JP5545975B2 - Positive electrode active material for lead storage battery and positive electrode plate for lead storage battery comprising the same - Google Patents

Description

The present invention relates to a positive electrode active material used for a positive electrode plate of a lead storage battery and a positive electrode plate for a lead storage battery formed by filling the positive electrode active material.

Lead-acid batteries have a long history with nickel-cadmium batteries, and still occupy the mainstream of accumulators because of their reliability that comes from their stable performance as well as their low cost. For example, it is widely used as an SLI power source for automobiles, a mobile power source used in small electronic devices and electric vehicles, or a backup stationary power source that operates when a power source of a computer or the like is stopped.

In recent years, lead storage batteries used for these power supplies and the like have been increasingly demanded for high output and large capacity, and lead storage batteries having improved characteristics as well as volume and weight have become necessary. Thus, various studies have been made to improve the characteristics of lead-acid batteries. One example is efforts to improve the utilization of active materials in the positive electrode plates of lead-acid batteries.

The production of the positive electrode plate of a lead-acid battery usually involves preparing a lead paste by kneading lead powder mainly composed of metallic lead and lead oxide with water and dilute sulfuric acid, and then using the lead paste. After filling a lattice body made of lead or a lead alloy, an unformed sheet is produced through an aging and drying process. The utilization factor of the active material in the positive electrode plate depends on the number of pores generated between the particles, that is, the porosity, and the higher the porosity, the higher the utilization factor. The reason for this is that the pores of the active material are blocked by the sulfate generated during discharge, and the sulfuric acid necessary for the discharge reaction is less likely to diffuse, so that the greater the porosity, the more ensured the diffusion of sulfuric acid. It is believed that.

Therefore, a technique has been conventionally proposed in which expanded graphite is added to lead paste, and graphite is expanded during chemical conversion to increase pores. However, when graphite is expanded, the bonding force between the particles constituting the active material is reduced, and the active material structure becomes weak. As a result, particularly when deep charge / discharge is repeated, the active material is detached from the positive electrode plate, the adhesion between the active material and the lattice is lowered, the current collection efficiency is lowered, and the conductivity between the active materials is lowered. There was a problem that the life as a storage battery would be shortened. As a similar technique, alkali metal and alkaline earth metal sulfates are added at the time of paste kneading, the maximum temperature at the time of kneading is 40 ° C. or less, and the moisture content at the end of kneading is 12 to 14.5% by weight. And a lead storage battery in which a metal oxide MO ₂ selected from Sn, Pb, Ge, Cr, Os, Mn or Ru is added to the positive electrode active material (Patent Document 2) It has been known. However, even in these attempts, a sufficient lead storage battery has not been obtained yet.

JP-A-7-122270 JP 2000-182615 A

The present invention, when used in a positive electrode plate of a lead-acid battery, does not cause a decrease in the bonding force between the active material particles and forms pores with an optimal diameter, so that it exhibits a very good utilization rate. The present invention provides a positive electrode active material for lead storage battery and a positive electrode plate for lead storage battery obtained by filling the positive electrode active material.

The present inventors tried various examinations about how to increase the number of holes in the active material used for the positive electrode plate of the lead storage battery from the viewpoint of increasing the utilization rate of the lead storage battery. As a result, the present inventors pay attention to the fact that the positive electrode active material paste produced by adding dilute sulfuric acid and water to lead powder containing metal lead and lead oxide as the main components and kneading is alkaline. Then, if a metal powder, for example, aluminum powder is added to the positive electrode active material paste, the aluminum powder reacts with the positive electrode active material paste and dissolves to form voids in the active material. Even if there is a metal powder that does not completely dissolve in the solution, it is found that when the diluted sulfuric acid that is the electrolyte is injected, it reacts and completely dissolves, and further, pores are formed. For example, the inventors have found that the battery life is not reduced as seen in conventional graphite addition, and have completed the present invention.

That is, the present invention
(1) In the metallic lead powder and a positive electrode active material for lead-acid battery comprising a lead oxide powder, further look-containing metallic powder, the average particle diameter of the metal powder is a 10 to 500 [mu] m, and the metal powder The positive electrode active material for a lead storage battery, wherein the content is 0.5 to 2.0% by mass in terms of aluminum volume with respect to the lead oxide powder (here, the mass in terms of aluminum volume) And the value obtained by replacing the mass of the metal powder with the mass of aluminum of the same volume) .

As a preferred embodiment,
(2) The positive electrode active material for a lead storage battery according to (1), wherein the metal powder is one or more selected from the group consisting of aluminum, magnesium, zinc, and tin,
(3) The positive electrode active material for a lead storage battery according to (1), wherein the metal powder is aluminum,
( 4 ) The positive electrode active material for a lead storage battery according to any one of (1) to (3), wherein the average particle size of the metal powder is 10 to 300 μm,
( 5 ) Any one of the above (1) to ( 4 ), wherein the content of the metal powder is 0.5 to 1.5% by mass in terms of aluminum volume with respect to the lead oxide powder. The positive electrode active material for lead-acid batteries described in (Herein, the mass in terms of aluminum volume refers to a value obtained by replacing the mass of the metal powder with the mass of aluminum of the same volume),
( 6 ) The positive electrode active material for a lead storage battery according to any one of (1) to ( 5 ), wherein the porosity after chemical conversion is 55% or more and less than 60%,
( 7 ) The positive electrode active material for a lead storage battery according to any one of (1) to ( 5 ), wherein the porosity after chemical conversion is 56.5 to 58.0%,
( 8 ) A lead-acid battery positive plate formed by filling a paste prepared by adding dilute sulfuric acid and water to the positive-electrode active material for a lead-acid battery according to any one of the above (1) to ( 7 ). Can be mentioned.

The positive electrode active material for a lead storage battery of the present invention, when used for a positive electrode plate of a lead storage battery, does not cause a decrease in the binding force between active material particles, and forms pores with an optimal diameter. A good utilization rate can be exhibited.

The positive electrode active material for a lead storage battery of the present invention is characterized in that the positive electrode active material for a lead storage battery containing a conventional metal lead powder and lead oxide powder further contains a metal powder. The positive electrode active material and metal powder are kneaded using dilute sulfuric acid and water to prepare a positive electrode active material paste. The type of the metal powder is not particularly limited as long as it is a material that can be used as a positive electrode active material paste and can react with dilute sulfuric acid during the formation to dissolve the metal powder to form pores. Preferably, at least one selected from the group consisting of aluminum, magnesium, zinc and tin is used. However, lead is excluded.

The lower limit of the average particle size of the metal powder is preferably 10 μm. If it is less than the above lower limit, when the positive electrode active material for a lead storage battery of the present invention is kneaded with dilute sulfuric acid and water, the reaction proceeds rapidly, the metal powder is dissolved, and it becomes difficult to form pores. Normally, in lead-acid batteries, as discharge progresses, lead dioxide, which is the active material, changes to lead sulfate and expands in volume, thereby reducing the pore size and insufficiently diffusing the electrolyte into the active material. This causes the phenomenon that the discharge ends. However, if the average particle diameter of the metal powder is equal to or greater than the above lower limit, even if the volume expansion in which lead dioxide changes to lead sulfate occurs, if the pore diameter formed by the metal powder is sufficiently large, the diffusion of the electrolyte solution Will not be disturbed. In particular, the larger the thickness of the electrode plate as in the case of a large electrode plate, the greater the effect that the average particle diameter of the metal powder is greater than or equal to the above lower limit, which greatly improves the active material utilization rate. obtain.

On the other hand, the upper limit of the average particle diameter of the metal powder is preferably 500 μm, more preferably 300 μm. If the above upper limit is exceeded, the substrate surface is likely to be exposed and the substrate is likely to be corroded, thereby causing problems such as short circuit due to elongation of the substrate and peeling of the active material. The adhesion between the substance and the substrate is deteriorated, and a problem of capacity reduction due to peeling of the active material occurs.

The lower limit of the content of the metal powder is, in terms of aluminum volume mass, preferably 0.2% by mass with respect to the lead oxide powder contained in the positive electrode active material for a lead storage battery of the present invention. With respect to the lead oxide powder contained in the positive electrode active material for a lead storage battery of the present invention, the aluminum volume conversion mass is preferably 2.0 mass%, more preferably 1.5 mass%. If it is less than the said minimum, the porosity in the positive electrode active material for lead acid batteries cannot fully be raised, and initial capacity cannot be raised. On the other hand, when the above upper limit is exceeded, the porosity increases unnecessarily, resulting in a decrease in the bonding force between the active materials and a decrease in the bonding force between the active material and the substrate lattice, and the increase in the number of pores results in the substrate surface. May easily be exposed and react with the electrolyte to promote corrosion. Here, the lead oxide contained in the positive electrode active material for a lead storage battery of the present invention is PbO. Moreover, aluminum volume conversion mass means the value which replaced the mass of the metal powder with the mass of the aluminum of the same volume. That is, when the metal powder is any type of metals, the mass of the volume of 1.0 cm ³ are those mass Like 2.700 g of aluminum volume 1.0 cm ^3. For example, when magnesium is converted into an aluminum volume, the mass of magnesium, which is 1.738 grams, is calculated as 1.0 cm ³ .

The lower limit of the porosity after chemical conversion of the positive electrode active material for a lead storage battery of the present invention is preferably 55%, more preferably 56.5%, and the upper limit is preferably less than 60%, preferably 58.0%. is there. If it is less than the lower limit, the effect of increasing the capacity of the lead storage battery is poor, and if the upper limit is exceeded, the space volume is large, so that the adhesion between the active materials is deteriorated, which may cause early capacity reduction. . Here, the porosity after chemical conversion of the positive electrode active material for a lead storage battery in the present invention is a paste obtained by kneading the active material with water and dilute sulfuric acid as shown in the following examples. The ratio of the void | hole in the active material formed after an unformed board is manufactured through a ripening and a drying process after it fills in, and then it converts into chemicals is said.

The positive electrode active material for a lead storage battery according to the present invention is added with dilute sulfuric acid and water in accordance with a conventionally known method to be kneaded and pasted, and the positive electrode for a lead storage battery is filled with the paste in a grid for a positive electrode plate. It is made a board. There is no restriction | limiting in particular in the manufacturing method of this positive electrode plate for lead acid batteries, and the manufacturing method of lead acid battery using this positive electrode plate, A conventionally well-known method can be used.

In the following examples, the present invention will be described in more detail, but the present invention is not limited to these examples.

(Example)
Battery materials and test methods used in Examples and Comparative Examples are as follows.

Battery material <Board>
Both the positive electrode substrate and the negative electrode substrate used have a substantially square-shaped active material filling space. The portion of the regular square hole has a diameter of 6 to 12 mm. The dimensions of the positive electrode plate are 40.0 × 73.0 mm for the electrode portion, 4.0 × 12.0 mm for the ear portion, the thickness of the electrode portion is 2.0 mm, and the thickness of the ear portion. Is 2.0 mm. On the other hand, the dimensions of the negative electrode substrate are 40.0 × 75.0 mm for the electrode portion, 4 × 12.0 mm for the ear portion, and the thickness of the electrode portion and the ear portion is both 2.0 mm. Both the positive electrode substrate and the negative electrode substrate are made of lead-calcium alloy.
<Retainer mat separator>
Paper is made of fine glass short fibers having an average diameter of 1 μm or less manufactured by Nippon Sheet Glass Co., Ltd., and formed into a mat shape. The retainer mat separator has a thickness of 1.5 mm when pressurized to 40 kPa.
<Battery>
It is made of ABS resin and has dimensions of 25.0 mm × 45.0 mm × 120.0 mm.

Test method <Float life test>
Each control valve type lead-acid battery was charged at a constant voltage of 2.23 V so that the ambient temperature was kept constant at 60 ° C. in a thermostatic bath. Then, a capacity confirmation test at 0.1 CA (atmosphere temperature 25 ° C.) is conducted every month from the start of the test, and the month from the start of the test to the time when the discharge capacity becomes 70% or less of the initial discharge capacity. The number was taken as the battery life.
<Initial capacity test>
Each control valve-type lead-acid battery was measured at its initial capacity by measuring the capacity when the battery voltage reached 1.8V at a discharge current of 0.5A, with the ambient temperature kept constant at 25 ° C in a thermostatic chamber. The capacity value was used.
<Porosity>
An automatic porosimeter (manufactured by Shimadzu Corporation, Auto Bore IV9500 series) was used, and measurement was performed by a mercury intrusion method.
<Average particle size>
It measured using the laser diffraction type particle size distribution measuring apparatus (LMS-24 type | mold by Seishin Enterprise Co., Ltd.). And the particle diameter corresponding to 50% in the cumulative value with respect to the total particle volume was defined as the average particle diameter (Dp50).

Evaluation method <Initial capacity ratio (%)>
The initial discharge capacity value of Example 1 was set to 100%, and the values of each Example and Comparative Example were calculated.
<Comprehensive evaluation>
Evaluation 1 was made when the initial capacity ratio was less than 95%, evaluation 2 was made when it was 95% or more and less than 100, and evaluation 3 was made when it was 100% or more. Further, the evaluation is 1 when the battery life is less than 10 months, the evaluation 2 when it is 10 months or more and less than 13 months, and the evaluation 3 when it is 13 months or more. And the product of the evaluation value of initial capacity ratio and the evaluation value of battery life was shown as comprehensive evaluation.

Example 1
100 parts by weight of lead powder consisting of 30% by weight of metal lead powder and 70% by weight of lead oxide powder (PbO) as an active material, 10 parts by weight of water and 20 parts by weight of dilute sulfuric acid (specific gravity: 1.27) As a positive electrode active material paste, an aluminum powder (average particle size: 100 μm) was added in an amount of 1.0 mass% with respect to the lead oxide and sufficiently kneaded. Next, the paste was filled in the positive electrode substrate, and then aged for 24 hours at 40 ° C. and a humidity of 80%, followed by drying to produce an unformed positive electrode plate.

Meanwhile, a negative electrode active material paste was prepared by a known method. Then, the paste was filled in a negative electrode substrate, then aged for 24 hours at 40 ° C. and 80% humidity, and then dried to produce an unformed negative electrode plate.

Three unchemically produced positive electrode plates and four unformed negative electrode plates thus produced were alternately laminated via retainer mat separators, and the same polarity ear rows were welded to form an electrode plate group. Manufactured. The electrode plate group is housed in a battery case made of ABS resin, and the battery case and the lid are adhered and sealed with a resin, and then a sulfuric acid electrolyte (20 grams of sodium sulfate) is put into the battery case from the liquid port of the lid. Was dissolved in 1 liter of water and the specific gravity was 1.21 at 20 ° C.) until the electrode plate group was sufficiently impregnated. This was overcharged at 25 ° C. by 200% of the theoretical capacity to form a battery case, and a 2V-5Ah control valve type lead storage battery was manufactured. The porosity of the positive electrode active material after conversion was 57%.

A float life test was performed on the manufactured control valve type lead acid battery.

(Examples 2 to 4)
The same operation as in Example 1 was performed except that the aluminum powder as the metal powder was replaced with magnesium powder, zinc powder and tin powder having the same volume as the amount of aluminum powder added in Example 1, respectively. A 2V-5Ah control valve type lead storage battery was obtained by battery case formation. The porosity of the positive electrode active material after conversion was 57%.

(Comparative Example 1)
The same operation as in Example 1 was carried out except that no metal powder was added. A 2V-5Ah control valve type lead storage battery was obtained by battery case formation. The porosity of the positive electrode active material after chemical conversion was 50%.

The results of Examples 1 to 4 and Comparative Example 1 are shown in Table 1.

Examples 1-4 change the kind of added metal powder. Here, the compounding amounts of magnesium, zinc and tin in Examples 2 to 4 were the same as the volume of aluminum compounded in Example 1. Both the initial capacity ratio and the battery life were similar and good, and the overall evaluation was 9 as high. On the other hand, in Comparative Example 1 in which no metal powder was added, the initial capacity ratio was remarkably low, and the overall evaluation was remarkably low. In Comparative Example 1, since no metal powder was added, it is considered that no voids were formed in the positive electrode active material.

(Examples 5 to 14)
The same operation as in Example 1 was performed except that a mixture of two or more kinds of metal powders was added in the amounts shown in Table 2. In any case, a 2V-5Ah control valve type lead-acid battery was obtained by battery case formation, and the porosity of the positive electrode active material after formation was 57%. The total amount of metal powder added in each example was the same as the amount of aluminum powder added in Example 1. And in Examples 5-10, so that the compounding quantity of two types of metal powder may become the same amount by volume, and in Examples 11-13, the compounding quantity of three types of metal powder becomes the same amount by volume. And in Example 14, it mix | blended so that the compounding quantity of four types of metal powder might become the same quantity by volume.

The results of Examples 5-14 are shown in Table 2.

Examples 5 to 9 are each using a mixture of two different kinds of metal powders, and Examples 10 to 13 are each using a mixture of three different kinds of metal powders, and are implemented. Example 14 uses a mixture of four different metal powders. Even when a plurality of metal powders were combined or any of the metal powders was used, all of them showed a remarkably high overall evaluation as in Example 1.

(Examples 15 to 20)
As shown in Table 3, the same procedure as in Example 1 was performed except that the average particle size of the aluminum powder to be added was variously changed. In any case, a 2V-5Ah control valve type lead-acid battery was obtained by battery case formation, and the porosity of the positive electrode active material after formation was 57%.

(Examples 21 to 26)
As shown in Table 3, the same procedure as in Example 1 was performed except that a mixture of two types of metal powders of aluminum and magnesium was used and the average particle size of these metal powder mixtures was variously changed. In any case, a 2V-5Ah control valve type lead-acid battery was obtained by battery case formation, and the porosity of the positive electrode active material after formation was 57%. Here, the total amount of the two types of added metal powders of aluminum and magnesium was set to the same volume as the aluminum added in Example 1, and the amounts of aluminum and magnesium were set to the same volume. .

The results of Examples 15 to 26 are shown in Table 3. In addition, Examples 1 and 5 which are results of using metal powder having an average particle diameter of 100 μm are also shown.

In Examples 1 and 15 to 20, the average particle diameter of the aluminum powder was changed from 5 μm to 600 μm. In Examples 5 and 21 to 26, the average particle diameter of the mixture of the aluminum powder and the magnesium powder was 5 μm. To 600 μm. In any case, when metal powders having an average particle diameter of 5 μm and 600 μm were used, the overall evaluation was somewhat worse. However, the effect of the present invention was not impaired.

In Examples 15 and 21, in which a metal having a small particle size with an average particle size of 5 μm was used, the battery life was good, but the initial capacity ratio was low. This is because the pores formed after the formation are very small in diameter, and due to the volume expansion from lead dioxide to lead sulfate that occurs as the discharge progresses, the pores are blocked, resulting in insufficient diffusion of the electrolyte into the active material. It depends. On the other hand, in Examples 20 and 26 using a metal having a large particle size with an average particle size of 600 μm, the initial capacity ratio was good, but the battery life was short. This is because relatively large pores are formed by a large particle size of 600 μm, and therefore the substrate surface is partially exposed, and the substrate portion reacts with sulfuric acid present in the pores, and lattice corrosion proceeds. It is thought that.

In addition to the above metals and metal mixtures, the same experiment was performed using magnesium, zinc and tin powder alone and various mixtures of aluminum, magnesium, zinc and tin powder. It was.

(Examples 27 to 32)
As shown in Table 4, the same procedure as in Example 1 was performed except that the amount of aluminum powder added was variously changed. In either case, a 2V-5Ah control valve type lead storage battery was obtained by battery case formation. The porosity of the positive electrode active material after chemical conversion was 54.0 to 60.5%.

(Examples 33 to 39)
As shown in Table 4, in Examples 33 to 37, two types of metal powders of aluminum and magnesium were set to 1: 1 in volume ratio, and in Examples 38 and 39, these two types of metal powders were mixed in volume ratio. And 1.0: 0.5 and 0.5: 1.0, respectively, and the same procedure as in Example 1 was performed except that the amount of the metal powder mixture added was variously changed. In either case, a 2V-5Ah control valve type lead storage battery was obtained by battery case formation. The porosity of the positive electrode active material after chemical conversion was 54.5 to 61.5%.

The results of Examples 27 to 39 are shown in Table 4. In addition, Example 1 in which the amount of aluminum powder added is 1.00% by mass, and a mixture of aluminum powder and magnesium powder in a volume ratio of 1: 1, and the mixture was added in Example 1 Example 5 added in the same volume as the volume of was also shown.

In Examples 1 and 27 to 32, the amount of aluminum powder added was changed from 0.10% by mass to 2.50% by mass. In Example 27 with a small addition amount and Example 32 with a large addition amount, the overall evaluation values were somewhat poor, but none of them impaired the effects of the present invention. In Example 27, the initial capacity ratio is considered to be somewhat lowered because the porosity is slightly lower than 55%. On the other hand, in Example 32, since the porosity is 60% or more and the space volume is large, there is a tendency that the adhesion between the active materials tends to deteriorate, and there is a slight decrease in the initial capacity ratio and a decrease in the life. . In Examples 5 and 33 to 39, the addition amount of the mixture of aluminum powder and magnesium powder was changed from 0.12% by mass to 3.00% by mass. The same tendency as in the case of aluminum powder alone was shown.

In addition to the above metals and metal mixtures, the same experiment was performed using magnesium, zinc and tin powder alone and various mixtures of aluminum, magnesium, zinc and tin powder. It was.

The positive electrode active material for a lead storage battery of the present invention can exhibit a remarkably good utilization rate. Accordingly, since the positive electrode plate for a lead storage battery filled with the positive electrode active material for the lead storage battery and the lead storage battery using the same can also exhibit a remarkably good utilization rate, in the future, there will be many in the field of lead storage batteries. Can be expected.

Claims (4)

In the positive electrode active material for a lead storage battery comprising a metallic lead powder and lead oxide powder, further look-containing metallic powder, the average particle diameter of the metal powder is a 10 to 500 [mu] m, and the content of the metal powder The positive electrode active material for lead-acid batteries, characterized in that it is 0.5 to 2.0% by mass in terms of aluminum volume with respect to the lead oxide powder (wherein the mass in terms of aluminum volume is metal powder) ) Is replaced with the mass of aluminum of the same volume) . The positive electrode active material for a lead storage battery according to claim 1, wherein the metal powder is at least one selected from the group consisting of aluminum, magnesium, zinc and tin. The positive electrode active material for a lead storage battery according to claim 1 or 2 , wherein the porosity after chemical conversion is 55% or more and less than 60%. A positive electrode plate for a lead storage battery comprising a paste prepared by adding dilute sulfuric acid and water to the positive electrode active material for a lead storage battery according to any one of claims 1 to 3 and kneading the mixture.