JP2006310062A - Lead-acid battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems of a short service life in a lead-acid battery by preventing the stratification of an electrolyte which is caused by a using condition of insufficient charging due to low-voltage charging or frequent idling stops etc. <P>SOLUTION: In this lead-acid battery, SiO<SB>2</SB>and Sb are added to its electrolyte. The SiO<SB>2</SB>addition amount is 0.2-10% by weight per cell to the quantity of electrolytic solution. The Sb addition amount is 7-92 μg/cm<SP>2</SP>per cell to the specific surface area of a cathode plate (the total area of the front and rear surfaces of the electrode plate). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid lead-acid battery for automobiles.

  A liquid lead-acid battery (hereinafter abbreviated as a battery) is a 6-cell configuration (12V nominal) with a 2V single battery in which a positive electrode plate and a negative electrode plate are stacked via a separator, and is used for starting and lighting automobiles. It has been.

  As the battery electrolyte, dilute sulfuric acid diluted with concentrated sulfuric acid is used. Although dilute sulfuric acid is usually stable, when the battery is charged and discharged, moisture and sulfuric acid move between the electrode plate in the battery and the electrolytic solution, and the concentration uniformity cannot be maintained. Specifically, sulfuric acid having a high specific gravity in dilute sulfuric acid moves to the lower part of the cell and moisture having a low specific gravity moves to the upper part of the cell, so that a so-called stratification occurs in which a concentration difference occurs between the upper and lower portions of the electrolyte. When stratification occurs, the charge / discharge reaction hardly occurs in the upper part where the sulfuric acid concentration is low, and the deterioration of the electrode plate (muddying of the active material, corrosion of the lattice) becomes remarkable in the lower part where the sulfuric acid concentration is high.

  As described above, stratification leads to deterioration and short life of the battery, so that the stirring property of the electrolytic solution is improved for the purpose of preventing it. One of the means is to reduce the hydrogen overvoltage of the negative electrode plate, promote the generation of hydrogen gas, and stir the electrolyte by the generation of hydrogen gas to eliminate the stratification of the electrolyte. As a specific example, a method such as Patent Document 1 in which a metal such as Sb (antimony) is added is used to reduce the hydrogen overvoltage. However, when the hydrogen overvoltage is lowered and the generation of hydrogen gas is promoted, the amount of electrolysis of water in the electrolyte increases and the amount of electrolyte decreases. Therefore, there is a problem that the frequency of water replenishment increases and the maintenance-free characteristics are impaired.

JP 2004-207004 A

  As a recent method of using batteries for automobiles, movements such as idling stop have been developed in order to reduce vehicle regulator charging voltage for improving maintenance-free characteristics and to suppress carbon dioxide emission when the vehicle is stopped. Thus, when the state of charge of the battery is low, that is, when it is used in an undercharged environment, the charge / discharge balance is disturbed, and stratification of the electrolyte is likely to occur. In addition, an increase in the number of start-ups due to idling stop places an excessive load on the battery. Therefore, even the method of Patent Document 1 cannot avoid a short life due to stratification under the above-mentioned use environment.

  An object of the battery according to the present invention is to provide a battery having a long life by suppressing stratification due to a decrease in the regulator charging voltage and insufficient charging due to idling stop.

In the present invention, SiO ₂ is added to the electrolytic solution, and Sb is further added, but the amount thereof is reduced as much as possible to suppress stratification of the electrolytic solution.

SiO ₂ imparts viscosity to the electrolyte and lowers fluidity. The movement of sulfuric acid can be prevented by lowering the fluidity. Sb lowers the hydrogen overvoltage, promotes the generation of hydrogen gas, and promotes the stirring of the electrolyte. These synergistic effects suppress stratification due to insufficient charging.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to the following Example at all, In the range which does not change the summary, it can change suitably and can implement.

  Examples of the present invention will be described below.

First, a negative electrode plate is prepared. First, a lattice having an alloy composition of Pb-0.7% Sn-0.04% Ca was produced. Next, 13% by weight of dilute sulfuric acid (specific gravity 1.26: converted to 20 ° C.) with respect to the lead powder and the lead powder and 12% by weight of water with respect to the lead powder were mixed to make a negative electrode active material paste. . After filling the lattice with 75 g of negative electrode active material paste, it was left to mature for 18 hours in a temperature of 50 ° C. and a humidity of 95%, and then left to stand in a temperature of 25 ° C. and a humidity of 40% for 2 hours, and then dried to form an unformed negative electrode I made a board. The apparent area of this electrode plate (total area of the front and back of the electrode plate) is 15.5 cm ² .

  Next, a positive electrode plate is produced. First, a lattice having an alloy composition of Pb-0.8% Sn-0.07% Ca was produced. Next, a positive electrode active material paste was prepared by kneading 10% by weight of dilute sulfuric acid (specific gravity 1.26: converted to 20 ° C.) with respect to the lead powder and 12% by weight of water with respect to the lead powder. . The grid was filled with 95 g of a positive electrode active material paste, and then left to mature for 18 hours at a temperature of 50 ° C. and a humidity of 95%, and then dried to produce an unformed positive electrode plate.

Next, an unformed negative electrode plate was inserted into the bag separator. Eight unformed negative electrode plates and seven unformed positive plate containing the bag separator were laminated. The current collecting portions of the positive electrode plate and the negative electrode plate were welded by a cast on strap method to form an electrode plate group. This electrode plate group becomes a single cell. And after putting each electrode group into the cell chamber in a battery case, 700 ml of electrolyte solution was inject | poured into each cell, and the non-chemical cell was made. The electrolyte is dilute sulfuric acid with a specific gravity of 1.23 (20 ° C. conversion). Subsequently, the unformed battery was formed by applying a direct current of 8 A for 42 hours. After conversion, the specific gravity of the electrolyte was adjusted to 1.28 (converted to 20 ° C.) to produce a battery.
(Comparative Example 1)
A battery in which nothing was added to the electrolyte was defined as an additive-free product.
Example 1
When adjusting the specific gravity after the chemical conversion, colloidal SiO ₂ was added by 2.63% by weight per cell with respect to the amount of the electrolytic solution, gas was generated by charging, and the electrolytic solution was stirred.
(Example 2)
An antimony trioxide (Sb ₂ O ₃ ) was dissolved in 111 μg / cm ² per cell (surface area ratio over the negative electrode plate) and dispersed in the electrolytic solution before the formation.
(Example 3)
A battery was manufactured in which both of Examples 2 and 3 were performed.

  The battery of each example was subjected to the cycle pattern life test shown in FIG. This is a pattern that simulates frequent start-up with low charging voltage and idling stop, and easily induces stratification of the electrolyte.

FIG. 2 shows the life test result of repeating the cycle with the pattern shown in FIG. 1 as one cycle. The object of evaluation was the battery voltage during 100 A discharge related to startability. Since the stratification of the electrolyte occurred as described above, Comparative Example 1 (without addition) reached the life at 6V of the judgment line in about 5000 cycles. On the other hand, when antimony trioxide was added, the battery voltage increased and the life was extended. In addition, SiO ₂ has a slightly lower battery voltage but has a longer life than antimony trioxide. The addition of SiO ₂ and antimony trioxide of Example 3 maintained the state where the voltage was kept high and improved the life characteristics.

The cycle pattern life test shown in FIG. 1 was examined by changing the amount of SiO ₂ added. As shown in FIG. 3, when the SiO ₂ addition amount is 0.2 to 10% by weight, the life performance is improved as compared with the additive-free product. The reason for the decrease when the added amount is larger than 10% by weight is thought to be because the movement of sulfate ions in the electrolytic solution is hindered by the increase in viscosity due to SiO ₂ .

The cycle pattern life test shown in FIG. 1 was examined by changing the amount of antimony trioxide added. As shown in FIG. 4, when the amount of antimony trioxide added was 9 μg / cm ² or more with respect to the apparent surface area of the negative electrode plate, the life performance was improved as compared with the additive-free product. The life number decreases when the addition amount is 111 μg / cm ² or more, which is considered to be an influence of the decrease in the liquid reduction performance due to the addition of Sb. From the molecular weight ratio of antimony trioxide and Sb, Sb is preferably added in an amount of 7 to 92 μg / cm ² with respect to the apparent surface area of the negative electrode plate. The same effect can be obtained with other compounds such as antimony pentoxide and antimony sulfate as the form of addition of Sb.

As described above, in the present invention, by adding SiO ₂ to the electrolytic solution and further adding Sb, stratification of the electrolytic solution can be suppressed, and a long-life battery can be obtained in a use environment where charging is insufficient. .

It is a figure which shows the cycle pattern of a life test. It is a figure which shows the voltage transition of the 100A discharge end stage during a life test. It is a diagram showing the relationship between additive amount of SiO ₂ and cycle life. It is a figure which shows the relationship between antimony trioxide addition amount and cycle life.

Claims (4)

A lead-acid battery for a liquid lead-acid battery for automobiles, wherein the electrolyte contains SiO ₂ and Sb. _2. The lead acid battery according to claim 1, wherein SiO2 is added in an amount of 0.2 to 10% by weight per cell based on the amount of the electrolyte. The lead-acid battery according to claim 1, wherein 7 to 92 µg / cm ^{2 of} Sb is added per cell with respect to the surface area (total area of the front and back surfaces of the electrode plate) over the negative electrode plate.   The lead acid battery according to any one of claims 1 to 3, wherein the lead acid battery is in a use environment that tends to be insufficiently charged and frequently starts.

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