阅读说明：本技术 铅蓄电池 (Lead-acid battery ) 是由 沟口泰纪 于 2018-04-25 设计创作，主要内容包括：一种铅蓄电池具备负极板、正极板和电解液,负极板含有负极电极材料,上述负极电极材料含有碳材料和有机防缩剂。碳材料包含具有32μm以上的粒径的第1碳材料和具有小于32μm的粒径的第2碳材料,第2碳材料的粉体电阻R2与第1碳材料的粉体电阻R1的比R2/R1为15～155。有机防缩剂含有木质素磺酸或其盐,负极电极材料中的有机防缩剂的含量为0.03质量％～0.8质量％。(A lead storage battery comprises a negative electrode plate, a positive electrode plate and an electrolyte, wherein the negative electrode plate contains a negative electrode material, and the negative electrode material contains a carbon material and an organic shrinkproof agent. The carbon material comprises a1 st carbon material having a particle size of 32 [ mu ] m or more and a2 nd carbon material having a particle size of less than 32 [ mu ] m, and the ratio R2/R1 of the powder resistance R2 of the 2 nd carbon material to the powder resistance R1 of the 1 st carbon material is 15 to 155. The organic shrink-proofing agent contains lignosulfonic acid or a salt thereof, and the content of the organic shrink-proofing agent in the negative electrode material is 0.03 to 0.8 mass%.)

1. A lead-acid battery in which, among others,

the lead storage battery comprises a negative electrode plate, a positive electrode plate and an electrolyte,

the negative electrode plate contains a negative electrode material containing a carbon material and an organic shrinkproof agent,

the carbon material comprises a1 st carbon material having a particle diameter of 32 [ mu ] m or more and a2 nd carbon material having a particle diameter of less than 32 [ mu ] m,

the ratio R2/R1 between the powder resistance R2 of the 2 nd carbon material and the powder resistance R1 of the 1 st carbon material is 15 to 155,

the organic shrink-proofing agent contains lignosulfonic acid or its salt,

the content of the organic shrink-proof agent in the negative electrode material is 0.03-0.8% by mass.

2. The lead-acid battery according to claim 1, wherein a ratio S2/S1 of a specific surface area S2 of the 2 nd carbon material to a specific surface area S1 of the 1 st carbon material is 20 or more.

3. The lead-acid battery according to claim 1 or 2, wherein the ratio S2/S1 of the specific surface area S2 of the 2 nd carbon material to the specific surface area S1 of the 1 st carbon material is 240 or less.

4. A lead storage battery according to any one of claims 1 to 3, wherein the 1 st carbon material has an average aspect ratio of 1.5 or more.

5. The lead-acid battery according to any one of claims 1 to 4, wherein the 1 st carbon material has an average aspect ratio of 30 or less.

6. A lead-acid battery according to any one of claims 1 to 5, wherein the negative electrode plate has a utilization rate of 40% or more.

7. A lead-acid battery according to any one of claims 1 to 6, wherein the negative electrode plate has a utilization rate of 70% or less.

8. The lead-acid battery according to any one of claims 1 to 7, wherein the content of the 1 st carbon material in the negative electrode material is 0.05 mass% or more.

9. The lead-acid battery according to any one of claims 1 to 8, wherein the content of the 1 st carbon material in the negative electrode material is 3.0 mass% or less.

10. The lead-acid battery according to any one of claims 1 to 9, wherein the content of the 2 nd carbon material in the negative electrode material is 0.03 mass% or more.

11. The lead-acid battery according to any one of claims 1 to 10, wherein the content of the 2 nd carbon material in the negative electrode material is 1.0 mass% or less.

12. The lead-acid battery according to any one of claims 1 to 11, wherein the 1 st carbon material contains at least graphite, and the 2 nd carbon material contains at least carbon black.

Technical Field

The present invention relates to a lead storage battery.

Background

Lead storage batteries can be used for various purposes other than vehicle use and industrial use. The lead storage battery includes a negative plate, a positive plate, and an electrolyte. The negative electrode plate contains a negative electrode current collector and a negative electrode material. An organic shrink-proof agent is added to the negative electrode material. For example, patent document 1 proposes that lignosulfonate be added to a negative electrode active paste material in the production of a negative electrode plate.

Disclosure of Invention

Lead storage batteries are sometimes used in an undercharged state called a partial state of charge (PSOC). For example, lead storage batteries are often used in a PSOC state when used as a power source for starting automobiles or bicycles such as charge control vehicles and Idling Stop (IS) vehicles, or as an industrial power storage device for storing natural energy such as sunlight and wind power. Therefore, high life performance in the PSOC cycle is required for the lead storage battery.

For improvement of PSOC life performance, it is effective to increase the amount of carbon black added to the negative electrode material. However, since lignin (lignosulfonic acid or a salt thereof) as an organic shrinkproof agent is adsorbed to carbon black, if a large amount of carbon black is added, the specific surface area of the negative electrode material is reduced, and the low-temperature high-rate performance is reduced. To suppress the decrease in low-temperature high-rate performance, it is considered to increase the amount of lignin. However, if a large amount of lignin is added, the charge acceptance is reduced.

In this way, it is difficult to improve the PSOC life performance without impairing the low-temperature high-rate performance and the charge acceptance performance.

One aspect of the present invention relates to a lead-acid battery including a negative electrode plate, a positive electrode plate, and an electrolyte, wherein the negative electrode plate includes a negative electrode material, the negative electrode material includes a carbon material and an organic shrinkage inhibitor, the carbon material includes a1 st carbon material having a particle size of 32 μm or more and a2 nd carbon material having a particle size of less than 32 μm, and a ratio of a powder resistance R2 of the 2 nd carbon material to a powder resistance R1 of the 1 st carbon material is: 15 to 155% of R2/R1, wherein the organic shrink-proofing agent contains lignosulfonic acid or a salt thereof, and the content of the organic shrink-proofing agent in the negative electrode material is 0.03 to 0.8% by mass.

According to the present invention, in a lead-acid battery, PSOC life performance can be improved without impairing low-temperature high-rate performance and charge acceptance performance.

Drawings

Fig. 1 is an exploded perspective view partially cut away to show the external appearance and internal structure of a lead-acid battery according to an embodiment of the present invention.

Detailed Description

One aspect of the present invention is a lead-acid battery including a negative electrode plate, a positive electrode plate, and an electrolyte. The negative electrode plate contains a negative electrode material containing a carbon material and an organic shrinkproof agent. The carbon material includes a1 st carbon material having a particle diameter of 32 [ mu ] m or more and a2 nd carbon material having a particle diameter of less than 32 [ mu ] m, and a ratio of a powder resistance R2 of the 2 nd carbon material to a powder resistance R1 of the 1 st carbon material: R2/R1 is 15 to 155. The organic shrink-proofing agent contains lignin (lignosulfonic acid or a salt thereof), and the content of the organic shrink-proofing agent in the negative electrode material is 0.03 to 0.8 mass%.

By using 2 kinds of carbon materials having different particle diameters and a specific powder resistance ratio in combination with a small amount of an organic shrinkproof agent, the life performance of the PSOC cycle can be improved. By using 2 kinds of carbon materials having different particle diameters and a specific powder resistance ratio in combination, high low-temperature high-rate performance can be maintained even when the amount of the organic shrinkproof agent added is small, i.e., 0.03 to 0.8 mass%. Since the amount of the organic shrink-proofing agent added is small, i.e., 0.8 mass% or less, it is possible to avoid a decrease in the charge acceptance due to an increase in the amount of the organic shrink-proofing agent added.

Among carbon materials, carbon materials having various powder resistances are known. It is known that the powder resistance of a powder material varies depending on the shape, particle diameter, internal structure of particles, crystallinity of particles, and the like. In the conventional technical common sense, it is considered that the powder resistance of the carbon material and the resistance of the negative plate have no direct relationship, and have no influence on the PSOC life performance and the low-temperature high-rate performance.

In contrast, according to the above-described aspect of the present invention, the 1 st carbon material and the 2 nd carbon material having different particle diameters and having a powder resistance ratio within a specific range are used in combination with a small amount of the organic shrinkproof agent, whereby the low-temperature high-rate performance can be improved. This is believed to be based on the following mechanism: when the 1 st carbon material and the 2 nd carbon material are used in combination, adsorption of the organic shrinkage-preventing agent to the carbon material can be suppressed as compared with the case where the 2 nd carbon material is increased, and the pore structure of the negative electrode material can be maintained even when the amount of the organic shrinkage-preventing agent is small.

In the above aspect of the present invention, the powder resistance ratio R2/R1 between the 1 st carbon material and the 2 nd carbon material contained in the negative electrode plate is controlled to be in the range of 15 to 155, whereby high PSOC life performance can be obtained. This is presumed to be for the following reason. First, by controlling the powder resistance ratio R2/R1 in the above range, a conductive network is easily formed in the negative electrode material. In addition, even if the amount of the organic shrinkproof agent is small, the effect of the organic shrinkproof agent can be sufficiently exhibited, and the pore structure of the negative electrode material can be maintained. Thus, the formed conductive network is easily maintained even with PSOC cycling. That is, by combining the 1 st carbon material and the 2 nd carbon material having the powder resistance ratio as described above, the effect of the organic shrinkproof agent can be improved.

(organic shrinkproof agent)

The organic shrinkproof agent contains lignin (lignosulfonic acid or a salt thereof). Examples of the salt of lignin sulfonic acid include alkali metal salts such as sodium salts. The lignin also includes derivatives thereof. For example, a product name "vanilex N" manufactured by japan paper-making co.

The content of the organic shrink-proof agent in the negative electrode material is 0.03-0.8 mass%. When the content of the organic shrinkproof agent in the negative electrode material is less than 0.03 mass%, the low-temperature high-rate performance is reduced. When the content of the organic shrinkproof agent in the negative electrode material is more than 0.8 mass%, the charge acceptance is lowered. The content of the organic shrinkage-preventing agent in the negative electrode material is a content of the negative electrode material collected from the lead-acid battery in a fully charged state after the formation by a method described later.

The content of the organic shrink preventing agent in the negative electrode material is preferably 0.03 mass% or more, and more preferably 0.25 mass% or more. Further, it is preferably 0.4% by mass or less. These upper and lower limits may be arbitrarily combined. In this case, excellent PSOC life performance, low-temperature high-rate performance, and charge acceptance performance can be obtained in a well-balanced manner.

The method of analyzing the organic shrinkproof agent and the method of determining the physical properties will be described below.

(A) Analysis of organic shrink-proofing Agents

(A-1) specifying the kind of organic shrinkproof agent

The kind of the organic shrinkproof agent in the negative electrode material was specified as follows.

The fully charged lead-acid battery was decomposed, and the negative electrode plate was taken out, washed with water to remove the sulfuric acid component, and vacuum-dried (dried under a pressure lower than atmospheric pressure). The negative electrode material containing the active material was separated from the negative electrode plate, and the negative electrode material was immersed in a 1mol/L aqueous NaOH solution to extract the organic anti-shrinkage agent. Then, a solution obtained by removing insoluble components from the extract solution by filtration was desalted and freeze-dried (lyophilized) to obtain a powder sample. Desalting column and ion exchange membrane are used for desalting. The kind of the organic shrinkproof agent is determined from information obtained from an infrared spectrum and an NMR spectrum measured from a powder sample using the organic shrinkproof agent thus obtained, and an ultraviolet-visible absorption spectrum obtained by further diluting the powder sample with distilled water and measuring the diluted powder sample with an ultraviolet-visible absorption spectrometer.

In the present specification, in the case of a liquid battery, the fully charged state of a lead acid battery is a state in which the lead acid battery is subjected to constant current charging at 0.2CA in a 25 ℃ water tank until the battery reaches 2.5V/Cell, and then is subjected to constant current charging at 0.2CA for 2 hours. In the case of a valve-regulated battery, the fully charged state is a state in which constant-current constant-voltage charging of 2.23V/Cell is performed at 0.2CA in a gas tank at 25 ℃, and the charging is terminated when the charging current in constant-voltage charging becomes 1mCA or less.

In the present specification, 1CA means a current value (a) having the same value as the nominal capacity (Ah) of the battery. For example, if the battery is a battery with a nominal capacity of 30Ah, 1CA is 30A and 1mCA is 30 mA.

(A-2) measurement of content of organic shrinkproof agent

The content of the organic shrinkproof agent in the negative electrode material was measured as follows.

The fully charged lead-acid battery was decomposed, and the negative electrode plate was taken out, washed with water to remove the sulfuric acid component, and vacuum-dried (dried under a pressure lower than atmospheric pressure). The negative electrode material was separated from the negative electrode plate, and 100g of the negative electrode material was immersed in 300mL of a 1mol/L NaOH aqueous solution to extract the organic shrinkproof agent. Then, after insoluble components were removed from the extract by filtration, the ultraviolet-visible absorption spectrum was measured, and the content of the organic shrinkproof agent in the negative electrode material was measured using a calibration curve prepared in advance.

When a battery manufactured by another company is obtained and the content of the synthetic shrinkproof agent is measured, the structural formula of the organic shrinkproof agent cannot be specified precisely and the same organic shrinkproof agent cannot be used for a calibration curve, and in this case, a calibration curve is prepared using an organic shrinkproof agent that can be obtained by another route and shows a shape similar to that of the organic shrinkproof agent extracted from the negative electrode of the battery, such as an ultraviolet-visible absorption spectrum, an infrared spectrum, and an NMR spectrum, and the content of the organic shrinkproof agent is measured using the visible absorption spectrum.

(carbon Material)

The carbon material includes a1 st carbon material having a particle diameter of 32 μm or more and a2 nd carbon material having a particle diameter of less than 32 μm. The 1 st carbon material and the 2 nd carbon material are separated and distinguished by the steps described later.

Examples of the carbon material include carbon black, graphite, hard carbon, and soft carbon. Examples of the carbon black include acetylene black, ketjen black, furnace black, and lamp black. The graphite may be any of artificial graphite and natural graphite as long as it is a carbon material having a graphite-type crystal structure.

In addition, in the 1 st carbon material, 1300cm in Raman spectrum^-1～1350cm^-1Range of (1)The peak (D band) appeared at 1550cm^-1～1600cm^-1Intensity ratio I of the peak (G band) appearing in the range of (1)_D/I_G0 to 0.9 carbon material as graphite.

Ratio of powder resistance R2 of the 2 nd carbon material to powder resistance R1 of the 1 st carbon material: R2/R1 is 15 to 155. The larger the powder resistance ratio R2/R1, the smaller the amount of lignin adsorbed to the carbon material. When the powder resistance ratio R2/R1 is less than 15, the low-temperature high-rate performance is lowered. When the powder resistance ratio R2/R1 is more than 155, the charge acceptance is lowered. R2/R1 can be adjusted by changing, for example, the kind, particle diameter, specific surface area, aspect ratio, and the like of each carbon material used for production of the negative electrode material. As the 1 st carbon material, for example, at least 1 selected from graphite, hard carbon and soft carbon is preferable. Particularly preferably, the 1 st carbon material contains at least graphite. Preferably, the 2 nd carbon material contains at least carbon black. When these carbon materials are used, the powder resistance ratio R2/R1 can be easily adjusted.

The powder resistance ratio R2/R1 is preferably 50 to 110. In this case, excellent PSOC life performance, low-temperature high-rate performance, and charge acceptance performance can be obtained in a well-balanced manner. When the powder resistance ratio R2/R1 is 50 or more, the PSOC life performance and the charge acceptance performance can be further improved. When the powder resistance ratio R2/R1 is 110 or more, the PSOC life performance and the low-temperature high-rate performance can be further improved.

When the content of the organic shrinkage-preventing agent in the negative electrode material is 0.03 to 0.25 mass%, the powder resistance ratio R2/R1 is preferably 80 to 155, and more preferably 80 to 110. When the content of the organic shrinkage-preventing agent in the negative electrode material is 0.4 to 0.8 mass%, the powder resistance ratio R2/R1 is preferably 15 to 85, and more preferably 50 to 85. When the content range of the organic shrinkproof agent in the negative electrode material is combined with the range of the powder resistance ratio R2/R1, the PSOC life performance can be further improved.

Ratio of specific surface area S2 of the 2 nd carbon material to specific surface area S1 of the 1 st carbon material: S2/S1 is, for example, 10 to 400 inclusive. The specific surface area ratio S2/S1 is preferably 20 to 240. In this case, excellent PSOC life performance, low-temperature high-rate performance, and charge acceptance performance can be obtained in a well-balanced manner. When the specific surface area ratio S2/S1 is 20 or more, the PSOC life performance can be further improved. When the specific surface area ratio S2/S1 is 240 or less, the specific surface area of each carbon material is in an appropriate range, and adsorption of the organic anti-shrink agent can be further suppressed, so that the low-temperature high-rate performance is further improved. When the specific surface area ratio S2/S1 is 20 to 240, the reduction reaction of lead sulfate is easily performed, so that the high PSOC life performance can be ensured, and the charge acceptance performance is further improved. The specific surface area ratio S2/S1 is preferably 100 to 240, and more preferably 110 to 240. In this case, the PSOC lifetime performance and the charge acceptance performance can be further improved while maintaining the low-temperature high-rate performance.

The average aspect ratio of the 1 st carbon material is, for example, 1 or more and 200 or less. The average aspect ratio of the carbon material 1 is preferably 1 or more, and more preferably 1.5 or more. Further, it is preferably 100 or less, more preferably 35 or less, and further preferably 30 or less. These upper and lower limits may be arbitrarily combined. When the average length-diameter ratio of the 1 st carbon material is 1.5 to 30, the good low-temperature high-rate performance and charge acceptance performance can be maintained, and the PSOC service life performance can be further improved. This is believed to be based on the following mechanism: when the average aspect ratio is in such a range, a conductive network is easily formed in the negative electrode material, and the formed conductive network is easily maintained.

When the average aspect ratio of the 1 st carbon material is 1.5 or more, the carbon material can be inhibited from flowing out into the electrolyte solution due to repetition of charge and discharge, and the effect of improving the PSOC lifetime performance can be further increased. In addition, when the average aspect ratio of the 1 st carbon material is 30 or less, the adhesion between the active material particles is easily ensured, and therefore, the occurrence of cracks in the negative electrode plate can be suppressed, and the deterioration of the life performance can be suppressed.

The content of the 1 st carbon material in the negative electrode material is, for example, 0.05 to 3.0 mass%, preferably 0.1 mass% or more, and more preferably 0.4 mass% or more. Further, it is preferably 2.0 mass% or less. These upper and lower limits may be arbitrarily combined. When the content of the 1 st carbon material in the negative electrode material is 0.05 mass% or more, the PSOC life performance can be further improved. When the content of the 1 st carbon material in the negative electrode material is 3.0 mass% or less, the adhesion between the active material particles is easily ensured, the occurrence of cracks in the negative electrode plate can be suppressed, and the deterioration of the life performance can be suppressed.

The content of the 2 nd carbon material in the negative electrode material is, for example, 0.03 to 3.0 mass%, and preferably 0.05 mass% or more. Further, it is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. These upper and lower limits may be arbitrarily combined. When the content of the 2 nd carbon material in the negative electrode material is 0.03 mass% or more, the PSOC life performance can be further improved. When the content of the 2 nd carbon material in the negative electrode material is 3.0 mass% or less, the amount of adsorption of the organic shrinkproof agent can be further reduced, and the low-temperature high-rate performance can be further improved.

The content of each carbon material in the negative electrode material was determined in accordance with the procedure (B-1) described later.

The method of determining the physical properties of the carbon material or the method of analyzing the same will be described below.

(B) Analysis of carbon Material

(B-1) separation of carbon Material

The fully charged lead-acid battery is decomposed, and the resultant negative electrode plate is taken out, washed with water to remove sulfuric acid, and vacuum-dried (dried under a pressure lower than atmospheric pressure). Next, the negative electrode material is collected from the dried negative electrode plate and pulverized. 30mL of a 60 mass% nitric acid aqueous solution was added to 5g of the pulverized sample, and the mixture was heated at 70 ℃. Further, 10g of disodium ethylenediaminetetraacetate, 30mL of 28 mass% aqueous ammonia and 100mL of water were added thereto, and heating was continued to dissolve soluble substances. The sample thus pretreated was collected by filtration. The collected sample was passed through a sieve having a mesh size of 500 μm to remove large-sized components such as reinforcing materials, and the components passing through the sieve were collected as a carbon material.

When the collected carbon material is wet-sieved using a sieve having a mesh size of 32 μm, the carbon material that does not pass through the mesh size of the sieve and remains on the sieve is referred to as a1 st carbon material, and the carbon material that passes through the mesh size of the sieve is referred to as a2 nd carbon material. That is, the particle diameter of each carbon material is based on the size of the mesh of the sieve. Wet screening may be performed according to JIS Z8815: 1994.

specifically, the carbon material was placed on a sieve having a mesh size of 32 μm, and the sieve was gently shaken for 5 minutes to perform sieving while dispersing ion-exchanged water. The 1 st carbon material remaining on the screen is collected from the screen by passing ion-exchanged water therethrough, and separated from the ion-exchanged water by filtration. The 2 nd carbon material having passed through the screen was collected by filtration using a membrane filter (mesh size 0.1 μm) made of nitrocellulose. The recovered 1 st carbon material and 2 nd carbon material were dried at a temperature of 110 ℃ for 2 hours, respectively. As a sieve having a mesh size of 32 μm, a sieve having a mesh size of JIS Z8801-1: a sieve having a mesh with a nominal mesh size of 32 μm as defined in 2006.

The content of each carbon material in the negative electrode material was determined by measuring the mass of each carbon material separated in the above-described step and calculating the ratio (% by mass) of the mass to 5g of the pulverized sample.

(B-2) powder resistance of carbon Material

The powder resistance R1 of the 1 st carbon material and the powder resistance R2 of the 2 nd carbon material are values measured by: for each of the carbon material 1 and the carbon material 2 separated in the step (B-1), 0.5g of a sample was put into a powder resistance measuring system (MCP-PD 51, manufactured by Mitsubishi Chemical Analytech co., ltd.) and the mixture was subjected to a pressure of 3.18MPa under the conditions of the following conditions in accordance with JIS K7194: 1994 (manufactured by Mitsubishi chemical Analytech, Loresta GX MCP-T700), by the four-probe method.

(B-3) specific surface area of carbon Material

The specific surface areas S1 and S2 of the 1 st carbon material and the 2 nd carbon material are BET specific surface areas of the 1 st carbon material and the 2 nd carbon material, respectively. The BET specific surface area was determined by the BET formula using the 1 st carbon material and the 2 nd carbon material separated in the step (B-1) by a gas adsorption method. Each carbon material was pretreated by heating at 150 ℃ for 1 hour in a nitrogen stream. Using the pretreated carbon material, the BET specific surface area of each carbon material was determined by the following apparatus under the following conditions.

A measuring device: TriStar3000 manufactured by Micromeritics

Adsorbing gas: nitrogen with purity over 99.99 percent

Adsorption temperature: boiling point temperature of liquid nitrogen (77K)

Method for calculating BET specific surface area: based on JIS Z8830: 2013 7.2

(B-4) average aspect ratio of carbon Material 1

The 1 st carbon material separated in the step (B-1) was observed with an optical microscope or an electron microscope, and any particle having 10 or more particles was selected and a magnified photograph thereof was taken. Next, the image of each particle was processed to determine the maximum particle diameter d1 of the particle and the maximum particle diameter d2 in the direction orthogonal to the maximum particle diameter d1, and the d1 was divided by d2 to determine the aspect ratio of each particle. The average aspect ratio was calculated by averaging the obtained aspect ratios.

The utilization rate of the negative electrode plate is preferably 40% to 70%, and more preferably 50% or more. Further, it is preferably 70% or less, and more preferably 65% or less. These upper and lower limits may be arbitrarily combined.

By improving the utilization rate of the negative plate, the amount of the negative active material can be reduced, and the cost is reduced. However, since the negative electrode active material is arbitrarily used during charge and discharge, deterioration of the negative electrode plate due to sulfation or the like is likely to progress, and battery performance such as low-temperature high-rate performance and PSOC life performance tends to be lowered.

On the other hand, even when the utilization rate of the negative electrode plate is high, battery performance such as PSOC life performance can be greatly improved by using a negative electrode material containing a small amount of lignin in a specific range and 2 kinds of carbon materials having different particle diameters and a powder resistance ratio in a specific range. For example, when the yield of the negative electrode plate is increased to 50% or more, the powder resistance ratio R2/R1 is increased to 100 or more, whereby the effects of improving the low-temperature high-rate performance and the PSOC life performance can be more remarkably obtained.

(C) The method for measuring the utilization rate of the negative electrode plate will be described below.

The yield of the negative electrode plate was determined by the following equation.

Utilization ratio (%) of the negative electrode plate (nominal capacity/theoretical capacity of negative electrode) × 100

The theoretical capacity of the negative electrode is determined by the following equation.

Theoretical capacity of negative electrode (Ah) ═ mass (g) of negative electrode active material in negative electrode plate x theoretical capacity (Ah) of negative electrode active material per 1g

The theoretical capacity of the negative electrode active material (Pb) per 1g was 0.259 Ah. The smaller the mass of the negative electrode active material is, the higher the utilization rate of the negative electrode is.

The mass of the negative electrode active material in the negative electrode plate was determined by the following procedure.

First, the battery in a fully charged state is disassembled to obtain a negative electrode plate, and after washing with water and vacuum drying (drying under a pressure lower than atmospheric pressure), the mass of the negative electrode plate is measured. Thereafter, the negative electrode material containing the negative electrode active material was separated from the negative electrode plate, and the mass of the remaining negative electrode current collector (negative electrode grid) was measured. The difference between the mass of the negative electrode plate and the mass of the negative grid was obtained as the mass of the negative electrode material.

The negative electrode material separated from the negative electrode plate was pulverized, 20mL of an aqueous hydrogen peroxide solution (concentration: 300g/L) was added per 100g of the negative electrode material, and nitric acid was further added thereto and heated with stirring for 5 hours. Thus, lead contained in the negative electrode material is dissolved as lead nitrate. The nitric acid was used after diluting concentrated nitric acid (concentration: 60 mass%) with ion-exchanged water. The volume ratio of the concentrated nitric acid to the ion exchange water is 1: 3. next, the additives (carbon material, organic shrink-proofing agent, barium sulfate, reinforcing material, etc.) remaining without being dissolved in nitric acid were separated by filtration, washed with water, dried, and then the mass of the additives was measured. The difference between the mass of the negative electrode material and the mass of the additive was determined as the mass of the negative electrode active material.

Hereinafter, the lead-acid battery according to the embodiment of the present invention will be described with respect to the main constituent elements, but the present invention is not limited to the following embodiment.

(negative plate)

The negative electrode plate of the lead storage battery contains a negative electrode material. The negative electrode plate may be generally composed of a negative electrode grid (negative electrode collector) and a negative electrode material. The negative electrode material is obtained by removing the negative current collector from the negative electrode plate.

A pad, a water absorbing paper (blotting paper), or the like may be attached to the negative electrode plate. When the negative electrode plate includes such a member (attached member), the negative electrode material refers to a portion other than the negative electrode current collector and the attached member. Wherein, the thickness of the electrode plate is the thickness containing the pad. When the spacer is attached with the mat, the thickness of the mat is included in the thickness of the spacer.

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

The content of barium sulfate in the negative electrode material is, for example, preferably 0.1 mass% or more, more preferably 0.2 mass% or more, and may be 0.5 mass% or more, may be 1.0 mass% or more, and may be 1.3 mass% or more. On the other hand, it is preferably 3.0% by mass or less, more preferably 2.5% by mass or less, and further preferably 2% by mass or less. These lower limit value and upper limit value may be arbitrarily combined.

Hereinafter, a method for quantifying barium sulfate contained in the negative electrode material is described. Before quantitative analysis, the lead-acid battery after formation is fully charged and then disassembled to obtain a negative electrode plate to be analyzed. The obtained negative electrode plate was washed with water and dried to remove the electrolyte from the negative electrode plate. Next, the negative electrode material was separated from the negative electrode plate to obtain an initial sample without pulverization.

An initial sample which was not pulverized was pulverized, and 50ml of (1+2) nitric acid was added to 10g of the pulverized initial sample, and the mixture was heated for about 20 minutes to dissolve the lead component as lead nitrate. Next, the solution containing lead nitrate was filtered to remove solid components such as carbonaceous materials and barium sulfate.

After the obtained solid content was dispersed in water to prepare a dispersion, components (for example, a reinforcing material) other than the carbonaceous material and barium sulfate were removed from the dispersion by using a sieve. Next, the dispersion was subjected to suction filtration using a membrane filter whose mass was measured in advance, and the membrane filter was dried together with the filtered sample in a dryer at 110 ℃. The filtered sample is a mixed sample of carbonaceous material and barium sulfate. The mass (a) of the mixed sample was measured by subtracting the mass of the membrane filter from the total mass of the dried mixed sample and the membrane filter. Thereafter, the dried mixed sample was put in a crucible together with a membrane filter, and was incinerated at 700 ℃ or higher. The residue remained as barium oxide. The mass of barium sulfate was determined by converting the mass of barium oxide to the mass of barium sulfate (B).

The density of the negative electrode material can be, for example, 2.4 to 5g/cm³The range of (3) is adjusted. The density of the negative electrode material is preferably 2.4 to 4.0g/cm from the viewpoint of weight reduction of the lead-acid battery³。

The density of the negative electrode material is a value of the bulk density of the negative electrode material in a fully charged state after the conversion, and is measured as follows. The battery after formation is fully charged and then disassembled, and the obtained negative electrode plate is washed with water and dried under vacuum or an inert gas atmosphere, thereby removing the electrolyte in the negative electrode plate. Next, the negative electrode material was separated from the negative electrode plate to obtain an unpulverized measurement sample. A sample is put into a measuring container, vacuum-exhausted, then filled with mercury at a pressure of 0.5 to 0.55psia, the stacking volume of the negative electrode material is measured, and the mass of the measured sample is divided by the stacking volume to determine the stacking density of the negative electrode material. The volume obtained by subtracting the injection volume of mercury from the volume of the measurement container is defined as the deposition volume.

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 wire drawing and punching (piercing).

The lead alloy used for the negative electrode 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 1 kind selected from Ba, Ag, Al, Bi, As, Se, Cu, and the like As an additive element.

The negative electrode plate can be formed by filling a negative electrode paste into a negative electrode current collector, aging and drying the negative electrode paste to produce an unformed negative electrode plate, and then forming the unformed negative electrode plate. The negative electrode paste can be prepared by adding water and sulfuric acid to lead powder, an organic shrinkproof agent, a carbon material, and, if necessary, various additives, and kneading them.

The formation may be performed by charging the non-formed negative electrode plate in a state of being immersed in an electrolytic solution containing sulfuric acid. The formation may be performed in the battery case after the lead-acid battery is assembled, or a formation tank for storing the electrolyte may be separately prepared and performed before the lead-acid battery or the electrode plate group is assembled.

(Positive plate)

Positive electrode plates for lead-acid batteries are of the pasted type and the clad type.

The paste-type positive electrode plate is provided with a positive electrode collector and a positive electrode material. The positive electrode material is held by the positive current collector. The positive electrode current collector may be formed in the same manner as the negative electrode current collector, and may be formed by casting lead or a lead alloy, or processing a lead or a lead alloy sheet.

The clad positive electrode plate includes a plurality of porous tubes, a core rod inserted into each tube, a current collecting portion connected to the core rod, a positive electrode material filled into the tubes into which the core rod is inserted, and a connection base connecting the plurality of tubes. The mandrel and the current collecting portion to which the mandrel is connected 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 alloy, a Pb — Sb alloy, and a Pb — Ca — Sn alloy. The lead alloy may further contain at least 1 kind selected from Ba, Ag, Al, Bi, As, Se, and Cu As an additive element. The positive electrode current collector may have lead alloy layers having different compositions, and the number of the alloy layers may be plural. As the plug, a Pb-Ca alloy, a Pb-Sb alloy, or the like is used.

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

The unformed pasted positive electrode plate can be obtained by filling a positive electrode current collector with a positive electrode paste prepared by adding lead powder, various additives, water, and sulfuric acid, aging, and drying. In the case of aging, the uncured positive electrode plate is preferably aged at a temperature higher than room temperature and at a high humidity. Thereafter, the unformed positive electrode plate is formed.

The clad positive electrode plate can be formed by filling a tube into which a core rod is inserted with lead powder or slurry-like lead powder, and joining a plurality of tubes with a connecting base.

(spacer)

A separator is generally disposed between the negative electrode plate and the positive electrode plate. The separator is made of a nonwoven fabric, a microporous film, or the like. The thickness and the number of the separators sandwiched between the negative and positive electrode plates may be selected according to the inter-electrode distance.

The nonwoven fabric is a mat formed by winding fibers without weaving, and mainly includes 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 fiber is preferable. The nonwoven fabric may contain components other than fibers, such as 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, and can be obtained, for example, by extrusion-molding a composition containing a pore-forming agent (polymer powder, oil, or the like) into a sheet shape, and then removing the pore-forming agent to form pores. The microporous membrane is preferably made of a material having acid resistance, and preferably mainly contains a polymer component. As the polymer component, polyolefins such as polyethylene and polypropylene are preferable.

The separator may be composed of only a nonwoven fabric or only a microporous film, for example. The separator may be a laminate of a nonwoven fabric and a microporous film, a laminate of different types or the same type of materials with irregularities embedded therein, or the like, as required.

(electrolyte)

The electrolyte is an aqueous solution containing sulfuric acid, and can be gelled as necessary. The specific gravity of the electrolyte in the lead storage battery in a fully charged state after formation at 20 ℃ is, for example, 1.10 to 1.35g/cm³Preferably 1.20 to 1.35g/cm³。

Fig. 1 shows an external appearance of an example of a lead-acid battery according to an embodiment of the present invention.

The lead storage battery 1 includes a battery case 12 that accommodates an electrode group 11 and an electrolyte (not shown). The battery case 12 is divided into a plurality of battery cell chambers 14 by partitions 13. Each cell chamber 14 accommodates 1 electrode group 11. The opening of the battery case 12 is sealed by a lid 15 provided with a negative electrode terminal 16 and a positive electrode terminal 17. A liquid port plug 18 is provided on the cover 15 for each cell chamber. When water is replenished, the liquid port plug 18 is opened to replenish the replenishing liquid. The liquid port plug 18 may have a function of discharging gas generated in the cell chamber 14 to the outside of the battery.

The electrode group 11 is formed by laminating a plurality of negative electrode plates 2 and positive electrode plates 3 with separators 4 interposed therebetween. Here, the bag-like separator 4 that houses the negative electrode plate 2 is shown, but the form of the separator is not particularly limited. In a battery cell chamber 14 located at one end of the battery case 12, a negative electrode housing portion 6 in which the lug portions 2a of the plurality of negative electrode plates 2 are connected in parallel is connected to the penetration connector 8, and a positive electrode housing portion 5 in which the lug portions 3a of the plurality of positive electrode plates 3 are connected in parallel is connected to the positive electrode post 7. The positive post 7 is connected to a positive terminal 17 on the outside of the cover 15. In the battery cell chamber 14 located at the other end of the battery container 12, the negative electrode housing portion 6 is connected to the negative electrode post 9, and the positive electrode housing portion 5 is connected to the penetration connector 8. The negative electrode tab 9 is connected to a negative electrode terminal 16 on the outside of the cover 15. Each of the through-connectors 8 connects the electrode groups 11 of the adjacent battery cell chambers 14 in series through-holes provided in the partition walls 13.

The lead-acid battery according to one aspect of the present invention is summarized below.

(1) One aspect of the present invention is a lead-acid battery in which,

the lead storage battery comprises a negative electrode plate, a positive electrode plate and an electrolyte,

the negative electrode plate contains a negative electrode material containing a carbon material and an organic shrinkproof agent,

the carbon material comprises a1 st carbon material having a particle diameter of 32 [ mu ] m or more and a2 nd carbon material having a particle diameter of less than 32 [ mu ] m,

a ratio of the powder resistance R2 of the 2 nd carbon material to the powder resistance R1 of the 1 st carbon material: R2/R1 is 15 to 155,

the organic shrink-proofing agent contains lignosulfonic acid or its salt,

the content of the organic shrinkproof agent in the negative electrode material is 0.03 to 0.8 mass%.

(2) In the above (1), a ratio of the specific surface area S2 of the 2 nd carbon material to the specific surface area S1 of the 1 st carbon material: S2/S1 is preferably 20 or more.

(3) In the above (1) or (2), a ratio of the specific surface area S2 of the 2 nd carbon material to the specific surface area S1 of the 1 st carbon material: S2/S1 is preferably 240 or less.

(4) In any one of the above (1) to (3), the 1 st carbon material preferably has an average aspect ratio of 1.5 or more.

(5) In any one of the above (1) to (4), the 1 st carbon material preferably has an average aspect ratio of 30 or less.

(6) In any one of the above (1) to (5), the utilization rate of the negative electrode plate is preferably 40% or more.

(7) In any one of the above (1) to (6), the utilization rate of the negative electrode plate is preferably 70% or less.

(8) In any one of the above (1) to (7), the content of the 1 st carbon material in the negative electrode material is preferably 0.05% by mass or more.

(9) In any one of the above (1) to (8), the content of the 1 st carbon material in the negative electrode material is preferably 3.0% by mass or less.

(10) In any one of the above (1) to (9), the content of the 2 nd carbon material in the negative electrode material is preferably 0.03 mass% or more.

(11) In any one of the above (1) to (10), the content of the 2 nd carbon material in the negative electrode material is preferably 1.0 mass% or less.

(12) In any one of the above (1) to (11), it is preferable that the 1 st carbon material contains at least graphite, and the 2 nd carbon material contains at least carbon black.