JPWO2018199242A1 - Lead storage battery - Google Patents

Abstract

A lead storage battery includes a negative electrode plate and a positive electrode plate. The negative electrode plate includes a negative electrode material containing a carbon material and barium sulfate. The carbon material includes a first carbon material having a particle diameter of 32 μm or more and a second carbon material having a particle diameter of less than 32 μm, and the second carbon material has a powder resistance R1 of the first carbon material. The ratio of the powder resistance R2 of the material: R2 / R1 is more than 15 and less than 230. The content of barium sulfate in the negative electrode material is 0.2% by mass or more and 0.7% by mass or less. The density of the negative electrode material is 3.8 g / cm3 or more. [Selection diagram] Fig. 1

Description

  The present invention relates to a lead storage battery.

Lead storage batteries are used for various purposes in addition to in-vehicle and industrial use. The lead storage battery includes a negative electrode plate, a positive electrode plate, and an electrolyte. The negative electrode plate includes a current collector and a negative electrode material. The negative electrode material includes a carbon material, barium sulfate, and the like. Patent Literature 1 proposes a negative electrode material containing graphite or carbon fiber, carbon black, and barium sulfate and having a density of 3.6 to 4.0 g / cm ³ . Patent Literature 2 proposes a negative electrode material containing barium sulfate of less than 0.6 mass% and a density higher than 3.6 g / cm ³ . Patent Document 2 describes that the carbon content of the negative electrode material is 0.2 mass% or less, and that acetylene black is used as carbon.

JP 2016-152131 A JP 2016-189260 A

  Generally, when the density of the negative electrode material is increased, the cycle life is improved. However, when forming a negative electrode plate having a high density of the negative electrode material, if carbon black is added to the negative electrode material, applicability to the current collector is reduced. In addition, depending on the composition of the negative electrode material, charging becomes difficult after deep discharge is performed, and the cycle life may be reduced.

  An object of the present invention is to improve the cycle life performance of a lead-acid battery when performing deep discharge while making a negative electrode plate easy.

One aspect of the present invention is a lead storage battery,
The lead storage battery includes a negative electrode plate and a positive electrode plate,
The negative electrode plate includes a negative electrode material containing a carbon material and barium sulfate,
The carbon material includes a first carbon material having a particle diameter of 32 μm or more, and a second carbon material having a particle diameter of less than 32 μm,
The ratio of the powder resistance R2 of the second carbon material to the powder resistance R1 of the first carbon material: R2 / R1 is more than 15 and less than 230;
The content of barium sulfate in the negative electrode material is 0.2% by mass or more and 0.7% by mass or less,
The present invention relates to a lead-acid battery, wherein the density of the negative electrode material is 3.8 g / cm ³ or more.

  According to the above aspect of the present invention, a negative electrode plate can be easily manufactured, and a high cycle life performance of a lead storage battery can be obtained even when deep discharge is performed.

It is a perspective view showing typically the state where the lid of the lead storage battery concerning one side of the present invention was removed. It is a front view of the lead storage battery of FIG. FIG. 2B is a cross-sectional view of the lead storage battery of FIG. 2A taken along line IIB-IIB. It is a graph which shows the relationship between cycle life performance evaluated about lead storage batteries A1-A8 and B1-B8 and density of a negative electrode material. It is a graph which shows the relationship between the cycle life performance evaluated about lead storage batteries A3, A11-A16, B3, and B11-B16, and the content of barium sulfate in a negative electrode material.

A lead storage battery according to one aspect of the present invention includes a negative electrode plate and a positive electrode plate. The negative electrode plate includes a negative electrode material containing a carbon material and barium sulfate. The carbon material includes a first carbon material having a particle diameter of 32 μm or more and a second carbon material having a particle diameter of less than 32 μm. The ratio of the powder resistance R2 of the second carbon material to the powder resistance R1 of the first carbon material: R2 / R1 is more than 15 and less than 230. The content of barium sulfate in the negative electrode material is 0.2% by mass or more and 0.7% by mass or less, and the density of the negative electrode material is 3.8 g / cm ³ or more.

Generally, in a negative electrode plate of a lead-acid battery, when the density of the negative electrode material is increased, the conductivity of the negative electrode material is increased, and the distance between the negative electrode active materials included in the negative electrode material is reduced, so that Pb ²⁺ It is known that the diffusion rate of ions increases and the charging reaction rate improves. Therefore, it is considered that when the density of the negative electrode material is high, accumulation of lead sulfate in the negative electrode plate is suppressed, and the cycle life performance is improved.

On the other hand, conventionally, carbon black has been added to the negative electrode material from the viewpoint of increasing conductivity. The negative electrode plate is manufactured using a paste containing a negative electrode material, and a large amount of carbon black adsorbs a solvent contained in the paste. Therefore, in the conventional paste containing carbon black, the fluidity and extensibility of the paste are significantly reduced, and the applicability of the paste to the current collector is extremely low. In general, from the viewpoint of uniformly applying the negative electrode material to the current collector, application using a machine such as a filling machine (paster) dedicated to application of the paste is employed. However, when the density of the negative electrode material is increased, since the solid content of the paste increases, the applicability of the paste in particular decreases. For example, when carbon black alone is added to the negative electrode material so that the content of the carbon black in the negative electrode material becomes 0.6% by mass, the upper limit density at which mechanical application can be performed is approximately 3.6 g / cm. ³ . Therefore, when carbon black is used alone, when the density of the negative electrode material is higher than 3.6 g / cm ³ , mechanical coating is more difficult than before. When it is difficult to apply the paste mechanically, it is difficult to industrially manufacture the negative electrode plate.

The present inventor has found that when the density of the negative electrode material is 3.6 g / cm ³ or less, the first carbon material or the second carbon material may be used alone, or both carbon materials may be used in combination. And noticed that the cycle life performance did not change much. In general, the higher the density of the negative electrode material, the higher the cycle life performance and charge acceptance performance, and the lowering of the capacity is suppressed even during a charge / discharge cycle including deep discharge. However, the examination results of the present inventors have revealed that when the first carbon material is used alone, even if the density of the negative electrode material is increased, the additional effect of increasing the cycle life is not so much seen.

  Note that carbon materials having various powder resistances are generally known. It is known that the powder resistance of a powder material changes depending on the shape, diameter, internal structure of particles, and / or crystallinity of particles. In the prior art common sense, the powder resistance of the carbon material has no direct relation to the resistance of the negative electrode plate of the lead-acid battery, and is not considered to affect the cycle life performance.

  In addition, barium sulfate has been conventionally considered to be added to a negative electrode material of a lead-acid battery for the purpose of suppressing osmotic short circuit and suppressing aggregation of lead sulfate accumulated in a negative electrode plate. However, since barium sulfate is a non-conductor, depending on the composition of the negative electrode material, it may not be possible to charge even if the density of the negative electrode material is increased when a charge / discharge cycle including deep discharge is performed. Also in this case, the cycle life performance decreases.

According to the above aspect of the present invention, when the density of the negative electrode material is as high as 3.8 g / cm ³ or more, the first carbon having a different particle diameter and a powder resistance ratio R2 / R1 of more than 15 and less than 230 is used. The material and the second carbon material are combined. As a result, the extensibility of the paste containing the negative electrode material (hereinafter, also referred to as the negative electrode paste) is increased, and the applicability is improved. Therefore, despite the high density of the negative electrode material, The negative electrode paste can be mechanically applied, and the production of the negative electrode plate is easy. As described above, according to the above aspect of the present invention, a negative electrode plate can be easily manufactured despite the high density of the negative electrode material. The reason why the coatability of the negative electrode paste is improved when the powder resistance ratio R2 / R1 is within the above range is that when the powder resistance ratio R2 / R1 is within the above range, the surface state of each carbon material is optimized, It is considered that the adsorption of the solvent is appropriately suppressed.

  In addition, in this specification, excellent applicability of the negative electrode paste means that the negative electrode paste can be applied to the negative electrode current collector by a machine (specifically, a paster).

  According to the above aspect of the present invention, by combining the first carbon material and the second carbon material, the first carbon material and the second carbon material are more uniformly filled in the layer of the high-density negative electrode material. can do. Therefore, many conductive networks are easily formed in the negative electrode material. Increasing the density of the negative electrode material forms a charging reaction field with a dense conductive network containing metal lead particles, increases the charging reaction speed in the negative electrode material, and improves cycle life performance.

  Further, by setting the content of barium sulfate in the negative electrode material to be 0.2% by mass or more and 0.7% by mass or less, charge / discharge can be repeated even when performing a charge / discharge cycle involving deep discharge. it can. Therefore, even when deep discharge is involved, it is possible to suppress a decrease in the cycle life performance of the lead storage battery. From the viewpoint of further improving the effect of improving the cycle life performance, the content of barium sulfate in the negative electrode material is preferably 0.2% by mass or more and 0.6% by mass or less.

The density of the negative electrode material is preferably 4.1 g / cm ³ or more. Even when the density of such a negative electrode material is high, a uniform layer of the negative electrode material is easily formed because the coating property of the negative electrode plate is high. Further, since many conductive networks are formed, the cycle life performance can be further improved.

  Generally, when the density of the negative electrode material is increased, the amount of diluted sulfuric acid used in preparing the paste is reduced, and / or the concentration of sulfuric acid in the diluted sulfuric acid is reduced in order to maintain the applicability of the paste. That is being done. As a result, the amount of sulfate in the negative electrode material is reduced. When the amount of sulfate is reduced, generally, the progress of the paste is increased, while the amount of lead sulfate in the negative electrode material is reduced in the obtained negative electrode plate. It is known that when such a negative electrode plate (unformed negative electrode plate) is stored in the air, there arises a problem that the content of lead carbonate in the negative electrode material increases. It has been found that when the content of lead carbonate in the negative electrode material increases, the negative electrode material may fall off and / or the initial capacity of the negative electrode plate may decrease. For example, when an unformed negative electrode plate containing approximately 20% by mass or more of lead carbonate in the negative electrode material is formed, the negative electrode material may fall off and / or the initial capacity of the negative electrode plate may decrease. That is, the storage performance of the unformed negative electrode plate is reduced. From the viewpoint of suppressing the deterioration of the preservation performance of the unformed negative electrode plate, the conventional methods include, for example, contacting the negative electrode plate after applying the paste with dilute sulfuric acid to impregnate sulfate groups on the surface of the negative electrode plate. There is a way to make it happen. However, even if such a method is employed, it is not possible to supply a sufficient amount of sulfate for maintaining the storage performance.

Also in the above aspect of the present invention, if the density of the negative electrode material is too high, it may be difficult to obtain high storage performance. Therefore, from the viewpoint of ensuring high storage performance of the unformed negative electrode plate, the density of the negative electrode material is preferably set to less than 4.7 g / cm ³ .

In preparing the negative electrode paste, it is preferable to add a carbon material that does not reduce the extensibility and storage performance of the negative electrode paste so as not to reduce the amount of sulfate groups. As such a carbon material, a first carbon material and a second carbon material having a ratio S2 / S1 of the specific surface area S2 of the second carbon material to the specific surface area S1 of the first carbon material of 350 or less are used. Is preferred. The effect of the first carbon material and the second carbon material exhibiting such an S2 / S1 ratio is particularly remarkable when the density of the negative electrode material is less than 4.7 g / cm ³ . When the specific surface area ratio S2 / S1 is 350 or less, the applicability of the negative electrode paste is improved.

Hereinafter, the lead storage battery according to the embodiment of the present invention will be described for each of the main components, but the present invention is not limited to the following embodiment.
(Negative electrode plate)
The negative electrode plate of the lead storage battery includes a negative electrode material. The negative electrode plate can usually be composed of a negative electrode current collector (eg, a negative electrode grid) and a negative electrode material. The negative electrode material is obtained by removing the negative electrode current collector from the negative electrode plate.
Note that a member such as a mat or pasting paper may be attached to the negative electrode plate. When the negative electrode plate includes such a member (sticking member), the negative electrode material excludes the negative electrode current collector and the sticking member. However, the thickness of the electrode plate is a thickness including the mat. When a mat is attached to the separator, the thickness of the mat is included in the thickness of the separator.

  The negative electrode material includes a negative electrode active material (lead or lead sulfate) that develops a capacity by an oxidation-reduction reaction. The negative electrode active material in a charged state is spongy metal lead, but an unformed negative electrode plate is usually produced using lead powder. The negative electrode material contains a carbon material and barium sulfate. The negative electrode material may further contain an organic shrinking agent or the like, and may further contain other additives as necessary.

(Carbon material)
The carbon material includes a first carbon material having a particle diameter of 32 μm or more and a second carbon material having a particle diameter of less than 32 μm. The first carbon material and the second carbon material are separated and distinguished in a procedure described later.

  Examples of each carbon material include carbon black, graphite, hard carbon, soft carbon, and the like. Examples of the carbon black include acetylene black, furnace black, lamp black and the like. The graphite may be any carbon material having a graphite-type crystal structure, and may be artificial graphite or natural graphite.

The intensity of a peak appearing in 1300 cm ^-1 or 1350 cm ^-1 or less in the range of the Raman spectrum (D band) and 1550 cm ^-1 or 1600 cm ^-1 peak appearing in the range (G band) of the first carbon material A carbon material having a ratio I _D / I _G of 0 or more and 0.9 or less is referred to as graphite.

  The first carbon material and the second carbon material are each a negative electrode so that the ratio of the powder resistance R2 of the second carbon material to the powder resistance R1 of the first carbon material: R2 / R1 is more than 15 and less than 230. The type, specific surface area, and / or aspect ratio of the carbon material used for preparing the material may be selected or adjusted. Further, in addition to these factors, the particle size of the carbon material to be used may be further adjusted. By selecting or adjusting these factors, the powder resistance of each of the first carbon material and the second carbon material can be adjusted, and as a result, the powder resistance ratio R2 / R1 can be adjusted. it can.

  As the first carbon material, for example, at least one selected from the group consisting of graphite, hard carbon, and soft carbon is preferable. In particular, the first carbon material preferably contains at least graphite. The second carbon material preferably contains at least carbon black. When these carbon materials are used, the powder resistance ratio R2 / R1 is easily adjusted.

  The ratio (powder resistance ratio R2 / R1) of the powder resistance R2 of the second carbon material to the powder resistance R1 of the first carbon material may be more than 15 and less than 230. When the powder resistance ratio is in such a range, high applicability of the negative electrode paste can be obtained, and cycle life performance can be improved. From the viewpoint of obtaining higher cycle life performance, the powder resistance ratio R2 / R1 is preferably 80 or more. From the same viewpoint, the powder resistance ratio R2 / R1 is preferably 220 or less. From the viewpoint of ensuring high storage performance of the unformed negative electrode plate, the powder resistance ratio R2 / R1 is preferably less than 160, and more preferably 150 or less. These lower and upper limits can be arbitrarily combined. The powder resistance ratio R2 / R1 is, for example, more than 15 and 220 or less (or less than 160 or 150 or less), and 80 or more and less than 230 (or 220 or less, less than 160 or 150 or less).

The ratio of the specific surface area S2 of the second carbon material to the specific surface area S1 of the first carbon material: S2 / S1 is preferably 350 or less. When the specific surface area ratio S2 / S1 is within such a range, even when the density of the negative electrode material is increased, the applicability of the negative electrode paste can be further improved. When the first carbon material and the second carbon material having the S2 / S1 ratio of 350 or less are used, high storage performance of the unformed negative electrode plate can be secured. The effect of the storage performance due to the S2 / S1 ratio is particularly high when the density of the negative electrode material is less than 4.7 g / cm ³ (preferably 4.6 g / cm ³ or less, more preferably 4.5 g / cm ³ or less). ).

  The average aspect ratio of the first carbon material is, for example, 1 or more and 200 or less, and may be 1.5 or more and 100 or less, or 1.5 or more and 35 or less.

  The total content of the first carbon material and the second carbon material in the negative electrode material is, for example, 0.1% by mass or more, preferably 0.2% by mass or more, and an effect of improving cycle life performance. Is more preferably 0.3% by mass or more from the viewpoint of further increasing. The upper limit of the total content of the first carbon material and the second carbon material depends on the density of the negative electrode material, the type of each carbon material, and the like, but can be, for example, 1.5% by mass or less.

  Among the carbon materials, the content of the first carbon material in the negative electrode material is, for example, 0.05% by mass or more, from the viewpoint of high applicability of the negative electrode paste and a high effect of improving the cycle life, It is preferably at least 0.1% by mass or at least 0.2% by mass. The upper limit of the content of the first carbon material in the negative electrode material depends on the density of the negative electrode material, the type of the carbon material, and the like, but is, for example, 1.5% by mass or less. What is necessary is just to adjust so that the sum of content with a carbon material may be in the said range.

  The content of the second carbon material in the negative electrode material is, for example, 0.03% by mass or more, and from the viewpoint of easily forming a conductive network in the negative electrode material, is preferably 0.1% by mass or more. .2% by mass or more. The upper limit of the content of the second carbon material in the negative electrode material depends on the density of the negative electrode material, the type of the carbon material, and the like, but is, for example, 1% by mass or less and 0.6% by mass or less. Is more preferable, and it is more preferable that it is 0.4 mass% or less. The content of the second carbon material may be adjusted so that the sum of the content of the first carbon material and the content of the second carbon material is in the above range. The content of the second carbon material is, for example, 0.03 mass% or more and 1 mass% or less (or 0.6 mass% or less or 0.4 mass% or less), 0.1 mass% or more and 1 mass% or less ( Alternatively, it may be 0.6% by mass or less or 0.4% by mass or less, or 0.2% by mass or more and 1% by mass or less (or 0.6% by mass or less or 0.4% by mass or less). .

The method for determining or analyzing the physical properties of the carbon material will be described below.
(A) Analysis of carbon material (A-1) Separation of carbon material The already-charged fully charged lead-acid battery is disassembled, the negative electrode plate is taken out, sulfuric acid is removed by washing with water, and vacuum drying (under a pressure lower than atmospheric pressure) Dry). Next, the negative electrode material is collected from the dried negative electrode plate and crushed. To 5 g of the crushed sample, 30 mL of a 60% by mass aqueous solution of nitric acid is added and heated at 70 ° C. To this mixture, 10 g of disodium ethylenediaminetetraacetate, 30 mL of 28% by mass aqueous ammonia and 100 mL of water are further added, and heating is continued to dissolve soluble matter. The sample thus pretreated is collected by filtration. The collected sample is passed through a sieve having an opening of 500 μm to remove components having a large size such as a reinforcing material, and the components passing through the sieve are collected as a carbon material.

  Then, when the recovered carbon material is sieved in a wet manner using a sieve having an opening of 32 μm, the material remaining on the sieve without passing through the sieve is used as the first carbon material, and the sieve is sifted. The passing material is assumed to be the second carbon material. That is, the particle size of each carbon material is based on the size of the sieve opening. Regarding wet sieving, JIS Z8815: 1994 can be referred to. Specifically, the carbon material is placed on a sieve having a mesh size of 32 μm, and the sieve is gently shaken for 5 minutes while sprinkling with ion-exchanged water. The first carbon material remaining on the sieve is recovered from the sieve by flowing ion-exchanged water, and separated from the ion-exchanged water by filtration. The second carbon material that has passed through the sieve is collected by filtration using a nitrocellulose membrane filter (opening: 0.1 μm). The recovered first and second carbon materials are each dried at a temperature of 110 ° C. for 2 hours. As the sieve having a mesh size of 32 μm, a sieve provided with a mesh having a nominal mesh size of 32 μm, which is defined in JIS Z8801-1: 2006, is used.

  The content of each carbon material in the negative electrode material is determined by measuring the mass of each carbon material separated in the above procedure, and calculating the ratio (% by mass) of this mass to the 5 g of the crushed sample. Shall be sought.

In the present specification, the fully charged state of the lead storage battery means that in the case of a liquid battery, after performing constant current charging at a current of 0.2 CA in a 25 ° C. water tank until reaching 2.5 V / cell, This is a state in which constant current charging is performed at 0.2 CA for 2 hours. Further, in the case of a control valve type battery, the fully charged state is a constant current constant voltage charge of 2.23 V / cell at 0.2 CA in a 25 ° C. air tank, and a charge current at the time of constant voltage charge. Is a state in which the charging has been completed at the time point when the value becomes 1 mCA or less.
In this specification, 1 CA is a current value (A) having the same numerical value as the nominal capacity (Ah) of the battery. For example, if the battery has a nominal capacity of 30 Ah, 1 CA is 30 A and 1 mCA is 30 mA.

(A-2) Powder resistance of the carbon material The powder resistance R1 of the first carbon material and the powder resistance R2 of the second carbon material are calculated based on the first carbon material and the second carbon material separated by the procedure (A-1). For each of the two carbon materials, 0.5 g of a sample was charged into a powder resistance measuring system (MCP-PD51 type, manufactured by Mitsubishi Chemical Analytech Co., Ltd.), and under a pressure of 3.18 MPa, according to JIS K 7194: 1994. It is a value measured by a four-probe method using a low resistance resistivity meter (Loresta-GX MCP-T700, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) based on the above method.

(A-3) Specific surface area of carbon material The specific surface area S1 of the first carbon material and the specific surface area S2 of the second carbon material are the BET specific surface areas of the first carbon material and the second carbon material, respectively. The BET specific surface area is determined using the BET equation by a gas adsorption method using each of the first carbon material and the second carbon material separated in the procedure (A-1). Each carbon material is pretreated by heating at a temperature of 150 ° C. for 1 hour in a nitrogen flow. Using the pretreated carbon material, the BET specific surface area of each carbon material is determined by the following apparatus under the following conditions.
Measurement device: TriStar 3000 manufactured by Micromeritics
Adsorption gas: Nitrogen gas with a purity of 99.99% or more Adsorption temperature: Liquid nitrogen boiling point temperature (77K)
Calculation method of BET specific surface area: Based on 7.2 of JIS Z 8830: 2013

(A-4) Average aspect ratio of first carbon material The first carbon material separated by the procedure of the above (A-1) is observed with an optical microscope or an electron microscope, and 10 or more arbitrary particles are selected. , Take the enlarged photo. Next, a photograph of each particle is subjected to image processing to obtain a maximum diameter d1 of the particle and a maximum diameter d2 in a direction orthogonal to the maximum diameter d1, and by dividing d1 by d2, the aspect ratio of each particle is obtained. Ask. The average aspect ratio is calculated by averaging the obtained aspect ratios.

(Barium sulfate)
The content of barium sulfate contained in the negative electrode material may be 0.2% by mass or more and 0.7% by mass or less. When the content of barium sulfate is in such a range, since the electron conductivity between the metal lead particles is not hindered, even when deep discharge is performed, lead sulfate is easily reduced at the time of charging. Accordingly, it is possible to prevent the charge from being difficult to progress during the charge / discharge cycle involving the deep discharge. Therefore, even in a charge / discharge cycle involving deep discharge, charge / discharge can be repeatedly performed, and a decrease in cycle life performance is suppressed. From the viewpoint of further improving the effect of improving the cycle life performance, the content is preferably 0.2% by mass or more and 0.6% by mass or less.

A method for determining the content of barium sulfate contained in the negative electrode material will be described below.
(B) Analysis of barium sulfate (B-1) A sample of about 5 g is taken out of the pulverized sample taken out of the lead storage battery in the same manner as in (A-1) above, and the mass m1 (g) is accurately weighed. The weighed sample is put into 30 cm ³ of a 10% by mass aqueous nitric acid solution and dissolved by heating. After cooling the resulting mixture, deionized water is added until the volume reaches 100 cm ^{3 and} left for 30 minutes, and the supernatant is collected in another beaker. To the remaining precipitate, 20 g of ammonium acetate and 30 cm ^{3 of} water are added and dissolved by heating. The obtained solution is poured into the above supernatant, boiled, heated in this state for 5 minutes, and then left for 1 hour. The obtained mixture is filtered with a membrane filter of known mass, and the filtrate is collected. The components remaining on the membrane filter are sufficiently washed with water. The used membrane filter is dried at 110 ° C. for 2 hours, and the weight after drying is measured. From the measured value, the insoluble residue mass m2 is determined by subtracting the initial mass of the membrane filter. The dried membrane filter is placed in a porcelain crucible of known mass, and is burned and ashed. Next, the crucible is cooled to room temperature in a desiccator, the mass is measured, and the mass m3 of the residual burning is determined by subtracting the initial mass of the crucible from this mass.

(B-2) Take the filtrate collected in (B-1) above into a volumetric flask and add deionized water until the volume becomes 250 cm ³ . The atomic absorbance of the obtained solution is measured by an atomic absorption method using an Air-C ₂ H ₂ flame by selecting a spectral line of 553.6 nm. The atomic absorbance is measured using an atomic absorption spectrophotometer (AA7000F, manufactured by Shimadzu Corporation). The concentration of barium element in the solution was determined from the above-mentioned atomic absorbance based on a calibration curve separately prepared using a standard-concentration Ba salt solution, and the mass m4 (mg) of the barium element contained in the filtrate was determined. Ask. Then, the content c1 (% by mass) of the soluble barium sulfate contained in the negative electrode material is calculated by the following equation.
c1 = 100 × (M1 / M2) × (m4 / m1)
Here, M1 is the molecular weight of barium sulfate (BaSO ₄ ), and M2 is the atomic weight of barium (Ba). A value of M1 / M2 = 1.699 is used.

(B-3) The insoluble barium sulfate content c2 (% by mass) contained in the negative electrode material is calculated from the following formula from the mass m3 of the burning residue of (B-1).
c2 = 100 × m3 / m1
Then, by adding c1 and c2, the content (% by mass) of barium sulfate contained in the negative electrode material in a fully-charged state after being formed is obtained.

(Organic shrinkproofing agent)
The organic shrinking agent contained in the negative electrode material is an organic polymer containing a sulfur element, and generally contains one or more, preferably a plurality of aromatic rings in the molecule, and contains a sulfur element as a sulfur-containing group. I have. Among the sulfur-containing groups, a stable form of a sulfonic acid group or a sulfonyl group 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 the organic shrinking agent, for example, lignins may be used, or a synthetic organic shrinking agent may be used. As the synthetic organic shrinking agent, a condensate of an aromatic compound having a sulfur-containing group with formaldehyde may be used. Examples of the lignins include lignin, lignin derivatives such as lignin sulfonic acid or a salt thereof (eg, an alkali metal salt such as a sodium salt). As the organic shrinking agent, one kind may be used alone, or two or more kinds may be used in combination. For example, lignins and a condensate of an aromatic compound having a sulfur-containing group with formaldehyde may be used in combination. As the aromatic compound, it is preferable to use bisphenols, biphenyls, naphthalenes and the like.

  The content of the organic shrinking agent contained in the negative electrode material is, for example, from 0.01% by mass to 1.0% by mass, and preferably from 0.02% by mass to 0.8% by mass.

  Hereinafter, a method for quantifying the organic shrinking agent contained in the negative electrode material will be described. Prior to the quantitative analysis, the charged lead storage battery is fully charged and then disassembled to obtain a negative electrode plate to be analyzed. The obtained negative electrode plate is washed with water 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 uncrushed initial sample.

[Organic shrinkproofing agent]
The pulverized initial sample is pulverized, and the pulverized initial sample is immersed in a 1 mol / L NaOH aqueous solution to extract an organic shrinking agent. Insoluble components are removed by filtration from the aqueous NaOH solution containing the extracted organic shrinking agent. The obtained filtrate (hereinafter, also referred to as a filtrate to be analyzed) is desalted, concentrated and dried to obtain a powder of an organic shrinking agent (hereinafter, also referred to as a powder to be analyzed). Desalting may be performed by placing the filtrate in a dialysis tube and immersing it in distilled water.

  The infrared spectrum of the powder to be analyzed, the ultraviolet-visible absorption spectrum of the solution obtained by dissolving the powder of analysis in distilled water, the NMR spectrum of the solution obtained by dissolving the powder of analysis in a solvent such as heavy water, The organic shrinking agent is specified by obtaining information from pyrolysis GC-MS or the like, which can obtain information on each of the constituent compounds.

  An ultraviolet-visible absorption spectrum of the filtrate to be analyzed is measured. Using the spectral intensity and a calibration curve prepared in advance, the content of the organic shrinking agent in the negative electrode material is quantified. When the structural formula of the organic preservative to be analyzed cannot be strictly specified and a calibration curve of the same organic preservative cannot be used, an ultraviolet-visible absorption spectrum, an infrared spectroscopy spectrum similar to that of the organic preservative to be analyzed, A calibration curve is prepared using an available organic shrinking agent that shows NMR spectra and the like.

(Density of negative electrode material)
The density of the negative electrode material may be any 3.8 g / cm ³ or more, preferably 4.1 g / cm ³ or more. Even in the case of such a high density, the present invention can provide high coating properties and excellent cycle life performance. In addition, high storage performance of an unformed negative electrode plate can be obtained. The density of the negative electrode material is, for example, 4.7 g / cm ³ or less. From tends viewpoint ensure high storage performance of the negative plate which was not chemically converted, preferably less than ^{4.7g / cm 3, 4.6g / cm} 3 or less, or 4.5 g / cm ³ or less is still more preferable. These lower and upper limits can be arbitrarily combined. The density of the negative electrode material, for example, 3.8 g / cm ³ or more 4.7 g / cm ³ or less (or less than ^{4.7g / cm 3, 4.6g / cm} 3 or less, or 4.5 g / cm ³ or less ) 4.1 g / cm ³ or more and 4.7 g / cm ³ or less (or less than 4.7 g / cm ³ , 4.6 g / cm ³ or less or 4.5 g / cm ³ or less).

  The density of the negative electrode material means the value of the bulk density of the negative electrode material in a fully charged state after formation, and is measured as follows. The battery after chemical formation is fully charged and then disassembled, and the obtained negative electrode plate is washed with water and dried to remove the electrolytic solution in the negative electrode plate. Next, the negative electrode material is separated from the negative electrode plate to obtain an uncrushed measurement sample. After charging the sample into the measurement container and evacuating, the mercury is filled at a pressure of 0.5 psia or more and 0.55 psia or less (≒ 3.45 kPa or more and 3.79 kPa or less), and the bulk volume of the negative electrode material is measured. The bulk density of the negative electrode material is determined by dividing the mass of the measurement sample by the bulk volume. The volume obtained by subtracting the mercury injection volume from the volume of the measurement container is defined as the bulk volume. The density of the negative electrode material is measured using an automatic porosimeter (Autopore IV9505) manufactured by Shimadzu Corporation.

(Other)
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 an expanding process and a punching (punching) process.

  The lead alloy used for the negative electrode current collector may be any of a Pb-Sb-based alloy, a Pb-Ca-based alloy, and a Pb-Ca-Sn-based alloy. These lead alloys may further include at least one selected from the group consisting of Ba, Ag, Al, Bi, As, Se, Cu, and the like as an additional element. Among these, a Pb-Sb-based alloy is preferable, and this alloy may further include at least one selected from the group consisting of Ag, Al, As, Se, and the like as an additional element.

  The negative electrode plate can be formed by filling a negative electrode current collector with a negative electrode paste, aging and drying to prepare an unformed negative electrode plate, and then forming the unformed negative electrode plate. The negative electrode paste is prepared by adding water and diluted sulfuric acid to a lead powder, a carbon material, and, if necessary, an organic shrinking agent and / or various additives, and kneading the mixture. In aging, it is preferable to ripen the unformed negative electrode plate at a temperature higher than room temperature and high humidity.

  The formation of the negative electrode plate can be performed by charging the electrode group while the electrode 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. . The formation may be performed before assembling the lead storage battery or the electrode plate group. Chemical formation produces spongy metallic lead.

(Positive electrode plate)
There are a paste type and a clad type for the positive electrode plate of the lead storage battery.
The paste-type positive electrode plate includes a positive electrode current collector and a positive electrode material. The positive electrode material is held on 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 rolled sheet of lead or a lead alloy slab.

  The clad-type positive electrode plate includes a plurality of porous tubes, a core bar inserted into each tube, a current collector connecting the core bars, and a positive electrode material filled in the tube into which the core bars are inserted. And a connecting part for connecting the plurality of tubes. The core and the current collector that connects the core are collectively referred to as a positive electrode current collector.

  Examples of the lead alloy used for the positive electrode current collector include a Pb-Ca-based alloy, a Pb-Sb-based alloy, and a Pb-Ca-Sn-based alloy. Among them, it is preferable to use a Pb-Sb alloy.

  The positive electrode material contains a positive electrode active material (lead dioxide or lead sulfate) that develops a capacity by an oxidation-reduction reaction. The positive electrode material may contain other additives as needed.

  An unformed paste-type positive electrode plate is obtained by filling a positive electrode current collector with a positive electrode paste, aging, and drying, as in the case of the negative electrode plate. The positive electrode paste is prepared by kneading lead powder, additives, water, and sulfuric acid.

  The clad-type positive electrode plate is formed by filling lead powder or slurry-like lead powder into a tube into which a metal core has been inserted, and connecting a plurality of tubes in a continuous manner.

  The formed unformed positive electrode plate is further formed. Chemical conversion produces lead dioxide. The formation of the positive electrode plate may be performed before assembling the lead storage battery or the electrode plate group.

(Separator)
Usually, a separator is arranged between the negative electrode plate and the positive electrode plate. A nonwoven fabric, a microporous film, or the like is used for the separator. The thickness and the number of separators interposed between the negative electrode plate and the positive electrode plate may be selected according to the distance between the electrodes.
A nonwoven fabric is a mat that is entangled without weaving fibers, and is mainly made of fibers. For example, 60% by mass or more of the separator is formed of fibers. As the fibers, glass fibers, polymer fibers (polyolefin fibers, acrylic fibers, polyester fibers such as polyethylene terephthalate fibers, and the like), pulp fibers, and the like can be used. Among them, glass fibers are preferred. The nonwoven fabric may contain components other than fibers, for example, an acid-resistant inorganic powder, a polymer as a binder, and the like.

  On the other hand, the microporous membrane is a porous sheet mainly composed of components other than the fiber component. For example, a composition containing a pore-forming agent (such as polymer powder and / or oil) is extruded into a sheet and then formed into a sheet. It is obtained by removing the agent to form pores. The microporous membrane is preferably made of a material having acid resistance, and is preferably a polymer mainly composed of a polymer component. As the polymer component, a polyolefin such as polyethylene and polypropylene is preferable.

  The separator may be composed of, for example, only a nonwoven fabric, or may be composed of only a microporous membrane. The separator may be a laminate of a nonwoven fabric and a microporous membrane, a material obtained by bonding different or similar materials, or a material obtained by engaging different or similar materials with irregularities, if necessary.

(Electrolyte)
Electrolyte is an aqueous solution containing sulfuric acid, specific gravity at 20 ° C. of the electrolytic solution in lead-acid battery in a fully charged state after the conversion is, for example, 1.10 g / cm ³ or more 1.35 g / cm ³ or less, 1 it is preferable .10g / cm ³ or more 1.30 g / cm ³ or less, or 1.20 g / cm ³ or more 1.30 g / cm ³ or less.

FIG. 1 is a perspective view schematically showing an example of a lead storage battery according to an embodiment of the present invention with a lid 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 accommodates an electrode group 11 and an electrolyte 12. A battery case 10 is provided. The electrode plate group 11 is configured by laminating a plurality of negative electrode plates 2 and positive electrode plates 3 via a separator 4. Here, a state in which the negative electrode plate 2 is wrapped with the bag-shaped separator 4 is shown, but the form of the separator is not particularly limited.

  At the upper part of each of the plurality of negative electrode plates 2, a current collecting ear (not shown) projecting upward is provided. Ears (not shown) for current collection protruding upward are also provided on each of the plurality of positive electrode plates 3. The ears of the negative electrode plate 2 are connected and integrated by a negative electrode strap 5a. Similarly, the ear portions of the positive electrode plate 3 are also connected by a positive electrode strap 5b and integrated. The lower end of the negative pole 6a is fixed to the upper part of the negative strap 5a, and the lower end of the positive pole 6b is fixed to the upper part of the positive strap 5b.

A lead storage battery according to one aspect of the present invention will be described below.
(1) One aspect of the present invention is a lead storage battery,
The lead storage battery includes a negative electrode plate and a positive electrode plate,
The negative electrode plate includes a negative electrode material containing a carbon material and barium sulfate,
The carbon material includes a first carbon material having a particle diameter of 32 μm or more, and a second carbon material having a particle diameter of less than 32 μm,
The ratio of the powder resistance R2 of the second carbon material to the powder resistance R1 of the first carbon material: R2 / R1 is more than 15 and less than 230;
The content of barium sulfate in the negative electrode material is 0.2% by mass or more and 0.7% by mass or less,
A lead-acid battery, wherein the density of the negative electrode material is 3.8 g / cm ³ or more.

  (2) In the above (1), the ratio: R2 / R1 is preferably 80 or more and less than 230.

  (3) In the above (1) or (2), the ratio: R2 / R1 is preferably 80 or more and 220 or less.

(4) In any one of the above (1) to (3), the density of the negative electrode material is preferably 4.1 g / cm ³ or more.

(5) In any one of the above (1) to (4), the density of the negative electrode material is preferably less than 4.7 g / cm ³ .

  (6) In (5) above, it is preferable that the ratio of the specific surface area S2 of the second carbon material to the specific surface area S1 of the first carbon material: S2 / S1 is 350 or less.

  (7) In any one of the above (1) to (6), the content of barium sulfate in the negative electrode material is preferably 0.2% by mass or more and 0.6% by mass or less.

  (8) In any one of the above (1) to (7), the ratio: R2 / R1 is preferably 80 or more and less than 160.

  (9) In any one of the above (1) to (8), the ratio: R2 / R1 is preferably 80 or more and 150 or less.

(10) In the above (6), the density of the negative electrode material is preferably 4.6 g / cm ³ or less or 4.5 g / cm ³ or less.

  (11) In any one of the above (1) to (10), the content of the first carbon material in the negative electrode material is preferably 0.05% by mass or more.

  (12) In any one of the above (1) to (11), the content of the first carbon material in the negative electrode material is, for example, 1.5% by mass or less.

  (13) In any one of the above (1) to (12), the content of the second carbon material in the negative electrode material is preferably 0.1% by mass or more.

  (14) In any one of the above (1) to (13), the content of the second carbon material in the negative electrode material is preferably 0.6% by mass or less.

  (15) In any one of the above (1) to (14), preferably, the first carbon material contains at least graphite, and the second carbon material contains at least carbon black.

[Example]
Hereinafter, the present invention will be specifically described based on examples and comparative examples, but the present invention is not limited to the following examples.

<< Lead storage battery A1 >>
In the following procedure, a lead-acid battery A1 for a forklift having a nominal capacity of 200 Ah and having three clad electrodes and four paste electrodes on a positive electrode plate and a negative electrode plate is prepared.

(1) Preparation of Negative Electrode Plate The negative electrode plate is prepared by applying a negative electrode paste to a plate-like grid-shaped negative electrode current collector (long side length 271 mm, short side length 142 mm, thickness 2.8 mm or more and 3.7 mm or less). Produced. At this time, the mass of the negative electrode material after formation was 465 ± 6 g per negative electrode plate, and the density of the negative electrode material was the design value in Table 1, so that the negative electrode current collector and the paste coating layer were formed. Adjust the thickness. The application of the negative electrode paste is performed using a paster (manufactured by Winkel) so that the grid of the current collector has no gap. However, when the paste of the negative electrode paste cannot be applied with a paster, the paste is applied manually using a trowel.

The negative electrode paste is prepared by mixing lead powder, water, dilute sulfuric acid, barium sulfate, a carbon material, and an organic shrinking agent using a mixer (manufactured by Dalton).
As the carbon material, carbon black (Ketjen Black (registered trademark)) and graphite (flaky graphite, average particle diameter D ₅₀ : 110 μm) are used. Sodium lignin sulfonate is used as the organic shrinkproofing agent, and the amount added is adjusted so that the content contained in 100% by mass of the negative electrode material is 0.1% by mass, and is blended into the negative electrode paste. The content (design value) of barium sulfate contained in 100% by mass of the negative electrode material is 0.6% by mass. When preparing the negative electrode paste, the amounts of water and dilute sulfuric acid added to the negative electrode paste are adjusted so that the density of the negative electrode material after being fully formed and fully charged has the design value shown in Table 1. The density (measured value) of the negative electrode material obtained from the measurement sample obtained by disassembling the already-formed and fully charged battery by the above-described procedure and collected from the measurement sample has almost no difference.

(2) Production of Positive Electrode Plate As the positive electrode plate, a clad electrode plate in which 14 tubes each having an outer diameter of 10 mm are filled with a positive electrode material is used. The coating amount of the positive electrode material is adjusted so that the mass of the positive electrode material after formation becomes 792 ± 8 g per positive electrode plate.

(3) Assembly of lead storage battery The obtained negative electrode plate and positive electrode plate are immersed in dilute sulfuric acid having a concentration of 7% by mass, and a tank is formed in this state. The negative electrode plate and the positive electrode plate after the formation are laminated with a separator interposed therebetween to produce an electrode plate group. The obtained electrode group is put in a battery case, and 2,000 cm ^{3 of} dilute sulfuric acid having a specific gravity of 1.28 at 20 ° C. is injected to produce a lead storage battery A1. Similarly, a total of four lead storage batteries A1 are manufactured.

  In the present lead-acid battery, the content of the first carbon material contained in the negative electrode material is set to 0.4% by mass, and the content of the second carbon material is set to 0.2% by mass. The powder resistance ratio R2 / R1 is set to 100. The ratio (= S2 / S1) of the specific surface area S2 of the second carbon material to the specific surface area S1 of the first carbon material is 350. However, these values are obtained when the negative electrode plate of the manufactured lead storage battery is taken out and the carbon material contained in the negative electrode material is separated into the first carbon material and the second carbon material by the above-described procedure. This is a value determined as the content of each carbon material contained in the electrode material (100% by mass). The powder resistances R1 and R2, the powder resistance ratio R2 / R1, and the specific surface area ratio S2 / S1 of each carbon material are also determined from the lead storage battery manufactured according to the procedure described above.

<< Lead storage batteries A2 to A8 >>
The amounts of water and dilute sulfuric acid added to the negative electrode paste are adjusted so that the designed value of the density of the already formed negative electrode material becomes the value shown in Table 1. Except for this, a negative electrode plate is manufactured in the same manner as in the case of the lead storage battery A1, and the lead storage batteries A2 to A8 are assembled in the same manner as the lead storage battery A1 except that the obtained negative electrode plate is used.

<< Lead storage batteries B1 to B8 >>
Only carbon black (Ketjen Black (registered trademark)) is used as the carbon material. In the lead storage battery, the content of the second carbon material is 0.6% by mass. Except for these, a negative electrode plate is formed in the same manner as the lead storage battery A1. Except for using the obtained negative electrode plate, a lead storage battery B1 is assembled in the same manner as the lead storage battery A1.

  The amounts of water and dilute sulfuric acid added to the negative electrode paste are adjusted so that the designed value of the density of the already formed negative electrode material becomes the value shown in Table 1. Except for this, a negative electrode plate is manufactured in the same manner as in the case of the lead storage battery B1, and the lead storage batteries B2 to B8 are assembled in the same manner as the lead storage battery B1 except that the obtained negative electrode plate is used.

<< Lead storage batteries D1 and D2 >>
In addition to not using a carbon material in the production of the negative electrode plate, the amounts of water and dilute sulfuric acid added to the negative electrode paste are adjusted so that the design value of the density of the already formed negative electrode material becomes a value shown in Table 1. Except for these, a negative electrode plate is formed in the same manner as the lead storage battery A1. Except that the obtained negative electrode plate is used, lead storage batteries D1 and D2 are assembled in the same manner as lead storage battery A1.

<< Lead storage batteries E1 and E2 >>
Only carbon black (Ketjen Black (registered trademark)) is used as the carbon material. In the lead storage battery, the content of the second carbon material is 0.2% by mass. Except for these, a negative electrode plate is formed in the same manner as the lead storage battery D1. Except that the obtained negative electrode plate is used, a lead storage battery E1 is assembled in the same manner as the lead storage battery A1.

  A negative electrode plate is formed in the same manner as in the lead storage battery E1, except that the content of the second carbon material is set to 0.4% by mass. Except that the obtained negative electrode plate is used, a lead storage battery E2 is assembled in the same manner as the lead storage battery A1.

<< Lead storage battery E3 >>
Only carbon black (Ketjen Black (registered trademark)) is used as the carbon material. In the present lead-acid battery, the content of the second carbon material is 0.4% by mass. Except for these, a negative electrode plate is formed in the same manner as the lead storage battery D2. Except for using the obtained negative electrode plate, a lead storage battery E3 is assembled in the same manner as the lead storage battery A1.

[Evaluation 1: Applicability]
A negative electrode paste is prepared by mixing the components of the negative electrode material using a mixer (manufactured by Dalton). Then, the negative electrode paste is applied to the current collector using a paster (manufactured by Winkel). The situation at the time of application is evaluated based on the following criteria.
A: A current collector coated with the negative electrode paste is obtained at a production rate of 15 sheets or more per minute in a state where the paste does not fall off from the grids of the current collector.
B: A current collector coated with the negative electrode paste in a state where the paste did not fall off from the grids of the current collector could not be obtained at a production rate of 15 sheets or more per minute.

[Evaluation 2: Storage performance of unformed negative electrode plate]
The content of lead carbonate contained in the negative electrode material when the unformed negative electrode plate is stored is determined by the following procedure.
First, an unformed negative electrode plate is aged at a temperature of 35 ° C. and a relative humidity of 90% for 2 days, dried at 60 ° C. for 6 hours, and then stored in the air for 3 weeks. About 5 g of the negative electrode material is collected from the negative electrode plate after storage, and its mass W is measured and then pulverized. The crushed sample is immediately dropped into 50 mL of a 20% by mass aqueous solution of perchloric acid at room temperature (25 ° C.) and left for 10 minutes. The total mass m5 of the sample immediately before dropping and the aqueous solution of perchloric acid, and the total mass m6 of the sample after standing for 10 minutes and the aqueous solution of perchloric acid are measured. At this time, the mass decrease amount ΔW = m6-m5 is obtained, and the content c3 (% by mass) of lead carbonate in the negative electrode material is calculated by the following equation.
c3 = ΔW × ((M3 / M4) / W) × 100
Here, M3 is the molecular weight of lead carbonate (PbCO ₃ ), and M4 is the molecular weight of carbon dioxide (CO ₂ ). A value of M3 / M4 = 6.07 is used.

Then, based on the value of the content c3 of the carbonate, the storage performance of the unformed negative electrode plate is evaluated based on the following criteria. In addition, it shows that the one where content M of a carbonate is small is excellent in storage performance.
A: The carbonate content c3 is less than 20% by mass.
B: The carbonate content c3 is 20% by mass or more.

[Evaluation 3: cycle life performance]
A cycle life test is performed on three of the four prepared lead storage batteries. In the cycle life test, the following discharge and charge cycles are repeated in a water bath at 35 ° C. At this time, the battery is discharged at a current of 40 A at 30 ° C. every 100 cycles to a final voltage of 1.70 V, and the discharge capacity at this time is determined.
Discharge: Discharge at a current of 50 A for 3 hours.
Charging: Charge at a current of 37.5 A for 5 hours.

  The average discharge capacity is determined from the discharge capacities of the three lead-acid batteries measured every 100 cycles. The cycle life performance is evaluated based on the number of cycles T obtained as described below at a time t when the average discharge capacity falls below 75% of the nominal capacity 200 Ah (that is, 150 Ah). When the cycle number T is 1450 or more, it is determined that high cycle life performance is obtained.

The cycle number T is obtained from the average discharge capacity Q1 at the time point t when the average discharge capacity falls below 150 Ah for the first time and the average discharge capacity Q2 at the time of the discharge test 100 cycles earlier by the following equation.
T = t− (150−Q1) / (Q2−Q1) × 100

  Table 1 shows the results of the lead storage batteries A1 to A8, B1 to B8, D1 to D2, and E1 to E3. FIG. 3 shows the results of the cycle life performance among the results of A1 to A8 and B1 to B8 in Table 1.

As shown in Table 1 and FIG. 3, when the density of the negative electrode material is less than 3.8 g / cm ³ , when the second carbon material is used alone and when the powder resistance ratio is in a specific range, both carbon materials are in a specific range. The cycle life does not change so much when both are used, and all are less than 1450 cycles, which is insufficient (A1, A7, A8, B1, B7, B8). On the other hand, when the density of the negative electrode material is 3.8 g / cm ³ or more and the first carbon material and the second carbon material whose powder resistance ratio is in a specific range are combined, the content of the second carbon material is reduced. Despite the small amount, the cycle life performance comparable to the case where the second carbon material is used alone (B2 to B6) is obtained (A2 to A6). This is considered to be because many conductive networks are easily formed in the negative electrode material by combining the first carbon material and the second carbon material.

Further, as shown in Table 1, in the case of using the second carbon material alone, the density of the negative electrode material is increased (specifically, 3.7 g / cm ³ or more and 3.8 g / cm ³ or more ), The negative electrode paste cannot be applied by a machine (B1 to B6). In the batteries B1 to B6, the storage performance of the unformed negative electrode plate is low. In contrast, in the powder resistivity ratio in combination a first carbon material and the second carbon material which is a specific range, the density of the negative electrode material is 3.7 g / cm ³ or more and 3.8 g / cm ³ or more In the case of (1), application by a machine is possible (A1 to A6). This is considered to be because in the batteries A1 to A5, by satisfying the specific powder resistance ratio R2 / R1, the surface state of each carbon material is optimized, and the adsorption of the solvent is appropriately suppressed. In the battery A6, the storage performance of the unformed negative electrode plate is reduced. From the viewpoint of suppressing a decrease in storage performance, the density of the negative electrode material is preferably less than 4.7 g / cm ³ .

<< Lead storage batteries A11 to A16 >>
The addition amount of barium sulfate is adjusted so that the content of barium sulfate in the already formed negative electrode material becomes the design value shown in Table 2. Except for this, a negative electrode plate is manufactured in the same manner as in the case of the lead storage battery A3, and the lead storage batteries A11 to A16 are assembled in the same manner as the lead storage battery A1 except that the obtained negative electrode plate is used. The design value of the density of the negative electrode material in these lead storage battery and lead storage battery A3 is 4.1 g / cm ³ .

<< Lead storage batteries B11-B16 >>
The addition amount of barium sulfate is adjusted so that the content of barium sulfate in the already formed negative electrode material becomes the design value shown in Table 2. Except for this, a negative electrode plate is manufactured in the same manner as in the case of the lead storage battery B3, and the lead storage batteries B11 to B16 are assembled in the same manner as the lead storage battery A1 except that the obtained negative electrode plate is used. The design value of the density of the negative electrode material in these lead storage battery and lead storage battery B3 is 4.1 g / cm ³ .

  The lead storage batteries A11 to A16 and B11 to B16 are evaluated in the same manner as the lead storage battery A1. Further, the content of barium sulfate in the negative electrode material is measured by the procedure described above. Table 2 shows the evaluation results. Table 2 also shows the results of the lead storage batteries A3 and B3. FIG. 4 shows the results of the cycle life performance in Table 2.

  As shown in Table 2 and FIG. 4, the first carbon in which the content of barium sulfate in the negative electrode material is 0.2% by mass or more and 0.7% by mass or less and the powder resistance ratio is in a specific range. In the case where the material and the second carbon material are combined, the use of the second carbon material alone (B12 to B15, B3) is comparable to the case where the content of the second carbon material is small, and 1450 cycles The above high cycle life performance is obtained (A12 to A15, A3). The high cycle life performance of these batteries can be obtained by combining the first carbon material and the second carbon material and controlling the barium sulfate content of the negative electrode material to an appropriate range, thereby reducing the metal lead of the negative electrode plate. It is considered that lead conductivity is easily reduced at the time of charging even if deep discharge is performed without impairing the electron conductivity between particles, and charging is not hindered. From the viewpoint of obtaining higher cycle life performance, the content of barium sulfate is preferably 0.2 to 0.6% by mass.

  Further, in the lead storage batteries B11 to B16 and B3, the applicability was evaluated as B, and when mixing the components of the negative electrode material, application by a machine was not possible. Compared with these batteries, the lead-acid batteries A11 to A16 and A3 have significantly improved applicability.

<< Lead storage batteries A21-A34 >>
The amount of each carbon material used, the specific surface area, and / or an average aspect ratio, further adjusting the average particle diameter D ₅₀ of each carbon material as needed. Instead of Ketjen black, acetylene black is used in the lead storage battery A27, and activated carbon is used in the lead storage batteries A33 and A34. Thus, the powder resistance ratio R2 / R1 is changed as shown in Table 3. Except for these, a negative electrode plate is manufactured in the same manner as the lead storage battery A3. Except for using the obtained negative electrode plate, lead storage batteries A21 to A34 are assembled in the same manner as lead storage battery A1. The design value of the density of the negative electrode material in these lead-acid batteries is 4.1 g / cm ³ , as in the lead-acid battery A3.

<< Lead storage batteries A41 to A43 >>
The amount of each carbon material used, the specific surface area, and / or an average aspect ratio, further adjusting the average particle diameter D ₅₀ of each carbon material as needed. In the lead storage battery A43, acetylene black is used instead of Ketjen black. Thus, the powder resistance ratio R2 / R1 is changed as shown in Table 3. Except for these, a negative electrode plate is manufactured in the same manner as the lead storage battery A1, and the lead storage batteries A41 to A43 are assembled in the same manner as the lead storage battery A1 except that the obtained negative electrode plate is used. However, the design value of the density of the negative electrode material in these lead-acid batteries is 4.7 g / cm ³ as in the lead-acid battery A6.

  The lead storage batteries A21 to A34 and A41 to A43 are evaluated for evaluation 1 and evaluation 2 in the same manner as the lead storage battery A1. Table 3 shows the evaluation results. Table 3 also shows the results of the lead storage batteries A3 and A6.

As shown in Table 3, when the powder resistance ratio R2 / R1 is more than 15 and less than 230, high cycle life performance is obtained. Further, when it is less than 230, the applicability of the negative electrode paste is high. It is considered that high cycle life performance is obtained when the powder resistance ratio is in such a range because many conductive networks are formed in the negative electrode material. In addition, the applicability of the negative electrode paste is improved because, when the powder resistance ratio R2 / R1 is within the above range, the surface state of each carbon material is optimized and the adsorption of the solvent is appropriately suppressed. It is considered something. From the viewpoint of obtaining higher cycle life performance, the R2 / R1 ratio is preferably 80 or more and less than 230, or 80 or more and 220 or less. From the viewpoint of improving the storage performance of the unformed negative electrode plate, the density of the negative electrode material is preferably less than 4.7 g / cm ³ , and the specific surface area ratio S2 / S1 is preferably 350 or less. preferable. This is because when the specific surface area ratio S2 / S1 exceeds 350, the amount of the solvent adsorbed on the surface of the carbon material increases due to the surface state of the carbon material mixed with the paste, and sulfuric acid is required to secure the coating property. This is because root mass must be reduced.

  The lead storage battery according to one aspect of the present invention is applicable to a control valve type and a liquid type lead storage battery, such as a power supply for starting an automobile or a motorcycle, a storage of natural energy, an electric vehicle (such as a forklift), and the like. It can be suitably used as a power supply for an industrial power storage device or the like.

1: lead storage battery 2: negative electrode plate 3: positive electrode plate 4: separator 5a: negative electrode strap 5b: positive electrode strap 6a: negative electrode column 6b: positive electrode column 10: battery case 11: electrode plate group 12: electrolyte

Claims (12)

A lead-acid battery,
The lead storage battery includes a negative electrode plate and a positive electrode plate,
The negative electrode plate includes a negative electrode material containing a carbon material and barium sulfate,
The carbon material includes a first carbon material having a particle diameter of 32 μm or more, and a second carbon material having a particle diameter of less than 32 μm,
The ratio of the powder resistance R2 of the second carbon material to the powder resistance R1 of the first carbon material: R2 / R1 is more than 15 and less than 230;
The content of barium sulfate in the negative electrode material is 0.2% by mass or more and 0.7% by mass or less,
The lead-acid battery, wherein the density of the negative electrode material is 3.8 g / cm ³ or more.   The lead-acid battery according to claim 1, wherein the ratio: R2 / R1 is 80 or more and less than 230.   The lead-acid battery according to claim 1 or 2, wherein the ratio: R2 / R1 is 80 or more and 220 or less. The lead-acid battery according to any one of claims 1 to ³ , wherein the density of the negative electrode material is 4.1 g / cm3 or more. The density of the negative electrode material is less than 4.7 g / cm ^3, lead-acid battery according to any one of claims 1 to 4.   The lead storage battery according to claim 5, wherein a ratio of a specific surface area S2 of the second carbon material to a specific surface area S1 of the first carbon material: S2 / S1 is 350 or less.   The lead-acid battery according to any one of claims 1 to 6, wherein the content of barium sulfate in the negative electrode material is 0.2% by mass or more and 0.6% by mass or less.   The lead storage battery according to any one of claims 1 to 7, wherein the content of the first carbon material in the negative electrode material is 0.05% by mass or more.
The lead storage battery according to any one of claims 1 to 8, wherein the content of the first carbon material in the negative electrode material is 1.5% by mass or less.   The lead storage battery according to any one of claims 1 to 9, wherein a content of the second carbon material in the negative electrode material is 0.1% by mass or more.   The lead storage battery according to any one of claims 1 to 10, wherein a content of the second carbon material in the negative electrode material is 0.6% by mass or less.   The lead-acid battery according to any one of claims 1 to 11, wherein the first carbon material includes at least graphite, and the second carbon material includes at least carbon black.

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