JP2006196283A - Lead-acid battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lead-acid battery of a long service life by suppressing deterioration of a positive electrode plate due to corrosion of a positive electrode lattice in the lead-acid battery provided with the positive electrode lattice of Pb-Ca-Sn alloy. <P>SOLUTION: In the lead-acid battery provided with the positive electrode lattice of the Pb-Ca-Sn alloy, this Pb-Ca-Sn alloy contains Al of the containing concentration of 0.001 wt% to 0.03 wt%, and also contains Se of the containing concentration of 0.001 wt% to 0.05 wt%. Then, more preferably, an expanding lattice obtained by expanding processing a rolled body of this Pb-Ca-Sn alloy is used as the positive electrode lattice. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to lead-acid batteries, and in particular to positive grids.

  Conventionally, a positive electrode grid alloy for a lead-acid battery is a Pb—Sb-based alloy to which 2.5 mass% to 8.0 mass% of Sb is added for the purpose of improving the mechanical strength and corrosion resistance of the grid. Has been. However, since Sb contained in the alloy moves to the negative electrode and the hydrogen overvoltage of the negative electrode decreases, the self-discharge of the battery is likely to proceed, and the electrolysis of water is promoted in an overcharged state. The water loss becomes remarkable.

  Therefore, such lead storage batteries require maintenance such as periodically recharging or replenishing the electrolyte with water.

  In order to reduce the maintenance required for such a lead storage battery, as the positive electrode lattice alloy, Sb is limited to 0.0001% by mass or less, and by suppressing the hydrogen overvoltage drop of the negative electrode caused by Sb, In particular, a Pb alloy containing no Sb is used.

  A Pb—Ca—Sn alloy is well known as a Pb alloy not containing Sb. Ca in such an alloy contributes to the mechanical strength of the alloy, and Sb contributes to an improvement in corrosion resistance together with the mechanical strength of the alloy.

  In the Pb—Ca—Sn alloy used for this positive electrode lattice, if the Ca content concentration is less than 0.03 mass%, the mechanical strength of the positive electrode lattice is insufficient, and if it exceeds 0.10 mass%, Pb Since the corrosion resistance of the alloy is lowered, the Ca content concentration is generally 0.03% to 0.10% by mass.

  Further, in the Pb—Ca—Sn alloy described above, when the Sn content concentration is less than 1.0 mass%, the corrosion resistance particularly required for the positive electrode lattice cannot be sufficiently ensured. Moreover, when exceeding 2.2 mass%, a different subject generate | occur | produces with the manufacturing method of a positive electrode grid. For example, when a positive electrode grid is produced by a casting method, crystal grain boundaries become prominent, and corrosion resistance against intergranular corrosion decreases. Moreover, when producing a positive electrode grid by the expanding method, the elongation of the alloy is reduced, so that there is a problem that the grid is easily broken. Therefore, the Sn content concentration in the Pb—Ca—Sn alloy is generally in the range of 1.0 mass% to 2.2 mass%.

As an example of an alloy composition containing Ca and Sn at the above-described concentration, for example, Patent Document 1 discloses a Pb-0.05 mass Ca-1.3 mass% Sn alloy.
Japanese Patent Laid-Open No. 7-14583

  However, lead-acid batteries for vehicles, in particular, are in an environment in which positive grid corrosion is likely to occur due to the influence of heat released from the engine by being used in a position adjacent to the engine in the vehicle. In addition, such a vehicle lead-acid battery is also required to be small and light. And even when it is reduced in size and weight, in order to maintain the output characteristics and discharge capacity, the concentration of sulfuric acid in the electrolytic solution is increased by using a thinner grid.

  These have the effect of increasing the voltage at the time of discharge and increasing the discharge duration, but the corrosion of the positive grid is further promoted and the current collection of the positive grid itself is reduced or deformed due to corrosion. There was a problem that the positive electrode grid was short-circuited with the negative electrode, resulting in a short life.

  It is an object of the present invention to obtain a lead storage battery that suppresses the corrosion that proceeds in the positive electrode grid of such a lead storage battery and has a long life and excellent reliability.

  In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention is a lead storage battery including a positive electrode lattice body made of a Pb—Ca—Sn alloy, and the Pb—Ca—Sn alloy is 0.001 mass. The lead acid battery is characterized by containing Al in an amount of 0.0% to 0.03% by mass and containing Se in an amount of 0.001% to 0.05% by mass.

  Addition of Se to the Pb-Ca-Sn alloy is not effective in improving corrosion resistance and strength with Se alone, but is added together with Al, and the concentration of Se and Al is set to the above concentration. As a result, Se is uniformly dispersed in the positive electrode lattice body, the corrosion resistance of the positive electrode lattice body is remarkably improved, and the life of the lead storage battery is improved.

  Moreover, the invention according to claim 2 of the present invention is the lead-acid battery according to claim 1, wherein the positive electrode lattice is an expanded lattice obtained by expanding the rolled body of the Pb—Ca—Sn alloy. Is.

  In particular, when the Se distribution is non-uniform, non-uniformity in the alloy strength occurs, and cracks are locally generated during the expansion process. According to the present invention, the Se distribution is made uniform and the alloy strength is homogenized, so that the generation of local cracks during the expansion process can be suppressed.

  The above-described lead storage battery according to the configuration of the present invention suppresses the corrosion of the positive electrode grid body, thereby suppressing a decrease in current collection efficiency and an internal short circuit caused by the corrosion and obtaining a long-life lead storage battery.

  Hereinafter, the structure of the lead acid battery by embodiment of this invention is demonstrated.

  The lead acid battery of this invention is equipped with the positive electrode grid body of a Pb-Ca-Sn alloy. This Pb—Ca—Sn alloy contains 0.001% by mass to 0.03% by mass of Al and 0.001% by mass to 0.05% by mass of Se.

  In addition, as Ca content density | concentration in this Pb-Ca-Sn alloy, if Ca content density | concentration is less than 0.03 mass%, it is inadequate in terms of the mechanical strength of a positive electrode grid, and exceeds 0.10 mass%. In this case, since the corrosion resistance of the Pb alloy is reduced, the Ca content concentration is suitably 0.03% by mass to 0.10% by mass.

In addition, when the Sn concentration is less than 1.0% by mass, the corrosion resistance particularly required in the positive electrode lattice cannot be sufficiently ensured. Moreover, when it exceeds 2.2 mass%, when producing a positive electrode lattice body by a casting method, a crystal grain boundary becomes remarkable and the corrosion resistance with respect to intergranular corrosion falls. Similarly, when a positive electrode grid is prepared by the expanding method when the Sn content concentration exceeds 2.2% by mass, the lattice tends to be broken due to a decrease in the elongation of the alloy. Therefore, it is appropriate to select the Sn content concentration in the Pb—Ca—Sn alloy in the range of 1.0 mass% to 2.2 mass%.

  Using such a positive electrode lattice body obtained from a Pb—Ca—Sn alloy containing 0.001% by mass to 0.03% by mass of Al and containing 0.001% by mass to 0.05% by mass of Se. In the subsequent steps, the lead storage battery of the present invention can be obtained by configuring the lead storage battery according to a conventional method.

  As the positive electrode grid, a cast grid may be used. However, the use of the expanded grid obtained by subjecting a rolled product obtained by rolling a positive grid alloy to an expanded process is longer in the present invention. Since an effect can be acquired more notably, it is more preferable.

  The Ca content concentration in the Pb-Ca-Sn-Al-Se alloy is 0.04 mass% and 0.1 mass%, the Sn content concentration is 1.0 mass% and 2.2 mass%, and the Al content concentration is 0 mass%. %, 0.0005% by mass, 0.001% by mass, 0.01% by mass, 0.03% by mass and 0.05% by mass, and the Se-containing concentration is 0% by mass, 0.0005% by mass, 0.001% by mass. %, 0.05% by mass and 0.10% by mass, and positive electrode lattice alloys with the balance being Pb were prepared. The compositions of these positive electrode lattice alloys are shown in Table 1, Table 2, Table 3, and Table 4.

  Using the alloys having the respective compositions shown in Tables 1 to 4, cast lattice bodies and expanded lattice bodies were prepared. The cast grid was prepared by pouring into a mold of a book mold type and cooling and solidifying. The expanded lattice body is obtained by subjecting a rolled sheet obtained by stepwise rolling a cast slab having a thickness of 10.0 mm obtained by melting and cooling and solidifying each alloy to a thickness of 1.0 mm. It was.

  The cast lattice body and the expanded lattice body prepared from each of the positive electrode lattice alloys described above were filled with the same amount of positive electrode active material paste and aged and dried to obtain an unformed positive electrode plate.

  For the negative electrode plate, a rolled sheet obtained by gradually rolling a cast slab (thickness 10.0 mm) of Pb-0.07 mass% Ca-0.25 mass% Sn alloy to a thickness of 0.6 mm is expanded. The expanded lattice produced in this manner was filled with a negative electrode active material paste and aged and dried to obtain an unformed negative electrode plate.

As the separator, a polyethylene sheet having micropores in a bag shape was used. In order to provide micropores, the separator used was a separator containing porous silica, paraffinic mineral oil and carbon for improving acid resistance. In this example, the content concentration of porous silica was 60% by mass of the total mass of the separator, and the mineral oil was 15% by mass of the total mass of the separator.

  A negative electrode plate was accommodated in this bag-shaped separator, a lead storage battery was assembled in combination with the positive electrode plate, a dilute sulfuric acid electrolyte solution was injected, and charge formation was performed to prepare a 2V55Ah liquid lead storage battery.

  About these lead acid batteries, the life test was performed on the following conditions, respectively, and the life characteristic was evaluated.

Life test conditions (in gas phase at 75 ° C)
(1) Discharge 25A constant current, 4 minutes (2) Charge 2.45V constant voltage (limit current 25A), 10 minutes (3) Determination discharge every 480 cycles of the discharge-charge cycle of (1) and (2) above . Judgment Discharge at 582A constant current for 5 seconds. Life judgment voltage 1.2V
In the life test, the judgment discharge (3) is performed every 480 cycles (1) to (2). The life ends when the voltage at the 5th second during the judgment discharge is 1.2 V or less. When the voltage at the 5th second exceeded 1.2 V, the charge of (2) was performed, the cycle of (1)-(2) was repeated for 480 cycles, and the operation of performing the judgment discharge of (3) was repeated. . The life test results are shown in Table 1, Table 2, Table 3, and Table 4 described above.

  Table 1 shows cast lattice bodies prepared by using positive electrode lattice alloys A1 to A30 in which the Al content concentration and the Se content concentration are changed in a Pb alloy having a Ca content concentration of 0.1% by mass and a Sn content concentration of 2.2% by mass. And the life cycle number of the battery using the expanded grid and the expanded grid, respectively.

  From the results shown in Table 1, the battery using the positive electrode lattice alloys A1 to A5 having an Al content concentration of 0% by mass increases the number of life cycles as the Se content concentration increases regardless of the cast lattice body and the expanded lattice body. Decreased. When each of these batteries was disassembled and investigated after the end of the lifetime, all of them reached the lifetime due to corrosion of the positive grid.

  In the positive electrode lattice alloy shown in Table 1, even when the Al content concentration is 0.0005% by mass, the number of life cycles tends to decrease slightly as the Se content concentration increases. The degree of decrease is less than that of 0% by mass.

  In the positive electrode lattice alloy shown in Table 1, when the Al content concentration is 0.001 mass%, 0.01 mass% and 0.03 mass% (positive electrode lattice alloys A11 to A25), the Se content concentration is 0.01. By setting the mass% and 0.05 mass%, the extension of the life cycle number was recognized remarkably. This tendency is observed in both the cast lattice and the expanded lattice, but the effect of extending the life is particularly remarkable in the battery using the expanded lattice.

  On the other hand, even when the Al content concentration is 0.001% by mass to 0.03% by mass, when the Se content concentration is 0% by mass, 0.0005% by mass, and 0.1% by mass, the life extension effect is achieved. Was hardly obtained.

  Furthermore, in the positive electrode lattice alloy shown in Table 1, when the Al content concentration was set to 0.05 mass% (A26 to A30), the life decreased rapidly.

Therefore, excellent life characteristics can be obtained in the range of Al content concentration of 0.001 mass% to 0.03 mass% and Se content concentration of 0.001 mass% to 0.05 mass%. Regarding the mechanism of the effect, it is considered that the addition of Se refines the crystal and improves the corrosion resistance of the positive electrode lattice, but the effect is greatly influenced by the Al-containing concentration. It is presumed that Al having an l-containing concentration of 0.001% by mass to 0.03% by mass makes the dispersion of Se uniform in the alloy and improves the corrosion resistance.

  On the other hand, when the Al content concentration is 0 and 0.0005 mass%, the dispersion of Se is not uniform, and a non-uniform portion of corrosion resistance is generated in the lattice, and the portion having poor corrosion resistance is locally preferentially corroded. Therefore, it is considered that the corrosion resistance as a lattice is lowered by addition of Se.

  When the cast lattice body and the expanded lattice body are compared, it can be seen that the expanded lattice body can achieve the effects of the present invention more significantly than the cast lattice body. In the case of an expanded lattice obtained by stretching a rolled product, if there is a locally non-uniform portion in the mechanical properties of the rolled product, cracks occur in the portion where the strength is locally reduced during the expansion process. This is because this part is preferentially corroded, resulting in a problem that the life characteristics are extremely lowered.

  In the present invention, Se is uniformly dispersed and the mechanical strength is also homogenized. Therefore, it is considered that the occurrence of local cracks is suppressed and the corrosion resistance of the expanded lattice body is remarkably improved.

  Cast grids tend to be slightly less effective than expanded grids, but cast grids are easier to manufacture and produce small quantities of many types of products than expanded grids. There is an advantage that it is suitable for. Therefore, it can be said that the present invention is particularly effective for improving the life of the lead-acid battery when it is necessary to employ a cast lattice body due to limitations on manufacturing equipment costs and the like.

  Next, Table 2 was prepared using positive electrode lattice alloys B1 to B30 in which the Al content concentration and the Se content concentration were changed in a Pb alloy having a Ca content concentration of 0.1% by mass and a Sn content concentration of 1.0% by mass. The life cycle number of the battery using each of the cast lattice body and the expanded lattice body is shown.

  Although the number of life cycles tends to decrease by reducing the Sn-containing concentration from 2.2% by mass to 1.0% by mass, the same tendency as in the case of the Sn-containing concentration 2.2% by mass is obtained. ing. That is, the effect of remarkably improving the life characteristics is obtained in the range of Al content concentration of 0.001 mass% to 0.03 mass% and Se content concentration of 0.001 mass% to 0.05 mass%. It can be presumed that this effect was also obtained by the same mechanism as in the case of the Sn content concentration of 2.2% by mass.

  As the Sn content concentration in the positive electrode lattice alloy increases, the life is improved. This is due to the improvement of the mechanical strength and the corrosion resistance of the lattice by adding Sn, as is conventionally known. Although the life is extended by increasing the Sn-containing concentration, Sn is more expensive than Pb, and an increase of about 1% by mass increases the production cost of the lead storage battery.

  Therefore, in order to obtain a lead-acid battery having a longer life span, it is preferable to increase the Sn-containing concentration, but the Sn-containing concentration may be limited in terms of manufacturing cost. Even in the lead storage battery in which the Sn content concentration is limited for the purpose of reducing the manufacturing cost, by using the configuration of the present invention, the effect of extending the life can be remarkably obtained, and both the cost and the life can be achieved. The present invention is extremely effective.

Further, Tables 3 and 4 show that in the Pb alloy in which the Sn content concentration is 2.2% by mass or 1.0% by mass and the Ca content concentration is 0.04% by mass, the Al content concentration and Se
The life cycle number of the battery using each of the cast lattice body and the expanded lattice body prepared by using the positive electrode lattice alloys C1 to C30 and D1 to D30 with different content concentrations is shown.

  By comparing the results shown in Tables 3 and 4 with the results shown in Tables 1 and 2 above, when the Ca concentration was decreased from 0.1% by mass to 0.04% by mass, However, the change in the life characteristics is exactly the same as the case of the Ca content of 0.1% by mass with respect to the change in the Se content and the Al content. When the Ca-containing concentration was reduced to 0.04% by mass, a slight decrease in the strength of the lattice was observed. Therefore, deformation of the lattice due to the volume expansion of the lattice during oxidative corrosion and the resulting active material It is presumed that the dropping of the metal from the lattice increased, and the life characteristics slightly decreased.

  As described above, in a lead storage battery using a Pb—Ca—Sn alloy for the positive electrode lattice, 0.001 mass% to 0.03% by mass of Al and 0.001 mass of Se in the positive electrode lattice alloy. By containing it at a concentration of from 0.05% to 0.05% by mass, corrosion of the positive electrode grid body can be suppressed, and a lead storage battery having excellent life characteristics can be obtained.

  Moreover, about the content density | concentration of Ca and Sn, the effect of this invention in the range of Sn: 1.0-2.2 mass% and Ca: 0.04-0.10 mass% which are normally used as a positive electrode grid body. I was able to confirm that

  Since the lead storage battery according to the present invention can prevent a decrease in life due to corrosion of the positive electrode grid, which is a problem when used at high temperatures, and can obtain a long-life lead storage battery, lead used in high temperatures such as a lead storage battery for vehicles Suitable for storage batteries.

Claims (2)

A lead-acid battery including a positive electrode lattice body made of a Pb-Ca-Sn alloy, wherein the Pb-Ca-Sn alloy contains 0.001% by mass to 0.03% by mass of Al, and 0.001% by mass to A lead acid battery comprising 0.05% by mass of Se. The lead-acid battery according to claim 1, wherein the positive electrode grid is an expanded grid obtained by expanding the rolled body of the Pb-Ca-Sn alloy.