JP4364054B2 - Lead acid battery - Google Patents

Description

The present invention relates to a lead-acid battery that has a long life and is excellent in capacity recoverability (charge acceptability during recovery charge) and that is particularly suitable for automobiles employing an idle stop system.

Conventionally, lead-acid batteries for automobiles are used for starter start-up, lighting, and ignition at the time of starting, called SLI batteries, and also used for the power supply of motors that are said to have more than 100 installed in high-end cars. It was. In addition to starting the starter at the time of starting, the engine drives the generator to supply electric power, so that the lead-acid battery was not discharged so deeply. Moreover, since charging from a generator often places the battery in a fully charged state, it has been required to be resistant to overcharging.
On the other hand, maintenance-free (no need for water replenishment) is required for lead-acid batteries. As a countermeasure, Pb-Ca-based materials are less likely to cause self-discharge and less decrease in electrolyte instead of conventional Pb-Sb-based alloys. Alloy substrates have been used.

However, in recent years, automobiles are strongly required to improve fuel consumption and reduce exhaust gas, and accordingly, an idling stop system has been introduced. The idling stop system is a system that stops the engine while stopping due to a signal, etc., and the power supply from the generator is also stopped by the engine stop, so that the power during this period is covered by the discharge of the lead storage battery, As a result, the lead storage battery is used in a deep charge / discharge state, and the lead storage battery using the Pb—Ca alloy substrate has a remarkably short life.

Incidentally, in a conventional lead storage battery using a Pb—Sb alloy positive electrode substrate, trivalent or pentavalent Sb ions are generated by oxidation of the substrate, and the Sb ions are strongly α-PbO at the interface between the substrate and the active material. _Two layers are formed to maintain good adhesion (conductivity) between the substrate and the active material, and the Sb ions act on the active material to gel part of it and increase the bonding force between the active material particles. As a result, the active material is difficult to soften even after repeated deep charge and discharge, and a long life is realized.

On the other hand, in the Pb—Ca-based alloy positive electrode substrate, since the effect of the Sb ions cannot be obtained, the interface between the substrate and the active material is peeled off, and the electrolytic solution (sulfuric acid) enters there to produce lead sulfate. As a result, the adhesion (conductivity) between the substrate and the active material is reduced, and therefore, in applications where deep charge / discharge is repeated, the bonding force between the active material particles is reduced early (the active material is softened), and the lifetime is Pb-Sb series. It was about half of the case where an alloy positive electrode substrate was used. Moreover, the capacity recoverability decreased when left in a discharged state for a long time.

For this reason, the same effect as in the case of using a Pb—Sb alloy positive electrode substrate by providing a layer containing Sb on the surface of the Pb—Ca alloy positive electrode substrate or adding an Sb compound to the positive electrode active material. A method (for example, Patent Document 1) or a method for expressing the effect of Sb by an element other than Sb has been proposed.

On the other hand, a method for suppressing a decrease in specific gravity of an electrolytic solution by adding alkali metal or alkaline earth metal ions to the electrolytic solution has been proposed (for example, Patent Document 3).

However, none of the above methods has improved both cycle life and capacity recovery.

JP-A 63-148556 JP 2003-109595 A JP-A-4-206150

An object of the present invention is to provide a lead storage battery using a Pb—Ca-based alloy substrate for a positive electrode, which has a long life and excellent capacity recovery.

According to the first aspect of the present invention, at least a part of the surface of the positive electrode substrate made of a lead-calcium alloy and / or the active material filled in the positive electrode substrate contains 0.005 mass% to 0.5 mass% of antimony. Furthermore, it is a lead storage battery characterized in that tin is contained in an amount of 0.005 mass% to 1.0 mass% and aluminum is contained in the electrolytic solution in an amount of 2 mass% to 50 mass% in terms of sulfate.

In the lead storage battery according to the first aspect of the present invention, since an appropriate amount of antimony is contained in at least a part of the surface of the positive electrode substrate or / and the positive electrode active material, the antimony (Sb) is oxidized to be trivalent or pentavalent. It becomes Sb ions to form a strong α-PbO ₂ layer at the interface between the substrate and the active material, and also improves the adhesion between the substrate and the active material, that is, the conductivity. Further, the Sb ions gel part of the active material. To increase the bonding force between the active material particles. In addition to its so was suitable amount of tin increases the conductivity of the active material particles by the action of the tin (tin ions), the cycle life of the lead-acid battery is further improved.

The lead acid battery of claim 1, wherein the invention are those which can be better improved life Rukoto with Pb-Ca system alloy having a predetermined composition which is excellent in corrosion resistance and mechanical properties to the positive electrode substrate.

As the Pb—Ca-based alloy having excellent corrosion resistance and mechanical properties, calcium is 0.02 mass% or more and less than 0.05 mass%, tin is 0.4 mass% or more and 2.5 mass% or less, and aluminum is 0.005 mass% or more and 0 or less. .04 mass% or less, Pb-Ca alloy containing barium in an amount of 0.002 mass% to 0.014 mass%, the balance being composed of lead and inevitable impurities, or the positive electrode substrate containing calcium in an amount of 0.02 mass% to less than 0.05 mass%, Contains 0.4 mass% to 2.5 mass% tin, 0.005 mass% to 0.04 mass% aluminum, 0.002 mass% to 0.014 mass% barium, and 0.005 mass% to 0.07 mass silver. % Or less, including at least one selected from the group of bismuth 0.01 mass% to 0.10 mass%, thallium 0.001 mass% to 0.05 mass% In addition, a Pb—Ca-based alloy whose balance is made of lead and inevitable impurities is mentioned (Japanese Patent Laid-Open No. 2003-306733).

In the present invention, the positive electrode substrate can be manufactured with high quality and efficiency by a gravity casting method, a continuous casting method, or a method of rolling an ingot.

In the present invention, antimony is contained in at least part of the positive electrode substrate surface, and / or the active material, the binding force between active material particles, and the active material and cycle life by increasing the adhesion (conductivity) between the substrate To improve. Moreover, since tin ionizes and raises the electroconductivity of an active material, cycle life is further improved. On the other hand, the aluminum contained in the electrolytic solution increases the reversibility of lead sulfate produced in both the positive and negative electrodes and improves the capacity recovery after standing for a long time.

In claim 1 the invention, at least part of the positive electrode substrate surface, or / and the amount of antimony to be contained in the active material defined below 0.005 mass% or more 0.5 mass%, more 0.005 mass% the amount of tin The reason for prescribing to 1.0 mass% or less is that any of these effects is not sufficiently obtained regardless of whether it is less than the lower limit value or exceeds the upper limit value, and if it exceeds the upper limit value, self-discharge easily occurs. Because.

In the present invention, examples of the method of incorporating antimony and tin into the positive electrode active material include a method of mixing antimony, tin oxide, sulfate, etc. with the positive electrode lead powder.

Antimony or antimony and tin in order to incorporate at least part of the positive electrode substrate surface, may, for example, a method of applying the cited positive Namariko which contains the antimony and tin in layers in at least part of the positive electrode substrate It is done.

In the present invention, aluminum contained (dissolved) in the electrolytic solution (present as ions) suppresses a decrease in the concentration of sulfate ions in the electrolytic solution when the lead storage battery is left in a discharged state for a long period of time. Capacitance recovery is greatly improved by suppressing the coarsening or densification of the lead sulfate crystals produced on the positive and negative electrodes.

In the present invention, the reason why the content of aluminum in the electrolytic solution is regulated to 2 to 50 g / liter in terms of sulfate is that the effect cannot be sufficiently obtained if it is less than 2 g / liter, and the amount exceeds 50 g / liter. This is because the electrical conductivity of the electrolytic solution is lowered and the rapid discharge characteristics at low temperature are lowered.

In the present invention, the aluminum is added to the electrolytic solution as a sulfuric acid aqueous solution such as sulfate, carbonate, bicarbonate, phosphate, borate, hydroxide, aluminate or a compound easily soluble in water. Let

The lead-acid battery of the present invention contributes to the expansion of the use of lead-acid batteries, in particular, because a long life is achieved in applications involving deep charge / discharge, such as cars employing an idling stop system, HEV, and cycle use.

Hereinafter, the present invention will be described in detail with reference to examples.

15 pieces per minute of lead alloy containing 0.04 mass% calcium, 1.0 mass% tin, 0.015 mass% aluminum, 0.008 mass% barium, the balance being lead and inevitable impurities A positive electrode substrate was manufactured by casting at a temperature of 120 ° C. for 3 hours and age-cured.

Next, antimony oxide and tin sulfate are added to the positive electrode lead powder and mixed to obtain a mixed powder. This mixed powder is prepared into a paste-like material by a conventional method, and this paste-like material is applied to the age-cured positive electrode substrate. The positive electrode substrate coated and filled, and then coated and filled with the paste-like material was aged for 24 hours in an atmosphere of a temperature of 40 ° C. and a humidity of 95%, and dried to prepare a positive electrode unformed plate. The addition amounts of the antimony oxide and tin sulfate were variously changed.

Next, a plurality of positive electrode unformed plates and a plurality of negative electrode unformed plates prepared by applying and filling a negative electrode active material on a substrate made of a Pb—Ca alloy are alternately laminated with a polyethylene separator interposed therebetween. Then, each electrode plate of this laminate is welded by the COS method to form an electrode plate group, which is accommodated in a polypropylene battery case, and an electrolytic solution to which aluminum sulfate is added is injected into the battery case to form a battery case. Then, a 12V lead acid battery (JIS size D23) with a 5-hour rate capacity of 50 Ah was manufactured (No. 1 to 8) . The amount of aluminum sulfate added was varied.

About each obtained lead acid battery, the cycle life was investigated by the JIS heavy load test. Further, the capacity recoverability after leaving in a discharged state at 60 ° C. for 4 weeks was examined.

Antimony oxide and tin sulfate are added to the lead powder for the positive electrode and mixed to obtain a mixed powder. This mixed powder is prepared into a paste-like material by a conventional method, and this paste-like material is thinly applied to the surface of the positive electrode substrate. A lead-acid battery was produced by the same method as in Example 1 (Nos. 9 to 11) except that the positive electrode lead powder (not including antimony and tin) was filled, and the same method as in Example 1 Thus, cycle life and capacity recovery were examined.

As Comparative Example 1, except that Sb and Sn are not contained in the positive electrode active material of the Pb—Ca-based alloy positive electrode substrate, the same lead storage battery (No. 12 ) as in Example 1, except that Sb is not contained in the positive electrode active material. example 1 the same lead-acid battery as (No.13), the same lead-acid battery (No.1 4) other containing no Al to Sn and the electrolyte in the positive electrode active material as in example 1, a large amount of S n in the positive electrode active material the same lead electric storage batteries other containing the example 1 (No. 15), large amounts contain Sb in the positive electrode active material, the same lead-acid battery (No.16) and other containing no Sn example 1, electrolytic The same lead storage battery (No. 17 ) as in Example 1 was produced except that the liquid contained a large amount of Al, and the cycle life and capacity recoverability were examined by the same method as in Example 1.

(1) cycle life than 130 times (long life), (2) Capacity recovery property (index) of 6 0% or higher (good), thereby satisfying the expression (3) there is no problem in other battery characteristics, three conditions The product was evaluated as overall excellent (O), and if any one of the three conditions was unsatisfactory, it was evaluated as overall inferior (x).

The investigation results of Examples 1 and 2 and Comparative Example 1 are shown in Table 1.

As is clear from Table 1, the lead storage batteries (Nos. 1 to 1 1 ) of the examples of the present invention (Examples 1 and 2 ) all have a long life, good capacity recoverability, and other battery characteristics. There was no problem and it was excellent overall. At least a portion, or / and the antimony in the active material coated filled in the positive electrode substrate (Sb) Contact Yobisuzu (Sn) is suitable amount each of the positive electrode substrate surface cause the long lifetime consisting Pb-Ca based alloy This is because the bonding force between the active material particles is increased and softening of the active material is prevented, and the adhesion (conductivity) between the substrate and the active material, and further the conductivity of the active material is maintained at a high level. The reason why the capacity recoverability is excellent is that the reversibility of lead sulfate produced in both positive and negative electrodes is improved by containing an appropriate amount of aluminum (Al) in the electrolytic solution.

On the other hand, No. 12 of Comparative Example 1 was inferior in cycle life because Sb and Sn were not contained in the positive electrode active material. No. 1 3, Sb is poor because cycle lifetime are not contained in the positive electrode active material. No. 1 4 was inferior in capacity recovery property because no Al is contained in the electrolytic solution. No. No. 15 has too much Sn. No. 16 had too much Sb, so the self discharge increased in any case. No. In No. 17, since the electrolytic solution contained a large amount of Al, the rapid discharge characteristics deteriorated. Thus, all the lead acid batteries of Comparative Example 1 were inferior overall.

In Examples 1 and 2 , an example in which an Al—Ca—Sn—Al—Ba alloy having excellent corrosion resistance and mechanical properties was used for the positive electrode substrate was described, but the alloy was further selected from the group of Ag, Bi, and Tl. In addition, the same effect can be obtained when an alloy containing an appropriate amount of at least one kind is used, and substantially the same effect can be obtained when another Al—Ca alloy is used.

In Examples 1 and 2 , the positive electrode substrate was manufactured using a book mold, but the present invention can provide the same effect when the positive electrode substrate is manufactured by other methods such as a continuous casting method and a rolling method.

Claims (1)

  Antimony is contained in an amount of 0.005 mass% or more and 0.5 mass% or less in at least part of the surface of the positive electrode substrate made of a lead-calcium alloy and / or in the active material filled in the positive electrode substrate, and further tin is 0.005 mass. A lead-acid battery characterized in that it is contained in an amount of not less than 1.0% and not more than 1.0 mass%, and aluminum is contained in the electrolytic solution in an amount of 2 to 50 mass% in terms of sulfate.