JP3261417B2 - Sealed lead-acid battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a sealed lead-acid battery.

[0002]

2. Description of the Related Art There are two types of sealed lead-acid batteries of the type in which oxygen gas generated during charging of a battery is absorbed by a negative electrode, a retainer type and a gel type. In the retainer type, a mat-like separator (glass separator) mainly composed of fine glass fiber is inserted between the positive electrode plate and the negative electrode plate, thereby holding the sulfuric acid electrolyte required for discharge and isolating both electrodes. In recent years, it has been widely used as a backup power source for portable devices and computers, taking advantage of its features such as maintenance-free, liquid-free, and position-free.

[0003] However, the glass separator is made by forming a fine glass fiber having a diameter of about 1 micron manufactured by a special method into a mat shape, and is considerably more expensive than a commonly used separator for a lead storage battery. In addition, in order to obtain stable battery performance, the electrode plate group must be strongly pressed and assembled, so that it is difficult to assemble the battery, and the manufacturing cost of the battery is inevitably increased.

[0004] Further, only the glass separator inserted between the positive and negative electrode plates can hold the sulfuric acid electrolytic solution, and the electrolytic solution is applied around the electrode plate group like an open type liquid lead storage battery. Since the battery cannot be arranged, the battery reaction is limited by the amount of the electrolyte, and the battery performance is inferior to that of the liquid battery.

On the other hand, the gel type is less expensive than the retainer type, but the battery performance is inferior to the retainer type sealed lead-acid battery,
There was a drawback that the life performance was not good because the electrolyte solution separated from the sulfuric acid gel during use.

In order to solve these drawbacks, there has been proposed a sealed lead-acid battery which is neither a retainer type using fine glass fibers nor a gel type using a gel electrolyte. That is, a powder having a high porosity and a large specific surface area, such as silica powder, is used as an electrolyte holding material, and the powder is filled in the gap between the positive electrode plate and the negative electrode plate and around the electrode plate group. It is a sealed lead-acid battery of the configuration.
Silica powder is an inexpensive material that is mass-produced and sold, and has excellent acid resistance and electrolyte retention ability, making it an excellent powder for use as an electrolyte retention material in this type of sealed lead-acid battery. It can be said that it is a material.

However, even when the above-mentioned method is used, sufficient cycle performance cannot be exhibited in the case of a so-called heavy duty use, in which the depth of discharge represented by a battery for a battery forklift is large and the battery tends to be high in temperature. There was a drawback that the life was extended.

[0008]

According to the present invention, there is provided a sealed lead-acid battery comprising: a silica powder having a particle size of 50 to 300 μm in a gap between the positive electrode plate and the negative electrode plate and around the electrode plate group; After filling, a sealed lead-acid battery, in which a sufficient amount of sulfuric acid electrolyte is substantially impregnated and held in the powder and the electrode group for charging and discharging of the battery, between the positive and negative electrodes. A separator having an average pore diameter of 0.5 μm or more is provided.

[0009]

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

FIG. 3 is a sectional view of a main part showing the structure of the sealed lead-acid battery of the present invention. An electrode plate group 2 composed of a clad type positive electrode plate, a negative electrode plate and a separator is inserted into a battery case 1. The gap between the positive electrode plate and the negative electrode plate and the separator and the periphery of the electrode plate group are filled with the powder 3 having high porosity and large surface area. Since the powder 3 has a high porosity and a large surface area, the powder 3 can hold a large amount and strong electrolyte. In this example, silica powder was used.

The silica powder used here has a specific surface area of 200
m ² / g, silicon oxide content 94% (anhydride equivalent), Al ₂
O ₃ : 0.2%, Fe ₂ O ₃ : 0.02%, Na ₂ SO ₄ : 1.
3% of commercially available white carbon is granulated using water glass and classified so that 90% or more of the total weight has a particle size of 50 to 300 μm.

A pedestal 4 composed of a perforated plate 5 and an exhaust valve 6 is placed on top of the powder 3. The pedestal 4 has an exhaust port at the top, and an exhaust valve is mounted on the exhaust port. In this embodiment, a ring-shaped rubber valve is used. A perforated plate is attached to the lower part of the pedestal, and the perforated plate 5 and the pedestal 4 are bonded to each other without any gap, and gas or electrolyte enters the space 8 formed by the pedestal and the perforated plate. Powder does not enter. Here, a foamed phenol resin plate was used as the perforated plate. Also, the resin liquid 7 is filled around the pedestal.
After curing, the pedestal was fixed, the silica powder was fixed, and the battery was hermetically sealed.

With the battery having the above-described structure, a battery test was performed using a separator prepared and manufactured by changing the mixing ratio of silica powder, polyester fiber, and glass fiber. Various separators having a thickness of 0.5 mm and an average pore diameter of 0.045 to 20.5 μm were tested. The separator was disposed almost in the middle between the positive and negative electrode plates. The used separator and battery No. Is shown in Table 1.

[0014]

[Table 1]

The battery was a sealed lead-acid battery with a nominal capacity of 250 Ah, and the amount of electrolyte was a positive / negative electrode active material, a tube, a separator and 9% of pores of silica powder.
It was set to be 6%. These batteries are heated to a temperature of 50
° C, discharge 50A × 3h, charge 50A × 2.5h + 20A
It was subjected to a cycle life test of × 2.5 h. 1 and 2 show the results of the life test. FIG. 1 shows the transition of the capacity during the life test, and FIG. 2 shows the relationship between the average pore diameter of the separator used and the cycle life performance.

As is clear from FIGS. 1 and 2, the larger the average pore diameter of the separator, the better the life performance. In particular, when the average pore size was 0.5 μm or more, all exhibited excellent life performance.

In this embodiment, the upper limit of the average pore diameter of the separator was not determined, but if it is too large, dendritic crystals of lead grow from the negative electrode plate into the separator and penetrate therethrough.
Since it may cause a short circuit by contact with the positive electrode plate,
The upper limit is about μm.

The value of the average pore diameter used here is a value calculated by the mercury intrusion method as D (average pore diameter) = 4 × V (pore volume) / A (specific surface area). Further, here, a paper-made separator of silica powder and fiber was used, but a separator such as a sintered body of PVC powder or an extrusion-type separator mainly composed of silica powder and synthetic resin was used. A similar trend was observed.

In general, in the case of a liquid lead storage battery or a closed lead storage battery, when the thickness of the separator is constant, the smaller the average pore diameter of the separator is, the higher the electric resistance is slightly. There is a tendency to become. However, in this example, unlike the above, there was a tendency that the life performance was improved as the average pore diameter was larger.

Although the cause is not clear, when the average pore size is large, the oxygen gas generated from the positive electrode plate during overcharging moves to the negative electrode plate more quickly, so that the sealed reaction efficiency is excellent and the electrolyte solution during the cycle is excellent. It may be because the rise in specific gravity could be suppressed. Furthermore, since the amount of electrolyte in these batteries is slightly depleted, the electrolyte tends to be held in a small pore size, and a positive electrode having a relatively large pore size has a larger average pore size of the separator. In addition, a large amount of the electrolytic solution may be retained in the negative electrode active material, so that the discharge capacity may be relatively large even after the lapse of the charge and discharge cycle.

[0021]

As described above in detail, the sealed lead-acid battery of the present invention has a great industrial value, for example, the cycle life performance at the time of deep discharge, which is a conventional drawback, can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change in capacity during a life test.

FIG. 2 is a diagram showing a relationship between an average pore diameter of a separator and cycle life performance.

FIG. 3 is a sectional view of a main part showing an embodiment of the sealed lead-acid battery of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery case 2 Electrode group 3 Silica powder 4 Pedestal 5 Perforated plate 6 Exhaust valve 7 Resin 8 Space

Claims (1)

(57) [Claims] 1. The method according to claim 1, wherein a gap between the positive electrode plate and the negative electrode plate and around the electrode plate group
90% or more of the total weight is a particle having a particle size of 50 to 300 μm.
A sealed lead-acid battery comprising a sulfuric acid electrolytic solution, which is necessary and sufficient for charging and discharging the battery after filling the powder and substantially impregnating and holding the powder and the electrode plate group. A sealed lead-acid battery, wherein a separator having an average pore diameter of 0.5 μm or more is arranged between plates.