JP7533166B2 - Lead-acid battery - Google Patents

Description

The present invention relates to a lead-acid battery.

Lead-acid batteries are used in vehicles, industrial applications, and a variety of other applications. A lead-acid battery typically includes a battery case, negative and positive plates, a separator (or mat), and an electrolyte, all of which are contained in the battery case. The battery case is covered with a lid. The battery case and the lid form an exterior body.

When a lead-acid battery is charged and discharged, the water in the electrolyte may be electrolyzed to generate hydrogen gas and oxygen gas. If these gases are released to the outside of the exterior body, the electrolyte will decrease. Furthermore, when these gases are released to the outside of the exterior body, the water vapor and electrolyte mist contained in these gases may also be released to the outside of the exterior body, which will further reduce the electrolyte. One method of preventing the reduction in electrolyte is to prevent the water vapor and electrolyte mist inside the exterior body from being released to the outside of the exterior body.

Patent Document 1 (JP Patent Publication 2013-004436A) discloses a lead-acid battery that "includes a battery case having an electrolyte therein and a lid that closes the top opening of the battery case, and is characterized in that the inside of the battery case closed by the lid is separated from the outside of the battery case by a functional membrane that allows gas to pass through but prevents liquid from passing through."

Patent Document 2 (International Publication No. WO 2019/097575) discloses "(Claim 1) A lead-acid battery comprising a battery case having a cell chamber and an open top, an electrode group and an electrolyte contained in the cell chamber, and a lid for closing the opening, the electrode group having a plurality of negative electrodes and a plurality of positive electrodes, and the plurality of negative electrodes being connected to each other by a strap formed of an alloy containing Pb and Sn." and "The lead-acid battery according to claim 1, wherein the lid has a first lid portion, a second lid portion provided on the first lid portion, and an exhaust chamber formed between the first lid portion and the second lid portion, and a return hole for returning the electrolyte into the cell chamber is provided in the bottom wall of the first lid portion that separates the exhaust chamber from the cell chamber."

JP 2013-004436 A International Publication No. 2019/097575

In lead-acid batteries, there is a demand to further reduce the amount of electrolyte loss. In this situation, one of the objectives of the present invention is to provide a new lead-acid battery that can reduce the amount of electrolyte loss.

One aspect of the present invention relates to a lead-acid battery, which includes an electrolyte, a plate assembly, and an exterior body, the exterior body including a battery case in which the electrolyte and the plate assembly are housed, and a lid portion disposed at an opening of the battery case, the lid portion including a gas flow passage portion constituting a gas flow passage for discharging gas generated in the battery case to the outside of the exterior body, the lid portion having a circulation structure for sending liquid condensed in the gas flow passage into the battery case, at least one compound selected from the group consisting of compounds having a hydrophilic group and polymer compounds disposed on at least a portion of the surface of the gas flow passage portion, the polymer compound having a peak in the range of 3.2 ppm to 3.8 ppm in chemical shift of a ¹ H-NMR spectrum measured using deuterated chloroform as a solvent.

Another aspect of the present invention relates to another lead-acid battery, which includes an electrolyte, a plate assembly, and an exterior body, the exterior body including a battery case in which the electrolyte and the plate assembly are housed, and a lid portion disposed at an opening of the battery case, the lid portion including a gas flow path portion constituting a gas flow path for discharging gas generated in the battery case to the outside of the exterior body, the lid portion having a circulation structure for sending liquid condensed in the gas flow path into the battery case, and at least one compound selected from the group consisting of compounds having a hydrophilic group and polymer compounds is disposed on at least a portion of the surface of the gas flow path portion, the polymer compound including a repeating structure of oxy-C _2-4 alkylene units.

The present invention provides a lead-acid battery with a small amount of electrolyte loss.

1 is a partially cutaway exploded perspective view showing the appearance and internal structure of a lead-acid battery according to one aspect of the present invention. FIG. FIG. 4 is a top view diagrammatically illustrating an example of a first lid. FIG. 2B is a cross-sectional view taken along line IIB-IIB in FIG. 2A. FIG. 2B is a cross-sectional view taken along line IIC-IIC in FIG. 2A. 1 is a graph showing an example of the results of an example.

The following describes an embodiment of the present invention using 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 are obtained. In this specification, when "numerical value A to numerical value B" is mentioned, the range includes numerical value A and numerical value B.

(Lead-acid battery)
The lead-acid battery according to this embodiment includes an electrolyte, a plate assembly, and an exterior body. The exterior body includes a battery case in which the electrolyte and the plate assembly are accommodated, and a lid portion disposed at an opening of the battery case. The lid portion includes a gas flow passage portion constituting a gas flow passage for discharging gas generated in the battery case to the outside of the exterior body. Furthermore, the lid portion has a circulation structure for sending liquid condensed in the gas flow passage into the battery case. At least one compound selected from the group consisting of a compound having a hydrophilic group and a polymer compound is disposed on at least a part of the surface of the gas flow passage portion. The compound having a hydrophilic group, the polymer compound, and the at least one compound may be referred to as "compound (HC)", "polymer compound (P)", and "compound (C)", respectively, hereinafter.

The first example of the polymer compound (P) is a polymer compound having a peak in the range of 3.2 ppm to 3.8 ppm in the chemical shift of the ¹ H-NMR spectrum measured using deuterated chloroform as a solvent. In this specification, the ¹ H-NMR spectrum is a spectrum measured using deuterated chloroform as a solvent, unless otherwise specified. The second example of the polymer compound (P) is a polymer compound containing a repeating structure of an oxy C _2-4 alkylene unit. The polymer compound included in the first example of the polymer compound (P) and the polymer compound included in the second example of the polymer compound (P) at least partially overlap. The polymer compound (P) may be a commercially available one. Alternatively, the polymer compound (P) may be synthesized by a known method.

As mentioned above, in lead-acid batteries, it is very important to suppress the loss of electrolyte. As a result of their investigation, the inventors of the present application discovered that the loss of electrolyte can be suppressed by placing a specific compound on the surface of the gas flow passage of the lid. The present invention is based on this new finding.

In the lead-acid battery according to this embodiment, compound (C) is arranged in the gas flow passage of the lid. As described in the examples, in the lead-acid battery according to this embodiment, the decrease in electrolyte is suppressed. This is believed to be because compound (C) arranged in the gas flow passage promotes condensation of water vapor and electrolyte mist. This is believed to be because water molecules are more likely to be adsorbed on the surface of the compound having a hydrophilic group in the gas flow passage of the lid, where water vapor and electrolyte mist collide with the wall surface the most. The liquid condensed in the gas flow passage is sent into the battery container by the circulation structure. As a result, the decrease in electrolyte is suppressed.

The total amount of compound (C) placed in the gas flow passage may be in the range of 0.05 mg to 2000 mg (e.g., 1 mg to 1000 mg). By setting the amount in this range, the effect of the present invention can be enhanced.

The negative electrode material of the negative plate in the electrode group may contain a polymer compound (P). By including the polymer compound (P) in the negative electrode material, it is possible to reduce the amount of overcharge electricity. Furthermore, by reducing the amount of overcharge electricity, it is possible to suppress the reduction in the electrolyte.

The reason why the polymer compound (P) can reduce the amount of electricity in overcharge is believed to be as follows. The polymer compound (P) contains a repeating structure of oxy-C _2-4 alkylene units and is therefore likely to have a linear structure. Therefore, the polymer compound (P) added to the negative electrode material thinly and widely covers the surface of the lead in the negative electrode material. By covering the surface of the lead with the polymer compound (P), the hydrogen overvoltage increases, and as a result, a side reaction that generates hydrogen during overcharge is less likely to occur. As a result, the polymer compound (P) can reduce the amount of electricity in overcharge.

When the negative electrode material contains a polymer compound (P), the content of the polymer compound (P) in the negative electrode material may be in the range of 30 ppm to 500 ppm (e.g., in the range of 50 ppm to 200 ppm) by mass. The content may be less than 30 ppm or more than 500 ppm. The content may be in the range of 10 ppm to 1000 ppm (e.g., in the range of 30 ppm to 200 ppm or in the range of 50 ppm to 400 ppm) by mass.

When adding a polymer compound (P) to the negative electrode material, the compound (C) placed in the gas flow passage section and the polymer compound (P) added to the negative electrode material may be different, but it is usually preferable that they are the same. The compound (C) placed in the gas flow passage section may gradually flow into the electrolyte. By making the compound (C) placed in the gas flow passage section and the polymer compound (P) added to the negative electrode material the same, it is possible to obtain the effect of the polymer compound (P) added to the negative electrode material even if the compound (C) flows into the electrolyte. From this viewpoint, it is preferable that the compound (C) placed in the gas flow passage section and the polymer compound (P) added to the negative electrode material are the same.

The material of the lid is not particularly limited, and may be made of a known material. The lid may be made mainly of synthetic resin. At least a portion of the surface of the gas flow path may be made of synthetic resin. 50% or more (area ratio) of the surface of the gas flow path may be made of synthetic resin. The proportion of the surface area of the gas flow path made of synthetic resin may be in the range of 50 to 100% (80 to 100%). Examples of synthetic resins used as the material of the lid include polyethylene, polypropylene, ethylene-propylene copolymer, styrene-acrylonitrile copolymer, polyacrylonitrile-butadiene-styrene resin, etc.

The polymer compound (P) preferably contains a repeating structure of an oxy-C _2-4 alkylene unit. This configuration strengthens the adsorption force of the polymer compound (P) to the surface of the gas flow passage (for example, a surface formed of a synthetic resin). As a result, the polymer compound (P) can be disposed on the surface of the gas flow passage for a long period of time, and the effects of the present invention can be obtained for a long period of time. If the adsorption force of the compound (C) to the surface of the gas flow passage is weak, the compound (C) is likely to flow into the battery container together with the liquid condensed in the gas flow passage.

The polymer compound (P) may contain at least one selected from the group consisting of a hydroxy compound containing a repeating structure of an oxy C _2-4 alkylene unit, an etherified product of the hydroxy compound, and an esterified product of the hydroxy compound. Examples of these compounds will be described later. These polymer compounds (P) are particularly preferred in terms of suppressing the decrease in the electrolyte. By adding these polymer compounds (P) to the negative electrode material, the amount of electricity during overcharging can be particularly reduced.

The polymer compound (P) may be an ester of a polyalkylene glycol having an alkylene group with a carbon number in the range of 2 to 4. The polymer compound (P) may be, for example, at least one selected from the group consisting of an ester of polyethylene glycol and an ester of polypropylene glycol.

The compound (C) may contain a compound (HC) having a hydrophilic group. The compound (HC) having a hydrophilic group may be at least one selected from the group consisting of lignins, condensates containing bisphenol units, naphthalene derivatives, and condensates containing phenolsulfonic acid units. These promote condensation by the hydrophilic group. Examples of hydrophilic groups include hydroxyl groups, carboxy groups, amino groups, sulfo groups, aldehyde groups, nitro groups, and phosphoric acid groups. The compound (HC) may contain at least one hydrophilic group selected from the group consisting of these hydrophilic groups. Examples of lignins, condensates containing bisphenol units, naphthalene derivatives, and condensates containing phenolsulfonic acid units include compounds (described below) contained in the negative electrode material.

Examples of the compound (HC) include some of the examples of organic shrinkage inhibitors described later. For example, examples of lignins include lignin and lignin compounds used as organic shrinkage inhibitors. Examples of condensates containing bisphenol units include condensates containing aromatic compound units described later, which use bisphenol compounds as aromatic compounds. Examples of naphthalene derivatives include organic shrinkage inhibitors having a naphthalene ring. Examples of condensates containing phenolsulfonic acid units include condensates containing at least one type selected from the group consisting of monocyclic aromatic compound (hydroxyarene compound) units described later, which use phenolsulfonic acid as a hydroxyarene compound.

The lid may include a first lid and a second lid. In one example of such a case, at least a part of the second lid is disposed outside the first lid, a part of the first lid constitutes at least a part of the gas flow path, and the reflux structure includes a through hole formed in the first lid so that the condensed liquid is sent into the battery container. Lids having such a structure are publicly known, so a publicly known lid may be used. Typically, the second lid constitutes a part of the gas flow path, and the first lid constitutes the other part of the gas flow path. In such a case, the compound (C) is disposed on the surface of the gas flow path of the second lid and/or on the surface of the gas flow path of the first lid.

The entire second lid may be disposed outside the first lid. Here, outside means the side opposite the center of the lead-acid battery. The second lid may be referred to as the top lid, and the first lid may be referred to as the middle lid.

There is no limitation on the method of disposing the compound (C) on the surface of the gas flow path of the lid. For example, the compound (C) or a liquid containing the compound (C) may be applied to the surface of the gas flow path. There is no particular limitation on the liquid component (solvent or dispersion medium) of the liquid containing the compound (C), and it is preferable to select one that evaporates or has little effect on the battery characteristics even if it remains. Examples of such liquids include water, alcohols such as ethanol, and common organic solvents such as chloroform, acetone, toluene, and hexane.

When manufacturing the battery, the opening of the battery case may be covered with a lid having compound (C) disposed on the surface of the gas flow path. Alternatively, when the lid includes a first and second lid, the battery case may be covered with the first lid (inner lid) and then compound (C) may be disposed on the surface of the gas flow path. The second lid may then be placed in a predetermined position.

The lead-acid battery is, for example, a flooded (vented) lead-acid battery.

In this specification, the content of the polymer compound (P) in the negative electrode material is determined for a negative plate removed from a fully charged lead-acid battery.

(Explanation of terms)
(Electrode material)
The negative electrode material and the positive electrode material are usually held by a current collector. The electrode material is the portion of the electrode plate excluding the current collector. A member such as a mat or pasting paper may be attached to the electrode plate. Such a member (also called an attachment member) is used integrally with the electrode plate and is therefore included in the electrode plate. When the electrode plate includes an attachment member (such as a mat or pasting paper), the electrode material is the portion of the electrode plate excluding the current collector and the attachment 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 chemical shift range of 3.2 ppm or more and 3.8 ppm or less in the 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 oxy C _2-4 alkylene unit. In other words, a polymer compound (P) satisfying condition (ii) is also a polymer compound (P) satisfying condition (i). A polymer compound (P) satisfying condition (i) may contain a repeating structure of a monomer unit other than the oxy C _2-4 alkylene unit, and may have a certain degree of molecular weight. The number average molecular weight (Mn) of a polymer compound (P) satisfying the above (i) or (ii) may be, for example, 300 or more.

(oxy _C2-4 alkylene unit)
The oxy C _2-4 alkylene unit is a unit represented by -O-R ¹ -, where R ¹ represents a C _2-4 alkylene group (an alkylene group having 2 to 4 carbon atoms). R ¹ may contain alkylene groups having different numbers of carbon atoms.

(Organic shrink-proofing agent)
The organic shrinkage inhibitor refers to an organic compound among compounds that have the function of suppressing the shrinkage of lead, which is the negative electrode active material, when a lead-acid 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 in determining Mn is polyethylene glycol.

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

(Sulfur content in organic shrink-proofing agent)
The content of sulfur element in the organic shrink-proofing agent being X μmol/g means that the content of sulfur element contained per 1 g of the organic shrink-proofing agent is X μmol.

(fully charged)
The fully charged state of a flooded lead-acid battery is defined by JIS D 5301:2019. More specifically, the fully charged state is defined as a state in which a lead-acid battery is charged in a water tank at 25°C ± 2°C with a current (A) that is 0.2 times the value (unit: Ah) listed as the rated capacity, until the terminal voltage (V) during charging or the electrolyte density converted to a temperature of 20°C shows a constant value with three significant digits three consecutive times.

A fully charged lead-acid battery refers to a lead-acid battery that has already been chemically prepared and has been fully charged. A lead-acid battery can be fully charged immediately after chemical preparation, or after some time has passed since chemical preparation (for example, a lead-acid battery that has been in use (preferably in the early stages of use) after chemical preparation can be fully charged). An early stage battery refers to a battery that has not been in use for very long and has hardly deteriorated at all.

(Top and bottom directions of lead-acid batteries or components of lead-acid batteries)
In this specification, the up-down direction of a lead-acid battery or components of the lead-acid battery (such as plates, battery case, separator, etc.) refers to the up-down direction in the vertical direction of the lead-acid battery when the lead-acid battery is in use. Each of the positive and negative plates has a lug for connecting to an external terminal. In some cases, such as a horizontal valve-regulated lead-acid battery, the lug is provided on the side of the plate so as to protrude laterally, but in most lead-acid batteries, the lug is usually provided on the top of the plate so as to protrude upward.

Below, the lead-acid battery according to an embodiment of the present invention will be described in terms of its main components, but the present invention is not limited to the following embodiment.

[Lead-acid battery]
(Negative plate)
The negative plate includes a negative current collector and a negative electrode material supported on the negative 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 and punching. It is preferable to use a lattice-shaped current collector as the negative electrode current collector because it is easy to support the negative electrode material.

The lead alloy used in the negative electrode current collector may be any of Pb-Sb alloy, Pb-Ca alloy, and Pb-Ca-Sn alloy. These lead or lead alloys may further contain at least one selected from the group consisting of Ba, Ag, Al, Bi, As, Se, Cu, etc. as an additive element. The negative electrode current collector may have 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 ear portion of the negative electrode current collector. The surface layer of the ear portion may contain Sn or an Sn alloy.

(Negative electrode material)
The negative electrode material includes a negative electrode active material (specifically, lead or lead sulfate) that exhibits capacity by an oxidation-reduction reaction. The negative electrode material may include a polymer compound (P). The negative electrode material may include at least one selected from the group consisting of a carbonaceous material and other additives. Examples of additives include, but are not limited to, organic shrinkage inhibitors, barium sulfate, and fibers (such as resin fibers). Note that the negative electrode active material in a charged state is sponge-like lead, but an unformed negative plate is usually made using lead powder.

(Polymer Compound (P))
The polymer compound (P) will be described below. The polymer compound (P) described below may be disposed on at least a part of the surface of the gas flow passage portion, or may be contained in the negative electrode material. A first example of the polymer compound (P) has a peak in the range of 3.2 ppm to 3.8 ppm in the chemical shift of the ¹ H-NMR spectrum. Such a polymer compound (P) has an oxy C _2-4 alkylene unit. Examples of the oxy C _2-4 alkylene unit contained in the polymer compound (P) include an oxyethylene unit, an oxypropylene unit, an oxytrimethylene unit, an oxy 2-methyl-1,3-propylene unit, an oxy 1,4-butylene unit, and an oxy 1,3-butylene unit. The polymer compound (P) may have one type of such oxy C _2-4 alkylene unit, or may have two or more types.

The polymer compound (P) preferably contains a repeating structure of an oxy _C2-4 alkylene unit. The repeating structure may contain one type of oxy _C2-4 alkylene unit, or may contain two or more types of oxy _C2-4 alkylene units. The polymer compound (P) may contain one type of the above repeating structure, or may contain two or more types of the above repeating structures.

The polymer compound (P) having a repeating structure of oxy-C _2-4 alkylene units also includes those classified as surfactants (more specifically, nonionic surfactants).

Examples of the polymer compound (P) include hydroxy compounds having a repeating structure of oxy _C2-4 alkylene units (poly _C2-4 alkylene glycol, copolymers containing a repeating structure of oxy _C2-4 alkylene, poly _C2-4 alkylene oxide adducts of polyols, etc.), ethers or esters of these hydroxy compounds, etc. Examples of poly _C2-4 alkylene glycols include polyethylene glycol, polypropylene glycol, and polyoxyethylene polyoxypropylene glycol.

Copolymers include those containing different oxyC _2-4 alkylene units. The copolymer may be a block copolymer.

In the polymer compound (P) containing a repeating structure of oxy C _2-4 alkylene units, the proportion of the oxy C _2-4 alkylene units in all constitutional units may be in the range of 50 mol% to 100 mol%, or in the range of 60 mol% to 100 mol% (for example, in the range of 75 mol% to 100 mol%), or in the range of 60 mol% to 95 mol% (for example, in the range of 75 mol% to 95 mol%). Here, the oxy C _2-4 alkylene units may be oxyethylene units and/or oxypropylene units.

The polyol may be any of aliphatic polyols, alicyclic polyols, aromatic polyols, and heterocyclic polyols. From the viewpoint that the polymer compound (P) is likely to spread thinly on the lead surface, aliphatic polyols and alicyclic polyols (e.g., polyhydroxycyclohexane, polyhydroxynorbornane, etc.) are preferred, and among them, aliphatic polyols are preferred. Examples of aliphatic polyols include aliphatic diols and polyols having a triol or more (e.g., glycerin, trimethylolpropane, pentaerythritol, sugar or sugar alcohol, etc.). Examples of aliphatic diols include alkylene glycols having 5 or more carbon atoms. Examples of alkylene glycols may be C _5-14 alkylene glycols or C _5-10 alkylene glycols. Examples of sugars or sugar alcohols include sucrose, erythritol, xylitol, mannitol, sorbitol, etc. The sugars or sugar alcohols may have either a chain structure or a cyclic structure. In the polyalkylene oxide adduct of polyol, the alkylene oxide corresponds to the oxy _C2-4 alkylene unit of the polymer compound (P) and contains at least a _C2-4 alkylene oxide. From the viewpoint that the polymer compound (P) is likely to have a linear structure, the polyol is preferably a diol.

The etherified product has an _-OR2 group (wherein R2 is an organic group) in which at least some of the terminal -OH groups (-OH groups consisting of a hydrogen atom of the terminal group and an oxygen atom bonded to this hydrogen atom) of the hydroxy compound having a repeating structure of the above-mentioned oxy ^{C2-4 alkylene} unit are etherified. Of the terminals of the polymer compound (P), ^some terminals may be etherified, or all terminals may be etherified. For example, one terminal of the main chain of the linear polymer compound (P) may be an -OH group, and the other terminal may be an ^-OR2 group.

The esterified product has an -O-C(=O ₎ -R3 group in which at least some of the terminal ^-OH groups (-OH groups consisting of a hydrogen atom of the terminal group and an oxygen atom bonded to this hydrogen atom) of the hydroxy compound having a repeating structure of the above oxy C2-4 alkylene unit are esterified (wherein ^R3 is an organic group). Of the terminals of the polymer compound (P), some terminals may be esterified, or all terminals may be esterified. For example, one terminal of the main chain of the linear polymer compound (P) may be an -OH group, and the other terminal may be an -O-C(=O) ^-R3 group.

Each of the organic groups ^R2 and ^R3 includes a hydrocarbon group. The hydrocarbon group may have a substituent (e.g., a hydroxy group, an alkoxy group, and/or a carboxy group). The hydrocarbon group may be any of aliphatic, alicyclic, and aromatic. The aromatic hydrocarbon group and the alicyclic hydrocarbon group may have an aliphatic hydrocarbon group (e.g., 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, 1 to 6, or 1 to 4.

Examples of aromatic hydrocarbon groups include aromatic hydrocarbon groups having 24 or less carbon atoms (e.g., 6 to 24). The number of carbon atoms in the aromatic hydrocarbon group may be 20 or less (e.g., 6 to 20), 14 or less (e.g., 6 to 14), or 12 or less (e.g., 6 to 12). Examples of aromatic hydrocarbon groups include aryl groups and bisaryl groups. Examples of aryl groups include phenyl groups and naphthyl groups. Examples of bisaryl groups include monovalent groups corresponding to bisarenes. Examples of bisarenes include biphenyl and bisarylalkanes (e.g., bisC _6-10 aryl C _1-4 alkanes (2,2-bisphenylpropane, etc.)).

Examples of alicyclic hydrocarbon groups include alicyclic hydrocarbon groups having 16 or less carbon atoms. The alicyclic hydrocarbon group may be a cross-linked cyclic hydrocarbon group. The number of carbon atoms in the alicyclic hydrocarbon group may be 10 or less or 8 or less. The number of carbon atoms in the alicyclic hydrocarbon group may be, for example, 5 or more, or 6 or more.

The number of carbon atoms in 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 alicyclic hydrocarbon groups include cycloalkyl groups (cyclopentyl, cyclohexyl, cyclooctyl, etc.) and cycloalkenyl groups (cyclohexenyl, cyclooctenyl, etc.). Alicyclic hydrocarbon groups also include hydrogenated products of the above aromatic hydrocarbon groups.

Among the hydrocarbon groups, aliphatic hydrocarbon groups are preferred. The aliphatic hydrocarbon group 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 either linear or branched.

The number of carbon atoms in the aliphatic hydrocarbon group is, for example, 30 or less, and may be 26 or less or 22 or less, 20 or less or 16 or less, 14 or less or 10 or less, or 8 or less or 6 or less. The lower limit of the number of carbon atoms depends on the type of aliphatic hydrocarbon group, and is 1 or more for alkyl groups, 2 or more for alkenyl groups and alkynyl groups, 3 or more for dienyl groups, and 4 or more for trienyl groups. Among these, alkyl and alkenyl groups are preferred.

Specific examples of alkyl groups include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl, neopentyl, i-pentyl, 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, icosyl, henicosyl, and behenyl.

Specific examples of alkenyl groups include vinyl, 1-propenyl, allyl, cis-9-heptadecen-1-yl, palmitoleyl, oleyl, etc. 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, or a C _10-20 alkenyl group.

Of the polymer compounds (P), at least one selected from the group consisting of etherified products of hydroxy compounds having a repeating structure of oxy C _2-4 alkylene units and esterified products of hydroxy compounds having a repeating structure of oxy C _2-4 alkylene units may be used. By adding these to the negative electrode material, it is possible to particularly suppress the decrease in charge acceptance and particularly reduce the amount of overcharge electricity. The repeating structure of the oxy C _2-4 alkylene units may be a repeating structure of an oxypropylene unit and/or a repeating structure of an oxyethylene unit.

The polymer compound (P) may be a polymer compound having one or more hydrophobic groups. Examples of the hydrophobic group include, among the above-mentioned hydrocarbon groups, aromatic hydrocarbon groups, alicyclic hydrocarbon groups, and long-chain aliphatic hydrocarbon groups. Examples of the long-chain aliphatic hydrocarbon group include, among the above-mentioned aliphatic hydrocarbon groups (alkyl groups, alkenyl groups, etc.), groups having 8 or more carbon atoms, preferably 12 or more, and more preferably 16 or more. The polymer compound (P) may be one in which at least one of the hydrophobic groups is 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 in the long chain aliphatic hydrocarbon group may be 8 or more (or 12 or more) and 30 or less, 8 or more (or 12 or more) and 26 or less, 8 or more (or 12 or more) and 22 or less, 10 or more and 30 or less (or 26 or less), or 10 or more and 22 or less.

Examples of the polymer compound (P) having a hydrophobic group and containing a repeating structure of oxyethylene units include etherified products of polyethylene glycol (such as alkyl ethers), esterified products of polyethylene glycol (such as carboxylic acid esters), etherified products of polyethylene oxide adducts of the above polyols (such as alkyl ethers), and esterified products of polyethylene oxide adducts of the above polyols (such as triols or higher polyols) (such as carboxylic acid esters). Specific examples of such polymer compounds (P) include polyethylene glycol oleate, polyethylene glycol dioleate, polyethylene glycol dilaurate, polyethylene glycol distearate, polyoxyethylene coconut oil fatty acid sorbitan, polyoxyethylene sorbitan oleate, polyoxyethylene sorbitan stearate, polyoxyethylene lauryl ether, polyoxyethylene tetradecyl ether, and polyoxyethylene cetyl ether, but the polymer compound (P) is not limited to these. Among these, esterified products of polyethylene glycol and esterified products of polyethylene oxide adducts of the above polyols are preferably used.

It is also preferred that the repeating structure of oxyC _2-4 alkylene contains at least a repeating structure of an oxypropylene unit. A polymer compound (P) containing an oxypropylene unit has peaks derived from -CH< and -CH ₂ - of the oxypropylene unit in the chemical shift range of 3.2 ppm to 3.8 ppm in the ¹ H-NMR spectrum. The peaks are split because the electron densities around the nuclei of the hydrogen atoms in these groups are different. Such a polymer compound (P) has peaks in the chemical shift range of ¹ H-NMR spectrum, for example, in the range of 3.2 ppm to 3.42 ppm and in the range of more than 3.42 ppm to 3.8 ppm. The peaks in the range of 3.2 ppm to 3.42 ppm are derived from -CH ₂ -, and the peaks in the range of more than 3.42 ppm to 3.8 ppm are derived from -CH< and -CH ₂ -.

Examples of the polymer compound (P) containing at least a repeating structure of an oxypropylene unit include polypropylene glycol, a copolymer containing a repeating structure of an oxypropylene unit, a polypropylene oxide adduct of the above polyol, or an etherified or esterified product thereof. Examples of the copolymer include an oxypropylene-oxyalkylene copolymer (wherein the oxyalkylene is a _C2-4 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 (e.g., a polyoxypropylene-polyoxyethylene copolymer). The oxypropylene-oxyalkylene copolymer may be a block copolymer (e.g., a polyoxypropylene-polyoxyethylene block copolymer). Examples of the etherified products include polypropylene glycol alkyl ethers, alkyl ethers of oxypropylene-oxyalkylene copolymers (such as alkyl ethers of polyoxypropylene-polyoxyethylene copolymers), etc. Examples of the esterified products include polypropylene glycol esters of carboxylic acids, carboxylic acid esters of oxypropylene-oxyalkylene copolymers (such as carboxylic acid esters of polyoxypropylene-polyoxyethylene copolymers), etc.

Examples of the polymer compound (P) containing at least a repeating structure of oxypropylene units include polypropylene glycol, polyoxypropylene-polyoxyethylene copolymers (polyoxypropylene-polyoxyethylene block copolymers, etc.), polyoxyethylene-polyoxypropylene alkyl ethers (alkyl ethers (butyl ethers, etc.) in which the above R ² is an alkyl having 10 or less carbon atoms (or 8 or less or 6 or less), polypropylene glycol carboxylates (polypropylene glycol acetates, etc.) in which the above R ³ is an alkyl having 10 or less carbon atoms (or 8 or less or 6 or less), and polypropylene oxide adducts of triol or higher polyols (polypropylene oxide adducts of glycerin, etc.), but the polymer compound (P) is not limited to these.

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

In the polymer compound (P) containing a repeating structure of oxypropylene units, the proportion of oxypropylene units may be 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% or more and 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), or 20 mol% or more and 75 mol% or less (or 60 mol% or less).

The polymer compound (P) preferably contains a large amount of oxy C _2-4 alkylene units. Such a polymer compound (P) contains, for example, an oxygen atom bonded to an end group, and a -CH ₂ - group and/or a -CH< group bonded to the oxygen atom. In the ¹ H-NMR spectrum of the polymer compound (P), the integral value V ₁ of the peak at 3.2 ppm to 3.8 ppm accounts for a large proportion of the sum V _SUM of the integral values of the specified peaks. Here, the sum V _SUM of the integral values of the peaks is the sum of the integral value V ₁ , the integral value of the peak of the hydrogen atom of the -CH ₂ - group, and the integral value of the peak of the hydrogen atom of the -CH< group. This proportion is, for example, 50% or more, and may be 80% or more. The above proportion is preferably 85% or more, and more preferably 90% or more. For example, when the polymer compound (P) has an -OH group at its terminal and a -CH ₂ - group or a -CH< group bonded to the oxygen atom of the -OH group, the peak of the hydrogen atom of the -CH ₂ - group or the -CH< group has a chemical shift in the range of more than 3.8 ppm to 4.0 ppm in the ¹ H-NMR spectrum.

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

The polymer compound (P) may, for example, include a compound with an Mn of 5 million or less, a compound with an Mn of 3 million or less or 2 million or less, a compound with an Mn of 500,000 or less or 100,000 or less, or a compound with an Mn of 50,000 or less or 20,000 or less. The polymer compound (P) preferably includes a compound with an Mn of 10,000 or less, a compound with an Mn of 5,000 or less or 4,000 or less, or a compound with an Mn of 3,000 or less or 2,500 or less. The Mn of such a compound may be 300 or more or 400 or more, or may be 500 or more. From the viewpoint of further enhancing the effect of reducing the overcharge quantity of electricity, the Mn of such a compound is preferably 1,000 or more, more preferably 1,500 or more or 1,800 or more. As the polymer compound (P), two or more compounds with different Mn may be used. In other words, the polymer compound (P) may be a polymer compound having multiple Mn peaks in the molecular weight distribution.

Mn of the polymer compound (P) is 300 or more (or 400 or more) and 5 million or less, 300 or more (or 400 or more) and 3 million or less, 300 or more (or 400 or more) and 2 million or less, 300 or more (or 400 or more) and 500,000 or less, 300 or more (or 400 or more) and 100,000 or less, 300 or more (or 400 or more) and 50,000 or less, 300 or more (or 400 or more) and 20,000 or less, 300 or more (or 400 or more) and 10,000 or less, 300 or more (or 400 or more) and 5,000 or less, 300 or more (or 400 or more) and 4,000 or less, 300 or more (or 400 or more) and 3,000 or less, 300 or more (or 400 or more) and 2,500 or less, 500 or more (or 1,000 or more) and 5 million or less, 500 or more (or 1,000 or more) and 3 million or less, 500 or more (or 1,000 or more) and 2 million or less, 500 or more (or 1,000 or more) and 500,000 or less, 500 or more (or 1,000 or more) and 100,000 or less, 500 or more (or 1,000 or more) and 5 ... 0 or more) 20,000 or less, 500 or more (or 1,000 or more) 10,000 or less, 500 or more (or 1,000 or more) 5,000 or less, 500 or more (or 1,000 or more) 4,000 or less, 500 or more (or 1,000 or more) 3,000 or less, 500 or more (or 1,000 or more) 2,500 or less, 1,500 or more (or 1,800 or more) 5 million or less, 1,500 or more (or 1,800 or more) 3 million or less, 1,500 or more (or 1,800 or more) 2 million or less, 1,500 or more (or 1,800 or more) or more) but not exceeding 500,000, 1500 or more (or 1800 or more) but not exceeding 100,000, 1500 or more (or 1800 or more) but not exceeding 50,000, 1500 or more (or 1800 or more) but not exceeding 20,000, 1500 or more (or 1800 or more) but not exceeding 10,000, 1500 or more (or 1800 or more) but not exceeding 5,000, 1500 or more (or 1800 or more) but not exceeding 4,000, 1500 or more (or 1800 or more) but not exceeding 3,000, or 1500 or more (or 1800 or more) but not exceeding 2,500.

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

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

(Organic shrink-proofing agent)
Organic shrink-proofing agents are generally classified into lignin compounds and synthetic organic shrink-proofing agents. Synthetic organic shrink-proofing agents can also be said to be organic shrink-proofing agents other than lignin compounds. Examples of organic shrink-proofing agents contained in the negative electrode material include lignin compounds and synthetic organic shrink-proofing agents. The negative electrode material may contain one type of organic shrink-proofing agent or two or more types of organic shrink-proofing agents.

Examples of lignin compounds include lignin and lignin derivatives. Examples of lignin derivatives include lignin sulfonic acid or its salts (alkali metal salts (sodium salts, etc.)).

Synthetic organic shrinkage inhibitors are organic polymers containing elemental sulfur, and generally contain multiple aromatic rings in the molecule, as well as elemental sulfur as a sulfur-containing group. Among the sulfur-containing groups, sulfonic acid groups or sulfonyl groups, which are stable, are preferred. The sulfonic acid groups may exist in the acid form or in the salt form, such as the Na salt.

At least a lignin compound may be used as the organic shrinkage inhibitor.

As the organic shrink-proofing agent, it is also preferable to use a condensation product containing at least an aromatic compound unit. For example, such a condensation product may be a condensation product of an aromatic compound with an aldehyde compound (at least one selected from the group consisting of aldehydes (e.g., formaldehyde) and condensates thereof). The organic shrink-proofing agent may contain one type of aromatic compound unit, or may contain two or more types of aromatic compound units.
The aromatic compound unit refers to a unit derived from an aromatic compound incorporated in the condensation product.

Examples of aromatic rings that aromatic compounds have include benzene rings and naphthalene rings. When aromatic compounds have multiple aromatic rings, the multiple aromatic rings may be linked by direct bonds or linking groups (e.g., alkylene groups (including alkylidene groups), sulfone groups). Examples of such structures include bisarene structures (biphenyl, bisphenylalkane, bisphenylsulfone, etc.). Examples of aromatic compounds include compounds having the above aromatic rings and at least one selected from the group consisting of hydroxyl groups and amino groups. The hydroxyl group or amino group may be directly bonded to the aromatic ring, or may be bonded as an alkyl chain having a hydroxyl group or amino group. The hydroxyl group also includes salts of the hydroxyl group (-OMe). The amino group also includes salts of the amino group (specifically, salts with anions). Examples of Me include alkali metals (Li, K, Na, etc.) and metals of Group 2 of the Periodic Table (Ca, Mg, etc.).

As the aromatic compound, bisarene compounds [bisphenol compounds, hydroxybiphenyl compounds, bisarene compounds having an amino group (bisarylalkane compounds having an amino group, bisarylsulfone compounds having an amino group, biphenyl compounds having an amino group, etc.), hydroxyarene compounds (hydroxynaphthalene compounds, phenol compounds, etc.), aminoarene compounds (aminonaphthalene compounds, aniline compounds (aminobenzenesulfonic acid, alkylaminobenzenesulfonic acid, etc.), etc.)] are preferred. The aromatic compound may further have a substituent. The organic shrinkage inhibitor may contain one or more of the residues of these compounds. As the bisphenol compound, bisphenol A, bisphenol S, bisphenol F, etc. are preferred.

The condensate preferably contains at least a unit of an aromatic compound having a sulfur-containing group. In particular, the use of a condensate containing at least a unit of a bisphenol compound having a sulfur-containing group is advantageous in terms of ensuring higher charge acceptance. From the viewpoint of increasing the effect of reducing the amount of overcharge electricity, it is also preferable to use a condensate of an aldehyde compound with a naphthalene compound having a sulfur-containing group and at least one group selected from the group consisting of a hydroxyl group and an amino group.

The sulfur-containing group may be directly bonded to an aromatic ring contained in the compound, or may be bonded to the aromatic ring as an alkyl chain having a sulfur-containing group. The sulfur-containing group is not particularly limited, but examples thereof include a sulfonyl group, a sulfonic acid group, or a salt thereof.

As the organic shrinkage inhibitor, for example, at least one condensate containing at least one selected from the group consisting of the above-mentioned bisarene compound units and monocyclic aromatic compound units (hydroxyarene compounds and/or aminoarene compounds, etc.) may be used. The organic shrinkage inhibitor may contain at least a condensate containing a bisarene compound unit and a monocyclic aromatic compound (particularly, a hydroxyarene compound). Such a condensate may be a condensate of a bisarene compound and a monocyclic aromatic compound with an aldehyde compound. As the hydroxyarene compound, a phenolsulfonic acid compound (phenolsulfonic acid or a substituted compound thereof, etc.) is preferable. That is, the organic condensate may be a condensate containing a phenolsulfonic acid unit. As the aminoarene compound, aminobenzenesulfonic acid, alkylaminobenzenesulfonic acid, etc. are preferable. As the monocyclic aromatic compound, a hydroxyarene compound is preferable.

The content of the organic shrinkage inhibitor contained in the negative 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 inhibitor is in such a range, a high low-temperature high-rate discharge capacity can be ensured. The content of the organic shrinkage inhibitor 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 acceptance, the content of the organic shrinkage inhibitor is preferably 0.3% by mass or less, more preferably 0.25% by mass or less, further preferably 0.2% by mass or less or 0.15% by mass or less, and may be 0.12% by mass or less. These lower and upper limits can be arbitrarily combined as long as there is no contradiction.

The content of the organic shrinkage inhibitor contained in the negative electrode material may be 0.005% by mass or more (or 0.01% by mass or more) to 1.0% by mass or less, 0.005% by mass or more (or 0.01% by mass or more) to 0.5% by mass or less, 0.005% by mass or more (or 0.01% by mass or more) to 0.3% by mass or less, 0.005% by mass or more (or 0.01% by mass or more) to 0.25% by mass or less, 0.005% by mass or more (or 0.01% by mass or more) to 0.2% by mass or less, 0.005% by mass or more (or 0.01% by mass or more) to 0.15% by mass or less, or 0.005% by mass or more (or 0.01% by mass or more) to 0.12% by mass or less.

(Carbonaceous materials)
Carbon black, graphite, hard carbon, soft carbon, etc. can be used as the carbonaceous material contained in the negative electrode material. Examples of carbon black include acetylene black, furnace black, lamp black, etc. Furnace black also includes Ketjen Black (trade name). 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 type of carbonaceous material, or may contain two or more types.

The content of the carbonaceous material in the negative 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 may be 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% by mass or more and 3% by mass or less.

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

The barium sulfate content in the negative electrode material may be 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 or more and 2% by mass or less.

(Analysis of compounds placed in the gas flow passage)
The compound placed in the gas flow passage is extracted by washing the cover including the gas flow passage with water to remove sulfuric acid, and then drying the cover. The dried cover is immersed in a chloroform solution or a sodium hydroxide solution to extract the compound. Then, qualitative and quantitative analysis are performed according to the analysis method for the compound in the negative electrode material.

(Analysis of negative electrode materials or components)
The following describes a method for analyzing the negative electrode material or its constituents. 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. The washing is performed by pressing a pH test paper against the washed surface of the negative electrode plate until it is confirmed that the color of the test paper does not change. However, the washing time is within 2 hours. The washed negative electrode plate is dried at 60±5° C. for about 6 hours under a reduced pressure environment. If the negative electrode plate contains an attachment member, the attachment 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 crushed as necessary and subjected to analysis.

(1) Analysis of polymer compound (P) (1-1) Qualitative analysis of polymer compound (P) When analyzing the polymer compound (P) in the negative electrode material, a crushed 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. The polymer compound (P) is identified by obtaining information from at least one of infrared spectroscopy, ultraviolet-visible absorption spectrum, NMR spectrum, LC-MS, and pyrolysis GC-MS for 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.

From the chloroform solution in which the polymer compound (P) obtained by extraction is dissolved, chloroform is distilled off under reduced pressure to recover a chloroform-soluble fraction. The chloroform-soluble fraction is dissolved in deuterated chloroform, and a ¹ H-NMR spectrum is measured under the following conditions. From this ¹ H-NMR spectrum, a peak in the chemical shift range of 3.2 ppm to 3.8 ppm is confirmed. Furthermore, from the peak in this range, the type of oxy C _2-4 alkylene unit is identified.

Apparatus: AL400 type nuclear magnetic resonance apparatus manufactured by JEOL Ltd. Observation frequency: 395.88 MHz
Pulse width: 6.30 μs
Pulse repetition time: 74.1411 seconds Number of integrations: 32
Measurement temperature: room temperature (20-35℃)
Standard: 7.24 ppm
Sample tube diameter: 5 mm

From the ¹ H-NMR spectrum, the integral value (V ₁ ) of the peaks present in the chemical shift range of 3.2 ppm or more and 3.8 ppm or less is obtained. In addition, the sum (V 2 ) of the integral values of the peaks in the ¹ H-NMR spectrum is obtained for each of the hydrogen atoms of the -CH ₂ - groups and -CH< groups bonded to the oxygen atoms bonded to the end groups of the polymer compound ( _P ). Then, from V ₁ and V ₂ , the proportion of V ₁ to the sum of V ₁ and V ₂ (= V ₁ / (V ₁ + V ₂ ) × 100 (%)) is obtained.

In addition, when determining the integral value of a peak in a ¹ H-NMR spectrum in a qualitative analysis, two points on the ¹ H-NMR spectrum that have no significant signals are determined so as to sandwich the relevant peak, and each integral value is calculated using a straight line connecting these two points as a baseline. For example, for a peak that exists in a chemical shift range of 3.2 ppm to 3.8 ppm, a straight line connecting two points on the spectrum, 3.2 ppm and 3.8 ppm, is used as the baseline. For example, for a peak that exists in a chemical shift range of more than 3.8 ppm to 4.0 ppm, a straight line connecting two points on the spectrum, 3.8 ppm and 4.0 ppm, is used as the baseline.

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

C _n =S _a /S _r ×N _r /N _a ×M _a /M _r ×m _r /m × 1000000
(In the formula, M _a is the molecular weight of a structure that exhibits a peak in the chemical shift range of 3.2 to 3.8 ppm (more specifically, the molecular weight of a repeating structure of an oxyC _2-4 alkylene unit), and N _a is the number of hydrogen atoms bonded to the carbon atoms of the main chain of the repeating structure. _{Nr and Mr} are the number of hydrogen atoms contained in the molecule of the reference substance and the molecular weight of the reference substance, respectively, and m (g) is the extraction is the mass of the negative electrode material used.)
In addition, since the reference substance in this analysis is TCE, N _r =2, M _r =168, and m=100.

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

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

(1-3) Measurement of Mn of polymer compound (P) Using the above chloroform solubles, GPC measurement of polymer compound (P) is performed using the following apparatus under the following conditions. A calibration curve (calibration curve) is separately created from a plot of Mn and elution time of a standard substance. Based on this calibration curve and the GPC measurement results of polymer compound (P), Mn of polymer compound (P) is calculated. However, esterified products or etherified products may be in a decomposed state in the chloroform solubles.

Analysis system: 20A system (manufactured by Shimadzu Corporation)
Column: GPC KF-805L (Shodex), two columns 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 refractive index detector (Shodex RI-201H)

(2) Analysis of organic shrink-preventing agent (2-1) Qualitative analysis of organic shrink-preventing agent in negative electrode material When analyzing an organic shrink-preventing agent in a negative electrode material, a pulverized sample A is used. The pulverized sample A is immersed in a 1 mol/L aqueous sodium hydroxide solution to extract the organic shrink-preventing agent. Next, the first organic shrink-preventing agent and the second organic shrink-preventing agent are separated from the extract as necessary. For each of the separated products containing each organic shrink-preventing agent, insoluble components are removed by filtration, and the resulting solution is desalted, concentrated, and dried. Desalting is performed using a desalting column, or by passing the solution through an ion exchange membrane, or by putting the solution into a dialysis tube and immersing it in distilled water. This is dried to obtain a powder sample of the organic shrink-preventing agent (hereinafter referred to as sample B).

The type of organic shrinkage inhibitor is identified by combining information obtained from the infrared spectrum measured using sample B of the organic shrinkage inhibitor obtained in this manner, the ultraviolet-visible absorption spectrum measured using an ultraviolet-visible spectrometer after diluting sample B with distilled water or the like, the NMR spectrum of the solution obtained by dissolving sample B in a specified solvent such as heavy water, or information obtained from pyrolysis GC-MS, which can provide information on the individual compounds that make up the substance.

(2-2) Determination of the content of organic shrinkage inhibitor in the negative electrode material As in (2-1) above, for each of the separated products containing the organic shrinkage inhibitor, a solution is obtained after removing insoluble components by filtration. For each of the obtained solutions, the ultraviolet-visible absorption spectrum is measured. The content of each organic shrinkage inhibitor in the negative electrode material is determined using the intensity of the peak characteristic of each organic shrinkage inhibitor and a calibration curve prepared in advance.

When obtaining a lead-acid battery with an unknown content of organic shrink inhibitor and measuring the content of the organic shrink inhibitor, it may not be possible to use the same organic shrink inhibitor for the calibration curve because the structural formula of the organic shrink inhibitor cannot be precisely identified. In this case, a calibration curve is created using the organic shrink inhibitor extracted from the negative electrode of the battery and a separately available organic polymer whose ultraviolet-visible absorption spectrum, infrared spectroscopy spectrum, and NMR spectrum show similar shapes, and the content of the organic shrink inhibitor is measured using the ultraviolet-visible absorption spectrum.

(3) Quantitative Determination of Carbonaceous Material and Barium Sulfate 50 ml of 20% by mass nitric acid was added to 10 g of the pulverized sample A, and the mixture was heated for about 20 minutes to dissolve the lead component as lead nitrate. Next, the solution containing lead nitrate was filtered to separate the carbonaceous material, barium sulfate, and other solids.

The obtained solid content is dispersed in water to obtain a dispersion liquid, and then a sieve is used to remove components other than the carbonaceous material and barium sulfate (e.g., reinforcing material) from the dispersion liquid. Next, the dispersion liquid is subjected to suction filtration using a membrane filter whose mass has been measured in advance, and the membrane filter together with the filtered sample is dried in a dryer at 110°C ± 5°C. The filtered sample is a mixed sample of the carbonaceous material and barium sulfate. The mass of the membrane filter is subtracted from the total mass of the mixed sample after drying (hereinafter referred to as sample C) and the membrane filter to measure the mass (M _m ) of sample C. Then, sample C is placed in a crucible together with the membrane filter and incinerated at 700°C or higher. The remaining residue is barium oxide. The mass of barium oxide is converted to the mass of barium sulfate to obtain the mass (M _B ) of barium sulfate. The mass of the carbonaceous material is calculated by subtracting the mass M _B from the mass M _m .

(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 prepare an unformed negative electrode plate, and then chemically forming the unformed negative electrode plate. The negative electrode paste is prepared, for example, by adding water and sulfuric acid (or an aqueous sulfuric acid solution) to lead powder, a polymer compound (P), and, if necessary, at least one selected from the group consisting of an organic shrinkage inhibitor, a carbonaceous material, and other additives, and kneading them. When aging, it is preferable to age the unformed negative electrode plate at a temperature higher than room temperature and at a high humidity.

The chemical formation can be carried out by immersing the plate group, including the unformed negative plate, in an electrolyte containing sulfuric acid in a lead-acid battery container and then charging the plate group. However, chemical formation can also be carried out before assembling the lead-acid battery or the plate group. Chemical formation produces spongy lead.

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

As the lead alloy used for the positive electrode collector, in terms of corrosion resistance and mechanical strength, a Pb-Sb alloy, a Pb-Ca alloy, or a Pb-Ca-Sn alloy is preferable. The positive electrode collector may have a surface layer. The surface layer and the inner layer of the positive electrode collector may have different compositions. The surface layer may be formed on a part of the positive electrode collector. The surface layer may be formed only on the lattice part, the edge part, or the frame part of the positive electrode collector.

The positive electrode material contained in the positive plate contains a positive electrode active material (lead dioxide or lead sulfate) that develops capacity through an oxidation-reduction reaction. The positive electrode material may contain other additives as necessary.

An unformed paste-type positive plate is obtained by filling a positive current collector with a positive electrode paste, aging it, and drying it. The positive electrode paste is prepared by kneading lead powder, additives, water, and sulfuric acid. An unformed clad-type positive plate is formed by filling a porous tube into which a core metal connected by a current collector is inserted with lead powder or lead powder in a slurry form, and connecting multiple tubes with a connecting member. Then, these unformed positive plates are formed to obtain a positive plate. Formation can be performed by charging the plate group, with the plate group including the unformed positive plate immersed in an electrolyte containing sulfuric acid in a lead-acid battery container. However, formation may be performed before assembling the lead-acid battery or the plate group.

The chemical formation can be carried out by immersing the plate group including the unformed positive plate in an electrolyte containing sulfuric acid in a lead-acid battery container and then charging the plate group. However, chemical formation may also be carried out before assembling the lead-acid battery or the plate group.

(Separator)
A separator may be disposed between the negative electrode plate and the positive electrode plate, and may be made of at least one material selected from a nonwoven fabric and a microporous membrane.

A nonwoven fabric is a mat of intertwined fibers, not woven, and is mainly composed of fibers. For example, 60% or more by mass of the nonwoven fabric is made of fibers. Examples of fibers that can be used include glass fibers, polymer fibers (polyolefin fibers, acrylic fibers, polyester fibers (polyethylene terephthalate fibers, etc.)), and pulp fibers. Among these, glass fibers are preferred. The nonwoven fabric may contain components other than fibers, such as acid-resistant inorganic powders and polymers as binders.

On the other hand, a microporous membrane is a porous sheet mainly composed of components other than fiber components, and can be obtained, for example, by extruding a composition containing a pore-forming agent into a sheet, and then removing the pore-forming agent to form pores. The microporous membrane is preferably made of an acid-resistant material, and preferably is mainly composed of a polymer component. The polymer component is preferably polyolefin (polyethylene, polypropylene, etc.). The pore-forming agent can be at least one selected from the group consisting of polymer powder and oil.

The separator may be made of, for example, only nonwoven fabric or only microporous membrane. If necessary, the separator may be a laminate of nonwoven fabric and microporous membrane, a laminate of different or the same materials, or a laminate of different or the same materials with interlocking recesses and projections.

The separator may be in the form of a sheet or a bag. A sheet-like separator may be sandwiched between the positive and negative plates. Alternatively, the electrode plates may be sandwiched between a folded sheet-like separator. In this case, the positive plate sandwiched between the folded sheet-like separator and the negative plate sandwiched between the folded sheet-like separator may be stacked, or one of the positive and negative plates may be sandwiched between the folded sheet-like separator and stacked with the other electrode plate. Alternatively, the sheet-like separator may be folded into an accordion shape, and the positive and negative plates may be sandwiched between the accordion-like separator so that the separator is interposed between them. When a bag-like separator is used, the bag-like separator may house the positive or negative plate.

(Electrolyte)
The electrolyte is an aqueous solution containing sulfuric acid, which may be gelled as necessary. The electrolyte may contain the above-mentioned polymer compound (P).

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

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

The specific gravity of the electrolyte 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 housing a plate group and an electrolyte in a cell chamber of a battery case. Each cell of the lead-acid battery includes a plate group and an electrolyte housed in each cell chamber. The plate group is assembled by stacking a positive electrode plate, a negative electrode plate, and a separator such that the separator is interposed between the positive electrode plate and the negative electrode plate prior to housing in the cell chamber. The positive electrode plate, the negative electrode plate, the electrolyte, and the separator are each prepared prior to assembling the plate group. The manufacturing method of the lead-acid battery may include a step of chemically forming at least one of the positive electrode plate and the negative electrode plate, as necessary, after the step of housing the plate group and the electrolyte in the cell chamber. Each plate in the plate group may be one sheet, or two or more sheets.

An example of a lead-acid battery according to one embodiment of the present invention will be described below with reference to the drawings. The above description can be applied to the embodiment described below. The embodiment described below may be modified based on the above description. The matters described below may be applied to the above embodiment. Among the matters described below, matters that are not essential to the present invention may be omitted. In the drawings below, some symbols may be omitted to facilitate understanding.

Figure 1 shows the external appearance of an example of a lead-acid battery according to one embodiment of the present invention. Lead-acid battery 1 includes an electrolyte (not shown), a plate group 11, and an exterior body 10. Exterior body 10 includes a battery case 12 that contains the electrolyte and plate group 11, and a lid portion 20 that is disposed at the opening of battery case 12.

The inside of the battery case 12 is divided into multiple cell chambers 14 by partitions 13. Each cell chamber 14 contains one electrode plate group 11. The opening of the battery case 12 is closed by a lid 20 equipped with a negative electrode terminal 16 and a positive electrode terminal 17.

Each electrode plate group 11 is formed by stacking a plurality of negative electrode plates 2 and positive electrode plates 3 with separators 4 interposed therebetween. Here, a bag-shaped separator 4 that houses the negative electrode plates 2 is shown, but the shape 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 that connects the plurality of negative electrode plates 2 in parallel is connected to the through connector 8, and the positive electrode shelf portion 5 that connects the plurality of positive electrode plates 3 in parallel is connected to the positive electrode column 7. The positive electrode column 7 is connected to a positive electrode terminal 17 outside the lid portion 20. 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 through connector 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 portion 20. Each through connector 8 passes through a through hole provided in the partition wall 13 to connect the electrode plate groups 11 of the adjacent cell chambers 14 in series.

The positive electrode shelf 5 is formed by welding the ears provided on the top of each positive electrode plate 3 together using a cast-on-strap method or a burning method. The negative electrode shelf 6 is also formed by welding the ears provided on the top of each negative electrode plate 2 together in the same manner as the positive electrode shelf 5.

The lid 20 includes a first lid 21 and a second lid 22. A lid having such a structure may be referred to as a "double lid". The second lid 22 is disposed on the outside of the first lid 21. The lid 20 has an exhaust port 20a. A filter may be disposed in the exhaust port 20a to prevent dust from entering the inside of the exterior body 10. The first lid 21 has an opening 18 formed to correspond to each cell chamber 14. A top view of an example of the first lid 21 is shown in FIG. 2A. A cross-sectional view taken along line IIB-IIB in FIG. 2A is shown in FIG. 2B, and a cross-sectional view taken along line IIC-IIC in FIG. 2A is shown in FIG. 2B and FIG. 2C. The second lid 22 attached to the first lid 21 is also shown in FIG. 2B and FIG. 2C. The lid 20 includes a portion for fixing the lid 20 to the battery case 12 and a portion for fixing the second lid 22 to the first lid 21, but these are not shown in the figure.

As shown in FIG. 2A, the lid portion 20 is formed with a gas flow path GP through which gas flows. The first lid 21 includes a plurality of gas flow path sections 21a, a plurality of through holes (circulation holes) 21b, and a plurality of vent holes (through holes) 21c. The plurality of gas flow path sections 21a, the plurality of through holes 21b, and the plurality of vent holes 21c are each formed to correspond to each cell chamber 14.

The gas flow passage section 21a includes a bottom surface section 21ab facing the gas flow passage GP and a wall section 21aw. The wall section 21aw is formed so as to increase the flow passage length of the gas flow passage section 21a. In the example shown in FIG. 2A to FIG. 2C, the wall section 21aw is formed only on the first lid 21, but the wall section 21aw may be formed only on the second lid 22, or may be formed on both the first lid 21 and the second lid 22. Of the surface of the second lid 22, the portion facing the gas flow passage GP functions as the gas flow passage section 22a (see FIG. 2B). As described above, the compound (C) is disposed on at least a portion of the surfaces of the gas flow passage sections 21a and 22a.

As shown in FIG. 2B, the bottom surface 21ab facing the gas flow path GP is inclined so that liquid condensed in the gas flow path flows toward the through hole 21b. The inclined bottom surface 21ab can also be considered as part of the circulation structure.

2C, the gas generated in the electrode plate group 11 of each cell chamber 14 passes through the vent hole 21c and the gas flow path GP. As shown in FIG. 2C, the wall between the through hole 21b and the vent hole 21c is formed to allow gas to pass through. All of the gas flow path sections 21a corresponding to each cell chamber 14 are connected to the exhaust port 20a. Therefore, at least a portion of the gas generated in the electrode plate group 11 is released to the outside of the exterior body 10 from the exhaust port 20a. As described above, the cover section 20 includes a gas flow path section that constitutes a gas flow path GP for releasing gas (e.g., hydrogen gas and oxygen gas) generated in the battery case 12 to the outside of the exterior body 10.

When gas passes through the gas flow passage, water vapor and electrolyte mist contained in the gas condense in the gas flow passage. The lead-acid battery of the present invention suppresses the decrease in electrolyte. This is believed to be because condensation in the gas flow passage is promoted by disposing compound (C) on at least a portion of the surface of the gas flow passage.

The lead-acid battery according to one aspect of the present invention is summarized below.

(1) A lead-acid battery,
The battery includes an electrolyte, an electrode assembly, and an exterior body,
The exterior body includes a battery case in which the electrolytic solution and the electrode plate group are accommodated, and a lid portion disposed at an opening of the battery case,
The lid portion includes a gas flow path portion that configures a gas flow path for releasing gas generated in the battery case to the outside of the exterior body,
the lid portion has a circulation structure for sending liquid condensed in the gas flow path into the battery container,
at least one compound selected from the group consisting of a compound having a hydrophilic group and a polymer compound is disposed on at least a portion of a surface of the gas flow path portion;
The lead-acid battery, wherein the polymer compound has a peak in the range of 3.2 ppm to 3.8 ppm in chemical shift of a ¹ H-NMR spectrum measured using deuterated chloroform as a solvent.

(2) A lead-acid battery,
The battery includes an electrolyte, an electrode assembly, and an exterior body,
The exterior body includes a battery case in which the electrolytic solution and the electrode plate group are accommodated, and a lid portion disposed at an opening of the battery case,
The lid portion includes a gas flow path portion that configures a gas flow path for releasing gas generated in the battery case to the outside of the exterior body,
the lid portion has a circulation structure for sending liquid condensed in the gas flow path into the battery container,
at least one compound selected from the group consisting of a compound having a hydrophilic group and a polymer compound is disposed on at least a portion of a surface of the gas flow path portion;
The polymer compound comprises a repeating structure of oxy-C _2-4 alkylene units.

(3) In the lead acid battery of (2) above, the polymer compound may include at least one selected from the group consisting of a hydroxy compound containing the repeating structure of the oxy _C2-4 alkylene unit, an etherified product of the hydroxy compound, and an esterified product of the hydroxy compound.

(4) In the lead acid battery according to any one of (1) to (3) above, the at least one compound may include the compound having the hydrophilic group. The compound having the hydrophilic group may be at least one selected from the group consisting of lignins, condensates containing a bisphenol unit, naphthalene derivatives, and condensates containing a phenolsulfonic acid unit.

(5) In any one of (1) to (4) above, the negative electrode material of the negative plate in the electrode group may contain the polymer compound.

(6) In the above (5), the content of the polymer compound in the negative electrode material may be in the range of 30 ppm to 500 ppm by mass.

(7) In any one of (1) to (6) above, the lid portion may include a first lid and a second lid. At least a portion of the second lid may be disposed outside the first lid. The portion of the first lid may constitute at least a portion of the gas flow path portion. The circulation structure may include a through hole formed in the first lid so that the condensed liquid is sent into the battery container.

[Example]
The present invention will be specifically described below based on examples and comparative examples, but the present invention is not limited to the following examples.

《Lead acid batteries A1 to A8, C1 to C9, B1》
(1) Preparation of lead-acid battery (a) Preparation of negative electrode plate Raw materials lead powder, barium sulfate, carbon black, an organic shrinkage inhibitor (sodium lignin sulfonate), and optionally a polymer compound (P) are mixed together. The polymer compound (P) is added to the negative electrode material so that the content of the polymer compound (P) in the negative electrode material is the content (mass basis) shown in Table 1. Similarly, the content of the organic shrinkage inhibitor in the negative electrode material is 0.1 mass %, the content of barium sulfate is 0.4 mass %, and the content of carbon black is 0.2 mass %. The components are mixed so that the mixture becomes uniform. The polymer compound (P) added to the negative electrode paste is polyoxyethylene oleate (molecular weight: 500). Next, the negative electrode paste is mixed with a Pb-Ca-Sn alloy The mixture is then filled into the mesh of an expanded lattice, and the mixture is aged and dried to obtain an unformed negative electrode plate.

(b) Preparation of Positive Plate The raw lead powder is mixed with an aqueous sulfuric acid solution to obtain a positive paste. The positive paste is filled into the mesh of an expanded lattice made of a Pb-Ca-Sn alloy, and aged and dried to obtain an unformed positive plate.

(c) Arrangement of compound (C) in gas flow passage For the lids of the batteries C1 and C4 to C6, a normal lid, not a double lid, is used. For the lids of the other batteries, a lid (double lid) composed of the first and second lids described above is used. Compound (C) is arranged on the surface of the gas flow passage of the lid by the following method. First, a liquid containing compound (C) is prepared. Liquid compound (C) may be used as is or may be diluted with a solvent. For solid compound (C), a liquid (solution or dispersion) containing compound (C) is prepared using a solvent. Next, the liquid is applied to the surface of the flow passage of the first lid described above and then dried. In this manner, compound (C) is arranged on the surface of the gas flow passage of the first lid.

As the compound (C), the following compound is used: In addition, in the battery C3, Daphne mechanic oil (industrial lubricating oil manufactured by Idemitsu Kosan Co., Ltd.) is used instead of the compound (C).
Battery B1: Formaldehyde condensation product of a bisphenol compound having a sulfonic acid group introduced therein (sulfur element content: 5000 μmol/g, Mw=9600) (bisphenol-based condensation product)
Batteries A1 to A4: Polypropylene glycol (PPG)
Batteries A5 to A8: Polyoxyethylene oleate (PEG ester) as above

(d) Preparation of Test Battery The test battery has a rated voltage of 2V and a rated 5-hour rate capacity of 32Ah. The plate group of the test battery is composed of seven positive plates and seven negative plates. The negative plates are housed in a pouch-shaped separator formed of a polyethylene microporous film and alternately stacked with the positive plates to form a plate group. The plate group is housed in a polypropylene battery case together with an electrolyte (aqueous sulfuric acid solution), and chemical formation is performed in the battery case to prepare a liquid-type lead-acid battery. The specific gravity of the electrolyte in a fully charged lead-acid battery at 20°C is 1.28. The above-mentioned lid is used as the lid that seals the battery case.

(2) Evaluation of the amount of electrolyte loss (amount of electrolyte loss) First, a high-temperature durability test is performed on the above test battery (lead-acid battery). Specifically, the above test battery is subjected to 5,000 charge-discharge cycles, with the following discharge and charge being one cycle, in a water tank at 75°C ± 3°C. The amount of electrolyte after 5,000 charge-discharge cycles is measured. The amount of electrolyte loss is calculated from the amount of electrolyte injected when preparing the test battery and the amount of electrolyte after the charge-discharge cycles. The amount of electrolyte loss of each battery is evaluated as a ratio (%) when the amount of electrolyte loss in the lead-acid battery C1 is taken as 100%.
Discharging: 25A, 2 minutes Charging: 14.8V, 25A, 10 minutes

Some of the manufacturing conditions and evaluation results are shown in Table 1.

The results of Table 1 are shown in Figure 3. The reduction in the amount of electrolyte (amount of electrolyte reduction) shown in Table 1 is preferably 75% or less. If the amount of electrolyte reduction is more than 75%, it cannot be said that a sufficient effect is obtained.

Here, we compare batteries C2, B1, A1, and A5, which do not contain the polymer compound (P) in the negative electrode material and have a double lid structure. In batteries B1, A1, and A5, which have compound (C) in the gas flow path, the amount of liquid loss can be sufficiently reduced. On the other hand, battery C2, which does not have compound (C) in the gas flow path, loses a large amount of liquid. Similarly, battery C3, which has oil in the gas flow path, loses a large amount of liquid. In addition, when comparing batteries B1, A1, and A5, battery A5, which uses an ester of polyalkylene glycol (e.g., PEG ester), loses less liquid.

The amount of liquid loss can be significantly reduced by adding a polymer compound (P) to the negative electrode material. Even in this case, the amount of liquid loss can be further reduced by placing a compound (C) in the gas flow path section. The amount of liquid loss can be particularly reduced by adding an esterified product of polyalkylene glycol (e.g., a PEG esterified product) to the negative electrode material and placing an esterified product of polyalkylene glycol (e.g., a PEG esterified product) in the gas flow path section.

The present invention can be used for lead-acid batteries. The lead-acid battery of the present invention is suitable for use in idle-stop vehicles, for example, as an IS lead-acid battery that is charged and discharged under PSOC conditions. In addition, the lead-acid battery can be suitably used, for example, as a starting power source for vehicles (cars, motorcycles, etc.) or as an industrial power storage device (for example, a power source for electric vehicles (forklifts, etc.)). Note that these uses are merely examples and are not limited to these uses.

1: Lead-acid battery 2: Negative electrode plate 3: Positive electrode plate 4: Separator 5: Positive electrode shelf 6: Negative electrode shelf 7: Positive electrode column 8: Through connector 9: Negative electrode column 10: Exterior body 11: Plate group 12: Battery case 13: Partition wall 14: Cell chamber 16: Negative electrode terminal 17: Positive electrode terminal 18: Opening 20: Lid 20a: Exhaust port 21: First lid 21a, 22a: Gas flow passage 21b: Through hole (circulation structure)
22: Second cover GP: Gas flow path

Claims (7)

The battery includes an electrolyte, an electrode assembly, and an exterior body,
The exterior body includes a battery case in which the electrolytic solution and the electrode plate group are accommodated, and a lid portion disposed at an opening of the battery case,
The lid portion includes a gas flow path portion that configures a gas flow path for releasing gas generated in the battery case to the outside of the exterior body,
the lid portion has a circulation structure for sending liquid condensed in the gas flow path into the battery container,
at least one compound selected from the group consisting of a compound having a hydrophilic group and a polymer compound is disposed on at least a portion of a surface of the gas flow channel;
The polymer compound has a peak in the range of 3.2 ppm to 3.8 ppm in chemical shift of a ¹ H-NMR spectrum measured using deuterated chloroform as a solvent. The battery includes an electrolyte, an electrode assembly, and an exterior body,
The exterior body includes a battery case in which the electrolytic solution and the electrode plate group are accommodated, and a lid portion disposed at an opening of the battery case,
The lid portion includes a gas flow path portion that configures a gas flow path for releasing gas generated in the battery case to the outside of the exterior body,
the lid portion has a circulation structure for sending liquid condensed in the gas flow path into the battery container,
at least one compound selected from the group consisting of a compound having a hydrophilic group and a polymer compound is disposed on at least a portion of a surface of the gas flow path portion;
The polymer compound comprises a repeating structure of oxy-C _2-4 alkylene units. The lead acid battery according to claim 2, wherein the polymer compound comprises at least one selected from the group consisting of a hydroxy compound containing the repeating structure of the oxy _C2-4 alkylene unit, an etherified product of the hydroxy compound, and an esterified product of the hydroxy compound. the at least one compound comprises the compound having the hydrophilic group,
The compound having the hydrophilic group is at least one selected from the group consisting of lignins, condensates containing a bisphenol unit, naphthalene derivatives, and condensates containing a phenolsulfonic acid unit. The lead acid battery according to any one of claims 1 to 3. The lead acid battery according to any one of claims 1 to 4, wherein the negative electrode material of the negative plate in the electrode plate group contains the polymer compound. The lead-acid battery according to claim 5, wherein the content of the polymer compound in the negative electrode material is in the range of 30 ppm to 500 ppm by mass. The lid portion includes a first lid and a second lid,
At least a portion of the second lid is disposed outside the first lid,
a portion of the first cover constitutes at least a portion of the gas flow path portion,
The lead-acid battery according to any one of claims 1 to 6, wherein the circulation structure includes a through hole formed in the first lid so that the condensed liquid is sent into the battery case.

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