JPH10162834A - Lead storage battery - Google Patents

Abstract

(57) [Summary] [Problem] It is not possible to eliminate thickness fluctuations of a grating manufactured only by a casting method. For this reason, various types of retainer mats having different thicknesses are prepared at the time of battery assembly, and are used in combination with a retainer mat of an appropriate thickness so as to obtain a good electrode plate compression while measuring the electrode plate thickness. Was.
Since such work is very complicated and the amount of electrolyte that greatly affects battery performance varies, the grid thickness, which is the basis of the electrode plates, must be uniform in order to obtain a battery with even higher performance. Was needed. After forming a grid by a casting method, the grid is pressed to a predetermined thickness within a time determined from a relational expression according to the composition of the lead alloy and the temperature of the atmosphere in which the casting grid is placed, and Is used for at least one of the electrodes.

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 using a lead-calcium alloy lattice.

[0002]

2. Description of the Related Art At present, lead storage batteries are used in various fields including those for automobiles and industries, and there is a strong demand for weight reduction, cost reduction, maintenance free, long life, and stable quality. I have.

[0003] The grid alloy used in lead-acid batteries is lead-
Antimony-based and lead-calcium (-tin) -based alloys can be roughly classified. In particular, in recent years, importance has been placed on maintenance-free characteristics, and lead-calcium-based alloys have come to be used frequently. In addition, the number of sealed lead-acid batteries without fluids is increasing rapidly, especially for stationary and small lead-acid batteries, but most of these sealed lead-acid batteries use lead-calcium (-tin) alloys. I have. This lead-calcium (-
As the composition of the (tin) -based alloy, a calcium content of 0.1 from the viewpoint of mechanical strength, corrosion resistance, charge acceptability after overdischarge, and the like.
In general, those having a tin content of 0.4 to 0.12% by weight and a tin content of 3% by weight or less are often used. About 0.01 to 0.3% by weight of silver, 0.0
Selenium in an amount of about 0.05 to 0.03% by weight may be appropriately added.

On the other hand, most of the sealed lead-acid batteries use a mat-like material made of fine glass fibers having a diameter of about 1 micron as a material for holding the electrolytic solution, that is, a so-called retainer mat. Is also unnecessary, and its handling has become much easier as compared with the conventional open-type lead-acid battery having a fluid. However, since there is no flowing liquid, there is a problem in how to make the contact between the positive electrode plate and the retainer mat or the negative electrode plate and the retainer mat good and promptly proceed the reaction at the time of discharging or charging. That is, the electrode plate group consisting of the positive electrode plate, the negative electrode plate, and the retainer mat inserted between them is pressed uniformly by a certain degree of compression force, and between the positive electrode plate and the retainer mat, and between the negative electrode plate and the retainer mat. It was important that the transfer of the electrolyte to and from the mat proceed quickly without any hindrance.

[0005]

SUMMARY OF THE INVENTION Conventionally, the unevenness of the positive electrode plate and the negative electrode plate, which had a difference of 0.3 to 0.5 mm on one side, was reduced, and the contact between the positive and negative electrode plates and the retainer mat was reduced. In order to improve the shape, the surface shape of the roll press after filling has been changed to one having less unevenness, so that the unevenness difference on one side has been reduced to about 0.25 mm or less. As a result, the contact between the positive and negative electrode plates and the retainer mat has been improved, and the performance has been relatively stable.

However, in many cases, the thickness of the lattice, which is the substrate for filling the paste, fluctuates. Therefore, when a single electrode plate is picked up, the irregularities are considerably reduced.
The electrode plate thickness sometimes fluctuated for each electrode plate lot.
The thickness of the casting grid fluctuates because the thickness of the release agent (water, mixture of water glass and cork powder, bentonite powder, etc.) applied to the mold at the time of grid casting is different each time it is applied, and This is due to the release of the release agent gradually. In order to keep the thickness of the release agent to be applied constant, it is necessary to carry out the application work that was conventionally done manually by a machine, or a release agent mixed with aluminum phosphate so that the applied release agent is hard to peel off Although various methods have been devised, such as the use of a thin film, variations in the thickness of the grating cannot be eliminated. For this reason, at the time of battery assembly, various retainer mats having different thicknesses were prepared, and a retainer mat having an appropriate thickness was used so that a good electrode plate compression was obtained while measuring the thickness of the electrode plate. . Since such work is very complicated and the amount of electrolyte that greatly affects battery performance varies, the grid thickness, which is the basis of the electrode plates, must be uniform in order to obtain a battery with even higher performance. Was needed.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention relates to a method for producing a cast iron within a time required from the ratio of the tin content to the calcium content and the temperature of the atmosphere in which the grid is cast. By pressing the grid after casting, a grid having high corrosion resistance and uniform thickness can be produced.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lead-calcium-tin-based alloy or a lead-calcium-based alloy formed by a casting method. Then, the paste was filled, and a paste-type electrode plate having a difference of unevenness of 0.25 mm or less on one side of the electrode plate was used for at least one of the positive electrode and the negative electrode by a roll press after the filling. In the lead-acid battery, the calcium content of the lattice is 0.04 to 0.12% by weight, the tin content is 3% by weight or less,
(1) The temperature of the atmosphere in which the lattice is placed is 273K
At higher temperatures, if the ratio of tin content to calcium content (Sn / Ca) is less than 9, after casting t ₁ = 7560 / (T-273) ^1.5 t ₁ : time T: cast grid If the ratio of the tin content to the calcium content (Sn / Ca) is 9 or more within t ₁ (time) indicated by the temperature (K) of the atmosphere in which is placed, t ₂ = 15120 / (T-273) ^1.5 t ₂ : time T: temperature (K) of the atmosphere in which the casting grid is placed Within t ₂ (time) indicated by (2) the temperature is 273K
Within 30 days for any alloy in the following cases,
An object of the present invention is to provide an excellent lead storage battery having stable performance by pressing.

[0009]

Embodiment 1 Hereinafter, the present invention will be described based on an embodiment.

First, a grating was prepared. The manufacturing procedure is as follows.

Using a cast iron mold coated with a release agent comprising water glass, cork powder, bentonite powder, aluminum phosphate and water, Pb-0.065% by weight Ca-1.5% by weight Sn-0.007% by weight
Made of% Al, length 100 mm, width 100 mm, thickness 2.
7 mm (target value in the surrounding frame), size of ears width 9
A 15 mm high grid was cast. The mold temperature during casting is 200 ± 10 ° C, and the temperature of the molten lead alloy is 500 ± 10
° C.

Next, the grid was left at room temperature for 1 hour, and then 2.2 mm using a flat plate press heated to about 50 ° C.
Pressed until. The flat plate press used two steel blocks each having a flat surface, a grid was placed between them, and a predetermined thickness was obtained by pressing. The thickness was controlled by placing a 2.2 mm thick sheet of steel outside the grid. Since the lead alloy is considerably softer than the steel sheet, it was possible to control the thickness after pressing with the steel sheet. The lattice was slightly deformed by the flat plate press, but after that, the gate and dumping bar at the time of casting were cut,
Specified dimensions.

For comparison, a grid having the same shape and a target thickness of 2.2 mm was produced by casting with the same alloy composition.

Thereafter, according to a conventional method, a conventional ball mill-type lead powder is kneaded with water and dilute sulfuric acid to prepare a positive electrode paste, and these pastes are formed into a grid which is flat-pressed after the above-mentioned casting and a grid as cast. After filling and pressing with a roll press in which a cotton cloth is wound on a lattice-shaped uneven surface having a difference between the convex portion and the concave portion of 0.3 mm, the difference between the convex portion and the concave portion is 0.05.
The adhesiveness between the grid and the paste was increased by pressing with a roll press in which a cotton cloth was wound around the grid-shaped uneven surface of mm, and the unevenness of the electrode plate surface was reduced to about 0.1 mm or less. Thereafter, aging and drying were performed in a 45 ° C. constant temperature chamber to obtain an unformed positive electrode plate. At the time of filling, the target value of the filling thickness is 2.4 so that the grid surface is covered with the paste.
mm, the paste filling amount was adjusted.

Similarly, Pb-0.065% by weight Ca-0.5% by weight Sn-0.01
100 mm long, 100 mm wide, 1.7 mm thick (surrounding frame), 9 mm wide ears,
After casting a grid having a height of 15 mm, a flat plate was pressed to a thickness of 1.5 mm, and then a negative electrode plate was obtained in the same manner as described above.
BaSO ₄ and lignin were added to the negative electrode plate as commonly used inorganic and organic expanders, respectively.

Table 1 shows the results of measuring the thickness of the as-cast grid and the pressed grid after casting. The thickness was measured at the frame around the grid.

[0017]

[Table 1] As is evident from Table 1, a thickness variation of about 15% was observed between the maximum value and the minimum value only by casting.
In the pressed grid, the difference between the maximum value and the minimum value was remarkably small at about 3%.

Table 2 shows the thickness measurement results of the positive electrode plate after filling. The thickness was measured at the center of the electrode plate.

[0019]

[Table 2] As is apparent from Table 2, the difference between the maximum value and the minimum value reached about 17% in the electrode plate using the as-cast grid, while the maximum value was obtained in the electrode plate using the pressed grid. The difference between the minimum and the minimum value was remarkably small at about 5%.

Regarding the thickness of the negative electrode plate after filling, the same tendency as that of the positive electrode plate was observed.

Next, four and five positive and negative electrode plates were used, and a positive electrode plate was wrapped in a U-shape with a 1.7 mm-thick retainer mat to form an electrode plate group. The battery was inserted into a battery case, and then a sealed battery was formed according to a conventional method. The distance between the electrodes during the production of the electrode group was constant in each case. Table 3 and FIG. 1 show the compression degree and the battery test results when the electrode group was produced. In the battery test, a cycle in which 115% of the discharged electricity was charged with the same current as the discharge current after 5 hR discharge (final voltage 1.70 V / cell) was repeated. The specific gravity of the electrolyte at the start of the test was 1.26 (converted to 20 ° C.), the test temperature was 25 ° C., the number of the produced batteries was 10, each of the 10 test batteries. And three intermediate ones.

[0022]

[Table 3] As is clear from Table 3, in the case of using the pressed grid, the compression degree at the time of preparing the electrode plate group was 25 kgf /
At dm ² , the maximum value was 37 kgf / dm ² , indicating that a stable compression degree was obtained. On the other hand, in the case of using the grid as cast, this time we used a retainer mat with a constant thickness, so the average value is not much different from the one using the pressed grid,
9kgf / dm ² in what degree of pressure is the lowest, is the largest of those has become a 67kgf / dm ^2, and those that are not clever little pressure, a variety of up to things like cause difficulties in insertion pressure is too strong A battery was obtained.

As is clear from the results of the charge / discharge cycle life test shown in FIG. 1, a battery (N
o. No. 1; maximum compression 37 kgf / dm ² , 2;
Nominal compression degree 31 kgf / dm ² , 3; at a compression degree of minimum 25 kgf / dm ² ), the life of each of the batteries was stable at 400 to 450 cycles. On the other hand, in the battery using the as-cast grid, the average compression degree and the maximum compression rate were Battery showing degree (No. 4; maximum compression degree 6)
7 kgf / dm ² , 5: Average compression degree 28kgf
/ Dm ² ), the same life performance as the battery using the pressed grid was shown, but the battery with a small compression degree (No.
6; when the compression degree was minimum 9 kgf / dm ² ), the battery life was about 270 cycles, which was shorter than other batteries.

From the above results, it is apparent that a battery having a very stable cycle life can be obtained by using a grid pressed after casting.

[0025]

Example 2 Next, the relationship between the standing temperature and the standing period until the pressing after the casting and the standing time and the battery performance, particularly the elongation of the positive electrode grid and the corrosion resistance were examined. This is because a lead-calcium-tin-based alloy is a type of alloy in which mechanical strength increases due to the gradual precipitation of intermetallic compounds, and pressing after precipitation is completed has a bad effect on corrosion resistance. This was because there was concern.

Therefore, first, a grating was prepared. The production procedure was the same as in Example 1, but the alloy composition was as shown in Table 4.

[0027]

[Table 4] Next, in the same manner as in Example 1, these lattices were left at the temperature shown in Table 5 for the period shown in Table 6, pressed, and further filled with paste, aged, and dried.

[0028]

[Table 5]

[Table 6] One non-formed positive electrode plate and one normal non-formed negative electrode plate using a grid formed by expanding a rolled sheet on both sides thereof are set in a test cell, and then formed into these test batteries. 3A for 20 hours).

Thereafter, continuous overcharging was performed at 2.0 A for 3 weeks in a 75 ° C. water bath. After the test, the positive electrode plate was taken out of the cell, and the elongation of the lattice and the degree of corrosion were examined.

FIG. 3 (Pb-0.06 wt% Ca-
Judged from the elongation and corrosion state of the positive electrode grid with respect to 1.0% by weight of Sn). .

Such a diagram was prepared for each alloy, and the Sn / Ca ratio (wt% of Sn and Ca) was summarized.
The ratio can be roughly divided into two types. The results are shown in FIG. The curves a and b in the figure correspond to the boundaries between the marks ○ and × in FIG.

The curve a in FIG. 3 shows the result when the Sn / Ca ratio is 9 or more, and the curve b shows the result when the Sn / Ca ratio is less than 9.
The lower left side is an area with little elongation or corrosion.

From these results, it has been clarified that there is a strong relationship between the standing temperature and the standing period until the pressing after the casting, and the battery performance, particularly the elongation of the positive electrode grid and the corrosion resistance. That is, when the Sn / Ca ratio is 9 or more, there is little elongation or corrosion if the temperature and the leaving period are in the lower left region of the curve a in FIG. 3, but the temperature and the leaving period are in the upper right region of the curve a. If so, elongation and corrosion were great. This curve could be approximated by the following equation. t ₂ = 15120 / (T-273) ^1.5 t ₂ : time T: temperature of the atmosphere in which the casting grid is placed (K) Further, when the Sn / Ca ratio is less than 9, the lower left side of the curve b in FIG. Although there was little elongation or corrosion in the region and the standing period in the region, the elongation and corrosion were large in the region in the upper right region of the curve b and the standing period. This curve could be approximated by the following equation. t ₁ = 7560 / (T-273) ^1.5 t ₁ : time T: temperature (K) of the atmosphere in which the casting grid is placed Note that the Ca amount is very small (sample No. 1) and the Ca amount is 0. .12% by weight (sample no.
In 7), the elongation was large and the corrosion was intense regardless of the standing period.

When the storage temperature is lower than 273 K, the storage period is set to 30 days (720 days) regardless of the Sn / Ca ratio.
It is clear that if the time is within (hour), there is no problem with elongation and corrosion of the lattice.

In the above-described embodiment, two steel blocks each having a flat surface are used for the flat plate press, and a lattice is placed between them, and the plate is pressed to have a predetermined thickness.
It is also possible to press with one or more sets of roll presses. If it is a roll press machine, it can be mounted on a casting machine and pressed by a roll press machine installed immediately after casting. However, in this case, if the rolling reduction (thickness after pressing / original thickness) is too small, the deformation of the lattice, particularly the portion parallel to the rotation direction of the roll press, becomes large. ~ 97% is desirable. When the lattice is warped by the roll press, it is desirable to provide a straightening roll.

[0036]

As described above, the lead-acid battery according to the present invention is of high quality and stable without impairing the corrosion resistance, and its industrial value is extremely large. It is.

[Brief description of the drawings]

Fig. 1 Charge / discharge cycle life performance

Fig. 2 Relationship between elongation and corrosion state of positive electrode grid after overcharge test and storage temperature / period (Pb-0.06 wt% Ca-1.0 wt% S
n)

FIG. 3 Relationship between elongation and corrosion state of positive electrode grid after overcharge test, and storage temperature and duration

Claims (5)

[Claims] (1) Lead-calcium produced by a casting method.
A lattice made of a tin-based alloy or a lead-calcium-based alloy,
After casting, after pressing to a predetermined thickness, cut to a predetermined size, and then filled with paste, the roll press after filling, the unevenness on one side of the electrode plate is 0.25 m
m, wherein the calcium content of the lattice is 0.04 to 0.12% by weight and the tin content is 3% by weight or less (1) When the temperature of the atmosphere in which the lattice is placed is higher than 273 K, the ratio of the tin content to the calcium content (Sn / Ca)
Is less than 9, t ₁ = 7560 / (T-273) ^1.5 after casting: t ₁ : time T: temperature (K) of the atmosphere in which the casting grid is placed Within t ₁ (hour) Ratio of tin content to calcium content (Sn / Ca)
Is greater than or equal to 9 after casting: t ₂ = 15120 / (T-273) ^1.5 t ₂ : time T: temperature (K) of the atmosphere in which the casting grid is placed Within t ₂ (time) (2) A lead-acid battery provided with a pressed grid within 30 days for any alloy when the temperature is 273K or lower. 2. The lead-acid battery according to claim 1, wherein the grid is provided with a grid having a thickness of 60 to 97% of the thickness before pressing by a flat plate press. 3. The lead-acid battery according to claim 1, further comprising a grid continuously pressed by a roll press after casting. 4. The lead-acid battery according to claim 1, wherein, after casting, the grid is continuously pressed by a roll press, and then the warped grid is corrected by a straightening roll. 5. The lead-acid battery according to claim 3, wherein the grid is provided with a grid having a thickness of 85 to 97% of the thickness before pressing by a roll press.