JP2003151618A - Lead-acid battery and additive for lead-acid battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent drop in capacity in charging and discharging of a lead-acid battery, decrease internal resistance, and increase the capacity of the battery. SOLUTION: This lead-acid battery contains indium in an electrolyte and/or an electrode active material mold. An additive for the lead-acid battery contains indium. The additive for the lead-acid battery contains indium and at least one selected from a group comprising polyvinyl alcohol, polyethylene glycol, polyacrylic acid, and lignin.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a lead storage battery having a large electric capacity and having a small decrease in the electric capacity due to repeated charging and discharging, and an additive for a lead storage battery.

[0002]

2. Description of the Related Art Lead-acid batteries have been repeatedly charged and discharged.
When the charge is insufficient, a lead sulfate crystal gradually grows and becomes inactive, so that the amount of the electrode active material decreases and the battery capacity decreases. As a countermeasure to this, there is a method of overcharging for a long time with a small current to convert lead sulfate to metallic lead again, but with this method, only a small portion of the lead sulfate that has been crystal-grown becomes metallic lead, and the effect is poor. . There is also a method of adding various additives such as fine particles of carbon to the electrolytic solution, but fine particles of carbon are easily oxidized by the positive electrode and disappear in a relatively short time, and accordingly the effect disappears. There was a drawback. Further, conventionally, lignin added as an expander for an electrode active material molded body of a lead storage battery has been recognized to have a slight effect of improving battery characteristics, but the effect is slight, and the organic substance generated by electrolytic oxidation at the positive electrode is also small. The acid had side effects such as corrosion of the conductor and was of poor utility. The present inventors have found that polyvinyl alcohol (PVA), polyethylene glycol, polyvinylpyrrolidone, polyacrylic acid, or esters thereof having a specific degree of polymerization in an electrolytic solution of a lead storage battery and / or a positive electrode active material molded body, It was discovered that by adding a linear organic polymer compound having a hydroxyl group in the molecule, the charging efficiency of the negative electrode can be improved and the charge / discharge cycle life can be remarkably extended compared to the conventional case where no addition is made. , Japanese Patent Application 2000
Filed as -169775. However, with these additives, it is necessary to charge for an extremely long time to re-fine the lead sulfate crystals that have grown due to long-term use, which is a practical problem.

[0003]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention The present invention has found an additive for lead-acid batteries that has a much longer life and is cheaper than these conventional methods. A first object of the present invention is to extend the charge / discharge cycle life of a lead storage battery. A second object of the present invention is to increase the capacity of lead acid batteries. A third object of the present invention is to reduce the internal resistance of lead acid batteries. A fourth object of the present invention is to improve the rapid charging performance of lead acid batteries.

[0004]

The present invention provides 1 to 1
A lead storage battery containing 000 ppm of indium in an electrolytic solution and / or an electrode active material molded body, and an additive for lead storage battery containing 2 ppm or more of indium. Further, in the present invention, 0.01 to 5% of polyvinyl alcohol (PVA), 0.01 to 0.
It is desirable to include at least one of the group consisting of 5% polymethyl acrylate and 0.01 to 2% lignin.

[0005]

The present inventors have found that when indium is added to the electrolytic solution or added to the electrode active material, the hydrogen overvoltage in the negative electrode rises during charging, the generation of hydrogen is suppressed, and the charging current is effectively reduced. It has been found to be used for the reduction of lead sulfate. Furthermore, the indium of the present invention and the linear organic polymer compound having a hydroxyl group in the molecule, such as PVA, polyethylene glycol, polyvinylpyrrolidone, polyacrylic acid, or their esters previously invented by the present inventors, are simultaneously prepared. It was found that when used, the reduction of lead sulfate in the negative electrode and the miniaturization of the negative electrode crystal proceed in parallel, and the battery characteristics are recovered in an extremely short time.

Antimony, which is usually added to increase the strength of the positive electrode grid of a lead-acid battery, begins to dissolve in the electrolytic solution during use and precipitates on the negative electrode, reducing the hydrogen overvoltage of the negative electrode and charging the battery. It is known that the generation of hydrogen due to the decomposition of water becomes large and the charging reaction (PbSO ₄ → Pb ⁰ ) becomes difficult to occur. As shown in FIG. 1, in the case of the curve A using the conventional electrolytic solution containing 100 ppm of antimony, current flows from around the negative electrode potential of −0.8 V to generate hydrogen, whereas In the curve B of the present invention to which 200 ppm of ions are added, it can be seen that current does not flow up to around -1.2 V and hydrogen is not generated.

The indium used in the present invention can be used as a compound such as an oxide, a sulfate, a carbonate or an acetate in an electrolytic solution or mixed with an electrode active material, and the amount thereof can be used in the electrolytic solution or the electrode active material. The amount present in the substance is preferably 1 ppm or more. The additive amount to the electrolyte is preferably 2 ppm or more, more preferably 5 to 100.
It is desirable to set it to 0 ppm. PVA can be added to the electrolytic solution as a powder, a tablet, or an aqueous solution, and the amount thereof is preferably 0.01 to 1% with respect to the electrolytic solution. Polyethylene glycol, polyacrylic acid, and lignin are generally added as an aqueous solution to the electrolytic solution, and the amount thereof is preferably 0.01 to 1% with respect to the electrolytic solution. Further, coexistence of PVA, polyethylene glycol, polyacrylic acid, and lignin with respect to indium further promotes miniaturization of the negative electrode active material, which is desirable for recovery of battery characteristics. In addition, as PVA which is effective for refining the metallic lead of the negative electrode, partially saponified PVA in which 70% to 80% is saponified is commercially available, but in this case, an acetic acid group remains in the molecule, and this acetic acid group is 100% saponified PV is used to prevent acrid odors that are released during charging and generate acrid odors.
It is better to use A.

When PVA, polyethylene glycol, polyacrylic acid, lignin and the like are used in combination with indium, they may be added to the electrolytic solution as an aqueous solution or a mixed powder in which they are mixed, or during storage of the mixed aqueous solution. In order to prevent the formation of precipitates, an aqueous solution containing only an indium compound and an aqueous solution such as PVA may be added separately to the electrolytic solution. Further, it is also preferable to add about 0.0001 mol to 0.01 mol of a tin compound, which becomes a crystal nucleus of lead sulfate and is effective for making it finer.

[0009]

【Example】

Example 1 For two lead-acid batteries (48 volts, 350 Ah) for a battery forklift whose working time has deteriorated to about 1/2 (about 4 hours) of a new one after being used every day for 4 years, one of the batteries is In each cell (2 volts), 50% of 5% polypinyl alcohol aqueous solution, stannous sulfate (Sn ⁺⁺ : 10 mg / CC), indium sulfate (In
⁺⁺ : 10 mg / CC of mixed aqueous solution containing 10 CC was added. Nothing was added to the other one for comparison. After using these two forklifts under normal use conditions for 10 days, the specific gravity of the electrolyte of each battery and the working time were compared. The results are shown in Tables 1 and 2. That is, the battery to which In, Sn, and PVA were added showed that the specific gravity of the electrolytic solution increased due to repeated charge and discharge for 10 days, and the sulfation was eliminated, and the working time was close to that of a new battery. Recovered to value.

[0010]

[Example 2] Approximately 30 new ones after being used for 3 years
% Lead-acid battery for trucks (12 volt, 190
Ah), 5 for each cell (2 Volts) of the battery
% Polypinyl alcohol aqueous solution 25CC, stannous sulfate (Sn ⁺⁺ : 10 mg / CC), indium sulfate (I
5 cc of a mixed aqueous solution containing n ^{+ +} : 10 mg / CC) was added. The battery was charged at 8 amps for 16 hours. The characteristics were as shown in Table 3. Since the hydrogen overvoltage of the negative electrode becomes sufficiently high by the addition of indium, the charging was efficiently performed, the sulfation of the negative electrode was quickly eliminated, and the discharge capacity was recovered.

[0011]

EFFECTS OF THE INVENTION As is clear from the above description, the lead-acid battery and the additive for lead-acid battery of the present invention provide a battery having a long battery life with less reduction in battery capacity due to repeated charging and discharging, Particularly, by effectively preventing the generation of hydrogen by antimony, the decomposition of inactive lead sulfate is promoted, and the battery characteristics can be promptly restored.

[Brief description of drawings]

FIG. 1 is a graph comparing the polarization characteristics of a negative electrode of a battery containing the additive of the present invention with that of a conventional product.

[Explanation of symbols]

A, polarization characteristics of the negative electrode in a conventional battery electrolyte containing 100 ppm of antimony B, 100 ppm of antimony and indium 2 of the present invention
Polarization characteristics of negative electrode of battery in electrolyte containing 00ppm

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Claims (3)

[Claims] 1. A lead storage battery comprising 1 to 1000 ppm of indium in an electrolytic solution and / or a molded body of an electrode active material. 2. An additive for a lead storage battery, containing at least 2 ppm of indium. 3. The method according to claim 2, further comprising 0.01 to 5% polyvinyl alcohol, 0.01 to 2% polyethylene glycol, 0.01 to 0.5% polymethyl acrylate, and 0.01 to 2%. % Lead acid additive for at least one of the group consisting of lignin.