JP2013161606A - Liquid type lead acid battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid type lead acid battery in which turbidity of the electrolyte is less, and low temperature high rate discharge performance, regenerative charge acceptance performance, and durability performance under insufficient charging state are excellent.SOLUTION: The negative electrode active material of a liquid type lead acid battery contains a water-soluble polymer principally comprising a bisphenol-based condensation product having 0.5-2.5 mass% of carbon black per 100 mass% of spongy lead in transformed state, and a sulfonic acid group as a substituent group, and polycarboxylic acid compound such as poly acrylic acid. The electrolyte has a carbon black concentration of 3 mass ppm or less in transformed state.

Description

  The present invention relates to a liquid lead-acid battery, and more particularly to a liquid lead-acid battery containing a large amount of carbon black in a negative electrode active material and less turbidity of an electrolyte.

  The use of liquid lead-acid batteries in an undercharged state (PSOC) has improved 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 stops, and the engine is restarted 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. However, if carbon black is contained in an amount exceeding 0.5 mass%, for example, with respect to 100 mass% of the spongy lead of the negative electrode active material, the carbon black flows out into the electrolyte during use and adheres to the inner wall of the battery case. The visibility of the surface is reduced. In a liquid type lead-acid battery, it is necessary to compensate for the decrease in the electrolyte by adding water. Although a liquid level sensor is also provided, if the sensor is contaminated with carbon black, it becomes difficult to detect the liquid level. For this reason, it is necessary to add a large amount of carbon black to the liquid lead-acid battery while slightly turbidizing the electrolyte.

  Here is related prior art. Patent Document 1 (JP2010-123402A) discloses that a negative electrode active material of a lead storage battery is coated with a paste containing 100 parts of activated carbon, 5 parts of carbon black, 1.5 parts of carboxymethylcellulose, and 3 parts of latex. According to Patent Document 1, by covering the negative electrode active material with a paste, a decrease in battery capacity when charging / discharging between 100% and 80% charge cycles is repeated 200 cycles. Patent Document 1 further states that a salt of polyacrylic acid may be used instead of carboxymethylcellulose. However, Patent Document 1 does not examine the visibility of the liquid surface of the electrolytic solution or the addition of a bisphenol-based condensate.

JP2010-123402A

  An object of the present invention is to provide a liquid lead-acid battery that has low turbidity of an electrolyte solution and is excellent in low-temperature high-rate discharge performance, regenerative charge acceptance performance, and durability performance in a state where charging is insufficient.

The present invention relates to a liquid lead-acid battery comprising a negative electrode active material composed mainly of spongy lead, a positive electrode active material composed mainly of lead dioxide, and a flowable electrolyte containing sulfuric acid.
The negative electrode active material, per 100 mass% of the spongy lead in a chemically formed state,
With carbon black 0.5mass% or more and 2.5mass% or less,
A water-soluble polymer comprising a bisphenol-based condensate having a sulfonic acid group as a substituent;
Containing at least one polycarboxylic acid compound of the group consisting of polyacrylic acid, polymethacrylic acid, and polymaleic acid and salts thereof;
In addition, the electrolytic solution is characterized in that the carbon black concentration is 3 mass ppm or less in the already formed state. Regarding the composition of the negative electrode active material, for example, it may be simply referred to as 0.5 mass% or more and 2.5 mass% or less, etc., that the content is 0.5 mass% or more and 2.5 mass% or less per 100 mass% of spongy lead in the already formed state. . The polycarboxylic acid compound indicates the content in terms of acid type.

A water-soluble polymer composed of a bisphenol-based condensate having a sulfonic acid group as a substituent (hereinafter simply referred to as a bisphenol-based condensate)
(-(OH) (RSO ₃ H) Ph-X-Ph (OH) (R'SO ₃ H) CH _2- ) _n (1)
(-(OH) (RSO ₃ H) Ph-X-Ph (OH) CH _2- ) _n (2)
X is a SO ₂ 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. It may be. Furthermore, bisphenol and sodium phenolsulfonate may be contained in the monomer. In the above example, dehydration condensation with formaldehyde CH ₂ O is used, and the monomer is polymerized via the methylene group —CH ₂ —, but the other party of the condensation reaction is arbitrary.

Bisphenol S when X is SO ₂ group, bisphenol A when X is —C (CH ₃ ) ₂ —, bisphenol F when X is —CH ₂ —, and bisphenol S are used in the examples. Even if bisphenol A or bisphenol F is used, the result is the same, or the type of the formula (1) or the type of the formula (2) may be used. The molecular weight of the bisphenol-based condensate is arbitrary, for example, about 4000 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 substituted with an appropriate cation such as Na ⁺ ion, particularly an alkali metal ion, in the negative electrode active material. Furthermore, the -RSO ₃ H group, -R'SO ₃ H group, -CH ₂ -group are located, for example, in the ortho position with respect to the -OH group of the phenyl group (Ph), and the bisphenol monomer is the dehydrating condensation partner- They are connected to each other through a CH ₂ -group. Many commercially available bisphenol-based condensates have two sulfonic acid groups per monomer, but the number of sulfonic acid groups per monomer is arbitrary.

The chemical formula of polyacrylic acid is-(CH ₂ = CHCOOH) _-n , and polymethacrylic acid is
_{- (CHCH 3 = CHCOOH) -} n, the polymaleic acid - a _n - (CHCOOH = CHCOOH). Since the electrolytic solution of the lead storage battery is acidic, these compounds exist mainly in an acid form that is insoluble in water, but may exist as a salt such as an alkali metal salt. The polycarboxylic acid may be a copolymer with another olefin.

  In the present invention, the presence of both the bisphenol-based condensate and the polycarboxylic acid compound in the negative electrode active material allows the carbon black concentration in the electrolyte to be 3 massppm even if the negative electrode active material contains 0.5 mass% or more of carbon black. You can: However, if carbon black is contained in an amount exceeding 2.5 mass%, it is difficult to make the carbon black concentration in the electrolytic solution 3 mass ppm or less. Therefore, the carbon black content in the negative electrode active material is 2.5 mass% or less.

As shown in Table 1, by containing a polycarboxylic acid compound in the negative electrode active material, the carbon black concentration in the electrolytic solution can be reduced to, for example, a fraction. In addition to the polycarboxylic acid compound, the concentration of carbon black in the electrolytic solution can be further reduced to 3 mass ppm or less by including a water-soluble polymer composed of a bisphenol-based condensate. In addition, even if it contains the water-soluble polymer which consists of a bisphenol-type condensate independently, the effect of reducing the density | concentration of carbon black in electrolyte solution is not seen. A water-soluble polymer composed of a bisphenol-based condensate may be simply referred to as a bisphenol-based condensate hereinafter. From these phenomena, the inventor
・ The polycarboxylic acid compound, which is a fibrous molecule, captures carbon black and suppresses the outflow from the pores of the negative electrode active material,
-It was speculated that the water-soluble polymer composed of the bisphenol-based condensate had some interaction with the polycarboxylic acid compound to improve the carbon black capturing ability. Moreover, even if the bisphenol-based condensate is changed to lignin sulfonic acid, a weak effect is seen although it is the same type.

  The present invention further provides a liquid lead-acid battery with improved cycle life performance in a state of insufficient charge (PSOC) and excellent low-temperature high-rate discharge performance and regenerative charge acceptance performance. The improvement in cycle life performance, low-temperature high-rate discharge performance, and regenerative charge acceptance performance is an effect of a combination of 0.5 mass% to 2.5 mass% carbon black, a bisphenol-based condensate, and a polycarboxylic acid compound.

  Preferably, the negative electrode active material contains 0.1 mass% or more and 0.9 mass% or less of a water-soluble polymer composed of a bisphenol-based condensate per 100 mass% of spongy lead in a chemically formed state. In this way, the carbon black concentration in the electrolytic solution can be particularly lowered. Further, the negative electrode active material contains 0.01 mass% or more and 0.3 mass% or less of a polycarboxylic acid compound per 100 mass% of spongy lead in the already formed state. The carbon black concentration in the electrolytic solution can be made particularly low at 0.01 mass% or more, and when 0.3 mass% is exceeded, the regenerative charge acceptance performance decreases.

  Preferably, the negative electrode active material contains 1.0 mass% to 2.5 mass% of carbon black per 100 mass% of spongy lead, and the durability performance under PSOC is particularly improved when the carbon black is 1.0 mass% or more. Although the kind of polycarboxylic acid compound is arbitrary, salts such as polyacrylic acid or alkali metal salts of polyacrylic acid are easily available as industrial materials and are preferable.

  The liquid lead-acid battery of the present invention can be used for any application, but is particularly suitable for an idling stop vehicle and a charge control vehicle. Here, the idling stop vehicle refers to an automobile that stops the engine during idling and operates electrical components with the power of the lead storage battery, and restarts the engine with the power of the lead storage battery when starting from idling. The charge control vehicle refers to an automobile that operates an alternator only when the charge rate of the lead storage battery is low, and operates the electrical component by the power of the lead storage battery without charging the lead storage battery when the charge rate is high. Since the lead acid battery of the present invention has less turbidity in the electrolyte, it can be easily determined whether or not replenishment is necessary, and is excellent in low-temperature high-rate discharge performance, regenerative charge acceptance performance, and durability performance in an insufficiently charged state. It exhibits particularly high performance in idling stop vehicles and charge control vehicles.

Manufacturing process diagram of negative electrode active material paste in Example A characteristic diagram showing the content of polyacrylic acid in the negative electrode active material, the carbon concentration in the electrolyte, the low-temperature high-rate discharge performance, the regenerative charge acceptance performance, and the durability performance under PSOC. The bisphenol condensate content is 0.5mass%, carbon black content fixed at 1.5mass% A characteristic diagram showing the content of bisphenol-based condensate in the negative electrode active material, carbon concentration in the electrolyte, low-temperature high-rate discharge performance, regenerative charge acceptance performance, and durability performance under PSOC, polyacrylic acid content is 0.1mass%, carbon black content fixed at 1.5mass%

  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.

  FIG. 1 shows a production process of a negative electrode active material paste, and hereinafter, the amount of additive to the negative electrode active material is shown as a content per 100 mass% of spongy lead in the formed negative electrode active material. Polyacrylic acid was dissolved in water, and then carbon black composed of acetylene black was kneaded with an aqueous solution of polyacrylic acid. Instead of acetylene black, other carbon blacks such as oil furnace black and ketjen black may be used. Instead of polyacrylic acid, polymethacrylic acid, polymaleic acid or the like may be used, and the number of carboxy groups per molecular weight may be reduced by making these polymers a copolymer with olefin. The polycarboxylic acid is dispersed in water as an acid, but may be dissolved in water in the form of a salt such as sodium salt, potassium salt or lithium salt.

  An aqueous solution of carbon black and polyacrylic acid, a condensate of bisphenol S as a dispersing agent (molecular weight of about 100,000), and 0.6 mass% Ba sulfate for 100 mass% sponge-like lead and 100 mass% sponge-like lead As a reinforcing agent, for example, 0.1 mass% 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 were added to the carbon paste and kneaded to obtain a negative electrode active material paste. The type and production method of the lead powder is arbitrary, and the order of kneading the carbon black, the aqueous solution of polyacrylic acid and the bisphenol-based condensate is arbitrary. It is preferable to knead.

  As a conventional example and a comparative example for the above negative electrode active material, those that do not add polyacrylic acid, those that do not add bisphenol-based condensate, and lignin sulfonic acid together with Ba sulfate and synthetic fibers instead of bisphenol-based condensate Then, a material kneaded with carbon black or the like before kneading with lead powder was prepared. The amount of carbon black was changed in the range of 0.3 mass% to 3 mass%, the bisphenol-based condensate was changed in the range of 0.05 mass% to 1.0 mass%, and the polyacrylic acid was changed in the range of 0.005 mass% to 0.4 mass%.

  A positive electrode active material paste was prepared by adding 0.1 mass% of a reinforcing fiber synthetic fiber to 100 kg of lead powder, and adding water and sulfuric acid.

  The negative electrode active material paste was filled in an expandable negative electrode grid with a Pb—Ca—Sn alloy system, and aged and dried 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 into an expandable positive electrode grid using a Pb—Ca—Sn alloy system, and aged and dried 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.

  The negative electrode plate was wrapped with a microporous polyethylene separator, and two positive electrode plates in parallel and one negative electrode plate therebetween were set in the battery case for evaluation of the turbidity of the electrolyte and the initial performance. For evaluation of durability performance, eight parallel negative electrode plates (wrapped with a polyethylene separator) and seven parallel positive electrode plates were set in a battery case. After pouring dilute sulfuric acid into the battery case as an electrolyte, the battery was formed into a liquid lead-acid battery (electrolyte specific gravity at 1.85) at 20 ° C. The composition and performance of the liquid lead acid battery are shown in Table 1, and each liquid lead acid battery is the same except for the negative electrode active material.

  Create a standard sample in which acetylene black is dispersed in the electrolyte at a concentration of 1.5 massppm to 300 massppm, compare the turbidity of the electrolyte 30 minutes after conversion with the turbidity of the standard sample, and each liquid lead-acid battery The acetylene black content in the electrolyte solution was determined. If the carbon black content in the electrolyte is 3 massppm, it does not hinder the visual recognition of the liquid level, but if it exceeds 6 massppm, the visual recognition becomes difficult.

  As the 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 in an environment where the room temperature was −15 ° C. was measured. In addition, as a regenerative charge acceptance performance, a 90% charged storage battery is placed in a room at 25 ° C and charged at a constant voltage of 2.4V for 10 seconds with a maximum charging current of 12.5A. The amount of electricity (A -S unit) was measured. In order to evaluate the durability performance in a state of insufficient charging, a cycle consisting of discharging at 50 A for 60 seconds and charging at a constant voltage of 2.33 V for 60 seconds with a charging current of up to 50 A is repeated, and the terminal voltage of the storage battery is discharged. Sometimes the number of cycles to below 1.0V was measured. This cycle number represents the durability performance in a state where charging is insufficient.

  The measurement results (average values for each of the three lead storage batteries) are shown in Table 1, and the additive to the negative electrode active material is shown in mass% units where the amount of spongy lead in the negative electrode active material is 100 mass%. Lignin represents lignin sulfonic acid, and the carbon black concentration (mass ppm unit) in the electrolytic solution is a value determined by the above colorimetric method. In the determination, the carbon black concentration in the electrolyte was 3 massppm or less, and the initial performance was that the low temperature high-rate discharge performance and the regenerative charge acceptance performance were both better than the conventional example. FIG. 2 shows the influence of the polyacrylic acid content. In FIG. 2, the bisphenol condensate content is fixed at 0.5 mass% and the carbon black content is fixed at 1.5 mass%. FIG. 3 shows the influence of the content of the bisphenol-based condensate. In FIG. 3, the polyacrylic acid content is fixed at 0.1 mass% and the carbon black content is fixed at 1.5 mass%.

  As is apparent from Table 1, the turbidity of the electrolyte increased rapidly when the carbon black content was increased without adding bisphenol-based condensate or polyacrylic acid. Here, for example, when 0.1 mass% polyacrylic acid was added, the turbidity decreased to, for example, 1/5, but the carbon black concentration exceeded 3 massppm. Moreover, even if only the bisphenol-based condensate was added, the turbidity of the electrolytic solution could not be reduced. In addition, from experiments conducted separately, it was confirmed that a carboxy group in a water-soluble polymer such as polycarboxylic acid is necessary for suppressing the outflow of carbon black. When both polyacrylic acid and a bisphenol-based condensate were contained, the turbidity of the electrolytic solution was further reduced, and for example, the carbon black content in the electrolytic solution could be set to 1 massppm to 3 massppm. Even if lignin is used in combination with polyacrylic acid instead of the bisphenol-based condensate, the turbidity of the electrolyte can be reduced, but it is not as effective as the bisphenol-based condensate. Furthermore, high durability performance was obtained with a carbon black content of 1.5 mass%, and it was the same even when the content was increased to 2.5 mass%.

  As shown in FIG. 2, by adding 0.01 mass% or more of polyacrylic acid in addition to the bisphenol-based condensate, the carbon black concentration in the electrolyte can be reduced to 3 massppm or less, but if it exceeds 0.3 mass%, regeneration is performed. Charge acceptance performance has declined. Therefore, the polycarboxylic acid content is set to 0.01 mass% or more and 0.3 mass% or less.

  As shown in FIG. 3, in addition to polyacrylic acid, the addition of 0.1 mass% or more of a bisphenol-based condensate can reduce the carbon black concentration in the electrolyte to 3 massppm or less, which is much more effective than lignin. It was. Inclusion of a bisphenol-based condensate with polyacrylic acid improved both low-temperature high-rate discharge performance and charge acceptance performance, and contributed to improved durability performance. However, if 1 mass% of the bisphenol condensate is contained, the turbidity of the electrolyte increases, so the bisphenol condensate is contained in the range of 0.1 mass% to 0.9 mass%.

As described above, in the embodiment,
・ By keeping the turbidity of the electrolyte below 3 massppm, the visibility of the liquid level is maintained,
・ Keep low-temperature high-rate discharge performance and regenerative charge acceptance performance at or above the conventional level,
・ In addition, durability performance under insufficient charging conditions can be improved.

Claims (4)

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, per 100 mass% of the spongy lead in a chemically formed state,
With carbon black 0.5mass% or more and 2.5mass% or less,
A water-soluble polymer comprising a bisphenol-based condensate having a sulfonic acid group as a substituent;
Containing at least one polycarboxylic acid compound of the group consisting of polyacrylic acid, polymethacrylic acid, and polymaleic acid and salts thereof;
In addition, the electrolytic solution has a carbon black concentration of 3 mass ppm or less in the already formed state.   The negative electrode active material contains 100 mass% of the water-soluble polymer per 100 mass% of the spongy lead in a formed state, and contains 0.1 mass% or more and 0.9 mass% or less of the water-soluble polymer, and 0.01 mass% or more and 0.3 mass% or less of the polycarboxylic acid compound. The liquid lead-acid battery according to claim 1, wherein:   The negative electrode active material contains 1.0 mass% to 2.5 mass% of the carbon black per 100 mass% of the spongy lead, and the polycarboxylic acid compound is polyacrylic acid or a salt of polyacrylic acid. The liquid lead-acid battery according to claim 1 or 2.   The liquid lead-acid battery according to any one of claims 1 to 3, wherein the liquid lead-acid battery is for an idling stop vehicle or a charge control vehicle.

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