JPH08264202A - Lead acid battery - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a lead-acid battery that prevents a short circuit inside the battery without lowering the battery performance and is excellent in cost. [Configuration] A lead storage battery comprising a positive / negative electrode plate, a separator, and an electrolytic solution, wherein an intersection point of a grid, which is a current collector of either the positive / negative electrode plate, and another electrode plate current collector. A lead-acid battery characterized in that it is located at a position that does not face the grid or cross points of the lattice.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in lead acid batteries.

[0002]

2. Description of the Related Art Lead acid batteries have come to be widely used as a backup power source for portable devices and computers, a power source for starting and lighting automobiles, and an electric vehicle, and there is a strong demand for improvement in their performance. Has become.

Looking at a lead-acid battery for starting and lighting an automobile, the distance between the positive and negative electrode plates is reduced and the resistance of the separator is reduced in order to achieve a higher starting performance. When the distance between the positive and negative electrode plates is reduced, the amount of the electrolytic solution is substantially reduced, that is, the amount of the electrolytic solution per active material of the battery is also reduced.

In a battery with a small distance between the electrode plates and a small amount of electrolyte, if left for a long time or over-discharged, sulfate radicals in the electrolyte are consumed and the electrolyte becomes close to water. . In such a state, dendritic lead may grow from the negative electrode plate toward the positive electrode plate during charging of the battery, causing a short circuit between the positive and negative electrode plates.

In recent years, batteries that are maintenance-free, liquid-free, position-free, etc. have been desired, and as a battery satisfying these requirements, a sealed type of a type in which the negative electrode absorbs oxygen gas generated from the positive electrode during charging. Lead acid batteries have been developed and are commonly used. This type of battery includes a so-called retainer type battery. This is to insert a separator (glass separator) mainly composed of fine glass fibers having a diameter of about 1 μm between the positive electrode plate and the negative electrode plate, thereby holding the sulfuric acid electrolyte necessary for discharging and separating the two electrodes. .

[0006] However, this type of sealed lead-acid battery is designed so that it does not contain a fluid in order to make it leak-free,
The amount of the electrolytic solution was smaller than that of a normal open type lead acid battery, and there was a tendency that the above-described short circuit occurred inside the battery.

As a method of preventing a short circuit inside the battery after being left unattended, the lattice bone is not exposed at the central portion of the surface of the positive electrode plate (Japanese Patent Laid-Open Publication No. 60-148059).
No.) or a sulfate of a metal having a redox potential lower than that of lead, for example, Li ₂ SO ₄ or CdSO ₄ is added to the electrolytic solution or the active material (Japanese Patent Laid-Open Publication No. 52-85336).
Etc. have been proposed.

Thus, when an alkali metal or a substance having a redox potential less than that of lead is added to the electrolytic solution or the active material,
Although it has been known for a long time that a short circuit inside a battery can be prevented, if the amount of addition is too large, there is a possibility that the battery manufacturing cost may increase and the battery capacity may decrease when discharged at a high current.

The present invention solves the above-mentioned problem of internal short circuit which tends to occur in an open type battery having a small distance between the positive and negative electrode plates and a small amount of electrolyte and a sealed lead acid battery having a small amount of electrolyte. is there.

[0010]

The present invention is directed to a positive / negative electrode plate,
In a lead-acid battery composed of a separator and an electrolytic solution, the crossing point of the grid body that is the current collector of either the positive or negative electrode plate is the cross point or crossing point of the grid body that is the current collector of the other plate. It is in a position not facing each other, preferably a so-called expanded lattice in which at least one of the positive and negative electrode plate current collectors is developed with a lead sheet, and more preferably the distance between the positive and negative electrode plates is 1 mm or less, and It is characterized in that sodium sulfate is added to the electrolytic solution.

By doing so, it is possible to provide a lead-acid battery that prevents a short circuit inside the battery without lowering the battery performance and is excellent in cost.

[0012]

EXAMPLES The details of the present invention will be described below with reference to examples.

A temporary specific gravity of about 1.8 containing PbO of about 75% by weight.
A positive electrode paste for a lead storage battery was obtained by kneading 100 kg of g / cm ³ lead powder with diluted sulfuric acid having a specific gravity of about 1.15 at a ratio of about 25 liters. Lead oxide may be added to the positive electrode paste for the purpose of improving chemical conversion efficiency, or synthetic fiber having a length of about 2 to 5 mm may be added for improving the strength of the electrode plate. An appropriate amount of synthetic fiber added is about 0.1 to 0.3%.

This was filled in various kinds of lead-alloy grids shown in FIG. 1 and aged and dried to obtain a positive electrode plate. The grids used in this example are a cast grid (a, b, c) and an expanded grid (d, e) made of Pb-0.07 wt% Ca-0.5 wt% Sn alloy. The grid used for the positive electrode may be any of Pb-Ca (-Sn) alloys and Pb-Sb alloys that are generally used in lead-acid batteries.

The negative electrode paste is prepared by kneading 100 kg of lead powder containing about 75% by weight of PbO having a temporary specific gravity of about 1.8 g / cm ³ with diluted sulfuric acid having a specific gravity of about 1.15 at a ratio of about 20 liters. Using. Additives such as barium sulfate and lignin are added to the negative electrode paste to prevent the active material from shrinking during repeated charging and discharging, and synthetic fibers are added to improve the mechanical strength of the active material. Or
Carbon may be added in order to improve the chemical conversion.

This negative electrode paste was filled in the same grid as the positive electrode grid described above, and was aged and dried to obtain a negative electrode plate. As the negative electrode grid alloy, similarly to the positive electrode plate, various alloys generally used in lead acid batteries can be used.

By combining the positive and negative electrode plates using these grids, an open lead storage battery and a sealed lead storage battery were manufactured according to a conventional method. FIG. 2 shows an example of a conventional lattice combination, and FIG. 3 shows an example of a lattice combination according to the present invention. In the figure, the positive grid is shown as a solid line and the negative grid is shown as a dotted line.

FIGS. 2 (1), 2 (2) and 3 (3) are conventional combinations in which the positive and negative electrode plates have the same grid shape, and are shown in FIGS. 1 (a), 1 (b) and 2 (e), respectively. It uses a grid in the shape of a box. 2 (4) is a positive electrode shown in FIG.
It is a conventional combination using the cast lattice of (a) and the expanded lattice of (e) for the negative electrode.

2 (1) and 2 (3), the positive electrode grid and the negative electrode grid are overlapped with each other, and the intersections 4 of the grids 3 of the grid are located at positions facing the positive and negative electrode plates. In FIG. 2 (2), the intersection points 4 of the lattice do not overlap each other, but the negative electrode rod 3 is located at a position facing the intersection point 4 of the positive electrode lattice. Figure 2 (4) shows
The positive electrode grid 3 is located at a position facing the intersection point 4 in the central portion of the negative grid.

As described above, in the conventional combination, the pole 3 or the crossing point 4 of the other electrode plate is located at the position opposite to the crossing point 4 of the grid rod 3 of either one of the positive and negative electrodes.

FIGS. 3 (1), 3 (2) and 3 (3) show examples of combinations according to the present invention, in which the positive electrode plate and the negative electrode plate are opposite to the intersection point 4 of the lattice board 3 of the other plate. It is a combination without poles 3 and cross points 4 of the electrode plate. FIG.
(1) is a combination using the casting grid of FIG. 1 (a) for the positive electrode and the casting grid of (b) for the negative electrode. 3 (2) and 3 (3) are examples of combinations in which the former uses the cast lattice of (c) for the positive electrode, the expanded lattice of (e) for the negative electrode, and the latter uses the expanded lattice of (d) for both the positive and negative electrodes. .

The open type battery using the combination of these positive and negative electrode plates has a diameter of about 10 to 2 as a separator for the positive and negative electrode plates.
A glass mat made of 0 μm glass fiber and a separator made of paper made of silica powder, glass fiber, resin fiber and the like were stuck together. For sealed batteries,
A mat mainly composed of fine glass fibers having a diameter of about 1 μm was used as a separator.

In both the open type and the closed type, positive and negative electrode plates and separators are alternately laminated according to a standard method, placed in a battery case, filled with liquid, and subjected to chemical formation. An automobile battery with a discharge capacity of 24 Ah · 12 V was manufactured. The specific gravity of sulfuric acid after chemical formation was set to 1.28 at 20 ° C. for an open battery and 1.30 for a sealed battery.

In these batteries, the distance between the positive and negative electrode plates is 0.
5 mm and 1 mm were prepared. In addition, an electrolyte solution was prepared by adding 5 g of sodium sulfate per 1 liter of the electrolyte solution and a solution without addition thereof. When adding sodium sulfate, it was added to the electrolyte in the form of sulfate,
It need not be a sulfate and may be a hydroxide or carbonate as long as it is not harmful to the battery. The same effect can be expected with lithium and potassium, but it is considered that the use of sodium is most suitable in view of the cost of additives.

The batteries produced are shown in Table 1. In addition, these batteries were manufactured in both an open type and a closed type. Table 1
In addition, the conventional products shown in FIGS. 2 (2), (3) and (4)
The battery using the combination of FIG.
A battery using the combination of (2) and (3) was also manufactured at the same time.

[0026]

[Table 1]

Using these open-type and closed-type lead-acid batteries, which correspond to 5 hR under an electrolyte temperature of 25 ± 1 ° C.
It was discharged at a current of 8A. Then, connect a resistor of 10 Ω between the positive and negative terminals in the discharged state, let stand for 28 days at a temperature of 40 ± 2 ° C (in a water bath), and then charge at a constant current. The cells were discharged at a current of 0.8 A to a discharge end voltage of 1.75 V per cell, and the discharge duration time was examined. This was repeated until the 4.8 A discharge duration became half of the initial time.

FIG. 4 shows the test results of the open type battery.
The batteries C, D, and E, which are the products of the present invention, all exhibited a performance of 5 cycles or more, while the batteries A and B, which were the conventional products, had a low discharge performance of 2 cycles and 1 cycle, respectively. The batteries were disassembled and the cause of the decreased capacity was investigated. In the batteries C, D and E which are the products of the present invention, the positive electrode active material was slightly deteriorated, and no short circuit was observed in the separator in appearance. On the other hand, in the conventional batteries A and B, dendritic lead grown from the negative electrode was found in the separator, and the short circuit between the positive and negative electrode plates due to this dendritic lead was the cause of the capacity decrease. Further, the short-circuited portion was at a position where the crossing point 4 was opposite to the crossing point 3 or the crossing point 4 of the other electrode plate.

Battery D in which the distance between the positive and negative plates was 0.5 mm
Comparing the discharge durations of the fifth cycle with those of E and E, the battery E containing sodium sulfate was excellent, although it was slight. As a result of the disassembly examination, no difference was observed between the positive and negative electrode plates and the separator, but it was considered that an extremely slight short circuit occurred in the battery D due to the difference in discharge duration.

The distance between the positive and negative electrode plates was 1 mm using the conventional combination shown in FIGS. 2 (2), (3) and (4).
The batteries having the sizes of 0.5 mm and 0.5 mm showed the same results as the batteries A and B, respectively. Further, the batteries having the distances between the positive and negative electrode plates of 1 mm and 0.5 mm using the combination of the present invention shown in FIGS. 3B and 3C also showed the same results as the batteries C and D, respectively.

If the battery is left for a long period of time or is over-discharged, the sulfate radicals in the electrolytic solution are consumed and the electrolytic solution becomes close to water. In such a state, dendritic lead is likely to grow from the negative electrode plate to the positive electrode plate during charging of the battery, which may cause a short circuit between the positive and negative electrode plates. The cause of such a short circuit is not clear, but it is considered as follows. First, as the amount of sulfate in the electrolytic solution decreases, the solubility of lead increases and a large amount of lead begins to dissolve in the electrolytic solution. When charging is started, sulfate radicals are released from the positive and negative electrode plates into the electrolytic solution. Since the charging of the positive and negative electrodes starts from the vicinity of the grid of the grid 3, the concentration of the sulfate group near the grid of the grid 3, especially near the crossing point 4, rises sharply at the same time as the charging starts, and the solubility of lead increases rapidly. Decrease to. At this time, it is considered that the dissolved lead is precipitated as lead sulfate in the vicinity of the lattice 3 and the crossing points 4, and the precipitated lead causes a short circuit between the positive and negative electrode plates.

When the distance between the positive and negative plates is large, the above-mentioned problem does not occur due to the diffusion of sulfate and lead. However, as the distance between the positive and negative plates becomes smaller, the pole 3 or the other plate of the other plate is placed at a position opposite to the intersection point 4 of the lattice plate 3 of one of the positive and negative plates as in the conventional example. In the battery with the crossing point 4, such a phenomenon occurs from both positive and negative electrodes,
I think that it will easily lead to a short circuit.

It should be noted that the intersection 4'of the frame 2 of the lattice and the sleeve 3 '
Did not seem to have a short circuit. This is the frame 2
In the vicinity, it is considered that the open-type battery was in contact with a large amount of electrolytic solution.

The sealed battery produced in the same manner has the same tendency as that of the open battery, and the product of the present invention has 3 to 3 times the conventional product.
It was excellent for more than 5 cycles. Further, in the conventional product, as in the case of the open type battery, a short circuit is caused at a position where the crossing point 4 and the electrode 3 of the other electrode plate or the crossing point 4 face each other.
The intersection 4 ′ between the frame 2 and the shell 3 of the lattice did not seem to be related to the short circuit. This is because, even in the sealed battery, since the glass separator is usually larger than the electrode plate, a large amount of the electrolytic solution is held therein, and the electrolytic solution diffuses quickly in the vicinity of the frame 2 and the short circuit does not occur. It is considered to be a thing.

It seems that the shorter the distance between the positive and negative plates is, the larger the short circuit portion is, and the greater the effect of the present invention is. Considering the battery volume efficiency, the distance between the electrodes is preferably 1 mm or less, and the addition of sodium sulfate to the electrolytic solution seems to further enhance the effect of preventing a short circuit.

Further, the cost is reduced by using the expanded lattice on at least one of the positive and negative electrode plates.
When expanded grids are used for both the positive and negative electrodes, the same shape of grid can be used as shown in FIG. 3C for the combination example, and the cost can be further reduced.

In the present embodiment, lead powder containing about 75% by weight of PbO was used to prepare the positive and negative electrode pastes. However, it is possible to use lead powder containing 60 to 80% by weight of PbO which is usually used in lead acid batteries. it can.

As described above in detail, in a lead-acid battery comprising a positive / negative electrode plate, a separator, and an electrolyte solution, the intersection point of the grid, which is the collector of either the positive / negative electrode plate, is the other. At a position that does not face the cross or crossing point of the grid body which is the electrode plate current collector, preferably, at least one of the positive and negative electrode current collectors is a so-called expanded grid formed by expanding a lead sheet, More preferably, the distance between the positive electrode plate and the negative electrode plate is 1 mm or less, and sodium sulfate is added to the electrolytic solution to prevent short circuit inside the battery without lowering battery performance. In addition, it was possible to provide a lead storage battery that is excellent in cost, does not deteriorate the battery performance, and can improve the volume efficiency of the lead storage battery.

[0039]

As described above, according to the present invention, it is possible to provide a lead-acid battery which prevents a short circuit inside the battery due to charging after being left for a long period of time, is excellent in cost, and does not deteriorate the low-rate high-rate battery performance. In addition, the volumetric efficiency of the lead storage battery can be improved, and its industrial value is enormous.

[Brief description of drawings]

FIG. 1 is a diagram showing examples of various lattice shapes.

FIG. 2 is a diagram showing an example of combination of various lattices of a conventional example.

FIG. 3 is a diagram showing an example of combination of various lattices according to the present invention.

FIG. 4 is a diagram showing changes in battery capacity during a life test.

[Explanation of symbols]

 1 Lattice collector ear 2 Lattice frame body 3 Lattice board 4 Lattice intersection point (intersection point between lattice bar 3 and lattice bar 3) 4'Lattice intersection point (intersection point between lattice frame body 2 and lattice bar 3) 5 Lattice Supporting feet

Claims (3)

[Claims] 1. A lead storage battery comprising a positive / negative electrode plate, a separator, and an electrolytic solution, wherein an intersection point of a grid, which is a current collector of either the positive / negative electrode plate, and another electrode plate collection. A lead-acid battery characterized in that it is located at a position where the grid or the crossing point of the electric body does not face each other. 2. The lead storage battery according to claim 1, wherein at least one of the positive and negative electrode plate current collectors is a so-called expanded grid formed by developing a lead sheet. 3. The lead acid battery according to claim 2, wherein the distance between the positive electrode plate and the negative electrode plate is 1 mm or less, and sodium sulfate is added to the electrolytic solution.