JP5135692B2 - Lead acid battery - Google Patents

Description

  The present invention relates to a lead-acid battery.

  In general, lead-acid batteries for automobiles use a Pb—Ca alloy for the positive and negative grids for the purpose of maintenance-free, such as low self-discharge and excellent liquid reduction characteristics.

  In recent years, the use of electronics for automobile parts has been rapidly developed in order to improve vehicle fuel efficiency in consideration of the environment. As a result, the load of the lead storage battery tends to increase. In addition, with the spread of automobiles, chronic traffic congestion has occurred particularly in cities and the surrounding roads, and the temperature inside the vehicle is very high. Therefore, the lead acid battery for vehicles is required to have durability against a high electric load in a high temperature atmosphere.

  The lead-acid battery using the Pb—Ca alloy described above for the positive and negative grids has a significantly improved maintenance-free property as compared to the Pb—Sb alloy used for the grid, but as described above. Inferior in durability when used with a high electric load in a high temperature atmosphere.

  For example, Patent Document 1 shows that a lead-antimony-tin alloy layer is formed on a lead-calcium alloy lattice and the life characteristics of the lead-acid battery are improved when deep charge / discharge is repeated. Further, Patent Document 2 and Patent Document 3 describe that 0.2% by mass of at least one or at least two of bismuth, arsenic, copper, silver, and iron in a lead alloy containing antimony and tin formed on the surface of the lattice. Addition within the following ranges is indicated.

According to the configurations of Patent Document 2 and Patent Document 3, by adding bismuth, arsenic, copper, silver, or iron to the lattice surface layer, the charge potential of the negative electrode is kept constant, so that it was excellent until the end of its lifetime. It is shown that the charging efficiency can be maintained, and as a result, the high temperature durability of the lead acid battery is improved. In addition, when the total amount of metal elements such as bismuth and silver added to the lattice surface layer is not limited to 0.2% by mass or less, the rate of liquid electrolyte decrease increases, and the maintenance-free property of the lead-acid battery may be impaired. It is shown.
JP-A 63-148556 JP-A-2-299154 JP-A-3-22360

  The inventor of the present invention diligently researched the lead-antimony alloy layer formed on the lattice surface. As for bismuth, arsenic, copper and iron, in order to maintain the maintenance-free property of the lead-acid battery, the total amount However, as described in Patent Document 2 and Patent Document 3, it is necessary to limit the amount to about 0.2% by mass or less, but rather, regarding silver, maintenance-free properties in a region where the addition amount exceeds 0.2% by mass. It was found that a favorable effect can be obtained.

  Furthermore, it has been found that by adding such an amount of silver, the effect of improving the lifetime by the antimony disposed in the lattice surface layer can be obtained more remarkably.

  The present invention has been made based on such new knowledge, and provides a lead storage battery that is further improved in high-temperature life characteristics and superior in maintenance-free properties as compared with conventional lead storage batteries.

  In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention includes a lead-calcium-tin alloy lattice surface containing antimony and containing 0.25% by mass or more of silver, with the remainder being lead A lead storage battery using a grid body in which a lead-antimony-silver alloy is disposed as a positive electrode plate is shown.

  Furthermore, the invention according to claim 2 of the present invention is the lead storage battery according to claim 1, wherein the lead-antimony-silver alloy layer is formed on at least one surface of the base material sheet made of the lead-calcium-tin alloy. A lead alloy sheet is used for the lattice body.

  Furthermore, the invention according to claim 3 of the present invention is the lead storage battery of claim 2, wherein the lead-antimony-silver alloy strip is superposed on the lead-calcium-tin alloy base material strip, and simultaneously. Both are pressure-bonded by rolling, and the thickness (A) of the lead-antimony-silver alloy layer is formed to be 1.3% to 5.0% of the bone thickness (B) of the lattice body.

  The lead storage battery of the present invention has the above-described configuration, and in the lead storage battery in which the lead-antimony alloy layer is formed on the surface of the lead-calcium-tin alloy lattice, the amount of silver added in the lead-antimony alloy layer is limited. As a result, it is possible to improve the charge / discharge life of the lead-acid battery in a high temperature atmosphere while further improving the performance of the maintenance-free battery with less self-discharge and excellent liquid reduction characteristics.

  The lead acid battery of the present invention uses a lead-calcium-tin alloy lattice body surface containing antimony and 0.25% by mass or more of silver as the positive electrode lattice, with a lead-antimony-silver alloy serving as the balance lead. .

  The lead-calcium-tin alloy used as the lattice base material has mechanical strength and corrosion resistance required for the positive electrode lattice of the lead storage battery. As is conventionally known, calcium is added mainly to ensure mechanical strength, and the appropriate addition amount is 0.03% by mass to 0.15% by mass. Moreover, tin is added in order to ensure corrosion resistance with mechanical strength, The suitable addition amount is 0.5 mass%-2.0 mass%.

  The lead-calcium-tin alloy may contain elements such as bismuth, antimony, sulfur, selenium, nickel, and copper as impurities, all of which maintain the corrosion resistance and strength required for the positive electrode lattice alloy. It does not matter if it is contained within the range. In addition, some of these elements, such as antimony and copper, migrate to the negative electrode and degrade the self-discharge characteristics and liquid reduction characteristics. Therefore, the content of these elements is within the range where these characteristics do not deteriorate. Needless to say, it should be limited.

  In addition, other elements that increase mechanical strength or increase corrosion resistance can also be added to the lead-calcium-tin alloy. For example, barium addition of about 0.01% to 0.07% by mass is useful for increasing the mechanical strength of the lattice, and silver addition of about 0.005% to 0.5% by mass is corrosion resistance of the lattice. Therefore, it can be added as necessary.

  In addition, as conventionally known, when preparing a lead-calcium-tin alloy molten metal, 0.005 mass to suppress dross generation due to oxidation of calcium and a decrease in calcium content in the molten alloy. You may add about 0.1-0.1 mass% aluminum.

In the present invention, the antimony in the lead-antimony alloy layer formed on the surface of the positive electrode lattice is set to such an extent that it can be eluted into the positive electrode active material and exert its effect, for example, about 0.8% by mass to 20% by mass. be able to. In the lead-antimony alloy layer further formed on the surface of the positive electrode lattice, at least 0 . 2 Add 5% by weight or more of silver. Thereby, the lifetime characteristic in a high temperature atmosphere can be improved notably, improving the maintenance-free property of lead acid battery.

  Although it is not certain about this mechanism, it can be estimated as follows. That is, silver added to the lead-antimony alloy layer acts to increase the corrosion resistance of the lead-antimony alloy layer. As a result, it is considered that the antimony elution amount from the lead-antimony alloy layer decreases.

  If the lead-antimony alloy layer as the positive electrode lattice surface layer does not contain silver or is restricted to 0.2% by mass or less as in the conventional case, the corrosion of the lead-antimony alloy layer Thus, the transition of antimony to the positive electrode active material is presumed to be completed relatively early.

  Antimony transferred into the positive electrode active material maintains the bonding property between the positive electrode active materials and suppresses the deterioration of the active material due to the charge / discharge cycle, but part of it moves to the negative electrode. The transfer of a very small amount of antimony improves the charge acceptability of the negative electrode, but if it exceeds an appropriate amount, the maintenance-free property of the lead-acid battery is rapidly deteriorated.

  Antimony remaining in the positive electrode active material falls into a state where the antimony is taken into the inactive lead sulfate when the surrounding active material is inactivated by lead sulfate or the like, and the binding property between the active materials is reduced. It is presumed that the function of maintaining will be lost.

In the present invention, in the lead-antimony alloy layer formed on the positive electrode lattice surface, 0 . By adding 2 5 mass% or more silver, lead - oxidation rate of the antimony alloy layer is moderately suppressed, since the dissolution rate of the antimony is suppressed, antimony from the positive electrode grid surface of the cathode active material over an extended period of time It is considered to be supplied. Therefore, it is estimated that the life characteristics of the lead storage battery are improved because the modification effect of the positive electrode active material by antimony lasts for a long time.

  Conventionally, since elution of antimony is completed relatively early, it is considered that antimony in the positive electrode active material is excessive for a period of time, and this excess antimony is transferred to the negative electrode, reducing the maintenance-free property. In the present invention, it can be presumed that the rapid increase in the concentration of antimony in the positive electrode active material is suppressed, and the migration of antimony to the negative electrode, which reduces the maintenance-free property, is suppressed.

  Furthermore, due to the effect of inhibiting the corrosion of silver in the lead-antimony alloy layer formed on the lattice surface, the current used to oxidize the lead flowing in the positive electrode lattice during charging, that is, the oxidation current is suppressed, and the amount of corrosion is suppressed as a whole of the positive electrode lattice. Therefore, it is thought that it contributes to the life improvement effect of the lead storage battery.

  In order to exert the corrosion inhibition effect due to silver on the lattice base material, it is necessary to add silver to the entire lattice base material, but in the present invention, since silver can be concentrated on the surface, the amount of silver used can be reduced, This is effective in reducing the price of lead-acid batteries.

  In order to obtain the configuration of the present invention, the lead-antimony-silver alloy having the above-mentioned composition can be sprayed or dipped on the lead-calcium-tin alloy lattice. A lead-antimony-silver alloy strip is disposed on a tin alloy base strip, and a rolled lead alloy sheet having a lead-antimony-silver alloy layer formed on the surface by simultaneous rolling or the like is punched. What gave drilling processes, such as a process and an expand process, can be used as a positive electrode grid.

  As described above, when the lead-antimony-silver alloy layer is formed on the surface by simultaneous rolling, the thickness (B) of the lattice bone 2 in the positive electrode lattice 1 and the lead-antimony-silver shown in FIG. More preferably, in the thickness (A) of the alloy layer 3, the lead-antimony-silver alloy layer 3 having a thickness (A) corresponding to 1.3% to 5.0% of the thickness (B) of the lattice bone 2 is formed. . By setting the thickness (A) as described above, the adhesion between the lead-antimony-silver alloy layer 3 and the lead-calcium-tin alloy base material 4 can be improved.

  In particular, when the thickness (A) exceeds 5.0% of the thickness (B) and less than 1.3%, the lead-antimony-silver alloy layer 3 and the lead-calcium-tin alloy base material 4 Therefore, the thickness (A) is preferably 5.0% or less of the thickness (B).

Example 1
Hereinafter, the effects of the present invention will be described with reference to examples.

  In Example 1, lead acid batteries (hereinafter referred to as batteries) according to the present invention and comparative examples were prepared, and a charge / discharge life test was performed in a gas phase atmosphere at 75 ° C. In addition, it was set as the 80D26 type lead acid battery (12V55Ah) prescribed | regulated by JISD5301 (lead acid battery for start-up) with the battery of the example of this invention and the comparative example.

  The assembly and chemical charging of the batteries of the present invention example and the comparative example in this example were performed according to the following procedure.

  The positive and negative plates are kneaded by adding regular lead powder, water, sulfuric acid, and additives such as barium sulfate and lignin in the case of an expanded grid of a lead-calcium-tin alloy rolled lead alloy sheet. The combined paste-like active material was filled and aged and dried to form a positive electrode plate and a negative electrode plate (both in an unformed state), respectively.

  At this time, the positive electrode grid is composed of a lead alloy having a composition shown in Table 1 described later on one surface of a lead-calcium-tin alloy strip containing 0.05% by mass of calcium and 1.60% by mass of tin. A rolled lead alloy sheet obtained by superimposing strips and rolling and integrating them was used. In the lattice state, the thickness (A) of the lead alloy layer formed on the lattice surface was 2.0% of the thickness (B) of the positive lattice bone.

  An electrode plate group was prepared by combining each of the positive electrode plate and the negative electrode plate with a separator. In addition, the microporous polyethylene sheet made into the bag shape by the mechanical seal was used as a separator, the negative electrode plate was inserted in this bag-shaped separator, and it arrange | positioned so that a positive electrode plate and a negative electrode plate might become alternate.

  Electrode tabs having the same polarity were welded by a burning method to form a connector for connecting between the strap and the cell and / or a pole column for deriving battery output, thereby obtaining a plate group. After this electrode plate group was housed in the battery case, the cells were assembled by connecting the cells by resistance welding as in the prior art and joining the lid to the upper part of the battery case by heat welding.

A dilute sulfuric acid electrolyte solution having a density of 1.165 g / cm ³ (converted to 20 ° C.) is injected into the assembled battery, and after conducting the energization conversion, the residual electrolyte solution is discharged, and dilute sulfuric acid solution is injected again. The electrolyte density was adjusted to 1.285 g / cm ³ (20 ° C. converted value). Finally, a battery with a liquid stopper attached to the liquid mouth was used as a test battery.

  Table 1 shows the composition of the lead alloy layer formed on the surface of the positive electrode lattice in the battery of this example.

表１に示した各電池について、以下の手順により寿命試験を行った。なお、同時に寿命試験における電解液の減液量についても評価した。
（寿命試験方法）
放電：２５Ａ、２分間（７５℃）
充電：１４．８Ｖ定電圧（最大電流２５Ａ）、１０分間（７５℃）
上記の放電−充電サイクルの４８０サイクル毎に５８２Ａの定電流で判定放電を行い、判定放電の３０秒目電圧が７．２Ｖを下回った時点で寿命試験終了とした。寿命サイクル数は以下の通り求めた。

Each battery shown in Table 1 was subjected to a life test according to the following procedure. At the same time, the amount of electrolyte decreased in the life test was also evaluated.
(Life test method)
Discharge: 25A, 2 minutes (75 ° C)
Charging: 14.8V constant voltage (maximum current 25A), 10 minutes (75 ° C)
A judgment discharge was performed at a constant current of 582 A every 480 cycles of the above discharge-charge cycle, and the life test was completed when the voltage at the 30th second of the judgment discharge fell below 7.2V. The number of life cycles was determined as follows.

That is, it is assumed that the discharge 30-second voltage V _n in the n-th determination discharge is lower than 7.2V. In this case, coordinates (480 _n , V _n ) are plotted on a graph with the horizontal axis (number of cycles) -vertical axis (voltage at 30 seconds of determination discharge). Similarly, coordinates (480 (n−1), V _n−1 ) are plotted from the voltage V _{n−1 at the} discharge 30 seconds in the (n−1) th determination discharge which is the previous determination discharge, and these two The coordinates are connected by a straight line, and the horizontal axis coordinate of the point where the straight line intersects the straight line of the determination discharge 30 second voltage = 7.2 V is defined as the battery life cycle number.

  Further, the amount of liquid reduction was evaluated by the following method. That is, the battery mass is measured every charge / discharge cycle of 480 cycles (hereinafter, a series of 480 cycles of charge / discharge is assumed to be 480 cycle units), and the amount of liquid reduction is calculated from the battery mass difference before and after each 480 cycle unit. Calculated. In addition, after the liquid reduction amount calculation, distilled water corresponding to the liquid reduction was supplied to the battery.

  Table 2 shows the number of life cycles and the amount of liquid reduction of each battery described above. In Table 2, with regard to the liquid reduction amount, the liquid reduction amount in the second 480 cycle unit (liquid reduction amount 1) starting from 481 cycles and ending in 960 cycles, and the liquid reduction amount in the last 480 cycle units (life cycle test) It showed about the liquid reduction amount 2).

表２に示した結果から、正極格子表面に形成する鉛合金層にアンチモンを含み、かつ銀を０．２５質量以上添加することにより、寿命サイクル数は伸び、減液量は減少する傾向にあった。なお、鉛合金層にアンチモンを含まない、電池１３〜１６では、減液量が抑制されているが、寿命特性に劣っている。鉛合金層にアンチモンを単独で含む電池１および電池９は電池１３〜１６よりも寿命特性は大幅に改善するものの、減液量が増大する。

From the results shown in Table 2, when the lead alloy layer formed on the surface of the positive electrode lattice contains antimony and 0.25 mass or more of silver is added, the number of life cycles tends to increase and the amount of liquid reduction tends to decrease. It was. In addition, in the batteries 13 to 16 in which the lead alloy layer does not contain antimony, the amount of liquid reduction is suppressed, but the life characteristics are inferior. Although the battery 1 and the battery 9 containing antimony alone in the lead alloy layer have significantly improved life characteristics as compared with the batteries 13 to 16, the amount of liquid reduction increases.

  In the batteries 4 to 8 and the batteries 11 to 12 of the present invention, the liquid reduction amount is slightly increased as compared with the batteries 13 to 16, but the liquid reduction amount is significantly suppressed as compared with the battery 1 and the battery 9, and Excellent life characteristics.

  From the above, as described above, it is considered that silver in the lead alloy layer formed on the surface reduces the elution rate of antimony and suppresses migration of antimony to the negative electrode. Moreover, since the transition of antimony from the positive electrode lattice to the positive electrode active material proceeds little by little, it can be presumed that the effect of modifying the positive electrode active material by antimony was obtained over a long period of time, and as a result, excellent life characteristics were obtained.

  Even when antimony in the surface layer is reduced from 5.0% by mass to 0.8% by mass, if the silver is not contained in the surface layer in an amount of 0.25% by mass or more, the life performance and the liquid reducing property are obtained. It turns out that it falls. This means that even if the amount of antimony in the surface layer is simply reduced, the antimony in the surface layer elutes relatively early, and the positive electrode active material modification effect of antimony is lost early. It is considered that the antimony is present in excess in the positive electrode active material for a period of time, and antimony that is not trapped in the positive electrode active material moves to the negative electrode and deteriorates the liquid reduction property.

  Therefore, in order to improve the liquid reduction performance, it is not sufficient to reduce the amount of antimony in the surface layer, and it is considered necessary to control the antimony elution rate from the surface layer. In the present invention, it is considered that by adding 0.25% by mass or more of silver to the lead-antimony alloy, the corrosion rate of the lead-antimony alloy is reduced and the antimony elution rate can be controlled. In addition, as a result, an appropriate amount of antimony is present in the positive electrode active material over a long period of time, and it is considered that the high-temperature life of the lead storage battery is remarkably improved.

(Example 2)
Next, in Example 2, a rolled lead alloy sheet was prepared by variously changing the thickness of the lead-antimony-silver alloy layer formed on the surface of the positive electrode lattice for the battery 4, the battery 6 and the battery 8 of the present invention. The positive electrode lattice body was obtained by expanding. The lattice bone of this positive electrode lattice was observed with a stereomicroscope, and the contact state of the lead-antimony-silver alloy layer formed on the lattice surface with the lattice bone was confirmed. The thickness of the lead-antimony-silver alloy layer was varied by changing the thickness of the lead-antimony-silver alloy strip superimposed on the base material strip (thickness 10.00 mm).

  The composition and thickness of the base material strip used in Example 2 are exactly the same as those of Example 1, and are lead-calcium-tin alloys containing 0.05% by mass of calcium and 1.60% by mass of tin. is there. In addition, the contact | adherence state confirmed 10 places of the up-down direction about 10 lattice bodies each, and a total of 100 places, and measured the incidence rate of peeling of a lead-antimony-silver alloy layer.

  Moreover, 80D26 type lead acid battery similar to Example 1 was created using the positive electrode grid obtained on the same conditions, and the life test was done on the same conditions as Example 1. FIG. Table 3 shows the peel occurrence rate and the life test result of the lead-antimony-silver alloy layer.

表３に示した結果から、正極格子表面層厚（Ａ）を正極格子厚（Ｂ）の１．３０〜５．００％の範囲とすることにより、正極格子表面に形成した鉛−アンチモン−銀合金層の格子骨からの剥離が顕著に抑制され、これに応じてより優れた寿命特性を得ることができる。

From the results shown in Table 3, lead-antimony-silver formed on the surface of the positive electrode lattice by setting the positive electrode lattice surface layer thickness (A) to 1.30 to 5.00% of the positive electrode lattice thickness (B). Peeling of the alloy layer from the lattice bone is remarkably suppressed, and in accordance with this, better life characteristics can be obtained.

  When the positive electrode lattice surface layer thickness (A) is 1.00% of the positive electrode lattice thickness (B), the lead-antimony-silver alloy layer has dot-like perforations, and the base material is on the surface at this portion. It was in an exposed state. Moreover, peeling of the lead-antimony-silver alloy layer occurred in part of the periphery of the hole.

  When the positive electrode lattice surface layer thickness (A) was 7.00% of the positive electrode lattice thickness (B), the lead-antimony-silver alloy strip and the base material strip were in close contact before the expansion process. In the lattice after the expansion processing, the adhesion between the lead-antimony-silver alloy strip and the base material strip was lowered, and a peeled portion was observed.

  Therefore, when the lead-antimony-silver alloy strip and the base material strip are overlapped and joined together by simultaneous rolling, the final positive electrode lattice surface layer thickness (A) is 1.30% of the positive electrode lattice thickness (B). It is most preferable to set the thickness ratio of the lead-antimony-silver alloy strip and the base material strip so that the effect of the present invention is more remarkable.

  In this embodiment, the case where the base material strip thickness is 10.0 mm has been described. However, in the case where the base material strip thickness is 5.0 and 20.0 mm, substantially the same results are obtained. The lattice surface layer thickness (A) is most preferably 1.30% to 5.00% of the positive electrode lattice thickness (B). Similarly, when the base metal strip composition has a calcium content of 0.04 to 0.08 mass% and a tin content of 0.6 to 1.8 mass%, the positive electrode lattice surface layer By making the thickness (A) 1.30% to 5.00% of the positive electrode lattice thickness (B), peeling of the positive electrode lattice surface layer was suppressed.

  In this example, a lead-antimony-silver alloy was described as the alloy layer disposed on the surface of the positive electrode grid. However, in order to improve the overdischarge resistance of the lead-acid battery, 1. It is also possible to additionally add 0 to 10.0% by weight of tin. Even in that case, the effect of the present invention could be obtained.

  Since the present invention can remarkably improve the high-temperature life characteristics and the liquid reduction performance of the lead storage battery, it is particularly suitable for various lead storage batteries including automobile lead storage batteries.

The figure which shows the positive electrode grid used for the lead acid battery of this invention Diagram showing the cross section of the positive grid

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode grid 2 Lattice bone 3 Lead-antimony-silver alloy layer 4 Lead-calcium-tin alloy base material

Claims (3)

Lead using a lead-antimony-silver alloy containing a lead-antimony-silver alloy containing antimony on the surface of a lead-calcium-tin alloy lattice and containing 0.25% by mass or more of silver as the balance lead Storage battery. The lead acid battery according to claim 1, wherein a rolled lead alloy sheet in which the lead-antimony-silver alloy layer is formed on at least one surface on the base material sheet made of the lead-calcium-tin alloy is used for the lattice body. The lead-antimony-silver alloy layer strip is overlapped on the lead-calcium-tin alloy base strip, the two are pressure-bonded by simultaneous rolling, and the thickness (A) of the lead-antimony-silver alloy layer is determined. The lead acid battery of Claim 2 formed in thickness of 1.3%-5.0% of the thickness (B) of the bone | frame of the said lattice body.

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