JP2001319681A - Control valve type sealed lead-acid storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealed type lead-acid storage battery that does not increase charge current in floating charge of long-term preservation or the like, and provide a production method that is simple in the structure as far as possible and corresponds to the conventional manufacturing process of batteries. SOLUTION: On the inner wall of a casing contacting with the reaction surface of a cathode plate arranged outside an electrode-group, aqueous solution of a hydrophilic polymer, in which fine silica powder is dispersed, is adhered, the silica layer excellent in liquid-retaining property is stuck and formed on the inner wall of the casing, the oxygen-reduction reaction on the cathode- reaction surface outside the electrode group contacting with the silica layer is restrained, and the closing-reaction efficiency is controlled within a proper range. The silica-mixture solution used in this case shall contain in the mixture liquid 5 weight % or more of fine silica powder with particle size of 100 nm or less, and the hydrophilic polymer to be added shall be a polymer composed of solely carbon, hydrogen and oxygen, and in particular, shall preferably be either of starch, CMC or PVA.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improving the performance of a lead-acid battery of a controlled valve type, and more particularly to extending the life of a lead-acid battery using a floating charge.

[0002]

2. Description of the Related Art A control valve type lead-acid battery is widely used by being incorporated in an uninterruptible power supply. Usually, in order to secure an amount of electricity to be supplied at the time of a power failure, the battery is constantly charged with a minute current under a so-called floating charging condition.

[0003] By the way, under floating charging for a long time, for example, 5
If you continue to use it for more than a year, the charging current will gradually increase,
The power consumption for maintaining the charged state increases, which is uneconomical, and also causes the capacity of the battery to deteriorate. This phenomenon of an increase in the charging current occurs because the efficiency of the so-called sealing reaction, in which oxygen generated by the decomposition of water at the positive electrode in the battery and reduced to water at the negative electrode, becomes unnecessarily high.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned conventional causes, the present invention has been developed to provide a sealed lead-acid battery which does not increase the charging current even in floating charging for long-term storage. It is another object of the present invention to provide a method which is as simple as possible and which is compatible with a conventional battery manufacturing process.

That is, the present invention is to provide a control valve type lead storage battery in which the sealing reaction efficiency is controlled within an appropriate range by a simple method and the life performance is improved, and a method of manufacturing the same.

[0006]

Attention is paid to the fact that silica powder harmless to a lead storage battery has a large liquid retention capacity, and this is combined with a negative electrode plate disposed outside the electrode group structure of a sealed lead battery to form an oxygen powder. The reduction reaction was suppressed. That is, an aqueous solution of a hydrophilic polymer in which fine silica powder is dispersed is adhered to the inner wall of the battery case in contact with the reaction surface of the negative electrode plate disposed outside the electrode group,
Forming a silica layer having a large liquid holding capacity on the inner wall of the battery case, suppressing the oxygen reduction reaction on the negative electrode reaction surface outside the electrode group in contact with the silica layer, and controlling the sealing reaction efficiency to an appropriate range. I do. The silica mixture used in this case is a fine silica powder having an average particle diameter of 100 nm or less, 5 to 12% of the weight of the mixture, and the hydrophilic polymer to be added is carbon,
It is a polymer composed of only hydrogen and oxygen, particularly preferably starch, CMC (carboxymethylcellulo-
) And PVA (polyvinyl alcohol). Further, the present invention is characterized in that, in order to form the silica layer, the silica mixture is applied or sprayed on the inner wall of the battery case to a thickness of 150 μm or more in a dry state, and then the battery case is dried. I do.

The oxygen reduction reaction on the negative electrode plate does not occur at a uniform rate, but largely depends on the amount of electrolyte on the negative electrode surface and the ease of diffusion of oxygen. As a result of the experiment, the oxygen reduction reaction was remarkable on the outer surface of the negative electrode plate outside the electrode group when the floating charging current increased. The reason is that this part does not contact the electrolyte retainer, the force for holding the electrolyte is smaller than other parts of the negative electrode plate, and there is a slight dimensional difference in the thickness direction of the electrode group above and below the battery case. In particular, a gap is easily formed above the pole group, and oxygen is easily circulated in the gap.

Therefore, if this surface is constantly covered with the electrolyte, the speed of the sealing phenomenon can be controlled. As a means, a layer of fine silica powder is previously formed on the inner wall of the battery case, and the silica layer is filled with a gap where oxygen of the negative electrode plate in contact with the inner wall of the battery case is diffused,
In addition, the sealing reaction can be controlled in order to apply the electrolytic solution to the outer surface of the negative electrode.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below.

FIG. 1 is a sectional view of a main part of the battery of the present invention.
A negative electrode plate 1 and a positive electrode plate 2 are separated by a separator 3 to form a pole group, and a silica layer is formed without any gap on the inner wall of a battery case 4 where the working surface of the negative electrode plate 1 arranged outside the pole group contacts. 5 is attached.

Next, regarding the characteristics of the silica layer of the present invention,
The following tests were performed. First, conditions to be possessed by an aqueous solution of a hydrophilic polymer in which fine silica powder is dispersed and embodiments thereof will be described. (Example 1) The primary particle diameter of silica powder was changed, and the effect was examined. In order to make the evaluation method similar to the state after performing floating charging for a long period of time, the amount of the electrolyte injected into the battery cell was reduced by 7% from the usual amount, and an acceleration test was performed in an environment at a temperature of 55 ° C. Table 1 shows the results. When the silica addition ratio was the same, the expected performance improvement was realized as the primary particle diameter was smaller. This is because the smaller the primary particle diameter is, the stronger the bond between the silica particles is, and the larger the specific surface area of the silica particles is, the larger the liquid retention power is. As a result of the test, when the primary particle diameter was 100 nm or less on average, substantially stable results were obtained.

[0012]

[Table 1]

(Example 2) Next, fine silica powder having a primary particle diameter considered appropriate was added to the hydrophilic polymer aqueous solution in several ratios. Table 2 shows the results of evaluation of the prototype battery manufactured in this manner under the same conditions as in Example 1.
When the particle diameter is constant, the higher the silica addition rate, the higher the performance. However, if the addition rate is high, the viscosity of the silica mixture becomes high, and the work becomes difficult. In particular, when spraying, the ejection port of the liquid tends to be clogged with silica, which may significantly reduce the workability. From the viewpoint of suppressing the charging current, a stable effect can be expected if the added amount of silica is 5% or more. However, from the viewpoint of workability, it is desirable to suppress the amount to 12% or less.

[0014]

[Table 2]

Example 3 The thickness of the amount of silica formed from the silica mixture is an important factor along with the fine silica particle diameter and the amount of silica added. In order to determine this appropriate value, a prototype battery in which the thickness of the silica layer formed by applying or spraying on the inner wall of the battery case was changed was evaluated under the same conditions as in Example 1. Table 3 shows the results. Table 3 shows that the effect of suppressing the charging current is remarkable at a thickness of 150 μm or more. When the silica layer is further thickened, the current does not decrease anymore, while the silica layer may be peeled off when inserting the electrode group in the battery case, and the beneficial effect is not seen even if it is made thicker than necessary. .
The upper limit of the thickness does not need to be greater than the thickness required to fill the gap between the inner wall of the battery case and the outer surface of the electrode group, and may be determined for each battery.

[0016]

[Table 3]

(Example 4) When selecting a hydrophilic polymer, the fine silica powder is kept in a layered state in a dry state, and the liquid retaining power of silica is not impaired, and the battery performance in the battery is adversely affected. Is a condition that does not produce a substance that causes For this purpose, it is safe to select a polymer consisting only of carbon, hydrogen and oxygen. In this example, starch, CMC,
Three types of PVA were picked up, and the optimum value of each added amount was investigated. In the experiment under the same conditions as in Example 1, the effect of increasing the current appeared when the amount of PVA added exceeded 2.5%, and the internal resistance of the battery was significantly increased, thereby shortening the battery life. FIG. 2 is a curve showing the effect of PVA on the transition of the charging current during floating charging. The vertical axis represents the charging current (100 on the 240th day of the conventional product), and the horizontal axis represents the floating charging date. , Table 4 are shown. FIG. 3 is a curve showing the effect of PVA on the internal resistance during floating charging. The vertical axis shows the internal resistance (100 on day 240 of the conventional product), and the horizontal axis shows the floating charging date. ing.

This is presumably because a substance having a carboxylic group was formed in the process of oxidizing the dissolved PVA at the positive electrode. The charge current of other polymers also tended to increase with time in the region where the addition rate was high, but if the starch was 8% or less and the CMC was 5.5% or less, there was no significant effect on the battery life. Was.

[0019]

[Table 4]

(Embodiment 5) Based on the above results, the battery N
o. A and No. C was subjected to a 40 ° C. floating charge, and charge current and capacity measurements were continued for three years. FIG. 4 shows the results.
FIG. 4 shows the charge current and discharge capacity ratio (240
The measured value on the day is taken as 100), and the horizontal axis represents the floating charging period (month), showing a comparison curve of the characteristic performance of the battery. In the battery C of the present invention, the increase in the charging current is suppressed. Also, the discharge capacity was constant and stable, and a remarkable improvement in life was observed.

Next, an embodiment of the method for producing the battery of the present invention will be described.

As shown in the enlarged view of the silica mixed liquid sprayer in FIG. 5, the nozzle end of the silica mixed liquid thin tube 6 is slightly moved close to the distal end nozzle of the pressurized gas thin tube 7 whose end is bent in an L shape. On the rear side, the mixed liquid is vigorously sprayed with a pressurized gas for application. The silica mixed solution is applied or sprayed on the inner wall of the battery case in advance. In the actual process, for example, as shown in FIG. 6, several tips of thin nozzles are inserted into the battery case 4 and moved while moving. The method of spraying the mixed solution from the thin tube 6 is convenient for adjusting the thickness of the silica layer and efficiently processing. After spraying the silica mixture, the silica layer is fixed on the inner wall of the battery case through a drying furnace. The effect of the present invention can be expected if there is a layer having a thickness of 150 μm or more between the inner wall of the battery case and the negative electrode plate outside the electrode group.

In the above step, the silica mixture must have a fluidity that does not hinder the spraying step. The silica composition is 12% or less, and the hydrophilic polymer is, for example, 6% in the case of starch.
The following is preferred. After the formation of the silica layer, the battery is manufactured by inserting the electrode group in the usual manner.

[0024]

As described above, claim 1 of the present invention is provided.
Is formed on the inner wall of the battery case in contact with the reaction surface of the negative electrode plate disposed outside the electrode group. The reduction reaction is suppressed, the sealing reaction efficiency can be controlled in an appropriate range, and the charging current in floating charging is reduced to 1/3 of that of the conventional product.
It can be suppressed to the extent. Therefore, it is possible to provide a control valve type lead storage battery having excellent life performance.

According to the second aspect, the layer of fine silica particles has an excellent liquid retaining ability, and the charging current can be suppressed for a long period of time. Therefore, the effect of claim 1 can be remarkably achieved.

According to the third aspect, the charging current is suppressed, the life performance is excellent, and the workability in forming a layer of fine silica particles is excellent.

Furthermore, according to claim 4, the effect of claim 1 is excellent.

According to the fifth aspect, the effect of the first aspect can be sufficiently exhibited.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing an embodiment of the present invention.

FIG. 2 is a graph showing an influence of PVA on a charging current in one example of the present invention.

FIG. 3 is a graph showing the effect of PVA on the internal resistance during charging in one example of the present invention.

FIG. 4 is a graph comparing the charge current and the discharge capacity of the product of the present invention and the conventional product.

FIG. 5 is an enlarged view of a main part of the silica mixed liquid sprayer according to the present invention.

FIG. 6 is an explanatory view showing a manufacturing method of the present invention.

[Explanation of symbols]

 Reference Signs List 1 negative electrode plate 2 positive electrode plate 4 battery case 5 layer of fine silica particles

Claims (5)

[Claims] 1. A control valve type lead-acid battery in which a negative electrode plate is disposed outside a group of electrodes, wherein a layer of fine silica particles is attached and formed on an inner wall of a battery case where a reaction surface of the negative electrode plate contacts. Control valve type sealed lead-acid battery. 2. A control valve-type sealed lead-acid battery according to claim 1, wherein the fine silica particles have a primary particle diameter of 100 nm or less on average. 3. A layer of fine silica particles according to claim 1 or 2, wherein the layer of fine silica particles is added to an aqueous solution to which a hydrophilic polymer is added in an amount of 5 to 12%.
A sealed valve-type lead-acid storage battery characterized by being formed by adhering a mixed solution to which fine silica particles of weight% are added. 4. A control valve-type sealed lead-acid battery according to claim 3, wherein the hydrophilic polymer is a polymer composed of only carbon, hydrogen and oxygen. 5. The sealed lead-acid storage battery according to claim 1, wherein the layer of the fine silica particles is 150 μm or more in a dry state.