitated by reacting 845.5 g of the above barium carbonate with 10 liters of dilute sulfuric acid having a sulfuric acid concentration of 6.5 M and comprising 6.5 M of dilute sulfuric acid. The negative electrode active material paste A ′ prepared by adding 1% by weight of barium sulfate to the negative electrode active material using 1 liter was filled, and in addition to the lead-acid battery A using the manufactured negative electrode plate A ″, barium carbonate was added. The amount and the sulfuric acid concentration in 10 liters of dilute sulfuric acid were changed, and
A negative electrode plate was prepared in which the amount of barium sulfate added to the negative electrode active material was different, and lead storage batteries H, I, J, K, and L using the respective negative electrode plates were manufactured. The same charge / discharge cycle test as described above was performed, and the capacity retention ratio at the 100th cycle relative to the capacity at the first cycle was determined. The results were as shown in Table 1.

[0021]

[Table 1]

As is apparent from Table 1, the addition amount of barium sulfate to the negative electrode active material is too small at 0.05% by mass and the effect of addition is insufficient, and at 3.0% by mass, the addition amount of barium sulfate is insufficient for the negative electrode active material. A battery with an improved cycle life could not be obtained because the amount of barium sulfate as a conductor was too large. When the amount of addition is in the range of 0.1% to 2.0%, the capacity retention ratio is 8
A good battery of 0% or more was obtained.

[0023]

As described above, according to the present invention, first, a reaction liquid is prepared by reacting a barium-based raw material with sulfuric acid to produce barium sulfate as primary particles. Since the obtained reaction solution, its concentrated solution or barium sulfate separated by filtration is added at the time of preparing the negative electrode active material paste, the raw materials are allowed to react without wasting and the expected amount of barium sulfate is deposited. In addition, a predetermined amount of barium sulfate having a particle size of 1 μm or less can be uniformly dispersed and mixed in the lead active material paste without agglomeration. A negative electrode plate can be manufactured, and an excellent battery with an improved charge / discharge cycle life is provided. In the production of the negative electrode plate of the present invention described above, when a dispersant is added to the reaction solution, barium sulfate does not precipitate and solidify even when the reaction solution is left for a long time, and the negative electrode is activated immediately after the production of the reaction solution. There is no need to add it to the preparation of the substance paste, and the effect can be added at any time as desired. When the concentration of sulfuric acid in the reaction solution is 1 M or more, growth of barium sulfate crystals can be suppressed.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the number of charge / discharge cycles and the discharge capacity of various lead-acid batteries using various negative electrode plates filled with a negative electrode active material paste prepared by various preparation methods.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kozo Sogabe 23-6 Tsukubashi-cho, Iwaki-shi, Fukushima Pref. GA02 GA10 GA11 GA12 HA10

Claims (4)

[Claims] 1. A reaction solution in which barium sulfate is precipitated by a reaction between barium ions and sulfate ions, or a reaction solution in which barium sulfate is concentrated, or a slurry barium sulfate reaction solution obtained by filtration of the reaction solution is prepared. A method for producing a negative electrode plate for a lead-acid battery, comprising the steps of: adding the mixture during the preparation of the negative electrode active material paste; and kneading the mixture to prepare the negative electrode active material paste. 2. The method for producing a negative electrode plate of a lead storage battery according to claim 1, wherein a barium sulfate dispersant is added to the reaction solution and stirred. 3. The method according to claim 1, wherein the concentration of sulfuric acid in the reaction solution is 1 M or more. 4. A lead-acid battery comprising a negative electrode plate obtained by the method for producing a negative electrode plate of a lead-acid battery according to claim 1.