JPH10223211A - Lead storage battery and method of manufacturing the same - Google Patents

Abstract

(57) [Problem] It is known that early reduction in capacity of a battery using a lead-calcium alloy for a positive electrode grid is caused by the formation of a passive layer at the interface between the grid and the active material. ing. As a remedy, for example, a method of producing tetrabasic lead sulfate in an unactivated active material by performing high-humidity aging has been proposed. However, although this method has the effect of suppressing the early capacity decrease, it has the disadvantage that the chemical conversion is poor and sufficient initial performance cannot be obtained. SOLUTION: An active material layer containing tetrabasic lead sulfate is provided near the surface of a positive electrode grid made of a lead alloy, and the other active material layers use unformed positive electrode plates mainly containing tribasic lead sulfate. The unformed positive electrode plate is prepared by immersing a lead alloy positive electrode grid in dilute sulfuric acid, filling the grid with a lead oxide battery positive electrode paste obtained by uniformly kneading lead oxide and dilute sulfuric acid, and aging. To produce a lead-acid battery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a lead-acid battery using a lead-calcium alloy lattice and a method of manufacturing the same.

[0002]

2. Description of the Related Art At present, lead-acid batteries are used in various fields including those for automobiles and industries. Among them, automotive batteries have the highest demand, and are required to be lightweight, cost-saving, maintenance-free, have a long life, and have stable quality.

At present, the lattice alloys used in lead-acid batteries can be broadly classified into lead-antimony-based and lead-calcium-tin-based (hereinafter referred to as lead-calcium-based) alloys. Are known to differ significantly. That is, a lead-acid battery using a lead-antimony-based alloy positive electrode grid exhibits excellent characteristics in deep charge / discharge cycles, but has a disadvantage of large self-discharge. On the other hand, a lead-acid battery using a lead-calcium alloy positive electrode grid has excellent maintenance-free characteristics, such as low self-discharge and little liquid reduction during use. There is a disadvantage that the battery capacity may be reduced early if repeated.

[0004] The early decrease in capacity of a lead-acid battery using a positive electrode grid of a lead-calcium alloy causes the interface between the grid and the active material to preferentially discharge to form a passive layer when deep discharge is repeated. It is known to happen. It is also known that this phenomenon is observed when a lattice made of a lead-antimony alloy containing 1.2% or less of antimony is used.
That is, it is a phenomenon peculiar to a lead alloy lattice substantially containing no antimony. Also, it is known that when an expanded grid is used for the positive electrode, the early capacity reduction is more likely to occur than when a cast grid is used.

Conventionally, lead-acid batteries have been manufactured as follows. That is, the lead alloy lattice is filled with a paste obtained by kneading a lead powder having a degree of oxidation (weight% of lead monoxide) of 60 to 95% with dilute sulfuric acid, aging and drying to form an unformed electrode plate. I do. A battery assembled using these components is formed into a battery case with an amount of electricity of 200 to 400% of the theoretical amount of electricity of the positive electrode active material to obtain a charged battery.

[0006]

When a lead-calcium alloy is used as the positive electrode grid, the aging step described above is improved, for example, by subjecting the unactivated active material to tetrabasic sulfuric acid by aging at high temperature and high humidity. Methods for producing lead have been proposed. However, according to this method, the bondability of the interface between the lattice and the active material is improved, and the early capacity reduction is suppressed. There is a disadvantage that sufficient initial performance cannot be obtained due to poor chemical conversion.

[0007]

DISCLOSURE OF THE INVENTION The lead storage battery of the present invention solves the above-mentioned problems and is an active plate containing a tetrabasic lead sulfate near the surface of a lead alloy positive electrode grid as a lead storage battery electrode plate. It has a material layer, and the other active material layers are characterized by using an unformed positive electrode plate mainly composed of tribasic lead sulfate.

Further, the lead storage battery of the present invention comprises a lead alloy positive electrode paste obtained by immersing a lead alloy positive electrode grid in dilute sulfuric acid and then uniformly kneading the grid with lead oxide and dilute sulfuric acid. Filling and aging to generate tetrabasic lead sulfate in the active material layer near the surface of the lattice, and the other active material layers using an unformed positive electrode plate mainly composed of tribasic lead sulfate It is characterized by being manufactured.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The lead-acid battery according to the present invention comprises an active material layer containing tetrabasic lead sulfate near the surface of a positive electrode grid made of a lead alloy, and an active material mainly containing tribasic lead sulfate in other portions. An unformed positive electrode plate having a material layer is used. The production method is as follows. After immersing a lead alloy positive electrode grid in dilute sulfuric acid, the grid is filled with a lead oxide battery positive electrode paste obtained by uniformly kneading lead oxide and dilute sulfuric acid, and aging. As a result, an unformed positive electrode plate having the above configuration is obtained, and a lead storage battery is assembled using the unformed positive electrode plate. By doing so, it is possible to suppress a rapid decrease in the capacity of a lead-acid battery using a lead-calcium alloy lattice for the positive electrode, and to provide a lead-acid battery excellent in charge-discharge cycle life performance.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.

First, a ball mill type lead powder was uniformly kneaded with water and dilute sulfuric acid to prepare a positive electrode paste. The amount of sulfate groups in the positive electrode paste was 5% by weight of lead powder. These pastes are mixed with ordinary Pb-Ca-Sn by a usual method.
The casting grid using the alloy was filled.

On the other hand, according to the present invention, after the grid was immersed in dilute sulfuric acid, an electrode plate filled with the positive electrode paste was also manufactured. Here, the specific gravity of the diluted sulfuric acid soaked in the lattice is 1.40 (20
° C).

The above two types of electrode plates are heated at 40.degree.
The aging was performed for 24 hours in aging rooms at different temperatures of ° C and 70 ° C. The relative humidity in the aging room was 100% at any temperature. The aged electrode plate was dried in a 50 ° C. drying room (relative humidity 25%) for 3 days to obtain eight types of unformed positive electrode plates shown in Table 1.

The size of the electrode plate used here is height 110
mm, the width was 108 mm, and the thickness was 2.0 mm, and the density of the activated material was set to be about 3.5 g / cm ³ .

[0015]

[Table 1] Four unformed positive electrode plates / cell, Pb-Ca-Sn
An automotive lead-acid storage battery 36B20 (5 hour capacity: 28 Ah) specified in JIS D 5301 was assembled using five normal non-formed negative electrode plates / cell using an alloy lattice.
Next, these batteries were subjected to battery case formation, and a 5 hR discharge test was repeated. In the 5 hR discharge test, the battery was discharged at 5.6 A to a final voltage of 10.5 V, and the discharge capacity was examined.
The charge / discharge cycle of charging to 135% of the discharge electricity amount was repeated. The test temperature was 25 ° C.

FIG. 1 shows the transition of the 5 hR discharge capacity of these batteries. In a battery using a positive electrode plate with a conventional formulation,
If the aging temperature is 60 ° C. or lower (NO. 1 to 3), the capacity is relatively early but the capacity is reduced relatively early, and
Aged at 0 ° C. (NO. 4) exhibited excellent life performance although the initial capacity was small. On the other hand, in the positive electrode plate in which the grid was immersed in dilute sulfuric acid and then filled with paste, the aging temperature was 50%.
And those at 60 ° C. (Nos. 6 and 7) had sufficient initial capacity and exhibited excellent life performance. However, 40 ° C. (NO.1, 5) and 70 ° C. (NO. 4,
The ripening of 8) showed the same capacity change regardless of the presence or absence of the dilute sulfuric acid treatment of the lattice.

In order to investigate the cause of such a large difference in the capacity transition during the charge / discharge cycle, the cross sections of these unformed positive electrode plates were observed and investigated. The outline of the observation results of these unformed positive electrode plates is shown in FIGS. FIG. 2 is a schematic diagram showing the distribution of the active material composition in the positive electrode plate used in this example.

[0018] Of the electrode plates filled with the paste without impregnating the positive electrode grid with diluted sulfuric acid, those having an aging temperature of 60 ° C or less (N
O. 1-3) The composition of the whole active material as shown in FIG. 2 (a) consisted mainly 3PbO · PbSO ₄ · H ₂ O and t-PbO. Further, an electrode plate aged at 70 ° C. (NO.
4) the composition of the whole active material as shown in consisted mainly of 4PbO · PbSO ₄ and t-PbO FIG 2 (b).

On the other hand, as for the electrode plate in which the positive electrode grid is immersed in dilute sulfuric acid and then filled with the paste, the one having an aging temperature of 40 ° C. (No. 5) has an active material layer near the grid as shown in FIG. PbO · PbSO ₄ is a 3PbO · PbSO ₄ · H
_It consists of ₂ O and t-PbO, and the other part is 3PbO · Pb
It consisted of SO ₄ .H ₂ O and t-PbO. As shown in FIG. 2 (d), in the electrode plate (NO. 6, 7) in which the aging temperature was 50 and 60 ° C., the active material layer near the lattice was 4 PbO ·
PbSO ₄ and 3PbO · PbSO ₄ · H ₂ O and t-Pb
Consists of O, the other part is 3PbO · PbSO ₄ · H ₂ O
And t-PbO. In the electrode plate (No. 8) in which the aging temperature was 70 ° C., as shown in FIG. 2E, the active material layer near the lattice was composed of 4PbO.PbSO ₄ and PbO.PbSO.
₄ and t-PbO, the other part is 4PbO.PbS
It consisted of O ₄ and t-PbO.

Table 2 summarizes the observation results. In Table 2, PbO.PbSO ₄ , 3PbO.PbSO ₄
· H ₂ O, and each as abbreviations of 4PbO · PbSO ₄ using 1BS, the 3BS and 4BS.

[0021]

[Table 2] The following was found from the relationship between these observations and the life performance of the battery.

The characteristics of the electrode plates (NO. 1 to 3, 5) having a sufficient initial capacity but having a reduced capacity early are that the active material near the lattice and most of the other active materials are both 3PbO.PbS.
O ₄ · H ₂ O (3BS: tribasic lead sulfate), which has a small initial capacity but a long service life (N
O. Features of 4,8) lattice near and most other active material 4PbO · PbSO ₄ Both (4BS: was to consist of tetrabasic lead sulfate). On the other hand, has sufficient initial capacity and features active material of the lattice near 4PbO · PbSO ₄ of the electrode plate (NO.6,7) was long-lived (4B
S: tetrabasic consists lead sulfate), most other active materials _{3PbO · PbSO 4 · H 2 O} (3BS: was to consist of tribasic lead sulfate). In addition, PbO / PbSO
₄ The presence of (1BS: monobasic lead sulfate) and t-PbO appeared to have little effect on battery performance.

From the above, according to the present invention, an active material layer containing tetrabasic lead sulfate is provided near the surface of the positive electrode grid made of a lead alloy, and the other active material layers are mainly composed of tribasic lead sulfate. It is considered that the initial capacity and the life performance of the lead storage battery (NO. 6, 7) using the chemical conversion positive electrode plate were both excellent for the following reasons. That is, sufficient initial performance is obtained because most of the unchemically formed active material is made of tribasic lead sulfate having excellent chemical conversion properties, and the interface between the lattice and the active material is well joined by tetrabasic lead sulfate. It is probable that early capacity reduction was unlikely to occur.

The ripening temperature at which the tetrabasic lead sulfate was formed was 50 ° C. or higher in the vicinity of the lattice, and was 70 ° C. in the other portions. The reason why the formation temperature of tetrabasic lead sulfate differs depending on the formation site is considered to be due to the difference in the amount of sulfuric acid in the paste. In other words, when the paste was filled after the grid was immersed in dilute sulfuric acid in advance, the amount of sulfuric acid near the grid was relatively large, which is considered to be the lower temperature for generating tetrabasic lead sulfate than other parts. Can be

[0025]

As described above, the use of the lead-acid battery according to the present invention makes it possible to prevent the early decline in capacity of the lead-acid battery, improve the life performance and stabilize the quality. Its industrial value is enormous.

[Brief description of the drawings]

FIG. 1 is a graph showing a change in 5hR discharge capacity.

FIG. 2 is a schematic diagram showing a distribution of an active material composition in a positive electrode plate.

Claims (2)

[Claims] An active material layer containing tetrabasic lead sulfate is provided in the vicinity of the surface of a lead alloy positive electrode lattice, and the other active material layers use unformed positive electrode plates mainly composed of tribasic lead sulfate. A lead-acid battery characterized by the above-mentioned. 2. A lead alloy positive electrode grid is immersed in dilute sulfuric acid, and then the grid is filled with a lead acid battery positive electrode paste obtained by uniformly kneading lead oxide and dilute sulfuric acid, followed by aging. By using this, an unformed positive electrode plate is used in which tetrabasic lead sulfate is generated in the active material layer near the surface of the lattice, and the other active material layers are mainly made of tribasic lead sulfate. Manufacturing method of storage battery.