JP7010556B2 - Positive electrode plate and lead acid battery - Google Patents

Description

The present invention relates to a positive electrode plate and a lead storage battery.

Lead-acid batteries are widely used in industry and are used, for example, in automobile batteries, backup power sources, and main power sources for electric vehicles. In recent years, for the purpose of measures against carbon dioxide emission regulations, fuel efficiency, etc., an idling stop system vehicle (hereinafter referred to as "ISS vehicle") equipped with a system that stops the engine when controlling power generation, waiting for a signal, etc. has been actively studied. Lead-acid batteries are also required to have characteristics suitable for ISS vehicle applications.

For example, in an ISS vehicle, a lead-acid battery is used in a partially charged state called PSOC (Partial State Of Charge). When a lead-acid battery is used under PSOC, the life of the lead-acid battery tends to be shorter than when it is used in a fully charged state. Therefore, lead-acid batteries for ISS vehicles are required to be able to suppress deterioration of characteristics such as life (excellent in cycle performance) even when repeatedly used under PSOC.

On the other hand, for example, in Patent Document 1, a lead storage battery including a positive electrode plate having an active material specific surface area of 6 m ² / g or more and a negative electrode plate to which a predetermined material is added is used under PSOC. It is disclosed that the life (cycle performance) can be improved.

International Publication No. 2011/108056

However, there is still room for improvement in the cycle performance of lead-acid batteries. Therefore, an object of the present invention is to provide a lead storage battery having excellent cycle performance and a positive electrode plate for the lead storage battery.

One aspect of the present invention is a positive electrode plate for a lead storage battery, comprising a positive electrode current collector and a positive electrode active material held by the positive electrode current collector, and the positive electrode active material contains carbon fibers having a layered structure.

The carbon fiber may be a carbon nanotube. The specific surface area of the positive electrode active material may be 7.0 m ² / g or more. The positive electrode active material may contain PbO ₂ , and the ratio of the peak intensities of the X-ray diffraction patterns of α-PbO ₂ and β-PbO ₂ in the positive electrode active material (α-PbO ₂ / β-PbO ₂ ) is 0. It may be 60 or less.

Another aspect of the present invention is a lead-acid battery provided with the above-mentioned positive electrode plate.

According to the present invention, it is possible to provide a lead storage battery having excellent cycle performance and a positive electrode plate for the lead storage battery.

It is a perspective view which shows the whole structure and the internal structure of the lead storage battery which concerns on one Embodiment. It is a perspective view which shows the electrode group of the lead storage battery shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail.

FIG. 1 is a perspective view showing the overall configuration and internal structure of the lead storage battery according to the embodiment. As shown in FIG. 1, the lead-acid battery 1 includes an electric tank 2 having an open upper surface and a lid 3 for closing the opening of the electric tank 2. The battery case 2 and the lid 3 are made of polypropylene, for example. The lid 3 is provided with a negative electrode terminal 4, a positive electrode terminal 5, and a liquid port plug 6 for closing the liquid injection port provided in the lid 3.

Inside the battery case 2, an electrode group 7, a negative electrode column 8 connecting the electrode group 7 to the negative electrode terminal 4, a positive electrode column (not shown) connecting the electrode group 7 to the positive electrode terminal 5, dilute sulfuric acid, etc. Electrolyte and is stored.

FIG. 2 is a perspective view showing the electrode group 7. As shown in FIG. 2, the electrode group 7 includes a negative electrode plate 9, a positive electrode plate 10, and a separator 11 arranged between the negative electrode plate 9 and the positive electrode plate 10. The negative electrode plate 9 includes a negative electrode current collector (negative electrode grid) 12 and a negative electrode active material 13 held by the negative electrode current collector 12. The positive electrode plate 10 includes a positive electrode current collector (positive electrode lattice body) 14 and a positive electrode active material 15 held by the positive electrode current collector 14. In the present specification, the negative electrode plate after chemical conversion from which the negative electrode current collector is removed is referred to as “negative electrode active material”, and the positive electrode plate after chemical conversion from which the positive electrode current collector is removed is referred to as “positive electrode active material”. Define.

The electrode group 7 has a structure in which a plurality of negative electrode plates 9 and positive electrode plates 10 are alternately laminated in a direction substantially parallel to the opening surface of the electric tank 2 via a separator 11. That is, the negative electrode plate 9 and the positive electrode plate 10 are arranged so that their main surfaces extend in the direction perpendicular to the opening surface of the battery case 2. In the electrode group 7, the selvage portions 12a of the negative electrode current collectors 12 in the plurality of negative electrode plates 9 are collectively welded by the negative electrode side strap 16. Similarly, the selvage portions 14a of each of the positive electrode current collectors 14 in the plurality of positive electrode plates 10 are collectively welded by the positive electrode side strap 17. The negative electrode side strap 16 and the positive electrode side strap 17 are connected to the negative electrode terminal 4 and the positive electrode terminal 5 via the negative electrode column 8 and the positive electrode column, respectively.

The separator 11 is formed in a bag shape, for example, and houses the negative electrode plate 9. The separator 11 is made of, for example, polyethylene (PE), polypropylene (PP), or the like. The separator 11 may be made by adhering inorganic particles such as SiO ₂ and Al ₂ O ₃ to a woven fabric, a non-woven fabric, a porous membrane or the like formed of these materials.

The negative electrode current collector 12 and the positive electrode current collector 14 are each made of a lead alloy. The lead alloy may be an alloy containing tin, calcium, antimony, selenium, silver, bismuth and the like in addition to lead, and specifically, for example, an alloy containing lead, tin and calcium (Pb-Sn). -Ca-based alloy) may be used.

The negative electrode active material 13 contains at least Pb as a Pb component, and further contains a Pb component other than Pb (for example, PbSO ₄ ) and an additive, if necessary. The negative electrode active material 13 preferably contains a porous spongy lead.

Additives include, for example, resins having sulfo groups and / or sulfonic acid bases, barium sulfate, carbon materials (excluding carbon fibers) and short reinforcing fibers (acrylic fibers, polyethylene fibers, polypropylene fibers, polyethylene terephthalate fibers, carbon). Fiber, etc.).

Resins having a sulfo group and / or a sulfonic acid base include lignin sulfonic acid, lignin sulfonate, and a condensate of phenols, aminoaryl sulfonic acid, and formaldehyde (for example, bisphenol, aminobenzene sulfonic acid, and formaldehyde). It may be at least one selected from the group consisting of condensates). Examples of the carbon material include carbon black and graphite. Examples of carbon black include furnace black, channel black, acetylene black, thermal black and ketjen black.

The negative electrode active material 13 can be obtained by aging and drying the negative electrode active material paste held in the negative electrode current collector 12 to obtain an unchemicald negative electrode active material, and then forming an unchemicald negative electrode active material. Can be done. The negative electrode active material paste contains, for example, lead powder, additives, solvent (eg water or organic solvent) and sulfuric acid (eg dilute sulfuric acid). The negative electrode active material paste is obtained, for example, by mixing a lead powder and an additive to obtain a mixture, and then adding a solvent and sulfuric acid to the mixture and kneading the mixture.

The lead powder is, for example, lead powder produced by a ball mill type lead powder manufacturing machine or a barton pot type lead powder manufacturing machine (in a ball mill type lead powder manufacturing machine, a mixture of powder of the main component PbO and scaly metal lead). ).

The aging may be carried out in an atmosphere having a temperature of 35 to 85 ° C. and a humidity of 50 to 98 RH% for 15 to 60 hours. Drying may be carried out at a temperature of 45 to 80 ° C. for 15 to 30 hours.

In one embodiment, the positive electrode active material 15 contains PbO ₂ , which is a Pb component, and carbon fibers having a layered structure. The positive electrode active material 15 may further contain a Pb component (for example, PbSO ₄ ) other than PbO ₂ and an additive, if necessary.

The content of the Pb component is preferably 90% by mass or more, more preferably 95% by mass or more, based on the total mass of the positive electrode active material, from the viewpoint of further improving the low temperature and high rate discharge performance and the cycle performance. The content of the Pb component is preferably 99.9% by mass or less, more preferably 98% by mass or less, based on the total mass of the positive electrode active material from the viewpoint of reducing the manufacturing cost and weight. From these viewpoints, the content of the Pb component is 90 to 99.9% by mass, 95 to 99.9% by mass, 90 to 98% by mass or 95 to 98% by mass based on the total mass of the positive electrode active material. It may be there.

The positive electrode active material 15 preferably contains β-PbO ₂ as a Pb component. The positive electrode active material 15 may further contain α-PbO ₂ as a Pb component. That is, the positive electrode active material 15 may contain only β-PbO ₂ as a Pb component in one embodiment, and may contain α-PbO ₂ and β-PbO ₂ as Pb components in another embodiment. good.

The ratio of the peak intensity of the X-ray diffraction pattern of α-PbO ₂ and β-PbO ₂ in the positive electrode active material 15 (α-PbO ₂ / β-PbO ₂ ) is from the viewpoint of excellent charge acceptance performance and low-temperature high-rate discharge performance. It is preferably 0.60 or less, more preferably 0.50 or less, still more preferably 0.40 or less, and particularly preferably 0.30 or less. The ratio α-PbO ₂ / β-PbO ₂ is preferably 0.01 or more, more preferably 0.10 or more, still more preferably 0.25 or more, from the viewpoint of further excellent cycle performance. From these viewpoints, the ratio α-PbO ₂ / β-PbO ₂ is 0.01 to 0.60, 0.01 to 0.50, 0.01 to 0.40, 0.01 to 0.30, 0. .10 to 0.60, 0.10 to 0.50, 0.10 to 0.40, 0.10 to 0.30, 0.25 to 0.60, 0.25 to 0.50, 0.25 It may be ~ 0.40 or 0.25 ~ 0.30.

The ratio α-PbO ₂ / β-PbO ₂ is the ratio in the positive electrode active material 15 after chemical conversion (fully charged state). The ratio α-PbO ₂ / β-PbO ₂ can be adjusted, for example, by adjusting the amount of dilute sulfuric acid used in the production of the positive electrode active material 15, the temperature at the time of chemical conversion, and the like. For example, the larger the amount of dilute sulfuric acid used in the production of the positive electrode active material 15, the lower the ratio α-PbO ₂ / β-PbO ₂ , and the higher the chemical conversion temperature, the higher the ratio α-PbO ₂ / β-PbO ₂ . Become.

The ratio α-PbO ₂ / β-PbO ₂ is calculated by wide-angle X-ray diffraction measurement of the positive electrode active material 15. In the wide-angle X-ray diffraction measurement of the positive electrode active material 15, for example, peaks derived from α-PbO ₂ , β-PbO ₂ and PbSO ₄ are detected as the main compounds. Using the main peak intensity (cps) specified as α-PbO ₂ and β-PbO ₂ , the ratio of "main peak intensity of α-PbO ₂ " / "main peak intensity of β-PbO ₂ " Calculated as α-PbO ₂ / β-PbO ₂ .

Wide-angle X-ray diffraction measurement is performed by, for example, the following method.
-Measuring device: Fully automatic multipurpose horizontal X-ray diffractometer SmartLab (manufactured by Rigaku Co., Ltd.)
・ X-ray source: Cu-Kα / 1.541862Å
-Filter: Cu-Kβ
・ Output: 40kV, 30mA
-Scan mode: CONTINUOUS
・ Scan range: 20.0000 degrees to 60.000 degrees ・ Step width: 0.0200 degrees ・ Scan axis: 2θ / θ
・ Scan speed: 10.000 degrees / min ・ Sample holder: Made of glass, depth 0.2 mm
-Sample preparation method: The measurement sample can be prepared by the following procedure. First, the formed battery is disassembled, the positive electrode plate is taken out, washed with water, and then dried at 50 ° C. for 24 hours. Next, 3 g of the positive electrode active material is collected from the central portion of the positive electrode plate and ground.
-Calculation method: Fill the sample holder with the positive electrode active material so that the thickness of the positive electrode active material is equal to the depth of the sample holder, and prepare a smooth sample surface. Wide-angle X-ray diffraction is measured, and an X-ray diffraction pattern (X-ray diffraction chart) of the diffraction angle (2θ) and the diffraction peak intensity is obtained. In the X-ray diffraction pattern, for example, α-PbO ₂ located at a diffraction angle of 28.6 degrees and β-PbO ₂ located at a diffraction angle of 25.3 degrees are detected. "Peak intensity of α-PbO ₂ " / "Peak intensity of β-PbO ₂ " using the peak intensities (cps) specified as α-PbO ₂ (110 planes) and β-PbO ₂ (111 planes) respectively. Is calculated as the ratio α-PbO ₂ / β-PbO ₂ .

The carbon fiber having a layered structure is a fibrous (elongated shape) carbon material. In the present specification, "carbon fiber" (fibrous (elongated shape) carbon material) in "carbon fiber having a layered structure" is defined as a carbon material having an aspect ratio of 100 or more. The aspect ratio is the ratio (maximum length /) of the maximum length of the carbon material to the minimum length of the carbon material in the direction perpendicular to the direction having the maximum length, which is calculated from the scanning electron micrograph of the carbon material. Minimum length).

The carbon fiber having a layered structure has one or more layers composed of a plurality of carbon atoms as the layered structure, for example, when the cross section perpendicular to the longitudinal direction of the carbon fiber is viewed. The carbon fiber having a layered structure has, for example, one or two or more tubular layers composed of a plurality of carbon atoms. The carbon fiber having a layered structure is preferably a carbon fiber having a multi-layer structure having two or more layers from the viewpoint of further excellent oxidation resistance. The carbon fiber having a layered structure may be in the shape of a hollow cylinder having a hollow portion penetrating in the longitudinal direction. It can be confirmed that the carbon fibers have a layered structure, for example, by obtaining the lamination (lattice surface) spacing from the diffraction profile by powder X-ray diffraction method. The carbon fiber having a layered structure is not particularly limited, but may be, for example, a carbon nanotube.

In the lead storage battery 1, excellent cycle performance can be obtained because the positive electrode active material 15 contains carbon fibers having such a layered structure. The reason is that since the carbon material is fibrous, the Pb components (PbO ₂ , PbSO ₄ , etc.) in the positive electrode active material 15 are connected to each other to suppress the muddy formation of the positive electrode active material 15 and have a layered structure. The present inventors presume that this is to improve the oxidation resistance of the positive electrode active material 15.

The content of the carbon fiber having a layered structure is based on the total mass of the positive electrode active material from the viewpoint of more preferably imparting electrical conductivity and better binding Pb components (PbO ₂ , PbSO ₄ , etc.) to each other. It is preferably 0.02% by mass or more, more preferably 0.1% by mass or more, and further preferably 1.5% by mass or more. The content of the carbon fiber having a layered structure is preferably 3.0% by mass or less, more preferably 1.0% by mass, based on the total mass of the positive electrode active material from the viewpoint of suppressing the amount of reduction of the electrolytic solution. Hereinafter, it is more preferably 0.5% by mass or less.

Examples of the additive include carbon materials (excluding carbon fibers having a layered structure) and short reinforcing fibers (acrylic fibers, polyethylene fibers, polypropylene fibers, polyethylene terephthalate fibers, etc. Excluding carbon fibers having a layered structure). Can be mentioned. Examples of the carbon material include carbon black and graphite. Examples of carbon black include furnace black, channel black, acetylene black, thermal black and ketjen black.

The specific surface area of the positive electrode active material 15 as described above is preferably 7.0 m ² / g or more, more preferably 9.0 m ² / g or more, still more preferably, from the viewpoint of excellent charge acceptance performance and low temperature high rate discharge performance. Is 12.0 m ² / g or more. The specific surface area of the positive electrode active material 15 is preferably 20.0 m ² / g or less, more preferably 15.0 m ² / g or less, and more preferably 10.0 m ² / g or less from the viewpoint of further excellent cycle performance. .. From these viewpoints, the specific surface areas of the positive electrode active material 15 are 7.0 to 20.0 m ² / g, 7.0 to 15.0 m ² / g, 7.0 to 10.0 m ² / g, 9.0. ~ 20.0m ² / g, 9.0 ~ 15.0m ² / g, 9.0 ~ 10.0m ^{2 / g, 12.0 ~ 20.0m 2 /} g, or 12.0-15.0m ² It may be / g.

The specific surface area of the positive electrode active material is the specific surface area of the positive electrode active material after chemical conversion (fully charged state), and is measured by the BET method. The BET method is a method in which an inert gas (for example, nitrogen gas) having a known molecular size is adsorbed on the surface of a measurement sample, and the surface area is obtained from the adsorbed amount and the occupied area of the inert gas. This is a general method for measuring surface area. The specific surface area of the positive electrode active material is, for example, a method of adjusting the amount of sulfuric acid and water added when producing a positive electrode active material paste, which will be described later, a method of refining the active material at the unchemical stage, and changing the chemical conditions. It can be adjusted by a method or the like.

The positive electrode active material 15 is obtained by aging and drying the positive electrode active material paste held in the positive electrode current collector 14 under the same conditions as at the time of producing the negative electrode active material to obtain an unchemicald positive electrode active material, and then unchemicalized. It can be obtained by forming the positive electrode active material of. The positive electrode active material paste may be, for example, lead powder similar to that used for the negative electrode active material paste, carbon fibers having a layered structure, additives added as necessary, a solvent (for example, water or an organic solvent) and sulfuric acid (for example, water or organic solvent). For example, dilute sulfuric acid) is contained. The positive electrode active material paste may further contain lead tan (Pb ₃ O ₄ ) from the viewpoint of shortening the chemical formation time.

The lead-acid battery 1 described above is manufactured by, for example, a manufacturing method including an electrode plate manufacturing process for obtaining an electrode plate (negative electrode plate and a positive electrode plate) and an assembly step for assembling components including the electrode plate to obtain a lead-acid battery 1. Will be done.

In the electrode plate manufacturing process, for example, the negative electrode current collector 12 holds the negative electrode active material paste, and then the negative electrode plate 9 is obtained by aging and drying under the above-mentioned conditions, and the positive electrode current collector 14 is formed. After retaining the positive electrode active material paste, the unchemicald positive electrode plate 10 is obtained by aging and drying under the above-mentioned conditions.

In the assembly step, for example, the obtained negative electrode plates and positive electrode plates are laminated via the separator 11 and the current collecting portions of the electrode plates having the same polarity are welded with a strap to obtain an electrode group. This group of electrodes is arranged in an electric tank to manufacture an unchemical lead-acid battery. Next, dilute sulfuric acid is put into a non-chemical lead-acid battery, and a direct current is applied to form an electric tank. Subsequently, the lead storage battery 1 can be obtained by adjusting the specific gravity (20 ° C.) of the sulfuric acid after chemical conversion to an appropriate specific density of the electrolytic solution. The specific gravity (20 ° C.) of sulfuric acid used for chemical formation may be 1.15 to 1.25. The specific gravity (20 ° C.) of sulfuric acid after chemical conversion is preferably 1.25 to 1.33, more preferably 1.26 to 1.30. The chemical conversion conditions and the specific density of sulfuric acid can be adjusted according to the size of the electrode plate. The chemical conversion treatment may be carried out in the assembly process or in the electrode plate manufacturing process (tank chemical conversion).

Hereinafter, the present invention will be specifically described with reference to Examples. However, the present invention is not limited to the following examples.

<Example 1>
(Manufacturing of positive electrode plate)
To 100 parts by mass of lead powder, 0.2 parts by mass of carbon nanotubes (multi-walled carbon fiber, manufactured by Sigma-Aldrich, trade name: SWeNTSMW 200) were added and dry-mixed. Next, 3 parts by mass of water was added to 100 parts by mass of the mixture composed of lead powder and carbon nanotubes, and 9 parts by mass of dilute sulfuric acid (specific gravity 1.28) was added stepwise and kneaded for 1 hour to activate the positive electrode. A material paste was made. An expanded positive electrode current collector produced by expanding a rolled sheet made of a lead alloy was filled with a positive electrode active material paste and then aged in an atmosphere of a temperature of 50 ° C. and a humidity of 98% for 24 hours. Then, it dried at a temperature of 50 degreeC for 16 hours to obtain an unchemical positive electrode plate.

(Manufacturing of negative electrode plate)
Vispers P215 (condensed product of bisphenol, aminobenzenesulfonic acid and formaldehyde, trade name, manufactured by Nippon Paper Co., Ltd.) 0.2 parts by mass (resin solid content), 0.1 part by mass of acrylic fiber with respect to 100 parts by mass of lead powder. A mixture of parts by mass, 1.0 part by mass of barium sulfate, and 0.2 parts by mass of furnace black was added and mixed dry. Next, water was added to this mixture and kneaded, and then the mixture was further kneaded while adding dilute sulfuric acid having a specific gravity of 1.280 little by little to prepare a negative electrode active material paste. An expanded negative electrode current collector produced by expanding a rolled sheet made of a lead alloy was filled with this negative electrode active material paste and then aged in an atmosphere of a temperature of 50 ° C. and a humidity of 98% for 24 hours. Then, it dried at a temperature of 50 degreeC for 16 hours to obtain an unchemical negative electrode plate.

(Assembly of lead-acid battery)
An unchemical negative electrode plate was inserted into a polyethylene separator processed into a bag shape. Next, seven unchemical positive electrode plates and eight unchemical negative electrode plates inserted into the bag-shaped separator were alternately laminated. Subsequently, the ears of the electrode plates having the same polarity were welded to each other by a cast-on-strap (COS) method to prepare an electrode group. The electrode group was inserted into the battery case to assemble a 2V single cell battery (corresponding to a D23 size single cell specified in JIS D 5301). Then, sulfuric acid having a specific density of 1.240 was injected, and the mixture was placed in a water tank at 40 ° C. and allowed to stand for 1 hour. Then, chemical conversion was carried out at 17 A with a constant current for 18 hours. The specific gravity of the electrolytic solution (sulfuric acid solution) after chemical conversion was adjusted to 1.29 (20 ° C.).

(Measurement of ratio α-PbO ₂ / β-PbO ₂ based on peak intensity of X-ray diffraction pattern)
The measurement sample was prepared by the following procedure. First, the battery formed by the above procedure was disassembled, and one electrode group was taken out. Next, all the positive electrode plates were taken out from the taken-out electrode group, washed with water, and then dried at 50 ° C. for 24 hours. Next, 3 g of the positive electrode active material was collected from the central portion of the positive electrode plate and ground. Subsequently, the sample holder is filled with the positive electrode active material so that the thickness of the positive electrode active material is equal to the depth of the sample holder to prepare a smooth sample surface, and then the ratio α-PbO ₂ / β-PbO ₂ is measured. Was done. The ratio α-PbO ₂ / β-PbO ₂ was taken as the average value of the ratio α-PbO ₂ / β-PbO ₂ calculated for all the positive electrode plates taken out from the electrode group. The measurement conditions for the ratio α-PbO ₂ / β-PbO ₂ are shown below.

[Measurement conditions for ratio α-PbO ₂ / β-PbO ₂ ]
-Measuring device: Fully automatic multipurpose horizontal X-ray diffractometer SmartLab (manufactured by Rigaku Co., Ltd.)
・ X-ray source: Cu-Kα / 1.541862Å
-Filter: Cu-Kβ
・ Output: 40kV, 30mA
-Scan mode: CONTINUOUS
・ Scan range: 20.0000 degrees to 60.000 degrees ・ Step width: 0.0200 degrees ・ Scan axis: 2θ / θ
・ Scan speed: 10.000 degrees / min ・ Sample holder: Made of glass, depth 0.2 mm
-Calculation method: As a result of measuring wide-angle X-ray diffraction using 3 g of the prepared sample (positive electrode active material), the diffraction angle is 28.6 degrees from the X-ray diffraction chart of the diffraction angle (2θ) and the diffraction peak intensity obtained. Α-PbO ₂ located at and β-PbO ₂ located at a diffraction angle of 25.3 degrees were detected. "Peak intensity of α-PbO ₂ " / "β-PbO ₂ " using the peak intensity (cps) of the waveform specified as a compound of α-PbO ₂ (110 planes) and β-PbO ₂ (111 planes) respectively. The ratio of "peak intensity of" was calculated as the ratio α-PbO ₂ / β-PbO ₂ .

(Measurement of specific surface area of positive electrode active material)
A sample for measuring the specific surface area was prepared by the following procedure. First, the battery formed by the above procedure was disassembled, and one electrode group was taken out. Next, all the positive electrode plates were taken out from the taken-out electrode group, washed with water, and then dried at 50 ° C. for 24 hours. Next, 2 g of the positive electrode active material was collected from the central portion of the positive electrode plate and dried at 130 ° C. for 30 minutes to prepare a measurement sample.

While cooling the measurement sample prepared as described above with liquid nitrogen, the amount of nitrogen gas adsorbed was measured by a multi-point method at the liquid nitrogen temperature, and the specific surface area of the positive electrode active material was calculated according to the BET method. The specific surface area of the positive electrode active material was the average value of the specific surface areas of the positive electrode active material calculated for all the positive electrode plates taken out from the electrode group. The measurement conditions are shown below.

[Measurement conditions for specific surface area]
-Device: Macsorb1201 (manufactured by Mountech Co., Ltd.)
・ Degassing time: 10 minutes at 130 ° C ・ Cooling: 5 minutes with liquid nitrogen ・ Adsorbed gas flow rate: 25 mL / min

<Comparative Example 1>
A lead-acid battery was prepared and each measurement was carried out in the same manner as in Example 1 except that carbon nanotubes were not used when preparing the positive electrode active material paste.

<Example 2>
The same as in Example 1 except that the dilute sulfuric acid used for producing the positive electrode active material paste was changed to 11 parts by mass of dilute sulfuric acid (specific gravity 1.28) and the specific gravity of the sulfuric acid injected at the time of chemical conversion was changed to 1.235. , A lead-acid battery was prepared and each measurement was performed.

<Comparative Example 2>
A lead-acid battery was prepared and each measurement was carried out in the same manner as in Example 2 except that carbon nanotubes were not used when preparing the positive electrode active material paste.

<Example 3>
Except for changing the blending amount of water to 12 parts by mass, the dilute sulfuric acid to be used to 15 parts by mass of dilute sulfuric acid (specific gravity 1.28), and the specific gravity of sulfuric acid to be injected at the time of chemical conversion to 1.230 when preparing the positive electrode active material paste. Made a lead-acid battery and measured each of them in the same manner as in Example 1.

<Comparative Example 3>
A lead-acid battery was prepared and each measurement was carried out in the same manner as in Example 3 except that carbon nanotubes were not used when preparing the positive electrode active material paste.

<Example 4>
A lead-acid battery was prepared and each measurement was carried out in the same manner as in Example 3 except that the specific gravity of the sulfuric acid to be injected at the time of chemical conversion was changed to 1.200 and the standing time after the injection of sulfuric acid was changed to 5 hours.

<Comparative Example 4>
A lead-acid battery was prepared and each measurement was carried out in the same manner as in Example 4 except that carbon nanotubes were not used when preparing the positive electrode active material paste.

<Example 5>
Except for changing the blending amount of water to 9 parts by mass, the dilute sulfuric acid to be used to 25 parts by mass of dilute sulfuric acid (specific gravity 1.34), and the specific gravity of sulfuric acid to be injected during chemical conversion to 1.200 when preparing the positive electrode active material paste. Made a lead-acid battery and measured each of them in the same manner as in Example 1.

<Comparative Example 5>
A lead-acid battery was prepared and each measurement was carried out in the same manner as in Example 5 except that carbon nanotubes were not used when preparing the positive electrode active material paste.

<Example 6>
A lead-acid battery was prepared and each measurement was carried out in the same manner as in Example 3 except that the standing time after the injection of sulfuric acid was changed to 5 hours.

<Example 7>
A lead-acid battery was prepared and each measurement was carried out in the same manner as in Example 5 except that the water tank temperature at the time of chemical conversion was changed to 45 ° C.

<Example 8>
Except for changing the blending amount of water to 11 parts by mass, the dilute sulfuric acid to be used to 23 parts by mass of dilute sulfuric acid (specific gravity 1.55), and the specific gravity of sulfuric acid to be injected during chemical conversion to 1.185 when preparing the positive electrode active material paste. Made a lead-acid battery and measured each of them in the same manner as in Example 1.

<Example 9>
Except for changing the amount of water to be added to 3 parts by mass, the dilute sulfuric acid to be used to 30 parts by mass of dilute sulfuric acid (specific gravity 1.55), and the specific gravity of sulfuric acid to be injected during chemical conversion to 1.170 when preparing the positive electrode active material paste. Made a lead-acid battery and measured each of them in the same manner as in Example 1.

The performance of the lead-acid batteries of each Example and Comparative Example was evaluated as follows.
(Charge acceptance performance)
The produced lead storage battery was left for about 12 hours after chemical conversion, then subjected to constant current discharge at 25 ° C. at a current value of 10.4 A for 30 minutes, and after being left for 6 hours, a current limit of 100 A at 2.33 V. The constant voltage charge is performed for 60 seconds, the current value from the start to the 5th second is measured, and the current value per unit mass of the positive electrode active material (“current value” / “content of positive electrode active material (g)). ") Was calculated. The measurement result of Comparative Example 1 (current value per unit mass of the positive electrode active material) was set as 100 for relative evaluation.

(Low temperature and high rate discharge performance)
After adjusting the battery temperature of the manufactured lead-acid battery to -15 ° C, constant current discharge is performed at 300 A, the discharge duration until the cell voltage falls below 1.0 V is measured, and the discharge per unit mass of the positive electrode active material is performed. The duration (“discharge duration” / “content of positive electrode active material (g)”) was calculated. The low temperature and high rate discharge performance was relatively evaluated with the measurement result of Comparative Example 1 (discharge duration per unit mass of the positive electrode active material) as 100.

(Cycle performance)
For the produced lead-acid battery, the ambient temperature was adjusted so that the battery temperature became 25 ° C., and after performing constant current discharge for 45A-59 seconds and constant current discharge for 300A-1 second, the current limit current was 100A-2.33V-. A test was conducted in which the operation of performing constant current / constant voltage charging for 60 seconds was one cycle. This test is a cycle test that simulates how lead-acid batteries are used in ISS vehicles. In this cycle test, since the charge amount is small with respect to the discharge amount, if the charge is not completely performed, the charge gradually becomes insufficient, and as a result, the voltage at the first second when the discharge current is set to 300 A and the discharge is performed for 1 second. It gradually decreases. That is, if the negative electrode is polarized during constant current / constant voltage charging and switches to constant voltage charging at an early stage, the charging current is attenuated and charging becomes insufficient. In this cycle test, the voltage at the first second when discharged at 300 A is measured, the number of cycles when the voltage drops below 1.2 V is determined, and the number of cycles per unit mass of the positive electrode active material (“when the voltage drops below 1.2 V”). The number of cycles ”/“ content of positive electrode active material (g) ”) was determined. The cycle performance was relatively evaluated with the measurement result of Comparative Example 1 (the number of cycles per unit mass of the positive electrode active material) as 100.

Table 1 shows the characteristics of the positive electrode active material and the performance of the lead storage battery in each Example and Comparative Example.

1 ... Lead-acid battery, 9 ... Negative electrode plate, 10 ... Positive electrode plate, 11 ... Separator, 12 ... Negative electrode current collector, 13 ... Negative electrode active material, 14 ... Positive electrode current collector, 15 ... Positive electrode active material.

Claims (5)

A positive electrode current collector and a positive electrode active material held by the positive electrode current collector are provided.
The positive electrode active material contains carbon fibers having a layered structure and contains carbon fibers.
A positive electrode plate for a lead storage battery, wherein the specific surface area of the positive electrode active material is 7.0 m ² / g or more and 10.3 m ² / g or less . The positive electrode plate according to claim 1, wherein the carbon fibers are carbon nanotubes. The positive electrode active material contains PbO ₂ and contains
The invention according to claim 1 or 2 , wherein the ratio of the peak intensities of the X-ray diffraction patterns of α-PbO ₂ and β-PbO ₂ (α-PbO ₂ / β-PbO ₂ ) in the positive electrode active material is 0.60 or less. Positive electrode plate. The positive electrode active material is PbO ₂ Including
Α-PbO in the positive electrode active material ₂ And β-PbO ₂ Ratio of peak intensities of the X-ray diffraction pattern of (α-PbO) ₂ / Β-PbO ₂ ) Is 0.35 or more, the positive electrode plate according to any one of claims 1 to 3. A lead-acid battery comprising the positive electrode plate according to any one of claims 1 to 4.

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