JP2002124251A - Positive electrode for lead-acid battery and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead-acid battery with enhanced service life performance by inhibiting self-discharge or decrease in electrolytic solution to the same extent as in the event that a Pb-Ca alloy current collector is used. SOLUTION: This positive electrode for the lead-acid battery is made by coating a positive-electrode current collector for the lead-acid battery with an active-material paste containing boron of 0.005 to 0.5 wt.%. The current collector has a surface layer of an alloy composition different from that of its base material on at least a part of a surface of the base material. The base material is made of a lead alloy not containing Sb or lead, and the surface layer is made of a lead alloy containing an alkaline earth metal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a lead storage battery.

[0002]

2. Description of the Related Art Conventionally, a Pb-Sb alloy has been used as a current collector of a positive electrode plate in a lead storage battery. However, batteries using this alloy have a large self-discharge and decrease in electrolyte,
It has been difficult to use for maintenance-free type batteries and sealed batteries. Therefore, in order to suppress self-discharge and a decrease in the amount of the electrolytic solution and to achieve maintenance-free operation, for example, a lead alloy containing no Sb, such as a Pb-Ca alloy containing about 0.12 wt% or less of Ca, or pure Pb is used. It became so.

[0003]

However, the capacity of a battery using a lead alloy containing no Sb for the positive electrode current collector may decrease earlier than the capacity of a battery using a Pb-Sb alloy. The reason for this is that the adhesion between the positive electrode current collector and the active material deteriorates, and the current collector surface is selectively discharged (a passive layer is formed). Therefore, it is considered effective to improve the adhesiveness between the positive electrode current collector and the active material in order to improve the life performance of a battery using a lead alloy containing no Sb for the positive electrode current collector.

As one method for this improvement, Pb
It has been proposed to form a Pb-Sb-based alloy layer on the surface of a -Ca-based alloy positive electrode current collector (JP-A-63-148).
557). It is known that by using this method, the capacity can be prevented from being reduced at an early stage, and the liquid reduction characteristics can be improved as compared with those using a current collector of a Pb-Sb-based alloy. However, even in this method, since Sb is used although only on the surface of the current collector, Sb elutes into the electrolytic solution and precipitates on the negative electrode to lower the hydrogen overvoltage.
There was a problem that self-discharge and liquid reduction could not be suppressed as well as a system-based alloy current collector.

The present invention solves the above-mentioned problems, and provides a lead-acid battery in which self-discharge and decrease in electrolyte are suppressed to the same level as when a Pb-Ca-based alloy current collector is used, and the life performance is improved. It is intended to do so.

[0006]

The invention according to claim 1 is a positive electrode current collector for a lead storage battery having a surface layer of an alloy composition different from that of the substrate on at least a part of the surface of the substrate, The base material is a lead alloy or lead not containing Sb,
A positive electrode plate for a lead storage battery, characterized in that an active material paste containing 0.005 to 0.5% by weight of boron is applied to a positive electrode current collector whose surface layer is a lead alloy layer containing an alkaline earth metal. It is.

According to a second aspect of the present invention, in the positive electrode plate for a lead storage battery according to the first aspect, the alkaline earth metal is C
a, the amount of which is 0.2 to 5.0 wt%.

A third aspect of the present invention is a method for producing a positive electrode plate for a lead-acid battery according to the first or second aspect, wherein a boron oxide is added to the active material by adding a peroxo borate compound during preparation of the active material paste. Is included.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A positive electrode plate according to the present invention is provided with a lead alloy layer containing an alkaline earth metal on the surface of a base material of a positive electrode current collector made of a lead alloy containing no Sb, and a boron compound added thereto. It can be carried out by applying the active material paste prepared as described above.

A lead-acid battery using a positive electrode plate manufactured by this method has a significant improvement in life performance as compared with a lead-acid battery manufactured by a conventional method. Note that the current collector is a general term for an electrode substrate holding an active material and having a current collecting function, and a grid-like or foil-like thing is usually used.

By providing a lead alloy layer containing a very large amount of alkaline earth metal on the surface of the positive electrode current collector, the adhesion between the positive electrode active material and the positive electrode current collector can be improved, and the life performance can be improved. I understand that. However, if the active material further contains boron, some reaction occurs between lead, boron, and the alkaline earth metal, and the adhesion between the active material and the lattice and the binding between the active materials are significantly improved. I understand.

As for the amount of Ca in the surface layer, 0.2
If the content is less than 0 wt%, the effect of improvement is insufficient.
2 to 5.0 wt% is preferred.

The method of adding boron to the active material is not limited to compounds such as boric acid and boride, but it is preferable to add a peroxoboric acid compound during the preparation of the paste. If the amount of boron in the active material is less than 0.005 wt%, the improvement effect is insufficient, and if it is more than 0.5 wt%, the volume energy density of the positive electrode decreases. It is suitable.

The present invention is not limited to a specific lead-acid battery, but can be applied to any type of lead-acid battery such as a liquid type, a closed type, and a clad type. The effect of the present invention does not change even when an additive such as lead red, litharge, Sn compound or graphite, which has been used to improve the performance of the positive electrode, is included when preparing the active material paste.

[0015]

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

First, a base material of 10 mm thick Pb-
On the surface (one side) of a continuous cast plate of 0.07 wt% Ca-1.3 wt% Sn alloy, 0.3 mm thick Pb-1 wt%
The Ca alloy sheets were overlapped and rolled by a rolling roller to produce an integrated rolled sheet having a thickness of 1.0 mm. As a result, a thickness of about 30 μm
A rolled sheet having a Pb-1 wt% Ca alloy surface layer was prepared. FIG. 1 is a perspective view of the rolled sheet, and FIG. 2 is a cross-sectional view thereof. In the figure, 1 is a surface layer and 2 is a substrate.

Next, the produced rolled sheet was developed into a mesh using a rotary expanding machine to form a grid.
These lattices were filled with a paste produced by kneading a lead powder, a boron compound, and dilute sulfuric acid, aged, and dried to produce a positive electrode plate. In addition, sodium peroxoborate was used as the boron compound, and the amount of boron after the formation was 0, 0.001, 0.005, 0.1, 0.5,
It was added so as to be 1 wt%. Five of these positive electrode plates and 1.0 mm thick Pb-0.07 wt% Ca-1.
Using a reciprocating expander, a 3 wt% Sn alloy rolled sheet is mesh-developed into a grid and filled with a paste prepared by kneading lead powder mixed with lignin sulfonic acid, BaSO ₄ and carbon and dilute sulfuric acid. , Aging, and drying, and six negative electrode plates were alternately laminated via a fine glass fiber separator to form an electrode plate group. These electrode plates were inserted into a battery case, and a predetermined amount of diluted sulfuric acid was injected to form a chemical solution.
A sealed lead-acid battery of V30Ah was manufactured.

These batteries were discharged at 10A (1 / 3C
A) for 1.5 hours, charging is performed at a constant current of 10 A and discharging amount of 9
After charging 0%, 20% of the discharge amount at a constant current of 1.5A
Was charged in a two-stage constant current system.
The test was performed in a water bath at 40 ° C. Also, 50
The discharge capacity was checked with a current of 10 A (１ ／ CA) for each cycle, and the life was defined as the life when the discharge duration was less than 1.5 hours. . For comparison, a battery was prepared in the same manner for a grid having no surface layer on the surface of a substrate, and subjected to a test. Table 1 shows a list of the batteries subjected to the test and the test results.

[0019]

[Table 1]

A Pb-1 wt% Ca alloy layer is provided on the surface of the current collector, and boron is contained in the positive electrode active material in an amount of 0.005 to 0.005%.
Batteries (I, J, K) containing 0.5 wt% have significantly improved life performance compared to the case of using each alone, and Pb
-Compared to the battery (A) without the Ca surface layer and without the addition of sodium peroxoborate, the battery had three times or more the life performance. The amount of liquid reduction was about the same as that of the conventional product, there was no problem of electrolyte depletion during battery use, and there was no adverse effect on sealing and maintenance characteristics.

In the embodiment, the case where the current collector according to the present invention is applied to an expanded lattice is shown.
The present invention is not limited to this, and the same effect can be obtained when the present invention is applied to a punched grid or a sheet-shaped lead alloy current collector. The same effect can be obtained even when the surface layer is formed by spraying on the surface of the casting grid, dipping in a molten lead alloy, electroplating, or the like.

Further, in this experiment, a Pb-1 wt% Ca alloy layer was tested as a lead alloy layer containing an alkaline earth metal.
The effect is the same even with an alloy layer. The effect does not change even if Sn is contained in the Pb-Ca alloy layer.

[0023]

As described above, according to the present invention, it is possible to obtain an excellent lead-acid battery capable of significantly extending the life performance.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a rolled sheet for producing a current collector according to the present invention.

FIG. 2 is a cross-sectional view showing an example of a rolled sheet for producing a current collector according to the present invention.

[Description of Signs] 1 Surface layer 2 Base material

Claims (3)

[Claims] 1. A positive electrode current collector for a lead storage battery having a surface layer having an alloy composition different from that of the base material on at least a part of the surface of the base material, wherein the base material is a lead alloy or lead not containing Sb. The surface layer is a lead alloy layer containing an alkaline earth metal, the positive electrode current collector, boron is 0.005 to 0.5 wt
% Of a positive electrode plate for a lead-acid battery, to which an active material paste containing 0.1% by weight is applied. 2. The positive electrode plate for a lead-acid battery according to claim 1, wherein the alkaline earth metal is Ca, and its amount is 0.2 to 5.0 wt%. 3. The method for producing a positive electrode plate for a lead storage battery according to claim 1, wherein the boron is contained in the active material by adding a peroxoboric acid compound at the time of preparing the active material paste. .