JP6778386B2 - Lead-acid battery - Google Patents

Description

The present invention relates to a lead storage battery.

In recent years, various fuel efficiency improvement measures have been studied for automobiles in order to prevent air pollution or global warming. Examples of automobiles with fuel efficiency improvement measures include idling stop system vehicles (hereinafter referred to as "ISS vehicles") that reduce the operating time of the engine, and power generation control vehicles that reduce the power generation of the alternator by the power of the engine. Micro-hybrid vehicles are being considered.

In the ISS vehicle, the number of times the engine is started increases, so that the large current discharge of the lead storage battery is repeated. Further, in the ISS vehicle and the power generation control vehicle, the amount of power generated by the alternator is reduced, and the lead storage battery is charged intermittently, resulting in insufficient charging.

The lead-acid battery used as described above is used in a partially charged state called PSOC (Partial State Of Charge).

By the way, a lead-acid battery has, for example, a structure in which a positive electrode (positive electrode plate or the like), a negative electrode (negative electrode plate or the like), and a bag-shaped separator made of synthetic resin that separates both electrodes are laminated. As the separator, a microporous film with ribs is known, which is formed mainly of polyolefin, which is easy to integrally process ribs and bag processing, and has a main rib for contacting an electrode plate projected on one side of a flat sheet. Has been done. The separator made of the ribbed microporous film is usually designed so that the surface on which the main rib for contacting the electrode plate is projected abuts on the positive electrode plate. Further, the surface opposite to the surface on which the main rib for contacting the electrode plate is projected is a flat surface without ribs, and is designed to contact the negative electrode plate.

Generally, when charging a lead-acid battery, oxygen gas is generated from the positive electrode at the end of charging, so that the surface of the separator facing the positive electrode is in an oxidizing atmosphere. Therefore, the surface of the separator facing the positive electrode is more likely to be oxidized than the surface facing the negative electrode, the separator is deteriorated and becomes brittle, and its thickness is reduced so that holes are easily formed. As a result, a short circuit between the positive electrode and the negative electrode may become a problem.

Further, in a lead-acid battery, in repeated charging and discharging, water is generated at the time of discharging and sulfuric acid is generated at the time of charging. Since sulfuric acid has a higher specific gravity than water and tends to settle in the lower part, a stratification phenomenon occurs in which the concentration of the electrolytic solution (sulfuric acid) differs between the upper part and the lower part of the battery. Since the conventional engine vehicle is overcharged during traveling, the stratification is alleviated by the stirring action of the electrolytic solution by the oxygen gas and hydrogen gas generated from the positive electrode plate and the negative electrode plate at this time. However, under PSOC, the state of insufficient charging continues, so that the stirring action of the electrolytic solution by oxygen gas and hydrogen gas does not appear, and stratification is likely to occur. When stratification occurs, the concentration of the electrolytic solution in the upper part of the battery decreases, so that the amount of lead sulfate dissolved in the upper part of the battery increases, and a permeation short circuit is likely to occur.

On the other hand, in Patent Document 1 below, in order to suppress a dendrite short circuit, a separator composed of a raw material composition mainly composed of polyolefin, an inorganic powder and a plasticizer and having a specific structure is used. Is described.

Japanese Unexamined Patent Publication No. 2013-21115

By the way, according to the study by the present inventors, when silica is used as the inorganic powder contained in the separator, it becomes easy to cause a permeation short circuit. For example, in the technique described in Patent Document 1, the permeation short circuit is suppressed. Was found to be expected to be inadequate. Therefore, in recent years, lead-acid batteries have been required to further enhance the effect of suppressing short circuits as compared with the prior art.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a lead storage battery having an excellent effect of suppressing a short circuit even when a separator containing silica is used.

The lead-acid battery according to the present invention includes a positive electrode and a negative electrode facing each other via a separator, and an electrolytic solution, the separator containing polyolefin and silica, and the electrolytic solution containing aluminum ions.

The lead-acid battery according to the present invention is excellent in the effect of suppressing a short circuit even when a separator containing silica is used. Further, according to the lead storage battery according to the present invention, it is possible to obtain excellent battery characteristics while suppressing short circuits, and for example, it is possible to obtain excellent charge acceptability. Therefore, the SOC (State Of Charge), which tends to be low in ISS vehicles and micro-hybrid vehicles, is maintained at an appropriate level, especially after the active material is sufficiently activated by repeating charging and discharging to some extent from the initial state. can do. Further, according to the lead storage battery according to the present invention, it is possible to achieve both excellent charge acceptability and other excellent battery characteristics (discharge characteristics, cycle characteristics, etc.).

Further, according to the lead-acid battery according to the present invention, it is possible to suppress the shortening of the life of the lead-acid battery used under PSOC. The reason why the life of lead-acid batteries used under PSOC is shortened is that if charging and discharging are repeated in a state where charging is insufficient, lead sulfate generated on the negative electrode (negative electrode plate, etc.) at the time of discharging becomes coarse. This is probably because lead sulfate is difficult to return to the spongy metal lead, which is a charge product.

In elemental analysis by energy dispersive X-ray spectroscopy (EDX), the total mass of oxygen and silicon in the separator is preferably 30 to 80% by mass based on the total mass of carbon, oxygen and silicon. In this case, the effect of suppressing a short circuit is further excellent, and the strength of the separator can be improved.

The concentration of aluminum ions in the electrolytic solution is preferably 0.01 to 0.3 mol / L. In this case, the effect of suppressing a short circuit is further excellent, and the battery characteristics such as charge acceptability can be further improved.

The lead-acid battery according to the present invention may have an embodiment in which the silica is silica particles and the specific surface area of the silica particles is 100 to 400 m ² / g.

The separator may have a convex rib and a base portion that supports the rib. The height H of the rib is preferably 0.3 mm or more. The ratio H / T of the height H of the rib to the thickness T of the base portion is preferably 2.3 or more. The width of the upper base of the rib is preferably 0.1 to 2 mm.

The separator may have a bag shape that encloses at least one of the positive electrode and the negative electrode.

In the lead-acid battery according to the present invention, the negative electrode has a current collector and a negative electrode material held by the current collector, and the negative electrode material is composed of an active material, a sulfo group and a sulfonic acid base. It may be an embodiment containing a resin having at least one selected from the group.

According to the present invention, it is possible to provide a lead storage battery having an excellent effect of suppressing a short circuit even when a separator containing silica is used. Further, according to the lead storage battery according to the present invention, excellent battery characteristics (for example, charge acceptability) can be obtained while suppressing a short circuit. Further, according to the lead-acid battery according to the present invention, it is possible to achieve both excellent charge acceptability and other excellent battery characteristics (discharge characteristics, cycle characteristics, etc.). The lead-acid battery according to the present invention can be suitably used in automobiles such as ISS vehicles and micro-hybrid vehicles as a liquid lead-acid battery in which charging is intermittently performed and high-rate discharge is performed under PSOC. According to the present invention, it is possible to provide an application of a lead storage battery to a micro-hybrid vehicle. According to the present invention, it is possible to provide an application of a lead storage battery to an ISS vehicle.

It is a drawing which shows the separator. It is sectional drawing of a separator and an electrode. It is a drawing which shows the bag-shaped separator and the electrode accommodated in the bag-shaped separator.

Hereinafter, embodiments of the present invention will be described in detail. Since the specific gravity changes depending on the temperature, it is defined in this specification as the specific gravity converted at 20 ° C. Further, in the present specification, "silica" means a general term for silicon dioxide (SiO ₂ ) or a substance composed of silicon dioxide.

<Lead-acid battery>
The lead-acid battery according to the present embodiment includes a positive electrode (positive electrode plate or the like) and a negative electrode (negative electrode plate or the like) facing each other via a separator, and an electrolytic solution (sulfuric acid or the like), and the separator contains polyolefin and silica and is electrolyzed. The liquid contains aluminum ions.

The lead-acid battery according to the present embodiment includes, for example, an electric tank, an electrode (electrode plate, etc.), an electrolytic solution (sulfuric acid, etc.), and a separator, and has a positive electrode and a negative electrode as electrodes. The electrode, electrolytic solution and separator are housed in the battery case. Examples of the lead-acid battery according to the present embodiment include a liquid-type lead-acid battery and a control valve type lead-acid battery, and a liquid-type lead-acid battery is preferable.

The positive electrode and the negative electrode are laminated via a separator to form an electrode group (electrode plate group, etc.). The positive electrode has a current collector (positive electrode current collector) and a positive electrode material held by the current collector. The negative electrode has a current collector (negative electrode current collector) and a negative electrode material held by the current collector. In the present embodiment, the positive electrode material and the negative electrode material are, for example, electrode materials after chemical conversion. When the electrode material is unchemical, the electrode material (unchemical positive electrode material and unchemical negative electrode material) contains the raw materials thereof and the like. The current collector constitutes a conductive path for the current from the electrode material. As the basic configuration of the lead-acid battery, the same configuration as that of the conventional lead-acid battery can be used.

(Separator)
The separator blocks the electrical connection between the positive electrode and the negative electrode, and allows the sulfate ion of the electrolytic solution to permeate. The separator is preferably composed of a material mainly composed of polyolefin and silica (for example, the content (total amount) of polyolefin and silica is 50% by mass or more based on the total mass of the separator). As the polyolefin, for example, a homopolymer or copolymer of ethylene, propylene, butene, methylpentene or the like, or a mixture thereof can be used. Examples of the homopolymer include polyethylene, polypropylene, polybutene, polymethylpentene and the like. Among these, polyethylene is preferable from the viewpoint of excellent moldability and economy. Polyethylene has a lower melt molding temperature than polypropylene and has good productivity.

The weight average molecular weight of the polyolefin is preferably 500,000 or more, more preferably 1 million or more, from the viewpoint of excellent mechanical strength of the separator. The upper limit of the weight average molecular weight is not particularly limited, but from a practical point of view, it is preferably 5 million or less. The weight average molecular weight of the polyolefin can be measured, for example, by using a high temperature GPC apparatus using toluene or xylene as the eluent.

In this embodiment, it is preferable to use silica particles as silica. As the silica particles, particles having a fine particle size and having a pore structure inside and on the surface are preferable. The specific surface area of the silica particles is preferably 100 m ² / g or more. When the specific surface area is 100 m ² / g or more, the pore structure of the separator is further refined (complicated) and complicated to further enhance the short-circuit resistance, and the electrolyte holding power is enhanced, so that a large number of particles are present on the powder surface. By providing a hydrophilic group (-OH or the like), the hydrophilicity of the separator can be further enhanced. Further, the specific surface area of the silica particles is preferably 400 m ² / g or less from the viewpoint that the silica particles can be uniformly dispersed in the separator. From these viewpoints, the specific surface area of the silica particles is preferably 100 to 400 m ² / g. The specific surface area of the silica particles can be measured, for example, by the BET method.

The number of silica particles having a particle size (maximum diameter) of 2 μm or more in the separator is arbitrarily selected when the cross section of the separator is analyzed with a scanning electron microscope (SEM) from the viewpoint of excellent uniformity of separator strength. Within the range of 40 μm, the number is preferably 20 or less, and more preferably 10 or less.

In elemental analysis by energy dispersive X-ray spectroscopy (EDX), the total mass of oxygen and silicon (silicon) in the separator is used in the separator from the viewpoint of further improving the effect of suppressing short circuit and improving the strength of the separator. It is preferably in the following range based on the total mass of carbon, oxygen and silicon. The total mass of oxygen and silicon is preferably 30% by mass or more, more preferably 40% by mass or more, still more preferably 50% by mass or more. The total of the masses of oxygen and silicon may be 55% by mass or more, or 60% by mass or more. The total mass of oxygen and silicon is preferably 80% by mass or less, more preferably 75% by mass or less, still more preferably 70% by mass or less. The total of the masses of oxygen and silicon may be 65% by mass or less. The total mass of oxygen and silicon is preferably 30 to 80% by mass, more preferably 40 to 75% by mass, still more preferably 50 to 70% by mass. The total of the masses of oxygen and silicon may be 55-75 mass% or 60-65 mass%.

The masses of carbon, oxygen and silicon in the separator can be determined, for example, by analyzing the cross section of the separator by energy dispersive X-ray spectroscopy (EDX). That is, it is preferable that the total mass of oxygen and silicon is in the above range based on the total mass of carbon, oxygen and silicon detected when the cross section of the separator is analyzed by EDX.

The separator of the present embodiment can be obtained, for example, by melt-kneading a raw material composition mainly composed of polyolefin, silica and a plasticizer and molding it into a sheet-like product having a predetermined shape.

As the plasticizer, for example, a mineral oil such as an industrial lubricating oil made of saturated hydrocarbon (paraffin); a higher alcohol such as stearyl alcohol; an ester plasticizer such as dioctyl phthalate can be used. Of these, mineral oil is preferable because it is easy to reuse. The plasticizer is preferably blended in a raw material composition mainly composed of polyolefin, silica and a plasticizer in an amount of 30 to 70% by mass based on the total amount of the raw material composition.

The plasticizer is removed by melting and kneading a raw material composition mainly composed of polyolefin, silica and a plasticizer to form a sheet-like product having a predetermined shape, and then removing the plasticizer by, for example, extraction and removal using a solvent. Porousing can be achieved by removing the plasticizer, but in the lead-acid battery separator, the oxidation resistance can be improved by containing an appropriate amount of the plasticizer. The content of the plasticizer in the separator is preferably 5 to 30% by mass based on the total mass of the separator.

As the solvent used for extracting and removing the plasticizer, for example, a saturated hydrocarbon-based organic solvent such as hexane, heptane, octane, nonane, and decane can be used.

Separator can be used as a surfactant (hydrophilic agent), antioxidant, UV absorber, weather resistant agent, lubricant, antibacterial agent, fungicide, pigment, dye, colorant, antifogging agent, if necessary. Additives such as a matting agent may be contained as long as the object and effect of the present invention are not impaired.

The separator preferably has a convex rib and a base portion that supports the rib. Hereinafter, one aspect of the separator of the present embodiment will be described with reference to FIGS. 1 to 3.

FIG. 1A is a front view showing a separator, and FIG. 1B is a cross-sectional view of the separator. FIG. 2 is a cross-sectional view of the separator and the electrode. As shown in FIG. 1, the separator 10 includes a flat plate-shaped base portion 11, a plurality of convex ribs 12, and mini ribs 13. The base portion 11 supports the rib 12 and the mini rib 13. A plurality (many) ribs 12 are formed so as to extend in the longitudinal direction of the separator 10 at the center in the width direction of the separator 10. The plurality of ribs 12 are arranged substantially parallel to each other on one surface 10a of the separator 10. The distance between the ribs 12 is, for example, 3 to 15 mm. One end of the rib 12 in the height direction is integrated with the base portion 11, and the other end of the rib 12 in the height direction is in contact with one of the positive electrode and the negative electrode 14a (see FIG. 2). The base portion 11 faces the electrode 14a in the height direction of the rib 12. No ribs are arranged on the other surface 10b of the separator 10, and the other surface 10b of the separator 10 faces or is in contact with the other electrode 14b (see FIG. 2) of the positive electrode and the negative electrode.

A plurality (many) of the mini ribs 13 are formed so as to extend in the longitudinal direction of the separator 10 on both sides in the width direction of the separator 10. The mini rib 13 has a function of improving the separator strength in order to prevent the corners of the electrodes from breaking through the separator and short-circuiting when the lead-acid battery vibrates in the lateral direction. The height, width, and spacing of the mini ribs 13 are preferably smaller than those of the ribs 12. Further, the cross-sectional shape of the mini rib 13 may be the same as or different from that of the rib 12. The cross-sectional shape of the mini rib 13 is preferably a semicircular shape. Further, the mini rib 13 may not be formed in the separator 10.

The upper limit of the thickness T of the base portion 11 is preferably 0.4 mm or less, more preferably 0.3 mm or less, still more preferably 0.25 mm or less, from the viewpoint of obtaining more excellent charge acceptability and discharge characteristics. The lower limit of the thickness T of the base portion 11 is not particularly limited, but is preferably 0.05 mm or more, more preferably 0.1 mm or more, from the viewpoint of further excellent effect of suppressing a short circuit.

The upper limit of the height H of the rib 12 (height in the opposite direction of the base portion 11 and the electrode 14) H is preferably 1 mm or less, more preferably 0.8 mm or less, and 0, from the viewpoint of obtaining more excellent charge acceptability. 6 mm or less is more preferable. The lower limit of the height H of the rib 12 is preferably 0.3 mm or more, more preferably 0.4 mm or more, still more preferably 0.5 mm or more, from the viewpoint of suppressing oxidative deterioration at the positive electrode.

The lower limit of the ratio H / T of the height H of the rib 12 to the thickness T of the base portion 11 is preferably 2 or more from the viewpoint of excellent oxidation resistance of the separator. When the ratio H / T is 2 or more, it is presumed that the oxidation resistance of the separator is improved because a portion that does not come into contact with the electrode (for example, the positive electrode) can be sufficiently secured.

The lower limit of the ratio H / T is more preferably 2.3 or more, and further preferably 2.5 or more, from the viewpoint of excellent oxidation resistance and productivity of the separator. The upper limit of the ratio H / T is preferably 6 or less from the viewpoint of excellent rib shape retention and further excellent short circuit suppressing effect. When the ratio H / T is 6 or less, it is presumed that the short circuit is further suppressed because the distance between the positive electrode and the negative electrode is sufficient. Further, when the ratio H / T is 6 or less, it is presumed that the ribs are not damaged when the lead storage battery is assembled, and the battery characteristics such as charge acceptability are well maintained. The upper limit of the ratio H / T is more preferably 5 or less, still more preferably 4 or less, and particularly preferably 3 or less, from the viewpoint of further excellent effect of suppressing short circuit and excellent rib shape retention.

The upper base width B of the rib 12 (see FIG. 1B) is preferably 0.1 to 2 mm, more preferably 0.2 to 1 mm, from the viewpoint of excellent rib shape retention and oxidation resistance. 0.2 to 0.8 mm is more preferable. The lower bottom width A of the rib is preferably 0.2 to 4 mm, more preferably 0.3 to 2 mm, and even more preferably 0.4 to 1 mm from the viewpoint of excellent rib shape retention. The ratio (B / A) of the upper base width B and the lower base width A is preferably 0.1 to 1, more preferably 0.2 to 0.8, and 0.3 to 0.3, from the viewpoint of excellent rib shape retention. ~ 0.6 is more preferable.

The separator 10 preferably has a bag shape that encloses at least one of the positive electrode and the negative electrode. For example, it is preferable that one of the positive electrode and the negative electrode is housed in a bag-shaped separator and the other of the positive electrode and the negative electrode is alternately laminated. For example, when a bag-shaped separator is applied to the positive electrode, the positive electrode may penetrate the separator due to the elongation of the positive electrode current collector, so that the negative electrode is preferably housed in the bag-shaped separator.

As the separator 10, a microporous polyethylene sheet can be used. Further, as the separator 10, a microporous polyethylene sheet; a glass fiber and acid-resistant paper bonded together can be used. The separator is preferably cut according to the length of the negative electrode (negative electrode plate, etc.) during the step of laminating the electrodes (electrode plate, etc.). Further, the cut separator 10 may be folded in two and crimped on both sides to wrap the negative electrode.

FIG. 3 is a drawing showing a bag-shaped separator 20 and an electrode (for example, a negative electrode) 14 housed in the separator 20. As shown in FIG. 1A, the separator 10 used for manufacturing the separator 20 is formed, for example, in the shape of a long sheet. In the separator 20 shown in FIG. 3, the separator 10 is cut to an appropriate length, folded in half in the longitudinal direction of the separator 10, the electrodes 14 are arranged and overlapped inside the separator 10, and both sides are mechanically sealed, crimped or heat-treated. It is obtained by welding (for example, reference numeral 22 in FIG. 3 indicates a mechanical seal portion).

(Electrolytic solution)
The electrolytic solution of the lead storage battery according to the present embodiment contains aluminum ions. Since the electrolytic solution contains aluminum ions, an excellent short-circuit suppressing effect can be obtained even when a separator containing silica is used. The reason why a short circuit is likely to occur when a separator containing silica is used and the reason why the occurrence of a short circuit can be suppressed by the electrolytic solution containing aluminum ions are not clear, but the present inventors speculate as follows. To do.

First, during the discharge reaction, the positive electrode side tends to have an alkaline atmosphere, and when aluminum ions are not present in the electrolytic solution, silica tends to dissolve when it becomes alkaline. It is presumed that when silica is dissolved, the separator shrinks and the thickness of the separator decreases, so that a short circuit is likely to occur. Further, when the pH rises (pH shifts to the alkaline side) due to the consumption of hydrogen ions due to the discharge reaction of the positive electrode, the solubility of lead sulfate increases in the positive electrode, and the solubility and the pH decrease during charging (pH decreases). It is presumed that due to the difference from the solubility of lead sulfate when shifting to the acidic side), lead sulfate precipitates are likely to occur inside the separator, and the short circuit is accelerated.

On the other hand, in the present embodiment, since the electrolytic solution contains aluminum ions, an aluminum compound such as aluminum hydroxide is precipitated inside the separator during discharge. Since the dissolution of silica is suppressed by the precipitation of the aluminum compound such as aluminum hydroxide in this way, the thickness of the separator can be maintained. Further, since the increase in pH of the electrolytic solution (the pH shifts to the alkaline side) due to the precipitation reaction of an aluminum compound such as aluminum hydroxide can be alleviated, the increase in the solubility of lead sulfate can be suppressed. From these, it is presumed that the presence of aluminum ions in the electrolytic solution can suppress a short circuit.

The aluminum ion concentration of the electrolytic solution is preferably 0.01 mol / L or more based on the total amount of the electrolytic solution from the viewpoint of further excellent effect of suppressing short circuit and further improving battery characteristics such as charge acceptability. 0.02 mol / L or more is more preferable, and 0.05 mol / L or more is further preferable. The aluminum ion concentration of the electrolytic solution may be 0.08 mol / L or more, 0.1 mol / L or more, 0.12 mol / L or more, or 0.14 mol / L. It may be more than 0.15 mol / L or more. The aluminum ion concentration of the electrolytic solution is preferably 0.3 mol / L or less based on the total amount of the electrolytic solution from the viewpoint of further excellent effect of suppressing short circuit and further improving charge acceptability and cycle characteristics. .25 mol / L or less is more preferable, and 0.2 mol / L or less is further preferable. From these viewpoints, the aluminum ion concentration of the electrolytic solution is preferably 0.01 to 0.3 mol / L, more preferably 0.02 to 0.25 mol / L, and 0.05 to 0.05 to L, based on the total amount of the electrolytic solution. 0.2 mol / L is more preferable. The aluminum ion concentration of the electrolytic solution may be 0.08 to 0.2 mol / L, 0.1 to 0.2 mol / L, or 0.12 to 0.2 mol / L. It may be 0.14 to 0.2 mol / L, or 0.15 to 0.2 mol / L. The aluminum ion concentration of the electrolytic solution can be measured by, for example, ICP emission spectroscopic analysis (high frequency inductively coupled plasma emission spectroscopy).

It is presumed that the mechanism for further excellent short-circuit suppressing effect when the aluminum ion concentration of the electrolytic solution is within the predetermined range is as described above regarding the use of aluminum ions. The details of the mechanism for improving charge acceptability are not clear, but it is speculated as follows. That is, when the aluminum ion concentration is within the predetermined range, the solubility of crystalline lead sulfate, which is a discharge product, in the electrolytic solution is increased under an arbitrary low SOC, or due to the high ionic conductivity of aluminum ions. Since the diffusivity of the electrolytic solution into the electrode active material is improved, it is presumed that the charge acceptability is improved.

The electrolytic solution contains, for example, aluminum ions and sulfuric acid. The electrolytic solution may further contain ions other than aluminum ions (sodium ion, potassium ion, phosphate ion, etc.), and preferably contains sodium ions.

(Positive material)
[Positive electrode active material]
The positive electrode material contains a positive electrode active material. The positive electrode active material can be obtained by aging and drying a positive electrode material paste containing a raw material for the positive electrode active material to obtain an unchemicald positive electrode active material, and then chemicalizing the unchemicald positive electrode active material. The positive electrode active material after chemical conversion preferably contains β-lead dioxide (β-PbO ₂ ), and may further contain α-lead dioxide (α-PbO ₂ ). The raw material for the positive electrode active material is not particularly limited, and examples thereof include lead powder. As the lead powder, 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). ). Lead tan (Pb ₃ O ₄ ) may be used as a raw material for the positive electrode active material. The unchemical positive electrode material preferably contains an unchemical positive electrode active material containing tribasic lead sulfate as a main component.

The average particle size of the positive electrode active material is preferably 0.3 μm or more, more preferably 0.5 μm or more, still more preferably 0.7 μm or more, from the viewpoint of further improving charge acceptability and cycle characteristics. The average particle size of the positive electrode active material is preferably 2.5 μm or less, more preferably 2 μm or less, still more preferably 1.5 μm or less, from the viewpoint of further improving the cycle characteristics. The average particle size of the positive electrode active material is the average particle size of the positive electrode active material in the positive electrode material after chemical conversion. The average particle size of the positive electrode active material is, for example, the long side of all the active material particles in the scanning electron micrograph (1000 times) of the positive electrode material in the center of the positive electrode after chemical conversion in the range of 10 μm in length × 10 μm in width. The value of the length (maximum particle size) can be obtained as a numerical value obtained by arithmetically averaging.

The content of the positive electrode active material is preferably 95% by mass or more based on the total mass of the positive electrode material from the viewpoint of further excellent battery characteristics (capacity, low temperature high rate discharge performance, charge acceptability, cycle characteristics, etc.). It is more preferably mass% or more, and further preferably 99% by mass or more. The upper limit of the content of the positive electrode active material may be 100% by mass or less. The content of the positive electrode active material is the content of the positive electrode active material in the positive electrode material after chemical conversion.

[Positive electrode additive]
The positive electrode material may further contain an additive. Examples of the additive include carbon materials (carbonaceous conductive materials, excluding carbon fibers), reinforcing short fibers, and the like. Examples of the carbon material include carbon black and graphite. Examples of carbon black include furnace black (Ketjen black, etc.), channel black, acetylene black, thermal black, and the like. Examples of the reinforcing short fibers include acrylic fibers, polyethylene fibers, polypropylene fibers, polyethylene terephthalate fibers, carbon fibers and the like.

[Physical properties of positive electrode material]
The lower limit of the specific surface area of the positive electrode material is preferably 3 m ² / g or more, more preferably 4 m ² / g or more, still more preferably 5 m ² / g or more, from the viewpoint of further excellent charge acceptability. The upper limit of the specific surface area of the cathode material is not particularly limited, from the viewpoint of excellent practical point of view and utilization, preferably ^{15 m} 2 / g or less, more preferably ^13m 2 / g or less, it is ^12m 2 / g or less More preferred. The specific surface area of the positive electrode material is the specific surface area of the positive electrode material after chemical conversion. The specific surface area of the positive electrode material is, for example, a method of adjusting the amount of sulfuric acid and water added when preparing the positive electrode material paste, a method of refining the active material at the stage of the unchemicald positive electrode active material, and changing the chemical conversion conditions. It can be adjusted by a method or the like.

The specific surface area of the positive electrode material can be measured by, for example, 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. Specifically, the measurement is performed based on the following BET formula.

Relationship of the following formula (1), _P / P _o is established well in the range of 0.05 to 0.35. The details of each code in the equation (1) are as follows.
P: adsorption equilibrium pressure P o when an adsorption equilibrium state at a constant _temperature: the saturated vapor pressure at the adsorption temperature V: adsorption equilibrium pressure adsorption amount of P V _m: monomolecular monolayer adsorption amount (gas molecules solid surface Adsorption amount when forming a layer)
C: BET constant (parameter regarding the interaction between the solid surface and the adsorbed substance)

The following formula (2) can be obtained by modifying the formula (1) (dividing the numerator denominator on the left side by P). In the specific surface area meter used for the measurement, gas molecules having a known adsorption area are adsorbed on the sample, and the relationship between the adsorption amount (V) and the relative pressure (P / _Po ) is measured. Than the measured V and _P / P _o, to plot the left side and the P / Po of the formula (2). Here, assuming that the gradient is s, the following equation (3) is derived from the equation (2). Assuming that the intercept is i, the intercept i and the gradient s are as shown in the following equations (4) and (5), respectively.

By modifying the formulas (4) and (5), the following formulas (6) and (7) are obtained, respectively, and the following formula (8) for obtaining the adsorption amount V _m of the monolayer is obtained. That is, when the adsorption amount V at a certain relative pressure P / _Po is measured at several points and the gradient and intercept of the plot are obtained, the adsorption amount V _{m of the} monolayer is obtained.

The total surface area Total (m ² ) of the sample is calculated by the following formula (9), and the specific surface area S (m ² / g) is calculated from the total surface area Total by the following formula (10). In the formula (9), N indicates the Avogadro number, ACS indicates the adsorption cross-sectional area (m ² ), and M indicates the molecular weight. Further, in the formula (10), w represents the sample amount (g).

The porosity of the positive electrode material is preferably 50% by volume or more, more preferably 55% by volume or more, from the viewpoint that the region in which sulfuric acid enters the pores (pores) in the positive electrode material increases and the capacity tends to increase. The upper limit of the porosity of the positive electrode material is not particularly limited, but 70% by volume or less is preferable from the viewpoint that the amount of sulfuric acid impregnated into the pores in the positive electrode material is appropriate and the bonding force between the active materials can be maintained well. .. The upper limit of the porosity is more preferably 60% by volume or less from a practical point of view. The porosity of the positive electrode material is the porosity of the positive electrode material after chemical conversion. The porosity of the positive electrode material is, for example, a value (volume-based ratio) obtained from mercury porosimeter measurement. The porosity of the positive electrode material can be adjusted, for example, by the amount of dilute sulfuric acid added when the positive electrode material paste is prepared.

(Negative electrode material)
[Negative electrode active material]
The negative electrode material contains a negative electrode active material. The negative electrode active material can be obtained by aging and drying a negative electrode material paste containing a raw material for the negative electrode active material to obtain a non-chemical negative electrode active material, and then chemicalizing the unchemicald negative electrode active material. Examples of the negative electrode active material after chemical conversion include spongy lead and the like. The spongy lead reacts with sulfuric acid in the electrolytic solution and tends to gradually change to lead sulfate (PbSO ₄ ). Examples of the raw material for the negative electrode active material include lead powder and the like. As the lead powder, 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 unchemical negative electrode active material is composed of, for example, basic lead sulfate and metallic lead, and a lower oxide.

The average particle size of the negative electrode active material is preferably 0.3 μm or more, more preferably 0.5 μm or more, still more preferably 0.7 μm or more, from the viewpoint of further improving charge acceptability and cycle characteristics. The average particle size of the negative electrode active material is preferably 2.5 μm or less, more preferably 2 μm or less, still more preferably 1.5 μm or less, from the viewpoint of further improving the cycle characteristics. The average particle size of the negative electrode active material is the average particle size of the negative electrode active material in the negative electrode material after chemical conversion. The average particle size of the negative electrode active material is, for example, the long side of all the active material particles in the scanning electron micrograph (1000 times) of the negative electrode material in the center of the negative electrode after chemical conversion in the range of 10 μm in length × 10 μm in width. The value of the length (maximum particle size) can be obtained as a numerical value obtained by arithmetically averaging.

The content of the negative electrode active material is preferably 93% by mass or more based on the total mass of the negative electrode material from the viewpoint of further excellent battery characteristics (capacity, low temperature high rate discharge performance, charge acceptability, cycle characteristics, etc.), 95 It is more preferably mass% or more, and further preferably 98% by mass or more. The upper limit of the content of the negative electrode active material may be 100% by mass or less. The content of the negative electrode active material is the content of the negative electrode active material in the negative electrode material after chemical conversion.

[Negative electrode additive]
The negative electrode material may further contain an additive. As the additive, a resin having at least one selected from the group consisting of a sulfonic acid group (sulfonic acid group, sulfo group) and a sulfonic acid base (group in which hydrogen of the sulfonic acid group is replaced with an alkali metal, etc.) (sulfon group and /). Alternatively, a resin having a sulfonic acid base); barium sulfate; a carbon material (carbonaceous conductive material; excluding carbon fibers); short fibers for reinforcement and the like can be mentioned. When the negative electrode material contains a resin having at least one selected from the group consisting of a sulfone group and a sulfonic acid base, the charge acceptability can be further improved.

Examples of the resin having a sulfonic acid group and / or a sulfonic acid base include a bisphenol resin having a sulfonic acid group and / or a sulfonic acid base (hereinafter, simply referred to as “bisphenol resin”), lignin sulfonic acid, lignin sulfonate and the like. Be done. Ligno sulfonic acid is a compound in which a part of the decomposition product of lignin is sulfonated. Examples of the lignin sulfonate include potassium lignin sulfonate and sodium lignin sulfonate. Among these, bisphenol-based resins are preferable from the viewpoint of further improving charge acceptability.

The bisphenol resin is selected from the group consisting of bisphenol compounds, at least one selected from the group consisting of aminoalkyl sulfonic acid, aminoalkyl sulfonic acid derivative, aminoaryl sulfonic acid and aminoaryl sulfonic acid derivative, and the group consisting of formaldehyde and formaldehyde derivative. It is preferable that the resin is obtained by reacting with at least one of the above.

The bisphenol compound is a compound having two hydroxyphenyl groups. Examples of bisphenol compounds include 2,2-bis (4-hydroxyphenyl) propane (also referred to as "bisphenol A"), bis (4-hydroxyphenyl) methane, and 1,1-bis (4-hydroxyphenyl) ethane, 2. , 2-bis (4-hydroxyphenyl) hexafluoropropane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 2,2-bis (4-hydroxyphenyl) butane, bis (4-hydroxyphenyl) ) Diphenylmethane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, bis (4-hydroxyphenyl) sulfone ("bisphenol S" Also called) and the like.

Examples of the aminoalkyl sulfonic acid include aminomethanesulfonic acid, 2-aminoethanesulfonic acid, 3-aminopropanesulfonic acid, 2-methylaminoethanesulfonic acid and the like. The aminoalkyl sulfonic acid derivative, a compound wherein the hydrogen atom of the aminoalkyl sulfonic acid being substituted by an alkyl group (e.g., an alkyl group having 1 to 5 carbon atoms) or the like, a sulfonic group of the amino alkyl sulfonic acid (-SO 3 _H) Examples thereof include an alkali metal salt in which a hydrogen atom is replaced with an alkali metal (for example, sodium or potassium). Examples of the aminoarylsulfonic acid include aminobenzenesulfonic acid (4-aminobenzenesulfonic acid and the like), aminonaphthalenesulfonic acid and the like. The aminoaryl sulfonic acid derivative, a compound wherein the hydrogen atom of the amino aryl sulfonic acid being substituted by an alkyl group (e.g., an alkyl group having 1 to 5 carbon atoms) or the like, a sulfonic group of aminoaryl sulfonic acid (-SO 3 _H) Examples thereof include an alkali metal salt in which a hydrogen atom is replaced with an alkali metal (for example, sodium or potassium).

Examples of the formaldehyde derivative include paraformaldehyde, hexamethylenetetramine, trioxane and the like.

The bisphenol resin preferably has at least one selected from the group consisting of the structural unit represented by the following formula (I) and the structural unit represented by the following formula (II).

［式（Ｉ）中、Ｘ^１は、２価の基を示し、Ａ^１は、炭素数１〜４のアルキレン基、又は、アリーレン基を示し、Ｒ^１１は、アルカリ金属又は水素原子を示し、Ｒ^１２は、メチロール基（−ＣＨ_２ＯＨ）を示し、Ｒ^１３及びＲ^１４は、それぞれ独立にアルカリ金属又は水素原子を示し、ｎ１１は、１〜６００の整数を示し、ｎ１２は、１〜３の整数を示し、ｎ１３は、０又は１を示す。］

[In the formula (I), X ¹ represents a divalent group, A ¹ represents an alkylene group having 1 to 4 carbon atoms or an arylene group, and R ¹¹ represents an alkali metal or a hydrogen atom. R ¹² represents a methylol group (-CH ₂ OH), R ¹³ and R ¹⁴ each independently represent an alkali metal or a hydrogen atom, n 11 represents an integer of 1 to 600, and n 12 represents 1-3. Indicates an integer of, and n13 indicates 0 or 1. ]

［式（ＩＩ）中、Ｘ^２は、２価の基を示し、Ａ^２は、炭素数１〜４のアルキレン基、又は、アリーレン基を示し、Ｒ^２１は、アルカリ金属又は水素原子を示し、Ｒ^２２は、メチロール基（−ＣＨ_２ＯＨ）を示し、Ｒ^２３及びＲ^２４は、それぞれ独立にアルカリ金属又は水素原子を示し、ｎ２１は、１〜６００の整数を示し、ｎ２２は、１〜３の整数を示し、ｎ２３は、０又は１を示す。］

[In formula (II), X ² represents a divalent group, A ² represents an alkylene group having 1 to 4 carbon atoms or an arylene group, and R ²¹ represents an alkali metal or a hydrogen atom. R ²² represents a methylol group (-CH ₂ OH), R ²³ and R ²⁴ each independently represent an alkali metal or a hydrogen atom, n21 represents an integer of 1 to 600, and n ²² represents 1-3. Indicates an integer of, and n23 indicates 0 or 1. ]

The ratio of the structural unit represented by the formula (I) and the structural unit represented by the formula (II) is not particularly limited and may change depending on the synthesis conditions and the like. As the bisphenol resin, a resin having only one of the structural unit represented by the formula (I) and the structural unit represented by the formula (II) may be used.

Examples of X ¹ and X ² include an alkylidene group (methylidene group, ethylidene group, isopropylidene group, sec-butylidene group, etc.), a cycloalkylidene group (cyclohexylidene group, etc.), and a phenylalkylidene group (diphenylmethylidene group, etc.). Organic groups such as phenylethylidene group); sulfonyl group, isopropylidene group (-C (CH ₃ ) _2- ) is preferable from the viewpoint of further excellent charge acceptability, and sulfonyl group is more excellent from the viewpoint of discharge characteristics. A group (-SO _2- ) is preferred. X ¹ and X ² may be substituted with a halogen atom such as a fluorine atom. When X ¹ and X ² are cycloalkylidene groups, the hydrocarbon ring may be substituted with an alkyl group or the like.

Examples of A ¹ and A ² include an alkylene group having 1 to 4 carbon atoms such as a methylene group, an ethylene group, a propylene group and a butylene group; and a divalent arylene group such as a phenylene group and a naphthylene group. The arylene group may be substituted with an alkyl group or the like.

Examples of the alkali metals of R ¹¹ , R ¹³ , R ¹⁴ , R ²¹ , R ²³ and R ²⁴ include sodium and potassium. n11 and n21 are preferably 5 to 300 from the viewpoint of further excellent cycle characteristics and solubility in a solvent. n12 and n22 are preferably 1 or 2, and more preferably 1 from the viewpoint of improving charge acceptability, discharge characteristics, and cycle characteristics in a well-balanced manner. Although n13 and n23 vary depending on the production conditions, 0 is preferable from the viewpoint of further excellent cycle characteristics and excellent storage stability of the bisphenol resin.

The weight average molecular weight of a resin having a sulfone group and / or a sulfonic acid base (bisphenol resin, etc.) is to prevent the resin having a sulfone group and / or a sulfonic acid base from eluting from an electrode to an electrolytic solution in a lead storage battery. From the viewpoint that the cycle characteristics are easily improved, 3000 or more is preferable, 10,000 or more is more preferable, 20000 or more is further preferable, and 30,000 or more is particularly preferable. The weight average molecular weight of the resin having a sulfone group and / or a sulfonic acid base is 200,000 or less from the viewpoint that the cycle characteristics can be easily improved by suppressing the decrease in adsorptivity to the electrode active material and the decrease in dispersibility. Is preferable, 150,000 or less is more preferable, and 100,000 or less is further preferable.

The weight average molecular weight of the resin having a sulfone group and / or a sulfonic acid base can be measured, for example, by gel permeation chromatography (hereinafter referred to as “GPC”) under the following conditions. (GPC condition)
Equipment: High Performance Liquid Chromatograph LC-2200 Plus (manufactured by JASCO Corporation)
Pump: PU-2080
Differential refractometer: RI-2031
Detector: Ultraviolet-visible absorptiometer UV-2075 (λ: 254 nm)
Column oven: CO-2065
Columns: TSKgel SuperAW (4000), TSKgel SuperAW (3000), TSKgel SuperAW (2500) (manufactured by Tosoh Corporation)
Column temperature: 40 ° C
Eluent: Methanol solution containing LiBr (10 mM) and triethylamine (200 mM) Flow velocity: 0.6 mL / min Molecular weight Standard sample: Polyethylene glycol (Molecular weight: 1.10 x 10 ⁶ , 5.80 x 10 ⁵ , 2.55 × 10 ⁵ , 1.46 × 10 ⁵ , 1.01 × 10 ⁵ , 4.49 × 10 ⁴ , 2.70 × 10 ⁴ , 2.10 × 10 ⁴ ; manufactured by Toso Co., Ltd., diethylene glycol (molecular weight: 1) .06 × 10 ² ; manufactured by Kishida Chemical Co., Ltd.), dibutyl hydroxytoluene (molecular weight: 2.20 × 10 ² ; manufactured by Kishida Chemical Co., Ltd.)

When a resin having a sulfone group and / or a sulfonic acid base is used, the content of the resin having a sulfone group and / or a sulfonic acid base is based on the total mass of the negative electrode material from the viewpoint of obtaining more excellent charge acceptability. In terms of solid content, 0.01% by mass or more is preferable, 0.05% by mass or more is more preferable, and 0.1% by mass or more is further preferable. The content of the resin having a sulfone group and / or a sulfonic acid base is preferably 2% by mass or less in terms of solid content, preferably 1% by mass or less, based on the total mass of the negative electrode material from the viewpoint of obtaining more excellent discharge characteristics. Is more preferable, and 0.3% by mass or less is further preferable.

Examples of the carbon material include carbon black and graphite. Examples of carbon black include furnace black (Ketjen black, etc.), channel black, acetylene black, thermal black, and the like. Examples of the reinforcing short fibers include acrylic fibers, polyethylene fibers, polypropylene fibers, polyethylene terephthalate fibers, carbon fibers and the like.

[Physical properties of negative electrode material]
The specific surface area of the negative electrode material is preferably 0.4 m ² / g or more, more preferably 0.5 m ² / g or more, and 0.6 m ² / g or more, from the viewpoint of enhancing the reactivity between the electrolytic solution and the negative electrode active material. Is more preferable. The specific surface area of the negative electrode material, from the further suppression of the contraction of the negative electrode at the time of the cycle is preferably not more than ^2m 2 / g, more preferably not more than 1.8 m ² / g, more preferably not more than 1.5 m ² / g. The specific surface area of the negative electrode material is the specific surface area of the negative electrode material after chemical conversion. The specific surface area of the negative electrode material changes, for example, a method of adjusting the amount of sulfuric acid and water added when preparing the negative electrode material paste, a method of refining the active material at the stage of the unchemicald negative electrode active material, and the chemical conversion conditions. It can be adjusted by the method. The specific surface area of the negative electrode material can be measured by, for example, the BET method.

(Current collector)
Examples of the method for manufacturing the current collector include a casting method, an expanding method, and a punching method. Examples of the material of the current collector include lead-calcium-tin alloys and lead-antimony alloys. A small amount of selenium, silver, bismuth and the like can be added to these. For example, a current collector can be obtained by forming these materials in a grid shape or a mesh shape by the above-mentioned manufacturing method. The materials and / or manufacturing methods of the positive electrode and negative electrode current collectors may be the same or different from each other.

<Manufacturing method of lead-acid battery>
The method for manufacturing a lead-acid battery according to the present embodiment includes, for example, an electrode manufacturing step for obtaining electrodes (positive electrode and negative electrode) and an assembly step for assembling constituent members including the electrodes to obtain a lead-acid battery.

In the electrode manufacturing process, for example, the electrode material paste (positive electrode material paste and negative electrode material paste) is filled in a current collector (cast lattice body obtained by a casting method, expanded lattice body obtained by an expand method, etc.), and then aged and aged. A non-chemical electrode is obtained by drying. The positive electrode material paste contains, for example, a raw material (lead powder or the like) for the positive electrode active material, and may further contain other additives. The negative electrode material paste contains a raw material (lead powder, etc.) for the negative electrode active material, and preferably contains a resin having a sulfone group and / or a sulfonic acid base (bisphenol resin, etc.) as a dispersant. , Other additives may be further contained.

The positive electrode material paste for obtaining the positive electrode material can be obtained, for example, by the following method. In producing the positive electrode material paste, lead tan (Pb ₃ O ₄ ) may be used as a raw material for the positive electrode active material from the viewpoint of shortening the chemical conversion time.

First, an additive (reinforcing short fibers or the like) is added to the raw material of the positive electrode active material and dry-mixed to obtain a mixture. Then, sulfuric acid (dilute sulfuric acid or the like) and a solvent (water such as ion-exchanged water, an organic solvent, etc.) are added to this mixture and kneaded to obtain a positive electrode material paste.

An unchemicald positive electrode can be obtained by aging and drying after filling the current collector with the positive electrode material paste.

When reinforcing short fibers are used in the positive electrode material paste, the blending amount of the reinforcing short fibers is preferably 0.005 to 0.3% by mass based on the total mass of the raw material (lead powder, etc.) of the positive electrode active material. More preferably, 0.05 to 0.3% by mass.

The aging conditions for obtaining an unmodified positive electrode are preferably 15 to 60 hours in an atmosphere having a temperature of 35 to 85 ° C. and a relative humidity of 50 to 98 RH%. The drying conditions are preferably 15 to 30 hours at a temperature of 45 to 80 ° C.

The negative electrode material paste can be obtained, for example, by the following method. First, an additive (resin having a sulfone group and / or a sulfonic acid base, a carbon material, reinforcing short fibers, barium sulfate, etc.) is added to the raw material of the negative electrode active material and dry-mixed to obtain a mixture. Then, sulfuric acid (dilute sulfuric acid or the like) and a solvent (water such as ion-exchanged water, an organic solvent, etc.) are added to this mixture and kneaded to obtain a negative electrode material paste. An unmodified negative electrode can be obtained by filling the current collector with this negative electrode material paste and then aging and drying it.

When a resin having a sulfone group and / or a sulfonic acid base (bisphenol resin or the like), a carbon material, reinforcing short fibers or barium sulfate is used in the negative electrode material paste, the blending amount of each component is preferably in the following range. The blending amount of the resin having a sulfonic acid group and / or a sulfonic acid base is preferably 0.01 to 2.0% by mass in terms of resin solid content, based on the total mass of the raw material (lead powder, etc.) of the negative electrode active material. , 0.05 to 1.0% by mass, more preferably 0.1 to 0.5% by mass, and particularly preferably 0.1 to 0.3% by mass. The blending amount of the carbon material is preferably 0.1 to 3% by mass, more preferably 0.2 to 1.4% by mass, based on the total mass of the raw material (lead powder or the like) of the negative electrode active material. The blending amount of the reinforcing short fibers is preferably 0.05 to 0.3% by mass based on the total mass of the raw material (lead powder or the like) of the negative electrode active material. The blending amount of barium sulfate is preferably 0.01 to 2.0% by mass, more preferably 0.01 to 1.0% by mass, based on the total mass of the raw material (lead powder or the like) of the negative electrode active material.

The aging conditions for obtaining an unmodified negative electrode are preferably 15 to 30 hours in an atmosphere having a temperature of 45 to 65 ° C. and a relative humidity of 70 to 98 RH%. The drying conditions are preferably 15 to 30 hours at a temperature of 45 to 60 ° C.

In the assembly process, for example, the unchemical negative electrode and the unchemical positive electrode produced as described above are alternately laminated via a separator, and the current collectors of electrodes having the same polarity are connected (welded, etc.) with a strap. Obtain a group of electrodes. This group of electrodes is arranged in the battery case to produce an unchemical battery. Next, after injecting an electrolytic solution into a non-chemical battery, a direct current is applied to form an electric tank. A lead storage battery can be obtained by adjusting the specific gravity of the electrolytic solution after chemical conversion to an appropriate specific gravity.

The electrolytic solution contains, for example, sulfuric acid and aluminum ions, and can be obtained by mixing sulfuric acid and aluminum sulfate powder. Aluminum sulfate to be dissolved in the electrolytic solution can be added as an anhydride or a hydrate.

The specific gravity of the electrolytic solution (electrolyte solution containing aluminum ions) after chemical conversion is preferably in the following range. The specific gravity of the electrolytic solution is preferably 1.25 or more, more preferably 1.26 or more, still more preferably 1.27 or more, and 1.275 or more, from the viewpoint of further suppressing permeation short circuit or freezing and further excellent discharge characteristics. Is particularly preferable. The specific gravity of the electrolytic solution is preferably 1.33 or less, more preferably 1.32 or less, further preferably 1.31 or less, and particularly preferably 1.30 or less, from the viewpoint of further improving charge acceptability and cycle characteristics. The value of the specific gravity of the electrolytic solution can be measured by, for example, a floating hydrometer or a digital hydrometer manufactured by Kyoto Denshi Kogyo Co., Ltd.

The battery case can store electrodes (electrode plates, etc.) inside. From the viewpoint of easy storage of the electrodes, the battery case preferably has a box body having an open upper surface and a lid body covering the upper surface of the box body. An adhesive, heat welding, laser welding, ultrasonic welding, or the like can be appropriately used for bonding the box body and the lid body. The shape of the battery case is not particularly limited, but a square shape is preferable so that the invalid space is reduced when the electrodes (plate-shaped electrode plate, etc.) are stored.

The material of the battery case is not particularly limited, but needs to be resistant to an electrolytic solution (dilute sulfuric acid or the like). Specific examples of the material of the battery case include PP (polypropylene), PE (polyethylene), ABS resin and the like. When the material is PP, it is advantageous in terms of acid resistance, processability and economy. PP is advantageous in terms of workability as compared with ABS resin, which is difficult to heat-weld the battery case and the lid.

When the battery case is composed of a box body and a lid body, the materials of the box body and the lid body may be the same material or different materials from each other. As the material of the box body and the lid body, materials having the same coefficient of thermal expansion are preferable from the viewpoint of not generating unreasonable stress.

The chemical conversion conditions and the specific gravity of sulfuric acid can be adjusted according to the properties of the electrode active material. Further, the chemical conversion treatment is not limited to being carried out after the assembly step, and may be carried out after aging and drying in the electrode manufacturing step (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.

<Manufacturing lead-acid batteries>
(Example 1)
[Preparation of positive electrode plate]
Lead powder and lead tan (Pb ₃ O ₄ ) were used as raw materials for the positive electrode active material (lead powder: lead tan = 96: 4 (mass ratio)). The raw material of the positive electrode active material, 0.07% by mass of short reinforcing fibers (acrylic fibers) based on the total mass of the raw material of the positive electrode active material, and water were mixed and kneaded. Subsequently, dilute sulfuric acid (specific gravity 1.280) was added little by little and kneaded to prepare a positive electrode material paste. This positive electrode material paste was filled in an expanded lattice body produced by subjecting a rolled sheet made of a lead alloy to an expanding process. Next, the lattice body (current collector) filled with the positive electrode material paste was aged for 24 hours in an atmosphere having a temperature of 50 ° C. and a humidity of 98%. Then, it was dried to prepare an unchemical positive electrode plate.

[Manufacturing of negative electrode plate]
Lead powder was used as a raw material for the negative electrode active material. Vispers P215 (a condensate of a bisphenol compound, aminobenzenesulfonic acid and formaldehyde, trade name, manufactured by Nippon Paper Co., Ltd.) was 0.2% by mass (solid content equivalent), and short reinforcing fibers (acrylic fibers) were 0. A mixture containing 1% by mass, 1.0% by mass of barium sulfate, and 0.2% by mass of a carbon material (furness black) was added to the lead powder and then dry-mixed (the blending amount is the raw material of the negative electrode active material). The amount is based on the total mass). Next, water was added and then kneaded. Subsequently, dilute sulfuric acid (specific gravity 1.280) was added little by little and kneaded to prepare a negative electrode material paste. This negative electrode material paste was filled in an expanded lattice body produced by subjecting a rolled sheet made of a lead alloy to an expanding process. Next, the lattice body (current collector) filled with the negative electrode material paste was aged for 24 hours in an atmosphere having a temperature of 50 ° C. and a humidity of 98%. Then, it was dried to prepare an unchemical negative electrode plate.

[Preparation of separator]
A separator was prepared by processing a sheet-like material containing polyethylene and silica particles and having a plurality of linear ribs formed on one surface into a bag shape so that the surface on which the ribs are formed is on the outside. (See FIGS. 1 and 3). Details of the separator are shown below.
-Total thickness: 0.75 mm (base thickness T: 0.2 mm, rib height H: 0.55 mm, H / T = 2.75)
-Rib spacing: 7.35 mm, rib upper base width B: 0.4 mm, rib lower base width A: 0.8 mm
Silica particles: The number of silica particles having a particle size (maximum diameter) of 2 μm or more is 9 within the range of 30 μm × 40 μm, which is arbitrarily selected when the cross section of the separator is analyzed by a scanning electron microscope (SEM). there were.

[Battery assembly]
An unchemical negative electrode plate was housed in the obtained bag-shaped separator. Next, five unchemical positive electrode plates and six unchemical negative electrode plates housed in the bag-shaped separator were alternately laminated so that the ribs of the separator were in contact with the positive electrode plates. Subsequently, the ears of the plates having the same polarity were welded to each other by a cast-on-strap (COS) method to prepare a group of plates. A 2V single cell battery (corresponding to a B19 size single cell specified in JIS D 5301) was assembled by inserting the electrode plate group into the battery case. Dilute sulfuric acid (electrolyte solution) having a specific gravity of 1.23 in which aluminum sulfate anhydride was dissolved was injected into this battery so that the aluminum ion concentration became 0.08 mol / L. Then, it was formed in a water tank at 50 ° C. at an energizing current of 10 A for 16 hours, and the specific gravity of the electrolytic solution after the formation was adjusted to 1.28 to obtain a lead storage battery.

[Total amount of oxygen and silicon in the separator]
First, the separator before assembling the battery was cut to expose the cross section by an ion milling device E-3500 (manufactured by Hitachi High-Technologies Corporation, trade name). Next, EDX analysis of the cross section of the separator was performed using a scanning electron microscope (trade name: JSM-6010LA, manufactured by JEOL Ltd.). Mapping analysis was performed at a magnification of 300 times, and after the measurement, the separator portion was selected, the abundances of carbon, oxygen and silicon were quantified, and converted into the mass of each element. The total amount (mass%) of the masses of oxygen and silicon in the separator was calculated based on the total masses of the obtained carbon, oxygen and silicon. The conditions for mapping analysis are: acceleration voltage is 15 kV, spot size is 72, pressure is 35 Pa in low vacuum mode, duel time is 1 millisecond, process time is T4, number of pixels is 512 x 384, and the number of integrations is 5 times. And said. Table 1 shows the quantitative results of each element.

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

The specific surface areas of the positive electrode material and the negative electrode material after chemical conversion were calculated according to the BET method by measuring the amount of nitrogen gas adsorbed at the liquid nitrogen temperature while cooling the measurement sample prepared above with liquid nitrogen. The measurement conditions were as follows. As a result of the measurement in this manner, the specific surface area of the positive electrode material was 5 m ² / g, and the specific surface area of the negative electrode material was 0.6 m ² / g.

{Measurement conditions for specific surface area}
Equipment: HM-2201FS (manufactured by Macsorb)
Degassing time: 10 minutes at 130 ° C Cooling: 4 minutes with liquid nitrogen Adsorption gas flow rate: 25 mL / min

(Examples 2 and 3)
A lead-acid battery was produced by the same method as in Example 1 except that dilute sulfuric acid having a specific gravity of 1.280 prepared so that the aluminum ion concentration became the value shown in Table 1 was used as the electrolytic solution.

(Example 4)
As the electrolytic solution, dilute sulfuric acid having a specific gravity of 1.280 in which aluminum sulfate anhydride and sodium sulfate were dissolved was used so that the aluminum ion concentration was 0.14 mol / L and the sodium ion concentration was 0.06 mol / L. A lead-acid battery was produced by the same method as in Example 1 except for the above.

(Comparative Example 1)
A lead-acid battery was produced by the same method as in Example 1 except that dilute sulfuric acid having a specific gravity of 1.280 containing no aluminum ions was used as the electrolytic solution.

(Comparative Example 2)
A lead-acid battery was produced by the same method as in Example 1 except that dilute sulfuric acid having a specific gravity of 1.280 in which sodium sulfate was dissolved was used as the electrolytic solution so that the sodium ion concentration was 0.1 mol / L. did.

<Evaluation of battery characteristics>
The charge acceptance performance and the permeation short circuit of the lead-acid battery were evaluated as follows. The results are shown in Table 1. In addition, "-" in Table 1 means that aluminum sulfate or sodium sulfate was not blended.

(Charge acceptance performance)
The produced lead-acid battery was discharged at an atmospheric temperature of 25 ° C. at 5.6 A for 30 minutes at a constant current and left to stand for 6 hours. Then, the lead-acid battery was charged at a constant voltage of 2.33 V for 60 seconds under a current limit of 100 A, and the current value was measured 5 seconds after the start of charging. The charge acceptance performance was relatively evaluated with the measurement result of Comparative Example 1 as 100.

(Penetration short circuit)
The produced lead-acid battery was discharged at a constant current of 1.4 A at an ambient temperature of 25 ° C. Next, after discharging until the cell voltage reached 1.75 V, the lead-acid battery was connected to a 10 W lamp at an ambient temperature of 40 ° C. and left in an over-discharged state for 5 days. Then, it was charged at 25 ° C. under a current limit of 25 A at a cell voltage of 2.33 V for 8 hours. By repeating the above discharge and charging, a short circuit occurs when the current fluctuates (current fluctuation of 0.3A or more) or the terminal current (current about 8 hours after the start of charging) remains high (3A or more) during charging. The number of repetitions until the short circuit was measured. The permeation short circuit was relatively evaluated with the measurement result of Comparative Example 1 as 100.

In the examples, it was confirmed that the evaluation results of the permeation short circuit and the charge acceptance performance were superior to those of Comparative Examples 1 and 2. In Comparative Example 2, although the electrolytic solution contains sodium ions, it does not contain aluminum ions. Therefore, it is presumed that the result of the permeation short-circuit evaluation was not excellent because aluminum compounds such as aluminum hydroxide did not precipitate.

10, 20 ... Separator, 10a ... One side, 10b ... Other side, 11 ... Base part, 12 ... Rib, 13 ... Mini rib, 14, 14a, 14b ... Electrode, 22 ... Mechanical seal part, A ... Bottom width of rib , B ... Rib top base width, H ... Rib height, T ... Base thickness.

Claims (8)

A positive electrode and a negative electrode facing each other via a separator, and an electrolytic solution are provided.
The separator has a convex rib, a base portion supporting the rib, and contains polyolefin and silica.
In the elemental analysis by the energy dispersion type X-ray spectroscopy, the total mass of oxygen and silicon in the separator is 30 to 80% by mass based on the total mass of carbon, oxygen and silicon.
The height H of the rib is 1 mm or less,
The thickness T of the base portion is 0.05 mm or more, and the thickness T is 0.05 mm or more.
The electrolyte contains aluminum ions
A lead-acid battery having a concentration of the aluminum ions in the electrolytic solution of 0.01 to 0.3 mol / L. A positive electrode and a negative electrode facing each other via a separator, and an electrolytic solution are provided.
The separator has a convex rib, a base portion supporting the rib, and contains polyolefin and silica.
In the elemental analysis by the energy dispersion type X-ray spectroscopy, the total mass of oxygen and silicon in the separator is 30 to 80% by mass based on the total mass of carbon, oxygen and silicon.
The ratio H / T of the height H of the rib to the thickness T of the base portion is 6 or less.
The thickness T of the base portion is 0.05 mm or more, and the thickness T is 0.05 mm or more.
The electrolyte contains aluminum ions
A lead-acid battery having a concentration of the aluminum ions in the electrolytic solution of 0.01 to 0.3 mol / L. A positive electrode and a negative electrode facing each other via a separator, and an electrolytic solution are provided.
The separator has a convex rib, a base portion supporting the rib, and contains polyolefin and silica.
In the elemental analysis by the energy dispersion type X-ray spectroscopy, the total mass of oxygen and silicon in the separator is 30 to 80% by mass based on the total mass of carbon, oxygen and silicon.
The rib spacing is 3 to 15 mm.
The thickness T of the base portion is 0.05 mm or more, and the thickness T is 0.05 mm or more.
The electrolyte contains aluminum ions
A lead-acid battery having a concentration of the aluminum ions in the electrolytic solution of 0.01 to 0.3 mol / L. A positive electrode and a negative electrode facing each other via a separator, and an electrolytic solution are provided.
The separator has a convex rib and a base portion that supports the rib, and contains polyolefin and silica particles.
The specific surface area of the silica particles is 100 to 400 m. ² / G
The height H of the rib is 1 mm or less,
The thickness T of the base portion is 0.05 mm or more, and the thickness T is 0.05 mm or more.
The electrolyte contains aluminum ions
A lead-acid battery having a concentration of the aluminum ions in the electrolytic solution of 0.01 to 0.3 mol / L. A positive electrode and a negative electrode facing each other via a separator, and an electrolytic solution are provided.
The separator has a convex rib and a base portion that supports the rib, and contains polyolefin and silica particles.
The specific surface area of the silica particles is 100 to 400 m. ² / G
The ratio H / T of the height H of the rib to the thickness T of the base portion is 6 or less.
The thickness T of the base portion is 0.05 mm or more, and the thickness T is 0.05 mm or more.
The electrolyte contains aluminum ions
A lead-acid battery having a concentration of the aluminum ions in the electrolytic solution of 0.01 to 0.3 mol / L. A positive electrode and a negative electrode facing each other via a separator, and an electrolytic solution are provided.
The separator has a convex rib and a base portion that supports the rib, and contains polyolefin and silica particles.
The specific surface area of the silica particles is 100 to 400 m. ² / G
The rib spacing is 3 to 15 mm.
The thickness T of the base portion is 0.05 mm or more, and the thickness T is 0.05 mm or more.
The electrolyte contains aluminum ions
A lead-acid battery having a concentration of the aluminum ions in the electrolytic solution of 0.01 to 0.3 mol / L. The lead-acid battery according to any one of claims 1 to 6 , wherein the separator has a bag shape that encloses at least one electrode of a positive electrode and a negative electrode. The negative electrode has a current collector and a negative electrode material held by the current collector.
The lead-acid battery according to any one of claims 1 to 7 , wherein the negative electrode material contains an active material and a resin having at least one selected from the group consisting of a sulfone group and a sulfonic acid base.

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