JP2022085747A - Lead acid battery - Google Patents

Abstract

To provide a lead acid battery having a small amount of overcharge electricity.SOLUTION: A lead acid battery 1 includes a positive electrode plate 3 and a negative electrode plate 2. The negative electrode plate 2 includes a negative electrode current collector 2a and a negative electrode material supported by the negative electrode current collector. The negative electrode material includes a first negative electrode material, and a second negative electrode material arranged outside the first negative electrode material. The content (ppm) of the polymer compound in the first negative electrode material is higher than the content (ppm) of the polymer compound in the second negative electrode material. The polymer compound has a peak in the range of 3.2 ppm or more and 3.8 ppm or less in the chemical shift of the 1H-NMR spectrum measured using deuterated chloroform as a solvent.SELECTED DRAWING: Figure 1

Description

The present invention relates to a lead storage battery.

Lead-acid batteries are used in various applications such as in-vehicle use and industrial use. Lead-acid batteries usually include a negative electrode plate, a positive electrode plate, a separator (or mat), an electrolytic solution, and the like. Usually, each electrode plate contains a current collector and an electrode material supported by the current collector.

The electrode material of the electrode plate usually has an overall uniform composition. On the other hand, Patent Document 1 (Japanese Unexamined Patent Publication No. 59-042771) states that "a paste for an anode containing fine particles of a thermoplastic resin after forming a layer in which fine particles of a thermoplastic resin are dispersed on the surface of a lattice body". A method for manufacturing an anode plate for a lead storage battery, which comprises filling the particles. ”.

Patent Document 2 (Japanese Unexamined Patent Publication No. 2000-149981) describes a polymer containing any one of the group consisting of polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, polyacrylic acid, or esters thereof having a degree of polymerization of 30 or more and 3000 or less. Disclosed is a lead storage battery comprising either a compound or a polymer compound and colloidal barium sulfate particles in an electrolytic solution and / or an electrode active material molded body.

Patent Document 3 (Japanese Unexamined Patent Publication No. 9-147874) is a negative electrode plate for a lead storage battery in which a paste-type active material containing a shrink-proofing agent is filled in a current collector, and the poly represented by a specific chemical formula as the shrinkage-proofing agent. Disclosed is a negative electrode plate for a lead storage battery, which uses oxyperfluoroethylene phenylamine and contains 0.005 to 3% by weight of the polyoxyperfluoroethylene phenylamine with respect to the paste-type active material. ing.

JP-A-59-042771A Japanese Unexamined Patent Publication No. 2000-149981 Japanese Unexamined Patent Publication No. 9-147874

In lead-acid batteries, overcharging causes deterioration of the positive electrode current collector and reduction of the electrolytic solution. Therefore, when the amount of overcharged electricity is large, the deterioration of the battery is likely to be accelerated.

One aspect of the present invention relates to a lead storage battery. The lead storage battery includes a positive electrode plate and a negative electrode plate, the negative electrode plate includes a negative electrode collector and a negative electrode material supported by the negative electrode collector, and the negative electrode material is the negative electrode collector. The first negative electrode material in contact with the electric body and the second negative electrode material arranged outside the first negative electrode material are included, and are based on the mass of the polymer compound in the first negative electrode material. The content (ppm) is higher than the mass-based content (ppm) of the polymer compound in the second negative electrode material, and the polymer compound is measured using heavy chloroform as a solvent ¹ H-NMR. It has a peak in the range of 3.2 ppm or more and 3.8 ppm or less in the chemical shift of the spectrum.

Another aspect of the invention relates to other lead acid batteries. The other lead storage battery includes a positive electrode plate and a negative electrode plate, the negative electrode plate includes a negative electrode current collector, and a negative electrode electrode material supported by the negative electrode current collector, and the negative electrode material is the negative electrode material. The mass of the polymer compound in the first negative electrode material, including the first negative electrode material in contact with the negative electrode current collector and the second negative electrode material arranged outside the first negative electrode material. The reference content (ppm) is higher than the mass-based content (ppm) of the polymer compound in the second negative electrode material, and the polymer compound contains a repeating structure of an _{oxyC 2-4} alkylene unit. ..

According to the present invention, a lead storage battery having a small amount of overcharge electricity can be obtained.

It is an exploded perspective view which cut out a part which shows the appearance and the internal structure of the lead storage battery which concerns on one aspect of this invention. It is sectional drawing of an example of the negative electrode plate of the lead storage battery which concerns on one aspect of this invention. It is sectional drawing in the line IIB-IIB of the negative electrode plate shown in FIG. 2A. It is sectional drawing of another example of the negative electrode plate of the lead storage battery which concerns on one aspect of this invention. It is a graph which shows a part of the result of an Example. It is a graph which shows the other part of the result of an Example.

Hereinafter, embodiments of the present invention will be described with reference to examples, but the present invention is not limited to the examples described below. In the following description, specific numerical values and materials may be exemplified, but other numerical values and materials may be applied as long as the effects of the present invention can be obtained. In this specification, when the term "numerical value A to numerical value B" is used, the range includes the numerical value A and the numerical value B.

(Lead-acid battery)
The lead storage battery according to the present embodiment includes a positive electrode plate and a negative electrode plate. The negative electrode plate includes a negative electrode current collector and a negative electrode material supported by the negative electrode current collector. The negative electrode material includes a first negative electrode material and a second negative electrode material arranged outside the first negative electrode material. The mass-based content (ppm) of the polymer compound in the first negative electrode material is higher than the mass-based content (ppm) of the polymer compound in the second negative electrode material. Hereinafter, the polymer compound may be referred to as "polymer compound (P)". In the following, the content of the polymer compound (P) means a mass-based content (ppm, content rate) unless otherwise specified.

The first example of the polymer compound (P) is a polymer compound having a peak in the range of 3.2 ppm or more and 3.8 ppm or less in a chemical shift of ¹ H-NMR spectrum measured using deuterated chloroform as a solvent. .. In this specification, ^{1 1} H-NMR spectrum is a spectrum measured using deuterated chloroform as a solvent unless otherwise specified. A second example of the polymer compound (P) is a polymer compound comprising a repeating structure of _{oxyC 2-4} alkylene units. The polymer compound contained in the first example of the polymer compound (P) and the polymer compound contained in the second example of the polymer compound (P) overlap at least in part. As the polymer compound (P), a commercially available one may be used. Alternatively, the polymer compound (P) may be synthesized by a known method.

The second negative electrode electrode material is arranged outside the first negative electrode material (outside in the thickness direction of the negative electrode plate). The second negative electrode material may be arranged only on the outside of one of the first negative electrode materials. Alternatively, the second negative electrode material may be arranged outside both of the first negative electrode materials. In this case, the second negative electrode material is arranged so as to sandwich the first negative electrode material. From one viewpoint, the mass-based content (ppm) of the polymer compound (P) in the negative electrode electrode material is larger in the central portion in the thickness direction of the negative electrode plate than in the surface side of the negative electrode plate. Hereinafter, the central portion in the thickness direction of the negative electrode plate may be simply referred to as “the central portion of the negative electrode plate”. The first negative electrode material may be in contact with the negative electrode current collector.

In a lead-acid battery, water in the electrolytic solution is electrolyzed by the negative electrode plate during charging to generate hydrogen gas. When the amount of overcharged electricity is large, the amount of decrease in the electrolytic solution becomes large due to the electrolysis of water. Further, when the amount of overcharged electricity is large, the deterioration of the positive electrode current collector is promoted. Therefore, in lead-acid batteries, it is particularly important to reduce the amount of overcharged electricity.

As a result of the study, the inventors of the present application can particularly suppress the amount of hydrogen gas generated by increasing the content of the polymer compound (P) in the central portion of the negative electrode plate, and as a result, reduce the amount of overcharged electricity. I found that I could do it. The present invention is based on this new finding. Furthermore, the inventors of the present application have newly found that the performance of high-rate discharge at low temperature is improved by increasing the content of the polymer compound (P) in the central portion of the negative electrode plate. These effects will be described in Examples.

During overcharging, where a large amount of hydrogen gas is generated, the amount of hydrogen gas generated is larger in the central portion in the thickness direction of the negative electrode plate than in the surface portion of the negative electrode plate. Therefore, by arranging the polymer compound (P) having an effect of suppressing the amount of overcharged electricity in the central portion of the negative electrode plate, it is possible to particularly reduce the amount of overcharged electricity.

As will be described later, the polymer compound (P) covers the surface of lead in the negative electrode material. In high-rate discharge at low temperature, diffusion of sulfuric acid becomes a rate-determining factor, and the reaction in the vicinity of the surface of the negative electrode plate is mainly more than the reaction in the central portion of the negative electrode plate. Therefore, if the content of the polymer compound (P) on the surface of the negative electrode plate is high, the duration of the low temperature and high rate discharge is sharply reduced. By unevenly distributing the polymer compound (P) in the central portion of the negative electrode plate, the content of the polymer compound (P) on the surface portion of the negative electrode plate is reduced while maintaining the content of the polymer compound (P) in the entire negative electrode plate. can. This makes it possible to suppress a decrease in the performance of the lead-acid battery (decrease in the duration of low-temperature high-rate discharge) when the polymer compound (P) is added to the negative electrode material.

The reason why the amount of overcharged electricity can be reduced by the polymer compound (P) is considered to be as follows. Since the polymer compound (P) contains a repeating structure of an _{oxyC 2-4} alkylene unit and the like, it is easy to form a linear structure. Therefore, the polymer compound (P) added to the negative electrode material covers the surface of lead in the negative electrode material thinly and widely. By covering the surface of lead with the polymer compound (P), the hydrogen overvoltage rises, and as a result, side reactions that generate hydrogen during overcharging are less likely to occur. On the other hand, if the amount of the polymer compound (P) added is large, the charge acceptability may decrease. In the present invention, the content of the polymer compound (P) in the central portion of the negative electrode plate, which generates a large amount of hydrogen gas during overcharging, is large. Therefore, it is possible to effectively reduce the amount of overcharged electricity while suppressing the amount of the polymer compound (P) in the entire negative electrode plate. That is, according to the present invention, high charge acceptance performance and low overcharge electricity amount can be realized.

The polymer compound (P) preferably contains a repeating structure of _{oxyC 2-4} alkylene units. When a polymer compound (P) containing a repeating structure of an _{oxyC 2-4} alkylene unit is used, the polymer compound (P) is more easily adsorbed to lead and has a linear structure, so that the lead surface is made thinner. It is thought that it will be easier to cover. Therefore, the amount of overcharged electricity can be reduced more effectively, and the effect of suppressing the decrease in charge acceptability can be further enhanced.

The polymer compound (P) may contain at least one selected from the group consisting of a hydroxy compound containing a repeating structure of an _{oxyC 2-4} alkylene unit, an etherified product of the hydroxy compound, and an esterified product of the hydroxy compound. An example of a hydroxy compound containing a repeating structure of an Oxy C _2-4 alkylene unit will be described later.

The polymer compound (P) may be an esterified product of a polyalkylene glycol having an alkylene group having 2 to 4 carbon atoms. According to this configuration, a lead storage battery having a particularly low charge electricity amount and a particularly high low temperature and high rate discharge performance can be obtained. The polymer compound (P) may be at least one selected from the group consisting of, for example, an esterified product of polyethylene glycol and an esterified product of polypropylene glycol.

The negative electrode current collector may include a plurality of linear portions (thin rod-shaped portions from another viewpoint). In that case, the first negative electrode material may be arranged in the gap between the plurality of linear portions. The first negative electrode material may be arranged not only on the void but also on the outside of the linear portion and the outside of the void. In a typical example, the negative electrode material is composed of a first negative electrode material and a second negative electrode material.

An example of the negative electrode material is composed of a first electrode material and a second electrode material, and the second electrode material is arranged so as to sandwich the first negative electrode material and a plurality of linear portions. There is. In this case, the second negative electrode electrode material is arranged in layers on the two main surfaces of the negative electrode plate. In this case, the first negative electrode material may also be arranged in layers.

The negative electrode current collector may have a grid portion composed of a plurality of linear portions. In that case, the first negative electrode material is arranged in the voids between the lattices. The first negative electrode material may be arranged not only on the void but also on the outside of the lattice portion and the outside of the void. Examples of the negative electrode current collector having a lattice portion include a current collector including an expanded lattice formed by an expand process.

The first negative electrode material may form a first layered portion. The second negative electrode material may form a second layered portion arranged outside the first layered portion. Alternatively, the boundary between the first negative electrode material and the second negative electrode material may not be clear. For example, the content of the polymer compound (P) may gradually decrease from the central portion in the thickness direction of the negative electrode plate toward the surface side of the negative electrode plate.

In one example, when the negative electrode material arranged on the negative electrode plate is divided into three regions in the thickness direction, the content of the polymer compound (P) in the central first region is the content of the polymer compound (P) in the two second regions on both sides thereof. It may be higher than the content of the polymer compound (P) in the region of. The negative electrode material arranged in the first region is in contact with the negative electrode current collector. When the thickness of the negative electrode material arranged on the negative electrode plate is T, the thickness T1 of the first region is in the range of 0.2T to 0.8T (for example, in the range of 0.4T to 0.7T). The thickness T2 of one second region may be in the range of 0.1T to 0.4T (eg, in the range of 0.15T to 0.3T). The two boundaries separating the three regions may coincide with the surfaces on both sides of the negative electrode current collector.

The thickness of the negative electrode plate is not particularly limited, and may be in the range of 0.6 mm to 2.0 mm (for example, in the range of 1.0 mm to 1.4 mm) or in a range other than this.

The content Ct (2) of the polymer compound in the second negative electrode material may be in the range of 0 to 0.7 times the content Ct (1) of the polymer compound in the first negative electrode material. According to this range, high charge acceptance performance and low overcharge electricity amount can be realized in a particularly well-balanced manner. The content Ct (2) may be 0 times or more, 0.1 times or more, or 0.3 times or more the content Ct (1). The content Ct (2) may be 0.7 times or less, 0.5 times or less, 0.4 times or less, or 0.3 times or less the content Ct (1). These lower and upper limits can be combined arbitrarily as long as there is no contradiction. The content Ct (2) is in the range of 0 to 0.5 times, the range of 0 to 0.4 times, the range of 0.1 to 0.7 times, and 0.3 to 0 times the content Ct (1). It may be in the range of 7 times, or 0.1 to 0.5 times.

The content of the polymer compound (P) in the first negative electrode material may be in the range of 80 ppm to 500 ppm (for example, in the range of 80 ppm to 400 ppm) on a mass basis. According to this range, high charge acceptance performance and low overcharge electricity amount can be realized in a particularly well-balanced manner.

The content of the polymer compound (P) in the negative electrode material may satisfy at least one of the following conditions (1) to (3). For example, the following conditions (1) and (2), (1) and (3), (2) and (3) may be satisfied. Alternatively, all of the following conditions (1) to (3) may be satisfied.
(1) The content of the polymer compound (P) in the first negative electrode material is 40 ppm or more, 60 ppm or more, 80 ppm or more, 140 ppm or more, or 280 ppm or more on a mass basis. The content is 1000 ppm or less, 500 ppm or less, 400 ppm or less, or 300 ppm or less on a mass basis. These lower and upper limits can be combined arbitrarily as long as there is no contradiction. For example, the content is in the range of 40 to 1000 ppm, 60 to 500 ppm, 60 to 400 ppm, 80 to 500 ppm, 80 ppm to 400 ppm, or 60 to 300 ppm on a mass basis. May be good.
(2) The relationship between the polymer compound content Ct (2) in the second negative electrode material and the polymer compound content Ct (1) in the first negative electrode material is the above-exemplified relationship.
(3) The content of the polymer compound (P) in the entire negative electrode material is 40 ppm or more, 60 ppm or more, 80 ppm or more, 140 ppm or more, or 280 ppm or more on a mass basis. The content is 400 ppm or less, or 300 ppm or less on a mass basis.

The lead-acid battery may be either a control valve type (sealed type) lead-acid battery (VRLA type lead-acid battery) or a liquid type (vent type) lead-acid battery.

In the present specification, the content of the polymer compound (P) in the negative electrode electrode material is determined for the negative electrode plate taken out from the lead storage battery in a fully charged state.

(Explanation of terms)
(Electrode material)
Each electrode material of the negative electrode material and the positive electrode material is usually held in the current collector. The electrode material is a plate from which the current collector is removed. Members such as mats and pacing papers may be attached to the electrode plate. Since such a member (also referred to as a sticking member) is used integrally with the plate, it is included in the plate. When the electrode plate includes a sticking member (mat, pacing paper, etc.), the electrode material excludes the current collector and the sticking member.

(Polymer compound (P))
The polymer compound (P) satisfies at least one of the following conditions (i) and (ii).
Condition (i)
The polymer compound (P) has a peak in the range of 3.2 ppm or more and 3.8 ppm or less in the chemical shift of ¹ H-NMR spectrum measured using deuterated chloroform as a solvent.
Condition (ii)
The polymer compound (P) contains a repeating structure of _{oxyC 2-4} alkylene units.

In condition (i), the peak in the range of 3.2 ppm or more and 3.8 ppm or less is derived from the oxyC _2-4 alkylene unit. That is, the polymer compound (P) that satisfies the condition (ii) is also the polymer compound (P) that satisfies the condition (i). The polymer compound (P) satisfying the condition (i) may contain a repeating structure of a monomer unit other than the _{oxyC 2-4} alkylene unit, and may have a certain molecular weight. The number average molecular weight (Mn) of the polymer compound (P) satisfying the above (i) or (ii) may be, for example, 300 or more.

(Oxy-C _2-4 alkylene unit)
The Oxy-C _2-4 alkylene unit is a unit represented by -OR ^1- . Here, R ¹ represents a C _2-4 alkylene group (an alkylene group having a carbon number in the range of 2 to 4). R ¹ may contain an alkylene group having a different number of carbon atoms.

(Organic shrinkage agent)
The organic shrink-proofing agent refers to an organic compound among compounds having a function of suppressing the shrinkage of lead, which is a negative electrode active material, when the lead storage battery is repeatedly charged and discharged.

(Number average molecular weight)
The number average molecular weight (Mn) is determined by gel permeation chromatography (GPC). The standard substance used to determine Mn is polyethylene glycol.

(Weight average molecular weight)
The weight average molecular weight (Mw) is determined by GPC. The standard substance used when determining Mw is sodium polystyrene sulfonate.

(Sulfur element content in organic shrink proofing agent)
The content of the sulfur element in the organic shrinkage proofing agent is Xμmol / g means that the content of the sulfur element contained in 1 g of the organic shrinkage proofing agent is Xμmol / g.

(Fully charged)
The fully charged state of a liquid lead-acid battery is defined by the definition of JIS D 5301: 2019. More specifically, in a water tank at 25 ° C ± 2 ° C, charging is performed every 15 minutes with a current (A) 0.2 times the value described as the rated capacity (value whose unit is Ah). The state in which the lead-acid battery is charged is regarded as a fully charged state until the terminal voltage (V) of No. 1 or the electrolyte density converted into temperature at 20 ° C. shows a constant value with three valid digits three times in a row. In the case of a control valve type lead-acid battery, the fully charged state is 0.2 times the current (value with Ah as the unit) described in the rated capacity in the air tank at 25 ° C ± 2 ° C (the unit is Ah). In A), constant current constant voltage charging of 2.23 V / cell is performed, and the charging current at the time of constant voltage charging is 0.005 times the value (value with the unit being Ah) described in the rated capacity (A). When it becomes, charging is completed.

A fully charged lead-acid battery is a fully charged lead-acid battery. The lead-acid battery may be fully charged after the chemical conversion, immediately after the chemical conversion, or after a lapse of time from the chemical conversion (for example, after the chemical conversion, the lead-acid battery in use (preferably at the initial stage of use) is fully charged. May be). An initial use battery is a battery that has not been used for a long time and has hardly deteriorated.

(Vertical direction of lead-acid battery or lead-acid battery component)
In the present specification, the vertical direction of the lead-acid battery or the component of the lead-acid battery (plate, battery case, separator, etc.) means the vertical direction of the lead-acid battery in the state where the lead-acid battery is used. Each electrode plate of the positive electrode plate and the negative electrode plate is provided with an ear portion for connecting to an external terminal. In some lead-acid batteries, such as horizontal control valve type lead-acid batteries, the ears are provided so as to project laterally to the sides of the plate, but in many lead-acid batteries, the ears are usually made of the plate. It is provided so as to project upward at the top.

Hereinafter, the lead-acid battery according to the embodiment of the present invention will be described for each of the main constituent requirements, but the present invention is not limited to the following embodiments.

[Lead-acid battery]
(Negative electrode plate)
The negative electrode plate includes a negative electrode current collector and a negative electrode material supported by the negative electrode current collector.

(Negative electrode current collector)
The negative electrode current collector may be formed by casting lead (Pb) or a lead alloy, or may be formed by processing a lead sheet or a lead alloy sheet. Examples of the processing method include expanding processing and punching processing. It is preferable to use a grid-shaped current collector as the negative electrode current collector because it is easy to support the negative electrode material.

The lead alloy used for the negative electrode current collector may be any of Pb—Sb based alloy, Pb—Ca based alloy, and Pb—Ca—Sn based alloy. These leads or lead alloys may further contain, as an additive element, at least one selected from the group consisting of Ba, Ag, Al, Bi, As, Se, Cu and the like. The negative electrode current collector may include a surface layer. The surface layer and the inner layer of the negative electrode current collector may have different compositions. The surface layer may be formed on a part of the negative electrode current collector. The surface layer may be formed on the selvage portion of the negative electrode current collector. The surface layer of the selvage portion may contain Sn or a Sn alloy.

(Negative electrode material)
The negative electrode material contains a polymer compound (P). The negative electrode material further contains a negative electrode active material (specifically, lead or lead sulfate) that develops a capacity by a redox reaction. The negative electrode material may contain at least one selected from the group consisting of carbonaceous materials and other additives. Examples of the additive include, but are not limited to, an organic shrinkage proofing agent, barium sulfate, fibers (resin fiber, etc.) and the like. The negative electrode active material in the charged state is spongy lead, but the unchemical negative electrode plate is usually produced by using lead powder.

(Polymer compound (P))
The first example of the polymer compound (P) has a peak in the range of 3.2 ppm or more and 3.8 ppm or less in the chemical shift of ¹ H-NMR spectrum. Such polymer compound (P) has an oxyC _2-4 alkylene unit. Examples of the _{oxyC 2-4} alkylene unit contained in the polymer compound (P) include an oxyethylene unit, an oxypropylene unit, an oxytrimethylene unit, an oxy2-methyl-1,3-propylene unit, and an oxy1,4-butylene unit. , Oxy 1,3-butylene unit and the like. The polymer compound (P) may have one kind of such oxyC _2-4 alkylene unit, or may have two or more kinds of such oxyC 2-4 alkylene unit.

The polymer compound (P) preferably contains a repeating structure of _{oxyC 2-4} alkylene units. The repeating structure may contain one type of oxyC _{2-4 alkylene unit, or may contain two or more types of oxy C 2-4 alkylene} unit. The polymer compound (P) may contain one kind of the above-mentioned repeating structure, or may contain two or more kinds of the above-mentioned repeating structures.

The polymer compound (P) having a repeating structure of the _{oxyC 2-4} alkylene unit also includes those classified as surfactants (more specifically, nonionic surfactants).

Examples of the polymer compound (P) include hydroxy compounds having a repeating structure of an _{oxyC 2-4} alkylene unit (poly C _2-4 alkylene glycol, a copolymer containing a repeating structure of an oxy C _2-4 alkylene, and a polyol. Poly C _2-4 alkylene oxide adducts, etc.), etherified or esterified compounds of these hydroxy compounds, and the like. Examples of _{polyC 2-4} alkylene glycols include polyethylene glycol, polypropylene glycol, and polyoxyethylene polyoxypropylene glycol.

Examples of the copolymer include a copolymer containing different oxyC _2-4 alkylene units. The copolymer may be a block copolymer.

In the polymer compound (P) containing the repeating structure of the oxyC _{2-4 alkylene unit, the ratio of the oxy C 2-4 alkylene} unit to all the constituent units may be in the range of 50 mol% to 100 mol%, and may be 60 mol%. It may be in the range of ~ 100 mol% (for example, the range of 75 mol% to 100 mol%), or may be in the range of 60 mol% to 95 mol% (for example, the range of 75 mol% to 95 mol%). Here, the oxyC _2-4 alkylene unit may be an oxyethylene unit and / or an oxypropylene unit.

The polyol may be any of an aliphatic polyol, an alicyclic polyol, an aromatic polyol, a heterocyclic polyol and the like. From the viewpoint that the polymer compound (P) is thin and easily spreads on the lead surface, an aliphatic polyol, an alicyclic polyol (for example, polyhydroxycyclohexane, polyhydroxynorbornane, etc.) and the like are preferable, and an aliphatic polyol is particularly preferable. Examples of the aliphatic polyol include an aliphatic diol, a polyol having a triol or higher (for example, glycerin, trimethylolpropane, pentaerythritol, sugar or a sugar alcohol, etc.). Examples of the aliphatic diol include alkylene glycols having 5 or more carbon atoms. The alkylene glycol may be, for example, C _{5-14 alkylene glycol or C 5-10 alkylene} glycol. Examples of the sugar or sugar alcohol include sucrose, erythritol, xylitol, mannitol, sorbitol and the like. The sugar or sugar alcohol may have either a chain structure or a cyclic structure. In the polyalkylene oxide adduct of the polyol, the alkylene oxide corresponds to the _{oxyC 2-4} alkylene unit of the polymer compound (P) and contains at least C _2-4 alkylene oxide. From the viewpoint that the polymer compound (P) can easily form a linear structure, the polyol is preferably a diol.

The etherified product is composed of a -OH group (a hydrogen atom of the terminal group and an oxygen atom bonded to the hydrogen atom of the terminal group) at least a part of the hydroxy compound having a repeating structure of the above oxyC _2-4 alkylene unit. The —OH group) has ^two etherified —OR groups (in the formula, R ² is an organic group). Of the ends of the polymer compound (P), some ends may be etherified, or all ends may be etherified. For example, one end of the main chain of the linear polymer compound (P) may be an −OH group, and the other end may be an ^−OR2 group.

The esterified product is composed of an OH group (a hydrogen atom of the terminal group and an oxygen atom bonded to the hydrogen atom of the terminal group) at least a part of the hydroxy compound having a repeating structure of the _{oxyC 2-4} alkylene unit. The OH group) has ³ esterified —OC (= O) —R groups (in the formula, R ³ is an organic group). Of the ends of the polymer compound (P), some ends may be esterified, or all ends may be esterified. For example, one end of the main chain of the linear polymer compound (P) may be an −OH group, and the other end may be an —OC ⁽ = O) —R3 group.

Examples of the organic groups R ² and R ³ include hydrocarbon groups. The hydrocarbon group may have a substituent (eg, a hydroxy group, an alkoxy group, and / or a carboxy group). The hydrocarbon group may be any of an aliphatic, alicyclic, and aromatic group. The aromatic hydrocarbon group and the alicyclic hydrocarbon group may have an aliphatic hydrocarbon group (for example, an alkyl group, an alkenyl group, an alkynyl group, etc.) as a substituent. The number of carbon atoms of the aliphatic hydrocarbon group as a substituent may be, for example, 1 to 30, 1 to 20, 1 to 10, and 1 to 6 or 1 to 4. May be.

Examples of the aromatic hydrocarbon group include an aromatic hydrocarbon group having 24 or less carbon atoms (for example, 6 to 24). The number of carbon atoms of the aromatic hydrocarbon group may be 20 or less (for example, 6 to 20), 14 or less (for example, 6 to 14) or 12 or less (for example, 6 to 12). Examples of the aromatic hydrocarbon group include an aryl group and a bisaryl group. Examples of the aryl group include a phenyl group and a naphthyl group. Examples of the bisaryl group include a monovalent group corresponding to bisarene. Examples of the bisarene include biphenyl and bisarylalkane (for example, _bisC 6-10aryl C _1-4 alkane (for example, 2,2-bisphenylpropane)).

Examples of the alicyclic hydrocarbon group include an alicyclic hydrocarbon group having 16 or less carbon atoms. The alicyclic hydrocarbon group may be a crosslinked cyclic hydrocarbon group. The alicyclic hydrocarbon group may have 10 or less or 8 or less carbon atoms. The alicyclic hydrocarbon group has, for example, 5 or more carbon atoms, and may be 6 or more carbon atoms.

The number of carbon atoms of the alicyclic hydrocarbon group may be 5 (or 6) or more and 16 or less, 5 (or 6) or more and 10 or less, or 5 (or 6) or more and 8 or less.

Examples of the alicyclic hydrocarbon group include a cycloalkyl group (cyclopentyl group, cyclohexyl group, cyclooctyl group, etc.), a cycloalkenyl group (cyclohexenyl group, cyclooctenyl group, etc.) and the like. The alicyclic hydrocarbon group also includes the hydrogenated additive of the above aromatic hydrocarbon group.

Of the hydrocarbon groups, an aliphatic hydrocarbon group is preferable from the viewpoint that the polymer compound (P) is thinly adhered to the lead surface. Aliphatic hydrocarbon groups may be saturated or unsaturated. Examples of the aliphatic hydrocarbon group include an alkyl group, an alkenyl group, an alkynyl group, a dienyl group having two carbon-carbon double bonds, and a trienyl group having three carbon-carbon double bonds. The aliphatic hydrocarbon group may be linear or branched.

The aliphatic hydrocarbon group may have, for example, 30 or less, 26 or less or 22 or less, 20 or less or 16 or less, 14 or less or 10 or less. It may be 8 or less or 6 or less. The lower limit of the number of carbon atoms is 1 or more for an alkyl group, 2 or more for an alkenyl group and an alkynyl group, 3 or more for a dienyl group, and 4 or more for a trienyl group, depending on the type of the aliphatic hydrocarbon group. From the viewpoint that the polymer compound (P) is thin and easily adheres to the lead surface, an alkyl group or an alkenyl group is particularly preferable.

Specific examples of the alkyl group include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl, neopentyl, i-pentyl, and s-pentyl. 3-Pentyl, t-Pentyl, n-hexyl, 2-ethylhexyl, n-octyl, n-nonyl, n-decyl, i-decyl, undecyl, lauryl (dodecyl), tridecyl, myristyl, pentadecyl, cetyl, heptadecyl, stearyl. , Ikosil, Henikosil, Behenil and the like.

Specific examples of the alkenyl group include vinyl, 1-propenyl, allyl, cis-9-heptadecene-1-yl, palmitrail, oleyl and the like. The alkenyl group may be, for example, a C _2-30 alkenyl group or a C _2-26 alkenyl group, a C _2-22 alkenyl group or a C _2-20 alkenyl group, and a C _10-20 alkenyl group. May be.

The polymer compound (P) is selected from the group consisting of an etherified product of a hydroxy compound having a repeating structure of an _{oxyC 2-4 alkylene unit and an esterified product of a hydroxy compound having a repeating structure of an oxy C 2-4 alkylene} unit. It is preferable to use at least one of them because the effect of suppressing the decrease in charge acceptability can be further enhanced. Further, even when these polymer compounds (P) are used, the amount of overcharge electricity can be reduced. Further, among such polymer compounds (P), those having a repeating structure of an oxypropylene unit, those having a repeating structure of an oxyethylene unit, and the like are preferable.

The polymer compound (P) may have one or more hydrophobic groups. Examples of the hydrophobic group include aromatic hydrocarbon groups, alicyclic hydrocarbon groups, and long-chain aliphatic hydrocarbon groups among the above-mentioned hydrocarbon groups. Examples of the long-chain aliphatic hydrocarbon group include those having 8 or more carbon atoms among the above-mentioned aliphatic hydrocarbon groups (alkyl group, alkenyl group, etc.), preferably 12 or more, and more preferably 16 or more. Among them, the polymer compound (P) having a long-chain aliphatic hydrocarbon group is preferable because it is unlikely to cause excessive adsorption to lead and the effect of suppressing a decrease in charge acceptability is further enhanced. In the polymer compound (P), at least one of the hydrophobic groups may be a long-chain aliphatic hydrocarbon group. The carbon number of the long-chain aliphatic hydrocarbon group may be 30 or less, 26 or less, or 22 or less.

The number of carbon atoms of a long-chain aliphatic hydrocarbon group is 8 or more (or 12 or more) 30 or less, 8 or more (or 12 or more) 26 or less, 8 or more (or 12 or more) 22 or less, 10 or more and 30 or less (or 26 or less). ), Or it may be 10 or more and 22 or less.

Among the polymer compounds (P), those having a hydrophilic group and a hydrophobic group correspond to a nonionic surfactant. The repeating structure of the oxyethylene unit exhibits high hydrophilicity and can be a hydrophilic group in nonionic surfactants. Therefore, it is preferable that the polymer compound (P) having a hydrophobic group described above contains a repeating structure of an oxyethylene unit. Due to the balance between hydrophobicity and high hydrophilicity due to the repeating structure of the oxyethylene unit, such a polymer compound (P) selectively adsorbs lead, but excessively covers the surface of lead. Since it can be suppressed, the effect of suppressing the decrease in charge acceptability can be further enhanced while reducing the amount of overcharged electricity. Such a polymer compound (P) can ensure high adsorptivity to lead even if it has a relatively low molecular weight (for example, Mn is 1000 or less).

Among the above polymer compounds (P), a polyoxypropylene-polyoxyethylene block copolymer, an etherified product of a hydroxy compound having a repeating structure of an oxyethylene unit, an esterified product of a hydroxy compound having a repeating structure of an oxyethylene unit, and the like. Corresponds to a nonionic surfactant.

Examples of the polymer compound (P) having a hydrophobic group and containing a repeating structure of an oxyethylene unit include an etherified product of polyethylene glycol (alkyl ether and the like), an esterified product of polyethylene glycol (carboxylic acid ester and the like), and polyethylene of the above-mentioned polyol. Examples thereof include an etherified product of an oxide adduct (alkyl ether and the like), an esterified product of a polyethylene oxide adduct of the above-mentioned polyol (polyol and higher polyol, etc.) (carboxylic acid ester and the like), and the like. Specific examples of such a polymer compound (P) include polyethylene glycol oleate, polyethylene glycol dioleate, polyethylene glycol dilaurate, polyethylene glycol distearate, polyoxyethylene coconut oil fatty acid sorbitan, polyoxyethylene sorbitan oleate, and stearer. Examples thereof include, but are not limited to, polyoxyethylene sorbitan acid, polyoxyethylene lauryl ether, polyoxyethylene tetradecyl ether, and polyoxyethylene cetyl ether. Above all, it is preferable to use an esterified product of polyethylene glycol, an esterified product of the polyethylene oxide adduct of the above-mentioned polyol, or the like because higher charge acceptability can be ensured and the amount of overcharged electricity can be remarkably reduced.

From the viewpoint that the effect of reducing the amount of overcharged electricity is further enhanced and it is easy to secure higher charge acceptability, it is also preferable that the repeating structure of the _{oxyC 2-4} alkylene includes at least the repeating structure of the oxypropylene unit. In this case, the charge acceptability tends to be lower than in the case of the repeating structure of the oxyethylene unit, but even in this case, high charge acceptability should be ensured while keeping the amount of overcharge electricity low. Can be done. The polymer compound (P) containing the oxypropylene unit has a peak derived from -CH <and -CH _2- of the oxypropylene unit in the range of 3.2 ppm to 3.8 ppm in the chemical shift of ¹ H-NMR spectrum. Have. Since the electron densities around the nuclei of hydrogen atoms in these groups are different, the peaks are split. Such a polymer compound (P) peaks in, for example, a range of 3.2 ppm or more and 3.42 ppm or less and a range of more than 3.42 ppm and 3.8 ppm or less in a chemical shift of ¹ H-NMR spectrum. Has. Peaks in the range of 3.2 ppm or more and 3.42 ppm or less are derived from -CH _2- , and peaks in the range of more than 3.42 ppm and 3.8 ppm or less are derived from -CH <and -CH _2- .

Examples of the polymer compound (P) containing at least the repeating structure of the oxypropylene unit include polypropylene glycol, a copolymer containing the repeating structure of the oxypropylene unit, a polypropylene oxide adduct of the above-mentioned polyol, an etherified product or an esterified product thereof. Can be mentioned. Examples of the copolymer include an oxypropylene-oxyalkylene copolymer (however, the oxyalkylene is C _2-4 alkylene other than oxypropylene). Examples of the oxypropylene-oxyalkylene copolymer include an oxypropylene-oxyethylene copolymer and an oxypropylene-oxytrimethylene copolymer. The oxypropylene-oxyalkylene copolymer may be referred to as a polyoxypropylene-polyoxyalkylene copolymer (for example, a polyoxypropylene-polyoxyethylene copolymer). The oxypropylene-oxyalkylene copolymer may be a block copolymer (for example, a polyoxypropylene-polyoxyethylene block copolymer). Examples of the etherified product include polypropylene glycol alkyl ether, alkyl ether of an oxypropylene-oxyalkylene copolymer (alkyl ether of a polyoxypropylene-polyoxyethylene copolymer, etc.) and the like. Examples of the esterified product include a polypropylene glycol ester of a carboxylic acid and a carboxylic acid ester of an oxypropylene-oxyalkylene copolymer (such as a carboxylic acid ester of a polyoxypropylene-polyoxyethylene copolymer).

Examples of the polymer compound (P) containing at least the repeating structure of the oxypropylene unit include polypropylene glycol, polyoxypropylene-polyoxyethylene copolymer (polyoxypropylene-polyoxyethylene block copolymer, etc.), polypropylene glycol alkyl. Ether (alkyl ether (methyl ether, ethyl ether, butyl ether, etc.) in which R ² is an alkyl having 10 or less carbon atoms (or 8 or less or 6 or less)), polyoxyethylene-polyoxypropylene alkyl ether (R ² above) Is an alkyl having 10 or less carbon atoms (or 8 or less or 6 or less), such as alkyl ether (butyl ether, hydroxyhexyl ether, etc.), polypropylene glycol carboxylate (R ³ above has 10 or less carbon atoms (or 8 or less or 6 or less). ), Polypropylene glycol carboxylate (polypropylene glycol acetate, etc.), which is an alkyl carboxylate, and polypropylene oxide adducts of triol or higher polyols (polypropylene oxide adducts of glycerin, etc.). However, the polymer compound (P) is not limited to these.

In the polymer compound (P) containing the repeating structure of the oxypropylene unit, the proportion of the oxypropylene unit is, for example, 5 mol% or more, and may be 10 mol% or more or 20 mol% or more. The proportion of the oxypropylene unit is, for example, 100 mol% or less. In the above copolymer, the proportion of the oxypropylene unit may be 90 mol% or less, 75 mol% or less, 60 mol% or less, 50 mol% or less, or 43 mol% or less.

In the polymer compound (P) containing the repeating structure of the oxypropylene unit, the proportion of the oxypropylene unit is 5 mol% or more and 100 mol% or less (or 90 mol% or less), 10 mol% or more and 100 mol% or less (or 90 mol% or less), 20 mol%. 100 mol% or less (or 90 mol% or less), 5 mol% or more and 75 mol% or less (or 60 mol% or less), 10 mol% or more and 75 mol% or less (or 60 mol% or less), 20 mol% or more and 75 mol% or less (or 60 mol% or less), It may be 5 mol% or more and 50 mol% or less (or 43 mol% or less), 10 mol% or more and 50 mol% or less (or 43 mol% or less), or 20 mol% or more and 50 mol% or less (or 43 mol% or less).

The polymer compound (P) preferably contains a large amount of _{oxyC 2-4} alkylene unit from the viewpoint of increasing the adsorptivity to lead and facilitating the formation of a linear structure. Such a polymer compound (P) contains, for example, an oxygen atom bonded to a terminal group and an -CH ₂ -group and / or -CH <group bonded to the oxygen atom. In the ¹ H-NMR spectrum of the polymer compound (P), the integrated value V ₁ of the peak of 3.2 ppm to 3.8 ppm occupies a large proportion of the total V _SUM of the integrated value of the predetermined peak. Here, the total V _SUM of the integrated values of the peaks is the sum of the integrated values V ₁ and the integrated values of the peaks of -CH ₂ -group hydrogen atoms and the integrated value of the peaks of -CH <group hydrogen atoms. be. This ratio is, for example, 50% or more, and may be 80% or more. From the viewpoint that the effect of reducing the amount of overcharged electricity is further enhanced and it is easy to secure higher charge acceptability, the above ratio is preferably 85% or more, and more preferably 90% or more. For example, when the polymer compound (P) has a -OH group at the terminal and has a -CH ₂ -group or -CH <group bonded to the oxygen atom of this -OH group, ¹ in the H-NMR spectrum, -CH. The peaks of hydrogen atoms of ₂ -group and -CH <group are in the range of chemical shift exceeding 3.8 ppm and 4.0 ppm or less.

The negative electrode material may contain one kind of polymer compound (P), or may contain two or more kinds.

The polymer compound (P) may contain, for example, a compound having Mn of 5 million or less, a compound of 3 million or less or 2 million or less, a compound of 500,000 or less or 100,000 or less, and 50,000. It may contain the following compounds or compounds of 20000 or less. From the viewpoint of ensuring higher charge acceptability, the polymer compound (P) preferably contains a compound having a Mn of 10,000 or less, and may contain a compound of 5000 or less or 4000 or less, and a compound of 3000 or less or 2500 or less. May include. The Mn of such a compound may be 300 or more, 400 or more, or 500 or more. From the viewpoint of further enhancing the effect of reducing the amount of overcharged electricity, the Mn of such a compound is preferably 1000 or more, and more preferably 1500 or more or 1800 or more. As the polymer compound (P), two or more kinds of compounds having different Mns may be used. That is, the polymer compound (P) may have a plurality of Mn peaks in the molecular weight distribution.

The Mn of the above compound is 300 or more (or 400 or more) 5 million or less, 300 or more (or 400 or more) 3 million or less, 300 or more (or 400 or more) 2 million or less, 300 or more (or 400 or more) 500,000 or less. , 300 or more (or 400 or more) 100,000 or less, 300 or more (or 400 or more) 50,000 or less, 300 or more (or 400 or more) 20000 or less, 300 or more (or 400 or more) 10000 or less, 300 or more (or 400 or more) 5000 Below, 300 or more (or 400 or more) 4000 or less, 300 or more (or 400 or more) 3000 or less, 300 or more (or 400 or more) 2500 or less, 500 or more (or 1000 or more) 5 million or less, 500 or more (or 1000 or more) 3 million or less, 500 or more (or 1000 or more) 2 million or less, 500 or more (or 1000 or more) 500,000 or less, 500 or more (or 1000 or more) 100,000 or less, 500 or more (or 1000 or more) 50,000 or less, 500 or more ( Or 1000 or more) 20000 or less, 500 or more (or 1000 or more) 10000 or less, 500 or more (or 1000 or more) 5000 or less, 500 or more (or 1000 or more) 4000 or less, 500 or more (or 1000 or more) 3000 or less, 500 or more (or 500 or more) Or 1000 or more) 2500 or less, 1500 or more (or 1800 or more) 5 million or less, 1500 or more (or 1800 or more) 3 million or less, 1500 or more (or 1800 or more) 2 million or less, 1500 or more (or 1800 or more) 500,000 or less 1500 or more (or 1800 or more) 100,000 or less, 1500 or more (or 1800 or more) 50,000 or less, 1500 or more (or 1800 or more) 20000 or less, 1500 or more (or 1800 or more) 10,000 or less, 1500 or more (or 1800 or more) 5000 Below, it may be 1500 or more (or 1800 or more) 4000 or less, 1500 or more (or 1800 or more) 3000 or less, or 1500 or more (or 1800 or more) 2500 or less.

The content of the polymer compound (P) in the entire negative electrode material is, for example, 8 ppm or more and may be 10 ppm or more on a mass basis. From the viewpoint of further enhancing the effect of reducing the amount of overcharged electricity, the content of the polymer compound (P) in the entire negative electrode material is preferably 20 ppm or more, more preferably 30 ppm or more on a mass basis. .. The content of the polymer compound (P) in the entire negative electrode material is, for example, 1000 ppm or less, may be less than 1000 ppm, may be 700 ppm or less, and may be 600 ppm or less or 500 ppm or less on a mass basis. You may. From the viewpoint of easily ensuring higher charge acceptability, the content of the polymer compound (P) in the entire negative electrode material is preferably 400 ppm or less, more preferably 300 ppm or less, and 200 ppm or less or 160 ppm or less on a mass basis. It may be 150 ppm or less, 120 ppm or less, or 100 ppm or less.

The content (mass basis) of the polymer compound (P) in the entire negative electrode material is 8 ppm or more (or 10 ppm or more) 1000 ppm or less, 8 ppm or more (or 10 ppm or more) less than 1000 ppm, 8 ppm or more (or 10 ppm or more) 700 ppm or less. , 8ppm or more (or 10ppm or more) 600ppm or less, 8ppm or more (or 10ppm or more) 500ppm or less, 8ppm or more (or 10ppm or more) 400ppm or less, 8ppm or more (or 10ppm or more) 300ppm or less, 8ppm or more (or 10ppm or more) 200ppm or less , 8 ppm or more (or 10 ppm or more) 160 ppm or less, 8 ppm or more (or 10 ppm or more) 150 ppm or less, 8 ppm or more (or 10 ppm or more) 120 ppm or less, 8 ppm or more (or 10 ppm or more) 100 ppm or less, 20 ppm or more (or 30 ppm or more) 1000 ppm or less , 20ppm or more (or 30ppm or more) less than 1000ppm, 20ppm or more (or 30ppm or more) 700ppm or less, 20ppm or more (or 30ppm or more) 600ppm or less, 20ppm or more (or 30ppm or more) 500ppm or less, 20ppm or more (or 30ppm or more) 400ppm or less , 20ppm or more (or 30ppm or more) 300ppm or less, 20ppm or more (or 30ppm or more) 200ppm or less, 20ppm or more (or 30ppm or more) 160ppm or less, 20ppm or more (or 30ppm or more) 150ppm or less, 20ppm or more (or 30ppm or more) 120ppm or less , Or 20 ppm or more (or 30 ppm or more) and 100 ppm or less.

(Organic shrinkage agent)
Organic shrinkage proofing agents are usually roughly classified into lignin compounds and synthetic organic shrinkage proofing agents. It can be said that the synthetic organic shrinkage proofing agent is an organic shrinkage proofing agent other than the lignin compound. Examples of the organic shrinkage proofing agent contained in the negative electrode electrode material include lignin compounds and synthetic organic shrinkage proofing agents. The negative electrode electrode material may contain one kind of organic shrinkage proofing agent, or may contain two or more kinds of organic shrinkage proofing agents. As the organic shrinkage proofing agent, a known organic shrinkage proofing agent used in a lead storage battery may be used.

Examples of the lignin compound include lignin and lignin derivatives. Examples of the lignin derivative include lignin sulfonic acid or a salt thereof (alkali metal salt (sodium salt, etc.), etc.).

The synthetic organic shrinkage proofing agent is an organic polymer containing a sulfur element, and generally contains a plurality of aromatic rings in the molecule and also contains a sulfur element as a sulfur-containing group. Among the sulfur-containing groups, a sulfonic acid group or a sulfonyl group, which is a stable form, is preferable. The sulfonic acid group may be present in acid form or may be present in salt form such as Na salt.

As the organic shrinkage proofing agent, a condensate containing at least a unit of an aromatic compound may be used. Examples of such a condensate include a condensate of an aromatic compound made of an aldehyde compound (such as at least one selected from the group consisting of aldehydes (eg, formaldehyde) and condensates thereof). The organic shrinkage proofing agent may contain a unit of one kind of aromatic compound, or may contain a unit of two or more kinds of aromatic compounds.
The unit of the aromatic compound means a unit derived from the aromatic compound incorporated in the condensate. As the aromatic compound, bisphenol A, bisphenol S, bisphenol F and the like are preferable.

Among the above-mentioned organic shrinkage proofing agents, the negative electrode electrode material may contain, for example, an organic shrinkage proofing agent (first organic shrinkage proofing agent) having a sulfur element content of 2000 μmol / g or more. Examples of the first organic shrinkage proofing agent include the above-mentioned synthetic organic shrinkage proofing agent (the above-mentioned condensate and the like).

The sulfur element content of the first organic shrinkage proofing agent may be 2000 μmol / g or more, and preferably 3000 μmol / g or more. The upper limit of the sulfur element content of the organic shrinkage proofing agent is not particularly limited, but from the viewpoint of further enhancing the effect of reducing the amount of overcharged electricity, it is preferably 9000 μmol / g or less, and more preferably 8000 μmol / g or less.

Even if the sulfur element content of the first organic shrinkage proofing agent is, for example, 2000 μmol / g or more (or 3000 μmol / g or more) 9000 μmol / g or less, or 2000 μmol / g or more (or 3000 μmol / g or more) 8000 μmol / g or less. good.

The first organic shrinkage proofing agent contains a condensate containing a unit of an aromatic compound having a sulfur-containing group, and the condensate may contain at least a unit of a bisphenol compound as a unit of the aromatic compound.

The weight average molecular weight (Mw) of the first organic shrinkage proofing agent is preferably 7,000 or more. The Mw of the first organic shrinkage proofing agent is, for example, 100,000 or less, and may be 20,000 or less.

The negative electrode material can contain, for example, an organic shrinkage proofing agent (second organic shrinkage proofing agent) having a sulfur element content of less than 2000 μmol / g. Examples of the second organic shrinkage proofing agent include lignin compounds and synthetic organic shrinkage proofing agents (particularly, lignin compounds) among the above-mentioned organic shrinkage proofing agents. The sulfur element content of the second organic shrinkage proofing agent is preferably 1000 μmol / g or less, and may be 800 μmol / g or less. The lower limit of the sulfur element content in the second organic shrinkage proofing agent is not particularly limited, but is, for example, 400 μmol / g or more.

The Mw of the second organic shrinkage proofing agent is, for example, less than 7000. The Mw of the second organic shrinkage proofing agent is, for example, 3000 or more.

The negative electrode electrode material may contain a second organic shrinkage proofing agent in addition to the first organic shrinkage proofing agent. When the first organic shrinkage proofing agent and the second organic shrinkage proofing agent are used in combination, the mass ratios thereof can be arbitrarily selected.

The content of the organic shrinkage-proofing agent contained in the negative electrode electrode material is, for example, 0.005% by mass or more, and may be 0.01% by mass or more. When the content of the organic shrinkage proofing agent is in such a range, a high low temperature and high rate discharge capacity can be secured. The content of the organic shrinkage proofing agent is, for example, 1.0% by mass or less, and may be 0.5% by mass or less. From the viewpoint of further enhancing the effect of suppressing the decrease in charge acceptability, the content of the organic shrinkage proofing agent is preferably 0.3% by mass or less, more preferably 0.25% by mass or less, 0.2% by mass or less, or It is more preferably 0.15% by mass or less, and may be 0.12% by mass or less.

The content of the organic shrinkage barrier contained in the negative electrode electrode material is 0.005% by mass or more (or 0.01% by mass) 1.0% by mass or less, 0.005% by mass or more (or 0.01% by mass). (More than) 0.5% by mass or less, 0.005% by mass or more (or 0.01% by mass or more) 0.3% by mass or less, 0.005% by mass or more (or 0.01% by mass or more) 0.25% by mass % Or less, 0.005% by mass or more (or 0.01% by mass or more) 0.2% by mass or less, 0.005% by mass or more (or 0.01% by mass or more) 0.15% by mass or less, or 0. It may be 005% by mass or more (or 0.01% by mass or more) and 0.12% by mass or less.

(Carbonaceous material)
As the carbonaceous material contained in the negative electrode electrode material, carbon black, graphite, hard carbon, soft carbon and the like can be used. Examples of carbon black include acetylene black, furnace black, and lamp black. Furness Black also includes Ketjen Black (trade name). The graphite may be any carbonaceous material containing a graphite-type crystal structure, and may be either artificial graphite or natural graphite. The negative electrode material may contain one kind of carbonaceous material, or may contain two or more kinds of carbonaceous material.

The content of the carbonaceous material in the negative electrode electrode material is, for example, 0.05% by mass or more, and may be 0.10% by mass or more. The content of the carbonaceous material is, for example, 5% by mass or less, and may be 3% by mass or less.

The content of the carbonaceous material in the negative electrode material is 0.05% by mass or more and 5% by mass or less, 0.05% by mass or more and 3% by mass or less, 0.10% by mass or more and 5% by mass or less, or 0.10. It may be mass% or more and 3 mass% or less.

(Barium sulfate)
The content of barium sulfate in the negative electrode electrode material is, for example, 0.05% by mass or more, and may be 0.10% by mass or more. The content of barium sulfate in the negative electrode electrode material is, for example, 3% by mass or less, and may be 2% by mass or less.

The content of barium sulfate in the negative electrode material is 0.05% by mass or more and 3% by mass or less, 0.05% by mass or more and 2% by mass or less, 0.10% by mass or more and 3% by mass or less, or 0.10% by mass. It may be% or more and 2% by mass or less.

(Analysis of negative electrode material or constituents)
The method of analyzing the negative electrode material or its constituent components will be described below. Prior to measurement or analysis, a fully charged lead-acid battery is disassembled to obtain a negative electrode plate to be analyzed. The obtained negative electrode plate is washed with water to remove sulfuric acid from the negative electrode plate. Wash with water by pressing the pH test paper against the surface of the negative electrode plate washed with water until it is confirmed that the color of the test paper does not change. However, the time for washing with water shall be within 2 hours. The negative electrode plate washed with water is dried at 60 ± 5 ° C. for about 6 hours in a reduced pressure environment. If the negative electrode plate contains a sticking member, the sticking member is removed as necessary. Next, a sample (hereinafter referred to as sample A) is obtained by separating the negative electrode material from the negative electrode plate. Sample A is pulverized as needed and subjected to analysis. When measuring the content of the polymer compound (P) in a specific portion in the thickness direction of the negative electrode plate, the material for measurement may be obtained from the portion.

(1) Analysis of polymer compound (P) (1-1) Qualitative analysis of polymer compound (P) Grinded sample A is used. 150.0 ± 0.1 mL of chloroform is added to 100.0 ± 0.1 g of sample A, and the mixture is stirred at 20 ± 5 ° C. for 16 hours to extract the polymer compound (P). Then, the solid content is removed by filtration. Infrared spectroscopy, ultraviolet-visible absorption spectrum, NMR spectrum, LC-MS and heat of the chloroform solution in which the polymer compound (P) obtained by extraction is dissolved or the polymer compound (P) obtained by drying the chloroform solution. The polymer compound (P) is identified by obtaining information from at least one selected from the degraded GC-MS.

Chloroform-soluble components are recovered from the chloroform solution in which the polymer compound (P) obtained by extraction is dissolved by distilling off chloroform under reduced pressure. The chloroform-soluble component is dissolved in deuterated chloroform, and the ¹ H-NMR spectrum is measured under the following conditions. From this ¹ H-NMR spectrum, a peak with a chemical shift in the range of 3.2 ppm or more and 3.8 ppm or less is confirmed. Further, the type of _{oxyC 2-4} alkylene unit is specified from the peak in this range.

Device: AL400 type nuclear magnetic resonance device manufactured by JEOL Ltd. Observation frequency: 395.88 MHz
Pulse width: 6.30 μs
Pulse repetition time: 74.1411 seconds Total number of times: 32
Measurement temperature: Room temperature (20-35 ° C)
Criteria: 7.24 ppm
Sample tube diameter: 5 mm

¹ From the 1 H-NMR spectrum, the integral value (V ₁ ) of the peaks in which the chemical shift exists in the range of 3.2 ppm or more and 3.8 ppm or less is obtained. Further, for each of the hydrogen atoms of -CH ₂ -group and -CH <group bonded to the oxygen atom bonded to the terminal group of the polymer compound (P), the sum of the integrated values of the peaks in the ¹ H-NMR spectrum (1). Find V ₂ ). Then, from V ₁ and V ₂ , the ratio of V ₁ to the total of V ₁ and V ₂ (= V ₁ / (V ₁ + V ₂ ) × 100 (%)) is obtained.

In the qualitative analysis, when the integral value of the peak in the ¹ H-NMR spectrum is obtained, two points in the ¹ H-NMR spectrum having no significant signal so as to sandwich the corresponding peak are determined, and these two points are determined. Each integrated value is calculated using the straight line connecting the intervals as the baseline. For example, for a peak in which the chemical shift is in the range of 3.2 ppm to 3.8 ppm, the straight line connecting the two points of 3.2 ppm and 3.8 ppm in the spectrum is used as the baseline. For example, for a peak in which the chemical shift exceeds 3.8 ppm and exists in the range of 4.0 ppm or less, the straight line connecting the two points of 3.8 ppm and 4.0 ppm in the spectrum is used as the baseline.

(1-2) Quantitative Analysis of Polymer Compound (P) Dissolve an appropriate amount of the above chloroform-soluble component in deuterated chloroform together with _mr (g) tetrachloroethane (TCE) measured with an accuracy of ± 0.0001 g. , 1 Measure the ¹ H-NMR spectrum. The integral value (S _a ) of the peak in which the chemical shift is in the range of 3.2 to 3.8 ppm and the integral value (S _r ) of the peak derived from TCE are obtained, and the polymer compound in the negative electrode electrode material is obtained from the following formula. The mass-based content C _n (ppm) of (P) is determined.

C _n = S _a / S _r × N _r / N _a × _Ma / _{Mr × m r /} m × 1000000
(In the formula, Ma is the molecular weight of the structure in which the chemical shift peaks in the range of 3.2 to 3.8 ppm (more specifically, the molecular weight of the repeating structure of the _{oxyC 2-4} alkylene unit), and N _a is the number of hydrogen atoms bonded to the carbon atom of the main chain of the repeating structure. Nr _{and Mr} are the number of hydrogens contained in the molecule of the reference substance and the molecular weight of the reference substance, respectively, and m (g) is the extraction. It is the mass of the negative electrode material used in.)
Since the reference substance in this analysis is TCE, N _r = 2 and _Mr = 168. Moreover, m = 100.

_For example, when the polymer compound (P) is polypropylene glycol, Ma is 58 and _Na is 3. When the polymer compound (P) is polyethylene glycol, _Ma is 44 and _Na is 4. _Na and _Ma are values obtained by averaging the _Na value and _Ma value of each monomer unit using the molar ratio (mol%) of each monomer unit contained in the repeating structure.

In the quantitative analysis, the integrated value of the peak in the ¹ H-NMR spectrum is obtained by using the data processing software "ALICE" manufactured by JEOL Ltd.

(1-3) Mn measurement of the polymer compound (P) Using the above chloroform-soluble component, GPC measurement of the polymer compound (P) is performed using the following apparatus under the following conditions. Separately, a calibration curve (calibration curve) is created from the plot of Mn of the standard material and the elution time. The Mn of the polymer compound (P) is calculated based on the calibration curve and the GPC measurement result of the polymer compound (P). However, the esterified product or the etherified product may be in a decomposed state in the chloroform-soluble component.

Analysis system: 20A system (manufactured by Shimadzu Corporation)
Column: GPC KF-805L (manufactured by Shodex) connected in series Column temperature: 30 ° C ± 1 ° C
Mobile phase: Tetrahydrofuran Flow rate: 1 mL / min.
Concentration: 0.20% by mass
Injection volume: 10 μL
Standard substance: Polyethylene glycol (Mn = 2,000,000, 200,000, 20,000, 2,000, 200)
Detector: Differential refractometer detector (Shodex RI-201H)

(others)
The negative electrode plate can be formed by applying or filling a negative electrode paste to a negative electrode current collector, aging and drying to produce an unchemical negative electrode plate, and then forming an unchemical negative electrode plate. The negative electrode paste contains, for example, lead powder, a polymer compound (P), and, if necessary, at least one selected from the group consisting of an organic shrinkage proofing agent, a carbonaceous material, and other additives, and water and sulfuric acid ( Alternatively, it is prepared by adding (or sulfuric acid aqueous solution) and kneading. At the time of aging, it is preferable to ripen the unchemical negative electrode plate at a temperature higher than room temperature and high humidity.

The chemical conversion can be carried out by charging the electrode plate group in a state where the electrode plate group including the unchemical negative electrode plate is immersed in the electrolytic solution containing sulfuric acid in the electric tank of the lead storage battery. However, the chemical formation may be performed before assembling the lead-acid battery or the electrode plate group. The formation produces spongy lead.

(Positive plate)
The positive electrode plate of a lead storage battery can be classified into a paste type, a clad type and the like. Either a paste type or a clad type positive electrode plate may be used. The paste type positive electrode plate includes a positive electrode current collector and a positive electrode material. The configuration of the clad type positive electrode plate is as described above.

The positive electrode current collector may be formed by casting lead (Pb) or a lead alloy, or may be formed by processing a lead sheet or a lead alloy sheet. Examples of the processing method include expanding processing and punching processing. It is preferable to use a grid-shaped current collector as the positive electrode current collector because it is easy to support the positive electrode material.

As the lead alloy used for the positive electrode current collector, Pb-Sb-based alloys, Pb-Ca-based alloys, and Pb-Ca-Sn-based alloys are preferable in terms of corrosion resistance and mechanical strength. The positive electrode current collector may include a surface layer. The composition of the surface layer and the inner layer of the positive electrode current collector may be different. The surface layer may be formed on a part of the positive electrode current collector. The surface layer may be formed only on the lattice portion of the positive electrode current collector, only the ear portion, or only the frame bone portion.

The positive electrode material contained in the positive electrode plate contains a positive electrode active material (lead dioxide or lead sulfate) whose capacity is developed by a redox reaction. The positive electrode material may contain other additives, if necessary.

The unchemical paste type positive electrode plate is obtained by filling a positive electrode current collector with a positive electrode paste, aging and drying. The positive electrode paste is prepared by kneading lead powder, additives, water, and sulfuric acid. The unchemical clad type positive electrode plate is formed by filling a porous tube into which a core metal connected at a current collecting part is inserted with lead powder or slurry-like lead powder, and connecting a plurality of tubes in a collective punishment. Will be done. Then, a positive electrode plate is obtained by forming these unchemical positive electrode plates. The chemical conversion can be carried out by charging the electrode plate group in a state where the electrode plate group including the unchemical positive electrode plate is immersed in the electrolytic solution containing sulfuric acid in the electric tank of the lead storage battery. However, the chemical formation may be performed before assembling the lead-acid battery or the electrode plate group.

The chemical conversion can be carried out by charging the electrode plate group in a state where the electrode plate group including the unchemical positive electrode plate is immersed in the electrolytic solution containing sulfuric acid in the electric tank of the lead storage battery. However, the chemical formation may be performed before assembling the lead-acid battery or the electrode plate group.

(Separator)
A separator can be arranged between the negative electrode plate and the positive electrode plate. As the separator, at least one selected from a non-woven fabric and a microporous membrane is used.

Nonwoven fabric is a mat that is entwined without weaving fibers, and is mainly composed of fibers. In the non-woven fabric, for example, 60% by mass or more of the non-woven fabric is formed of fibers. As the fiber, glass fiber, polymer fiber (polyolefin fiber, acrylic fiber, polyester fiber (polyethylene terephthalate fiber, etc.), etc.), pulp fiber, and the like can be used. Of these, glass fiber is preferable. The non-woven fabric may contain components other than fibers, such as an acid-resistant inorganic powder, a polymer as a binder, and the like.

On the other hand, the microporous film is a porous sheet mainly composed of components other than fiber components. For example, a composition containing a pore-forming agent is extruded into a sheet and then the pore-forming agent is removed to form pores. It is obtained by. The microporous membrane is preferably composed of a material having acid resistance, and is preferably composed mainly of a polymer component. As the polymer component, polyolefin (polyethylene, polypropylene, etc.) is preferable. Examples of the pore-forming agent include at least one selected from the group consisting of polymer powders and oils.

The separator may be composed of, for example, only a non-woven fabric or only a microporous membrane. Further, the separator may be a laminate of a non-woven fabric and a microporous film, a material obtained by laminating different or similar materials, or a material in which irregularities are engaged with different or similar materials, as required.

The separator may be in the shape of a sheet or in the shape of a bag. A sheet-shaped separator may be sandwiched between the positive electrode plate and the negative electrode plate. Further, the electrode plate may be arranged so as to sandwich the electrode plate with one sheet-shaped separator in a bent state. In this case, the positive electrode plate sandwiched between the bent sheet-shaped separators and the negative electrode plate sandwiched between the bent sheet-shaped separators may be overlapped, and one of the positive electrode plate and the negative electrode plate may be sandwiched between the bent sheet-shaped separators. , May be overlapped with the other electrode plate. Further, the sheet-shaped separator may be bent in a bellows shape, and the positive electrode plate and the negative electrode plate may be sandwiched between the bellows-shaped separators so that the separator is interposed between them. When a bag-shaped separator is used, the bag-shaped separator may accommodate a positive electrode plate or a negative electrode plate.

(Electrolytic solution)
The electrolytic solution is an aqueous solution containing sulfuric acid, and may be gelled if necessary. The electrolytic solution may contain the above-mentioned polymer compound (P).

The electrolyte may optionally contain cations (eg, metal cations) and / or anions (eg, anions other than sulfate anions (such as phosphate ions)). Examples of the metal cation include at least one selected from the group consisting of Na ion, Li ion, Mg ion, and Al ion.

The specific gravity of the electrolytic solution in the fully charged lead storage battery at 20 ° C. is, for example, 1.20 or more, and may be 1.25 or more. The specific gravity of the electrolytic solution at 20 ° C. is 1.35 or less, preferably 1.32 or less.

The specific gravity of the electrolytic solution at 20 ° C. may be 1.20 or more and 1.35 or less, 1.20 or more and 1.32 or less, 1.25 or more and 1.35 or less, or 1.25 or more and 1.32 or less. ..

(others)
The lead-acid battery can be obtained by a manufacturing method including a step of accommodating a group of plates and an electrolytic solution in a cell chamber of an electric tank. Each cell of the lead-acid battery includes a group of plates and an electrolytic solution housed in each cell chamber. The electrode plate group is assembled by laminating the positive electrode plate, the negative electrode plate, and the separator so that the separator is interposed between the positive electrode plate and the negative electrode plate prior to the accommodation in the cell chamber. The positive electrode plate, the negative electrode plate, the electrolytic solution, and the separator are each prepared prior to assembling the electrode plate group. The method for manufacturing a lead-acid battery may include, if necessary, a step of forming at least one of a positive electrode plate and a negative electrode plate after a step of accommodating a group of electrode plates and an electrolytic solution in a cell chamber.

Each plate in the plate group may be one plate or two or more plates. From the viewpoint of ensuring a high reduction effect of the amount of overcharged electricity, 50% or more (more preferably 80% or more or 90% or more) of the number of negative electrode plates included in the electrode plate group satisfies the above conditions. Is preferable. Among the negative electrode plates included in the electrode plate group, the ratio of those satisfying the above conditions is 100% or less. All of the negative electrode plates included in the electrode plate group may satisfy the above conditions.

When the lead-acid battery has two or more cells, the electrode plate group of at least a part of the cells may be provided with a negative electrode plate satisfying the above conditions. From the viewpoint of ensuring a high reduction effect of the amount of overcharged electricity, 50% or more (more preferably 80% or more or 90% or more) of the number of cells contained in the lead storage battery is a negative electrode plate that satisfies the above conditions. It is preferable to have a group of plates including the plates. Among the cells contained in the lead storage battery, the ratio of the cells including the electrode plate group including the negative electrode plate satisfying the above conditions is 100% or less. It is preferable that all of the electrode plates included in the lead storage battery are provided with a negative electrode plate that satisfies the above conditions.

An example of a lead storage battery according to an embodiment of the present invention will be described below with reference to the drawings. The above description can be applied to the embodiments described below. Further, the embodiments described below may be modified based on the above description. Further, the matters described below may be applied to the above-described embodiment. Further, among the items described below, items that are not essential to the present invention may be omitted.

FIG. 1 shows the appearance of an example of a lead storage battery according to an embodiment of the present invention. The lead-acid battery 1 includes an electric tank 12 for accommodating a plate group 11 and an electrolytic solution (not shown). The inside of the electric tank 12 is partitioned into a plurality of cell chambers 14 by a partition wall 13. One electrode plate group 11 is housed in each cell chamber 14. The opening of the battery case 12 is closed by a lid 15 including a negative electrode terminal 16 and a positive electrode terminal 17. The lid 15 is provided with a liquid spout 18 for each cell chamber. At the time of refilling water, the liquid spout 18 is removed and the refilling liquid is replenished. The liquid spout 18 may have a function of discharging the gas generated in the cell chamber 14 to the outside of the battery.

The electrode plate group 11 is configured by laminating a plurality of negative electrode plates 2 and positive electrode plates 3 via a separator 4, respectively. Here, the bag-shaped separator 4 accommodating the negative electrode plate 2 is shown, but the form of the separator is not particularly limited. In the cell chamber 14 located at one end of the battery case 12, the negative electrode shelf portion 6 for connecting the plurality of negative electrode plates 2 in parallel is connected to the through connection body 8, and the positive electrode shelf portion for connecting the plurality of positive electrode plates 3 in parallel is connected. 5 is connected to the positive electrode column 7. The positive electrode column 7 is connected to the positive electrode terminal 17 outside the lid 15. In the cell chamber 14 located at the other end of the battery case 12, the negative electrode column 9 is connected to the negative electrode shelf portion 6, and the penetration connecting body 8 is connected to the positive electrode shelf portion 5. The negative electrode column 9 is connected to the negative electrode terminal 16 outside the lid 15. Each through-connecting body 8 passes through a through-hole provided in the partition wall 13 and connects the electrode plates 11 of the adjacent cell chambers 14 in series.

The positive electrode shelf portion 5 is formed by welding the selvage portions provided on the upper portions of the positive electrode plates 3 to each other by a cast-on-strap method or a burning method. The negative electrode shelf portion 6 is also formed by welding the selvage portions provided on the upper portions of the negative electrode plates 2 as in the case of the positive electrode shelf portion 5.

The lid 15 of the lead storage battery has a single structure (single lid), but is not limited to the case shown in the illustrated example. The lid 15 may have, for example, a double structure including an inner lid and an outer lid (or upper lid). The lid having a double structure is provided with a recirculation structure between the inner lid and the outer lid for returning the electrolytic solution to the inside of the battery (inside the inner lid) from the recirculation port provided in the inner lid. May be good.

A cross-sectional view of a part of the negative electrode plate 2 of an example is schematically shown in FIG. 2A. A cross-sectional view taken along the line IIB-IIB of FIG. 2A is schematically shown in FIG. 2B. The cross-sectional view of FIG. 2A is a cross-sectional view taken along the line IIA-IIA of FIG. 2B. Note that FIGS. 2A and 2B are schematic views and are different from actual views. For example, when the negative electrode current collector 2a is an expanded lattice, the cross-sectional view as shown in FIGS. 2A and 2B may not be obtained.

The negative electrode plate 2 includes a grid-shaped negative electrode current collector 2a and a negative electrode material 2b supported by the negative electrode current collector 2a. The negative electrode current collector 2a includes a grid portion composed of a plurality of linear portions 2aa. The negative electrode material 2b includes a first negative electrode material (first layered portion) 2b1 and a second negative electrode material 2b2 (second layered portion). The first negative electrode electrode material 2b1 is arranged in a gap (a gap in a lattice portion) between a plurality of linear portions 2aa, and is in contact with the negative electrode current collector 2a. In the example shown in FIG. 2A, the first negative electrode material (first layered portion) 2b1 is sandwiched between two second layered portions (second negative electrode material 2b2) arranged outside the first negative electrode material (first layered portion). .. That is, in the example shown in FIG. 2A, the two second layered portions (second negative electrode material 2b2) sandwich the first layered portion (first negative electrode material 2b1) and the negative electrode current collector 2a. Is located in.

Note that FIG. 2B shows an example in which the boundary between the first negative electrode material 2b1 and the second negative electrode material 2b2 is clear. However, their boundaries do not have to be clear. For example, the content of the polymer compound (P) may gradually decrease from the central portion in the thickness direction of the negative electrode plate 2 toward the surface side of the negative electrode plate 2.

In one example, as shown in FIG. 3, it is also possible to consider the negative electrode material 2b arranged on the negative electrode plate 2 by dividing it into three regions in the thickness direction. In FIG. 3, the negative electrode material 2b is divided into a central first region 2ba and two second regions 2bb on both sides thereof in the thickness direction. In this example, the thicknesses of the two second regions 2bb are equal, but they may be different. In this example, the content of the polymer compound (P) in the central first region 2ba is higher than the content of the polymer compound (P) in the two second regions 2bb on both sides thereof. The negative electrode material constituting the first region 2ba is the first negative electrode material in contact with the negative electrode current collector 2a. The negative electrode material constituting the second region 2bb is a second negative electrode material arranged outside the first negative electrode material. When the thickness of the negative electrode material 2b arranged on the negative electrode plate 2 is T, the thickness T1 of the first region 2ba and the thickness T2 of one second region 2bb are within the above-mentioned ranges. You may.

The two boundaries between the first region 2ba and the second region 2bb may coincide with the surfaces S1 and S2 on both sides of the negative electrode current collector 2a, respectively. Here, the surface S1 is, for example, a metal plate that comes into contact with the negative electrode current collector 2a when a metal plate (for example, a thickness of 1 mm) made of the same material as the negative electrode current collector 2a is pressed against the negative electrode current collector 2a. Equal to the surface. The distance between the surface S1 and the surface S2 can be regarded as the thickness of the negative electrode current collector 2a.

2B and 3 show an example in which the second negative electrode material is arranged outside the two main surfaces of the first negative electrode material. However, the second negative electrode material may be arranged only on the outside of one main surface of the first negative electrode material. That is, one of the two layered second negative electrode materials shown in FIGS. 2B and 3 may not be present. However, the effect obtained is higher when the second negative electrode material having two layers is used.

The method for manufacturing the negative electrode plate 2 as shown in FIGS. 2A, 2B, and 3 is not particularly limited. The first and second examples of the manufacturing method will be described below. In the first example, a negative electrode plate is manufactured using negative electrode pastes having different contents of the polymer compound (P). Specifically, first, a first negative electrode paste containing the polymer compound (P) and a second negative electrode paste having a lower content of the polymer compound (P) than the first negative electrode paste are prepared. Next, the first negative electrode paste is applied to the negative electrode current collector so that the voids of the negative electrode current collector are filled with the first negative electrode paste. Next, the second negative electrode paste is applied to both sides of the negative electrode current collector so as to sandwich the first negative electrode paste. After that, if necessary, processing such as drying is performed. In this way, the negative electrode plate 2 can be manufactured.

The content of the polymer compound (P) in the first negative electrode material by changing the content of the polymer compound (P) in the first negative electrode paste and the content of the polymer compound (P) in the second negative electrode paste. The amount, the content of the polymer compound in the second negative electrode material, and their ratio can be varied.

In the second example, first and second negative electrode pastes are prepared. The first and second negative electrode pastes may or may not contain the polymer compound (P), respectively. Next, the first negative electrode paste is applied to the negative electrode current collector so that the voids of the negative electrode current collector are filled with the first negative electrode paste. Next, the applied first negative electrode paste is dried to form a first electrode material layer. Next, the first electrode material layer is brought into contact with a liquid containing the polymer compound (P). This increases the content of the polymer compound (P) in the first electrode material layer. For example, the first electrode material layer may be immersed in a liquid containing the polymer compound (P). Alternatively, the first electrode material layer may be sprayed with a liquid containing the polymer compound (P). The content of the polymer compound (P) in the finally obtained first negative electrode electrode material can be changed depending on the concentration of the polymer compound (P) in the liquid and the contact time. Next, the second negative electrode paste is applied to both sides of the negative electrode current collector so as to sandwich the first electrode material layer. After that, if necessary, processing such as drying is performed. In this way, the negative electrode plate 2 can be manufactured. In the second example, the magnitude relationship between the content of the polymer (P) in the first negative electrode paste and the content of the polymer compound (P) in the second negative electrode paste is not limited. Finally, the negative electrode plate described above may be manufactured. The step of drying the first negative electrode paste may or may not be performed between the application of the first negative electrode paste and the application of the second negative electrode paste.

The lead-acid batteries according to one aspect of the present invention are summarized below.

(1) Lead-acid battery
Including positive electrode plate and negative electrode plate,
The negative electrode plate contains a negative electrode current collector and a negative electrode material supported by the negative electrode current collector.
The negative electrode material includes a first negative electrode material in contact with the negative electrode current collector and a second negative electrode material arranged outside the first negative electrode material.
The content (ppm) of the polymer compound in the first negative electrode material is higher than the content (ppm) of the polymer compound in the second negative electrode material.
The polymer compound is a lead-acid battery having a peak in the range of 3.2 ppm or more and 3.8 ppm or less in a chemical shift of ¹ H-NMR spectrum measured using deuterated chloroform as a solvent.

(2) Lead-acid battery
Including positive electrode plate and negative electrode plate,
The negative electrode plate contains a negative electrode current collector and a negative electrode material supported by the negative electrode current collector.
The negative electrode material includes a first negative electrode material in contact with the negative electrode current collector and a second negative electrode material arranged outside the first negative electrode material.
The content (ppm) of the polymer compound in the first negative electrode material is higher than the content (ppm) of the polymer compound in the second negative electrode material.
The polymer compound is a lead-acid battery comprising a repeating structure of _{oxyC 2-4} alkylene units.

(3) In the lead-acid battery of (2) above, the polymer compound comprises a hydroxy compound containing the repeating structure of the _{oxyC 2-4} alkylene unit, an etherified product of the hydroxy compound, and an esterified product of the hydroxy compound. It may contain at least one selected from the group.

(4) In the lead-acid battery of the above (2), the polymer compound may contain an esterified product of a polyalkylene glycol having an alkylene group having a carbon number in the range of 2 to 4.

(5) In the lead storage battery according to any one of (1) to (4) above, the negative electrode current collector may include a plurality of linear portions. In that case, the first negative electrode material may be arranged in the gap between the plurality of linear portions.

(6) In the lead storage battery of the above (5), the negative electrode current collector may have a lattice portion composed of the plurality of linear portions.

(7) In the lead-acid batteries of the above (1) to (6), the content (ppm) of the polymer compound in the second negative electrode material is the content of the polymer compound in the first negative electrode material (7). It may be in the range of 0 to 0.7 times (ppm).

(8) In the lead-acid batteries of (1) to (7), the mass-based content of the polymer compound in the first negative electrode material may be in the range of 80 ppm to 500 ppm.

[Example]
Hereinafter, the present invention will be specifically described based on Examples and Comparative Examples, but the present invention is not limited to the following Examples.

<< Lead-acid batteries A1 to A6, C1 to C6, R1 >>
(1) Preparation of lead-acid battery (a) Preparation of negative electrode plate Lead powder as raw material, barium sulfate, carbon black, organic shrink proofing agent (sodium lignin sulfonate), and polymer compound (P) as needed. , Mix with an appropriate amount of sulfuric acid aqueous solution to obtain a first negative electrode paste. The polymer compound (P) is added to the first negative electrode paste so that the content (mass basis) of the polymer compound (P) in the first negative electrode electrode material is the content shown in Table 1. Similarly, the content of the organic shrinkage barrier in the first negative electrode electrode material is 0.1% by mass, the content of barium sulfate is 0.4% by mass, and the content of carbon black is 0.2% by mass. Mix each ingredient in. Sodium lignin sulfonate is used as the organic shrinkage proofing agent.

Next, except that the polymer compound (P) is added so that the content (mass basis) of the polymer compound (P) in the second negative electrode electrode material becomes the content in Table 1, the first negative electrode is used. A second negative electrode paste is prepared in the same manner as the paste. Next, the first negative electrode paste is applied to the negative electrode current collector so that the voids in the lattice portion of the negative electrode current collector are filled with the first negative electrode paste. As the negative electrode current collector, a negative electrode current collector containing an expanded lattice made of a Pb—Ca—Sn alloy is used. Next, the second negative electrode paste is applied to both sides of the expanded lattice so as to sandwich the first negative electrode paste supported by the expanded lattice. Next, the obtained electrode is aged and dried to obtain an unchemical negative electrode plate. The first negative electrode paste becomes the first negative electrode material, and the second negative electrode paste becomes the second negative electrode material.

(B) Preparation of positive electrode plate The lead powder as a raw material is mixed with an aqueous sulfuric acid solution to obtain a positive electrode paste. The positive electrode paste is filled in the mesh portion of the expanded lattice made of Pb—Ca—Sn alloy and aged and dried to obtain an unchemicald positive electrode plate.

(C) Preparation of test battery The test battery has a rated voltage of 2V and a rated 5-hour rate capacity of 32Ah. The electrode plate group of the test battery is composed of seven positive electrode plates and seven negative electrode plates. The negative electrode plate is housed in a bag-shaped separator formed of a microporous polyethylene film, and is alternately laminated with the positive electrode plate to form a group of electrode plates. A group of electrode plates is housed in a polypropylene electric tank together with an electrolytic solution (sulfuric acid aqueous solution) and chemically formed in the electric tank to produce a liquid-type lead-acid battery. The specific gravity of the electrolytic solution in a fully charged lead-acid battery at 20 ° C. is 1.28.

(2) Evaluation (a) Evaluation of overcharged electricity amount Using the above test battery (lead storage battery), the overcharged electricity amount is measured under the following conditions. A 1-minute discharge-10-minute charge test (1-10-minute test) is performed at 75 ° C ± 3 ° C to make the overcharge condition more than the normal 4-minute-10-minute test specified in JIS D5301. (High temperature light load test). In the high temperature light load test, the high temperature light load test is performed by repeating charging and discharging for 1220 cycles. The integrated value (Ah) of the overcharged electricity amount is obtained by summing up the overcharged electricity amount (charged electricity amount-discharged electricity amount) in each cycle up to 1220 cycles. The overcharged electricity amount of each lead storage battery is evaluated at a ratio when the integrated value (Ah) of the overcharged electricity amount of the lead storage battery R1 is 100%.
Discharge: 25A, 1 minute Charge: 2.47V / cell, 25A, 10 minutes Water tank temperature: 75 ° C ± 3 ° C

(B) Low temperature and high rate discharge performance after light load test The test battery after full charge after the high temperature light load test in (a) above has a terminal voltage of 1.0 V / cell at a discharge current of 150 A and -15 ° C. Discharge until it reaches. The discharge time (s) at this time is defined as the discharge duration of the low temperature and high rate discharge after the light load test. The longer the discharge duration, the better the low temperature and high rate discharge performance. The low temperature and high rate discharge performance of each battery is evaluated by the ratio (%) when the discharge duration of the lead storage battery R1 is 100.

(C) Amount of decrease in electrolyte Measure the mass (M ₀ ) of the test battery. The test battery is charged at a constant voltage of 14.4 V at a maximum current of 50 A for 84 days in a water tank at 60 ° C. ± 5 ° C. After charging, the test battery taken out from the water tank is left to room temperature (20 to 35 ° C.), and then the mass (M ₁ ) of the test battery is measured. By subtracting M ₁ from M ₀ , the amount of decrease in the electrolytic solution is obtained. The reduction amount of the electrolytic solution of each battery is evaluated by the ratio (%) when the reduction amount of the electrolytic solution of the battery R1 is 100.

Table 1 shows some of the manufacturing conditions and evaluation results. In Table 1, the "PEG esterified product" is an esterified product of polyethylene glycol, specifically, a polyoxyethylene oleic acid ester. The polyoxyethylene oleic acid ester is a polymer compound represented by C ₁₇ H ₃₃ COO (-CH ₂ -CH ₂ -O) ₅ -H. In Table 1, "PPG" is polypropylene glycol (number average molecular weight is about 2000).

In the batteries A1 to A6, the content of the polymer compound (P) in the first negative electrode material arranged in the center of the negative electrode plate is the content of the polymer compound (P) in the second negative electrode material arranged on the surface of the negative electrode plate. It is higher than the content of the polymer compound (P). On the other hand, in the batteries C1 to C6, the polymer compound (P) is substantially uniformly dispersed in the negative electrode material. The negative electrode material of the battery R1 does not contain the polymer compound (P).

Among the results in Table 1, the result of the amount of overcharged electricity is shown in FIG. 4, and the result of the low temperature and high rate discharge performance after the light load test is shown in FIG. As shown in Table 1 and FIG. 4, when the type of the polymer compound (P) is the same and the content of the polymer compound (P) in the entire negative electrode material is the same, the amount of overcharge electricity of the batteries A1 to A6 is , It is lower than the amount of overcharge electricity of the corresponding batteries C1 to C6. It is considered that this is due to the above-mentioned reason (paragraph 0018). The batteries A1 to A6 and the batteries C1 to C6 to which the polymer compound (P) is added all have a lower amount of overcharge electricity than the battery R1.

As shown in Table 1 and FIG. 5, when the type of the polymer compound (P) is the same and the content of the polymer compound (P) in the entire negative electrode material is the same, the low temperature and high rate discharge performance of the batteries A1 to A6 is performed. Is higher than the low temperature and high rate discharge performance of the corresponding batteries C1 to C6. This is considered to be due to the above-mentioned reason (paragraph 0019). In the batteries A1 to A6, the decrease in the low temperature and high rate discharge performance when the content of the polymer compound (P) in the entire negative electrode is increased is remarkably small as compared with the batteries C1 to C6.

Comparing the batteries A1 to A3 and the batteries A4 to A6, the use of the esterified product of polyethylene glycol has a lower amount of overcharge electricity and higher low-temperature and high-rate discharge performance than that of polypropylene glycol.

A comparison between the batteries A1 to A3 and the batteries C1 to C3, and a comparison between the batteries A5 and the battery C5 are made. When the type of the polymer compound (P) is the same and the content of the polymer compound (P) in the entire negative electrode material is the same, the battery in which the polymer compound (P) is added to the center of the negative electrode plate is more polymer. The amount of liquid reduction (reduction amount of electrolytic solution) was smaller than that of the battery in which the compound was uniformly added to the entire negative electrode plate. Comparing the battery A2 and the battery A5, it is possible to reduce the amount of liquid reduction by using an esterified product of polyethylene glycol rather than polypropylene glycol.

<< Lead-acid batteries A7 and C7 >>
By the same method as that of the lead-acid battery A1 except that the mass-based content of the polymer compound (P) in the first negative electrode material and the second negative electrode material is changed as shown in Table 2. , Batteries A7 and C7 are made. As the polymer compound (P), the same polymer compound used in the battery A1 is used. Table 2 shows some of the manufacturing conditions and evaluation results.

In the battery A7, the content of the polymer compound (P) in the second negative electrode material is about 0.5 times the content of the polymer compound (P) in the first negative electrode material. The amount of overcharged electricity of the battery A7 is lower than the amount of overcharged electricity of the battery C7, and exhibits good characteristics. Further, the low temperature and high rate discharge performance of the battery A7 is better than the low temperature and high rate discharge performance of the battery C7. The amount of decrease in the electrolytic solution of the battery A7 is smaller than the amount of decrease in the electrolytic solution of the battery C7.

As described above, according to the present invention, a lead storage battery having a particularly low amount of overcharged electricity can be obtained. Further, according to the present invention, a lead storage battery having a particularly low amount of overcharge electricity and high low temperature and high rate discharge performance can be obtained.

The present invention can be used for lead storage batteries. The lead-acid battery of the present invention is suitable for use in an idling stop vehicle as, for example, a lead-acid battery for IS that is charged and discharged under PSOC conditions. Further, the lead-acid battery can be suitably used, for example, as a power source for starting a vehicle (automobile, motorcycle, etc.) or an industrial power storage device (for example, a power source for an electric vehicle (forklift, etc.)). It should be noted that these uses are merely examples and are not limited to these uses.

1: Lead storage battery 2: Negative electrode plate 2a: Negative electrode current collector 2aa: Linear part 2b: Negative electrode material 2b1: First negative electrode material 2b2: Second negative electrode material 3: Positive electrode plate 4: Separator 5: Positive electrode Shelf 6: Negative electrode Shelf 7: Positive electrode column 8: Penetration connector 9: Negative electrode column 11: Electrode plate group 12: Electrode tank 13: Partition 14: Cell chamber 15: Lid 16: Negative electrode terminal 17: Positive electrode terminal 18: Liquid Mouth plug

Claims (8)

Including positive electrode plate and negative electrode plate,
The negative electrode plate contains a negative electrode current collector and a negative electrode material supported by the negative electrode current collector.
The negative electrode material includes a first negative electrode material and a second negative electrode material arranged outside the first negative electrode material.
The mass-based content (ppm) of the polymer compound in the first negative electrode material is higher than the mass-based content (ppm) of the polymer compound in the second negative electrode material.
The polymer compound is a lead-acid battery having a peak in the range of 3.2 ppm or more and 3.8 ppm or less in a chemical shift of ¹ H-NMR spectrum measured using deuterated chloroform as a solvent. Including positive electrode plate and negative electrode plate,
The negative electrode plate contains a negative electrode current collector and a negative electrode material supported by the negative electrode current collector.
The negative electrode material includes a first negative electrode material and a second negative electrode material arranged outside the first negative electrode material.
The mass-based content (ppm) of the polymer compound in the first negative electrode material is higher than the mass-based content (ppm) of the polymer compound in the second negative electrode material.
The polymer compound is a lead-acid battery comprising a repeating structure of _{oxyC 2-4} alkylene units. The polymer compound comprises at least one selected from the group consisting of a hydroxy compound containing the repeating structure of the _{oxyC 2-4} alkylene unit, an etherified product of the hydroxy compound, and an esterified product of the hydroxy compound. The lead storage battery according to 2. The lead-acid battery according to claim 2, wherein the polymer compound contains an esterified product of a polyalkylene glycol having an alkylene group having a carbon number in the range of 2 to 4. The negative electrode current collector includes a plurality of linear portions and includes a plurality of linear portions.
The lead-acid battery according to any one of claims 1 to 4, wherein the first negative electrode electrode material is arranged in a gap between the plurality of linear portions. The lead-acid battery according to claim 5, wherein the negative electrode current collector has a lattice portion composed of the plurality of linear portions. The mass-based content (ppm) of the polymer compound in the second negative electrode material is 0 to 0.7 times the mass-based content (ppm) of the polymer compound in the first negative electrode material. The lead-acid battery according to any one of claims 1 to 6, which is in the range. The lead-acid battery according to any one of claims 1 to 7, wherein the content of the polymer compound in the first negative electrode material on a mass basis is in the range of 80 ppm to 500 ppm.

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