HK40044131A - Negative electrode for lead storage battery, and lead storage battery - Google Patents

Description

Negative electrode for lead-acid battery and lead-acid battery

Technical Field

The present invention relates to a negative electrode for a lead-acid battery and a lead-acid battery.

Background

Lead storage batteries are widely used in various applications such as in-vehicle applications and industrial applications. For example, a lead acid battery for vehicle mounting can be used as a power source for driving a battery motor and a power source for electric equipment in a vehicle.

In lead storage batteries, additives such as carbon are generally added to the negative electrode active material in order to improve various performances (see patent document 1). Patent document 1 proposes a lead-acid battery in which a sodium lignosulfonate, barium sulfate, and oil furnace carbon black are added to a negative electrode active material.

Documents of the prior art

Patent document

Patent document 1, Japanese patent laid-open No. 2008-152955

Disclosure of Invention

In recent years, systems for idling stop of an engine have been widely used for the purpose of improving fuel efficiency of automobiles. In a lead-acid battery provided in an automobile (idling stop vehicle) using these systems, the frequency of charging and discharging is higher than that of a power storage element provided in a conventional automobile. Further, it is required that more electric power can be charged in a shorter time. In this way, it is required that the lead-acid battery for the idling stop vehicle can be efficiently charged. However, the conventional lead-acid battery cannot sufficiently satisfy the requirement. Here, as an idle stop life test, for example, a test method of repeating charge and discharge for a predetermined short time is defined in the battery industry agency specification SBA S0101. If the charging efficiency is low, the discharge voltage is reduced more rapidly and the life is shortened in such an idle stop life test.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a negative electrode for a lead-acid battery capable of improving the charging efficiency of the lead-acid battery, and a lead-acid battery having excellent charging efficiency.

One embodiment of the present invention made to solve the above problems is a negative electrode (a) for a lead-acid battery, which has a negative electrode mixture containing lead, and in an X-ray diffraction spectrum of the negative electrode mixture present on the surface, a ratio of a peak height at a diffraction angle of 30.3 ° to a peak height at a diffraction angle of 31.2 ° is 0.05 or more.

Another embodiment of the present invention is a negative electrode (B) for a lead-acid battery, which has a negative electrode mixture containing lead, wherein at least a part of the negative electrode mixture present on the surface has a scaly shape, and the aspect ratio of the scaly shape is 3 to 10.

Still another aspect of the present invention is a lead-acid battery including the negative electrode (a) for a lead-acid battery or the negative electrode (B) for a lead-acid battery.

According to the present invention, a negative electrode for a lead-acid battery capable of improving the charging efficiency of the lead-acid battery and a lead-acid battery having good charging efficiency can be provided.

Drawings

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

Fig. 2 is an X-ray diffraction spectrum of the negative electrode mixture present on the surface in the lead-acid battery of example 4.

Fig. 3 is an X-ray diffraction spectrum of the negative electrode mixture present on the surface in the lead-acid battery of comparative example 5.

Fig. 4 is an electron micrograph of a negative electrode mixture on the surface of the lead-acid battery of example 4.

Fig. 5 is an electron micrograph of a negative electrode mixture on the surface of the lead-acid battery of comparative example 5.

Detailed Description

A negative electrode for a lead-acid battery according to an embodiment of the present invention is a negative electrode (a) for a lead-acid battery, which has a negative electrode mixture containing lead, and in an X-ray diffraction spectrum of the negative electrode mixture present on the surface, a ratio of a peak height at a diffraction angle of about 30.3 ° to a peak height at a diffraction angle of about 31.2 ° is 0.05 or more.

The negative electrode (A) for a lead-acid battery can improve the charging efficiency of the lead-acid battery. The reason is not clear, but the following reason is presumed. It is known that lead sulfate, which is coarsened in the negative electrode mixture by repeated charge and discharge, is one of the causes of deterioration in charge acceptance and the like. Lead sulfate existing in the negative electrode mixture or on the surface of the negative electrode mixture is reduced during charging and eluted into the electrolyte, and the lead sulfate becomes difficult to reduce and elute with repetition of charging and discharging, and coarsens. Therefore, it is considered that if the negative electrode mixture is formed into a shape in which lead sulfate is easily reduced and eluted, the coarsening of lead sulfate is suppressed, and the charging efficiency is improved. Here, the inventors found that when a negative electrode mixture containing lead is formed into a scaly shape (a shape of a scaly protrusion), a peak near a diffraction angle of 30.3 ° appears in an X-ray diffraction spectrum. When the negative electrode mixture present on the surface contains such a scaly shape, lead sulfate is generated in narrow gaps of the scaly shape, and therefore, it is difficult to coarsen the negative electrode mixture. Further, the electrolyte penetrates into the gaps in the scale-like shape, and therefore the area of contact between the generated lead sulfate and the electrolyte is large. Therefore, it is presumed that, when the negative electrode (a) for a lead storage battery is used, lead sulfate formed in the negative electrode is easily reduced and dissolved at the time of reduction, and the charging efficiency can be improved. In other words, since the peak near 30.3 ° corresponds to lead oxide, it is also presumed that, regardless of whether or not the negative electrode mixture is formed into a scaly shape, the presence of lead oxide in the negative electrode mixture present on the surface itself makes lead sulfate, for example, easily reduced, and thus contributes to improvement of the charging efficiency.

The surface of the negative electrode for a lead acid battery is a surface facing the positive electrode in an assembled state of the lead acid battery, and the negative electrode mixture present on the surface is a negative electrode mixture exposed on the surface facing the positive electrode. In the present specification, the X-ray diffraction spectrum of the negative electrode mixture present on the surface is a value measured by the following method.

I. Pretreatment

First, the lead storage battery is brought into a fully charged state (SOC 100%). The charging conditions for bringing the lead storage battery into a fully charged state are as follows. In the case of a liquid (vented) battery, the battery was charged at a constant current of 0.2C in a water tank at 25 ℃ until 2.5V/cell, and then further charged at a constant current of 0.2C for 2 hours. In the case of a valve-regulated (sealed) battery, constant-current constant-voltage charging of 0.2C and 2.23V/cell was carried out at 25 ℃ in a gas cell, and the charging was terminated when the charging current in the constant-voltage charging was 1mC or less. Note that 1C is a current value at which the nominal capacity of the battery is discharged in 1 hour, and for example, if the battery has a nominal capacity of 30Ah, 1C is 30A. The lead acid battery in a fully charged state was decomposed, and the negative electrode was taken out and washed with running water for 4 hours. Thereafter, the mixture was dried under vacuum at a drying temperature of 70 ℃ and a vacuum degree of about 150kPa for 12 hours.

Determination of

For the negative electrode subjected to the above pretreatment, the surface thickness was measured at 1cm by a spatula²The negative electrode mix was collected in an amount of 0.048g and ground in a mortar. The ground negative electrode mixture 2g was filled on a sample table and measured. The measurement conditions were as follows.

Measurement machine: smart Lab horizontal goniometer model theta-theta manufactured by Rigaku Corporation

Target: cu

Voltage/current: 40kV/30mA

A detector: dtex250(H)

X-ray diffraction Pattern determination

Scanning mode: continuous Scan

Measuring an angle: 2 theta is 20-60 DEG

Scanning speed: 10 °/min

Scanning step length: 0.02 degree

A negative electrode for a lead-acid battery according to another embodiment of the present invention is a negative electrode (B) for a lead-acid battery, which has a negative electrode mixture containing lead, at least a part of the negative electrode mixture present on the surface has a scaly shape, and the aspect ratio of the scaly shape is 3 to 10. The negative electrode (B) for a lead-acid battery can improve the charging efficiency of the lead-acid battery. The reason is not clear, but is assumed to be the same as in the negative electrode (a) for a lead-acid battery.

In the present specification, the scale-like shape means only a thin shape, and the planar shape thereof is not particularly limited. The aspect ratio of the scaly shape is a value measured by the following method. A negative electrode mixture block was collected from the negative electrode subjected to the same pretreatment as "i. The collected negative electrode mixture block is cut to obtain a cut surface. The cut surface portion of the obtained negative electrode mixture was subjected to gold vapor deposition. Thereafter, the negative electrode mixture was placed in an electron microscope device, and the cut surface was observed. The observation conditions using an electron microscope are as follows. From the observed image, the maximum width and the maximum thickness were obtained for the scaly shape existing on the surface, and the aspect ratio was defined as the ratio of the maximum width to the maximum thickness (maximum width/maximum thickness).

Measurement machine: TOPCON scanning electron microscope SM-300

Acceleration voltage: 15kV

Multiplying power: 50 times, 100 times, 500 times, 1000 times, 2000 times (of these, the magnification at which the shape of the negative electrode mixture present on the surface is most clearly observed is adopted.)

The specific surface area of the negative electrode mixture of the negative electrode (A) for a lead-acid battery and the negative electrode (B) for a lead-acid battery is preferably 0.55m²/g～0.8m²(ii) in terms of/g. In this way, the charging efficiency can be further improved. The reason is presumably that, when the specific surface area of the negative electrode mixture is in the above range, lead sulfate generated in the gaps of the negative electrode mixture is more easily dissolved.

In the present specification, the specific surface area of the negative electrode mixture is a value (BET specific surface area) measured by the following method. A negative electrode mixture block was collected from the negative electrode subjected to the same pretreatment as "i. The collected negative electrode mixture (about 3.5g) was put into a measuring cell. After vacuum degassing treatment was performed at 100 ℃ for 1 hour, the measuring cell was attached to the apparatus, and measurement was performed under the following conditions.

Measurement machine: specific surface area/pore distribution measuring apparatus TriStar3000 manufactured by Shimadzu corporation

The measurement conditions were as follows: BET8 point method

Adsorbing gas: nitrogen gas

The specific surface areas of the negative electrode mixture of the negative electrode (A) for a lead-acid battery and the negative electrode (B) for a lead-acid battery are more preferably 0.6m²/g～0.75m²(ii) in terms of/g. In this way, the charging efficiency can be further improved.

A lead-acid battery according to an embodiment of the present invention is a lead-acid battery including the negative electrode (a) for a lead-acid battery or the negative electrode (B) for a lead-acid battery. The lead-acid battery has good charging efficiency because it includes the negative electrode (a) for a lead-acid battery or the negative electrode (B) for a lead-acid battery according to one embodiment of the present invention.

The lead storage battery is preferably used for an idling stop vehicle. The lead battery has high charging efficiency, and therefore, can be suitably used for an idling stop vehicle which requires efficient charging in a short time.

Hereinafter, a negative electrode for a lead-acid battery according to an embodiment of the present invention and a lead-acid battery will be described in detail in order.

Negative electrode (A) for lead-acid battery

A negative electrode plate as an example of the negative electrode (a) for a lead-acid battery according to an embodiment of the present invention includes a negative electrode current collector and a negative electrode mixture. The negative electrode mixture is held on the negative electrode current collector.

(negative current collector)

The negative electrode current collector is generally in the form of a grid plate. The negative electrode collector may be formed by casting lead (Pb) or a lead alloy, or may be formed by processing a lead or lead alloy sheet. Examples of the processing method include expanding (expanded) processing and punching (punching).

Examples of the lead alloy used for the negative electrode current collector include Pb-Sb alloys, Pb-Ca alloys, and Pb-Ca-Sn alloys. These lead or lead alloy may further contain elements such As Ba, Ag, Al, Bi, As, Se, Cu, etc. As additive elements. The negative electrode current collector may have lead alloy layers having different compositions, and the lead alloy layer may be plural.

(negative electrode mixture)

The negative electrode mixture contains lead.

Lead is a component that functions as a negative electrode active material, and is usually a main component in the negative electrode mixture. The content of lead in the negative electrode mixture may be, for example, 90 to 99.99 mass%. A part or all of the lead in the negative electrode mixture may be present as lead sulfate, lead oxide, or the like.

The negative electrode mixture may contain, in addition to lead, a carbonaceous material such as carbon black, and other additives such as barium sulfate and lignin, as necessary.

In an X-ray diffraction spectrum of the negative electrode mixture present on the surface of the negative electrode mixture, the ratio of the peak height at a diffraction angle of about 30.3 DEG to the peak height at a diffraction angle of about 31.2 DEG is 0.05 or more. The peak near the diffraction angle of 31.2 ° is a reference peak which appears strongly in normal lead. This means that when the peak height at a diffraction angle of about 30.3 ° is relatively large with respect to the peak height at a diffraction angle of about 31.2 °, lead is considered to be lead oxide and grow into a scale shape. The peak near diffraction angle 31.2 ° may be a peak appearing within 31.2 ° ± 0.3 ° or a peak appearing within 31.2 ° ± 0.1 °. The peak near diffraction angle 30.3 ° may be a peak appearing within 30.3 ° ± 0.3 °, or a peak appearing within 30.3 ° ± 0.1 °.

The lower limit of the peak height ratio is 0.05, preferably 0.1, and more preferably 0.15. By increasing the peak-to-height ratio, the charging efficiency can be improved better. On the other hand, the upper limit of the peak height ratio is, for example, 1, and may be 0.5, 0.4 or 0.3.

When the ratio of the peak height at a diffraction angle of 30.3 ° to the peak height at a diffraction angle of 31.2 ° in the X-ray diffraction spectrum of the negative electrode mixture present on the surface of the negative electrode mixture is 0.05 or more, at least a part of the negative electrode mixture present on the surface usually has a scaly shape. The components constituting the scaly shape are estimated to be components containing lead. The planar shape of the negative electrode mixture having a scaly shape is not particularly limited, and may be, for example, a sector shape, a semicircle shape, or the like. The lower limit of the aspect ratio of the scaly shape is preferably 3, and more preferably 5. On the other hand, the upper limit of the aspect ratio may be, for example, 10, or 8 or 7.

When the negative electrode mixture present on the surface is divided into a scaly shape and other shapes (spherical, massive, etc.), the number of scaly shapes is preferably 50% or more, more preferably 70% or more, and still more preferably 90% or more. The classification based on the shape difference of the negative electrode mixture can be performed based on an image obtained under an electron microscope under the condition of measuring the aspect ratio of the "scaly shape".

The lower limit of the specific surface area of the negative electrode mixture may be, for example, 0.4m²In g or 0.5m²A/g, preferably of 0.55m²A/g, more preferably 0.6m²(ii) in terms of/g. When the specific surface area of the negative electrode mixture is not less than the lower limit, the electrolyte solution sufficiently penetrates into the negative electrode mixture, and the like, so that lead sulfate is more easily eluted during charging, and the charging efficiency is more improved. The upper limit of the specific surface area of the negative electrode mixture may be, for example, 1m²A/g, preferably of 0.8m²A ratio of 0.75 m/g is more preferable²(ii) in terms of/g. When the specific surface area of the negative electrode mixture is not more than the upper limit, the charging efficiency is further improved by suppressing an electrolytic reaction of a generated gas or the like.

(method of manufacturing negative electrode)

The negative electrode plate is obtained by chemical conversion treatment of an unformed negative electrode plate. The unformed negative electrode plate is generally produced using lead powder containing lead monoxide as a main component, which is a raw material of the negative electrode active material. Specifically, the negative electrode current collector is filled with the negative electrode mixture paste, and the resultant mixture is aged and dried by a conventional method to produce an unformed negative electrode plate. The negative electrode mixture paste can be obtained by, for example, mixing carbon black, lignin, and barium sulfate as additives at a predetermined ratio in a lead powder containing lead monoxide as a main component, and then mixing water and 50% dilute sulfuric acid at a predetermined ratio. Aging and drying of the unformed negative plate are preferably performed at a temperature higher than room temperature and at a high humidity.

The obtained unformed negative electrode plate is subjected to chemical conversion treatment, whereby a negative electrode plate in which lead powder is spongy lead can be obtained. The formation may be performed by immersing the electrode plate group including the non-formed negative electrode plate in an electrolytic solution containing sulfuric acid in the lead storage battery cell and charging the electrode plate group. However, the formation may be performed before the lead-acid battery or the electrode plate group is assembled. By the formation, spongy lead can be produced and used as a negative electrode plate.

Here, the negative electrode mixture having the peak height ratio, that is, the negative electrode mixture in which at least a part of the negative electrode mixture present on the surface has a scaly shape can be obtained by adjusting the chemical conversion treatment conditions and adding an additive to the negative electrode mixture. Specifically, if carbon black having a small specific surface area, barium sulfate having a small average particle diameter and wood having a small molecular weight are used in combinationThe negative electrode mixture can be easily obtained by chemical conversion treatment under predetermined conditions. For example, the specific surface area of the carbon black to be used may be 70 to 240m²Preferably 100 to 200 m/g²(ii) in terms of/g. The average particle size of the barium sulfate used may be 0.1 to 0.5. mu.m, preferably 0.2 to 0.4. mu.m. The average molecular weight of the lignin used may be 1000 to 10000, preferably 3000 to 8000. The amount of carbon black added may be, for example, 0.1 to 1% by mass relative to the lead powder. The amount of barium sulfate added may be, for example, 1 to 5% by mass relative to the lead powder. The amount of lignin added may be, for example, 0.01 to 0.5 mass% based on the lead powder. The specific surface area of the negative electrode mixture can be adjusted by the particle size, specific surface area, and the like of each component used, the chemical conversion treatment conditions, and the like.

Negative electrode for lead-acid battery (B)

A negative electrode (B) for a lead-acid battery according to an embodiment of the present invention is the same as the negative electrode (a) for a lead-acid battery described above except that at least a part of the negative electrode mixture present on the surface has a scaly shape, the scaly shape has an aspect ratio of 3 to 10, and a ratio of a peak height at a diffraction angle of 30.3 ° to a peak height at a diffraction angle of 31.2 ° in an X-ray diffraction spectrum of the negative electrode mixture on the surface is not limited to 0.05 or more. Specific embodiments, preferable embodiments and manufacturing methods of the negative electrode (B) for a lead-acid battery may be the same as those of the negative electrode (a) for a lead-acid battery.

The lower limit of the aspect ratio of the scaly shape in the electrode (B) for a lead-acid battery is preferably 4, and more preferably 5. By setting the aspect ratio to the lower limit or more, the charging efficiency is further improved. On the other hand, the upper limit of the aspect ratio may be 10, or 8 or 7.

< lead storage battery >

A lead-acid battery according to an embodiment of the present invention includes a negative electrode plate as a negative electrode, a positive electrode plate as a positive electrode, and an electrolyte. A separator is disposed between the negative electrode plate and the positive electrode plate. The negative electrode plate, the positive electrode plate, and the separator are immersed in an electrolyte. The lead storage battery may be a liquid lead storage battery or a valve regulated lead storage battery, and preferably is a liquid lead storage battery.

(negative plate)

The negative electrode plate (a) for a lead-acid battery or the negative electrode plate (B) for a lead-acid battery according to one embodiment of the present invention is used.

(Positive plate)

The positive electrode plate can be classified into a paste type, a coating type, and the like.

The paste-type positive electrode plate generally includes a positive electrode collector in a lattice plate shape and a positive electrode mixture. The positive electrode mixture 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 may be formed by casting lead or a lead alloy, or by processing a lead or a lead alloy sheet.

The positive electrode plate includes a plurality of porous tubes, a core metal inserted into each tube, a positive electrode mixture filled in the tubes inserted into the core metal, and a connecting seat connecting the plurality of tubes.

The lead alloy used as the positive electrode current collector is preferably a Pb-Ca alloy, a Pb-Ca-Sn alloy, or the like, in view of corrosion resistance and mechanical strength. The positive electrode collector may have lead alloy layers having different compositions, and the lead alloy layer may be plural. The core metal is preferably a Pb-Sb alloy.

The positive electrode mixture contains a positive electrode active material (typically, lead dioxide or lead sulfate). The positive electrode mixture may contain additives such as tin sulfate and red lead, as needed, in addition to the positive electrode active material.

The unformed positive electrode plate of paste type is obtained by filling the positive electrode current collector with the obtained positive electrode mixture paste by a conventional method, aging and drying in the same manner as in the case of the negative electrode plate. The positive electrode material mixture paste is prepared by kneading lead powder, an additive, water, sulfuric acid, and the like. Thereafter, the unformed positive plate was formed. The positive electrode plate of the present invention is formed by filling a porous glass tube into which a core metal is inserted with lead powder or lead powder in a slurry form, and joining a plurality of tube connecting bases.

(electrolyte)

The electrolyte is an aqueous solution comprising sulfuric acid. The electrolyte may further contain metal ions such as sodium ions.

The electrolyte may be gelled as necessary. The degree of gelation is not particularly limited. An electrolyte solution in a gel state in a sol having fluidity may be used, or an electrolyte in a gel state having no fluidity may be used. The lower limit of the specific gravity of the electrolyte at 20 ℃ in the fully charged lead-acid battery is, for example, 1.1g/cm³Preferably 1.2g/cm³. On the other hand, the upper limit of the specific gravity is, for example, 1.4g/cm³Preferably 1.35g/cm³。

(spacer)

For the separator, a nonwoven fabric sheet, a microporous film, or the like can be used. The thickness and number of the separators interposed between the negative electrode plate and the positive electrode plate may be appropriately selected depending on the inter-electrode distance. The nonwoven fabric sheet is a sheet mainly composed of polymer fibers and glass fibers, and may be formed of a fiber component in an amount of 60 mass% or more, for example. On the other hand, the microporous membrane can be obtained, for example, by extrusion-molding a composition containing a polymer powder, a silica powder and an oil into a sheet shape, and then drawing out the oil to form pores. The material constituting the separator preferably has acid resistance, and the polymer component is preferably a polyolefin such as polyethylene or polypropylene.

(use)

The lead storage battery has good charging efficiency. Therefore, the lead-acid battery can be widely used for various applications in which a general lead-acid battery for automobiles and the like can be used. In particular, it is preferably used for an idling stop vehicle in which charge and discharge are repeated a plurality of times and excellent charge efficiency is required.

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 an electrode group 11, an electrolytic solution (not shown), and an electrolytic bath 12 for storing them. The inside of the electrolytic bath 12 is divided into a plurality of cell chambers 14 by partition walls 13. Each cell chamber 14 accommodates 1 electrode group 11. The opening of the electrolytic cell 12 is closed by a lid 15 provided with a negative electrode terminal 16 and a positive electrode terminal 17. In the lid 15, each cell chamber is provided with a liquid port plug 18. When replenishing water, the liquid port bolt 18 is removed and the replenishing liquid is replenished. The liquid port plug 18 may have a function of discharging gas generated in the cell chamber 14 to the outside of the battery.

Each of the electrode groups 11 is formed by stacking a plurality of negative electrode plates 2 and positive electrode plates 3 via separators 4. Here, the bag-shaped separator 4 that houses the negative electrode plate 2 is shown, but the form of the separator is not particularly limited. In the cell chamber 14 located at one end of the electrolytic bath 12, the negative electrode banks 6 of the plurality of negative electrode plates 2 connected in parallel are connected to the penetration connector 8, and the positive electrode banks 5 of the plurality of positive electrode plates 3 connected in parallel are connected to the positive electrode posts 7. The positive post 7 is connected to a positive terminal 17 outside the cover 15. In the cell chamber 14 located at the other end of the electrolytic bath 12, the negative electrode compartment 6 is connected to the negative electrode post 9, and the positive electrode compartment 5 is connected to the interconnector 8. The negative electrode tab 9 is connected to a negative electrode terminal 16 outside the cap 15. The through-connectors 8 are connected in series with the electrode plate groups 11 of the adjacent cell compartments 14 through-holes provided in the partition walls 13.

The present invention is not limited to the above embodiments, and various modifications and improvements can be made in addition to the above embodiments. For example, in the above-described embodiments, the positive electrode and the negative electrode are described as the positive electrode plate and the negative electrode plate, respectively, but the positive electrode and the negative electrode are not limited to the plate shape.

Examples

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

< example 1 >

(1) Production of unformed negative electrode plate

The specific surface area of the lead powder is 165m²0.3 mass% of carbon black, 2.1 mass% of barium sulfate having an average particle diameter of 0.3 μm, and 0.05 mass% of lignin having a mass average molecular weight of 6000. To this mixture, water and 50% diluted sulfuric acid were further added and kneaded to obtain a negative electrode mixture paste. The negative electrode mixture paste was filled into the mesh part of an expanded grid made of a Pb-Ca-Sn alloy, and aged and dried to obtain an unformed negative electrode plate.

(2) Production of unformed Positive plate

And mixing the lead oxide powder of the raw material with a sulfuric acid aqueous solution to obtain the positive electrode mixture paste. The positive electrode mixture paste was filled into the mesh part of an expanded grid made of a Pb-Ca-Sn alloy, and aged and dried to obtain an unformed positive electrode plate.

(3) Preparation of the electrolyte

Sulfuric acid was added to water to prepare an electrolyte.

(4) Production of lead-acid battery

The unformed negative electrode plate was housed in a bag-like separator made of a microporous film made of polyethylene, and an electrode group was formed with 7 sheets of the unformed negative electrode plate and 6 sheets of the unformed positive electrode plate. The electrode plate group and the electrolyte were placed in an electrolytic bath made of polypropylene, and the mixture was formed in the electrolytic bath, thereby assembling the liquid-type lead acid battery of example 1. The conversion was carried out with an electrical amount of 3.3Ah/g relative to the negative electrode mixture.

< example 2 >

A lead-acid battery of example 2 was assembled in the same manner as in example 1, except that the amount of lignin added was 0.07 mass%.

< example 3 >

As carbon black, a specific surface area of 140m was added²A lead-acid battery of example 3 was assembled in the same manner as in example 1, except that the amount of carbon black was 0.3 mass% and the amount of lignin added was 0.10 mass%.

< example 4 >

A lead-acid battery of example 4 was assembled in the same manner as in example 1, except that the amount of lignin added was changed to 0.10 mass%.

< example 5 >

As carbon black, 183m of specific surface area was added²A lead-acid battery of example 5 was assembled in the same manner as in example 1, except that the amount of carbon black was 0.3 mass% and the amount of lignin added was 0.10 mass%.

< example 6 >

As carbon black, a specific surface area of 140m was added²0.3 mass% of carbon black per gram, and 0.15 mass% of lignin,otherwise, the lead-acid battery of example 6 was assembled in the same manner as in example 1.

< example 7 >

A lead-acid battery of example 7 was assembled in the same manner as in example 1, except that the amount of lignin added was changed to 0.15 mass%.

< example 8 >

As carbon black, 183m of specific surface area was added²A lead-acid battery of example 8 was assembled in the same manner as in example 1, except that the amount of carbon black was 0.3 mass% and the amount of lignin added was 0.15 mass%.

< example 9 >

A lead-acid battery of example 9 was assembled in the same manner as in example 1, except that the amount of lignin added was changed to 0.20 mass%.

< example 10 >

A lead-acid battery of example 10 was assembled in the same manner as in example 1, except that the amount of lignin added was changed to 0.25 mass%.

< comparative example 1 >

As carbon black, a specific surface area of 214m was added²The lead storage battery of comparative example 1 was assembled in the same manner as in example 1 except that 0.5 mass% of carbon per gram, 2.1 mass% of barium sulfate having an average particle size of 0.6 μm was added as barium sulfate, and 0.05 mass% of lignin having an average molecular weight of 12000 was added as lignin.

< comparative example 2 >

A lead storage battery of comparative example 2 was assembled in the same manner as in comparative example 1, except that 0.07 mass% of lignin having an average molecular weight of 12000 was added as lignin.

< comparative example 3 >

A lead storage battery of comparative example 3 was assembled in the same manner as in comparative example 1, except that 0.10 mass% lignin having an average molecular weight of 12000 was added as lignin.

< comparative example 4 >

A lead storage battery of comparative example 4 was assembled in the same manner as in comparative example 1, except that 0.15 mass% of lignin having an average molecular weight of 12000 was added as lignin.

< comparative example 5 >

A lead storage battery of comparative example 5 was assembled in the same manner as in comparative example 1, except that 0.20 mass% of lignin having an average molecular weight of 12000 was added as lignin.

< comparative example 6 >

A lead storage battery of comparative example 6 was assembled in the same manner as in comparative example 1, except that 0.25 mass% of lignin having an average molecular weight of 12000 was added as lignin.

[ measurement ]

For the obtained negative electrode of each lead-acid battery, the specific surface area of the negative electrode mixture and the X-ray diffraction (XRD) spectrum of the surface were measured in the same manner as described above. The XRD spectrum of example 4 and the XRD spectrum of comparative example 5 are shown in fig. 2 and 3, respectively. The specific surface area and the ratio of the peak height at a diffraction angle (2 θ) of 30.3 ° to the peak height at a diffraction angle (2 θ) of 31.2 ° in the X-ray diffraction spectrum obtained are shown in table 1.

The shape of the surface of the negative electrode mixture was observed for each of the obtained negative electrodes of lead-acid batteries in the manner described above. The shape and aspect ratio based on the shape are shown in table 1. In the column of the shape in table 1, "generally" means a block or a sphere having a low aspect ratio.

Fig. 4 is an electron micrograph of the surface of the negative electrode mixture in the lead-acid battery of example 4. Fig. 5 is an electron micrograph of the surface of the negative electrode mixture in the lead-acid battery of comparative example 5. As is clear from fig. 4, in example 4, a plurality of scale-like protrusions (scale-like shapes) were formed on the surface. On the other hand, as is clear from fig. 5, in comparative example 5, such a scaly shape was not formed.

[ evaluation ]

< Idle Stop (IS) Life >

The idle stop life test was performed on each lead-acid battery in the following manner. In an atmosphere of 0 ℃, discharge was repeated for 30 cycles of 300A × 1.0 seconds, discharge was repeated for 25A × 25 seconds, and charge was repeated for 14.0V × 30 seconds, and minute current (20mA) discharge was performed for 6 hours each time. The minute current discharge is a dark current discharge at the time of the simulated engine stop. The above-described cycles, i.e., 30 cycles and the minute current discharge of 6h were repeated, and the time at which the discharge voltage at the 300A discharge became less than 7.2V was regarded as the lifetime. If the IS life IS long, it can be judged that the charging efficiency IS excellent.

The evaluation results are shown in table 1. The IS lifetime in table 1 IS shown as a relative value based on comparative example 1 (100%).

[ Table 1]

As shown in table 1, the lead-acid batteries of examples 1 to 10 all had an IS life of 130% or more and good charging efficiency. Further, if the embodiments are compared with each other, it is known that: the specific surface area of the negative electrode mixture was 0.55m²/g～0.8m²In the case of/g, the IS lifetime IS longer when the peak height ratio in the X-ray diffraction spectrum IS higher. On the other hand, the lead-acid batteries of comparative examples 1 to 6, in which the shape of the surface of the negative electrode mixture was not scaly and the peak height ratio in the X-ray diffraction spectrum was low, all had short IS life and insufficient charging efficiency.

Industrial applicability

The lead acid battery of the present invention can be used as a power source for automobiles, motorcycles, electric vehicles (e.g., forklift trucks), industrial power storage devices, and the like, and is particularly preferably used as a power source for idle stop vehicles.

Description of the reference numerals

1 lead accumulator

2 negative plate

3 Positive plate

4 spacer

5 positive pole shed

6 negative electrode shed

7 positive pole

8-pass-through connector

9 negative pole column

11 polar plate group

12 electrolytic cell

13 bulkhead

14 single cell chamber

15 cover

16 negative terminal

17 positive terminal

18 liquid mouth bolt

Claims (6)

1. A negative electrode for a lead-acid battery, comprising a negative electrode mixture containing lead,

in the X-ray diffraction spectrum of the negative electrode mixture present on the surface, the ratio of the peak height at a diffraction angle of about 30.3 DEG to the peak height at a diffraction angle of about 31.2 DEG is 0.05 or more.

2. A negative electrode for a lead-acid battery, comprising a negative electrode mixture containing lead,

at least a part of the negative electrode mixture present on the surface has a scaly shape, and the aspect ratio of the scaly shape is 3 to 10.

3. The negative electrode for a lead-acid battery according to claim 1 or 2, wherein the specific surface area of the negative electrode mixture is 0.55m²/g～0.8m²/g。

4. The negative electrode for a lead-acid battery according to claim 3, wherein the specific surface area of the negative electrode mixture is 0.6m²/g～0.75m²/g。

5. A lead-acid battery comprising the negative electrode for a lead-acid battery as defined in any one of claims 1 to 4.

6. The lead-acid battery as claimed in claim 5, which is used for an idling stop vehicle.