Lead-acid battery

Abstract

This lead-acid battery comprises a negative electrode plate, a positive electrode plate, and an electrolyte solution. The negative electrode plate comprises a negative electrode material, and the positive electrode plate comprises a positive electrode current collector and a positive electrode material. The negative electrode material includes a polymer compound having a peak in the range of 3.2 ppm to 3.8 ppm inclusive in a 1H-NMR spectrum chemical shift measured using deuterated chloroform as a solvent. The polymer compound content in the negative electrode material by mass is 600 ppm or less. The arithmetic average roughness Ra of the surface of the positive electrode current collector is 2 μm or more.

Description

Technical Field

[0001] The present invention relates to a lead storage battery.

Background Art

[0002] Lead storage batteries are used in various applications, including in-vehicle and industrial applications. A lead storage battery includes a negative electrode plate, a positive electrode plate, a separator (or mat), and an electrolyte. Each electrode plate includes a current collector and an electrode material.

[0003] Regarding the positive current collector, Patent Document 1 proposes a foil for a positive current collector of a lead storage battery, which is made of titanium or a titanium alloy and has a surface roughness of 0.05 < Ra < 1.0 and 0.3 < Ry < 7.0 on at least one surface.

[0004] Patent Document 2 discloses a lead-acid battery including a positive electrode having a first surface and a second surface facing the first surface, and a negative electrode having a first surface and a second surface facing the first surface, wherein each of the positive electrode and the negative electrode is immersed in an electrolytic solution, and a fiber-attached mat that at least partially covers at least one of the first and second surfaces of at least one of the positive electrode and the negative electrode. The fiber-attached mat includes a plurality of fibers coated with a sizing composition, a binding composition, and one or more additives. Patent Document 2 proposes that the additive includes one or more of a rubber additive, a rubber derivative, an aldehyde, an aldehyde derivative, a metal salt, a fatty alcohol ethoxylate (an alkoxylated alcohol having a terminal OH group), an ethylene-propylene oxide block copolymer, a sulfate ester (an alkyl sulfate and an alkyl ether sulfate), a sulfonate ester (an alkyl and an olefin sulfonate), a phosphate ester, a sulfosuccinate, polyacrylic acid, polyaspartic acid, a perfluoroalkyl sulfonic acid, polyvinyl alcohol, lignin, a lignin derivative, a phenol-formaldehyde resin, cellulose, and wood flour, and that the additive reduces water loss in the lead-acid battery.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] As a factor for a lead-acid battery to reach the end of its life, it is known that the positive electrode active material softens and falls off due to repeated charge and discharge, leading to the end of its life. In particular, when deep discharge and charging are repeated, moss-like positive electrode active material that has fallen off due to softening is lifted by gas generation and deposited on the upper part of the electrode plate group, resulting in a short circuit (hereinafter referred to as "moss short circuit"), which may lead to the end of its life. Even in the usage form where the lead-acid battery is discharged until it reaches the deep discharge state, in order to realize a long-life lead-acid battery, it is necessary to effectively suppress this moss short circuit.

Means for Solving the Problem

[0007] The lead-acid battery according to one aspect of the present invention includes a negative electrode plate, a positive electrode plate, and an electrolytic solution. The negative electrode plate includes a negative electrode material, and the positive electrode plate includes a positive electrode current collector and a positive electrode material. The negative electrode material contains a polymer compound having a peak in the range of 3.2 ppm or more and 3.8 ppm or less in the chemical shift of the 1H-NMR spectrum measured using deuterated chloroform as a solvent. The content of the polymer compound in the negative electrode material is 600 ppm or less on a mass basis, and the arithmetic mean roughness Ra of the surface of the positive electrode current collector is 2 μm or more. 1 H-NMR spectrum has a peak in the range of 3.2 ppm or more and 3.8 ppm or less, and the content of the polymer compound in the negative electrode material is 600 ppm or less on a mass basis, and the arithmetic mean roughness Ra of the surface of the positive electrode current collector is 2 μm or more.

[0008] The lead-acid battery according to another aspect of the present invention includes a negative electrode plate, a positive electrode plate, and an electrolytic solution. The negative electrode plate includes a negative electrode material, and the positive electrode plate includes a positive electrode current collector and a positive electrode material. The negative electrode material contains a polymer compound including a repeating structure of oxyalkylene units. The content of the polymer compound in the negative electrode material is 600 ppm or less on a mass basis, and the arithmetic mean roughness Ra of the surface of the positive electrode current collector is 2 μm or more. 2-4 The negative electrode material contains a polymer compound including a repeating structure of oxyalkylene units. The content of the polymer compound in the negative electrode material is 600 ppm or less on a mass basis, and the arithmetic mean roughness Ra of the surface of the positive electrode current collector is 2 μm or more.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2A

Figure 2B

Mode for Carrying Out the Invention

[0010] One aspect of the present invention is a lead-acid battery, which includes a negative electrode plate, a positive electrode plate, and an electrolytic solution. The negative electrode plate includes a negative electrode active material. The positive electrode plate includes a positive electrode current collector and a positive electrode active material. The negative electrode active material contains a polymer compound having a peak in the range of 3.2 ppm or more and 3.8 ppm or less in the chemical shift of the 1H-NMR spectrum measured using deuterated chloroform as a solvent. The content of the polymer compound in the negative electrode active material is 600 ppm or less on a mass basis. The arithmetic mean roughness Ra of the surface of the positive electrode current collector is 2 μm or more. 1 In the chemical shift of the 1H-NMR spectrum, the peak appearing in the range of 3.2 ppm or more and 3.8 ppm or less is derived from an oxy C alkylene unit.

[0011] Note that the above 1 In the 1H-NMR spectrum, the peak appearing in the chemical shift range of 3.2 ppm or more and 3.8 ppm or less is 2-4 derived from an oxy C alkylene unit.

[0012] In a lead-acid battery, the softening and shedding of the positive electrode active material are considered to be due to the weakening of the bond between the positive electrode active material particles during charge and discharge, the decrease in the adhesion between the positive electrode active material and the positive electrode current collector, and the easy peeling of the positive electrode active material from the positive electrode current collector. Therefore, it is considered that by appropriately roughening the surface roughness of the positive electrode current collector, the adhesion between the active material and the current collector can be improved, and the shedding of the positive electrode active material can be suppressed. However, although the shedding of the positive electrode active material can be suppressed to some extent by roughening the surface roughness of the positive electrode current collector, since the amount of gas generation does not change, the effect of suppressing moss short circuit is small.

[0013] On the one hand, moss short circuit occurs when the softened and exfoliated moss-like positive electrode active material is rolled up to the upper part of the electrode plate group by the gas generated in an overcharged state or a state close to full charge. Therefore, for example, by suppressing gas generation, such as adding a gas generation suppressing material to the negative electrode material, moss short circuit can be suppressed. However, even if a gas generation suppressing material is added to the negative electrode material, the adhesion between the positive electrode active material and the current collector does not change, so the effect of suppressing moss short circuit was considered to be small.

[0014] However, as a result of intensive research, the inventors of the present application have found that by roughening the surface of the positive current collector and adding a polymer compound to the negative electrode material, when the surface roughness Ra of the positive current collector is 2 μm or more, moss short circuit is synergistically suppressed and the deep discharge cycle life is dramatically improved. Such findings are not described in the literature and are not even suggested.

[0015] The surface roughness Ra of the positive current collector should be 2 μm or more, preferably 4 μm or more, from the viewpoint of improving adhesion and suppressing peeling. On the other hand, the surface roughness Ra of the positive current collector is preferably 50 μm or less, more preferably 10 μm or less, in order to suppress the increase in the contact area with the electrolyte due to the increase in the surface area of the positive current collector and the easy progress of the corrosion of the positive current collector. The above upper and lower limits can be arbitrarily combined. The surface roughness Ra of the positive current collector is obtained by taking out the positive electrode plate from the lead storage battery, removing the positive electrode material as described later to expose the surface of the positive current collector, and measuring the arithmetic mean roughness Ra in a predetermined region of the surface of the positive current collector using a surface roughness meter.

[0016] Another aspect of the present invention is a lead storage battery including a negative electrode plate, a positive electrode plate, and an electrolyte. The negative electrode plate includes a negative electrode material. The positive electrode plate includes a positive current collector and a positive electrode material. The negative electrode material is oxy C 2-4The negative electrode material contains a polymer compound having a repeating structure of alkylene units. The content of the polymer compound in the negative electrode material is 600 ppm or less by mass. The arithmetic mean roughness Ra of the surface of the positive electrode current collector is 2 μm or more. Even in this configuration, by adding the polymer compound to the negative electrode material, moss short circuits are effectively suppressed and the deep discharge cycle life is dramatically improved.

[0017] In the lead-acid batteries according to one and the other aspects of the present invention, the addition of a polymer compound provides high deep discharge life performance for the following reasons.

[0018] The polymer compound is oxy C 2-4 Since the repeating structure of alkylene units makes it easy to form a linear structure, the surface of lead can be thinly and widely covered with a polymer compound in the negative electrode material. The hydrogen overvoltage increases when the surface of lead is covered with a polymer compound over a wide area of ​​the lead surface. This improves charge acceptance and makes it difficult for a side reaction to occur in which hydrogen is generated during overcharging or charging. As a result, gas generation is suppressed, and moss short circuit is unlikely to occur even when deep discharging and charging are repeated. In addition, even a very small amount of polymer compound can reduce the hydrogen generation reaction, so by including a polymer compound in the negative electrode material, it can be present in the vicinity of lead, which increases the hydrogen overvoltage. 2-4 The alkylene unit can exhibit a high adsorption effect on lead. In addition, by making the surface roughness Ra of the positive electrode current collector 2 μm or more, moss short circuit is synergistically suppressed, and a remarkably high deep discharge life performance is obtained.

[0019] The effect of the polymer compound as described above is exerted by the polymer compound covering the surface of lead. Therefore, it is important to have the polymer compound present in the vicinity of lead, whereby the effect of the polymer compound can be effectively exerted. Thus, regardless of whether the polymer compound is contained in components of the lead storage battery other than the negative electrode material, it is important that the negative electrode material contains the polymer compound.

[0020] The content of the polymer compound in the negative electrode material is preferably 600 ppm or less. In this case, it is possible to reduce the risk that the film of the polymer compound covering the surface of lead becomes thick and the charge acceptance decreases conversely. The content of the polymer compound in the negative electrode material may be 30 ppm or more and 500 ppm or less on a mass basis. According to these aspects of the present invention, when the content of the polymer compound is within this range, the effect of improving the deep discharge cycle life is more remarkable.

[0021] Here, in the lead storage battery according to these aspects of the present invention, the polymer compound may contain an oxygen atom bonded to a terminal group, and a -CH2- group and / or a -CH< group bonded to the oxygen atom. 1 In the 1H-NMR spectrum, the ratio of the integral value of the peak in the range of 3.2 ppm to 3.8 ppm to the total of the integral value of the peak of the hydrogen atom of the -CH2- group bonded to the oxygen atom and the integral value of the peak of the hydrogen atom of the -CH< group bonded to the oxygen atom is preferably 85% or more. Such a polymer compound contains many oxyC 2-4 alkylene units in the molecule. Therefore, it is considered that the polymer compound is likely to adsorb to lead and is more likely to take a linear structure, so that it is easy to thinly cover the lead surface. Thus, the gas generation amount is likely to be reduced, and the effect of improving the deep discharge cycle life can be enhanced.

[0022] Here, 1 In the 1H-NMR spectrum, a polymer compound having a peak in the chemical shift range of 3.2 ppm to 3.8 ppm is oxyC 2-4It may contain a repeating structure of an alkylene unit. According to these aspects of the present invention, when using a polymer compound containing a repeating structure of an oxy C 2-4 When using a polymer compound containing a repeating structure of an alkylene unit, it is considered that the polymer compound becomes more likely to adsorb to lead and is likely to take a linear structure, making it easier to thinly cover the lead surface. Therefore, the gas generation amount is more likely to be reduced, and the effect of improving the deep discharge cycle life can be further enhanced.

[0023] Here, the polymer compound contains at least one selected from the group consisting of a hydroxy compound having a repeating structure of an oxy C 2-4 alkylene unit, an etherified product of a hydroxy compound, and an esterified product of a hydroxy compound. The hydroxy compound may be at least one selected from the group consisting of poly C 2-4 alkylene glycol, a copolymer containing a repeating structure of oxy C 2-4 alkylene, and a poly C 2-4 alkylene oxide adduct of a polyol. According to these aspects of the present invention, when using such a polymer compound, the gas generation amount is more likely to be further reduced, and the effect of improving the deep discharge cycle life is high.

[0024] The polymer compound may contain a repeating structure of an oxypropylene unit (-O-CH(-CH3)-CH2-). Such a polymer compound is considered to have an excellent balance in that while having a high adsorptivity to lead, it is suppressed from thickly adhering to the lead surface. Therefore, the gas generation amount can be more effectively reduced, and the effect of improving the deep discharge cycle life can be further enhanced.

[0025] The polymer compound has one or more hydrophobic groups, and at least one of the hydrophobic groups may be a long-chain aliphatic hydrocarbon group having 8 or more carbon atoms. Due to the action of such a hydrophobic group, excessive coating of the polymer compound on the lead surface is suppressed, making it easy to achieve both suppression of the decrease in charge acceptance and reduction of the gas generation amount.

[0026] The polymer compound preferably contains a repeating structure of oxyethylene units. By including a repeating structure of oxyethylene units in which the polymer compound has high hydrophilicity, the polymer compound can be selectively adsorbed onto lead. Due to the balance between the hydrophobic group and the hydrophilic group, the amount of gas generation can be more effectively reduced, and the effect of improving the deep discharge cycle life can be further enhanced. As such a polymer compound, at least one selected from the group consisting of polyethylene glycol oleate, polyethylene glycol dilaurate, polyethylene glycol distearate, and polyethylene glycol dioleate may be used.

[0027] In a lead storage battery, it is sufficient that the polymer compound can be contained in the negative electrode material, and the origin of the polymer compound contained in the negative electrode material is not particularly limited. The polymer compound may be contained in any of the components of the lead storage battery (for example, the negative electrode plate, the positive electrode plate, the electrolyte, and the separator) when manufacturing the lead storage battery. The polymer compound may be contained in one component, or may be contained in two or more components (for example, the negative electrode plate and the electrolyte).

[0028] The lead storage battery may be either a controlled valve type (sealed type) lead storage battery (VRLA type lead storage battery) or a liquid type (vented type) lead storage battery.

[0029] In this specification, the surface roughness of the positive electrode current collector, the average pore diameter of the negative electrode material, the respective contents of the polymer compound and the organic shrinkage inhibitor in the negative electrode material, and the bulk density of the negative electrode material are determined for the negative electrode plate taken out from the fully charged lead storage battery.

[0030] (Explanation of Terms) (Electrode Material) Each of the negative electrode material and the positive electrode material is usually held by a current collector. The electrode material is the part excluding the current collector from the electrode plate. Members such as a mat and a pasting paper may be attached to the electrode plate. Since such a member (also referred to as an attachment member) is used integrally with the electrode plate, it is considered to be included in the electrode plate. When the electrode plate includes an attachment member (such as a mat or a pasting paper), the electrode material is the part excluding the current collector and the attachment member from the electrode plate.

[0031] Among the positive electrode plates, the clad type positive electrode plate includes a plurality of porous tubes, a core (spine) inserted into each tube, a current collecting portion connecting the plurality of cores (spines), a positive electrode material filled in the tube into which the core (spine) is inserted, and a connecting seat (spine protector) connecting the plurality of tubes. In the clad type positive electrode plate, the positive electrode material is the one excluding the tube, the core (spine), the current collecting portion, and the connecting seat (spine protector). In the clad type positive electrode plate, the core (spine) and the current collecting portion may be collectively referred to as a positive electrode current collector.

[0032] (Surface roughness) The surface roughness Ra of the positive electrode current collector is the arithmetic mean roughness Ra defined in JIS B 0601:2001. The arithmetic mean roughness Ra is measured using a surface roughness meter for the positive electrode current collector whose surface is exposed by removing the positive electrode material from the positive electrode plate of the lead storage battery by the following procedure. For example, the arithmetic mean roughness Ra can be measured using the "VK-X100 LASER MICROSCOPE" manufactured by Keyence Corporation.

[0033] First, disassemble the lead storage battery to take out the positive electrode plate. Subject the taken-out positive electrode plate to a mannite treatment to remove the positive electrode material from the positive electrode plate. Then, obtain a positive electrode current collector from which the positive electrode material has been removed by washing with water.

[0034] The positive current collector is divided into three parts in the vertical direction and three parts in the horizontal direction, respectively, to be divided into a total of nine regions (it is not necessarily required to cut the positive electrode plate to divide it into the above nine regions). For each of the nine regions, at least one relatively flat measurement target location is arbitrarily selected, and the arithmetic mean roughness Ra of the surface at the measurement target location is measured. The average value of the arithmetic mean roughness Ra of nine or more locations measured by the above method is defined as the surface roughness Ra of the positive current collector. The measurement target locations include portions corresponding to the horizontal ribs and vertical ribs of the current collector.

[0035] (Polymer compound) The polymer compound satisfies at least one of the following conditions (i) and (ii). Condition (i) The polymer compound has a peak in the range of 3.2 ppm or more and 3.8 ppm or less in the chemical shift of the 1H-NMR spectrum measured using deuterated chloroform as a solvent. 1 Condition (ii) The polymer compound contains a repeating structure of oxy-C 2-4 alkylene units. In the above (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 units. That is, a polymer compound satisfying condition (ii) is also a polymer compound satisfying condition (i). A polymer compound satisfying condition (i) may contain a repeating structure of monomer units other than the oxy-C 2-4 alkylene units and may have a certain molecular weight. The number average molecular weight (Mn) of the polymer compound satisfying the above (i) or (ii) may be, for example, 300 or more.

[0036] (Oxy-C 2-4 alkylene units) Oxy-C 2-4 alkylene units are units represented by -O-R 1 -(R 1 represents a C 2-4 alkylene group.)

[0037] (Organic anti-shrinkage agent) An organic anti-shrinkage agent refers to an organic compound among compounds having a function of suppressing the shrinkage of lead, which is a negative electrode active material, when the charge and discharge of a lead-acid battery are repeated.

[0038] (Number average molecular weight) In this specification, the number average molecular weight (Mn) is determined by gel permeation chromatography (GPC). The standard substance used when determining Mn is polyethylene glycol.

[0039] (Fully charged state) The fully charged state of a flooded lead-acid battery is defined by JIS D 5301:2019. More specifically, in a water tank at 25°C ± 2°C, with a current (A) of 0.2 times the value described as the rated capacity (a value with the unit of Ah), the terminal voltage (V) during charging measured every 15 minutes or the electrolyte density converted to 20°C shows a constant value with three significant figures for three consecutive times. The state where the lead-acid battery is charged until then is defined as the fully charged state. Also, in the case of a valve-regulated lead-acid battery, the fully charged state means that in an air tank at 25°C ± 2°C, with a current (A) of 0.2 times the value described as the rated capacity (a value with the unit of Ah), constant current constant voltage charging is performed at 2.23 V / cell, and the charging is terminated when the charging current during constant voltage charging reaches a value (A) of 0.005 times the value described as the rated capacity (a value with the unit of Ah).

[0040] A fully charged lead-acid battery refers to a lead-acid battery obtained by fully charging a preformed lead-acid battery. The full charge of a lead-acid battery may be immediately after formation if it is after formation, or may be performed after a certain period of time has elapsed since formation (for example, after formation, a lead-acid battery during use (preferably in the initial stage of use) may be fully charged). The battery in the initial stage of use refers to a battery that has not elapsed much time since the start of use and has hardly deteriorated.

[0041] (Vertical direction of a lead-acid battery or a component of a lead-acid battery) In this specification, the vertical direction of a lead-acid battery or its components (such as electrode plates, battery cases, separators, etc.) means the vertical up-and-down direction of the lead-acid battery when it is in use. Each of the positive and negative electrode plates is provided with an ear for connection to an external terminal. In some cases, such as in a horizontally placed controlled valve type lead-acid battery, the ear may be provided to protrude laterally from the side of the electrode plate, but in many lead-acid batteries, the ear is usually provided to protrude upward from the upper part of the electrode plate.

[0042] Hereinafter, the lead-acid battery according to the embodiment of the present invention will be described for each main component, but the present invention is not limited to the following embodiments.

[0043] [Lead-acid battery] (Negative electrode plate) The negative electrode plate usually includes a negative electrode current collector in addition to the negative electrode active material.

[0044] (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 expansion processing or punching processing. It is preferable to use a grid-like current collector as the negative electrode current collector because it is easy to carry the negative electrode active material.

[0045] The lead alloy used for the negative electrode current collector may be any of a Pb-Sb based alloy, a Pb-Ca based alloy, and a Pb-Ca-Sn based alloy. These leads 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 be provided with a surface layer. The composition of the surface layer and the inner layer of the negative electrode current collector may be different. The surface layer may be formed on a part of the negative electrode current collector. The surface layer may be formed on the ear of the negative electrode current collector. The surface layer of the ear may contain Sn or an Sn alloy.

[0046] (Negative electrode active material) The negative electrode material contains the above polymer compound. The negative electrode material further contains a negative electrode active material (specifically, lead or lead sulfate) that exhibits capacitance through a redox reaction. The negative electrode material may further contain an organic anti-shrinkage agent. The negative electrode material may contain at least one selected from the group consisting of a carbonaceous material and other additives. Examples of the additive include, but are not limited to, barium sulfate, fibers (such as resin fibers). Note that the negative electrode active material in the charged state is spongy lead, but the unformed negative electrode plate is usually produced using lead powder.

[0047] (Polymer compound) The polymer compound 1 has a peak in the range of 3.2 ppm or more and 3.8 ppm or less in the chemical shift of the H-NMR spectrum. Such a polymer compound has an oxy C 2-4 alkylene unit. The oxy C 2-4 alkylene units include oxyethylene unit, oxypropylene unit, oxytrimethylene unit, oxy 2-methyl-1,3-propylene unit, oxy 1,4-butylene unit, oxy 1,3-butylene unit, etc. The polymer compound may have one kind of such oxy C 2-4 alkylene unit or two or more kinds of such alkylene units.

[0048] The polymer compound preferably contains a repeating structure of an oxy C 2-4 alkylene unit. The repeating structure may contain one kind of oxy C 2-4 alkylene unit or two or more kinds of oxy C 2-4 alkylene units. The polymer compound may contain one kind of the above repeating structure or two or more kinds of the above repeating structures.

[0049] Oxy C 2-4 The polymer compound having a repeating structure of an alkylene unit includes a polymer compound classified as a surfactant (more specifically, a nonionic surfactant).

[0050] Examples of the polymer compound include, for example, hydroxy compounds having a repeating structure of oxy C 2-4 alkylene units (poly C 2-4 alkylene glycol, copolymer containing a repeating structure of oxy C 2-4 alkylene, poly C of polyol 2-4 alkylene oxide adducts, etc.), etherified products or esterified products of these hydroxy compounds, and the like.

[0051] Examples of the copolymer include copolymers containing different oxy C 2-4 alkylene units, etc. The copolymer may be a block copolymer.

[0052] The polyol may be any of aliphatic polyols, alicyclic polyols, aromatic polyols, and heterocyclic polyols. From the viewpoint that the polymer compound easily spreads thinly on the lead surface, aliphatic polyols, alicyclic polyols (for example, polyhydroxycyclohexane, polyhydroxynorbornane), etc. are preferable, and among them, aliphatic polyols are preferable. Examples of the aliphatic polyol include aliphatic diols, polyols having three or more hydroxyl groups (for example, glycerin, trimethylolpropane, pentaerythritol, sugar or sugar alcohol), etc. Examples of the aliphatic diol include alkylene glycols having 5 or more carbon atoms. The alkylene glycol may be, for example, C 5~14 alkylene glycol or C 5-10 alkylene glycol. Examples of the sugar or sugar alcohol include erythritol, xylitol, mannitol, sorbitol, etc. The sugar or sugar alcohol may have either a chain structure or a cyclic structure. In the polyalkylene oxide adduct of the polyol, the alkylene oxide corresponds to the oxy C 2-4 alkylene unit of the polymer compound and is at least C 2-4It contains an alkylene oxide. From the perspective that the polymer compound is likely to have a linear structure, the polyol is preferably a diol.

[0053] The etherified product is the above oxy C 2-4 At least a part of the -OH groups (the -OH groups composed of the hydrogen atom of the terminal group and the oxygen atom bonded to this hydrogen atom) at the terminals of the hydroxy compound having a repeating structure of alkylene units are etherified -OR 2 groups (wherein R 2 is an organic group). Among the terminals of the polymer compound, some terminals may be etherified, or all terminals may be etherified. For example, one terminal of the main chain of a linear polymer compound may be an -OH group and the other terminal may be an -OR 2 group.

[0054] The esterified product is the above oxy C 2-4 At least a part of the -OH groups (the -OH groups composed of the hydrogen atom of the terminal group and the oxygen atom bonded to this hydrogen atom) at the terminals of the hydroxy compound having a repeating structure of alkylene units are esterified -O-C(=O)-R 3 groups (wherein R 3 is an organic group). Among the terminals of the polymer compound, some terminals may be esterified, or all terminals may be esterified. For example, one terminal of the main chain of a linear polymer compound may be an -OH group and the other terminal may be an -O-C(=O)-R 3 group.

[0055] The organic group R 2 and R 3Examples of each include hydrocarbon groups. The hydrocarbon group may have substituents (such as a hydroxy group, an alkoxy group, and / or a carboxy group, etc.). 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 (such as 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, may be 1 to 20, may be 1 to 10, or may be 1 to 6 or 1 to 4.

[0056] Examples of the aromatic hydrocarbon group include aromatic hydrocarbon groups having 24 or fewer carbon atoms (such as 6 to 24). The number of carbon atoms of the aromatic hydrocarbon group may be 20 or fewer (such as 6 to 20), may be 14 or fewer (such as 6 to 14), or may be 12 or fewer (such as 6 to 12). Examples of the aromatic hydrocarbon group include an aryl group, a bisaryl group, etc. Examples of the aryl group include a phenyl group, a naphthyl group. Examples of the bisaryl group include a monovalent group corresponding to bisarene. Examples of bisarene include biphenyl, bisarylalkane (such as 2,2-bis(phenyl)propane, etc.). 6-10 aryl C 1-4 alkane (such as 2,2-bis(phenyl)propane)) are included.

[0057] Examples of the alicyclic hydrocarbon group include alicyclic hydrocarbon groups having 16 or fewer carbon atoms. The alicyclic hydrocarbon group may be a bridged cyclic hydrocarbon group. The number of carbon atoms of the alicyclic hydrocarbon group may be 10 or fewer or 8 or fewer. The number of carbon atoms of the alicyclic hydrocarbon group may be, for example, 5 or more, and may be 6 or more.

[0058] The number of carbon atoms of the alicyclic hydrocarbon group may be 5 (or 6) or more and 16 or less, 5 (or 6) or more and 10 or less, or 5 (or 6) or more and 8 or less.

[0059] Examples of the alicyclic hydrocarbon group include cycloalkyl groups (such as cyclopentyl group, cyclohexyl group, cyclooctyl group, etc.), cycloalkenyl groups (such as cyclohexenyl group, cyclooctenyl group, etc.), and the like. The alicyclic hydrocarbon group also includes hydrogenated products of the above aromatic hydrocarbon groups.

[0060] From the viewpoint that the polymer compound easily adheres thinly to the lead surface, among the hydrocarbon groups, an aliphatic hydrocarbon group is preferable. The aliphatic hydrocarbon group may be saturated or unsaturated. Examples of the aliphatic hydrocarbon group include alkyl groups, alkenyl groups, alkynyl groups, dienyl groups having two carbon-carbon double bonds, trienyl groups having three carbon-carbon double bonds, and the like. The aliphatic hydrocarbon group may be either linear or branched.

[0061] The number of carbon atoms of the aliphatic hydrocarbon group is, for example, 30 or less, and may be 26 or less, 22 or less, 20 or less, 16 or less, 14 or less, 10 or less, 8 or less, or 6 or less. The lower limit of the number of carbon atoms depends on the type of the aliphatic hydrocarbon group, being 1 or more for an alkyl group, 2 or more for an alkenyl group and an alkynyl group, 3 or more for a dienyl group, and 4 or more for a trienyl group. Among them, alkyl groups and alkenyl groups are preferable from the viewpoint that the polymer compound easily adheres thinly to the lead surface.

[0062] Specific examples of the alkyl group include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl, neopentyl, i-pentyl, 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, heneicosyl, behenyl.

[0063] Specific examples of the alkenyl group include vinyl, 1-propenyl, allyl, cis-9-heptadecen-1-yl, palmitoleyl, and oleyl. The alkenyl group is, for example, C 2-30 an alkenyl group or C 2-26 may be an alkenyl group, C 2-22 an alkenyl group or C 2-20 may be an alkenyl group, C 10-20 may be an alkenyl group.

[0064] Among the polymer compounds, it is preferable to use 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, because gas generation is suppressed and the effect of suppressing the decrease in charge acceptance can be further enhanced. In addition, the amount of gas generation can also be reduced when these polymer compounds are used. Among such polymer compounds, polymer compounds having a repeating structure of oxypropylene units or polymer compounds having a repeating structure of oxyethylene units are preferable.

[0065] The polymer compound may have one or more hydrophobic groups. Examples of the hydrophobic group include aromatic hydrocarbon groups, alicyclic hydrocarbon groups, and long-chain aliphatic hydrocarbon groups among the above hydrocarbon groups. Examples of the long-chain aliphatic hydrocarbon group include aliphatic hydrocarbon groups (such as alkyl groups and alkenyl groups) having 8 or more carbon atoms among the above aliphatic hydrocarbon groups. The number of carbon atoms of the aliphatic hydrocarbon group is preferably 12 or more, and more preferably 16 or more. Among them, a polymer compound having a long-chain aliphatic hydrocarbon group is preferable because it is difficult to cause excessive adsorption to lead and the effect of suppressing the decrease in charge acceptance is further enhanced. The polymer compound may be a polymer compound in which at least one of the hydrophobic groups is a long-chain aliphatic hydrocarbon group. The number of carbon atoms of the long-chain aliphatic hydrocarbon group may be 30 or less, 26 or less, or 22 or less.

[0066] 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.

[0067] Among the polymer compounds, the polymer compound having a hydrophilic group and a hydrophobic group corresponds to a nonionic surfactant. The repeating structure of the oxyethylene unit exhibits high hydrophilicity and can serve as the hydrophilic group in the nonionic surfactant. Therefore, the polymer compound having the above hydrophobic group preferably contains the repeating structure of the oxyethylene unit. Such a polymer compound can suppress excessive coverage of the lead surface while selectively adsorbing to lead due to the balance between hydrophobicity and high hydrophilicity due to the repeating structure of the oxyethylene unit, so that while reducing the gas generation amount, the effect of suppressing the decrease in charge acceptance can be further enhanced. Such a polymer compound can ensure high adsorptivity to lead even with a relatively low molecular weight (for example, Mn is 1000 or less).

[0068] Among the above polymer compounds, polyoxypropylene-polyoxyethylene block copolymers, etherified products of hydroxy compounds having a repeating structure of oxyethylene units, esterified products of hydroxy compounds having a repeating structure of oxyethylene units, etc. correspond to nonionic surfactants.

[0069] In the case of polyoxypropylene-polyoxyethylene block copolymers, etc., the repeating structure of the oxyethylene unit corresponds to the hydrophilic group, and the repeating structure of the oxypropylene unit corresponds to the hydrophobic group. Such copolymers are also included in the polymer compounds having a hydrophobic group.

[0070] Examples of the polymer compound having a hydrophobic group and including 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 (triols or higher polyols, etc.) (such as carboxylic acid esters). Specific examples of such polymer compounds 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. However, the polymer compound is not limited to these. Among them, it is preferable to use esterified products of polyethylene glycol, esterified products of polyethylene oxide adducts of the above polyols, etc., because higher charge acceptance can be ensured and the gas generation amount can be significantly reduced.

[0071] Among the polymer compounds classified as surfactants, from the viewpoint of being more likely to further reduce the reduction amount of the electrolytic solution, the HLB of the polymer compound is preferably 4 or more, more preferably 4.3 or more. From the viewpoint of being more likely to ensure higher charge acceptance, the HLB of the polymer compound is preferably 18 or less, more preferably 10 or less or 9 or less, and even more preferably 8.5 or less.

[0072] The HLB of the polymer compound may be 4 or more (or 4.3 or more) and 18 or less, or 4 or more (or 4.3 or more) and 10 or less. From the viewpoint of excellent balance between gas generation amount reduction and charge acceptance improvement, the HLB of the polymer compound is preferably 4 or more (or 4.3 or more) and 9 or less, or 4 or more (or 4.3 or more) and 8.5 or less.

[0073] From the viewpoint of further enhancing the effect of suppressing gas generation and more easily ensuring high charge acceptance, oxy C 2-4 It is also preferable that the repeating structure of the alkylene contains at least the repeating structure of the oxypropylene unit. In this case, compared with the case of the repeating structure of the oxyethylene unit, the charge acceptance tends to be lower. However, even in this case, it is possible to ensure high charge acceptance while keeping the gas generation amount low. The polymer compound containing an oxypropylene unit has, 1 In the chemical shift of the 1H-NMR spectrum, peaks derived from -CH and -CH2- of the oxypropylene unit are present in the range of 3.2 ppm to 3.8 ppm. Since the electron density around the nuclei of the hydrogen atoms in these groups is different, the peaks are in a split state. Such a polymer compound has, 1 In the chemical shift of the 1H-NMR spectrum, for example, peaks are present in each of the range of 3.2 ppm or more and 3.42 ppm or less, and the range of more than 3.42 ppm and 3.8 ppm or less. The peak in the range of 3.2 ppm or more and 3.42 ppm or less is derived from -CH2-, and the peak in the range of more than 3.42 ppm and 3.8 ppm or less is derived from -CH and -CH2-.

[0074] Examples of the polymer compound containing at least the repeating structure of the oxypropylene unit include polypropylene glycol, a copolymer containing the repeating structure of the oxypropylene unit, a polypropylene oxide adduct of the above polyol, or an etherified product or esterified product thereof. Examples of the copolymer include an oxypropylene-oxyalkylene copolymer (however, the oxyalkylene is a C other than oxypropylene), 2-4Examples include (alkylene). Examples of the oxypropylene-oxyalkylene copolymer include an oxypropylene-oxyethylene copolymer and an oxypropylene-oxytrimethylene copolymer. The oxypropylene-oxyalkylene copolymer may be referred to as a polyoxypropylene-polyoxyalkylene copolymer (for example, a polyoxypropylene-polyoxyethylene copolymer). The oxypropylene-oxyalkylene copolymer may be a block copolymer (for example, a polyoxypropylene-polyoxyethylene block copolymer). Examples of the etherified product include polypropylene glycol alkyl ether and alkyl ether of oxypropylene-oxyalkylene copolymer (such as alkyl ether of polyoxypropylene-polyoxyethylene copolymer). Examples of the esterified product include polypropylene glycol ester of carboxylic acid and carboxylic acid ester of oxypropylene-oxyalkylene copolymer (such as carboxylic acid ester of polyoxypropylene-polyoxyethylene copolymer).

[0075] Examples of the polymer compound containing at least a repeating structure of an oxypropylene unit include, for example, polypropylene glycol, polyoxypropylene-polyoxyethylene copolymer (such as polyoxypropylene-polyoxyethylene block copolymer), polyoxyethylene-polyoxypropylene alkyl ether (alkyl ether in which R2 above is an alkyl having 10 or less carbon atoms (or 8 or less or 6 or less) (such as butyl ether)), polypropylene glycol carboxylic acid (where R 3 is a polypropylene glycol carboxylic acid in which the alkyl has 10 or less carbon atoms (or 8 or less or 6 or less) (such as polypropylene glycol acetate)), polypropylene oxide adduct of a polyol having three or more hydroxyl groups (such as polypropylene oxide adduct of glycerin). However, the polymer compound is not limited thereto.

[0076] In a polymer compound 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.

[0077] In a polymer compound 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).

[0078] From the viewpoint that the adsorbability of the polymer compound to lead increases and the polymer compound is likely to have a linear structure, the polymer compound preferably contains many oxyC 2-4 alkylene units. Such a polymer compound contains, for example, an oxygen atom bonded to a terminal group, and a -CH2- group and / or a -CH< group bonded to the oxygen atom. In the 1 1H-NMR spectrum of the polymer compound, the ratio of the integral value of the peak at 3.2 ppm to 3.8 ppm to the total of the integral values of the peaks of the hydrogen atoms of the -CH2- group and the integral values of the peaks of the hydrogen atoms of the -CH< group increases. This ratio is, for example, 50% or more, and may be 80% or more. From the viewpoint that the effect of reducing the gas generation amount is further enhanced and it is easier to ensure higher charge acceptance, the above ratio is preferably 85% or more, and more preferably 90% or more. For example, when the polymer compound has an -OH group at the terminal and has a -CH2- group and / or a -CH< group bonded to the oxygen atom of this -OH group,1 In the 1H-NMR spectrum, the peaks of the hydrogen atoms of the -CH2- group and the -CH< group are in the range where the chemical shift exceeds 3.8 ppm and is 4.0 ppm or less.

[0079] The negative electrode material may contain one kind of polymer compound or may contain two or more kinds of polymer compounds.

[0080] The polymer compound may contain, for example, a compound having a Mn of 5 million or less, a compound having a Mn of 3 million or less or 2 million or less, a compound having a Mn of 500,000 or less or 100,000 or less, or a compound having a Mn of 50,000 or less or 20,000 or less. From the viewpoint of reducing the thickness of the film of the polymer compound covering the surfaces of lead and lead sulfate and ensuring higher charge acceptance, the polymer compound preferably contains a compound having a Mn of 10,000 or less, and may contain a compound having a Mn of 5,000 or less or 4,000 or less, or a compound having a Mn of 3,000 or less or 2,500 or less. From the viewpoint of further enhancing the effect of reducing the gas generation amount, the Mn of such a compound is preferably 300 or more and 10,000 or less. As the polymer compound, two or more kinds of compounds having different Mn may be used. That is, the polymer compound may have a plurality of Mn peaks in the molecular weight distribution.

[0081] The content of the polymer compound in the negative electrode material is, for example, 8 ppm or more on a mass basis, and may be 10 ppm or more. From the viewpoint of reducing the gas generation amount and increasing the deep discharge cycle life, the content of the polymer compound in the negative electrode material is preferably 20 ppm or more on a mass basis, and more preferably 30 ppm or more. The content of the polymer compound in the negative electrode material is 600 ppm or less on a mass basis from the viewpoint of maintaining high charge acceptance, and may be 500 ppm or less. From the viewpoint of easily ensuring higher charge acceptance, the content of the polymer compound in the negative electrode material is preferably 400 ppm or less on a mass basis, and more preferably 300 ppm or less.

[0082] The content (by mass) of the polymer compound in the negative electrode material may be 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 10 ppm or more) and 400 ppm or less, 8 ppm or more (or 10 ppm or more) and 300 ppm or less, 20 ppm or more (or 30 ppm or more) and 600 ppm or less, 20 ppm or more (or 30 ppm or more) and 500 ppm or less, 20 ppm or more (or 30 ppm or more) and 400 ppm or less, or 20 ppm or more (or 30 ppm or more) and 300 ppm or less.

[0083] (Organic anti-shrinkage agent) Organic anti-shrinkage agents are generally classified into lignin compounds and synthetic organic anti-shrinkage agents. Synthetic organic anti-shrinkage agents can also be said to be organic anti-shrinkage agents other than lignin compounds. Examples of the organic anti-shrinkage agent contained in the negative electrode material include lignin compounds and synthetic organic anti-shrinkage agents. The negative electrode material may contain one kind of organic anti-shrinkage agent or two or more kinds.

[0084] Examples of the lignin compound include lignin and lignin derivatives. Examples of the lignin derivative include lignin sulfonic acid or its salts (such as alkali metal salts (sodium salts, etc.)).

[0085] The synthetic organic anti-shrinkage agent is an organic polymer containing sulfur element. Generally, it contains a plurality of aromatic rings in the molecule and contains sulfur element as a sulfur-containing group. Among the sulfur-containing groups, a sulfonic acid group or a sulfonyl group in a stable form is preferable. The sulfonic acid group may exist in an acid form or in a salt form such as a Na salt.

[0086] At least a lignin compound may be used as the organic anti-shrinkage agent. When a lignin compound is used, the charge acceptance tends to be lower compared to the case where a synthetic organic anti-shrinkage agent is used. However, since the negative electrode material contains a specific polymer compound, even when a lignin compound is used as the organic anti-shrinkage agent, the decrease in charge acceptance can be suppressed and high charge acceptance can be ensured.

[0087] It is also preferable to use a condensate containing at least a unit of an aromatic compound as the organic shrinkage inhibitor. Examples of such condensates include condensates of aromatic compounds with aldehyde compounds (such as at least one selected from the group consisting of aldehydes (e.g., formaldehyde) and their condensates). The organic shrinkage inhibitor may contain a unit of one kind of aromatic compound or may contain units of two or more kinds of aromatic compounds. The unit of the aromatic compound refers to a unit derived from the aromatic compound incorporated into the condensate.

[0088] Examples of the aromatic ring of the aromatic compound include a benzene ring and a naphthalene ring. When the aromatic compound has a plurality of aromatic rings, the plurality of aromatic rings may be directly bonded or linked by a linking group (e.g., an alkylene group (including an alkylidene group), a sulfone group, etc.). Examples of such a structure include a bisarene structure (biphenyl, bisphenylalkane, bisphenylsulfone, etc.). Examples of the aromatic compound include a compound having at least one selected from the group consisting of the above aromatic ring and a hydroxy group and an amino group. The hydroxy group or the amino group may be directly bonded to the aromatic ring or may be bonded as an alkyl chain having a hydroxy group or an amino group. The hydroxy group also includes a salt of the hydroxy group (-OMe). The amino group also includes a salt of the amino group (specifically, a salt with an anion). Examples of Me include an alkali metal (Li, K, Na, etc.), a Group 2 metal of the periodic table (Ca, Mg, etc.).

[0089] As the aromatic compound, bisarene compounds [bisphenol compounds, hydroxybiphenyl compounds, bisarene compounds having an amino group (bisaralkylalkane 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 anti-shrinkage agent may contain one kind of the residues of these compounds or a plurality of kinds. As the bisphenol compound, bisphenol A, bisphenol S, bisphenol F, etc. are preferred.

[0090] The condensate preferably contains at least a unit of an aromatic compound having a sulfur-containing group. Among them, using a condensate containing at least a unit of a bisphenol compound having a sulfur-containing group is advantageous for ensuring higher charge acceptance. From the viewpoint of enhancing the effect of reducing the overcharge amount of electricity, it is also preferable to use a condensate formed from an aldehyde compound of a naphthalene compound having a sulfur-containing group and at least one selected from the group consisting of a hydroxy group and an amino group.

[0091] The sulfur-containing group may be directly bonded to the aromatic ring contained in the compound, and for example, it may be bonded to the aromatic ring as an alkyl chain having a sulfur-containing group. The sulfur-containing group is not particularly limited, and examples thereof include a sulfonyl group, a sulfonic acid group or a salt thereof.

[0092] Further, as the organic shrinkage inhibitor, for example, a condensate containing at least one selected from the group consisting of units of the above bisarene compounds and units of monocyclic aromatic compounds (such as hydroxyarene compounds and / or aminoarene compounds) may be used. The organic shrinkage inhibitor may at least contain a condensate containing units of bisarene compounds and units of monocyclic aromatic compounds (among others, hydroxyarene compounds). Examples of such condensates include condensates of bisarene compounds and monocyclic aromatic compounds with aldehyde compounds. As the hydroxyarene compound, a phenolsulfonic acid compound (such as phenolsulfonic acid or its substituent) is preferable. As the aminoarene compound, aminobenzenesulfonic acid, alkylaminobenzenesulfonic acid, etc. are preferable. As the monocyclic aromatic compound, a hydroxyarene compound is preferable.

[0093] 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 within 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, still more preferably 0.2% by mass or less or 0.15% by mass or less, and may be 0.12% by mass or less.

[0094] The content of the organic anti-shrinkage agent contained in the negative electrode material may be 0.005% by mass or more (or 0.01% by mass or more) and 1.0% by mass or less, 0.005% by mass or more (or 0.01% by mass or more) and 0.5% by mass or less, 0.005% by mass or more (or 0.01% by mass or more) and 0.3% by mass or less, 0.005% by mass or more (or 0.01% by mass or more) and 0.25% by mass or less, 0.005% by mass or more (or 0.01% by mass or more) and 0.2% by mass or less, 0.005% by mass or more (or 0.01% by mass or more) and 0.15% by mass or less, or 0.005% by mass or more (or 0.01% by mass or more) and 0.12% by mass or less.

[0095] (Carbonaceous material) As the carbonaceous material contained in the negative electrode material, carbon black, graphite, hard carbon, soft carbon, etc. can be used. Examples of carbon black include acetylene black, furnace black, lamp black, etc. Furnace black includes ketjen black (trade name). Graphite may be any carbonaceous material having a graphite-type crystal structure, and may be either artificial graphite or natural graphite. The negative electrode material may contain one kind of carbonaceous material or two or more kinds of carbonaceous materials.

[0096] 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.

[0097] 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.

[0098] (Barium sulfate) The content of barium sulfate 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 barium sulfate in the negative electrode material is, for example, 3% by mass or less, and may be 2% by mass or less.

[0099] The content of barium sulfate 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.

[0100] (Analysis of the negative electrode material or its components) The analysis method of the negative electrode material or its components will be described below. Prior to measurement or analysis, a fully charged lead storage battery is disassembled to obtain the 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 water washing is performed until it is confirmed that the color of the pH test paper does not change when the pH test paper is pressed against the surface of the washed negative electrode plate. However, the time for performing the water washing is within 2 hours. The washed negative electrode plate is dried at 60 ± 5°C for about 6 hours under a reduced pressure environment. When the adhered member is included in the negative electrode plate after drying, the adhered member is removed by peeling. Next, a sample (hereinafter referred to as sample A) is obtained by separating the negative electrode material from the negative electrode plate. Sample A is pulverized as necessary and used for analysis.

[0101] (1) Analysis of polymer compounds (1-1) Qualitative analysis of polymer compounds (a) Analysis of oxy C2-4 alkylene units The pulverized 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. Thereafter, the solid content is removed by filtration. For the chloroform solution in which the polymer compound obtained by extraction is dissolved or the polymer compound obtained by drying the chloroform solution to dryness, information is obtained from at least one selected from, for example, infrared spectroscopy, ultraviolet-visible absorption spectroscopy, NMR spectroscopy, LC-MS, and pyrolysis GC-MS to identify the polymer compound.

[0102] From the chloroform solution in which the polymer compound obtained by extraction is dissolved, the chloroform-soluble component is recovered by distilling off the chloroform under reduced pressure. The chloroform-soluble component is dissolved in deuterated chloroform and 1 an 1H-NMR spectrum is measured under the following conditions. 1 From this 1H-NMR spectrum, peaks in the range where the chemical shift is 3.2 ppm or more and 3.8 ppm or less are confirmed. Also, from the peaks in this range, the type of oxy C 2-4 alkylene unit is specified.

[0103] Apparatus: JEOL Ltd., AL400 type nuclear magnetic resonance apparatus 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 °C) Reference: 7.24 ppm Sample tube diameter: 5 mm

[0104] 1 From the 1H-NMR spectrum, the integration value (V1) of the peaks present in the range where the chemical shift is 3.2 ppm or more and 3.8 ppm or less is determined. Also, for each of the hydrogen atoms of the -CH2- group and -CH< group bonded to the oxygen atom bonded to the end group of the polymer compound, 1 the total integration value (V2) of the peaks in the 1H-NMR spectrum is determined. Then, from V1 and V2, the ratio that V1 occupies in the total of V1 and V2 (= V1 / (V1 + V2) × 100 (%)) is determined.

[0105] In qualitative analysis, 1 when determining the integration value of the peaks in the 1H-NMR spectrum, 1In the 1H-NMR spectrum, two points where there are no significant signals sandwiching the corresponding peak are determined, and the integral values are calculated using the straight line connecting these two points as the baseline. For example, for the peak existing in the range of chemical shift from 3.2 ppm to 3.8 ppm, the straight line connecting the two points at 3.2 ppm and 3.8 ppm in the spectrum is used as the baseline. For example, for the peak existing in the range where the chemical shift exceeds 3.8 ppm and is 4.0 ppm or less, the straight line connecting the two points at 3.8 ppm and 4.0 ppm in the spectrum is used as the baseline.

[0106] (b) Analysis of the hydrophobic group in the esterified product When the polymer compound is an esterified product of a hydroxy compound, in the above (a), a predetermined amount of the polymer compound obtained by drying the chloroform solution in which the polymer compound obtained by extraction is dissolved is collected, and an aqueous potassium hydroxide solution is added. As a result, the esterified product is saponified to produce potassium fatty acid salt and a hydroxy compound. The above-mentioned water-soluble potassium aqueous solution is added until saponification is complete. By adding a solution of methanol and boron trifluoride to the resulting mixture and mixing, the potassium fatty acid salt is converted into fatty acid methyl ester. The resulting mixture is analyzed under the following conditions by pyrolysis GC-MS to identify the hydrophobic group contained in the esterified product. Analyzer: High-performance general-purpose gas chromatogram GC-2014 manufactured by Shimadzu Corporation Column: DEGS (diethylene glycol succinate) 2.1 m Oven temperature: 180 - 120 °C Inlet temperature: 240 °C Detector temperature: 240 °C Carrier gas: He (flow rate: 50 mL / min) Injection volume: 1 μL - 2 μL

[0107] (c) Analysis of the hydrophobic group in the etherified product When the polymer compound is an etherified product of a hydroxy compound, a predetermined amount of the polymer compound obtained by drying the chloroform solution in which the polymer compound obtained by extraction is dissolved in (a) is collected and hydrogen iodide is added. This converts the organic group (the above-mentioned R 3 ) corresponding to the iodide (R 3 I) is generated and oxy C 2-4 Diiodo C corresponding to the alkylene unit 2-4 Alkanes are produced. The hydrogen iodide is converted to etherified iodide and diiodo C. 2-4 Add a sufficient amount of ether to complete the conversion to an alkane. The resulting mixture is analyzed by pyrolysis GC-MS under the same conditions as in (b) above to identify the hydrophobic group contained in the etherified product.

[0108] (1-2) Quantitative analysis of polymer compounds The appropriate amount of the chloroform soluble matter was measured with an accuracy of ±0.0001 g. r (g) Dissolve in deuterated chloroform together with tetrachloroethane (TCE), 1 Measure the H-NMR spectrum. The integral value (S a ) and the integral value of the peak due to TCE (S r ) and calculate the mass-based content C of the polymer compound in the negative electrode material from the following formula: n Calculate the ppm.

[0109] C n =S a / S r ×N r / N a ×M a / M r ×m r / m×1000000 (In the formula, M a The molecular weight of the structure that shows a peak in the chemical shift range of 3.2 to 3.8 ppm (more specifically, oxy C 2-4 (the molecular weight of the repeating structure of alkylene units) and N ais the number of hydrogen atoms bonded to the carbon atoms of the main chain of the repeating structure. N r、 M r are the number of hydrogens and the molecular weight of the reference substance contained in the molecule of the reference substance, respectively, and m (g) is the mass of the negative electrode material used for extraction.) Since the reference substance in this analysis is TCE, N r = 2, M r = 168. Also, m = 100.

[0110] For example, when the polymer compound is polypropylene glycol, M a is 58, and N a is 3. When the polymer compound is polyethylene glycol, M a is 44, and N a is 4. In the case of a copolymer, N a and M a are values obtained by averaging the N a values and M a values of each monomer unit using the molar ratio (mol%) of each monomer unit contained in the repeating structure.

[0111] In quantitative analysis, 1 the integral value of the peak in the 1H-NMR spectrum is determined using the data processing software "ALICE" manufactured by JEOL Ltd.

[0112] (1-3) Measurement of Mn of polymer compound Using the above chloroform-soluble component, GPC measurement of the polymer compound is carried out using the following apparatus under the following conditions. Separately, a calibration curve (calibration curve) is created from the plot of Mn of the reference substance and the elution time. Based on this calibration curve and the GPC measurement results of the polymer compound, Mn of the polymer compound is calculated. However, esterified products or etherified products may be in a decomposed state in the chloroform-soluble component.

[0113] Analysis system: 20A system (manufactured by Shimadzu Corporation) Column: Two GPC KF-805L (manufactured by Shodex) connected in series Column temperature: 30°C ± 1°C Mobile phase: Tetrahydrofuran Flow rate: 1 mL / min. Concentration: 0.20 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 (manufactured by Shodex, Shodex RI-201H)

[0114] (2) Analysis of the organic shrinkage inhibitor (2-1) Qualitative analysis of the organic shrinkage inhibitor in the negative electrode material The pulverized sample A is immersed in a 1 mol / L aqueous sodium hydroxide solution to extract the organic shrinkage inhibitor. Next, the insoluble components are removed from the extract by filtration, and the resulting solution is desalted, concentrated, and dried after that. Desalting is performed using a desalting column, by passing the solution through an ion exchange membrane, or by placing the solution in a dialysis tube and immersing it in distilled water. By drying this, a powder sample of the organic shrinkage inhibitor (hereinafter referred to as sample B) is obtained.

[0115] The infrared absorption spectrum measured using the sample B of the organic shrinkage inhibitor thus obtained, the ultraviolet-visible absorption spectrum measured with an ultraviolet-visible spectrophotometer after diluting sample B with distilled water or the like, the NMR spectrum of the solution obtained by dissolving sample B in a predetermined solvent such as heavy water, or information obtained from thermal decomposition GC-MS or the like that can obtain information on the individual compounds constituting the substance are combined to identify the type of the organic shrinkage inhibitor.

[0116] (2-2) Quantification of the content of the organic shrinkage inhibitor in the negative electrode material In the same manner as in (2-1) above, solutions are obtained for each of the separated substances containing the organic shrinkage inhibitor after removing the insoluble components by filtration. For each of the obtained solutions, ultraviolet-visible absorption spectra are measured. Using the intensity of the characteristic peak for each organic shrinkage inhibitor and the calibration curve prepared in advance, the content of each organic shrinkage inhibitor in the negative electrode material is determined.

[0117] When obtaining a lead-acid battery with an unknown content of the organic anti-shrinkage agent and measuring the content of the organic anti-shrinkage agent, since the exact structure of the organic anti-shrinkage agent cannot be specified, the same organic anti-shrinkage agent may not be used for the calibration curve. In this case, by creating a calibration curve using an organic anti-shrinkage agent extracted from the negative electrode of the battery and an organic polymer that is separately available and shows a similar shape in ultraviolet-visible absorption spectra, infrared spectra, and NMR spectra, etc., the content of the organic anti-shrinkage agent is measured using the ultraviolet-visible absorption spectrum.

[0118] (2-3) Content of sulfur element in the organic anti-shrinkage agent Similar to the above (2-1), after obtaining sample B of the organic anti-shrinkage agent, the sulfur element in 0.1 g of the organic anti-shrinkage agent is converted to sulfuric acid by the oxygen combustion flask method. At this time, by burning sample B in a flask containing the adsorption liquid, an eluate in which sulfate ions have dissolved in the adsorption liquid is obtained. Next, using thorin as an indicator, the content (c1) of the sulfur element in 0.1 g of the organic anti-shrinkage agent is determined by titrating the eluate with barium perchlorate. Next, c1 is multiplied by 10 to calculate the content (μmol / g) of the sulfur element in the organic anti-shrinkage agent per gram.

[0119] (Others) The negative electrode plate can be formed by applying or filling a negative electrode paste onto a negative electrode current collector, aging and drying to produce an unformed negative electrode plate, and then subjecting the unformed negative electrode plate to formation. The negative electrode paste is produced, for example, by adding water and sulfuric acid (or an aqueous sulfuric acid solution) to lead powder, a polymer compound, and at least one selected from the group consisting of an organic anti-shrinkage agent, 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 high humidity.

[0120] Formation can be carried out by charging a group of electrode plates including an unformed negative electrode plate in a state where the group of electrode plates is immersed in an electrolyte containing sulfuric acid in the battery case of the lead-acid battery. However, formation may also be carried out before assembling the lead-acid battery or the group of electrode plates. Spongy lead is generated by formation.

[0121] (Positive electrode plate) The positive electrode plate of a lead-acid battery can be classified into a paste type, a clad type, etc. 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 active material. The configuration of the clad type positive electrode plate is as described above.

[0122] The positive electrode current collector may be formed by casting lead (Pb) or a lead alloy, or may be formed by processing a lead sheet or a lead alloy sheet. Examples of the processing method include expansion processing and punching processing. It is preferable to use a grid-like current collector as the positive electrode current collector because it is easy to carry the positive electrode active material.

[0123] As the lead alloy used for the positive electrode current collector, a Pb-Sb based alloy, a Pb-Ca based alloy, or a Pb-Ca-Sn based alloy is preferable in terms of corrosion resistance and mechanical strength. The positive electrode current collector may have a surface layer. The composition of the surface layer and the inner layer of the positive electrode current collector may be different. The surface layer may be formed on a part of the positive electrode current collector. The surface layer may be formed only on the grid portion, only on the ear portion, or only on the frame portion of the positive electrode current collector. In order to enhance the adhesion between the positive electrode active material and the positive electrode current collector and suppress the positive electrode active material from peeling off from the positive electrode current collector and falling off from the positive electrode plate, the surface of the positive electrode current collector is roughened so that its arithmetic mean roughness Ra is 2 μm or more. In the case of an expanded grid or a punched current collector, for example, by pressing a plate having fine uneven portions on the surface of the lead or lead alloy sheet before processing or the current collector after processing, or by blasting the surface of the current collector, roughening can be performed. In this case, roughening may be performed on the sheet-like current collector before processing, or may be performed during or after the current collector processing. In the case of a cast current collector, roughening can be efficiently performed by providing fine unevenness on the surface of the mold used for casting.

[0124] The positive electrode active material included in the positive electrode plate contains a positive electrode active substance (lead dioxide or lead sulfate) that exhibits capacitance by an oxidation-reduction reaction. The positive electrode active material may contain other additives as required.

[0125] The unformed paste-type positive electrode plate is obtained by filling a positive electrode current collector with a positive electrode paste and subjecting it to aging and drying. The positive electrode paste is prepared by kneading lead powder, additives, water, and sulfuric acid. The unformed clad-type positive electrode plate is formed by filling a porous tube into which a spine connected at the current collecting part is inserted with lead powder or slurry-like lead powder, and joining a plurality of tubes with a spine protector. Thereafter, a positive electrode plate is obtained by forming these unformed positive electrode plates.

[0126] Forming can be carried out by charging a group of electrode plates including an unformed positive electrode plate in a state where the group of electrode plates is immersed in an electrolytic solution containing sulfuric acid in the battery case of a lead storage battery. However, forming may be carried out before assembling the lead storage battery or the group of electrode plates.

[0127] (Separator) A separator can be disposed between the negative electrode plate and the positive electrode plate. As the separator, at least one selected from nonwoven fabric and microporous membrane is used.

[0128] The nonwoven fabric is a mat in which fibers are entangled without being woven, and is mainly composed of fibers. For example, 60% by mass or more of the nonwoven fabric is formed of fibers. As the fibers, glass fibers, polymer fibers (such as polyolefin fibers, acrylic fibers, polyester fibers (such as polyethylene terephthalate fibers)), pulp fibers, etc. can be used. Among them, glass fibers are preferred. The nonwoven fabric may contain components other than fibers, such as acid-resistant inorganic powder, polymers as binders, etc.

[0129] On the one hand, the microporous membrane is a porous sheet mainly composed of components other than the fiber component. For example, it can be obtained by extruding a composition containing a pore-forming agent into a sheet shape and then removing the pore-forming agent to form pores. The microporous membrane is preferably composed of a material having acid resistance, and a microporous membrane mainly composed of a polymer component is preferred. As the polymer component, polyolefin (such as polyethylene, polypropylene, etc.) is preferred. Examples of the pore-forming agent include at least one selected from the group consisting of polymer powder and oil.

[0130] The separator may be composed of, for example, only a non-woven fabric or only a microporous membrane. Further, the separator may be, if necessary, a laminate of a non-woven fabric and a microporous membrane, a bonded product of different or the same kind of materials, or a product in which unevenness of different or the same kind of materials is engaged.

[0131] The separator may be in the form of a sheet or may be formed into a bag shape. One sheet-like separator may be disposed so as to sandwich between the positive electrode plate and the negative electrode plate. Also, one sheet-like separator in a bent state may be disposed so as to sandwich the electrode plates. In this case, the positive electrode plate sandwiched by the bent sheet-like separator and the negative electrode plate sandwiched by the bent sheet-like separator may be overlapped, or one of the positive electrode plate and the negative electrode plate may be sandwiched by the bent sheet-like separator and overlapped with the other electrode plate. Further, the sheet-like separator may be bent into a bellows shape, and the positive electrode plate and the negative electrode plate may be sandwiched between the bellows-shaped separators so that the separator is interposed therebetween. When using a separator bent into a bellows shape, the separator may be disposed such that the bent portion extends along the horizontal direction of the lead storage battery (for example, such that the bent portion is parallel to the horizontal direction), or may be disposed such that the bent portion extends along the vertical direction (for example, such that the bent portion is parallel to the vertical direction). In the separator bent into a bellows shape, concave portions are alternately formed on both main surface sides of the separator. Since ears are usually formed on the upper portions of the positive electrode plate and the negative electrode plate, when the separator is disposed such that the bent portion extends along the horizontal direction of the lead storage battery, the positive electrode plate and the negative electrode plate are disposed only in the concave portion on one main surface side of the separator (that is, a double separator is interposed between the adjacent positive electrode plate and the negative electrode plate). When the separator is disposed such that the bent portion extends along the vertical direction of the lead storage battery, the positive electrode plate can be accommodated in the concave portion on one main surface side, and the negative electrode plate can be accommodated in the concave portion on the other main surface side (that is, a single separator can be interposed between the adjacent positive electrode plate and the negative electrode plate). When using a bag-shaped separator, the bag-shaped separator may accommodate the positive electrode plate or may accommodate the negative electrode plate.

[0132] (Electrolyte solution) The electrolyte solution is an aqueous solution containing sulfuric acid and may be gelled as necessary. The above polymer compound may be contained in the electrolyte solution.

[0133] The electrolyte may contain cations (e.g., metal cations) and / or anions (e.g., anions other than sulfate anions such as phosphate ions) as required. Examples of the metal cations include at least one selected from the group consisting of Na ions, Li ions, Mg ions, and Al ions.

[0134] 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 preferably 1.35 or less, and 1.32 or less.

[0135] 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.

[0136] (Others) The lead-acid battery can be obtained by a manufacturing method including a step of accommodating 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 accommodated in each cell chamber. The plate group is assembled by laminating 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 being accommodated in the cell chamber. The positive electrode plate, the negative electrode plate, the electrolyte, and the separator are each prepared prior to the assembly of the plate group. The manufacturing method of the lead-acid battery may include a step of forming at least one of the positive electrode plate and the negative electrode plate as required after the step of accommodating the plate group and the electrolyte in the cell chamber.

[0137] Each electrode plate in the electrode plate group may be one or two or more. When the electrode plate group includes two or more positive electrode plates and two or more negative electrode plates, in at least one positive electrode plate, the arithmetic mean roughness Ra of the surface of the positive electrode current collector is 2 μm or more, and in at least one negative electrode plate, if the condition that the negative electrode active material contains the above polymer compound at a content of 600 mass ppm or less is satisfied, gas generation in the cell having this electrode plate group is suppressed, and the effect of suppressing moss short circuit is obtained. Moreover, according to the number of such negative electrode plates and positive electrode plates, the suppressing effect of moss short circuit is enhanced. From the viewpoint of further suppressing gas generation and ensuring a high suppressing effect of moss short circuit, in 50% or more (more preferably 80% or more or 90% or more) of the number of positive electrode plates included in the electrode plate group, the arithmetic mean roughness Ra of the surface of the positive electrode current collector is 2 μm or more, and in 50% or more (more preferably 80% or more or 90% or more) of the number of negative electrode plates included in the electrode plate group, it is preferable that the negative electrode active material contains the polymer compound at the above content. Among the positive electrode plates included in the electrode plate group, the ratio of the positive electrode plates satisfying the above conditions is 100% or less. Among the negative electrode plates included in the electrode plate group, the ratio of the negative electrode plates satisfying the above conditions is 100% or less. All of the positive electrode plates and negative electrode plates included in the electrode plate group may satisfy the above conditions.

[0138] When the lead storage battery has two or more cells, it is sufficient that at least a part of the electrode plate groups of the cells include positive electrode plates and negative electrode plates satisfying the above conditions. From the viewpoint of further suppressing gas generation and ensuring a high suppressing effect of moss short circuit, it is preferable that 50% or more (more preferably 80% or more or 90% or more) of the number of cells included in the lead storage battery include electrode plate groups including positive electrode plates and negative electrode plates satisfying the above conditions. Among the cells included in the lead storage battery, the ratio of the cells including electrode plate groups including positive electrode plates and negative electrode plates satisfying the above conditions is 100% or less. It is preferable that all of the electrode plate groups included in the lead storage battery include negative electrode plates satisfying the above conditions.

[0139] Fig. 1 shows the appearance of an example of a lead storage battery according to an embodiment of the present invention. The lead-acid battery 1 includes a battery case 12 that houses a plate group 11 and an electrolyte (not shown). Inside the battery case 12, a plurality of cell chambers 14 are partitioned by a partition wall 13. One plate group 11 is housed in each cell chamber 14. The opening of the battery case 12 is closed by a lid 15 having a negative terminal 16 and a positive terminal 17. The lid 15 is provided with a liquid port plug 18 for each cell chamber. When replenishing water, the liquid port plug 18 is removed and replenishing liquid is supplied. The liquid port plug 18 may have a function of discharging the gas generated in the cell chamber 14 to the outside of the battery.

[0140] The plate group 11 is configured by laminating a plurality of negative plates 2 and positive plates 3 via separators 4 respectively. Here, a bag-shaped separator 4 for housing the negative plates 2 is shown, but the form of the separator is not particularly limited. In the cell chamber 14 located at one end of the battery case 12, a negative plate rack portion 6 for connecting a plurality of negative plates 2 in parallel is connected to a through-connection body 8, and a positive plate rack portion 5 for connecting a plurality of positive plates 3 in parallel is connected to a positive electrode post 7. The positive electrode post 7 is connected to the positive terminal 17 outside the lid 15. In the cell chamber 14 located at the other end of the battery case 12, a negative electrode post 9 is connected to the negative plate rack portion 6, and a through-connection body 8 is connected to the positive plate rack portion 5. The negative electrode post 9 is connected to the negative terminal 16 outside the lid 15. Each through-connection body 8 passes through a through-hole provided in the partition wall 13 and connects the plate groups 11 in adjacent cell chambers 14 in series.

[0141] The positive plate rack portion 5 is formed by welding the ears provided on the upper portions of the respective positive plates 3 to each other by a cast-on-strap method or a burning method. The negative plate rack portion 6 is also formed by welding the ears provided on the upper portions of the respective negative plates 2 to each other in accordance with the case of the positive plate rack portion 5.

[0142] Note that the lid 15 of the lead-acid battery has a single structure (single lid), but is not limited to the illustrated example. The lid 15 may have, for example, a double structure including an inner lid and an outer lid (or an upper lid). The lid having a double structure may be provided with a reflux structure for returning the electrolyte from a reflux port provided in the inner lid to the inside of the battery (inside the inner lid) between the inner lid and the outer lid.

[0143] In this specification, the deep discharge cycle life is evaluated by the following procedure. The rated voltage of the test battery used for the evaluation is 2 V / cell, and the rated 20-hour rate capacity is 60 Ah.

[0144] (a) Deep discharge cycle life Using the test battery, perform the following under the following conditions. According to the Endurance in cycle test with 50% depth of discharge at 40℃ and preceded deep discharge test specified in EN 50432-6:2015, in a water bath at 40℃ ± 2℃, repeat the following Discharge 1 and Charge 1. In the water bath, repeat the following Discharge 1 and Charge 1.

[0145] (Discharge 1) Use a current (A) that is 0.05 times the value described for the rated capacity (the value in Ah) as the 20-hour rate current I. 20 I 20 Perform a constant current discharge at 5 times I for 2 hours. (Charge 1) Limit the charging current to 5 times or less of I, and charge at a voltage of 2.6 V / cell for 5 hours. However, end the charging when the amount of charged electricity reaches 0.54 times the rated 20-hour capacity. If the amount of charged electricity does not reach 0.54 times the rated 20-hour capacity even after 5 hours of charging, perform a constant current charge at I for up to 1 hour until the amount of charged electricity reaches 0.54 times the rated 20-hour capacity. 20 When the voltage after Charge 1 becomes 1.67 V / cell or less, end the test. The number of repetitions of Discharge 1 and Charge 1 up to this point is defined as the number of deep discharge cycles, and the deep discharge cycle life is evaluated based on this number of cycles. 20 When the voltage after Charge 1 becomes 1.67 V / cell or less, end the test. The number of repetitions of Discharge 1 and Charge 1 up to this point is defined as the number of deep discharge cycles, and the deep discharge cycle life is evaluated based on this number of cycles.

[0146] When the voltage after Charge 1 becomes 1.67 V / cell or less, end the test. The number of repetitions of Discharge 1 and Charge 1 up to this point is defined as the number of deep discharge cycles, and the deep discharge cycle life is evaluated based on this number of cycles.

[0147] The lead-acid battery according to one aspect of the present invention is summarized as follows.

[0148] (1) A lead-acid battery, The lead-acid battery includes a negative electrode plate, a positive electrode plate, and an electrolytic solution. The negative electrode plate comprises a negative electrode material, The positive electrode plate includes a positive electrode current collector and a positive electrode material, The negative electrode material is measured using deuterated chloroform as a solvent. 1 The polymer compound has a peak in the range of 3.2 ppm to 3.8 ppm in the chemical shift of H-NMR spectrum, The content of the polymer compound in the negative electrode material is 600 ppm or less by mass, The positive electrode current collector has a surface having an arithmetic mean roughness Ra of 2 μm or more.

[0149] (2) In the above (1), the polymer compound contains an oxygen atom bonded to an end group and a -CH- group and / or a -CH< group bonded to the oxygen atom, The above 1 In the H-NMR spectrum, the ratio of the integral value of the peak to the sum of the integral value of the peak, the integral value of the peak due to the hydrogen atom of the -CH- group, and the integral value of the peak due to the hydrogen atom of the -CH< group may be 50% or more, 80% or more, 85% or more, or 90% or more.

[0150] (3) In the above (1) or (2), the polymer compound is oxyC 2-4 It may contain a repeating structure of alkylene units.

[0151] (4) A lead-acid battery, The lead-acid battery includes a negative electrode plate, a positive electrode plate, and an electrolyte, The negative electrode plate comprises a negative electrode material, The positive electrode plate includes a positive electrode current collector and a positive electrode material, The negative electrode material is oxyC 2-4 The polymer compound includes a repeating structure of an alkylene unit, The content of the polymer compound in the negative electrode material is 600 ppm or less by mass, The positive electrode current collector has a surface having an arithmetic mean roughness Ra of 2 μm or more.

[0152] (5) In any one of the above (1) to (4), the content of the polymer compound in the negative electrode material may be 30 ppm or more and 500 ppm or less on a mass basis.

[0153] (6) In any one of the above (1) to (5), the arithmetic mean roughness Ra of the surface of the positive electrode current collector may be 50 μm or less or 10 μm or less.

[0154] (7) In any one of the above (1) to (6), the arithmetic mean roughness Ra of the surface of the positive electrode current collector may be 4 μm or more.

[0155] (8) In any one of the above (1) to (7), the polymer compound may contain a compound in which Mn is 5 million or less, 3 million or less, 2 million or less, 500,000 or less, 100,000 or less, 50,000 or less, 20,000 or less, 10,000 or less, 5,000 or less, 4,000 or less, 3,000 or less, or 2,500 or less.

[0156] (9) In any one of the above (1) to (8), the polymer compound may contain a compound in which Mn is 300 or more, 400 or more, 500 or more, 1,000 or more, 1,500 or more, or 1,800 or more.

[0157] (10) In any one of the above (1) to (9), the polymer compound contains at least one selected from the group consisting of a hydroxy compound having a repeating structure of the oxy C 2-4 alkylene unit, an etherified product of the hydroxy compound, and an esterified product of the hydroxy compound, the hydroxy compound is poly C 2-4 alkylene glycol, oxy C 2-4 a copolymer containing a repeating structure of alkylene, and a poly C 2-4 alkylene oxide adduct of a polyol, and may be at least one selected from the group consisting of them.

[0158] (11) In (10) above, the polymer compound may contain at least one selected from the group consisting of polyethylene glycol oleate, polyethylene glycol dilaurate, polyethylene glycol distearate, and polyethylene glycol dioleate.

[0159] [Examples] Hereinafter, the present invention will be specifically described based on examples and comparative examples, but the present invention is not limited to the following examples.

[0160] 《Lead-acid batteries A1 to A20》 (1) Preparation of lead-acid batteries (a) Preparation of negative electrode plates Powdered lead as a raw material, barium sulfate, carbon black, polyethylene glycol oleate (Mn500) as a polymer compound, and sodium lignosulfonate as an organic anti-shrinkage agent are mixed with an appropriate amount of sulfuric acid aqueous solution to obtain a negative electrode paste. At this time, the content of the polymer compound in the negative electrode material, which is required by the above-mentioned procedure in each case, becomes the value shown in Table 1, and the components are mixed so that the content of the organic anti-shrinkage agent is 0.1% by mass, the content of barium sulfate is 0.4% by mass, and the content of carbon black is 0.2% by mass. The negative electrode paste is filled into the mesh portion of an expanded grid made of Pb-Ca-Sn alloy, aged and dried to obtain an unformed negative electrode plate.

[0161] (b) Preparation of positive electrode plates Powdered lead as a raw material is mixed with a sulfuric acid aqueous solution to obtain a positive electrode paste. A punched current collector made of Pb-Ca-Sn alloy is prepared, and the surfaces of the vertical and horizontal ribs of the current collector are pressed against a predetermined mold to obtain a positive electrode current collector having an arithmetic mean surface roughness Ra shown in Table 1 on the surface of the positive electrode current collector. The positive electrode paste is filled into the mesh portion of the positive electrode current collector, aged and dried to obtain an unformed positive electrode plate.

[0162] (c) Preparation of test batteries The rated voltage of the test battery is 2 V / cell, and the rated 20-hour rate capacity is 60 Ah. The electrode plate group of the test battery is composed of 7 positive electrode plates and 7 negative electrode plates. The negative electrode plates are housed in a bag-shaped separator formed of a microporous membrane made of polyethylene, and are alternately laminated with the positive electrode plates to form an electrode plate group. The electrode plate group is housed in a battery case made of polypropylene together with an electrolytic solution (aqueous sulfuric acid solution), and formation is performed in the battery case to produce a flooded lead-acid battery. The specific gravity of the electrolytic solution in the fully charged lead-acid battery at 20 °C is 1.28.

[0163] When the polymer compound has a repeating structure of oxyethylene units, the 1 1H-NMR spectrum of the polymer compound measured by the above-described procedure shows a peak derived from -CH2- of the oxyethylene unit in the chemical shift range of 3.2 ppm or more and 3.8 ppm or less. When the polymer compound has a repeating structure of oxypropylene units, the 1 1H-NMR spectrum of the polymer compound measured by the above-described procedure shows a peak derived from -CH2- of the oxypropylene unit in the chemical shift range of 3.2 ppm or more and 3.42 ppm or less, and peaks derived from -CH and -CH2- of the oxypropylene unit in the chemical shift range of more than 3.42 ppm and 3.8 ppm or less. Also, 1 in the 1H-NMR spectrum, the ratio of the integral value of the peak in the range of 3.2 ppm to 3.8 ppm to the total of the integral values of the peak of the hydrogen atom of the -CH2- group bonded to the oxygen atom and the peak of the hydrogen atom of the -CH group bonded to the oxygen atom is 96 to 100%.

[0164] In this way, batteries A1 to A20 are produced in which the combination of the content of the polymer compound in the negative electrode material and / or the arithmetic mean surface roughness Ra of the surface of the positive electrode current collector is different, and are evaluated as described below. Note that batteries A2 to A4, A6 to A8, A10 to A12, and A14 to A16 are examples, and batteries A1, A5, A9, A13, and A17 to A20 are comparative examples.

[0165] "Lead-acid Batteries B1 - B4" In the production of the negative electrode plate, as the polymer compound, instead of polyethylene glycol oleate, any one of polyethylene glycol dilaurate (Mn630), polyethylene glycol distearate (Mn810), polyethylene glycol dioleate (Mn880), or polypropylene glycol is used to obtain a negative electrode paste. The polymer compound is mixed into the negative electrode paste so that the content of the polymer compound in the negative electrode material is 0.0265% by mass (265 ppm). In the same manner as for batteries A1 - A20, a negative electrode plate is produced and a test battery is produced. In this way, batteries B1 - B4 (Examples) with different polymer compounds in the negative electrode material are produced and evaluated as described below.

[0166] "Lead-acid Batteries C1 - C4" In the production of the negative electrode plate, a negative electrode paste without adding a polymer compound is obtained. In the same manner as for batteries A1 - A20, a negative electrode plate is produced and a test battery is produced. In this way, batteries C1 - C4 (Comparative Examples) that do not contain a polymer compound in the negative electrode material and have different surface roughness Ra values of the positive electrode current collector are produced and evaluated as described below.

[0167] (2) Evaluation (a) Deep discharge cycle life Using the above test battery, the number of deep discharge cycles is measured by the procedure described above. The number of deep discharge cycles of each lead-acid battery is evaluated at a ratio when the number of deep discharge cycles of lead-acid battery C1 is set to 100.

[0168] The results are shown in Table 1. As shown in Table 1, in batteries A2 - A4, A6 - A8, A10 - A12, A14 - A16, and B1 - B4 where a polymer compound is added to the negative electrode material at a content of 600 ppm (0.06% by mass) or less on a mass basis and the surface roughness Ra of the positive electrode current collector is 2 μm or more, compared with battery C1 where no polymer compound is added and the surface roughness Ra of the positive electrode current collector is less than 2 μm, the number of deep discharge cycles is greatly improved.

[0169] From Table 1, the number of deep discharge cycles tends to increase as the surface roughness Ra of the positive current collector increases. Also, the number of deep discharge cycles increases rapidly when the surface roughness Ra of the positive current collector is around 2 μm, and the increasing range decreases and approaches a constant value in the range of 2 μm to 4 μm. However, when comparing batteries A1 - A20 with batteries C1 - C4 without the addition of the polymer compound, when the polymer compound is added at a content of 600 ppm (0.06% by mass) or less, the number of deep discharge cycles increases significantly with the increase in Ra.

[0170] From Table 1, when no polymer compound is added, in batteries C2 - C4 where the surface roughness Ra of the positive current collector is 2 μm or more, the number of deep discharge cycles is improved by about 7% compared to battery C1 where the surface roughness Ra is less than 2 μm. Also, when the polymer compound is added at a content of 600 ppm (0.06% by mass) or less and the surface roughness Ra of the positive current collector is less than 2 μm, for example, in batteries A5 and A9, the improvement in the number of deep discharge cycles is about 7% compared to battery C1.

[0171] On the other hand, when the polymer compound is added at a content of 600 ppm (0.06% by mass) or less and the surface roughness Ra of the positive current collector is 2 μm or more, for example, in batteries A6 - A8, A11 - 12, an improvement in the number of deep discharge cycles of about 40% is observed compared to battery C1, and the number of deep discharge cycles is improved more than expected.

[0172]

Table 1

[0173] Figure 2A is a graph plotting the change in the number of deep discharge cycles when the content of the polymer compound is varied for batteries A1 to A20 and batteries C1 to C4. Figure 2B is a graph plotting the change in the number of deep discharge cycles when the surface roughness Ra of the positive electrode current collector is varied for batteries A1 to A16 and batteries C1 to C4. As shown in Figure 2A, when the surface roughness Ra of the positive electrode current collector is 2 μm or more, the number of deep discharge cycles increases rapidly with the content of the polymer compound around 30 ppm on a mass basis as the boundary. In particular, in the range where the content of the polymer compound is 30 ppm to 500 ppm on a mass basis, the increase in the number of deep discharge cycles is remarkable. Further, as shown in Figure 2B, when the content of the polymer compound is 600 ppm or less on a mass basis, the surface roughness Ra of the positive electrode current collector is 2 μm or more, and the number of deep discharge cycles increases rapidly.

Industrial Applicability

[0174] The lead-acid batteries according to one aspect and other aspects of the present invention are suitable for use in an idling stop vehicle as an IS lead-acid battery that is charged and discharged under, for example, PSOC conditions. Further, the lead-acid battery can be preferably used as, for example, a starting power source for a vehicle (automobile, motorcycle, etc.) or an industrial power storage device (for example, a power source for an electric vehicle (forklift, etc.)). Note that these are merely examples, and the uses of the lead-acid battery are not limited thereto.

Explanation of Signs

[0175] 1: Lead-acid battery 2: Negative electrode plate 3: Positive electrode plate 4: Separator 5: Positive electrode grid part 6: Negative electrode grid part 7: Positive electrode post 8: Through connection body 9: Negative electrode post 11: Electrode plate group 12: Battery case 13: Partition wall 14: Cell chamber 15: Cover 16: Negative electrode terminal 17: Positive electrode terminal 18: Liquid stopper

Claims

1. A lead-acid battery, comprising a negative electrode plate, a positive electrode plate, and an electrolyte, the negative electrode plate comprising a negative electrode material, the positive electrode plate comprising a positive electrode current collector and a positive electrode material, the negative electrode material containing a polymer compound having a peak in the range of 3.2 ppm or more and 3.8 ppm or less in the chemical shift of the H-NMR spectrum measured using deuterated chloroform as a solvent, １ and the content of the polymer compound in the negative electrode material being 600 ppm or less on a mass basis, and the arithmetic mean roughness Ra of the surface of the positive electrode current collector being 2 μm or more. A lead-acid battery.

2. The polymer compound contains an oxygen atom bonded to a terminal group, and a -CH - group and / or a -CH< group bonded to the oxygen atom, ２ and in the H-NMR spectrum, the ratio of the integral value of the peak to the sum of the integral values of the peaks of the hydrogen atoms of the -CH - group and the integral value of the peak of the hydrogen atoms of the -CH< group is 85% or more. The lead-acid battery according to Claim 1. １ - group and the integral value of the peak of the hydrogen atoms of the -CH< group is 85% or more. The lead-acid battery according to Claim 1. ２ - group and the integral value of the peak of the hydrogen atoms of the -CH< group is 85% or more. The lead-acid battery according to Claim 1.

3. The polymer compound contains a repeating structure of an oxyC ２－４ alkylene unit. The lead-acid battery according to Claim 1 or 2.

4. A lead-acid battery, comprising a negative electrode plate, a positive electrode plate, and an electrolyte, the negative electrode plate comprising a negative electrode material, the positive electrode plate comprising a positive electrode current collector and a positive electrode material, the negative electrode material containing a polymer compound containing a repeating structure of an oxyC ２－４ alkylene unit, The content of the polymer compound in the negative electrode material is 600 ppm or less on a mass basis. A lead storage battery in which the arithmetic mean roughness Ra of the surface of the positive electrode current collector is 2 μm or more.

5. The lead storage battery according to any one of claims 1 to 4, wherein the content of the polymer compound in the negative electrode material is 30 ppm or more and 500 ppm or less on a mass basis.

6. The lead storage battery according to any one of claims 1 to 5, wherein the arithmetic mean roughness Ra of the surface of the positive electrode current collector is 50 μm or less.

7. The polymer compound contains at least one selected from the group consisting of hydroxy compounds having a repeating structure of oxy C ２－４ alkylene units, etherified products of the hydroxy compounds, and esterified products of the hydroxy compounds. The hydroxy compound is poly C ２－４ alkylene glycol, a copolymer containing a repeating structure of oxy C ２－４ alkylene, and a poly C ２－４ alkylene oxide adduct of a polyol, and is at least one selected from the group consisting thereof. The lead storage battery according to any one of claims 1 to 6.

8. The lead storage battery according to claim 7, wherein the polymer compound contains at least one selected from the group consisting of polyethylene glycol oleate, polyethylene glycol dilaurate, polyethylene glycol distearate, and polyethylene glycol dioleate.

9. The lead storage battery according to any one of claims 1 to 8, wherein the arithmetic mean roughness Ra of the surface of the positive electrode current collector is 10 μm or less.

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