WO2016204049A1

WO2016204049A1 - Lead storage cell

Info

Publication number: WO2016204049A1
Application number: PCT/JP2016/067119
Authority: WO
Inventors: 近藤　隆文; 柴原　敏夫; 博紀平野; 和也丸山
Original assignee: 日立化成株式会社
Priority date: 2015-06-18
Filing date: 2016-06-08
Publication date: 2016-12-22
Also published as: JP6338020B2; JPWO2016204049A1; JP2020017547A; JP2018116943A; JP6614273B2; JP6849040B2

Abstract

A lead storage cell provided with a positive electrode and a negative electrode that face each other across a separator 10, and an electrolyte. The separator 10 contains a polyolefin and silica. The positive electrode has a positive electrode collector and a positive electrode member held by the positive electrode collector. The negative electrode has a negative electrode collector and a negative electrode member held by the negative electrode collector. The electrolyte contains aluminum ions. The mass ratio of the chemically converted positive electrode member relative to the chemically converted negative electrode member is 1.05 or higher.

Description

Lead acid battery

The present invention relates to a lead storage battery.

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

In ISS cars, the number of engine starts increases, so the large current discharge of the lead storage battery is repeated. Further, in the ISS car and the power generation control car, the amount of power generated by the alternator is reduced, and the lead storage battery is charged intermittently, so that the charge is insufficient.

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

Incidentally, the lead storage battery has a structure in which, for example, a positive electrode (positive electrode plate or the like), a negative electrode (negative electrode plate or the like), and a synthetic resin bag-like separator that separates both electrodes are laminated. As the separator, there is known a microporous film with ribs formed by projecting main ribs for electrode plate contact on one side of a flat sheet, which is mainly formed of polyolefin or the like that can be easily integrated into a bag and processed with a bag. It has been. This separator made of a microporous film with ribs is usually designed such that the surface on which the main ribs for electrode plate abutment are in contact with the positive electrode plate. Further, the surface opposite to the surface on which the electrode plate contact main rib protrudes is a flat surface on which no rib is provided, and is designed to contact the negative electrode plate.

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

Also, in lead-acid batteries, during repeated charging and discharging, water is generated during discharging and sulfuric acid is generated during charging. Since sulfuric acid has a higher specific gravity than water and tends to settle at the lower part, a stratification phenomenon occurs in which the electrolyte (sulfuric acid) concentration differs between the upper part and the lower part of the battery. Since the conventional engine vehicle is overcharged during running, stratification is alleviated by the stirring action of the electrolyte solution by oxygen gas and hydrogen gas generated from the positive electrode and the negative electrode at this time. However, under PSOC, the state of insufficient charging continues, so that the stirring action of the electrolyte solution by oxygen gas and hydrogen gas hardly occurs, and stratification tends to occur. When stratification occurs, the electrolyte concentration in the upper part of the battery decreases, so the amount of lead sulfate dissolved in the upper part of the battery increases, and an osmotic short circuit is likely to occur.

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

JP2013-211115A

By the way, according to the study by the present inventors, when silica is used as the inorganic powder contained in the separator, the penetration short circuit is likely to occur. For example, in the technique described in Patent Document 1, the penetration short circuit is suppressed. Has been found to be not sufficient. Therefore, in recent years, it has been required for lead storage batteries to further improve the short-circuit suppressing effect 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-acid battery that has an excellent short-circuit suppressing effect even when a separator containing silica is used.

A lead storage battery according to the present invention includes a positive electrode and a negative electrode facing each other via a separator, and an electrolyte solution, the separator includes polyolefin and silica, and the positive electrode is held by the positive electrode current collector and the positive electrode current collector. A negative electrode current collector, and a negative electrode material held by the negative electrode current collector, the electrolytic solution contains aluminum ions, and after the formation of the negative electrode material after the formation The mass ratio of the positive electrode material is 1.05 or more.

The lead storage battery according to the present invention is excellent in the short-circuit suppressing effect even when a separator containing silica is used by having the above-described configuration. Moreover, according to the lead acid battery which concerns on this invention, it is possible to obtain the outstanding battery characteristic, suppressing a short circuit, for example, the outstanding charge acceptance property and ISS cycle characteristic can be obtained. Therefore, especially after a certain amount of charge / discharge is repeated from the initial state and the active material is sufficiently activated, the state of charge (SOC), which tends to be low in ISS cars, micro hybrid cars, etc., is set to an appropriate level. Can be maintained. Moreover, according to the lead acid battery which concerns on this invention, the outstanding charge acceptance property and ISS cycle characteristic, and other outstanding battery characteristics (a capacity | capacitance, discharge characteristic, etc.) can be made compatible.

Moreover, according to the lead acid battery which concerns on this invention, it can suppress that the lifetime of the lead acid battery used under PSOC becomes short. Regarding the reason why the life of lead-acid batteries used under PSOC is shortened, if charging and discharging are repeated in a state where charging is insufficient, lead sulfate produced on the negative electrode (negative electrode plate, etc.) becomes coarse during discharge. This is thought to be because lead sulfate is difficult to return to the spongy metallic lead that is the 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, it is possible to improve the separator strength while further improving the short-circuit suppressing effect.

The concentration of aluminum ions in the electrolytic solution is preferably 0.01 to 0.3 mol / L. In this case, it is possible to further improve battery characteristics such as charge acceptability while further improving the short-circuit suppressing effect.

It is preferable that the electrolytic solution further contains sodium ions. In this case, the 5-hour capacity cycle characteristics can be further improved.

The mass ratio of the positive electrode material after conversion to the negative electrode material after conversion is preferably 1.05 to 1.60, and more preferably 1.05 to 1.50. In this case, the short circuit can be more effectively suppressed and the charge acceptability and the low temperature high rate discharge performance are further improved.

The specific surface area of the positive electrode material is preferably 3 m ² / g or more. In this case, the charge acceptability is further improved.

The specific surface area of the negative electrode material is preferably 0.4 m ² / g or more. In this case, the reactivity between the electrolytic solution and the negative electrode active material can be increased.

In the lead-acid battery according to the present invention, the separator is a long separator having a first rib, a second rib, and a base portion, and the base portion includes the first rib and the first rib. 2 ribs, and the first rib and the second rib extend in the longitudinal direction of the separator, and both end portions in the short direction of the separator each support the second rib. There may be an aspect in which 10 to 40 are included and the region between the both end portions includes the first rib.

According to the present invention, it is possible to provide a lead storage battery that is excellent in the effect of suppressing a short circuit even when a separator containing silica is used. Moreover, according to the lead acid battery which concerns on this invention, the outstanding battery characteristic (for example, charge acceptance property and ISS cycle characteristic) can be acquired, suppressing a short circuit. Furthermore, according to the lead storage battery of the present invention, it is possible to achieve both excellent charge acceptability and ISS cycle characteristics and other excellent battery characteristics (capacity, discharge characteristics, etc.). The lead acid battery according to the present invention can be suitably used in an automobile such as an ISS car and a micro hybrid car as a liquid lead acid battery in which charging is intermittently performed and high rate discharge is performed under PSOC. ADVANTAGE OF THE INVENTION According to this invention, the application to the micro hybrid vehicle of a lead storage battery can be provided. ADVANTAGE OF THE INVENTION According to this invention, the application to the ISS vehicle of a lead storage battery can be provided.

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

Hereinafter, embodiments of the present invention will be described in detail. In addition, since specific gravity changes with temperature, in this specification, it defines as specific gravity converted at 20 degreeC. Further, in this specification, “silica” means silicon dioxide (SiO ₂ ) or a general term for substances composed of silicon dioxide.

<Lead battery>
The lead storage 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) that face each other with a separator interposed therebetween, and an electrolyte solution (such as sulfuric acid). The liquid contains aluminum ions.

The lead storage battery according to this embodiment includes, for example, a battery case, an electrode (electrode plate or the like), an electrolytic solution (sulfuric acid or the like), and a separator, and has a positive electrode and a negative electrode as electrodes. The electrode, the electrolytic solution, and the separator are accommodated in the battery case. Examples of the lead storage battery according to this embodiment include a liquid lead storage battery, a control valve type lead storage battery, and the like, and a liquid lead storage battery is preferable.

The positive electrode and the negative electrode constitute an electrode group (electrode plate group or the like) by being laminated via a separator. The positive electrode has a positive electrode current collector and a positive electrode material held by the positive electrode current collector. The negative electrode has a negative electrode current collector and a negative electrode material held by the negative electrode 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 unformed, the electrode materials (unformed positive electrode material and unformed negative electrode material) contain the raw materials and the like. The current collector constitutes a conductive path for current from the electrode material. As a basic configuration of the lead storage battery, the same configuration as that of a conventional lead storage battery can be used.

The mass ratio of the positive electrode material after conversion to the negative electrode material after conversion (positive electrode material / negative electrode material) is 1.05 or more. A short circuit can be effectively suppressed because the mass ratio is 1.05 or more. The mass ratio is more preferably 1.10 or more, and even more preferably 1.13 or more, from the viewpoint of more effectively suppressing a short circuit. The mass ratio is preferably 1.60 or less, more preferably 1.55 or less, still more preferably 1.50 or less, and particularly preferably 1.40 or less from the viewpoint of further excellent charge acceptance and low-temperature high-rate discharge performance. 1.30 or less is very preferable, 1.20 or less is very preferable, and 1.17 or less is even more preferable. From these viewpoints, the mass ratio is preferably 1.05 to 1.60, more preferably 1.05 to 1.55, still more preferably 1.05 to 1.50, and 1.05 to 1.40. Particularly preferred is 1.05 to 1.30, very preferably 1.05 to 1.20, very preferably 1.05 to 1.17, even more preferably 1.10 to 1.17, .13 to 1.17 are particularly preferred.

The present inventors infer the reason why the occurrence of a short circuit can be suppressed when the mass ratio of the positive electrode material after conversion to the negative electrode material after conversion is within the above range. In an overdischarged state due to a minute current, discharge is possible until the remaining rate of the positive electrode or negative electrode active material is about 25%. When the mass ratio of the positive electrode material / negative electrode material is less than 1.05 (for example, 1.00 or more and less than 1.05, when the amount of the active material of the negative electrode is larger than the amount of the active material of the positive electrode) By increasing the capacity that can be discharged, the amount of sulfuric acid used as the electrolytic solution increases, and the specific gravity of sulfuric acid in the electrolytic solution decreases to a value close to that of water. On the other hand, when the mass ratio of the positive electrode material / negative electrode material is 1.05 or more (when the amount of the active material of the negative electrode is small with respect to the amount of the active material of the positive electrode), the capacity that the negative electrode can discharge becomes small. The discharge limit is reached earlier than when the amount of the negative electrode material is large, the consumption amount of sulfuric acid used as the electrolytic solution is reduced, and the decrease in the sulfuric acid specific gravity of the electrolytic solution is reduced. As a result, since dissolution of lead sulfate in the active material into the electrolytic solution is suppressed, it is presumed that an infiltration short circuit can be suppressed.

(Separator)
The separator prevents electrical connection between the positive electrode and the negative electrode and allows sulfate ions in the electrolytic solution to pass therethrough. The separator includes polyolefin and silica. The separator is preferably made 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 such as ethylene, propylene, butene, methylpentene, 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 good productivity.

The weight average molecular weight of the polyolefin is preferably 500,000 or more and more preferably 1,000,000 or more from the viewpoint of excellent mechanical strength of the separator. Although there is no restriction | limiting in particular in the upper limit of a weight average molecular weight, From a practical viewpoint, 5 million or less is preferable. In addition, the weight average molecular weight of polyolefin can be measured, for example with a high temperature GPC apparatus, using toluene or xylene as an eluent.

In the present embodiment, it is preferable to use silica particles as silica. As the silica particles, particles having a fine particle diameter and having a pore structure inside and / or 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 (densified) and complicated to further improve the short-circuit resistance, and to increase the electrolyte solution holding power. By providing a hydrophilic group (such as —OH), the hydrophilicity of the separator can be further increased. Moreover, it is preferable that the specific surface area of a silica particle is 400 m < ² > / g or less from a viewpoint that a silica particle can disperse | distribute uniformly in a 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 by, for example, the BET method.

The number of silica particles having a particle size (longest 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 × 30 μm × 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 from the viewpoint of further improving the short-circuit suppressing effect and improving the separator strength. The following ranges are preferred based on the total mass of carbon, oxygen and silicon. The total of the masses of oxygen and silicon is preferably 30% by mass or more, more preferably 40% by mass or more, and further preferably 50% by mass or more. The total mass of oxygen and silicon may be 55% by mass or more, or 60% by mass or more. The total of the masses of oxygen and silicon is preferably 80% by mass or less, more preferably 75% by mass or less, and 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 of the masses of oxygen and silicon is preferably 30 to 80% by mass, more preferably 40 to 75% by mass, and still more preferably 50 to 70% by mass. The total of the masses of oxygen and silicon may be 55 to 75% by mass or 60 to 65% by mass.

The masses of carbon, oxygen, and silicon in the separator can be obtained, for example, by analyzing the cross section of the separator by energy dispersive X-ray spectroscopy (EDX). That is, the total mass of oxygen and silicon is preferably 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 this embodiment can be obtained, for example, by melt-kneading a raw material composition mainly composed of polyolefin, silica, and a plasticizer to form a sheet-like material having a predetermined shape.

As the plasticizer, for example, mineral oil such as industrial lubricating oil made of saturated hydrocarbon (paraffin); higher alcohol such as stearyl alcohol; ester plasticizer such as dioctyl phthalate can be used. Among these, mineral oil is preferable because it can be easily reused. The plasticizer is preferably blended in the raw material composition mainly composed of polyolefin, silica and 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 a method such as extraction and removal using a solvent after melt-kneading a raw material composition mainly composed of polyolefin, silica, and plasticizer to form a sheet-like material having a predetermined shape. By removing the plasticizer, it can be made porous. However, in the lead-acid battery separator, the oxidation resistance can be improved by adding 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 organic solvent such as hexane, heptane, octane, nonane, decane and the like can be used.

Other separators include surfactants (hydrophilic agents), antioxidants, UV absorbers, weathering agents, lubricants, antibacterial agents, antifungal agents, pigments, dyes, colorants, antifogging agents, as necessary. You may contain additives, such as a matting agent, in the range which does not impair the objective and effect of this invention.

The separator preferably has a first rib and a base portion that supports the first rib, and more preferably has a second rib supported by the base portion. The first rib and the second rib are, for example, convex. The separator is long, for example, and the first rib and the second rib extend, for example, in the longitudinal direction of the separator. The height and / or width of the first rib is larger than, for example, the second rib. The lead-acid battery according to the present embodiment has a first region including a first rib and a second region including a second rib, and a short direction of the separator (a direction perpendicular to the longitudinal direction; width). Each end portion (one end portion and the other end portion; two second regions) in the direction) includes a second rib, and a region (first region) between the both end portions is a first rib. It is also possible to include this. Hereinafter, one aspect of the separator of the present embodiment will be described with reference to FIGS.

FIG. 1 (a) is a front view showing a separator, and FIG. 1 (b) 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 base portion 11, a plurality of convex ribs (first ribs) 12, and a plurality of convex mini ribs (second ribs) 13. ing. The base portion 11 supports the rib 12 and the mini rib 13. A plurality of ribs 12 (multiple ribs) are arranged in the center (first region) in the width direction of the separator 10 so as to extend in the longitudinal direction of the separator 10. The plurality of ribs 12 are disposed substantially parallel to each other on the one surface 10 a of the separator 10. The interval between the ribs 12 is, for example, 3 to 15 mm. One end in the height direction of the rib 12 is integrated with the base portion 11, and the other end in the height direction of the rib 12 is in contact with one electrode 14a of the positive electrode and the negative electrode (see FIG. 2). The base portion 11 faces the electrode 14 a in the height direction of the rib 12. Ribs are not disposed 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 of (many) mini-ribs 13 are arranged so as to extend in the longitudinal direction of the separator 10 on both sides (both ends, two second regions) 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 when the lead storage battery vibrates in the lateral direction.

The number of the mini-ribs 13 is preferably 10 or more from the viewpoint that the end of the separator is less likely to be wrinkled when the separator is wound, and that the strength for preventing a short circuit is easily improved. More than this is more preferable. The number of mini-ribs 13 is preferably 40 or less from the viewpoint of easily forming the separator in a bag shape. From these viewpoints, the number of the mini-ribs 13 is preferably 10 to 40, more preferably 20 to 40. When miniribs are arranged at both ends in the short direction of the separator, the number of miniribs 13 is, for example, the number arranged at each of both ends.

The height, width, and interval of the mini-ribs 13 are preferably smaller than the ribs 12. The cross-sectional shape of the minirib 13 may be the same as or different from 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 disposed 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, and 0.25 mm from the viewpoint of obtaining further excellent charge acceptability and discharge characteristics. Is particularly preferably 0.225 mm or less, and very preferably 0.2 mm or less. Although there is no restriction | limiting in particular in the minimum of the thickness T of the base part 11, 0.05 mm or more is preferable and 0.1 mm or more is more preferable from a viewpoint which is further excellent in the suppression effect of a short circuit.

The upper limit of the height H of the rib 12 (the height in the facing direction of the base portion 11 and the electrode 14) H is preferably 1 mm or less, more preferably 0.9 mm or less, from the viewpoint of obtaining further excellent charge acceptance. 8 mm or less is further preferable, and 0.6 mm or less is particularly 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, and still more preferably 0.5 mm or more, from the viewpoint of suppressing oxidative deterioration at the positive electrode. From these viewpoints, the height H of the rib 12 is preferably 0.3 to 1 mm, more preferably 0.3 to 0.9 mm, still more preferably 0.3 to 0.8 mm, and 0.4 to 0.8 mm. Is particularly preferable, and 0.5 to 0.6 mm is very preferable.

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, a portion that does not contact the electrode (for example, the positive electrode) can be sufficiently secured, so that it is estimated that the oxidation resistance of the separator is improved. The lower limit of the ratio H / T is more preferably 2.3 or more, and even more 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 a further excellent short-circuit suppressing effect. If the ratio H / T is 6 or less, the distance between the positive electrode and the negative electrode is sufficient, and it is estimated that the short circuit is further suppressed. Further, when the ratio H / T is 6 or less, it is presumed that the battery characteristics such as charge acceptability are favorably maintained without damaging the ribs when the lead storage battery is assembled. The upper limit of the ratio H / T is more preferably 5 or less, further preferably 4 or less, particularly preferably 3.7 or less, from the viewpoint of further improving the short-circuit suppressing effect and from the viewpoint of excellent rib shape retention. .5 or less is very preferable, and 3 or less is very preferable.

In view of the above, the ratio H / T is preferably 2 to 6, more preferably 2.3 to 5, further preferably 2.3 to 4, particularly preferably 2.3 to 3.7, and 2.3 to 3 .5 is very preferable, and 2.5 to 3 is very preferable.

The upper base width B of the rib 12 (see FIG. 1B) is preferably 0.1 mm or more, more preferably 0.2 mm or more, and more preferably 0.3 mm or more from the viewpoint of excellent rib shape retention and oxidation resistance. Is more preferable, and 0.35 mm or more is particularly preferable. From the same viewpoint, the upper base width B of the rib 12 is preferably 2 mm or less, more preferably 1 mm or less, still more preferably 0.8 mm or less, and particularly preferably 0.5 mm or less. From these viewpoints, the upper base width B of the rib 12 is preferably 0.1 to 2 mm, more preferably 0.2 to 2 mm, still more preferably 0.3 to 2 mm, particularly preferably 0.35 to 2 mm, 0 .35 to 1 mm is very preferable, 0.35 to 0.8 mm is very preferable, and 0.35 to 0.5 mm is even more preferable. The upper base width B of the rib 12 may be 0.2 to 1 mm, or may be 0.2 to 0.8 mm.

The bottom bottom width A of the rib is preferably 0.2 mm or more, more preferably 0.3 mm or more, still more preferably 0.4 mm or more, particularly preferably 0.5 mm or more, from the viewpoint of excellent rib shape retention. .7 mm or more is very preferable. From the same viewpoint, the lower bottom width A of the rib is preferably 4 mm or less, more preferably 2 mm or less, and still more preferably 1 mm or less. From these viewpoints, the bottom bottom width A of the rib is preferably 0.2 to 4 mm, more preferably 0.3 to 2 mm, still more preferably 0.4 to 1 mm, particularly preferably 0.5 to 1 mm. 7 to 1 mm is very preferable.

The ratio B / A of the upper base width B to the lower base width A is preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.3 or more, from the viewpoint of excellent rib shape retention. .4 or more is particularly preferable, and 0.45 or more is very preferable. From the same viewpoint, the ratio B / A is preferably 1 or less, more preferably 0.8 or less, still more preferably 0.6 or less, and particularly preferably 0.55 or less. From these viewpoints, the ratio B / A is preferably 0.1 to 1, more preferably 0.2 to 0.8, still more preferably 0.3 to 0.6, and particularly preferably 0.4 to 0.55. 0.45 to 0.55 is particularly preferable.

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

The separator 10 may be a microporous polyethylene sheet; a glass fiber and acid-resistant paper bonded together. The separator 10 is preferably cut according to the length of the negative electrode (negative electrode plate or the like) in the step of laminating the electrodes (electrode plate or the like). Further, the cut separator 10 may be folded in two and wrapping the negative electrode by crimping both sides.

FIG. 3 is a view showing a bag-like separator 20 and an electrode (for example, a negative electrode) 14 accommodated in the separator 20. As shown to Fig.1 (a), the separator 10 used for preparation of the separator 20 is formed in the elongate sheet form, for example. The separator 20 shown in FIG. 3 is obtained by cutting the separator 10 into an appropriate length, folding it in the longitudinal direction of the separator 10 and placing the electrodes 14 on the inside thereof, and superimposing them on both sides. It is obtained by welding (for example, reference numeral 22 in FIG. 3 indicates a mechanical seal portion).

(Electrolyte)
The electrolytic solution of the lead storage battery according to the present embodiment contains aluminum ions. When 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 when the electrolyte contains 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 be in an alkaline atmosphere, and when aluminum ions are not present in the electrolytic solution, silica is easily dissolved when it becomes alkaline. When silica is dissolved, it is presumed that a short circuit is likely to occur because the separator contracts and the thickness of the separator decreases. Further, when the pH increases due to the consumption of hydrogen ions due to the discharge reaction of the positive electrode (the pH shifts to the alkali side), the solubility of lead sulfate increases at the positive electrode, and the solubility and the pH decrease during charging (the pH decreases). From the difference in the solubility of lead sulfate when shifting to the acidic side), it is presumed that lead sulfate precipitates are likely to be generated 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 deposited inside the separator during discharge. Since the dissolution of silica is suppressed by precipitation of an aluminum compound such as aluminum hydroxide in this manner, the thickness of the separator can be maintained. In addition, since the pH of the electrolytic solution is increased by the precipitation reaction of an aluminum compound such as aluminum hydroxide (the pH is shifted to the alkali side), an increase in the solubility of lead sulfate can be suppressed. By these, it is estimated that a short circuit can be suppressed because aluminum ion exists in electrolyte solution.

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 improving the short-circuit suppressing effect and further improving battery characteristics such as charge acceptance. 0.02 mol / L or more is more preferable, and 0.05 mol / L or more is more preferable. From the same viewpoint, 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, and 0 .14 mol / L or more may be sufficient, and 0.15 mol / L or more may be sufficient. The aluminum ion concentration of the electrolytic solution is preferably 0.3 mol / L or less on the basis of the total amount of the electrolytic solution from the viewpoint of further improving the short-circuit suppressing effect and further improving the charge acceptability and the ISS cycle characteristics. 0.25 mol / L or less is more preferable, and 0.2 mol / L or less is still more preferable. From these viewpoints, the aluminum ion concentration of the electrolytic solution is preferably from 0.01 to 0.3 mol / L, more preferably from 0.02 to 0.25 mol / L, based on the total amount of the electrolytic solution, from 0.05 to 0.2 mol / L is more preferable. From the same viewpoint, 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, 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 spectroscopy (high frequency inductively coupled plasma emission spectroscopy).

Regarding the mechanism that further improves the short-circuit suppressing effect when the aluminum ion concentration of the electrolytic solution is within the predetermined range, it is presumed as described above regarding the use of aluminum ions. The details of the mechanism for improving the charge acceptability are not clear, but are presumed as follows. That is, when the aluminum ion concentration is within the predetermined range, the solubility of the crystalline lead sulfate, which is a discharge product, in the electrolytic solution increases under any low SOC, or due to the high ion conductivity of aluminum ions. Since the diffusibility of the electrolytic solution into the electrode active material is improved, it is estimated 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 ions, potassium ions, phosphate ions, etc.), and preferably contains sodium ions. When the electrolytic solution contains sodium ions, the 5-hour capacity cycle characteristics tend to be further improved.

In lead-acid batteries, there is a phenomenon called PCL (Premium Capacity Loss), in which the battery capacity decreases early. This is a phenomenon in which the partial discharge progresses at the interface between the current collector and the active material and the capacity is quickly reduced. PCL can be evaluated by 5-hour capacity cycle characteristics.

When the electrolytic solution contains sodium ions, the sodium ion concentration is preferably 0.01 mol / L or more, based on the total amount of the electrolytic solution, and preferably 0.02 mol / L or more from the viewpoint of further improving the 5-hour capacity cycle characteristics. More preferred is 0.03 mol / L or more. The sodium ion concentration of the electrolytic solution is preferably 0.1 mol / L or less, based on the total amount of the electrolytic solution, from the viewpoint of further improving the 5-hour capacity cycle characteristics, the charge acceptability and the ISS cycle characteristics, and is preferably 0.08 mol / L. L or less is more preferable, and 0.06 mol / L or less is still more preferable. From these viewpoints, the sodium ion concentration is preferably 0.01 to 0.1 mol / L, more preferably 0.02 to 0.08 mol / L, and more preferably 0.03 to 0.06 mol, based on the total amount of the electrolytic solution. / L is more preferable. The sodium ion concentration of the electrolytic solution can be measured, for example, by ICP emission spectroscopy (high frequency inductively coupled plasma emission spectroscopy).

(Positive electrode 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 unformed positive electrode active material and then forming an unformed 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 ). There is no restriction | limiting in particular as a raw material of a positive electrode active material, For example, lead powder is mentioned. As the lead powder, for example, lead powder manufactured by a ball mill type lead powder manufacturing machine or a barton pot type lead powder manufacturing machine (in the ball mill type lead powder manufacturing machine, a mixture of powder of main component PbO and scale-like metal lead) ). Red lead as a raw material of the positive electrode active material _(Pb 3 _{O 4)} may be used. The unformed positive electrode material preferably contains an unformed positive electrode active material containing tribasic lead sulfate as a main component.

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

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 acceptance, ISS cycle characteristics, etc.) 97 mass% or more is more preferable, and 99 mass% or more is still more preferable. 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 material, 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, and carbon fibers.

[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, and still more preferably 5 m ² / g or more from the viewpoint of further excellent charge acceptance. 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, is ^12m 2 / g or less Further 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 unformed 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 adsorption amount and the area occupied by the inert gas. This is a general method for measuring the surface area. Specifically, it is measured based on the following BET equation.

Relationship of the following formula (1), _P / P _o is satisfied be in the range of 0.05-0.35. In addition, in Formula (1), the detail of each code | symbol is as follows.
P: Adsorption equilibrium pressure when in an adsorption equilibrium state at a constant temperature P _o : Saturated vapor pressure at the adsorption temperature V: Adsorption amount at the adsorption equilibrium pressure P V _m : Monomolecular layer adsorption amount (a gas molecule is a single molecule on a solid surface) Adsorption amount when layer is formed)
C: BET constant (parameter relating to the interaction between the solid surface and the adsorbent)

By transforming equation (1) (dividing the numerator denominator on the left side by P), the following equation (2) is obtained. In the specific surface area meter used for the measurement, gas molecules having a known adsorption occupation area are adsorbed on the sample, and the relationship between the adsorption amount (V) and the relative pressure (P / P _o ) 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 formula (3) is derived from the formula (2). Assuming that the intercept is i, the intercept i and the gradient s are as shown in the following formula (4) and the following formula (5), respectively.

When Expression (4) and Expression (5) are modified, the following Expression (6) and Expression (7) are obtained, respectively, and the following Expression (8) for obtaining the monomolecular layer adsorption amount V _m is obtained. That is, when the adsorption amount V at a certain relative pressure P / _Po is measured at several points and the slope and intercept of the plot are obtained, the monomolecular layer adsorption amount V _m is obtained.

The total surface area S _total (m ² ) of the sample is obtained by the following formula (9), and the specific surface area S (m ² / g) is obtained by the following formula (10) from the total surface area S _total . In the formula (9), N denotes the Avogadro's _{number, A CS} shows the adsorption cross sectional area ^{(m 2),} M indicates the molecular weight. Moreover, in Formula (10), w shows a 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 area where sulfuric acid enters the pores (holes) in the positive electrode material increases and the capacity tends to increase. Although there is no restriction | limiting in particular in the upper limit of the porosity of a positive electrode material, 70 volume% or less is preferable from a viewpoint that the amount of sulfuric acid impregnation to the void | hole part in a positive electrode material is moderate, and can maintain the bonding force of active materials favorably. . The upper limit of the porosity is more preferably 60% by volume or less from a practical viewpoint. 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 (ratio based on volume) obtained from mercury porosimeter measurement. The porosity of the positive electrode material can be adjusted by, for example, the amount of dilute sulfuric acid added when producing the positive electrode material paste.

(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 chemical conversion of an unformed negative electrode active material after obtaining an unformed negative electrode active material by aging and drying a negative electrode material paste containing a raw material of the negative electrode active material. Examples of the negative electrode active material after chemical conversion include spongy lead. The spongy lead tends to react with sulfuric acid in the electrolyte and gradually change to lead sulfate (PbSO ₄ ). Examples of the raw material for the negative electrode active material include lead powder. As the lead powder, for example, lead powder manufactured by a ball mill type lead powder manufacturing machine or a barton pot type lead powder manufacturing machine (in the ball mill type lead powder manufacturing machine, a mixture of powder of main component PbO and scale-like metal lead) ). The unformed negative electrode active material is composed of, for example, basic lead sulfate, metallic lead, and a lower oxide.

The average particle diameter of the negative electrode active material is preferably 0.3 μm or more, more preferably 0.5 μm or more, and even more preferably 0.7 μm or more, from the viewpoint of further improving charge acceptance and ISS cycle characteristics. The average particle diameter of the negative electrode active material is preferably 2.5 μm or less, more preferably 2 μm or less, and even more preferably 1.5 μm or less from the viewpoint of further improving the ISS cycle characteristics. The average particle diameter of the negative electrode active material is an average particle diameter of the negative electrode active material in the negative electrode material after chemical conversion. The average particle diameter 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) image of the negative electrode material in the central part of the negative electrode after chemical conversion in the range of 10 μm in length × 10 μm in width. It can be obtained as a numerical value obtained by arithmetically averaging the length (maximum particle size) value.

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 acceptance, ISS cycle characteristics, etc.) 95 mass% or more is more preferable, and 98 mass% or more is still more preferable. The upper limit of the content of the negative electrode active material may be 100% by mass or less. The said content of a negative electrode active material is 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 an additive, a resin having at least one selected from the group consisting of a sulfone group (sulfonic acid group, sulfo group) and a sulfonic acid group (a group in which a hydrogen atom of the sulfone group is substituted with an alkali metal) (sulfone group and And / or a resin having a sulfonate group); barium sulfate; a carbon material (carbonaceous conductive material, excluding carbon fiber); a reinforcing short fiber. When the negative electrode material contains a resin having at least one selected from the group consisting of a sulfone group and a sulfonate group, the charge acceptability can be further improved.

Examples of the resin having a sulfone group and / or a sulfonate group include bisphenol resins having a sulfone group and / or a sulfonate group (hereinafter simply referred to as “bisphenol resins”), lignin sulfonic acid, and lignin sulfonate. It is done. Lignin sulfonic acid is a compound in which a part of the degradation 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 acceptance.

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

A 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, 1,1-bis (4-hydroxyphenyl) ethane, , 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).

Examples of the aminoalkylsulfonic acid include aminomethanesulfonic acid, 2-aminoethanesulfonic acid, 3-aminopropanesulfonic acid, 2-methylaminoethanesulfonic acid and the like. Examples of aminoalkyl sulfonic acid derivatives include compounds in which the hydrogen atom of aminoalkyl sulfonic acid is substituted with an alkyl group (for example, an alkyl group having 1 to 5 carbon atoms) or the like, and sulfone groups of aminoalkyl sulfonic acid (—SO ₃ H). Examples include alkali metal salts in which a hydrogen atom is substituted with an alkali metal (for example, sodium or potassium). Examples of aminoarylsulfonic acid include aminobenzenesulfonic acid (4-aminobenzenesulfonic acid and the like), aminonaphthalenesulfonic acid and the like. Examples of aminoaryl sulfonic acid derivatives include compounds in which a hydrogen atom of aminoaryl sulfonic acid is substituted with an alkyl group (for example, an alkyl group having 1 to 5 carbon atoms) or the like, a sulfone group of aminoaryl sulfonic acid (—SO ₃ H) Examples include alkali metal salts in which a hydrogen atom is substituted with an alkali metal (for example, sodium or potassium).

Examples of formaldehyde derivatives include paraformaldehyde, hexamethylenetetramine, and trioxane.

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

[In Formula (I), X ¹ represents a divalent group, A ¹ represents an alkylene group having 1 to 4 carbon atoms, or an arylene group, 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 represents an alkali metal or a hydrogen atom, n11 represents an integer of 1 to 600, and n12 represents 1 to 3 N13 represents 0 or 1. ]

[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, 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 represents an alkali metal or a hydrogen atom, n 21 represents an integer of 1 to 600, and n ²² represents 1 to 3 N23 represents 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 vary depending on synthesis conditions and the like. As the bisphenol-based 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.

X ¹ and X ² include, for example, alkylidene groups (methylidene group, ethylidene group, isopropylidene group, sec-butylidene group, etc.), cycloalkylidene groups (cyclohexylidene group, etc.), phenylalkylidene groups (diphenylmethylidene group, An organic group such as a phenylethylidene group; a sulfonyl group; an isopropylidene group (—C (CH ₃ ) ₂ —) is preferable from the viewpoint of further excellent charge acceptability, and a sulfonyl group from the viewpoint of further excellent discharge characteristics. The 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 alkylene groups having 1 to 4 carbon atoms such as a methylene group, an ethylene group, a propylene group, and a butylene group; and divalent arylene groups 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 metal 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 ISS cycle characteristics and solubility in a solvent. n12 and n22 are preferably 1 or 2, and more preferably 1, from the viewpoint of improving the charge acceptance, discharge characteristics, and ISS cycle characteristics in a well-balanced manner. n13 and n23 vary depending on production conditions, but 0 is preferable from the viewpoint of further excellent ISS cycle characteristics and excellent storage stability of a bisphenol-based resin.

The weight average molecular weight of a resin having a sulfonic group and / or a sulfonic acid group (such as a bisphenol-based resin) suppresses the elution of a resin having a sulfonic group and / or a sulfonic acid group from an electrode to an electrolyte in a lead storage battery Is preferably 3000 or more, more preferably 10,000 or more, still more preferably 20000 or more, and particularly preferably 30000 or more. The weight average molecular weight of the resin having a sulfone group and / or a sulfonate group is 200000 from the viewpoint that the ISS cycle characteristics are easily improved by suppressing the decrease in the adsorptivity to the electrode active material and the decrease in the dispersibility. The following is preferable, 150,000 or less is more preferable, and 100,000 or less is still more preferable.

The weight average molecular weight of the resin having a sulfone group and / or a sulfonate group can be measured, for example, by gel permeation chromatography (hereinafter referred to as “GPC”) under the following conditions. (GPC conditions)
Apparatus: High performance liquid chromatograph LC-2200 Plus (manufactured by JASCO Corporation)
Pump: PU-2080
Differential refractometer: RI-2031
Detector: UV-visible spectrophotometer UV-2075 (λ: 254 nm)
Column oven: CO-2065
Column: 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 rate: 0.6 mL / min Molecular weight standard sample: Polyethylene glycol (molecular weight: 1.10 × 10 ⁶ , 5.80 × 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 Tosoh Corporation), diethylene glycol (molecular weight: 1 .06 × 10 ² ; manufactured by Kishida Chemical Co., Ltd.), dibutylhydroxytoluene (molecular weight: 2.20 × 10 ² ; manufactured by Kishida Chemical Co., Ltd.)

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

[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 increasing 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, the method of adjusting the addition amount of sulfuric acid and water when preparing the negative electrode material paste, the method of refining the active material at the stage of the unformed 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 producing the current collector include a casting method, an expanding method, and a punching method. Examples of the current collector material include a lead-calcium-tin alloy and a lead-antimony alloy. A small amount of selenium, silver, bismuth or the like can be added to these. For example, the current collector can be obtained by forming these materials into a lattice shape or a mesh shape by the above-described manufacturing method. The material and / or manufacturing method of the positive and negative electrode current collectors may be the same or different from each other.

<Method for producing lead-acid battery>
The method for manufacturing a lead storage battery according to the present embodiment includes, for example, an electrode manufacturing process for obtaining electrodes (positive electrode and negative electrode) and an assembly process for obtaining a lead storage battery by assembling constituent members including the electrodes.

In the electrode manufacturing process, for example, after filling an electrode material paste (a positive electrode material paste and a negative electrode material paste) into a current collector (a cast lattice obtained by a casting method, an expanded lattice obtained by an expanding method, etc.), aging and An unformed electrode is obtained by drying. The positive electrode material paste contains, for example, a raw material (lead powder or the like) of the positive electrode active material, and may further contain other additives. The negative electrode material paste preferably contains a raw material for the negative electrode active material (such as lead powder), and preferably contains a resin having a sulfone group and / or a sulfonate group (such as a bisphenol-based resin) as a dispersant. Further, 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 (Pb ₃ O ₄ ) may be used as a raw material for the positive electrode active material from the viewpoint of shortening the chemical formation time.

First, an additive (reinforcing short fiber, etc.) is added to the raw material of the positive electrode active material and dry mixed to obtain a mixture. And a positive electrode material paste is obtained by adding and knead | mixing a sulfuric acid (dilute sulfuric acid etc.) and a solvent (water, such as ion-exchange water, an organic solvent) to this mixture.

An unformed positive electrode can be obtained by filling the positive electrode material paste into the current collector and then aging and drying.

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 positive electrode active material (lead powder, etc.) 0.05 to 0.3% by mass is more preferable.

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

The negative electrode material paste can be obtained, for example, by the following method. First, an additive (a resin having a sulfone group and / or a sulfonate group, a carbon material, a reinforcing short fiber, barium sulfate, or the like) is added to the raw material of the negative electrode active material and dry mixed to obtain a mixture. And a negative electrode material paste is obtained by adding and knead | mixing a sulfuric acid (diluted sulfuric acid etc.) and a solvent (water, such as ion-exchange water, an organic solvent) to this mixture. An unformed negative electrode can be obtained by filling the negative electrode material paste into the current collector and then aging and drying.

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

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

In the assembling process, for example, the unformed negative electrode and the unformed positive electrode produced as described above are alternately stacked via separators, and the current collectors of the same polarity electrodes are connected (welded, etc.) with a strap. An electrode group is obtained. This electrode group is arranged in a battery case to produce an unformed battery. Next, after injecting an electrolyte into an unformed battery, a direct current is applied to form a battery case. The lead acid battery can be obtained by adjusting the specific gravity of the electrolyte after the formation 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 after chemical conversion of the electrolytic solution (electrolytic solution containing aluminum ions) 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, further preferably 1.27 or more, and 1.275 or more from the viewpoint of further suppressing the osmotic short circuit or freezing and further improving the discharge characteristics. Is particularly preferred. The specific gravity of the electrolytic solution is preferably 1.33 or less, more preferably 1.32 or less, still more preferably 1.31 or less, and particularly preferably 1.30 or less, from the viewpoint of further improving charge acceptability and ISS 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 Electronics Industry Co., Ltd.

The battery case can accommodate electrodes (electrode plates, etc.) inside. The battery case preferably has a box body whose upper surface is opened and a lid body that covers the upper surface of the box body from the viewpoint of easily accommodating the electrode. Note that an adhesive, heat welding, laser welding, ultrasonic welding, or the like can be appropriately used for bonding the box and the lid. The shape of the battery case is not particularly limited, but a rectangular shape is preferable so that an ineffective space is reduced when an electrode (a plate plate or the like) is accommodated.

The material of the battery case is not particularly limited, but it needs to be resistant to an electrolytic solution (such as dilute sulfuric acid). Specific examples of the material for the battery case include PP (polypropylene), PE (polyethylene), and ABS resin. 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 thermally weld the battery case and the lid.

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

Chemical conversion conditions and specific gravity of sulfuric acid can be adjusted according to the properties of the electrode active material. The chemical conversion treatment is not limited to being performed after the assembly process, and may be performed after aging and drying in the electrode manufacturing process (tank chemical conversion).

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to the following examples.

<Production of lead acid battery>
(Example 1)
[Production of positive electrode plate]
Lead powder and red lead (Pb ₃ O ₄ ) were used as raw materials for the positive electrode active material (lead powder: red lead = 96: 4 (mass ratio)). The raw material for the positive electrode active material, 0.07 parts by mass of reinforcing short fibers (acrylic fibers) with respect to 100 parts by mass of the positive electrode active material, and water were mixed and kneaded. Then, it knead | mixing, adding dilute sulfuric acid (specific gravity 1.280) little by little, and produced the positive electrode material paste. An expanded lattice (positive electrode current collector) produced by subjecting a rolled sheet made of a lead alloy to an expanding process was filled with this positive electrode material paste. Next, the grid (positive electrode current collector) filled with the positive electrode material paste was aged for 24 hours in an atmosphere at a temperature of 50 ° C. and a humidity of 98%. Then, it dried and produced the unchemically formed positive electrode plate.

[Production of negative electrode plate]
Lead powder was used as a raw material for the negative electrode active material. For 100 parts by mass of the lead powder, Bispers P215 (condensation product of bisphenol compound, aminobenzenesulfonic acid and formaldehyde, trade name, manufactured by Nippon Paper Industries Co., Ltd.) 0.2 parts by mass (solid content conversion), for reinforcement A mixture containing 0.1 parts by mass of short fibers (acrylic fibers), 1.0 part by mass of barium sulfate and 0.2 parts by mass of carbon material (furnace black) was added and dry-mixed, and then water was added and kneaded. Subsequently, the mixture was kneaded while dilute sulfuric acid (specific gravity 1.280) was added little by little to prepare a negative electrode material paste. This negative electrode material paste was filled in an expanded lattice (negative electrode current collector) produced by subjecting a rolled sheet made of a lead alloy to an expanding process. Next, the grid body (negative electrode current collector) filled with the negative electrode material paste was aged for 24 hours in an atmosphere of a temperature of 50 ° C. and a humidity of 98%. Then, it dried and produced the unchemically formed negative electrode plate.

[Preparation of separator]
A long sheet-like material containing polyethylene and silica particles and having a plurality of linear ribs and mini-ribs arranged on one side is formed into a bag shape so that the surface on which the ribs and mini-ribs are arranged is located outside. It processed and the bag-shaped separator was prepared (refer FIG.1 and FIG.3). Each of the ribs and the mini-ribs is disposed substantially parallel to each other and extends in the longitudinal direction of the separator. In the short direction of the separator, the first region including the rib is located between the two second regions including the mini-rib. Details of the separator are shown below.
Total thickness: 0.75 mm (base portion 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
-Number of miniribs in each of the second regions: 20-Silica particles: The number of silica particles having a particle size (longest diameter) of 2 μm or more is determined by analyzing the cross section of the separator with a scanning electron microscope (SEM). Nine within a range of 30 μm × 40 μm arbitrarily selected.

[Battery assembly]
An unformed negative electrode plate was accommodated in the bag-shaped separator. Next, five unchemically formed positive electrode plates and six unchemically formed negative electrode plates accommodated in the bag-shaped separator were alternately laminated so that the ribs of the separator were in contact with the positive electrode plate. Subsequently, the ears of the same polarity electrode plates were welded together by a cast on strap (COS) method to produce an electrode plate group. The electrode plate group was inserted into a battery case to assemble a 2V single cell battery (corresponding to a B19 size single cell defined in JIS D 5301). Dilute sulfuric acid (electrolytic solution) having a specific gravity of 1.23 in which aluminum sulfate anhydride was dissolved so that the aluminum ion concentration was 0.08 mol / L was injected into the battery. Then, in a 50 degreeC water tank, it formed for 16 hours with the energizing current 10A, the specific gravity of the electrolyte solution after formation was adjusted to 1.280, and the lead acid battery of Example 1 was obtained.

[Mass ratio of positive electrode material to negative electrode material]
The formed lead-acid battery was disassembled, the positive electrode plate and the negative electrode plate accommodated in the separator were taken out of the battery, and the negative electrode plate was taken out of the separator. The positive electrode plate and the negative electrode plate were washed with water for 1 hour and then left to dry at 50 ° C. for about 1 day. Thereafter, the dried positive electrode plate and negative electrode plate after the formation of the positive electrode material and the formed negative electrode material were removed from the positive electrode current collector and the negative electrode current collector, respectively. The amount of change in the mass of the positive electrode plate and the negative electrode plate before and after removing the electrode material (the positive electrode material after conversion and the negative electrode material after conversion) was determined as the mass of the positive electrode material and the negative electrode material, respectively. From the result, the mass ratio of the positive electrode material to the negative electrode material (positive electrode material / negative electrode material) was calculated. The results are shown in Table 1.

[Total amount of oxygen and silicon in the separator]
First, the separator before battery assembly was cut by an ion milling apparatus E-3500 (trade name, manufactured by Hitachi High-Technologies Corporation) to expose the cross section. Next, EDX analysis of the separator cross section 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, and the abundances of carbon, oxygen, and silicon were quantified and converted to the mass of each element. Based on the total mass of carbon, oxygen and silicon obtained, the total mass (% by mass) of oxygen and silicon in the separator was calculated. The conditions for mapping analysis are as follows: acceleration voltage is 15 kV, spot size is 72, pressure is 35 Pa in low vacuum mode, dwell time is 1 millisecond, process time is T4, number of pixels is 512 × 384, and integration is 5 times. It was. Table 1 shows the quantitative results of each element.

[Specific surface area measurement]
A sample for measuring the specific surface area was prepared by the following procedure. First, the formed battery was disassembled, electrode plates (positive and negative plates) were taken out, washed with water, and dried at 50 ° C. for 24 hours. Next, 2 g of an electrode material (a positive electrode material and a negative electrode material) was collected from the center 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 nitrogen gas adsorption amount at a liquid nitrogen temperature by a multipoint method while cooling the measurement sample prepared above with liquid nitrogen. The measurement conditions were as follows. As a result of the measurement, 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}
Apparatus: HM-2201FS (manufactured by Macsorb)
Degassing time: 10 minutes at 130 ° C. Cooling: 4 minutes with liquid nitrogen Adsorbed gas flow rate: 25 mL / min

(Examples 2 and 3)
Examples 2 and 3 are the same as Example 1 except that dilute sulfuric acid having a specific gravity of 1.280 (after chemical conversion) prepared so that the aluminum ion concentration becomes the value shown in Table 1 is used as the electrolytic solution. A lead storage battery was prepared.

(Examples 4 to 6)
The same as Example 1 except that the amounts of the positive electrode material and the negative electrode material were adjusted so that the mass ratio (positive electrode material / negative electrode material) of the positive electrode material after conversion to the negative electrode material after conversion was the value shown in Table 1. Thus, lead acid batteries of Examples 4 to 6 were produced.

(Example 7)
Except for using dilute sulfuric acid having a specific gravity of 1.280 (after chemical conversion) in which aluminum sulfate anhydride and sodium sulfate are dissolved so that the aluminum ion concentration and sodium ion concentration are the values shown in Table 1, as the electrolytic solution, In the same manner as in Example 1, a lead storage battery of Example 7 was produced.

(Comparative Example 1)
A lead acid battery of Comparative Example 1 was produced in the same manner as Example 1 except that dilute sulfuric acid having a specific gravity of 1.280 (after chemical conversion) not containing aluminum ions was used as the electrolytic solution.

(Comparative Example 2)
Except having adjusted the quantity of the positive electrode material and the negative electrode material so that the mass ratio (positive electrode material / negative electrode material) of the positive electrode material after conversion with respect to the negative electrode material after conversion was 0.95, it carried out similarly to Example 1. The lead acid battery of Comparative Example 2 was produced.

<Evaluation of battery characteristics>
About the lead acid battery obtained by the Example and the comparative example, the 5-hour rate capacity cycle characteristic, the low-temperature high-rate discharge performance, the charge acceptance property, the suppression effect of an osmotic short circuit, and the ISS cycle characteristic were evaluated as follows. The results are shown in Table 1. “-” In Table 1 means that aluminum sulfate or sodium sulfate was not blended.

(5 hour rate capacity cycle characteristics)
The produced lead storage battery was discharged at a constant current of 5.6 A at an ambient temperature of 25 ° C., and the 5-hour rate discharge capacity was calculated from the discharge duration until the cell voltage fell below 1.75 V. Thereafter, constant current charging was performed at 5.6 A until the 5-hour charge capacity was 150% of the 5-hour discharge capacity. Next, constant current discharge was performed at 5.6 A until the cell voltage reached 1.75V. The charging and discharging were repeated. With respect to the initial 5-hour rate discharge capacity, when the obtained 5-hour rate discharge capacity was less than 50%, the cycle was measured. The 5-hour rate capacity cycle characteristics were evaluated relative to the measurement result of Comparative Example 1 as 100.

(Low temperature high rate discharge performance)
The produced lead storage battery was discharged at a constant current of 150 A at an ambient temperature of −15 ° C., and the discharge duration until the cell voltage fell below 1.0 V was measured. The low-temperature high-rate discharge performance was evaluated relative to the measurement result of Comparative Example 1 as 100.

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

(Infiltration short-circuit suppression effect)
The produced lead acid battery was discharged at a constant current of 1.4 A at an ambient temperature of 25 ° C. Next, after the cell voltage was discharged to 1.75 V, the lead storage battery was connected to a 10 W lamp at an ambient temperature of 40 ° C. and left in an overdischarged state for 5 days. Thereafter, the battery was charged for 8 hours at a cell voltage of 2.33 V under a limiting current of 25 A at an ambient temperature of 25 ° C. Repeat the above discharging and charging, and short-circuit the time point when current fluctuation (current fluctuation of 0.3 A or more) or high end current (current about 8 hours after charging starts) (3 A or more) occurs during charging. And the number of repetitions until short circuit was measured. The suppression effect of the penetration short circuit was evaluated relative to the measurement result of Comparative Example 1 as 100.

(ISS cycle characteristics)
The produced lead-acid battery is subjected to constant current discharge for 45 A-59 seconds and 300 A-1 seconds at an ambient temperature of 25 ° C., followed by constant current / constant voltage charging for 100 A-2.33 V-60 seconds. A test for one cycle was performed. This test is a cycle test that simulates the use of lead-acid batteries in ISS cars. In this cycle test, since the amount of charge is small with respect to the amount of discharge, if the charging is not performed completely, the charging gradually becomes insufficient. As a result, the first-second voltage when the discharge current is 300 A for 1 second is gradually reduced. That is, if the negative electrode is polarized during constant current / constant voltage charging and switched to constant voltage charging at an early stage, the charging current is attenuated, resulting in insufficient charging. In this cycle test, the first-second voltage at the time of 300 A discharge was measured, and the cycle number when the first-second voltage fell below 1.2 V was defined as the ISS cycle characteristics. The ISS cycle characteristics were evaluated relative to the measurement result of Comparative Example 1 as 100.

As is clear from the results shown in Table 1, it was confirmed that the lead storage batteries of Examples 1 to 7 were superior to the lead storage batteries of Comparative Examples 1 and 2 in the evaluation results of the penetration short circuit. Since the lead acid batteries of Examples 1 to 7 have a mass ratio of the positive electrode material after chemical conversion to the negative electrode material after chemical conversion is 1.05 or more, the mass ratio does not satisfy the above conditions, compared with the lead acid battery of Comparative Example 2 The decrease in the specific gravity of the electrolyte in the overdischarged state is small, and the increase in the solubility of lead sulfate can be suppressed, so that it is presumed that the effect of suppressing the penetration short circuit is excellent. On the other hand, the lead acid battery of Comparative Example 1 in which the mass ratio of the positive electrode material after chemical conversion to the negative electrode material after chemical conversion is 1.05 or more but the electrolyte does not contain aluminum ions is different from the lead acid batteries of Examples 1-7. In comparison, it was confirmed that the evaluation result of the penetration short circuit was inferior.

DESCRIPTION OF

SYMBOLS

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

Claims

A positive electrode and a negative electrode facing each other through a separator, and an electrolyte solution,
The separator comprises polyolefin and silica;
The positive electrode has a positive electrode current collector and a positive electrode material held by the positive electrode current collector;
The negative electrode has a negative electrode current collector and a negative electrode material held by the negative electrode current collector,
The electrolyte contains aluminum ions;
The lead acid battery whose mass ratio of the said positive electrode material after conversion with respect to the said negative electrode material after conversion is 1.05 or more.
The elemental analysis by energy dispersive X-ray spectroscopy, wherein the total mass of oxygen and silicon in the separator is 30 to 80 mass% based on the total mass of carbon, oxygen and silicon. Lead acid battery.
The lead storage battery according to claim 1 or 2, wherein the concentration of the aluminum ions in the electrolytic solution is 0.01 to 0.3 mol / L.
The lead acid battery according to any one of claims 1 to 3, wherein the electrolytic solution further contains sodium ions.
The lead acid battery according to any one of claims 1 to 4, wherein a mass ratio of the positive electrode material after chemical conversion to the negative electrode material after chemical conversion is 1.05 to 1.60.
The lead acid battery according to any one of claims 1 to 5, wherein a mass ratio of the positive electrode material after chemical conversion to the negative electrode material after chemical conversion is 1.05 to 1.50.
The lead acid battery according to any one of claims 1 to 6, wherein a specific surface area of the positive electrode material is 3 m 2 / g or more.
The lead acid battery according to any one of claims 1 to 7, wherein a specific surface area of the negative electrode material is 0.4 m 2 / g or more.
The separator is a long separator having a first rib, a second rib, and a base;
The base portion supports the first rib and the second rib;
The first rib and the second rib extend in a longitudinal direction of the separator;
Each of both end portions in the short direction of the separator includes 10 to 40 second ribs,
The lead acid battery according to any one of claims 1 to 8, wherein a region between the both end portions includes the first rib.