JP2018018800A - Lead-acid battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve life performance of a lead-acid battery.SOLUTION: A lead-acid battery 1 includes a negative electrode plate 2, a positive electrode plate 3, a separator 4 interposed between the negative electrode plate 2 and the positive electrode plate 3, and an electrolyte. The negative electrode plate 2 includes a negative electrode grid and a negative electrode material. The negative electrode material contains an organic shrink-proofing agent containing a sulfur element. The content of the sulfur element in the organic shrink-proofing agent is more than 3,000 μmol/g and 9,000 μmol/g or less. The separator 4 includes a nonwoven fabric containing glass fibers and silica particles adhering to the glass fibers. The average particle diameter of the silica particles is 1-10 μm.SELECTED DRAWING: Figure 2B

Description

  The present invention relates to a lead-acid battery.

  Lead-acid batteries are used in various applications in addition to in-vehicle and industrial applications. The lead acid battery includes a negative electrode plate, a positive electrode plate, and an electrolytic solution. A separator is disposed between the negative electrode plate and the positive electrode plate. As the separator, a glass fiber nonwoven fabric or the like is used. The negative electrode plate includes a negative electrode current collector and a negative electrode material.

  The negative electrode material contains an active material (lead or lead sulfate) that develops capacity by an oxidation-reduction reaction. In the negative electrode plate, the lead sulfate reduction reaction proceeds during charging, but lead sulfate is difficult to be reduced to spongy lead. Therefore, sulfation in which lead sulfate accumulates and lead sulfate crystals grow gradually proceeds, and the life performance of the lead storage battery decreases. For the purpose of suppressing the accumulation of lead sulfate, an anti-shrink agent (expander) is added to the negative electrode plate. Among these, the shrinkage-preventing agent derived from the organic substance is referred to as an organic shrinkage-preventing agent.

  In a stationary lead-acid battery, conventionally, a natural product-derived lignin or lignosulfonic acid is added to the negative electrode as an organic shrinking agent, and a glass fiber nonwoven fabric is used as a separator.

  For lead-acid batteries, the use of synthetic organic shrinkage agents has also been proposed. Patent Document 1 teaches the use of an organic shrunk agent having a sulfur element content of 4000 to 6000 μmol / g from the viewpoint of low-temperature high-rate discharge performance.

  Patent Document 2 teaches that a bisphenol A / sodium aminobenzenesulfonate / formaldehyde condensate having a sulfur content of 6 to 11% by mass in the compound is added to the negative electrode plate. In Patent Document 2, it is proposed to use a nonwoven fabric made of glass fiber, synthetic pulp, and silica powder in water as a separator for a lead storage battery.

International Publication No. 2015/181865 Pamphlet International Publication No. 2012/157311 Pamphlet

  In a lead-acid battery, even when natural lignin or a synthetic organic anti-shrink agent is combined with a glass fiber nonwoven fabric separator, it is difficult to suppress the accumulation of lead sulfate, and sufficient life performance cannot be obtained. In addition, part of the organic shrinkage agent added to the negative electrode plate tends to elute into the electrolyte solution and soften the positive electrode material. When the positive electrode material is softened, the durability of the positive electrode plate is lowered, and the positive electrode material is easily dropped from the positive electrode current collector. Such deterioration of the positive electrode plate decreases the life performance of the lead storage battery.

One aspect of the present invention includes a negative electrode plate, a positive electrode plate, a separator interposed between the negative electrode plate and the positive electrode plate, and an electrolyte.
The negative electrode plate includes a negative electrode current collector and a negative electrode material,
The negative electrode material includes an organic shrinking agent containing sulfur element,
The content of the sulfur element in the organic shrinkage agent is more than 3000 μmol / g and not more than 9000 μmol / g,
The separator includes a nonwoven fabric containing glass fibers and silica particles attached to the glass fibers,
The average particle diameter of the said silica particle is related with a lead acid battery which is 1-10 micrometers.

  According to the present invention, the life performance of a lead storage battery can be improved.

It is a perspective view showing typically the state where the lid of the lead acid battery concerning one side of the present invention was removed. It is a front view of the lead acid battery of FIG. It is an arrow directional cross-sectional view by the IIB-IIB line | wire of the lead acid battery of FIG. 2A. It is a graph which shows the relationship between content of the elemental sulfur of the organic preshrink agent when a separator contains a silica particle, and the life cycle of a lead acid battery. It is a graph which shows the relationship between the average particle diameter of the silica particle in a separator, and the lifetime cycle of lead acid battery. It is a graph which shows the relationship between content of the sulfur element of the organic shrinking agent when a separator contains a silica particle, and the case where it does not contain, and the elution amount of an organic shrinking agent. It is a graph which shows the relationship between content of the sulfur element of an organic shrinking agent in case a separator does not contain a silica particle, and the specific resistance of a negative electrode material. It is a graph which shows the relationship between content of the elemental sulfur of the organic preshrink agent in case a separator does not contain a silica particle, and the accumulation | storage amount of the lead sulfate in the lower part of a negative electrode.

  A lead storage battery according to one aspect of the present invention includes a negative electrode plate, a positive electrode plate, a separator interposed between the negative electrode plate and the positive electrode plate, and an electrolytic solution. The negative electrode plate includes a negative electrode current collector and a negative electrode material. The negative electrode material contains an organic shrinkage agent containing sulfur element, and the content of the sulfur element in the organic shrinkage agent is more than 3000 μmol / g and not more than 9000 μmol / g. The separator includes a nonwoven fabric including glass fibers and silica particles attached to the glass fibers. The average particle diameter of the silica particles is 1 to 10 μm.

  Conventionally, in stationary lead-acid batteries, lignin or lignosulfonic acid derived from natural products (hereinafter referred to as lignin) is used as an organic shrinking agent, and a glass fiber nonwoven fabric is used as a separator. The content of sulfur element contained in lignin is usually 500 to 600 μmol / g. However, it is difficult to sufficiently suppress the accumulation of lead sulfate in the negative electrode plate. Accumulation of lead sulfate because sulfate ions are generated near the electrode plate during charging, and a sulfuric acid solution with a high specific gravity is partially generated, so that the sulfuric acid solution with a high specific gravity tends to settle and stay in the lower part of the battery case. Is particularly prominent in the lower region of the negative electrode plate. In addition, the use of an organic shrunk agent having a content of elemental sulfur exceeding 3000 μmol / g has been studied. However, when such an organic shrunk agent having a large sulfur element content is added to the negative electrode plate, the elution of the organic shrunk agent from the negative electrode plate becomes significant, and the positive electrode material is softened by the action of the eluted organic shrunk agent. To do. For this reason, it has been difficult for conventional lead-acid batteries to obtain sufficient life performance due to accumulation of lead sulfate in the lower region of the negative electrode plate or softening of the positive electrode material.

  On the other hand, in the lead storage battery according to one aspect of the present invention, the sulfur content is over 3000 μmol / g and not more than 9000 μmol / g, and the average particle diameter adhered to the glass fiber and glass fiber. And a separator including a nonwoven fabric containing 1 to 10 μm silica particles. By such a combination, accumulation of lead sulfate in the lower region of the negative electrode plate is suppressed. Moreover, although the organic shrinkage | condensation agent whose sulfur content exceeds 3000 micromol / g and is 9000 micromol / g or less is used, elution of the organic shrinkage agent from a negative electrode plate is suppressed, and, thereby, softening of positive electrode material is also suppressed. The Therefore, life performance can be improved.

  Such an effect is considered to be due to the fact that the separator contains silica particles having the above average particle diameter, so that the electrolyte is appropriately gelled around the separator and the fluidity of the electrolyte is lowered. . When the fluidity of the electrolyte decreases, sedimentation of the sulfuric acid solution with a high specific gravity is suppressed, elution of the organic shrinkage agent from the negative electrode plate is suppressed, and movement of the organic shrinkage agent is suppressed even if the organic shrinkage agent is eluted. Is done. Moreover, in the separator, since the silica particles have entered between the glass fibers, the movement of the glass fibers is suppressed, and the strength of the separator is improved. It is thought that the elution of the organic anti-shrink agent from the negative electrode plate is also suppressed by such an improvement in separator strength.

  When the average particle diameter of the silica particles contained in the separator is less than 1 μm, the internal resistance of the lead-acid battery increases and the life performance decreases. When the average particle diameter of the silica particles exceeds 10 μm, the effect of lowering the fluidity of the electrolytic solution is reduced, and the life performance is impaired because it becomes impossible to suppress the softening or dropping of the positive electrode material. From the viewpoint of easily obtaining high life performance, the average particle size of the silica particles is preferably 1 to 5 μm, and more preferably 1 to 4 μm.

  The average particle diameter of the silica particles can be determined, for example, by arbitrarily selecting 10 or more silica particles in an enlarged photograph of the separator and averaging the particle diameters of the selected particles. The particle diameter of the silica particles is a diameter of an equivalent circle having the same area as the projected area of the silica particles that can be confirmed by an enlarged photograph.

The organic shrunk agent used in the lead storage battery according to the present embodiment contains elemental sulfur at a rate exceeding 3000 μmol / g and not exceeding 9000 μmol / g. From the viewpoint of further improving the life characteristics, the content of the elemental sulfur in the organic shrinking agent is preferably 3500 to 9000 μmol / g, more preferably 4000 to 9000 μmol / g, and 5000 to 9000 μmol / g or 5000 to 8000 μmol / g. Particularly preferred.
In addition, the content of the elemental sulfur in the organic shrinking agent being X μmol / g means that the content of the elemental sulfur contained in 1 g of the organic shrinking agent is X μmol.

  The lead acid battery according to one aspect of the present invention is particularly suitable for a control valve type (sealed) lead acid battery. The lead storage battery according to the present embodiment can be used, for example, as a lead storage battery for automobiles, a lead storage battery for stationary uninterruptible power supplies, or a lead storage battery for industrial vehicles such as forklifts.

The density of the negative electrode material is, for example, 2.5 to 5 g / cm ³ . From the viewpoint of obtaining higher life performance, the density of the negative electrode material is preferably 2.5 to 4.5 g / cm ³ . When the density of the negative electrode material is 2.5 to 4.5 g / cm ³ , high life performance is easily obtained when an organic shrinkage agent having a sulfur element content of 6000 μmol / g or more is used. Further, from the viewpoint of life performance, when the content of the elemental sulfur in the organic shrinkage agent exceeds 3000 μmol / g (preferably 4000 μmol / g or more), the density of the negative electrode material is 3.5 to 4.5 g. / Cm ³ is preferable, and when the content of the elemental sulfur in the organic anti-shrink agent is 5000 μmol / g or more, it is preferably 3.0 to 4.5 g / cm ³ . When the density of the negative electrode material is 2.5 to 3.5 g / cm ³ , it is advantageous from the viewpoint of weight reduction, and the sulfur element content is 6000 μmol / g or more (preferably 7000 μmol / g). When the above organic shrinkage agent is used, the effect of suppressing the specific resistance of the negative electrode material and the accumulation of lead sulfate in the negative electrode plate becomes remarkable.

Hereinafter, the lead storage battery according to one aspect of the present invention will be described for each major component, but the present invention is not limited to the following embodiments.
(Negative electrode plate)
The negative electrode plate of the lead storage battery is composed of a negative electrode current collector and a negative electrode material. The negative electrode material is obtained by removing the negative electrode current collector from the negative electrode plate. The negative electrode current collector may be formed by casting lead (Pb) or a lead alloy, or may be formed by processing a lead or lead alloy sheet. Examples of the processing method include expanding processing and punching processing.

  The lead alloy used for the current collector may be any of a Pb—Sb alloy, a Pb—Ca alloy, and a Pb—Ca—Sn alloy. These lead or lead alloy may further contain at least one selected from the group consisting of Ba, Ag, Al, Bi, As, Se, Cu and the like as an additive element. The negative electrode current collector may have a plurality of lead alloy layers having different compositions.

  The negative electrode material has a predetermined content of a negative electrode active material (lead or lead sulfate) that develops capacity by an oxidation-reduction reaction and an organic shrunk agent that contains more than 3000 μmol / g and no more than 9000 μmo / g of sulfur element. Including. The negative electrode material may further contain a carbonaceous material such as carbon black, barium sulfate, and the like, and may contain other additives as necessary.

  The negative electrode active material in the charged state is spongy lead, but the unformed negative electrode plate is usually produced using lead powder.

  The organic shrunk agent is an organic polymer containing a sulfur element, and generally contains a plurality of aromatic rings in the molecule and a sulfur element as a sulfur-containing group. Among the sulfur-containing groups, a sulfonic acid group or a sulfonyl group which is a stable form is preferable. The sulfonic acid group may exist in an acid form, or may exist in a salt form such as a Na salt.

As a specific example of the organic shrinking agent, a condensate of a compound having a sulfur-containing group and an aromatic ring with formaldehyde is preferable. The compound may have a plurality of aromatic rings. Examples of the aromatic ring include a benzene ring and a naphthalene ring. When the compound having an aromatic ring has a plurality of aromatic rings, the plurality of aromatic rings may be linked by a direct bond or a linking group (for example, an alkylene group, a sulfone group, etc.). Examples of such a structure include biphenyl, bisphenylalkane, and bisphenylsulfone. As a compound which has an aromatic ring, the compound which has said aromatic ring and a hydroxyl group and / or an amino group is mentioned, for example. The hydroxy group or amino group may be directly bonded to the aromatic ring, or may be bonded as an alkyl chain having a hydroxy group or an amino group. As the compound having an aromatic ring, a bisphenol compound, a hydroxybiphenyl compound, a hydroxynaphthalene compound, a phenol compound, or the like is preferable. The compound having an aromatic ring may further have a substituent. The organic shrunk agent may contain one kind of residues of these compounds or plural kinds. As the bisphenol compound, bisphenol A, bisphenol S, bisphenol F and the like are preferable. Among them, bisphenol S is a sulfonyl group (-SO ₂ -) because they have, it is easy to increase the content of the sulfur element. The condensate of the bisphenol compound is suitable for a lead-acid battery that is placed in a temperature environment higher than normal temperature because the starting performance at low temperature is not impaired even if it experiences an environment higher than normal temperature.

  The sulfur-containing group may be directly bonded to the aromatic ring contained in the compound, for example, may be bonded to the aromatic ring as an alkyl chain having a sulfur-containing group. Further, for example, a monocyclic aromatic compound such as aminobenzenesulfonic acid or alkylaminobenzenesulfonic acid may be condensed with formaldehyde together with the compound having the aromatic ring.

  Condensates of N, N ′-(sulfonyldi-4,1-phenylene) bis (1,2,3,4-tetrahydro-6-methyl-2,4-dioxopyrimidine-5-sulfonamide) and the like are organic. It may be used as an anti-shrink agent.

  If the content of the organic shrunk agent contained in the negative electrode material is within a general range, the action of the organic shrunk agent does not greatly influence. The content of the organic shrinking agent contained in the negative electrode material is, for example, preferably 0.01% by mass or more, more preferably 0.02% by mass or more, still more preferably 0.05% by mass or more, while 1.0% % By mass or less is preferred, 0.8% by mass or less is more preferred, and 0.3% by mass or less is still more preferred. Here, the content of the organic shrinking agent contained in the negative electrode material is a content in the negative electrode material collected by a method described later from a lead-acid battery in a fully formed state.

  The negative electrode plate can be formed by filling a negative electrode current collector with a negative electrode paste, aging and drying to produce an unformed negative electrode plate, and then forming an unformed negative electrode plate. The negative electrode paste is prepared by adding water and sulfuric acid to a lead powder, an organic shrinking agent, and various additives as necessary, and kneading them. In the aging step, it is preferable to age the unformed negative electrode plate at a temperature higher than room temperature and high humidity.

  The chemical conversion can be performed by charging the electrode plate group in a state in which the electrode plate group including the unformed negative electrode plate is immersed in an electrolytic solution containing sulfuric acid in the battery case of the lead storage battery. However, the chemical conversion may be performed before the assembly of the lead storage battery or the electrode plate group. Sponge-like lead is generated by chemical conversion.

(Positive electrode)
As the positive electrode plate of the lead storage battery, it is preferable to use a paste-type positive electrode plate.
The paste type positive electrode plate includes a positive electrode current collector and a positive electrode material. The positive electrode material is held by the positive electrode current collector. The positive electrode current collector may be formed in the same manner as the negative electrode current collector, and can be formed by casting lead or a lead alloy or processing a lead or lead alloy sheet.

The lead alloy used for the positive electrode current collector is preferably a Pb—Ca alloy or a Pb—Ca—Sn alloy in terms of corrosion resistance and mechanical strength. The positive electrode current collector may have lead alloy layers having different compositions, and a plurality of lead alloy layers may be provided.
The positive electrode material includes a positive electrode active material (lead dioxide or lead sulfate) that develops capacity by an oxidation-reduction reaction. The positive electrode material may contain other additives as necessary.

  The unformed paste type positive electrode plate is obtained by filling the positive electrode current collector with the positive electrode paste, aging and drying in the same manner as the negative electrode plate. Thereafter, an unformed positive electrode plate is formed. The positive electrode paste is prepared by kneading lead powder, additives, water, and sulfuric acid.

(Separator)
The nonwoven fabric constituting the separator is a mat in which glass fibers are not woven, and silica particles having an average particle diameter of 1 to 10 μm are attached to the glass fibers. Such a nonwoven fabric can be obtained, for example, by papermaking (wet papermaking or the like) of glass fibers and silica particles.

  The average fiber diameter of the glass fibers is preferably 0.1 μm or more and 25 μm or less, for example. As will be described later, the average fiber diameter can be obtained from an enlarged photograph of the selected fibers by arbitrarily selecting 10 or more fibers. The glass fiber is not limited to a single fiber diameter but may be a mixture of a plurality of fiber diameters (for example, 1 μm and 10 μm).

  Said nonwoven fabric may contain the fiber material insoluble in electrolyte solution other than glass fiber. As fiber materials other than glass fibers, polymer fibers (polyolefin fibers, acrylic fibers, polyester fibers such as polyethylene terephthalate fibers), pulp fibers, and the like can be used. For example, it is preferable that 60% by mass or more of the separator is formed of a fiber material. It is preferable that the ratio of the glass fiber to the fiber material which comprises a separator is 60 mass% or more. Moreover, the nonwoven fabric may contain inorganic powders (for example, glass powder, diatomaceous earth) other than silica particles.

  The proportion of silica particles having an average particle diameter of 1 to 10 μm in the separator is, for example, 1 to 50% by mass, and 1 to 30% by mass is preferable from the viewpoint of easily reducing internal resistance. From the viewpoint of easily suppressing elution, 10 to 30% by mass is more preferable.

  The separator only needs to contain the above-mentioned non-woven fabric. For example, the separator may be composed of only the above-described non-woven fabric, and if necessary, a laminate of the above non-woven fabric and other non-woven fabric and / or a microporous membrane. Further, it may be a product obtained by bonding a different type or the same type of material to the above-mentioned nonwoven fabric, or a type obtained by engaging the above-mentioned non-woven fabric and a different type or the same type of material with a male or female. It is preferable to arrange the separator so that the above-mentioned nonwoven fabric is in contact with at least the main surface of the negative electrode plate. Examples of other nonwoven fabrics include polymer fibers (polyolefin fibers, acrylic fibers, polyester fibers such as polyethylene terephthalate fibers), pulp fiber nonwoven fabrics, and glass fiber nonwoven fabrics that do not contain silica particles having an average particle diameter of 1 to 10 μm. used. The microporous membrane is a porous sheet mainly composed of components other than the fiber component. For example, after extruding a composition containing a pore-forming agent (polymer powder and / or oil, etc.) into a sheet shape, It is obtained by removing to form pores. The material constituting the separator is preferably acid resistant, and the polymer component is preferably a polyolefin such as polyethylene or polypropylene.

  The thickness (total thickness) of the separator may be selected according to the size of the lead storage battery, the distance between the electrode plates, and the like, and is, for example, 0.5 to 5 mm.

(Electrolyte)
The electrolytic solution is an aqueous solution containing sulfuric acid. The specific gravity at 20 ° C. of the electrolyte in a fully charged lead storage battery after chemical conversion is, for example, 1.10 to 1.35 g / cm ³ , and preferably 1.20 to 1.35 g / cm ³ .

Next, a method for analyzing each physical property will be described.
(1) Density of negative electrode material The density of the negative electrode material means the value of the bulk density of the fully charged negative electrode material after chemical conversion, and is measured as follows. The battery after chemical conversion is fully charged and then disassembled, and the obtained negative electrode plate is washed and dried to remove the electrolyte in the negative electrode plate. Next, the negative electrode material is separated from the negative electrode plate to obtain an unground measurement sample. After putting the sample into the measurement container and evacuating it, filling the mercury with a pressure of 0.5 to 0.55 psia, measuring the bulk volume of the negative electrode material, and dividing the mass of the measurement sample by the bulk volume The bulk density of the negative electrode material is obtained. The volume obtained by subtracting the injection volume of mercury from the volume of the measurement container is defined as the bulk volume.

In this specification, the fully charged state of the lead acid battery means that the lead acid battery after chemical conversion is charged at a constant current and a constant voltage of 2.23 V / cell at a 5-hour rate current in an air tank at 25 ° C. In this state, charging is terminated when the charging current at that time becomes 1 mCA or less.
In the present specification, 1 CA is a current value for discharging the nominal capacity of the battery in one hour. For example, if the battery has a nominal capacity of 30 Ah, 1CA is 30 A, and 1 mCA is 30 mA.

(2) Analysis of organic shrunk agent First, a lead-acid battery in a fully charged state is disassembled after chemical conversion, the negative electrode plate is taken out, sulfuric acid is removed by washing with water, and dried. Next, a negative electrode material (initial sample) is collected from the dried negative electrode plate, and the initial sample is analyzed by the following method.

(2-1) Qualitative Analysis of Organic Shrink Agent in Negative Electrode Material The initial sample is immersed in a 1 mol / L sodium hydroxide (NaOH) aqueous solution to extract the organic shrunk agent. Next, insoluble components are removed by filtration from the extracted aqueous NaOH solution containing the organic shrinking agent, and the obtained filtrate is desalted by dialysis, then concentrated and dried. Desalting may be performed by passing the filtrate through an ion exchange membrane, or by putting the filtrate in a dialysis tube and immersing it in distilled water. Thereby, a powder sample of the organic shrinking agent is obtained.

  Infrared spectroscopic spectrum measured using a powder sample of the organic shrunk agent obtained in this way, or a powder sample dissolved in distilled water or the like, and measured with an ultraviolet-visible spectrophotometer, an ultraviolet-visible absorption spectrum, or a predetermined solvent such as heavy water The information obtained from the NMR spectrum of the obtained solution after being dissolved is used in combination to identify the type of organic anti-shrink agent.

(2-2) Content of Organic Shrinking Agent in Negative Electrode Material After obtaining a filtrate of an NaOH aqueous solution containing an organic shrinking agent in the same manner as in (2-1) above, the UV-visible absorption spectrum of the filtrate is measured. Using the spectrum intensity and a calibration curve prepared in advance, the content of the organic shrinking agent in the negative electrode material can be quantified.

  When obtaining a lead-acid battery with an unknown content of the organic shrinkage agent and measuring the content of the organic shrinkage agent, it is not possible to strictly specify the structural formula of the organic shrinkage agent. The agent may not be used. In this case, calibration is performed using an organic shrinkage agent that is extracted from the negative electrode of the battery and an organic shrinkage agent that has a similar shape in the UV-visible absorption spectrum, infrared spectrum, and NMR spectrum. By creating a line, it is possible to measure the content of the organic shrinking agent using an ultraviolet-visible absorption spectrum.

(2-3) Content of Sulfur Element in Organic Shrinkage Agent As in (2-1) above, after obtaining a powder sample of the organic shrunk agent, 0.1 g of the organic shrunk agent was obtained by the oxygen combustion flask method. The elemental sulfur is converted to sulfuric acid. At this time, an eluate in which sulfate ions are dissolved in the adsorbent is obtained by burning the powder sample in the flask containing the adsorbent. Next, the eluate is titrated with barium perchlorate using thorin as an indicator to determine the content (C1) of elemental sulfur in 0.1 g of the organic shrinking agent. Next, C1 is multiplied by 10, and the content (μmol / g) of elemental sulfur in the organic shrinkage agent per gram is calculated.

(3) Analysis of glass fiber and silica particles An already formed lead-acid battery in a fully charged state is disassembled, a separator is taken out, sulfuric acid is removed by washing with water and dried. Next, the dried separator is pulverized, and the pulverized sample is analyzed by the following method.

(3-1) Average fiber diameter of glass fiber A ground sample is observed with an optical microscope or an electron microscope, ten or more fibers whose length can be measured are selected, and an enlarged photograph thereof is taken. Next, the photograph of each fiber is image-processed, and the fiber diameter in the vicinity of the center in the fiber length direction is obtained. What is necessary is just to calculate the average of the obtained fiber diameter, and let it be the average fiber diameter of glass fiber.

(3-2) Content of Glass Fiber in Separator The mass ratio C (%) of the glass fiber in the separator can be obtained when the glass fiber can be isolated from the ground sample. At this time, the mass ratio C (%) is obtained from C (%) = 100x using, for example, the mass x (g) of the glass fiber isolated from 1 g of the ground sample.

The volume ratio Cv of the glass fiber in the separator can be obtained even when it is difficult to isolate the glass fiber from the pulverized sample. First, arbitrary cross-sectional photographs of the pulverized sample are taken at a plurality of locations, and the cross-sectional photographs are subjected to image processing, and glass fibers contained in a rectangular region having a length (L ₁ ) that is 10 times the average fiber length as one side. The area s ₁ is obtained. At this time, the ratio of s ₁ to the area (L ₁ ² ) of the rectangular region can be regarded as the volume ratio Cv of the glass fiber in the separator. The volume ratio Cv is obtained from Cv (%) = 100 s ₁ / L ₁ ² .

(3-3) Average particle diameter of silica particles First, the fibers of the glass separator are loosened by hand, and the silica particles separated from the fibers at that time are observed with an optical microscope or an electron microscope, and the silica particles can be measured. Select 10 or more and take an enlarged picture. Next, the photograph of each particle is image-processed and a particle diameter is calculated | required. The average of the obtained particle diameters may be calculated and used as the average particle diameter of the silica particles.

(3-4) Content of silica particles in separator The mass ratio D (%) of silica particles in the separator can be determined when the silica particles can be isolated from the pulverized sample. At this time, the mass ratio D (%) is obtained from D (%) = 100 y using, for example, the mass y (g) of silica particles isolated from 1 g of the ground sample.

The volume ratio Dv of the silica particles in the separator can be obtained even when it is difficult to isolate the silica particles from the pulverized sample. First, arbitrary cross-sectional photographs of the pulverized sample are taken at a plurality of locations, and the cross-sectional photographs are subjected to image processing, and silica particles contained in a rectangular region having a length (L ₂ ) that is 10 times the average particle diameter as one side. The area s ₂ is obtained. At this time, the ratio of s ₂ to the area (L ₂ ² ) of the rectangular region can be regarded as the volume ratio Dv of the silica particles in the separator. The volume ratio Dv is obtained from Dv (%) = 100 s ₂ / L ₂ ² .

FIG. 1 is a perspective view schematically showing an example in which a lid of a lead storage battery according to an embodiment of the present invention is removed. 2A is a front view of the lead storage battery of FIG. 1, and FIG. 2B is a cross-sectional view taken along the line IIB-IIB of FIG. 2A.
The lead storage battery 1 includes a battery case 10 that accommodates an electrode plate group 11 and an electrolytic solution (not shown). The electrode plate group 11 is configured by laminating a plurality of negative plates 2 and positive plates 3 with a separator 4 interposed therebetween.

  A current collecting ear portion (not shown) protruding upward is provided on each of the plurality of negative electrode plates 2. A current collecting ear (not shown) protruding upward is also provided on each upper portion of the plurality of positive electrode plates 3. And the ear | edge parts of the negative electrode plate 2 are connected and integrated by the strap 5a for negative electrodes. Similarly, the ears of the positive electrode plate 3 are connected and integrated by the positive strap 5b. The negative pole 6a is fixed to the negative strap 5a, and the positive pole 6b is fixed to the positive strap 5b.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
(1) Preparation of negative electrode plate Lead powder, water, dilute sulfuric acid, barium sulfate, carbon black, and a predetermined amount of organic shrinkage agent were mixed to obtain a negative electrode paste. The negative electrode paste was filled in a mesh part of a cast lattice made of a Pb—Ca—Sn alloy, aged and dried to obtain an unformed negative electrode plate.

The amount of the organic shrunk agent is adjusted so that the content (A (% by weight)) of the organic shrunk agent is 0.15% by weight with respect to 100% by weight of the negative electrode material after being fully charged in the existing chemical. And added to the negative electrode paste. Further, when preparing the negative electrode paste, the amount of water and dilute sulfuric acid added to the negative electrode paste was adjusted so that the density of the negative electrode material after being formed and fully charged was 2.5 g / cm ³ .

  In addition, the density of the negative electrode material was obtained using the measurement sample recovered by fully disassembling the battery after chemical conversion in accordance with the procedure described above. The battery was fully charged according to the procedure described above. The density of the negative electrode material was measured by the method described above using an automatic porosimeter (Autopore IV9505) manufactured by Shimadzu Corporation.

As the organic shrinking agent, a condensate of bisphenol compound having sulfonic acid group introduced with formaldehyde was used. Here, the amount of the sulfonic acid group to be introduced was controlled so that the content of the elemental sulfur in the organic shrinking agent was 4000 μmol / g.
In addition, about elemental sulfur content (micromol / g) in an organic contraction agent, there must be no difference in the value measured before disassembling a lead storage battery and extracting an organic contraction agent before preparing a negative electrode material. It was confirmed. Therefore, hereinafter, as the sulfur element content in the organic shrinkage agent described in the examples and comparative examples, values obtained for the organic shrinkage agent before preparing the negative electrode material are described.

(2) Production of positive electrode plate A positive electrode paste was produced by kneading lead powder, water, and sulfuric acid. The positive electrode paste was filled in a mesh portion of a cast lattice made of a Pb—Ca—Sn alloy, and aged and dried to obtain an unformed positive electrode plate.

(3) Production of lead acid battery Using four unformed negative plates and three unformed positive plates, a separator is interposed between the negative plates and the positive plates, and the negative plates and the positive plates are alternately laminated. Thus, an electrode plate group was formed. As the separator, a nonwoven fabric in which glass fibers and silica particles (average particle diameter of 3 μm) were mixed by wet papermaking was used.

  The mass ratio C of the glass fibers and the mass ratio D of the silica particles in the separator were 80 mass% and 20 mass%, respectively. When the glass fibers and silica particles in the separator were observed with an electron microscope, the average fiber diameter of the glass fibers was 0.7 μm, and the average particle diameter of the silica particles was 3 μm.

  The electrode plate group was accommodated in a polypropylene battery case, an electrolyte solution was injected, chemical conversion was performed in the battery case, and a control valve type lead storage battery was assembled. The output of the lead acid battery is 2V, and the nominal capacity is 500 Ah (5 hour rate).

  In addition, about the produced lead acid battery, content (A (mass%)) of the organic shrunk agent contained in the negative electrode material (100 mass%) taken out from the negative electrode plate was calculated | required in the procedure described above. The content of the organic shrinkage agent quantified in this way was somewhat different from the content of the organic shrinkage agent (B (mass%)) in the negative electrode material (100 mass%) prepared for the lead-acid battery. Value. Therefore, when the ratio R (= A / B) of these contents A and B is obtained in advance and the negative electrode material used for the negative electrode plate of another lead storage battery is prepared, the ratio R is used to obtain the negative electrode The content (B (mass%)) of the organic shrinking agent in the prepared negative electrode material was adjusted so that the content (A (mass%)) of the organic shrinking agent in the material became a predetermined value. In Examples and Comparative Examples, the ratio R is obtained for each sulfur element content of the organic shrinking agent used, and the negative electrode material using the organic shrinking agent having the same sulfur element content is based on the obtained ratio R. The content (B (mass%)) of the organic anti-shrink agent was adjusted.

<< Examples 2-6 and Comparative Examples 1-2 >>
The content of elemental sulfur in the organic shrinking agent is 5000 μmol / g (Example 2), 6000 μmol / g (Example 3), 7000 μmol / g (Example 4), 8000 μmol / g (Example 5), 9000 μmol / g. The amount of the sulfonic acid group introduced into the condensate of the bisphenol compound with formaldehyde was adjusted so as to be (Example 6), 2000 μmol / g (Comparative Example 1), or 3000 μmol / g (Comparative Example 2), respectively. A negative electrode plate was formed in the same manner as in Example 1 except that each of the organic shrinkage agents having the sulfur element content was used. A lead storage battery was assembled in the same manner as in Example 1 except that the obtained negative electrode plate was used.

<< Comparative Example 3 >>
As the organic shrinking agent, lignin derived from a natural product and having a sulfur element content of 600 μmol / g was used. A glass fiber nonwoven fabric was used as the separator. Except for these, a negative electrode plate was formed in the same manner as in Example 1. A lead storage battery was assembled in the same manner as in Example 1 except that the obtained negative electrode plate was used.

<< Comparative Examples 4 to 10 >>
The content of elemental sulfur in the organic shrunk agent is 2000 μmol / g (Comparative Example 4), 3000 μmol / g (Comparative Example 5), 4000 μmol / g (Comparative Example 6), 5000 μmol / g (Comparative Example 7), and 6000 μmol / g. The amount of the sulfonic acid group introduced into the condensate of bisphenol compound with formaldehyde was adjusted so as to be (Comparative Example 8), 7000 μmol / g (Comparative Example 9), or 8000 μmol / g (Comparative Example 10), respectively. The organic shrinkage | condensation agent which has content of these sulfur elements was used, respectively. Moreover, the nonwoven fabric of glass fiber was used as a separator. Except for these, a negative electrode plate was formed in the same manner as in Example 1.
A lead storage battery was assembled in the same manner as in Example 1 except that the obtained negative electrode plate was used.

<< Examples 7-12 and Comparative Examples 11-12 >>
A negative electrode plate was produced in the same manner as in Example 1 except that the amount of water and dilute sulfuric acid added to the negative electrode paste was adjusted so that the density of the formed negative electrode material was 3.5 g / cm ³ ( Example 7).

Further, the amount of water and dilute sulfuric acid added to the negative electrode paste was adjusted so that the density of the negative electrode material was 3.5 g / cm ³ . Furthermore, the content of elemental sulfur in the organic shrinking agent is 5000 μmol / g (Example 8), 6000 μmol / g (Example 9), 7000 μmol / g (Example 10), 8000 μmol / g (Example 11), 9000 μmol. / G (Example 12), 2000 μmol / g (Comparative Example 11), or 3000 μmol / g (Comparative Example 12), the amount of the sulfonic acid group introduced into the condensate of the bisphenol compound with formaldehyde was adjusted, respectively. did. Except for these, a negative electrode plate was formed in the same manner as in Example 1.
And the lead acid battery was assembled like Example 1 except having used the negative electrode plate obtained above.

<< Comparative Example 13 >>
Lignin was used as an organic shrinking agent in the same manner as in Comparative Example 3 except that the amounts of water and dilute sulfuric acid added to the negative electrode paste were adjusted so that the density of the ready-made negative electrode material was 3.5 g / cm ^3. Thus, a negative electrode plate was produced. A lead storage battery was assembled in the same manner as in Comparative Example 3 except that the obtained negative electrode plate was used.

<< Comparative Examples 14-20 >>
The amount of water and dilute sulfuric acid added to the negative electrode paste was adjusted so that the density of the ready-made negative electrode material was 3.5 g / cm ³ . The content of elemental sulfur in the organic anti-shrink agent is 2000 μmol / g (Comparative Example 14), 3000 μmol / g (Comparative Example 15), 4000 μmol / g (Comparative Example 16), 5000 μmol / g (Comparative Example 17), and 6000 μmol / g. The amount of the sulfonic acid group introduced into the condensate of the bisphenol compound with formaldehyde was adjusted so as to be (Comparative Example 18), 7000 μmol / g (Comparative Example 19), or 8000 μmol / g (Comparative Example 20), respectively. A negative electrode plate was produced in the same manner as in Comparative Examples 4 to 10 except for these. A lead storage battery was assembled in the same manner as in Comparative Example 4 except that the obtained negative electrode plate was used.

<< Examples 13 to 17 >>
A negative electrode plate was produced in the same manner as in Example 1 except that the amount of water and dilute sulfuric acid added to the negative electrode paste was adjusted so that the density of the pre-formed negative electrode material was 3.0 g / cm ³ ( Example 13).
Further, the amounts of water and dilute sulfuric acid added to the negative electrode paste were adjusted so that the density of the negative electrode material was 3.0 g / cm ³ . The content of elemental sulfur in the organic shrinking agent is 5000 μmol / g (Example 14), 6000 μmol / g (Example 15), 7000 μmol / g (Example 16), or 8000 μmol / g (Example 17). In addition, the amount of sulfonic acid group introduced into the condensate of bisphenol compound with formaldehyde was adjusted. Except for these, a negative electrode plate was formed in the same manner as in Example 1.
And the lead acid battery was assembled like Example 1 except having used the negative electrode plate obtained above.

<< Examples 18 to 22 >>
A negative electrode plate was produced in the same manner as in Example 1 except that the amount of water and dilute sulfuric acid added to the negative electrode paste was adjusted so that the density of the pre-formed negative electrode material was 4.0 g / cm ³ ( Example 18).
Further, the amount of water and dilute sulfuric acid added to the negative electrode paste was adjusted so that the density of the negative electrode material was 4.0 g / cm ³ . The content of elemental sulfur in the organic shrinking agent is 5000 μmol / g (Example 19), 6000 μmol / g (Example 20), 7000 μmol / g (Example 21), or 8000 μmol / g (Example 22). In addition, the amount of sulfonic acid group introduced into the condensate of bisphenol compound with formaldehyde was adjusted. Except for these, a negative electrode plate was formed in the same manner as in Example 1.
And the lead acid battery was assembled like Example 1 except having used the negative electrode plate obtained above.

<< Examples 23 to 27 >>
A negative electrode plate was produced in the same manner as in Example 1 except that the amount of water and dilute sulfuric acid added to the negative electrode paste was adjusted so that the density of the pre-formed negative electrode material was 4.5 g / cm ³ ( Example 23).
Further, the amount of water and dilute sulfuric acid added to the negative electrode paste was adjusted so that the density of the negative electrode material was 4.5 g / cm ³ . The content of elemental sulfur in the organic shrinking agent is 5000 μmol / g (Example 24), 6000 μmol / g (Example 25), 7000 μmol / g (Example 26), or 8000 μmol / g (Example 27). In addition, the amount of sulfonic acid group introduced into the condensate of bisphenol compound with formaldehyde was adjusted. Except for these, a negative electrode plate was formed in the same manner as in Example 1.
And the lead acid battery was assembled like Example 1 except having used the negative electrode plate obtained above.

<< Examples 28-29 and Comparative Examples 21-23 >>
The amount of water and dilute sulfuric acid added to the negative electrode paste was adjusted so that the density of the negative electrode material was 3.5 g / cm ³ . The amount of the sulfonic acid group introduced into the condensate of the bisphenol compound with formaldehyde was adjusted so that the content of elemental sulfur in the organic shrinking agent was 7000 μmol / g. The average particle diameter of the silica particles contained in the separator is 0.01 μm (Comparative Example 21), 0.1 μm (Comparative Example 22), 1 μm (Example 28), 10 μm (Example 29), or 100 μm (Comparative Example 23). changed. A negative electrode plate was produced in the same manner as in Example 1 except for the above. A lead storage battery was assembled in the same manner as in Example 1 except that the negative electrode plate obtained above was used.

[Evaluation 1]
Regarding the lead-acid batteries produced in Examples and Comparative Examples, the charge / discharge cycle test was conducted at 25 ° C. with a depth of discharge of 70%, and the cycle when the discharge end voltage at the depth of 70% discharge fell below 1.7V. The number was determined and the life cycle of the lead acid battery was evaluated.
In the charge / discharge cycle test, the battery is discharged at a current value of 0.2 CA for 3.5 hours at the time of discharge, and at the time of charge is a constant voltage of 2.42 V and a maximum current of 0.2 CA, and the charge electricity is equal to the discharge electricity quantity. The battery was charged at a constant voltage to be 102%. And equal charge was performed every 6 cycles. In the equal charge, in addition to the normal charge, charging was performed at a voltage of 2.42 V for 8 hours.

FIG. 3 shows the relationship between the content of elemental sulfur in the organic anti-shrink agent and the life cycle of the lead-acid battery in the above examples and comparative examples, when the separator contains silica particles. FIG. 3 shows data when the density of the negative electrode material is 2.5 g / cm ³ and 3.5 g / cm ³ . In the comparative example using lignin, the life cycle is low. When the content of sulfur element is 3000 μmol / g, there is almost no difference in the number of life cycles depending on whether or not silica particles are contained in the separator. When the content of elemental sulfur is 2000 μmol / g, a higher life cycle is obtained when the separator does not contain silica particles than when the separator contains silica particles. On the other hand, when the sulfur element content exceeds 3000 μmol / g, the life cycle is greatly improved when the separator contains silica particles as compared to when the silica particles are not contained.

  From FIG. 3, in the comparative example using the separator not containing silica particles, the life cycle becomes maximum when the content of sulfur element is 4000 μmol / g or 5000 μmol / g, and even if the sulfur content is further increased, the life cycle Will decline. When the content of sulfur element is 8000 μmol / g, the life cycle is lowered to the same extent as in the case of lignin. On the other hand, in the example using the separator containing silica particles, a high life cycle is obtained when the content of sulfur element exceeds 3000 μmol / g and is 9000 μmol / g or less. When the content of sulfur element is 4000 to 9000 μmol / g or 5000 to 9000 μmol / g, the life cycle is particularly high.

  Table 1 shows the results of the life cycle when the sulfur element content is 4000 to 8000 μmol / g at each density of the negative electrode material.

As shown in Table 1, even when the density of the negative electrode material is 3 g / cm ³ , 4 g / cm ³ , 4.5 g / cm ³ , a high life cycle is obtained as in the example shown in FIG. It was. The life cycle increases as the density of the negative electrode material increases.

  About the lead acid battery of Examples 28-29 and Comparative Examples 21-23, the relationship between the average particle diameter of a silica particle and a lifetime cycle was investigated. FIG. 4 is a graph showing the relationship between the average particle diameter of silica particles in the separator and the life cycle of the lead storage battery. As shown in FIG. 4, when the average particle diameter of the silica particles is 1 to 10 μm, a high life cycle of 5000 cycles or more is secured as compared with the case where the average particle diameter is smaller than 1 μm and larger than 10 μm. Have been able to.

[Evaluation 2]
Regarding the produced lead acid battery, the elution amount of the organic anti-shrink agent from the negative electrode plate was measured. Here, the negative electrode plate is taken out from the lead-acid battery at the time of 200 cycles of the heavy load life test, the content C1 of the organic shrinkage agent in the negative electrode material is measured, and the organic from the difference from the initial content C2 of the organic shrinkage agent The elution amount of the antishrink agent was calculated from the following formula.
Elution amount (%) = {1- (C1 / C2)} × 100

FIG. 5 shows the relationship between the content of sulfur element in the organic shrinking agent and the elution amount of the organic shrinking agent. FIG. 5 shows the elution amount of the organic shrinking agent when the density of the negative electrode material is 2.5 g / cm ³ and 3.5 g / cm ³ , with and without the separator containing silica particles. It was. From FIG. 5, when the content of elemental sulfur exceeds 3000 μmol / g, the elution amount of the organic shrinking agent is greater when the separator containing silica particles is used than when the separator containing no silica particles is used. Is significantly reduced.

[Evaluation 3]
With respect to the lead-acid batteries produced in Examples and Comparative Examples, a charge / discharge cycle test was performed, and the specific resistance was measured as follows at the stage where the charge at the 2000th cycle was completed.
First, the negative electrode plate was taken out from the lead storage battery, washed with water, and dried. Two current lines and two voltage lines were connected to the center positions of the upper end and the lower end of the region of the negative electrode plate where the negative electrode material was present, and a direct current was passed by the four-terminal method to measure the voltage drop. Then, the specific resistance was calculated from a calibration curve showing the relationship between the voltage drop and the specific resistance obtained by CAE analysis.

The specific resistance of the negative electrode material in each lead-acid battery is a ratio (%) where the density of the negative electrode material is 3.5 g / cm ³ and the value in the lead-acid battery of Comparative Example 13 using lignin is 100. expressed. Further, the amount of lead sulfate accumulated was expressed as a mass ratio (%) when the mass of the entire negative electrode material was taken as 100.

  In addition, at the 2000th cycle, the amount of lead sulfate accumulated in the lower part of the negative electrode plate (position 20% from the bottom of the height of the negative electrode plate) was examined. The amount of lead sulfate accumulated was determined as follows. First, the negative electrode material collected from the negative electrode plate was washed with water, dried, and pulverized. The amount of elemental sulfur contained in the pulverized product was measured using an elemental sulfur analyzer. Next, the content of elemental sulfur in lead sulfate was determined according to the following formula.

Content of elemental sulfur in lead sulfate = (mass of elemental sulfur obtained by elemental sulfur analyzer) − (mass of sample × content of organic shrinkage agent × content of sulfur element in organic shrinkage agent)
Then, the amount of elemental sulfur contained in the obtained lead sulfate was converted to the amount of lead sulfate, the lead sulfate concentration per unit mass of the sample was determined, and the amount of lead sulfate accumulated was obtained.

FIG. 6 shows the relationship between the content of sulfur element in the organic shrinking agent and the specific resistance of the negative electrode material. Further, FIG. 7 shows the relationship between the content of sulfur element in the organic shrinking agent and the amount of lead sulfate accumulated in the lower region of the negative electrode plate. 6 and 7 show data when the density of the negative electrode material is 2.5 g / cm ³ and 3.5 g / cm ³ . Usually, as the density of the negative electrode material decreases, the specific resistance increases and the amount of lead sulfate accumulation increases. However, as shown in FIGS. 6 and 7, when the content of elemental sulfur increases, the specific resistance between the negative electrode material density of 2.5 g / cm ³ and 3.5 g / cm ³ and The difference in the amount of lead sulfate accumulated is small. From these results, it can be said that the effect of a high sulfur element content becomes remarkable when the density of the negative electrode material is low. Further, from the viewpoint of suppressing the specific resistance, it is advantageous to use an organic shrinking agent having a high sulfur element content. However, when such an organic shrinking agent is used, the softening and falling off of the positive electrode tends to be remarkable. Therefore, by using silica particles having an average particle diameter of 1 to 10 μm, it is possible to suppress softening and falling off of the positive electrode and to use an organic shrunk agent having a high sulfur element content, thereby reducing specific resistance.

  The embodiment of the present invention is applicable to a control valve type lead storage battery, and is suitably used as a power source for an industrial power storage device such as an electric vehicle (forklift, etc.). It can also be used as a power source for power storage devices such as automobiles or motorcycles.

1: lead acid battery 2: negative electrode plate 3: positive electrode plate 4: separator 5a: strap for negative electrode 5b: strap for positive electrode 6a: negative electrode column 6b: positive electrode column 10: battery case 11: electrode plate group

Claims (4)

A negative electrode plate, a positive electrode plate, a separator interposed between the negative electrode plate and the positive electrode plate, and an electrolytic solution,
The negative electrode plate includes a negative electrode current collector and a negative electrode material,
The negative electrode material includes an organic shrinking agent containing sulfur element,
The content of the sulfur element in the organic shrinkage agent is more than 3000 μmol / g and not more than 9000 μmol / g,
The separator includes a nonwoven fabric containing glass fibers and silica particles attached to the glass fibers,
The lead acid battery whose average particle diameter of the said silica particle is 1-10 micrometers.   The lead acid battery according to claim 1, wherein the content of the elemental sulfur in the organic shrinking agent is 4000 to 9000 μmol / g.   The lead acid battery according to claim 1 or 2, wherein the content of the elemental sulfur in the organic shrinking agent is 5000 to 9000 µmol / g. The density of the said negative electrode material is a lead acid battery of any one of Claims 1-3 which is 2.5-4.5 g / cm < ³ >.

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