JP6066119B2 - Liquid lead-acid battery - Google Patents

Description

  The present invention relates to a liquid lead-acid battery, and particularly to prevention of softening of a positive electrode active material.

  The use of liquid lead-acid batteries in an incompletely charged state improves the energy efficiency of automobiles. For example, in an idling stop vehicle, the fuel consumption is reduced by stopping the engine each time the vehicle is stopped, and the engine is started with the electric power from the storage battery when starting. For this reason, the storage battery is used in a state of insufficient charge. Not only idling stop vehicles, but avoiding overcharging of the storage battery in order to improve energy efficiency, and since the electric power taken out from the storage battery is increasing, the storage battery is often placed in an insufficiently charged state.

  When the lead storage battery is used in an insufficiently charged state, lead sulfate, which is difficult to reduce, accumulates in the negative electrode active material, resulting in a decrease in durability. It is known that the accumulation of lead sulfate can be suppressed by containing a large amount of carbon black in the negative electrode active material.

  One of the life factors of a liquid lead acid battery is softening of the positive electrode active material. Softening of the positive electrode active material is likely to occur by repeating deep discharge and charging. In this regard, Patent Document 1 (Japanese Patent Application Laid-Open No. 2010-67522) discloses that a positive electrode active material is manufactured using lead powder, a low lead tanning rate, and an antimony compound. It is disclosed that the softening of the positive electrode active material can be suppressed by incorporating the antimony compound in the positive electrode active material into the active material crystal.

  Patent Document 2 (Japanese Patent Laid-Open No. 2003-338285) discloses that sulfation of a negative electrode active material can be suppressed by including a bisphenol-based condensate and carbon black in the negative electrode active material of a lead storage battery. By the way, when a large amount of carbon black is contained in the negative electrode active material, the carbon black flows out into the electrolytic solution, and the liquid level of the electrolytic solution becomes invisible. Even when a liquid level sensor is provided to monitor the liquid level, the liquid level sensor is contaminated by carbon black, and it becomes difficult to detect the liquid level. Then, it becomes difficult to replenish the lead storage battery. However, Patent Document 2 does not consider the detection of the liquid level because it is preferably applied to a control valve type lead-acid battery. According to the inventor's experiment, when, for example, 1.5 mass% of carbon black was contained in the negative electrode active material, the carbon black concentration in the electrolytic solution was about 60 massppm, and the liquid level could not be visually recognized.

  Patent Document 3 (Japanese Patent Application Laid-Open No. 2010-123402) discloses that a slurry containing activated carbon, carbon black, carboxymethyl cellulose (hereinafter referred to as CMC) and latex is applied to the surface of the negative electrode active material. However, Patent Document 3 does not consider mixing lead powder, carbon black, and CMC. Further, according to the experiment by the inventors, the outflow amount of carbon black can be reduced to a fraction of that in the case where the negative electrode active material in which carbon black and CMC are mixed with lead powder does not contain CMC. However, the turbidity of the electrolyte could not be reduced sufficiently.

JP2010-67522 JP2003-338285 JP2010-123402

  An object of the present invention is to provide a liquid lead-acid battery that can suppress softening of the positive electrode active material and sulfation of the negative electrode active material, and further reduces the turbidity of the electrolyte.

The present invention relates to a liquid lead-acid battery comprising a negative electrode active material mainly composed of spongy lead, a positive electrode active material mainly composed of lead dioxide, and a flowable electrolyte containing sulfuric acid. Active material is 0.5 mass% or more and 2.5 mass% or less carbon black, and 0.01 mass% or more and 0.25 mass% or less of carboxymethylcellulose, or acid form, and 0.01 mass% or more and 0.3 mass% per 100 mass% of spongy lead % Of polyacrylic acid or a salt thereof, polymethacrylic acid or a salt thereof, polymaleic acid or a salt thereof, and a copolymer thereof with another olefin, and 0.1 mass% or more and 0.9 mass % Of a water-soluble polymer composed of a linear bisphenol-based condensate having a sulfonic acid group, and the positive electrode active material contains 0.02 mass% or more and 0.30 mass% or less of antimony in terms of metal. Features.

In this specification, the content of carbon black or the like in the negative electrode active material indicates the amount of spongy lead in the negative electrode active material as 100 mass%. When the negative electrode active material contains lead sulfate, lead sulfate is reduced to spongy lead to determine the amount of spongy lead. The antimony content in the positive electrode active material is converted to metal antimony and determined based on the mass of the formed positive electrode active material. If the positive electrode active material contains lead sulfate, it is converted to lead dioxide. The positive electrode active material is taken out from the positive electrode plate, washed with water and dried to remove water and sulfuric acid, and the mass of the positive electrode active material is measured. Preferably, the positive electrode active material contains 0.04 mass% or more and 0.25 mass% or less of antimony converted to metal in the already formed state. In the present invention, the negative electrode active material is at least one of carboxymethyl cellulose, polyacrylic acid or a salt thereof, polymethacrylic acid or a salt thereof, polymaleic acid or a salt thereof, and a copolymer of these with another olefin. Contain one substance and do not need to contain both. When carboxymethyl cellulose is contained, the content is 0.01 mass% or more and 0.25 mass% or less per 100 mass% of spongy lead. Polyacrylic acid or a salt thereof, polymethacrylic acid or a salt thereof, polymaleic acid or a salt thereof, and a copolymer of these with another olefin may be collectively referred to as a polycarboxylic acid. When polycarboxylic acid is contained, the content is 0.01 mass% or more and 0.3 mass% or less in terms of acid type per 100 mass% of spongy lead.
The content of the additive in the negative electrode active material is the content at the stage of chemical conversion . Chemical conversion means a process in which basic lead sulfate and lead oxide are oxidized in a sulfuric acid aqueous solution to be converted into a positive electrode active material lead dioxide, and similarly reduced in a sulfuric acid aqueous solution to be converted into a negative electrode active material metal lead. .

The negative electrode active material is a water-soluble polymer (hereinafter simply referred to as bisphenol-based condensate) composed of at least one member of the group consisting of cellulose ether, polycarboxylic acid and salts thereof and a bisphenol-based condensate having a sulfonic acid group. contains. Bisphenol condensate
(-(OH) (RSO3H) Ph-X-Ph (OH) (R'SO3H) CH2-) n
(1)
(-(OH) (RSO3H) Ph-X-Ph (OH) CH2-) n
(2)
X is a SO2 group, an alkyl group or the like, and two phenyl groups may be directly bonded without containing X. In (1) and (2), two phenyl groups per monomer are incorporated into the main chain of the bisphenol-based condensate, but one of the two phenyl groups is incorporated into the main chain and the other is incorporated into the side chain. May be. Furthermore, bisphenol and sodium phenolsulfonate may be contained in the monomer. In the above example, dehydration condensation with formaldehyde CH2O is used, and the monomer is polymerized via the methylene group -CH2-, but the other party of the condensation reaction is arbitrary.

  Bisphenol S when X is SO2 group, bisphenol A when X is -C (CH3) 2-, bisphenol F when X is -CH2-, and bisphenol S are used in the examples. , Bisphenol F may be used with the same result, or the type of formula (1) or the type of formula (2) may be used. The molecular weight of the bisphenol-based condensate is arbitrary, for example, about 4,000 to 250,000, and the influence of the molecular weight is small. Bisphenol condensates are similar to lignin sulfonic acids often added to negative electrode active materials in that they are water-soluble polymers containing aromatic rings, but bisphenol condensates are carboxy groups, ether groups and alcohols. It differs from lignin sulfonic acid in that it does not have a functional hydroxyl group and is a linear polymer rather than a network.

R and R ′ are appropriate alkyl groups such as a methylene group, but the sulfonic acid group —SO 3 H may be directly bonded to the phenyl group without using an alkyl group. Furthermore, the sulfonic acid group is a substituent for enhancing the water solubility of the polymer, and a copolymer of bisphenol S and sodium phenolmethylene sulfonate having no sulfonic acid group may be used. The hydrogen of the —SO 3 H group may be replaced with an appropriate cation such as Na + ion, particularly an alkali metal ion, in the negative electrode active material. further
The -RSO3H group, -R'SO3H group, -CH2- group are located, for example, in the ortho position relative to the -OH group of the phenyl group (Ph), and the bisphenol monomer is passed through the -CH2- group which is the partner of dehydration condensation. Are connected to each other. Many commercially available bisphenol-based condensates have two sulfonic acid groups per monomer, but the number of sulfonic acid groups per monomer is arbitrary.

Cellulose ether changes between a water-soluble form and a water-insoluble form. For example, cellulose ether is added as a water-soluble salt such as Na salt, and reacted with H + ions in the electrolyte solution. It is preferably present in the negative electrode active material as an insoluble acid type.
The polycarboxylic acid is a compound such as polyacrylic acid (-(CH2 = CHCOOH) -n), polymethacrylic acid (-(CHCH3 = CHCOOH) -n), polymaleic acid (-(CHCOOH = CHCOOH) -n), Even when it is added as a water-soluble salt such as Na salt, it is preferably reacted with H + ions in the electrolytic solution and present in the negative electrode active material in the form of an acid form insoluble in water. The polycarboxylic acid may be a copolymer with another olefin. The cellulose ether and polycarboxylic acid contents are shown in terms of acid type.

Preferably, the negative electrode active material contains at least one member of the group consisting of cellulose ethers or polycarboxylic acids, and in an already formed state, per 100 mass% of spongy lead, cellulose ether is 0.01 mass% or more and 0.25 mass%. The polycarboxylic acid is 0.01 mass% or more and 0.3 mass% or less and contains a water-soluble polymer composed of a bisphenol-based condensate in an amount of 0.1 mass% or more and 0.9 mass% or less.
As the cellulose ether, it is more preferable to use CMC (carboxymethylcellulose). As the polycarboxylic acid, it is more preferable to use polyacrylic acid.

Softening can be prevented by including antimony in the positive electrode active material.
In addition, in order to prevent softening and to suppress the increase in the frequency of water replenishment, the content of antimony in the positive electrode active material is converted to metal by converting antimony into the allowable range, considering the rate of decrease in electrolyte solution within the allowable range. Thus, it is preferably 0.04 mass% or more and 0.25 mass% or less with respect to the positive electrode active material in a chemically-formed state. By the way, the inventor confirmed that the softening of the positive electrode active material is remarkable at the upper part of the positive electrode plate, and that the softening gradually proceeds between the middle part and the lower part. Further, sulfation often progressed in the middle and lower parts of the negative electrode plate. This suggests that since sulfation proceeds in the middle and lower part of the negative electrode plate, the charge / discharge of the storage battery concentrates on the upper part of the positive and negative electrode plates, which promotes softening of the active material in the upper part of the positive electrode plate. Yes. Therefore, in the present invention, sulfation is prevented by containing 0.5 mass% to 2.5 mass% of carbon black per 100 mass% of spongy lead based on the negative electrode active material in a state of being formed. In the present invention, suppression of sulfation has the dual meaning of improving the durability of the negative electrode and preventing softening of the positive electrode active material. Note that carbon black of less than 0.5 mass% is insufficient to suppress sulfation, and carbon black of more than 2.5 mass% causes significant turbidity of the electrolyte as described later.
Further, the addition of antimony to the positive electrode active material makes the gas generation from the negative electrode uniform over the entire surface. As a result, carbon outflow promoted by gas generation at the time of charge and discharge is suppressed, and liquid turbidity is also suppressed.
When the carbon black concentration in the electrolytic solution is 3 mass ppm or less, the liquid level can be easily visually recognized or detected.

  In order to prevent turbidity of the electrolytic solution, it is effective to contain cellulose ether or polycarboxylic acid in the negative electrode active material. When the bisphenol condensate is added in addition to cellulose ether or polycarboxylic acid, the turbidity of the electrolytic solution can be particularly reduced. Even if the bisphenol-based condensate is contained alone, the outflow of carbon black cannot be suppressed. Furthermore, the bisphenol-based condensate has an effect of improving the low-temperature high-rate discharge performance. The cellulose ether is preferably added as an alkali metal salt. The polycarboxylic acid is most preferably polyacrylic acid, and is similarly added as an alkali metal salt, for example. By containing 0.1 mass% or more of the bisphenol-based condensate, the outflow of carbon black can be effectively suppressed, and when it exceeds 0.9 mass%, the turbidity of the electrolyte increases and the low-temperature high-rate discharge performance also decreases. When the cellulose ether and polycarboxylic acid are less than 0.01 mass%, the effect of preventing the turbidity of the electrolyte solution is low. When the cellulose ether exceeds 0.25 mass% and the polycarboxylic acid exceeds 0.3 mass%, the regenerative charge acceptance performance decreases.

If it does as mentioned above, while suppressing softening of a positive electrode active material, suppressing sulfation of a negative electrode active material, and also reducing turbidity of electrolyte solution, the liquid lead acid battery suitable for an idling stop vehicle etc. is obtained.

Manufacturing process diagram of negative electrode active material paste in Example Production process diagram of positive electrode active material paste in Example

  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.

Production of Negative Electrode Active Material Paste FIG. 1 shows the production process of the negative electrode active material paste. The amount of additive to the negative electrode active material is shown as the content per 100 mass% of spongy lead in the formed negative electrode active material. . CMC sodium salt or polyacrylic acid was dissolved or dispersed in water and then kneaded with carbon black comprising acetylene black. CMC was dissolved in water in the form of a sodium salt, but may be a potassium salt, a lithium salt, or the like. Instead of polyacrylic acid, polymethacrylic acid, polymaleic acid, or the like may be used. The number of carboxy groups per molecular weight may be reduced by using a copolymer of The polycarboxylic acid is dispersed in water as an acid, but may be dissolved in water in the form of sodium salt, potassium salt, lithium salt or the like. Instead of acetylene black, other carbon blacks such as oil furnace black and ketjen black may be used. Next, a condensate of bisphenol S as a dispersant (molecular weight of about 100,000), 0.6 mass% Ba sulfate for example with 100 mass% spongy lead, and 0.1 mass% with reinforcing agent for 100 mass% spongy lead, for example. Synthetic fiber was added and kneaded. Even when the bisphenol A condensate was used instead of the bisphenol S condensate, almost the same results were obtained, and even when the molecular weight of the bisphenol S condensate was changed to 10,000, the results were the same. Further, Ba sulfate and synthetic fiber may not be added. The paste obtained as described above is called a carbon paste.

  Lead powder produced by the ball mill method, 0.2 mass% of lignin sulfonic acid (hereinafter simply referred to as lignin) as a shrink-preventing agent, water and sulfuric acid are added to the carbon paste and kneaded to obtain a negative electrode active material paste. . The type and manufacturing method of the lead powder is arbitrary, and the order of kneading the materials is arbitrary, but before kneading with lead powder, carbon black, bisphenol-based condensate, CMC or polyacrylic acid are kneaded in advance. It is preferable to keep it.

  As conventional examples and comparative examples for the above negative electrode active materials, those that do not add CMC or polyacrylic acid, those that do not add bisphenol-based condensates, and those that use lignin sulfonic acid instead of bisphenol-based condensates did. The amount of carbon black ranges from 0.3 mass% to 3 mass%, the amount of bisphenol condensate ranges from 0.05 mass% to 1.0 mass%, and the amount of CMC and polyacrylic acid ranges from 0.005 mass% to 0.4 mass% It was changed with.

Production of Positive Electrode Active Material Paste FIG. 2 shows a production process of the positive electrode active material paste, and the amount of the additive is shown as a content per 100 mass% of the formed positive electrode active material. By adding 0.02 mass% to 0.30 mass% of antimony as Sb2O3 to 100 kg of lead powder, adding water and 0.1 mass% of acrylic fiber as a reinforcing agent, kneading, adding sulfuric acid and kneading again, positive electrode active A substance paste was prepared. Antimony may be added in the form of antimony sulfate (Sb2 (SO4) 3).

Assembly of lead-acid battery
The negative electrode active material paste was filled into an expandable negative electrode grid using a Pb—Ca—Sn alloy system to obtain a negative electrode plate. The negative electrode plate has a width of 137 mm, a height of 115 mm, and a thickness of 1.3 mm, and the composition and manufacturing method of the negative electrode grid are arbitrary. The positive electrode active material paste was filled in an expandable positive electrode grid with a Pb—Ca—Sn alloy system to obtain a positive electrode plate. The positive electrode plate has a width of 137 mm, a height of 115 mm, and a thickness of 1.6 mm, and the composition and manufacturing method of the positive electrode grid are arbitrary. It should be noted that antimony may be further contained in a portion other than the positive electrode active material by attaching a Pb—Sb alloy foil to the positive electrode lattice.

  The negative electrode plate and the positive electrode plate are aged and dried at 35 ° C., the negative electrode plate is wrapped in a polyethylene separator, and two positive electrode plates and one negative electrode plate in parallel are used for evaluation of turbidity of the electrolyte and initial performance. And set in the battery case. For evaluation of durability performance, eight parallel negative electrode plates and seven parallel positive electrode plates were set in the battery case. A liquid lead-acid battery was obtained by pouring dilute sulfuric acid (specific gravity 1.285 at 25 ° C.) as an electrolytic solution into the battery case and then forming the battery case.

Measurement of electrolyte turbidity Make a standard sample in which acetylene black is dispersed in the electrolyte at a concentration of 1massppm to 300massppm, compare the degree of turbidity of the electrolyte 30 minutes after formation with the degree of turbidity of the standard sample, The acetylene black content in the electrolytic solution in the liquid lead-acid battery was determined. When the content of carbon black in the electrolyte is 3 massppm, it does not hinder the visual recognition of the liquid level, but when it exceeds 6 massppm, the visual recognition becomes difficult.

Measurement of initial performance As low-temperature high-rate discharge performance, the time (seconds) until the terminal voltage of the storage battery dropped to 1.0 V due to the discharge current of 37.5 A was measured in an environment where the room temperature was -15 ° C. In addition, as a regenerative charge acceptance performance, a storage battery with 90% charge is placed in an environment with a room temperature of 25 ° C, charged at a constant voltage of 2.4V for 10 seconds with a maximum charging current of 12.5A, and the amount of electricity received by the storage battery during this time (A · s unit) was measured. The initial performance is expressed as an average value of the results of three storage batteries.

Measurement of endurance performance Before measuring the endurance performance, the turbidity of the electrolytic solution after the formation of the battery case was measured.
Every time four cycles consisting of a discharge of 1 hour at 20 A and a charge of 4 hours at 5.15 A were performed, a judgment discharge was performed at 20 A until the terminal voltage of the storage battery dropped to 1.7 V. After the judgment discharge, 5A is charged for 5 hours, and then a cycle consisting of 20A for 1 hour discharge and 5.15A for 4 hours is executed. The ambient temperature was 40 ° C., and the life was determined when the discharge amount in the judgment discharge was less than 24 Ah. The durability performance is expressed as an average value of the results of three storage batteries.

Lead sulfate accumulation rate of the negative electrode active material In order to confirm the state of sulfation of the negative electrode active material, lead sulfate accumulated in the negative electrode at the end of its life was measured, and the lead sulfate accumulation rate divided by the number of cycles was calculated. As a result, when the negative electrode active material contains carbon black of 0.5 mass% or more with respect to 100 mass% of spongy lead, the lead sulfate accumulation rate is small, sulfation is slight, and when containing 0.3 mass% carbon black, the negative electrode It was confirmed that the lead sulfate accumulation rate was large from the middle to the lower part of the plate, and sulfation proceeded easily.
In addition, the measurement of lead sulfate was performed by washing the electrode plate taken out of the battery with water, taking out all of the active material from the lattice in a dried state after the active material became neutral, and pulverizing it as a sample.

Test Examples using CMC Tables 1 and 2 show the results of test examples in which CMC sodium salt was added to the negative electrode active material. Other metal salts may be included instead of sodium salts. The unit of the content in Table 1 is mass% or massppm in which the spongy lead in the negative electrode active material is 100 mass%, and in Table 2 is mass% in which the formed positive electrode active material is 100 mass%.

Table 1 shows the turbidity and initial performance of the electrolyte. The combination of CMC between 0.01 mass% and 0.25 mass% and the bisphenol condensate between 0.1 mass% and 0.9 mass% reduces the turbidity of the electrolyte to 3 massppm or less. You can see that This combination also shows that the low-temperature high-rate discharge performance can be over 200 s and the regenerative charge acceptance performance can be over 104 A · s. An excessive amount of bisphenol-based condensate causes turbidity of the electrolytic solution, and a bisphenol-based condensate having a mass of less than 0.1 mass% is less effective. Furthermore, the bisphenol-based condensate has an effect of improving the low-temperature high-rate discharge performance. The turbidity of the electrolyte can be reduced by adding lignin sulfate together with barium sulfate or the like instead of the bisphenol condensate, but it is not as effective as the bisphenol condensate and the initial performance is inferior to that of the bisphenol condensate.
In the cells for evaluating the durability performance, the carbon black in the liquid in all the cells was 3 mass ppm or less, and the evaluation of liquid turbidity was sufficient.

Table 2 shows the durability performance in terms of the number of life cycles, and also shows the rate of liquid reduction of the electrolyte. The life of the storage battery was caused by softening of the upper part of the positive electrode active material. When the carbon black content of the negative electrode active material was 0.3 mass%, sulfation progressed from the middle to the lower portion of the negative electrode active material, and when the carbon black content was 0.5 mass% or more, the sulfation of the negative electrode active material was slight. The number of life cycles is significantly improved by combining carbon black of 0.5 mass% or more and antimony of 0.04 mass% or more, but antimony is 0.30.
When mass% was added, the liquid reduction rate was remarkably increased. As shown in Table 1, since the turbidity of the electrolyte increases when the carbon black content is 3 mass%, the carbon black content is 0.5 mass% or more and 2.5 mass% or less.

  Sulfation is likely to proceed from the middle to the bottom of the negative electrode plate, where it is difficult to fully charge. As the sulfation of the negative electrode proceeds, the opposing portions of the positive electrode are less likely to contribute to charge / discharge, and the charge / discharge concentrates on the upper part of the positive electrode. Accordingly, softening of the positive electrode active material is accelerated by sulfation, and in addition to containing antimony in the positive electrode active material, softening of the positive electrode active material can be effectively performed by adding 0.5 mass% or more of carbon black to the negative electrode active material. Can be prevented.

Test example using polyacrylic acid Tables 3 and 4 show the results when polyacrylic acid was used. The results are the same as when CMC is used, and the effects of CMC and polyacrylic acid on the negative electrode active material are equivalent. The unit is the same as in Tables 1 and 2.

  In order to confirm the effects of cellulose ether and carboxylic acid, a liquid lead-acid battery in which the binder was changed to a similar water-soluble polymer was prototyped. Sodium salt of carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), polyvinyl alcohol (PVA), hydroxyethyl cellulose, and polyacrylic acid were dissolved or dispersed in water. Add ketjen black as an example of carbon black to this solution or dispersion, knead for 5 minutes, and then 0.6 mass% barium sulfate and acrylic for bisphenol condensate (molecular weight 100,000) and 100 mass% spongy lead. A 0.1 mass% fiber was added and kneaded for 10 minutes to obtain a carbon paste. Lead powder is added to carbon paste and kneaded for 5 minutes. After adding 0.2 mass% lignin sulfonic acid and water to 100 mass% of spongy lead, kneaded, and after adding sulfuric acid dropwise, kneaded for another 10 minutes. did.

  With respect to these negative electrode active material pastes, it was investigated whether or not a paste lump could be formed and whether or not the negative electrode grid could be filled. For those that can be pasted and filled into the anode grid, liquid lead-acid batteries are prototyped in the same manner as the samples in Table 1, and the electrolyte is collected from the batteries approximately 30 minutes after the formation. The carbon concentration was estimated. The results are shown in Table 5. Styrene butadiene rubber could not be pasted or filled, and polyvinyl alcohol could be pasted but could not be filled. Hydroxyethyl cellulose had a liquid turbidity of 60 massppm and lacked visibility of the liquid level.

Claims (3)

In a liquid lead acid battery comprising a negative electrode active material mainly composed of spongy lead, a positive electrode active material mainly composed of lead dioxide, and a free flowing electrolyte containing sulfuric acid,
The negative electrode active material is in a formed state, per 100 mass% of spongy lead,
Carbon black of 0.5mass% or more and 2.5mass% or less,
0.01 mass% or more and 0.25 mass% or less of carboxymethyl cellulose, or in terms of acid form, 0.01 mass% or more and 0.3 mass% or less of polyacrylic acid or a salt thereof, polymethacrylic acid or a salt thereof, polymaleic acid or a salt thereof, And copolymers thereof with other olefins, and at least one substance therein,
Containing 0.1 mass% or more and 0.9 mass% or less of a water-soluble polymer comprising a linear bisphenol-based condensate having a sulfonic acid group,
The positive electrode active material contains 0.02 mass% or more and 0.30 mass% or less of antimony in terms of metal. The liquid lead acid battery according to claim 1, wherein the electrolytic solution has a carbon black concentration of 3 mass ppm or less in a chemical-formed state. The lead acid battery according to claim 1, wherein the lead acid battery is used for an idling stop vehicle.

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