JPH0636792A - Sealed lead-acid battery - Google Patents

Abstract

(57) [Summary] [Object] To provide a sealed lead-acid battery which is easy to manufacture and has stable and constant characteristics. A sealed lead-acid battery using granular powder as an electrolyte holder, wherein the powder is mixed with thermally expandable microcapsules.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art There are two types of sealed lead-acid batteries of the retainer type and the gel type, in which the negative electrode absorbs oxygen gas generated during charging of the battery. The retainer type inserts a mat-shaped separator (glass separator) mainly composed of fine glass fibers between the positive electrode plate and the negative electrode plate, which holds the sulfuric acid electrolyte necessary for discharge and separates 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 no maintenance, no leakage, and position-free.

However, the glass separator is made of a fine glass fiber having a diameter of about 1 micron, which is manufactured by a special method, into a mat, and is considerably expensive as compared with a commonly used separator for a lead storage battery. Also, in order to obtain stable battery performance, it is necessary to strongly squeeze and incorporate the electrode plate group, which makes it difficult to assemble the battery and inevitably increases the manufacturing cost of the battery.

Further, the sulfuric acid electrolyte can be held only by the positive and negative electrode plates and the glass separator inserted between the positive and negative electrode plates. Since the electrolytic solution cannot be placed in the surroundings, the battery reaction is limited by the amount of the electrolytic solution, 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 that of the retainer type sealed lead acid battery,
There is a drawback that the life performance is not good because the electrolyte separates from the sulfuric acid gel during use.

In order to solve these drawbacks, therefore, 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, for example, a silica powder, is used as the electrolytic solution holder, and the above 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 with a configuration.
Silica powder is an inexpensive material that is mass produced and sold, and because it has excellent acid resistance and electrolyte retention, it is an excellent powder for use in the electrolyte retainer of this type of sealed lead-acid battery. It can be said that it is a material.

However, in a sealed lead-acid battery using this powder as an electrolytic solution holder, the powder moves to the upper part of the battery along with the electrolytic solution and the generated gas discharged from the electrode plate during charging, and the positive electrode plate and the negative electrode. A gap may be formed between the plate and the plate, and the battery performance may be deteriorated.

Therefore, in order to suppress the movement of the powder, for example, a thin porous sheet is placed on top of the powder, and a perforated resin plate having a plurality of holes is further placed in the battery case. The silica powder was fixed by inserting or by foaming a phenol resin on the upper part of the powder. However, the method of using a thin porous sheet and a perforated resin plate together is complicated, and there is a drawback that the perforated resin plate is required to have high dimensional accuracy because it is forcibly inserted into the battery case.

When a synthetic resin is foamed in situ to fill the space inside the battery with open-cell plastic foam to fix the powder, a film called a skin layer is always formed on the surface of the plastic foam to prevent gas and gas. Since the permeation of the liquid is significantly hindered, the powder filled in the battery cannot communicate with the outside, so that the injection of the electrolytic solution is impossible and the battery cannot be constructed.

[0010]

The present invention fills a gap between a positive electrode plate and a negative electrode plate and a periphery of an electrode plate with powder having a high porosity and a large specific surface area, and is necessary for charging and discharging a battery. The problem of the sealed lead-acid battery in which a sufficient amount of the sulfuric acid electrolytic solution is substantially impregnated and held in the powder and the electrode plate group, that is, the powder is generated together with the electrolytic solution and the generated gas discharged from the electrode plate during charging. It prevents the deterioration of the battery performance by moving to the upper part of the battery and causing a gap between the positive electrode plate and the negative electrode plate. The gist of this is to fill the mixed powder of the powder and the heat-expandable microcapsule. It is characterized by that.

[0011]

EXAMPLES The present invention will be described below based on examples.
FIG. 1 is a schematic view showing an embodiment in which the sealed lead acid battery according to the present invention is applied to a battery for automobiles. In the figure, the positive electrode plate 1 is a positive electrode plate in which a grid made of an antimony-free lead alloy or a lead alloy containing a small amount of antimony is filled with a positive electrode paste. As an antimony-free lead alloy, calcium Ca 0.05 to 0.12 wt%, tin Sn 0.20 to 1.0
A general lead calcium alloy containing wt% can be used.
Depending on the battery application, the Sn content should be 1.5-5.0 wt%.
In order to stabilize the Ca content during casting and aluminum, it is possible to add about 0.001 to 0.02 wt% of aluminum Al.

The antimony Sb content of the lead-antimony-based alloy is Sb 0.7 to 2.0 wt%, especially 0.7 to 1.5 wt%
Arsenic As is 0.1 as the metal other than antimony.
Add ~ 0.3 wt%. Note that 0.01 to 0.5 wt% Sn is added to improve the chargeability after deep discharge, and selenium Se, sulfur S, copper Cu, etc. are added to improve castability and corrosion resistance.
It is also effective to add about 0.003 to 0.03 wt%.

As the positive electrode paste to be filled in the positive electrode grid, a general paste prepared by kneading lead powder with dilute sulfuric acid can be used, but in order to improve the chemical conversion property of the positive electrode plate and the battery performance, It is preferable to mix lead tin (Pb ₃ O ₄ ) in the lead powder.

The negative electrode plate 2 is manufactured by filling a normal negative electrode paste obtained by adding an expander such as lignin or barium sulfate to a lattice made of an antimony-free lead alloy. The lead alloy of the negative electrode grid is Ca 0.05 to 0.12 wt%, Sn 0 to 0.
A general lead calcium-based alloy containing 7 wt% and Al 0 to 0.02 wt% can be used.

As the above-mentioned positive and negative electrode grids, any of cast ones, expanded grids obtained by expanding a lead alloy sheet, punched grids and the like can be used. The electrode plate filled with the paste should be aged in a room at 30 to 50 ° C before use. Aging of the positive electrode plate is particularly important for battery performance.

Reference numeral 3 is a synthetic separator inserted between the positive electrode plate and the negative electrode plate. Any separator having a small thickness and porosity and low electric resistance can be used, but a separator having an excessively small pore size is not preferable because oxygen gas hardly permeates and the oxygen absorption reaction by the negative electrode is hindered.

Further, in order to fill the powder between the positive and negative electrode plates, it is necessary to provide a gap between the both electrode plates, and for that purpose, a corrugated separator, an embossed separator or the like is provided with irregularities on the surface. It is convenient to use separate separators. If powder described later is used as the electrolytic solution holder, the powder layer between the electrodes also has a function as a separator, and in such a case, the use of the separator can be omitted.

The positive electrode plate, the negative electrode plate, and the separator described above are stacked, and the positive and negative electrode plates are separately welded to produce an electrode plate group, which is inserted into the battery case 4. In the one using the conventional glass separator, it was very difficult to insert into the battery case because the electrode plate group had to be strongly pressed, but in the present invention it is not necessary to press the electrode plate group so that the insertion is not possible. It's easy.
After inserting the electrode group into the battery case, the cells are connected. In the figure, 5 is a strap, 6 is an inter-cell connecting portion, and 7 is a pole.

Next, the battery case lid 8 is welded to the battery case 4. Here, the battery case lid 8 is provided with an exhaust chamber 9 and a powder filling port 10, an exhaust valve 12 is disposed above the exhaust chamber 9, and an air-permeable porous plate 13 is disposed below the exhaust valve 12. There is. The exhaust valve 12 has a function of opening when the internal pressure of the battery rises and closing when reducing the internal pressure of the battery, and any generally used valve such as a cap valve, a ring valve and a plate valve can be used.

The porous plate 13 is for releasing gas generated during charging of the battery, initial charging, or charging during use to the outside, and allows gas and liquid to pass through, but does not pass powder. It is made of an acid-resistant open-cell porous body having pores of a size, for example, a sintered body of foamed phenol or alumina.

If the lower end of the perforated plate 13 is arranged close to the upper end of the electrode plate group, it is possible to shorten the liquid injection time when the electrolytic solution is injected prior to the initial charging. That is, when the porous plate is brought close to the upper end of the electrode plate group, the injected electrolytic solution is first absorbed by the electrode plate and spreads to the surroundings, so that the liquid injection time can be significantly shortened.

After assembling the lead-acid battery having the above structure, a fixed amount of a mixed powder 14 of powder and heat-expandable microcapsules is supplied from the filling port 10, and the positive and negative electrode plates and the negative electrode plate are fed while vibrating the battery. Fill around the electrode group.

When a monoblock battery composed of a plurality of cells is filled with powder, it is convenient to make the filling amount constant so that the powder can be easily filled and the liquid injection amount can be made constant. However, in general, the inner volume of the battery case and the volume of the space behind the battery container lid are slightly different for each cell, so that the filling amount is not constant when the powder is filled in the battery container. Further, along with that, it is necessary to adjust the liquid injection amount according to the powder filling amount, which complicates the work. However, when a certain amount of powder is filled in each cell, a space is inevitably formed in the upper part of the battery. If a space is created in the battery, the powder moves during the liquid injection or the initial charge, and a cavity is created in the powder layer filled between the electrode plates, so that the expected battery performance cannot be obtained.

As described above, when a certain amount of the mixed powder 14 is filled, a space remains behind the lid in the upper part of the battery, and the volume of the space varies from cell to cell. However, since the thermally expandable microcapsules are used, the mixed powder 1 containing the microcapsules in which the space is thermally expanded even if the space volume is slightly different.
4 can be filled, and the entire mixed powder 14 can be fixed.

It should be noted that the powder as the electrolytic solution holder is preferably one having a high porosity in the filled state, an acid resistance and an excellent electrolytic solution absorbing power and a high fluidity. Primary particle size is 10-40 millimicrons, specific surface area 150-200 m
A granular powder was used in which fine particles of ² / g hydrous silicon dioxide (SiO ₂ .n H ₂ O) were aggregated to form secondary particles of 50 to 200 microns. This powder has excellent fluidity,
Gravity acceleration of 2 to 4 G, amplitude of 1 to 2 m for filling powder in the battery case
If vibration of about m is applied, it can be filled densely in a short time, and it can also be filled without any gaps on the uneven surface on the back side of the battery case lid.
In addition, the powder after filling is 90% comparable to glass separators.
It has a close porosity.

After filling the mixed powder 14, the powder filling port 10
Is sealed with a sealing plug 11, and then the microcapsules are expanded by heating, and the space created between the mixed powder and the lid back is filled with the mixed powder 14 to fix the entire mixed powder.

As the heat-expandable microcapsules, low-boiling hydrocarbons are microencapsulated with a shell wall of a copolymer such as vinylidene chloride or acrylonitrile, and unexpanded particles having a diameter of 10 to 30 microns are used. Can be used. These shell walls are 80-150 ° C depending on the material used.
It softens at a maximum expansion ratio of 20 to 70 times.

The proportion of the heat-expandable microcapsules in the mixed powder can be changed depending on the case, the shape of the back of the case lid, the configuration of the electrode plate group, etc., but is usually 15% or less (volume ratio). ) Is preferred. This is because if the mixing ratio of the heat-expandable microcapsules is too large, the amount of electrolytic solution that can be held in the electrode plate group will decrease, and the battery capacity will decrease.

When the battery thus assembled is initially charged, the exhaust valve 12 is first removed and a predetermined amount of sulfuric acid electrolytic solution is injected. The injected electrolytic solution passes through the perforated plate 13, passes through the mixed powder below it, and is absorbed by the positive and negative electrode plates, the separator, and the mixed powder around it. When the lower end of the porous plate 13 is provided close to the upper end of the electrode plate group as described above, the liquid injection is completed in a shorter time. The initial charging is performed with the exhaust valve 12 attached. Although the electrolyte surface rises due to gassing during charging, the electrolyte surface is trapped in the exhaust chamber 9, so that the electrolyte solution does not leak to the outside even if an overflow prevention jig is not mounted as in the conventional case.

Next, the results of the initial performance test and the life test of the sealed lead acid battery according to the present invention will be described.
The battery used in the test is a 12V sealed lead-acid battery for automobiles.
The nominal capacity is 25Ah. Table 1 shows the test results. In addition,
The life test was performed under the following conditions. Constant voltage life test conditions:
Temperature 75 ℃ Discharge 25A for 4 minutes Charge 14.8V for 10 minutes (maximum current 25A)

[0031]

[Table 1]

A is a mixture of granular hydrous silicon dioxide 90% (volume ratio) and heat-expandable microcapsules 10% (volume ratio) as a mixed powder, and Pb-0.1 wt% Ca-0.7 wt% Sn is used for the positive electrode.
It is a product of the present invention using a cast lattice made of -0.007 wt% Al alloy. B is a retainer type conventional product using the same positive electrode grid as A. Each negative electrode was an expanded lattice using a rolled sheet of Pb-0.07 wt% Ca-0.5 wt% Sn alloy. As is clear from this experimental example, the initial performance is 5 hour rate capacity, 15
The invented product A was slightly superior to the conventional product B in terms of 0 A discharge capacity. It is considered that this is because the amount of the electrolytic solution of the product of the present invention could be kept a little larger than that of the conventional product. But,
The characteristic of the product of the present invention lies in the life test result.

In the life test, the above-mentioned charging / discharging is taken as one cycle, and the cold cranking current (274 A) is taken every 500 cycles.
Was discharged, and the life was defined as the time when the voltage dropped to 7.2 V at 30 seconds. As a result, the life of the battery A of the present invention is the same as that of the conventional battery B.
This is an improvement of about 60% compared to that of the above, and a life of 3,150 cycles was obtained in a high temperature atmosphere of 75 ° C.
Further, it was found that the amount of the electrolyte solution decreased during the life test was small and the sealing reaction efficiency was excellent.

When the battery is disassembled and observed after the life test,
In a sealed lead-acid battery using a conventional glass separator, the positive electrode grid was significantly corroded, and the positive electrode plate had deteriorated to the extent that it could not retain its original shape. Since it is fixed, the deformation was slight. It is considered that this is also one of the reasons why the product of the present invention has excellent life performance.

Further, in the conventional battery B, a part of the negative electrode strap was corroded, but in the battery A of the present invention, such corrosion was not observed. This is because the conventional retainer-type sealed lead-acid battery has the exposed strap portion of the electrode plate group, whereas the sealed lead-acid battery according to the present invention has the entire electrode plate group buried in the powder layer. I think that the. The fact that corrosion does not occur even under such harsh use conditions is one of the great advantages in terms of safety.

Further, since it is not necessary to press the electrode plate group, the assembling of the battery is easy, and the materials used are inexpensive, so that the manufacturing cost of the battery can be greatly reduced. Also,
If the powder and the heat-expandable microcapsules are mixed in advance, a special process for fixing the powder at the time of battery production, for example, placing a thin porous sheet on top of the powder, The step of forcibly inserting the perforated resin plate having a plurality of holes into the battery case is unnecessary, which is also effective in reducing the manufacturing cost.

In the above embodiment, only the mixed powder having a constant mixing ratio was filled from the beginning, but the mixed powder having a small mixing ratio of the thermal expansion microcapsules was mainly used between the positive and negative electrode plates to expand the thermal expansion microcapsules. It is also possible to fill the electrode plate group with mixed powder having a large mixing ratio of capsules. In this way, the mixed powder can be fixed even if the space volume behind the lid of the battery case varies more greatly.

Further, for example, if the present invention is applied to a tubular lead-acid battery, a sealed lead-acid battery can be easily manufactured. Traditionally, tubular lead-acid batteries are
Since the positive electrode plate is not flat, it is not possible to use a glass separator. Therefore, only a gel type sealed lead acid battery can be manufactured, which has a serious shortcoming that the life is short.

However, it has been found that the production of the battery according to the present invention not only simplifies the production of the battery, but also provides a sealed tubular lead-acid battery with excellent life performance.

[0040]

As described in detail above, the sealed lead-acid battery of the present invention does not need to change the powder filling amount or the liquid injection amount according to the variation in the battery cell inner volume for each cell, and the fixed amount of The powder is filled, the amount of liquid injected is constant, and the remaining space in the upper part of the battery expands and fills the thermally expandable microcapsules mixed in the powder. It is possible to obtain a stable battery with stable characteristics, which is easy to manufacture and has a great industrial value.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of the sealed lead acid battery of the present invention.

[Explanation of symbols]

 1 Positive electrode plate 2 Negative electrode plate 3 Separator 4 Battery case 5 Strap 6 Cell connection part 7 Electrode column 8 Battery case lid 9 Exhaust chamber 10 Powder filling port 11 Sealing plug 12 Exhaust valve 13 Porous plate 14 Mixed powder

Claims (1)

[Claims] 1. A gap between the positive electrode plate and the negative electrode plate and the periphery of the electrode plate group are filled with powder having a high porosity and a large specific surface area, and a sufficient amount of sulfuric acid electrolyte necessary for charging and discharging the battery is provided. What is claimed is: 1. A sealed lead acid battery in which the powder and an electrode plate group are substantially impregnated and held, wherein the powder is mixed with thermally expandable microcapsules.