JP5909974B2 - Lead acid battery - Google Patents

Description

  The present invention relates to a lead storage battery.

  In lead-acid batteries for trucks, buses, etc., Pb—Sb-based alloys are used for the positive electrode lattice in order to suppress the separation or removal of the positive electrode active material and improve the cycle life characteristics. However, in some vehicle models where the storage battery is placed near the engine, etc., the battery temperature may reach 60 ° C due to the effect of waste heat. It has been found that lead sulfate accumulates early and the life may be shortened by remarkably increasing the liquid speed, increasing the frequency of replenishment, or inhibiting the charge reaction of lead sulfate by the hydrogen generation reaction. Similarly, even in electric vehicle applications that use a clad plate made of a Pb-Sb grid, the temperature of the battery placed in the center of the assembled battery may exceed 70 ° C in summer use. A similar deterioration phenomenon occurs. Note that the Pb—Sb-based positive electrode grid accelerates the decrease of the electrolyte, and is not used when importance is placed on maintenance-free properties.

As a countermeasure against the accumulation of lead sulfate, Patent Document 1 (WO2007 / 036979) states that when Al ³⁺ ions are included in the electrolyte, the charge acceptability of the negative electrode is improved, and lead sulfate can be reduced to metallic lead during charging. . Further, in Patent Document 1, when a Pb—Sb surface layer is provided on the surface of the positive electrode lattice, the adhesion between the positive electrode active material and the lattice can be improved, and when the electrolyte contains Li ⁺ ions, the capacity of the lead storage battery increases. If so.

WO2007 / 036979

  The subject of this invention is improving the lifetime performance in high temperature with respect to the lead storage battery which provided the Pb-Sb type alloy at least in the positive electrode lattice.

The present invention provides a lead-acid battery including an electrolyte composed of a positive electrode grid and a positive electrode active material, a negative electrode grid and a negative electrode active material, and dilute sulfuric acid, at least the positive electrode grid is made of a Pb-Sb alloy, and the electrolyte solution is made of Al. ³⁺ ions are contained in 0.02 mol / L or more and 0.2 mol / L or less, and Li ⁺ ions are contained in 0.02 mol / L or more and 0.2 mol / L or less. Even if only the positive electrode lattice is a Pb—Sb alloy, and both the positive electrode lattice and the negative electrode lattice are Pb—Sb alloys, the light load life performance at high temperatures and the like is improved. In this specification, high temperature means that the temperature of the storage battery is 60 ° C. or higher.

When a lead-acid battery using a Pb-Sb alloy for the positive electrode lattice is used at a high temperature, liquid reduction is promoted due to the Pb-Sb alloy of the lattice, the sulfuric acid concentration of the electrolyte increases, and lead sulfate in the negative electrode active material The sulfation that accumulates easily proceeds. As sulfation progresses, large current discharge becomes difficult and charge acceptability also decreases, resulting in a decrease in life performance, which appears as a decrease in light load life performance at high temperatures. In contrast, if the electrolyte contains Al ³⁺ ions in the range of 0.02 mol / L to 0.2 mol / L and Li ⁺ ions in the range of 0.02 mol / L to 0.2 mol / L, the light load life performance at high temperatures is improved. (FIGS. 1 and 2). At this time, not only the light load life performance at high temperature but also the light load life performance at normal temperature is improved (FIGS. 1 and 2). Light load life performance includes constant voltage charging and large current discharge, and is suitable for evaluating the performance of charge and discharge, which is the basic function of storage batteries. Improving light load life performance generally Leads to improvement.

Even if Al ³⁺ ions are added to the electrolyte at a concentration of 0.02 mol / L or more and 0.2 mol / L or less, as long as the electrolyte does not contain 0.02 mol / L or more and 0.2 mol / L or less of Li ⁺ ions, The improvement in light load life performance is slight (Fig. 2). Even if Li ⁺ ions are added to the electrolyte at a concentration of 0.02 mol / L or more and 0.2 mol / L or less, as long as the electrolyte does not contain 0.02 mol / L or more and 0.2 mol / L or less of Al ³⁺ ions, The improvement in light load life performance is slight (Fig. 1). In other words, the improvement of the light load life performance at a high temperature is a unique phenomenon that occurs in a combination of a specific concentration of Al ³⁺ ions and a specific concentration of Li ⁺ ions.

In order to sufficiently improve the life performance at high temperature, the electrolyte contains both Al ³⁺ ions of 0.02 mol / L or more and 0.2 mol / L or less and Li ⁺ ions of 0.02 mol / L or more and 0.2 mol / L or less. Is necessary (FIGS. 1 and 2). That is, in order to improve the life performance at high temperature, it is necessary that the electrolyte does not simply contain Al ³⁺ ions and Li ⁺ ions, but contains these ions at a specific concentration.

Characteristic diagram showing the dependence of light load life characteristics on Al ³⁺ ion concentration in an electrolyte containing Pb—Sb and Pb—Ca based on the positive electrode lattice and Pb—Ca based on the negative electrode lattice and containing Li ⁺ ions and Al ³⁺ ions. Positive grid is Pb-Sb system, the negative electrode grid Pb-Ca system, in an electrolytic solution containing a Li ⁺ ion and Al ³⁺ ions, characteristic diagram showing the Li ⁺ ion concentration dependency of the light load life characteristics

  Hereinafter, an optimum embodiment of the present invention will be described. In carrying out the present invention, the embodiments can be appropriately changed in accordance with common sense of those skilled in the art and disclosure of prior art.

  Using a Pb-Sb alloy composed of Pb-2mass% Sb-0.2mass% As, a positive grid was fabricated by a casting method. In the Pb-Sb alloy, the Sb concentration is preferably 1 mass% to 4 mass%, the As concentration is preferably 0.1 mass% to 0.4 mass%, and includes other elements such as Sn, Se, Ag, etc. in a total amount of 0.5 mass% or less. The balance is Pb. Using a Pb-Ca alloy sheet made of Pb-0.1mass% Ca-0.7mass% Sn, a negative electrode grid was prepared by the expanding method. In Examples where Pb—Sb alloys were used for both the positive and negative grids, negative grids were prepared by casting using the Pb—Sb alloys.

Synthetic resin fiber was added to lead powder produced by a ball mill method as a positive electrode active material according to a conventional method, pasted with water and dilute sulfuric acid, filled into a positive electrode lattice, aged and dried to obtain an unformed positive electrode plate. Similarly, synthetic resin fiber, BaSO ₄ , lignin and carbon black are added to the lead powder produced by the ball mill method as the negative electrode active material according to a conventional method, and the mixture is pasted with water and dilute sulfuric acid, filled into the negative electrode lattice, aged and dried. To obtain an unformed negative electrode plate. The manufacturing method and manufacturing conditions of lead powder are arbitrary, and the additive to lead powder is also arbitrary.

The unformed negative electrode plate was wrapped with a polyethylene porous separator, and the unformed negative plate and the unformed positive plate were laminated. Next, the ears of the negative electrode plate of the laminate were connected to each other with a strap, and the ears of the positive electrode plate were connected to each other with a strap to obtain an unformed element. Six sets of elements are housed in series in a battery case, water and dilute sulfuric acid containing Al ³⁺ ions and Li ⁺ ions are added, and 145G51 type lead specified in JIS D 5301: 2006 by battery case formation A storage battery was used. Al ³⁺ ions were added as aluminum sulfate and Li ⁺ ions were added as lithium sulfate, but they may be added in the form of LiAlO ₂ , LiOH, Al (OH) ₃ , and the addition form is arbitrary. In addition to dilute sulfuric acid, Al ³⁺ ions, and Li ⁺ ions, the electrolyte solution may contain, for example, 0.02 mol / L or less Na ⁺ ions, K ⁺ ions, Mg ²⁺ ions, and the like. Each battery was fabricated by treating the same material under the same conditions except that the Al ³⁺ ion concentration and the Li ⁺ ion concentration were different. However, there are two types of negative electrode lattices, Pb-Ca alloy and Pb-Sb alloy. In addition, the electrolyte at the time of injection into the battery case is dilute sulfuric acid having a specific gravity of 1.22 at 20 ° C., ignoring Al ³⁺ ions and Li ⁺ ions.

For each combination of Al ³⁺ ion and Li ⁺ ion content in the electrolyte, six lead-acid batteries were produced, and light load life tests specified in JIS D 5301: 2006 9.5.5a) were conducted at 40 ° C and 60 ° C. Three lead-acid batteries were used at different temperatures. According to the JIS regulations, the light load life test is discharged for 4 minutes at 25A and charged for 10 minutes at 14.8V (maximum charging current 25A), 480 cycles every week, and discharged for 30 seconds with CCA current every 480 cycles. The service life is reached when the terminal voltage at the end of discharge is 7.2V or less. The JIS requires that the test be performed at 41 ± 3 ° C. Here, a test at 40 ° C and a test at 60 ° C were performed. The life performance is expressed as a relative value where the number of cycles until the storage battery of the electrolyte solution containing neither Al ³⁺ ions nor Li ⁺ ions reaches the life at 40 ° C. is defined as 100%.

  In a vehicle type in which a lead storage battery is placed near the engine, the temperature of the storage battery may rise to about 60 ° C. Even when not in the vicinity of the engine, the storage battery may be heated up to about 60-70 ° C. depending on the season such as summer, the region, and the driving conditions of the car. In addition, in an electric vehicle using a clad positive electrode plate, the storage battery at the center of the assembled battery may reach a temperature of 70 ° C. or higher in summer. Therefore, in order to evaluate the durability of the storage battery, a test at 40 ° C alone is not sufficient, and a test at a high temperature such as 60 ° C is necessary.

1 and 2 show the main results. In FIG. 1, the Li ⁺ ion concentration was fixed at 0.02 mol / L or 0.2 mol / L, and the Al ^{3 +} ion concentration was varied in the range of 0 to 0.3 mol / L. The result is shown. FIG. 2 shows the results when the Al ³⁺ ion concentration was fixed at 0.02 mol / L or 0.2 mol / L, and the Li ⁺ ion concentration was changed in the range of 0 to 0.3 mol / L. As shown in FIG. 1, when the Al ³⁺ ion concentration is less than 0.02 mol / L, there is a large difference between the life performance at 40 ° C. and the life performance at 60 ° C. On the other hand, when the Al ³⁺ ion concentration is 0.02 mol / L or more and 0.2 mol / L or less, the life performance at high temperature is improved, and the life performance is almost equal at 40 ° C. and 60 ° C. On the other hand, when the Al ³⁺ ion concentration exceeds 0.2 mol / L, the life performance deteriorates at normal temperature and high temperature.

As shown in FIG. 2, when the Li ⁺ ion concentration is less than 0.02 mol / L, there is a large difference between the life performance at 40 ° C. and the life performance at 60 ° C. On the other hand, when the Li ⁺ ion concentration is 0.02 mol / L or more and 0.2 mol / L or less, the life performance at high temperature is improved, and the life performance is almost equal at 40 ° C. and 60 ° C. On the other hand, when the Li ⁺ ion concentration exceeds 0.2 mol / L, the life performance at 60 ° C. decreases.

Table 1 shows the results of each example, from which the following can be understood.
・ Only with electrolytes with both Al ³⁺ ion concentration and Li ⁺ ion concentration of 0.02 mol / L or more and 0.2 mol / L or less, light load life performance at 60 ° C can be increased to 100 or more, and light load at 40 ° C at this time The service life is also increased.
-If either Al ³⁺ ion concentration or Li ⁺ ion concentration is less than 0.02 mol / L, the life performance at 60 ° C cannot be improved.
-If either Al ³⁺ ion concentration or Li ⁺ ion concentration exceeds 0.2 mol / L, the light load life performance at 60 ° C cannot be greatly improved.

  In addition, the light load life performance remarkably decreases at 60 ° C. is a phenomenon peculiar to a storage battery using a Pb—Sb alloy for the positive electrode lattice. For example, Pb-Ca alloys are used in the positive electrode grid in Patent Document 1 and Pb-Sb alloy foils are laminated on the surface. Lead-type batteries with such a battery have a light load life performance at 60 ° C. There was no particular phenomenon that decreased. In the first place, the technology of laminating Pb-Sb alloy foil on the surface of the positive electrode lattice of Pb-Ca alloy has the poor binding force between the lattice and the active material peculiar to Pb-Ca alloy while maintaining maintenance-free properties. It is a technology to improve, and Sb is a small amount. In addition, the technology of laminating Pb-Sb alloy foil on the surface of the Pb-Ca alloy positive electrode lattice has no effect on the corrosion growth of the positive electrode lattice, so vibrations are added and the durability of the lattice is required.・ Pb-Sb alloy positive electrode grids with excellent corrosion resistance and mechanical strength are still used in large vehicles such as buses. The present invention aims to improve the light load life performance at high temperatures in such applications, and a technique for laminating a Pb—Sb alloy foil on the surface of a positive electrode lattice of a Pb—Ca alloy disclosed in Patent Document 1 is a battery. Structure, technical background, and purpose are all different.

In the experiment, by adding an appropriate amount of Al ³⁺ ions to the electrolytic solution, the rate of liquid reduction when using a positive electrode lattice made of a Pb—Sb alloy could be reduced. On the other hand, when Al ³⁺ ions are contained in the electrolytic solution, the conductivity of the electrolytic solution is reduced when discharged with a large current. Further, when Li ⁺ ions were contained in the electrolyte containing Al ³⁺ ions, the conductivity of the electrolyte was restored when discharged with a large current. From these ^facts , the mechanism of improving the light load life performance at 60 ° C. can be estimated as follows when an appropriate amount of Al ³⁺ ions and Li ⁺ ions coexist in the electrolytic solution.
・ With Pb-Sb alloys, electrolyte depletion becomes a problem and dehydration becomes faster at high temperatures.
-When the electrolyte is reduced, the SO ₄ ^2- ion concentration increases, so charge acceptability decreases, PbSO ₄ accumulates, and life performance decreases.
^-If Al ³⁺ ions are contained here, the liquid reduction can be delayed, but the conductivity of the electrolyte decreases, so it becomes difficult to discharge at a large current, and the life performance in the light load life test is not improved.
^-When Al ³⁺ ions and Li ⁺ ions coexist, the conductivity of the electrolyte can be improved and the life performance of a light load life test at high temperature can be improved. However, if the amount of Li ⁺ ions added is too large, the conductivity of the electrolytic solution is lowered. Therefore, it is considered effective that any ion is 0.02 mol / L or more and 0.2 mol / L or less.

The fact that an electrolyte containing both Al ³⁺ ions and Li ⁺ ions in the range of 0.02 mol / L to 0.2 mol / L is effective for Pb-Sb positive electrode lattices is only when the positive electrode plate is a paste type. Absent. Therefore, a clad positive electrode plate using a Pb—Sb alloy may be used. In this case, the negative electrode plate is, for example, a paste type. In the embodiment, the light load life performance at a high temperature can be remarkably improved and the light load life performance at a normal temperature can be improved with respect to a lead storage battery using a positive electrode grid made of a Pb—Sb alloy.

Claims (1)

In a lead storage battery comprising an electrolyte comprising a positive electrode grid and a positive electrode active material, a negative electrode grid and a negative electrode active material, and dilute sulfuric acid,
At least the positive electrode lattice is made of a Pb-Sb alloy,
The lead acid battery, wherein the electrolyte contains Al ³⁺ ions in a range of 0.02 mol / L to 0.2 mol / L and Li ⁺ ions in a range of 0.02 mol / L to 0.2 mol / L.

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