JP2005122922A - Manufacturing method of grid for lead acid battery and lead acid battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively suppress early capacity drop caused in a lead acid battery using Pb or non-Sb based alloy for a grid, by uniformly covering the surface of the grid with a very small amount of Sb in a short time, to provide a manufacturing method of the grid for the lead acid battery, capable of curbing influence of self discharge caused by Sb as much as possible, and to provide the lead acid battery having stable life performance and the grid manufactured by this method. <P>SOLUTION: In this manufacturing method of the grid for the lead acid battery, Sb is electrodeposited on the surface of Pb or non-Sb based alloy grid in sulfuric acid aqueous solution in which a Sb compound is dissolved. This lead acid battery having the grid is manufactured by this method. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a lead-acid battery grid and a lead-acid battery.

  At present, lead-acid batteries are widely used in various fields including automobiles and industrial use, and there is a strong demand for weight reduction, cost reduction, maintenance-free, long life, and quality stabilization.

  Lattice members used in lead-acid batteries include pure lead (hereinafter referred to as “Pb”), lead alloys containing antimony (hereinafter referred to as “Sb-based lead alloys”), and lead alloys not containing antimony (hereinafter referred to as “non- It is broadly classified as “Sb-based lead alloy”. In recent years, maintenance-free and non-leakable liquid characteristics have been regarded as important, and control valve type lead-acid batteries having such characteristics have become widespread. It is well known that Pb or a non-Sb lead alloy is suitable for the lead-acid battery to maintain the maintenance-free and leakage-free characteristics.

  However, when a lead storage battery using Pb or a non-Sb-based lead alloy is used for the positive electrode grid, especially in a condition where the discharge depth is shallow and overcharged, or in a trickle or float usage condition where charging is constantly performed, the positive electrode grid Since the oxidation of the metal oxide proceeds excessively, the portion is preferentially discharged at the time of discharge, and an insulating layer of lead sulfate is formed at the interface between the lattice of the positive electrode plate and the active material, and the capacity may be lowered early.

  On the other hand, when an Sb-based lead alloy is used for the lattice, the mechanism is not clear, but the early capacity reduction does not occur. However, if Sb is present in the lattice, self-discharge increases, deterioration due to insufficient charging of the negative electrode plate occurs, and the maintenance-free function that is achieved by the method of absorbing the oxygen gas generated at the positive electrode at the negative electrode can be maintained. I have the problem of disappearing.

  As one of the countermeasures, as proposed in Patent Documents 1 to 4, a Pb or non-Sb lead alloy lattice is used, Sb or a compound thereof is contained in the positive electrode active material, or Sb is added to the lattice surface. It is known that the above-mentioned early capacity reduction can be reduced by making it adhere.

JP 58-209865 A JP 07-147160 A Japanese Patent Laid-Open No. 10-112324 JP 2002-216774 A

  In a lead storage battery using Pb or a non-Sb-based lead alloy for the positive electrode lattice, the cause of the early capacity reduction is the interface between the active material and the lattice, so the method of adding Sb to the positive electrode active material does not have much addition amount. And sufficient effect is not obtained. However, if the addition amount is large, the same problem as the above-described Sb-based lead alloy lattice occurs.

  On the other hand, the method of spraying Sb or a compound thereof on the lattice surface or dipping the lattice in a solution in which the substance is dissolved is more effective than the method of adding the substance to the positive electrode active material. It is not easy to uniformly coat the lattice surface, and if the lattice surface is not completely coated with Sb, the effect is not sufficient. In such a state, the amount of Sb becomes too large and the same as above. Adverse effects of Sb occur. Therefore, a method for uniformly coating the lattice surface with a small amount of Sb has been desired.

  The objective of this invention is providing the manufacturing method of the grid for lead acid batteries which can suppress the self-discharge resulting from Sb as much as possible, and the lead acid battery with the stable lifetime performance using the said grating | lattice.

  The inventor of the present application has studied a method for uniformly coating the lattice surface with a small amount of Sb, and an effective method is to deposit Sb on the surface of Pb or a non-Sb lead alloy lattice in an aqueous sulfuric acid solution in which an Sb compound is dissolved. I found out.

  The invention of claim 1 is characterized in that Sb is electrodeposited on the surface of Pb or a non-Sb lead alloy lattice in a sulfuric acid aqueous solution in which an Sb compound is dissolved.

  The invention of claim 2 is a lead storage battery comprising the storage battery grid manufactured by the manufacturing method of claim 1.

  As described above, by adopting a method in which Sb is electrodeposited on the surface of Pb or non-Sb lead alloy lattice in a sulfuric acid aqueous solution in which an Sb compound is dissolved, the lattice surface is made uniform with a small amount of Sb. Moreover, since it is coated in a short time, Sb works effectively, and it is possible to greatly reduce the early capacity drop that occurs in lead-acid batteries using Pb or non-Sb lead alloy grids, and the absolute amount of Sb Therefore, even if Pb or non-Sb lead alloy lattice is used, a lead storage battery with stable life performance can be obtained, and its industrial effect is extremely large. is there.

The best mode for carrying out the present invention is to immerse a Pb or non-Sb lead alloy lattice in dilute sulfuric acid having a specific gravity of 1.100 to 1.400 in which Sb ₂ O ₃ is dissolved, and use the lattice as a cathode. And performing electrolysis. Then, Sb dissolved in dilute sulfuric acid is electrodeposited on the lattice. By this method, the lattice surface can be uniformly covered in a very short time with a small amount of Sb.

The amount of Sb ₂ O ₃ dissolved in dilute sulfuric acid having the above specific gravity is 0.01 to 0.1% by mass. If electrolysis is performed using the Pb or non-Sb lead alloy lattice as a cathode in the solution, the lattice mass 0.001 to 0.01% by mass of Sb is electrodeposited on the lattice surface. It was found that the electrodepositing method can uniformly coat the lattice surface with Sb even with such a small amount.

The present invention will be described in detail based on examples.
(Example 1)
A grid for a control valve type lead storage battery of C ₅ = 7 Ah (C: rated capacity, ₅ : 5 hour rate) made of a Pb-0.08 mass% Ca-1.2 mass% Sn alloy was prepared. Next, a solution in which Sb ₂ O ₃ is dissolved in dilute sulfuric acid having a specific gravity of 1.050 to 1.400 is prepared, and electricity is used under the condition of 0.04 A / grid weight (g) × 30 seconds using the lattice as a cathode. Decomposition was performed to deposit Sb on the lattice surface. The contents are shown in Table 1.

As shown in Table 1, in the diluted sulfuric acid having a specific gravity of 1.050, the dissolved amount of Sb ₂ O ₃ was 0.005% by mass (the dissolved amount is expressed by mass% with respect to the mass of the diluted sulfuric acid solution). The dissolution amount of Sb ₂ O ₃ at a specific gravity of 1.10 to 1.300 increases as the specific gravity increases, but is fixed at 0.01% by mass in the test of the present invention (C, D, E). At a specific gravity of 1.400, a solution having a dissolution amount of 0.01% by mass and a solution having a saturated dissolution amount of 0.1% by mass was prepared (symbols F and G). The amount of Sb electrodeposited on the lattice after electrolysis is as shown in Table 1. The amount of Sb electrodeposited is expressed in mass% with respect to the lattice mass.

  As a result of cutting the section of the lattice on which Sb was deposited and analyzing with a scanning electron microscope (SEM), it was found that a thin Sb layer of 1 to 10 μm was uniformly formed on the lattice surface.

It is well known that the solubility of Sb ₂ O ₃ in dilute sulfuric acid increases as the specific gravity increases. However, the higher the specific gravity of dilute sulfuric acid, the higher the corrosivity, so the equipment for performing electrodeposition according to the present invention. However, the test was not performed for 1.400 or more.

  The conventional grid (symbol A) that has not been subjected to electrodeposition treatment and the grid (symbols B to G) that have been subjected to electrodeposition treatment of Sb are each filled with a positive electrode paste of a regular method, and after aging and drying, an unformed positive electrode A plate was made.

In addition, as a comparative product, Sb ₂ O ₃ was converted into the amount of Sb with respect to the raw material as a positive electrode paste raw material of a regular method in a Pb-0.08 mass% Ca-1.2 mass% Sn alloy lattice as in the example. Then, 0.1% by mass added was filled, and after aging and drying, an unformed positive electrode plate (symbol H) was produced.

  On the other hand, the negative electrode plate is filled with a negative electrode paste in which a predetermined amount of an organic expander, carbon, and barium carbonate is added to the same Pb-0.08 mass% Ca-1.2 mass% Sn alloy lattice as the above positive electrode plate, and is aged and dried. Then, an unformed negative electrode plate was produced.

And the unformed positive electrode plate and unformed negative electrode plate are laminated via a separator consisting of ultrafine glass fiber fiber diameter 10 [mu] m, to form an electrode plate group, the rated capacity of the valve-regulated lead-acid battery of 7Ah in C ₅ Produced.

  After injecting a predetermined amount of dilute sulfuric acid having a specific gravity into these storage batteries, initial charging was performed in the battery case by a regular method, and after completion, a control valve was attached to the liquid inlet to complete the storage battery.

  The control valve type lead acid battery was subjected to a life test under the following conditions.

Discharge: 1.4 A x 1.5 hours Charging: 2-stage constant current charge (1.4 A x 1.35 hours + 0.35 A x 2.7 hours)
Left: 6 hours Temperature: 40 ° C
A life test was conducted in which the above discharge / charge / stand was one cycle.

  As described above, the early capacity reduction of a lead storage battery using Pb or non-Sb lead alloy lattice is less likely to occur under the condition that the amount of discharge is small and then overcharge with a large amount of charge is repeated. The charging conditions were set from such a viewpoint. In other words, the discharge amount is 1.4A × 1.5 hours = 2.1 Ah, which is as small as 30% of the rated capacity 7 Ah, and the charge amount is usually charged at a charge amount of 110 to 115% of the discharge amount. On the other hand, it increased to 135%. However, the two-stage constant current charging method was adopted because the charging current is large when charging is continued with the initial 1.4A, the charging efficiency is poor, the gas generation at the end of charging is increased, the electrolyte is depleted, In order to prevent the storage battery performance from deteriorating for other reasons, the current reached 90% of the discharge amount, and the current was reduced to 0.35 A.

  As the temperature is high, early capacity drop tends to occur. In addition, a 6-hour leave was inserted for each release / charge. The cause is not clear, but it is known that if a stand is inserted after charging, an early capacity drop tends to occur.

  The results of the life test are shown in FIG.

  FIG. 1 shows the change of the capacity of each storage battery with respect to the discharge / charge cycle, and the capacity is expressed as a ratio (%) when the initial capacity of each storage battery is 100.

  As shown in FIG. 1, since this test is a condition in which early capacity reduction is likely to occur, the conventional storage battery A in which Sb is not electrodeposited on the lattice has a capacity of 40% of the initial value at the time of 50 cycles. It became the following. On the other hand, the storage battery B having an Sb electrodeposition amount of 0.0007% by mass showed the effect, but the capacity decreased to the initial 50% in 700 cycles because the amount of Sb electrodeposition was small. On the other hand, the storage batteries C to F having an electrodeposition amount of 0.001% by mass maintained the capacity of 75% or more of the initial value when the effect became remarkable and 800 cycles passed. Furthermore, the storage battery G having the largest amount of Sb electrodeposition of 0.01% by mass maintained a capacity of 80% or more at the time of 800 cycles, and exhibited a better life performance.

  On the other hand, the storage battery H in which 0.1% by mass of Sb was added to the positive electrode active material as a comparative product, although the effect was recognized, the effect was not sufficient even though the addition amount was large, and the capacity was reached at 500 cycles. Has dropped to 50%. The cause is considered to be because it did not act effectively on the lattice interface because Sb was added to the active material.

  As described above, the method of the present invention in which Sb is electrodeposited on the lattice surface can be obtained with a very small amount of Sb as compared with the conventional method, and the harmful effects of Sb are hardly affected. Became clear.

  As shown in the examples, the amount of Sb electrodeposited on the lattice surface was preferably 0.001 to 0.01% by mass, and the amount of electrodeposition was expressed with respect to the lattice mass. Although it is a very small amount, as a result of confirmation by SEM as described above, Sb is concentrated in a very thin layer of 1 to 10 μm on the surface of the lattice and covers the surface of the lattice. This test revealed that Sb works effectively even in a trace amount.

  When the electrodeposition amount of Sb in the present invention is expressed as a ratio to the lattice weight, it is a very low value. For example, Sb + Sn included in the special species of lead ingot (pure lead) defined in JIS H 2105 is With respect to a standard of 0.005% by mass (Sb: 0.0025% by mass if Sb and Sn are the same amount) or less, the Sb content at which the effect of the present invention is obtained is 0.001% by mass lower than that. Even if it exists, since the Sb is concentrated in the very thin part of the grating | lattice surface as confirmed by SEM, it cannot be overemphasized that the effect was acquired.

  In addition, the amount of Sb electrodeposited on the lattice surface in this test is limited to the amount of Sb dissolved in sulfuric acid, and even if the electrodeposition time is increased by 30 seconds or more in this test, the first electrodeposition is 1 to 10 μm. The number of layers did not increase. Also in this sense, it has been found that the method of the present invention has an advantage that no adverse effect due to a large amount of Sb occurs.

  In this example, a Pb-0.08 mass% Ca-1.2 mass% Sn alloy lattice was tested, but Pb, Pb-Ca alloy, Pb-Ca-Sn-Ag alloy and Pb-Sn alloy lattice were also tested. Tests have been conducted with similar results.

  Further, in this embodiment, the test results of the control valve type lead storage battery in which the electrolyte is impregnated / held in the positive / negative electrode plates and the separator and no free electrolyte exists, but Pb or a non-Sb lead alloy is used. In other tests, it has been confirmed that the same effect can be obtained by using the grid of the present invention for a so-called liquid lead-acid battery in which the electrolyte is sufficiently present.

The figure which shows the change of the capacity | capacitance of each storage battery with respect to a discharge / charge cycle.

Claims (2)

A method for producing a lead-acid battery grid, comprising depositing Sb on the surface of a Pb or non-Sb lead alloy grid in an aqueous sulfuric acid solution in which an Sb compound is dissolved. A lead storage battery comprising a grid for a storage battery manufactured by the manufacturing method according to claim 1.

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