lead-acid batteries

Abstract

Disclosed is a lead acid storage battery 1 which is provided with an electrode plate group 11, an electrolyte solution, and a battery case 12 that contains the electrode plate group 11 and the electrolyte solution. The electrode plate group 11 comprises a plurality of positive electrode plates 2 and a plurality of negative electrode plates 3, which are stacked upon each other. The negative electrode plates 3 contain a negative electrode material. The negative electrode material contains a polymer compound. The polymer compound has a peak within the range of from 3.2 ppm to 3.8 ppm in the chemical shift in the 1H–NMR spectrum as determined with use of deuterated chloroform that serves as a solvent. The content of the polymer compound in the negative electrode material is from 15 ppm to 400 ppm on a mass basis. The pull-out load at the time when the electrode plate group 11 is pulled out from the battery case 12 is not less than 1.5 times the weight of the electrode plate group 11 itself.

Description

[Technical Field]

[0001] The present invention relates to a lead-acid battery. [Background technology]

[0002] Lead-acid batteries are used in a variety of applications, including automotive and industrial applications. Depending on the application, at least one of high charge acceptance, small overcharge capacity, and low short-circuit occurrence rate is particularly important for lead-acid batteries.

[0003] Patent Document 1 (JP 2003-051288 A) discloses "a battery case for a lead-acid battery, which stores a plurality of electrode plate assemblies, the battery case being divided into a plurality of battery cell chambers by a partition, and in which the width of the cell chambers located at both ends in the stacking direction of the electrode plate assemblies is configured to be narrower than the width of the other cell chambers in the same direction, so that the pull-out load for all of the electrode plate assemblies after electrolyte injection is made approximately uniform." Table 1 of Patent Document 1 also lists "the pull-out load for the electrode assembly stored in the middle cell" and "the pull-out load for the electrode assembly stored in the end cells."

[0004] Patent Document 2 (JP 2009-123433 A) discloses "a method for manufacturing a valve-regulated lead-acid battery in which an electrode plate group including positive electrode plates, negative electrode plates, and a separator is placed in a battery case, the method comprising the steps of: preparing positive electrode plates using lead powder and red lead having a red lead content of 20% by mass to 80% by mass as raw positive electrode active material; and placing the electrode plate group in the battery case so that a compressive force of 9.8 to 34.3 kPa is applied to the electrode plate group."

[0005] Patent Document 3 (Japanese Patent Laid-Open Publication No. 60-182662) discloses "a lead-acid battery characterized in that a copolymer of propylene oxide and ethylene oxide is added to the negative electrode plate active material in combination with lignin sulfonate." [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-051288 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-123433 [Patent Document 3] Japanese Patent Application Publication No. 182662 / 1983 Summary of the Invention [Problem to be solved by the invention]

[0007] Currently, there is a demand for a lead-acid battery that can achieve a good balance between a small amount of overcharge electricity, a high charge acceptance performance, and a low incidence of short circuits. [Means for solving the problem]

[0008] A lead-acid battery according to one aspect of the present invention includes a plate assembly, an electrolyte, and a battery case that accommodates the plate assembly and the electrolyte, the plate assembly including a plurality of stacked positive plate plates and a plurality of stacked negative plate plates, the negative plate plates including a negative electrode material, the negative electrode material including a polymer compound, and the polymer compound is measured using deuterated chloroform as a solvent. 1 The negative electrode material 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, the content of the polymer compound in the negative electrode material is 15 ppm or more and 400 ppm or less by mass, and the pull-out load when the electrode plate group is pulled out of the battery case is 1.5 times or more the weight of the electrode plate group itself.

[0009] A lead-acid battery according to another aspect of the present invention includes a plate assembly, an electrolyte, and a battery case that accommodates the plate assembly and the electrolyte. The plate assembly includes a plurality of stacked positive plate plates and a plurality of stacked negative plate plates. The negative plate plates include a negative electrode material. The negative electrode material includes a polymer compound. The polymer compound is an oxy-C 2-4The negative electrode material contains an alkylene unit as a repeating structure, the content of the polymer compound in the negative electrode material is 15 ppm or more and 400 ppm or less by mass, and the pull-out load when the electrode plate group is pulled out of the battery case is 1.5 times or more the weight of the electrode plate group itself. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a partially cutaway exploded perspective view showing the appearance and internal structure of a lead-acid battery according to one aspect of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The following describes embodiments of the present invention using examples, but the present invention is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be used as examples, but other numerical values ​​and materials may be used as long as the effects of the present invention are obtained. In this specification, the range described as "numerical value A to numerical value B" includes numerical value A and numerical value B.

[0012] [Lead acid battery] A lead-acid battery according to one embodiment of the present invention includes a plate assembly, an electrolyte, and a battery case that houses the plate assembly and the electrolyte. The plate assembly includes a plurality of stacked positive and negative plate assembly. The negative plate assembly includes a negative electrode material. The negative electrode material includes a polymer compound. Hereinafter, the polymer compound may be referred to as a "polymer compound (P)." The content of the polymer compound (P) in the negative electrode material is 15 ppm or more and 400 ppm or less by mass. The pull-out load when pulling out the plate assembly from the battery case is 1.5 times or more the weight of the plate assembly.

[0013] The first example of the polymer compound (P) is measured using deuterated chloroform as a solvent. 1 It is a polymer compound having a peak in the range of 3.2 ppm to 3.8 ppm in the chemical shift of the H-NMR spectrum. 1Unless otherwise specified, the H-NMR spectrum is measured using deuterated chloroform as a solvent. 2-4 It is a polymer compound containing a repeating structure of alkylene units. The polymer compounds included in the first example of polymer compound (P) and the polymer compounds included in the second example of polymer compound (P) overlap at least partially. The description of polymer compound (P) is applicable to both the first example and the second example of polymer compound (P) unless otherwise specified. A commercially available polymer compound (P) may be used. Alternatively, polymer compound (P) may be synthesized by a known method.

[0014] That is, the negative electrode material for a lead acid battery according to one embodiment of the present invention contains, as the polymer compound (P), a polymer compound that satisfies the following condition (i): (i) Measured using deuterated chloroform as a solvent 1 In the chemical shift of the H-NMR spectrum, it has a peak in the range of 3.2 ppm to 3.8 ppm.

[0015] A negative electrode material for a lead acid battery according to another embodiment of the present invention contains, as the polymer compound (P), a polymer compound that satisfies the following condition (ii): (ii) OxyC 2-4 It contains alkylene units as a repeating structure.

[0016] As a result of investigations, the present inventors have newly discovered that when the negative electrode material contains the polymer compound (P) in the above content and the pull-out load of the electrode plate assembly is within the above range, a lead-acid battery with good characteristics can be obtained. Specifically, by satisfying the above conditions, a lead-acid battery can be obtained that can achieve a good balance of a small overcharge quantity of electricity, high charge acceptance, and a low incidence of permeable short circuits. The present invention is based on this new finding.

[0017] By reducing the amount of overcharge electricity, gas generation during overcharge can be suppressed, thereby suppressing the decrease in electrolyte (hereinafter sometimes referred to as "liquid loss"). As a result, this is advantageous for extending the life of lead-acid batteries. By improving charge acceptance, regeneration performance can be improved and sulfation can be prevented.

[0018] The polymer compound (P) is thought to thinly coat the surface of the negative electrode active material. Therefore, the polymer compound (P) is thought to suppress the growth of dendrites, which are caused by the deposition of lead ions dissolved from the negative electrode active material on the negative electrode active material. A high pull-out load ratio narrows the plate spacing, generally making permeation short circuits more likely to occur. However, if the negative electrode material contains an appropriate amount of polymer compound (P), dendrite growth is suppressed, thereby preventing permeation short circuits even with a narrow plate spacing. Furthermore, a high pull-out load is thought to suppress the migration of the polymer compound (P), making it more likely to remain in the negative electrode plate. As a result, a high pull-out load may be more effective in suppressing short circuits. Furthermore, a high pull-out load ratio reduces charge transfer resistance due to the narrow plate spacing, improving charge acceptance. A high concentration of polymer compound (P) tends to increase the proportion of the surface of the negative electrode active material covered by the polymer compound (P), resulting in a decrease in charge acceptance. However, when the content of the polymer compound (P) is 400 ppm or less, it is believed that the decrease in charge acceptance can be suppressed by setting the withdrawal load ratio to 1.5 or more. Furthermore, by adding the polymer compound (P) to the negative electrode material, the hydrogen overvoltage at the negative plate can be increased, thereby suppressing the overcharge quantity of electricity. As a result, the decrease in electrolyte can be suppressed. The above reasons may be the reason why the lead-acid battery of the present invention achieves a good balance between a small overcharge quantity of electricity, high charge acceptance, and a low incidence of permeation short circuits.

[0019] The peak described in the above condition (i) is oxy C 2-4The polymer compound (P) may be derived from an alkylene unit. The polymer compound (P) contains a repeating structure of a monomer unit and / or has a certain molecular weight. More specifically, the polymer compound (P) that satisfies the condition (i) is a polymer compound (P) that contains an oxy-C 2-4 It may have a repeating structure of alkylene units and / or may have a number average molecular weight (Mn) of 500 or more. The Mn of the polymer compound (P) satisfying the above condition (ii) may be 300 or more.

[0020] The value obtained by dividing the pull-out load (kgf) when pulling out the electrode plate assembly from the battery case by the weight (kgf) of the electrode plate assembly may be referred to as the "pull-out load ratio" below. The pull-out load ratio is expressed by the following formula. The pull-out load and the weight of the electrode plate assembly may be expressed in units of N (Newton). (Pull-out load ratio) = (Pull-out load when pulling out the electrode plate group from the battery case) / (Weight of the electrode plate group)

[0021] The value of the pull-out load ratio indicates how many times the pull-out load when pulling out the electrode plate group from the battery case is greater than the weight of the electrode plate group. The larger the pull-out load ratio, the more compressed the electrode plate group is inside the battery case. Normally, the larger the pull-out load ratio, the narrower the gap between adjacent electrodes.

[0022] The pull-out load when pulling out the electrode plate assembly from the battery case may be 10 times or less the weight of the electrode plate assembly. That is, the pull-out load ratio may be 10.0 or less. If the pull-out load ratio exceeds 10.0, it may be difficult to insert the electrode plate assembly into the battery case, or the separator may be torn.

[0023] As described above, the pull-out load ratio is 1.5 or greater. The pull-out load ratio may be 1.5 or greater, 1.8 or greater, 2.0 or greater, or 2.5 or greater. The pull-out load ratio may be 10.0 or less, 9.0 or less, 6.0 or less, 4.0 or less, 3.0 or less, 2.5 or less, or 2.0 or less. These lower and upper limits can be arbitrarily combined unless there is a contradiction. For example, the pull-out load ratio may be in the range of 1.5 to 10.0, 1.5 to 9.0, 1.5 to 6.0, 1.5 to 4.0, or 1.5 to 3.0. Within these ranges, the lower limit may be changed to 1.8, 2.0, or 2.5.

[0024] The lead-acid battery may include a battery case containing multiple cell chambers and multiple plate groups. Typically, one plate group is disposed in each cell chamber. In this case, it is sufficient that at least one cell chamber and the plate group disposed in that cell chamber satisfy the above conditions. It is preferable that all cell chambers and the plate groups disposed in those cell chambers satisfy the above conditions.

[0025] The polymer compound (P) is oxy-C 2-4 It is preferable that the alkylene unit contains a repeating structure. 2-4 When a polymer compound (P) containing a repeating structure of alkylene units is used, it is believed that it is more easily adsorbed to lead and that its linear structure makes it easier to thinly coat the lead surface. It is believed that the coating of the lead surface with the polymer compound (P) can suppress the occurrence of permeation short circuits. Furthermore, it is believed that the thin coating of the polymer compound (P) can suppress a significant decrease in charge acceptance performance. Therefore, in this case, a lead-acid battery with particularly good characteristics can be obtained.

[0026] The polymer compound (P) may be at least one selected from the group consisting of polyethylene glycol, esterified polyethylene glycol, polypropylene glycol, and esterified polypropylene glycol. For example, the polymer compound (P) may be polypropylene glycol. These configurations result in a lead-acid battery with particularly good characteristics.

[0027] The number average molecular weight of the polymer compound (P) may be equal to or greater than 1000. This configuration particularly reduces the amount of electricity in overcharge.

[0028] The polymer compound (P) is oxy-C 2-4 The hydroxy compound may contain at least one selected from the group consisting of a hydroxy compound containing a repeating structure of an alkylene unit, an etherified product of the hydroxy compound, and an esterified product of the hydroxy compound. 2-4 Alkylene glycol, oxy C 2-4 Copolymers containing repeating alkylene units and polyol C 2-4 The polymer compound (P) is at least one selected from the group consisting of alkylene oxide adducts. By using such a polymer compound (P), it is possible to obtain a lead-acid battery having particularly good characteristics.

[0029] Oxy C 2-4 The repeating structure of the alkylene unit may contain at least a repeating structure of an oxypropylene unit (-O-CH(-CH3)-CH2-). Such a polymer compound (P) is considered to have an excellent balance of high adsorption to lead while easily spreading thinly on the lead surface. Therefore, by using such a polymer compound (P), it is possible to obtain a lead-acid battery with particularly good characteristics.

[0030] The polymer compound (P) has high adsorption properties for lead and can thinly cover the lead surface, so that the above-mentioned effects can be obtained even if the content of the polymer compound (P) in the negative electrode material is very small (more specifically, 400 ppm or less).

[0031] The origin of the polymer compound (P) contained in the negative electrode material is not particularly limited as long as the polymer compound (P) can be contained in the negative electrode material. When producing a lead-acid battery, the polymer compound (P) may be contained in any of the components of the lead-acid battery (e.g., the negative electrode plate, the positive electrode plate, the electrolyte, and the separator). The polymer compound may be contained in one component, or in two or more components (e.g., the negative electrode plate and the electrolyte).

[0032] The pull-out load required to pull the electrode assembly from the battery case can be varied by, for example, the width W of the battery case (or cell chamber) or the thickness of the electrode assembly. Alternatively, the pull-out load can be varied by, as needed, placing spacers between the inner wall of the battery case and the electrode plates at the ends of the electrode assembly. Here, the width W of the battery case (or cell chamber) refers to the length of the space within the battery case (the space in which the electrode assembly is located) in the direction in which the positive and negative electrode plates are stacked within the battery case. The thickness of the electrode assembly may be varied by changing at least one selected from the group consisting of the amount of positive electrode material held in the positive electrode plate, the amount of negative electrode material held in the negative electrode plate, the shape of the positive electrode current collector, and the shape of the negative electrode current collector. The pull-out load ratio can be varied by varying the pull-out load. Note that the pull-out load ratio is usually approximately the same or does not differ significantly before and after chemical formation. Therefore, it is possible to fabricate batteries with a certain degree of predictability of the pull-out load ratio after chemical formation.

[0033] (Terminology explanation) The terms used in this specification are explained below.

[0034] (Weight of electrode plate group) In this specification, the dead weight of a plate assembly is a weight measured by the following procedure. First, the top cover of a fully charged lead-acid battery is cut off to disassemble the battery, and then all of the electrolyte in the battery case is drained and the plate assembly is removed. Next, the dead weight (W1) of the removed plate assembly is measured using a balance while it is soaked with electrolyte (the plates are wet). In this way, the dead weight (W1) of the plate assembly is measured. The plate assembly whose dead weight is measured includes the positive plate, the negative plate, and other components of the plate assembly (e.g., separators and straps).

[0035] (Pulling load of electrode plate group) In this specification, the electrode plate pack pull-out load is a load measured by the following procedure. First, the electrode plate pack whose weight has been measured as described above is returned to the battery case, and a hook is attached to a part of the electrode plate pack (for example, a strap portion) to pull out the electrode plate pack. At this time, a digital force gauge is used to measure the load when pulling out the electrode plate pack from the battery case. The maximum value of the measured load is defined as the electrode plate pack pull-out load (W2). The pull-out load ratio (compression force) is calculated by dividing the pull-out load (W2) by the electrode plate pack's weight (W1).

[0036] (Top and bottom directions of lead-acid batteries or components of lead-acid batteries) In this specification, the up-down direction of a lead-acid battery or components of a lead-acid battery (such as electrodes, a battery case, and a separator) refers to the up-down direction (vertical direction) of the lead-acid battery when the lead-acid battery is placed in a normal use state.

[0037] (Negative electrode material) The negative electrode material is usually held by a current collector (negative current collector). The negative electrode material is the portion of the negative electrode plate excluding the current collector. A mat, pasting paper, or other member may be attached to the negative electrode plate. Such members (also referred to as attachment members) are used integrally with the negative electrode plate and are therefore included in the negative electrode plate. When the negative electrode plate includes an attachment member (mat, pasting paper, etc.), the negative electrode material is the portion excluding the current collector and attachment member.

[0038] (polymer compound) As described above, the polymer compound (P) satisfies at least one of the following conditions (i) and (ii): (i) Measured using deuterated chloroform as a solvent 1 In the chemical shift of the H-NMR spectrum, it has a peak in the range of 3.2 ppm to 3.8 ppm. (ii) OxyC 2-4 It contains alkylene units as a repeating structure.

[0039] Under condition (i), the peak in the range of 3.2 ppm to 3.8 ppm is oxy-C. 2-4 It is derived from an alkylene unit. In other words, the polymer compound (P) satisfying the condition (ii) is also the polymer compound (P) satisfying the condition (i). The polymer compound (P) satisfying the condition (i) is a polymer compound (P) having an oxy C 2-4 The polymer compound (P) may contain a repeating structure of a monomer unit other than an alkylene unit, as long as it has a certain molecular weight. The number average molecular weight (Mn) of the polymer compound (P) satisfying the above (i) or (ii) may be, for example, 300 or more.

[0040] (Oxy C 2-4 alkylene unit) Oxy C 2-4 The alkylene unit is -OR 1 - is a unit expressed as R 1 is C 2-4 This represents an alkylene group (an alkylene group having 2 to 4 carbon atoms).

[0041] (number average molecular weight) The number average molecular weight (Mn) is determined by gel permeation chromatography (GPC). The standard substance used to determine Mn is polyethylene glycol.

[0042] (Weight average molecular weight) The weight average molecular weight (Mw) is determined by GPC. The standard substance used to determine Mw is sodium polystyrene sulfonate.

[0043] (Sulfur element content in organic shrinkage inhibitors) The content of sulfur element in the organic shrink-preventing agent being X μmol / g means that the content of sulfur element contained in 1 g of the organic shrink-preventing agent is X μmol.

[0044] (fully charged) The fully charged state of a flooded lead-acid battery is defined by JIS D 5301:2019. More specifically, a fully charged state is defined as a state in which a lead-acid battery is charged in a water tank at 25°C ± 2°C with a current (A) 0.2 times the rated capacity (unit: Ah) until the terminal voltage (V) during charging or the electrolyte density converted to 20°C temperature shows a constant value to three significant digits three times consecutively. For a valve-regulated lead-acid battery, a fully charged state is defined as a state in which a battery is charged in an air tank at 25°C ± 2°C with a constant current / constant voltage of 2.23 V / cell with a current (A) 0.2 times the rated capacity (unit: Ah), and charging is terminated when the charging current during constant voltage charging reaches a value (A) 0.005 times the rated capacity (unit: Ah).

[0045] A fully charged lead-acid battery refers to a fully charged lead-acid battery that has already been formed. A lead-acid battery can be fully charged immediately after formation, or after some time has passed since formation (for example, a lead-acid battery that has been in use (preferably in the early stages of use) after formation can be fully charged). A battery in the early stages of use refers to a battery that has not been in use for very long and has hardly deteriorated at all.

[0046] The configuration of a lead-acid battery according to one embodiment of the present invention will be specifically described below, but the present invention is not limited to the following configuration.

[0047] [Lead acid battery] The lead-acid battery may be either a valve-regulated (sealed) lead-acid battery (VRLA battery) or a flooded (vented) lead-acid battery. Examples of the main components of a lead-acid battery are described below.

[0048] (negative plate) The negative electrode plate includes a current collector (negative electrode current collector) and a negative electrode material.

[0049] (current collector) The negative electrode current collector may be formed by casting lead (Pb) or a lead alloy, or by processing a lead sheet or a lead alloy sheet. Examples of processing methods include expanding and punching. Examples of current collectors include lattice-shaped current collectors, commonly called grids, current collectors punched into circles or ellipses, and current collectors with grids radially extending from the edges of the current collector. Even non-lattice-shaped current collectors may be called grids. Using a grid-shaped current collector as the negative electrode current collector is preferable because it is easy to support the negative electrode material.

[0050] The lead alloy used for the negative electrode current collector may be either a Pb-Ca alloy or a Pb-Ca-Sn alloy, and the lead or lead alloy may further contain at least one additive element selected from the group consisting of Ba, Ag, Al, Bi, As, Se, and Cu.

[0051] (Negative electrode material) The negative electrode material includes the polymer compound (P). The negative electrode material further includes a negative electrode active material (specifically, lead or lead sulfate) that exhibits capacity through a redox reaction. The negative electrode material may include at least one selected from the group consisting of an organic shrinkage inhibitor, a carbonaceous material, and other additives. Examples of additives include, but are not limited to, barium sulfate and fibers (such as resin fibers). Note that the negative electrode active material in a charged state is sponge lead, but unformed negative plates are usually made using lead powder.

[0052] (Polymer Compound (P)) Oxy-C contained in polymer compound (P) 2-4 Examples of the alkylene unit include an oxyethylene unit, an oxypropylene unit, an oxytrimethylene unit, an oxy2-methyl-1,3-propylene unit, an oxy1,4-butylene unit, and an oxy1,3-butylene unit. The polymer compound (P) can be formed by adding such an oxyC 2-4 The alkylene unit may have one type or two or more types.

[0053] The polymer compound (P) is a kind of oxy-C 2-4 It may contain an alkylene unit, and two or more kinds of oxy C 2-4 The polymer compound (P) may contain one of the above repeating structures, or may contain two or more of the above repeating structures.

[0054] Examples of the polymer compound (P) include oxy C 2-4 Hydroxy compounds with repeating alkylene units (polyC 2-4 Alkylene glycol, oxy C 2-4 Copolymers containing repeating alkylene units, polyol C 2-4 alkylene oxide adducts, ethers or esters of these hydroxy compounds, etc. are also included.

[0055] As copolymers, different oxy C 2-4 Copolymers containing alkylene units, polyC 2-4 Alkylene glycol alkyl ether, poly C carboxylic acid 2-4 alkylene glycol esters, etc. The copolymer may be a block copolymer.

[0056] The polyol may be any of aliphatic polyols, alicyclic polyols, aromatic polyols, and heterocyclic polyols. From the viewpoint of facilitating thin spreading of the polymer compound on the lead surface, aliphatic polyols and alicyclic polyols (e.g., polyhydroxycyclohexane, polyhydroxynorbornane, etc.) are preferred, and aliphatic polyols are particularly preferred. Examples of aliphatic polyols include aliphatic diols and polyols with triols or more (e.g., glycerin, trimethylolpropane, pentaerythritol, sugars or sugar alcohols, etc.). Examples of aliphatic diols include alkylene glycols with 5 or more carbon atoms. Examples of alkylene glycols include C 5-14 Alkylene glycol or C 5-10 The sugar or sugar alcohol may be, for example, sucrose, erythritol, xylitol, mannitol, sorbitol, etc. The sugar or sugar alcohol may have either a chain structure or a cyclic structure. In the alkylene oxide adduct of polyol, the alkylene oxide is an oxy-C of the polymer compound. 2-4 Corresponding to an alkylene unit, at least C 2-4 The polyol contains an alkylene oxide. From the viewpoint that the polymer compound is likely to have a linear structure, the polyol is preferably a diol.

[0057] The etherified product is the above-mentioned oxy C 2-4 At least some of the terminal -OH groups (-OH groups consisting of a hydrogen atom of the terminal group and an oxygen atom bonded to this hydrogen atom) of the hydroxy compound having a repeating structure of alkylene units are etherified to form -OR 2 group (wherein R 2 is an organic group.) Some or all of the terminals of the polymer compound may be etherified. For example, one terminal of the main chain of a linear polymer compound is an -OH group and the other terminal is an -OR group. 2 It may also be a group.

[0058] The esterified product is the above-mentioned oxy C2-4 At least some of the terminal -OH groups (-OH groups consisting of a hydrogen atom of the terminal group and an oxygen atom bonded to this hydrogen atom) of a hydroxy compound having a repeating structure of alkylene units are esterified to form -OC(=O)-R 3 group (wherein R 3 is an organic group.) Some or all of the terminals of the polymer compound may be esterified. For example, one terminal of the main chain of a linear polymer compound is an -OH group and the other terminal is an -OC(=O)-R 3 It may also be a group.

[0059] organic group R 2 and R 3 Each of the groups includes a hydrocarbon group. The hydrocarbon group may have a substituent (for example, a hydroxy group, an alkoxy group, and / or a carboxy group). The hydrocarbon group may be any of aliphatic, alicyclic, and aromatic. The aromatic hydrocarbon group and the alicyclic hydrocarbon group may have an aliphatic hydrocarbon group (for example, an alkyl group, an alkenyl group, an alkynyl group) as a substituent. The number of carbon atoms in the aliphatic hydrocarbon group as a substituent may be, for example, 1 to 30, 1 to 20, 1 to 10, 1 to 6, or 1 to 4.

[0060] Examples of aromatic hydrocarbon groups include aromatic hydrocarbon groups having 24 or less carbon atoms (e.g., 6 to 24). The number of carbon atoms in the aromatic hydrocarbon group may be 20 or less (e.g., 6 to 20), 14 or less (e.g., 6 to 14), or 12 or less (e.g., 6 to 12). Examples of aromatic hydrocarbon groups include aryl groups and bisaryl groups. Examples of aryl groups include phenyl groups and naphthyl groups. Examples of bisaryl groups include monovalent groups corresponding to bisarenes. Examples of bisarenes include biphenyl and bisarylalkanes (e.g., bisC 6-10 Aryl C 1-4 Alkanes (such as 2,2-bisphenylpropane) are examples.

[0061] Examples of alicyclic hydrocarbon groups include alicyclic hydrocarbon groups having 16 or less carbon atoms. The alicyclic hydrocarbon group may be a bridged cyclic hydrocarbon group. The number of carbon atoms in the alicyclic hydrocarbon group may be 10 or less or 8 or less. The number of carbon atoms in the alicyclic hydrocarbon group may be, for example, 5 or more, or 6 or more.

[0062] The alicyclic hydrocarbon group may have 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) carbon atoms.

[0063] Examples of alicyclic hydrocarbon groups include cycloalkyl groups (cyclopentyl, cyclohexyl, cyclooctyl, etc.), cycloalkenyl groups (cyclohexenyl, cyclooctenyl, etc.), etc. Alicyclic hydrocarbon groups also include hydrogenated products of the above aromatic hydrocarbon groups.

[0064] From the viewpoint of facilitating thin adhesion of the polymer compound to the lead surface, among the hydrocarbon groups, aliphatic hydrocarbon groups are preferred. Examples of aliphatic hydrocarbon groups include alkyl groups, alkenyl groups, alkynyl groups, and dienyl groups. The aliphatic hydrocarbon group may be either linear or branched.

[0065] The number of carbon atoms in the aliphatic hydrocarbon group is, for example, 30 or less, and may be 26 or 22 or less, 20 or 16 or less, 14 or 10 or less, or 8 or 6 or less. The lower limit of the number of carbon atoms depends on the type of aliphatic hydrocarbon group: 1 or more for alkyl groups, 2 or more for alkenyl groups and alkynyl groups, and 3 or more for dienyl groups. Among these, alkyl and alkenyl groups are preferred from the viewpoint of facilitating thin adhesion of the polymer compound to the lead surface.

[0066] Specific examples of alkyl groups include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl, neopentyl, i-pentyl, s-pentyl, 3-pentyl, t-pentyl, n-hexyl, 2-ethylhexyl, n-octyl, n-decyl, i-decyl, lauryl, myristyl, cetyl, stearyl, and behenyl.

[0067] Specific examples of the alkenyl group include vinyl, 1-propenyl, allyl, palmitoleyl, and oleyl. The alkenyl group may be, for example, C 2-30 Alkenyl group or C 2-26 may be an alkenyl group, C 2-22 Alkenyl group or C 2-20 may be an alkenyl group, C 10-20 It may also be an alkenyl group.

[0068] Among polymer compounds, oxy C 2-4 Ethers of hydroxy compounds with repeating alkylene units and oxy-C 2-4 The use of at least one selected from the group consisting of esters of hydroxy compounds having a repeating alkylene unit structure is preferred because it further enhances the effects of the present invention. Furthermore, the use of these polymer compounds also ensures a high liquid loss suppression effect.

[0069] The negative electrode material may contain one type of polymer compound (P), or may contain two or more types of polymer compounds (P).

[0070] From the viewpoint of further enhancing the effect of the present invention, Oxy C 2-4 The repeating alkylene unit preferably contains at least a repeating oxypropylene unit. The polymer compound (P) containing a repeating oxypropylene unit is considered to have an excellent balance of high adsorption to lead and easy thin spreading on the lead surface.

[0071] The polymer compound containing an oxypropylene unit is 1 In the chemical shift of the H-NMR spectrum, peaks due to -CH< and -CH2- of the oxypropylene unit are present in the range of 3.2 ppm to 3.8 ppm. The peaks are split due to differences in electron density around the nuclei of the hydrogen atoms in these groups. Such polymer compounds are 1 In the chemical shift of the H-NMR spectrum, for example, there are peaks in the range of 3.2 ppm to 3.42 ppm and in the range of more than 3.42 ppm to 3.8 ppm. The peak in the range of 3.2 ppm to 3.42 ppm is derived from -CH2-, and the peak in the range of more than 3.42 ppm to 3.8 ppm is derived from -CH< and -CH2-.

[0072] Examples of such polymer compounds (P) include polypropylene glycol, copolymers containing repeating units of oxypropylene, propylene oxide adducts of the above polyols, and etherified or esterified products thereof. Examples of copolymers include oxypropylene-oxyalkylene copolymers (wherein the oxyalkylene is a C alkylene other than oxypropylene). 2-4 Examples of oxypropylene-oxyalkylene copolymers include oxypropylene-oxyethylene copolymers and oxypropylene-oxytrimethylene copolymers. The oxypropylene-oxyalkylene copolymers may be block copolymers.

[0073] In the polymer compound (P) containing a repeating structure of oxypropylene units, the proportion of oxypropylene units in all monomer units may be, for example, 5 mol% or more, 10 mol% or more, 20 mol% or more, 40 mol% or more, 50 mol% or more, 60 mol% or more, or 70 mol% or more.

[0074] The polymer compound is selected from the viewpoint of increasing the adsorption ability to lead and facilitating the formation of a linear structure. 2-4 It is preferable that the polymer compound contains a large number of alkylene units. Such a polymer compound contains, for example, an oxygen atom bonded to the terminal group and a -CH2- group and / or a -CH< group bonded to the oxygen atom. The polymer compound (P) 1 In the H-NMR spectrum, the integral value V1 of the peak between 3.2 ppm and 3.8 ppm is the sum of the integral values ​​of the given peaks V SUM Here, the total integral value of the peak, V SUM is the sum of the peak integral V1, the peak integral of the hydrogen atom of the -CH2- group, and the peak integral of the hydrogen atom of the -CH< group. This ratio is, for example, 50% or more, and may be 80% or more. From the viewpoint of further enhancing the effects of the present invention, the above ratio is preferably 85% or more, and more preferably 90% or more. Such a polymer compound (P) is 2-4 It contains many alkylene units in its molecule, which is thought to make it easier for it to adsorb to lead, and also to easily adopt a linear structure, which makes it easier for it to thinly coat the lead surface.

[0075] When the polymer compound (P) has an -OH group at its terminal and a -CH2- group or a -CH< group bonded to the oxygen atom of the -OH group, 1 In the H-NMR spectrum, the peaks of the hydrogen atoms of the -CH2- group and -CH< group have chemical shifts in the range of more than 3.8 ppm to 4.0 ppm.

[0076] The polymer compound (P) may include a compound having an Mn of 500 or more, may include a compound having an Mn of 600 or more, or may include a compound having an Mn of 1000 or more. The Mn of the polymer compound (P) is, for example, 20000 or less, or may be 15000 or less, or 10000 or less. From the viewpoint of facilitating retention in the negative electrode material and facilitating spreading more thinly on the lead surface, the Mn of the polymer compound (P) is preferably 5000 or less, and may be 4000 or less, or 3000 or less.

[0077] From the viewpoint of facilitating retention of the compound in the negative electrode material and spreading more thinly over the lead surface, the polymer compound (P) preferably contains a polymer compound with an Mn of at least 1000. The Mn of the polymer compound (P) is preferably 1000 to 5000, and may be 1000 to 4000, or may be 1000 to 3000. A polymer compound (P) having such an Mn easily migrates into the negative electrode material even when contained in an electrolyte. Therefore, it is possible to replenish the polymer compound (P) from the electrolyte to the negative electrode material, making it easy to retain the polymer compound (P) in the negative electrode material. Two or more polymer compounds with different Mn may be used as the polymer compound (P). In other words, the polymer compound (P) may have multiple Mn peaks in the molecular weight distribution.

[0078] As described above, the content of the polymer compound (P) in the negative electrode material is 15 ppm or more and 400 ppm or less by mass. The content may be 15 ppm or more (or 50 ppm or more) and 300 ppm or less, 15 ppm or more (or 50 ppm or more) and 200 ppm or less, or 50 ppm or more (or 200 ppm or more) and 400 ppm or less.

[0079] (organic shrinkage preventer) The negative electrode material may contain an organic shrinkage inhibitor. The organic shrinkage inhibitor may be a known organic shrinkage inhibitor used in lead-acid batteries. The organic shrinkage inhibitor may be at least one selected from the group consisting of lignin compounds and synthetic organic shrinkage inhibitors. Examples of lignin compounds include lignin and lignin derivatives. Examples of lignin derivatives include lignin sulfonic acid or its salts (such as alkali metal salts (sodium salts)). Organic shrinkage inhibitors are generally broadly classified into lignin compounds and synthetic organic shrinkage inhibitors. Synthetic organic shrinkage inhibitors can also be considered organic shrinkage inhibitors other than lignin compounds. Synthetic organic shrinkage inhibitors are organic polymers containing sulfur and generally contain multiple aromatic rings in the molecule and sulfur as a sulfur-containing group. Among the sulfur-containing groups, a sulfonic acid group or a sulfonyl group, which are stable, is preferred. The sulfonic acid group may exist in an acid form or a salt form, such as a sodium salt. The negative electrode material may contain one or more organic shrinkage inhibitors.

[0080] The synthetic organic shrink-preventing agent may be a condensation product containing at least an aromatic compound unit. Examples of such condensation products include condensation products of aromatic compounds with aldehyde compounds (at least one selected from the group consisting of aldehydes (e.g., formaldehyde) and condensation products thereof). The organic shrink-preventing agent may contain one type of aromatic compound unit, or two or more types of aromatic compound units. The aromatic compound unit refers to a unit derived from an aromatic compound incorporated into the condensation product. Examples of aromatic compounds include bisphenol A, bisphenol S, and bisphenol F.

[0081] The content of the organic shrinkage inhibitor in the negative electrode material is, for example, 0.01% by mass or more, and may be 0.05% by mass or more, and for example, 1.0% by mass or less, and may be 0.5% by mass or less.

[0082] The content of the organic shrinkage inhibitor in the negative electrode material may be 0.01% by mass or more and 1.0% by mass or less, 0.05% by mass or more and 1.0% by mass or less, 0.01% by mass or more and 0.5% by mass or less, or 0.05% by mass or more and 0.5% by mass or less.

[0083] (carbonaceous material) Examples of the carbonaceous material contained in the negative electrode material include carbon black, graphite, hard carbon, and soft carbon. Examples of carbon black include acetylene black, furnace black, and lamp black. Furnace black also includes Ketjen Black (trade name). The graphite may be any carbonaceous material containing a graphite-type crystalline structure, and may be either artificial graphite or natural graphite. The negative electrode material may contain one type of carbonaceous material, or two or more types.

[0084] The content of the carbonaceous material in the negative electrode material is, for example, 0.05% by mass or more, or may be 0.10% by mass or more, and the content of the carbonaceous material is, for example, 5% by mass or less, or may be 3% by mass or less.

[0085] The content of the carbonaceous material in the negative electrode material may be 0.05% by mass to 5% by mass, 0.05% by mass to 3% by mass, 0.10% by mass to 5% by mass, or 0.10% by mass to 3% by mass.

[0086] (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, and 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.

[0087] The content of barium sulfate in the negative electrode material may be 0.05% by mass to 3% by mass, 0.05% by mass to 2% by mass, 0.10% by mass to 3% by mass, or 0.10% by mass to 2% by mass.

[0088] (Analysis of the components of negative electrode materials) The following describes the method for analyzing the negative electrode material or its constituent components. Prior to analysis, a fully charged lead-acid 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 washing is continued until a pH test paper is pressed against the washed surface of the negative electrode plate and no color change is confirmed. However, the washing time should be within two hours. The washed negative electrode plate is dried in a reduced pressure environment at 60±5°C for approximately six hours. If the negative electrode plate contains an adhesive material, the adhesive material is removed as necessary. Next, the negative electrode material is separated from the negative electrode plate and pulverized to obtain a sample (hereinafter referred to as Sample A).

[0089] (1) Analysis of polymer compounds (1-1) Qualitative analysis of polymer compounds 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. The solids are then removed by filtration. The polymer compound obtained by extraction is dissolved in a chloroform solution, or the polymer compound obtained by drying the chloroform solution is identified by obtaining information from at least one of infrared spectroscopy, ultraviolet-visible absorption spectroscopy, NMR spectroscopy, LC-MS, and pyrolysis GC-MS.

[0090] The chloroform-soluble matter is recovered by distilling off the chloroform under reduced pressure from the chloroform solution in which the polymer compound obtained by extraction is dissolved. The chloroform-soluble matter is dissolved in deuterated chloroform and subjected to the following conditions: 1 1H-NMR spectrum is measured. 1 From the H-NMR spectrum, a peak with a chemical shift in the range of 3.2 ppm to 3.8 ppm is confirmed. Also, from the peak in this range, oxy C 2-4 Identify the type of alkylene unit.

[0091] Apparatus: AL400 nuclear magnetic resonance spectrometer manufactured by JEOL Ltd. Observation frequency: 395.88MHz Pulse width: 6.30 μs Pulse repetition time: 74.1411 seconds Accumulation count: 32 Measurement temperature: room temperature (20~35℃) Standard: 7.24 ppm Sample tube diameter: 5 mm

[0092] 1 From the H-NMR spectrum, the integral value (V1) of the peaks present in the chemical shift range of 3.2 ppm to 3.8 ppm is determined. In addition, for each of the hydrogen atoms of the -CH2- group and -CH< group bonded to the oxygen atom bonded to the terminal group of the polymer compound, 1 The sum of the integral values ​​of the peaks in the H-NMR spectrum (V2) is calculated. Then, from V1 and V2, the percentage of V1 in the total of V1 and V2 (= 100 × V1 / (V1 + V2), unit: %) is calculated.

[0093] In addition, in qualitative analysis, 1 When calculating the integral value of a peak in a H-NMR spectrum, 1 In the H-NMR spectrum, two points without significant signals are determined on either side of the peak, and the line connecting these two points is used as the baseline to calculate each integral value. For example, for a peak with a chemical shift in the range of 3.2 ppm to 3.8 ppm, the line connecting the two points at 3.2 ppm and 3.8 ppm in the spectrum is used as the baseline. For example, for a peak with a chemical shift in the range of more than 3.8 ppm but not more than 4.0 ppm, the line connecting the two points at 3.8 ppm and 4.0 ppm in the spectrum is used as the baseline.

[0094] (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 1H-NMR spectrum is measured.1 The H-NMR spectrum is measured. Next, 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.

[0095] 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 whose chemical shift shows a peak in the range of 3.2 to 3.8 ppm (more specifically, oxy C 2-4 (molecular weight of repeating alkylene units) and N a is the number of hydrogen atoms attached to the carbon atoms in the main chain of the repeating unit. r、 M r are the number of hydrogen atoms contained in the molecule of the reference material, the molecular weight of the reference material, and m (g) is the mass of the negative electrode material used for extraction. In this analysis, the reference substance is TCE, so N r =2, M r = 168. Also, m = 100.

[0096] For example, when the polymer compound (P) is polypropylene glycol, M a is 58, and N a is 3. When the polymer compound (P) is polyethylene glycol, M a is 44, and N a is 4. N a and M a is the N of each monomer unit a Value and M a The value is an average value obtained by using the molar ratio (mol %) of each monomer unit contained in the repeating structure.

[0097] In quantitative analysis, 1 The integral value of the peak in the H-NMR spectrum is determined using data processing software "ALICE" manufactured by JEOL Ltd.

[0098] (1-3) Mn measurement of polymer compounds GPC measurement of the polymer compound extracted from sample A by the method described in (1-1) above is carried out using the following apparatus under the following conditions. Separately, a calibration curve (calibration curve) is created by plotting the Mn of the standard substance versus elution time. Based on this calibration curve and the GPC measurement results of the polymer compound, the Mn (number average molecular weight) of the polymer compound is calculated.

[0099] Analysis system: 20A system (Shimadzu Corporation) Column: Two GPC KF-805L (Shodex) columns connected in series Column temperature: 30℃ Mobile phase: tetrahydrofuran Flow rate: 1mL / min. Concentration: 0.20% by mass Injection volume: 10μL Standard substance: polyethylene glycol (Mn = 200,0000, 20,0000, 20,000, 2,000, 200) Detector: Differential refractive index detector (Shodex RI-201H)

[0100] (2) Analysis of organic shrinkage inhibitors (2-1) Qualitative analysis of organic shrinkage inhibitors in negative electrode materials Sample A is immersed in a 1 mol / L aqueous solution of sodium hydroxide to extract the organic shrink-control agent. Next, if necessary, the first organic shrink-control agent and the second organic shrink-control agent are separated from the extract. For each of the separated organic shrink-control agents, insoluble components are removed by filtration, and the resulting solution is desalted, concentrated, and dried. 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. A powder sample of the organic shrink-control agent (hereinafter referred to as Sample B) is obtained by drying.

[0101] The type of organic shrink-proofing agent can be identified by combining information obtained from the infrared spectrum measured using sample B of the organic shrink-proofing agent obtained in this manner, the ultraviolet-visible absorption spectrum measured using an ultraviolet-visible absorption spectrometer after diluting sample B with distilled water or the like, the NMR spectrum of a solution obtained by dissolving sample B in a specified solvent such as heavy water, or information obtained from pyrolysis GC-MS or the like which can provide information on the individual compounds that make up the substance.

[0102] The first and second organic shrink-control agents are separated from the extract as follows. First, the extract is analyzed by infrared spectroscopy, NMR, and / or GC-MS to determine whether it contains multiple organic shrink-control agents. Next, the extract is analyzed by GPC to measure its molecular weight distribution. If the multiple organic shrink-control agents can be separated by molecular weight, the organic shrink-control agents are separated by column chromatography based on their molecular weight differences. If separation based on molecular weight differences is difficult, one of the organic shrink-control agents is separated by precipitation separation, utilizing the differences in solubility depending on the type and / or amount of functional groups possessed by the organic shrink-control agents. Specifically, the extract is dissolved in an aqueous NaOH solution, and a sulfuric acid solution is added dropwise to adjust the pH of the mixture to flocculate and separate one of the organic shrink-control agents. The separated material is then dissolved again in an aqueous NaOH solution, and the insoluble components are removed by filtration as described above. The remaining solution after separating the one of the organic shrink-control agents is concentrated. The resulting concentrate contains the other organic shrinkage inhibitor, and the insoluble components are removed from the concentrate by filtration as described above.

[0103] (2-2) Quantitative determination of the content of organic shrinkage inhibitor in negative electrode material As in (2-1) above, for each of the separated products containing the organic shrinkage inhibitor, insoluble components are removed by filtration to obtain a solution. The ultraviolet-visible absorption spectrum of each of the obtained solutions is measured. The content of each organic shrinkage inhibitor in the negative electrode material is determined using the intensity of the peak characteristic of each organic shrinkage inhibitor and a previously prepared calibration curve.

[0104] When obtaining a lead-acid battery with an unknown content of organic shrinkage preventer and measuring the content of the organic shrinkage preventer, it may be impossible to precisely identify the structural formula of the organic shrinkage preventer, and therefore the same organic shrinkage preventer cannot be used for the calibration curve. In this case, a calibration curve is created using a separately available organic polymer that shows similar shapes in the ultraviolet-visible absorption spectrum, infrared spectroscopy spectrum, NMR spectrum, etc. to the organic shrinkage preventer extracted from the negative electrode of the battery, and the content of the organic shrinkage preventer is measured using the ultraviolet-visible absorption spectrum.

[0105] (2-3) Sulfur content in organic shrinkage inhibitors As in (2-1) above, sample B of the organic shrink-proofing agent is obtained, and then the sulfur element in 0.1 g of the organic shrink-proofing agent is converted to sulfuric acid using the oxygen combustion flask method. Sample B is then burned in a flask containing an adsorption solution, yielding an eluate in which sulfate ions have dissolved in the adsorption solution. The eluate is then titrated with barium perchlorate using thorin as an indicator to determine the sulfur element content (c1) in 0.1 g of the organic shrink-proofing agent. Next, c1 is multiplied by 10 to calculate the sulfur element content (μmol / g) per gram of the organic shrink-proofing agent.

[0106] (2-4) Mw measurement of organic shrinkage inhibitors After obtaining sample B of the organic shrink-proofing agent in the same manner as in (2-1) above, GPC measurement of the organic shrink-proofing agent is carried out using the following apparatus under the following conditions. Separately, a calibration curve (calibration curve) is created from a plot of the Mw of the standard substance versus elution time. Based on this calibration curve and the GPC measurement results of the organic shrink-proofing agent, the Mw of the organic shrink-proofing agent is calculated.

[0107] GPC equipment: Build-up GPC system SD-8022 / DP-8020 / AS-8020 / CO-8020 / UV-8020 (Tosoh Corporation) Column: TSKgel G4000SWXL, G2000SWXL (7.8 mm I.D. x 30 cm) (Tosoh Corporation) Detector: UV detector, λ=210nm Eluent: A mixture of 1 mol / L NaCl aqueous solution and acetonitrile (volume ratio = 7:3) Flow rate: 1mL / min. Concentration: 10mg / mL Injection volume: 10μL Standard substance: Polystyrene sulfonate sodium (Mw = 275,000, 35,000, 12,500, 7,500, 5,200, 1,680)

[0108] (3) Quantitative analysis of carbonaceous materials and barium sulfate 50 ml of 20% by mass nitric acid was added to 10 g of sample A and heated for approximately 20 minutes to dissolve the lead component as lead nitrate. Next, the solution containing lead nitrate was filtered to separate out solids such as carbonaceous materials and barium sulfate.

[0109] The obtained solid content is dispersed in water to form a dispersion, and then components other than the carbonaceous material and barium sulfate (e.g., reinforcing material) are removed from the dispersion using a sieve. Next, the dispersion is subjected to suction filtration using a membrane filter whose mass has been measured in advance, and the membrane filter together with the filtered sample is dried in a dryer at 110°C ± 5°C. The filtered sample is a mixed sample of the carbonaceous material and barium sulfate. The mass of the membrane filter is subtracted from the total mass of the dried mixed sample (hereinafter referred to as Sample C) and the membrane filter to determine the mass of Sample C (M m ) is measured. Then, sample C is placed in a crucible together with the membrane filter and burnt at 1300°C or higher to be incinerated. The remaining residue is barium oxide. The mass of barium oxide is converted to the mass of barium sulfate to determine the mass of barium sulfate (M B ) to find the mass M m to mass M B The mass of the carbonaceous material is calculated by subtracting the above.

[0110] (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 chemically forming the unformed negative electrode plate. 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, if necessary, at least one selected from the group consisting of an organic shrinkage inhibitor, a carbonaceous material, and other additives, and kneading the mixture. When aging, it is preferable to age the unformed negative electrode plate at a temperature higher than room temperature and at high humidity.

[0111] The formation can be carried out by immersing an electrode plate assembly including unformed negative plates in an electrolyte containing sulfuric acid in a battery jar of a lead-acid battery and then charging the electrode plate assembly. However, the formation can also be carried out before assembling the lead-acid battery or the electrode plate assembly. The formation produces spongy lead.

[0112] (positive electrode plate) Positive electrode plates for lead-acid batteries can be classified into paste-type and clad-type. Paste-type positive electrode plates include a positive electrode collector and a positive electrode material. The positive electrode material is held by the positive electrode collector. In a paste-type positive electrode plate, the positive electrode material is the portion of the positive electrode plate excluding the positive electrode collector. The positive electrode collector may be formed by casting lead (Pb) or a lead alloy, or by processing a lead sheet or a lead alloy sheet. Examples of processing methods include expanding and punching. A lattice-shaped current collector is preferred as the positive electrode collector because it facilitates the support of the positive electrode material. A clad-type positive electrode plate includes multiple porous tubes, cores inserted into each tube, a current collector connecting the multiple cores, positive electrode material filled in the tubes with the cores inserted, and a connecting seat connecting the multiple tubes. In a clad-type positive electrode plate, the positive electrode material is the portion excluding the tube, the core metal, the current collector, and the connecting seat. In a clad-type positive electrode plate, the core metal and the current collector are sometimes collectively referred to as the positive electrode current collector.

[0113] A positive electrode plate may have a mat, pasting paper, or other such material attached to it. Such materials (attaching materials) are used integrally with the positive electrode plate and are therefore considered to be included in the positive electrode plate. Furthermore, when the positive electrode plate includes an attaching material (mat, pasting paper, etc.), the positive electrode material, in the case of a paste-type positive electrode plate, is the positive electrode plate excluding the positive electrode current collector and the attaching material.

[0114] As the lead alloy used for the positive electrode current collector, a Pb-Sb alloy, a Pb-Ca alloy, or a Pb-Ca-Sn alloy is preferred in terms of corrosion resistance and mechanical strength. The positive electrode current collector may have a surface layer. The surface layer and the inner layer of the positive electrode current collector may have different compositions. 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, the lug portion, or the frame portion of the positive electrode current collector.

[0115] The positive electrode material contained in the positive electrode plate includes a positive electrode active material (lead dioxide or lead sulfate) that generates capacity through an oxidation-reduction reaction. The positive electrode material may also contain other additives as needed.

[0116] Unformed paste-type positive plates are obtained by filling a positive current collector with positive electrode paste, aging it, and drying it. The positive electrode paste is prepared by kneading lead powder, additives, water, and sulfuric acid. Unformed clad-type positive plates are formed by filling porous tubes with lead powder or lead powder slurry, into which core metals connected by current collectors are inserted, and then connecting multiple tubes with a connecting rod. These unformed positive plates are then chemically formed to obtain positive plates. Chemical formation can be performed by charging a plate group including unformed positive plates while immersing them in an electrolyte containing sulfuric acid in a lead-acid battery container. However, chemical formation may also be performed before assembling the lead-acid battery or plate group.

[0117] The formation can be performed by immersing an electrode plate assembly including unformed positive plates in an electrolyte containing sulfuric acid in a battery container of a lead-acid battery and charging the electrode plate assembly, but the formation may also be performed before assembling the lead-acid battery or the electrode plate assembly.

[0118] (separator) A separator can be disposed between the negative electrode plate and the positive electrode plate, and the separator is made of at least one material selected from a nonwoven fabric and a microporous membrane.

[0119] A nonwoven fabric is a mat of intertwined fibers without being woven, and is primarily composed of fibers. For example, 60% by mass or more of the nonwoven fabric is made of fibers. Examples of fibers that can be used include glass fibers, polymer fibers (polyolefin fibers, acrylic fibers, polyester fibers (polyethylene terephthalate fibers, etc.)), and pulp fibers. Of these, glass fibers are preferred. The nonwoven fabric may contain components other than fibers, such as acid-resistant inorganic powders and polymers as binders.

[0120] On the other hand, a microporous membrane is a porous sheet mainly composed of components other than fiber components, and can be obtained, for example, by extruding a composition containing a pore-forming agent into a sheet, and then removing the pore-forming agent to form pores. The microporous membrane is preferably made of an acid-resistant material, and preferably is mainly composed of a polymer component. The polymer component is preferably polyolefin (polyethylene, polypropylene, etc.). The pore-forming agent can be at least one selected from the group consisting of polymer powder and oil.

[0121] The separator may be made of, for example, only a nonwoven fabric or only a microporous membrane. Furthermore, the separator may be a laminate of a nonwoven fabric and a microporous membrane, a laminate of different or the same materials, or a laminate of different or the same materials with recesses and protrusions interlocked, as needed.

[0122] The separator may be sheet-shaped or bag-shaped. A single sheet-shaped separator may be sandwiched between the positive electrode plate and the negative electrode plate. Alternatively, the electrode plates may be sandwiched between a single folded sheet-shaped separator. In this case, a positive electrode plate sandwiched between folded sheet-shaped separators may be stacked on top of a negative electrode plate sandwiched between folded sheet-shaped separators, or one of the positive electrode plate and the negative electrode plate may be sandwiched between folded sheet-shaped separators and stacked on top of the other electrode plate. Alternatively, a sheet-shaped separator may be folded into an accordion-like shape, and the positive electrode plate and the negative electrode plate may be sandwiched between the accordion-like separators so that the separator is interposed between them. When a separator folded like an accordion is used, the separator may be arranged so that the folded portion is aligned with the horizontal direction of the lead-acid battery (e.g., so that the folded portion is parallel to the horizontal direction) or so that the folded portion is aligned with the vertical direction (e.g., so that the folded portion is parallel to the vertical direction). In a separator folded like an accordion, recesses are formed alternately on both main surfaces of the separator. Because the positive and negative plates usually have lugs on the top, when the separator is arranged so that the folded portion is aligned with the horizontal direction of the lead-acid battery, the positive and negative plates are placed in the recesses on only one main surface of the separator (i.e., a double separator is interposed between adjacent positive and negative plates). When the separator is arranged so that the folded portion is aligned with the vertical direction of the lead-acid battery, the positive electrode plate can be accommodated in the recess on one main surface side, and the negative electrode plate can be accommodated in the recess on the other main surface side (that is, a single separator can be interposed between adjacent positive and negative electrode plates.) When a pouch-shaped separator is used, the pouch-shaped separator may accommodate either the positive electrode plate or the negative electrode plate.

[0123] (electrolyte) The electrolytic solution is an aqueous solution containing sulfuric acid, which may be gelled as necessary. The electrolytic solution may contain the above-mentioned polymer compound (P).

[0124] The electrolytic solution may contain cations (e.g., metal cations) and / or anions (e.g., anions other than sulfate anions (e.g., phosphate ions)) as needed. Examples of metal cations include at least one selected from the group consisting of Na ions, Li ions, Mg ions, and Al ions.

[0125] The specific gravity of the electrolyte in a fully charged lead-acid battery at 20°C is, for example, 1.20 or more, and may be 1.25 or more. The specific gravity of the electrolyte at 20°C is 1.35 or less, and preferably 1.32 or less.

[0126] 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.

[0127] (others) A lead-acid battery can be obtained by a manufacturing method including a step of housing a plate assembly and an electrolyte in a cell chamber of a battery case. Each cell of the lead-acid battery includes a plate assembly and an electrolyte housed in each cell chamber. The plate assembly is assembled by stacking positive electrode plates, negative electrode plates, and a separator with the separator interposed between the positive electrode plates and the negative electrode plates prior to housing in the cell chamber. The positive electrode plates, negative electrode plates, electrolyte, and separator are each prepared prior to assembling the plate assembly. The manufacturing method of the lead-acid battery may include a step of chemically converting at least one of the positive electrode plates and the negative electrode plates, as necessary, after the step of housing the plate assembly and the electrolyte in the cell chamber.

[0128] The number of plates in the electrode plate group may be one or two or more. From the viewpoint of ensuring higher capacity, the number of negative electrode plates included in the electrode plate group is preferably two or more, and may be four or more, or six or more. Note that, if the number of negative electrode plates included in the electrode plate group is n, the number of positive electrode plates is (n-1) or more and (n+1) or less when n≧2, and is 1 or 2 when n=1.

[0129] When a lead-acid battery has two or more cells, at least one cell satisfies the above conditions, and preferably all cells satisfy the above conditions.

[0130] When a separator and a mat are used in combination in an electrode plate assembly, or when a mat mainly made of nonwoven fabric is attached to an electrode plate, the thickness of the electrode plate includes the thickness of the mat, because the mat is used integrally with the electrode plate. However, when a mat is attached to a separator, the thickness of the mat is included in the thickness of the separator.

[0131] FIG. 1 shows the external appearance of an example of a lead-acid battery according to one embodiment of the present invention. The lead-acid battery 1 includes a battery case 12 that contains a plate group 11 and an electrolyte (not shown). The battery case 12 is divided into multiple cell chambers 14 by partition walls 13. Each cell chamber 14 contains one plate group 11. The opening of the battery case 12 is closed with a lid 15 that includes a negative electrode terminal 16 and a positive electrode terminal 17. The lid 15 is provided with a vent plug 18 for each cell chamber. When rehydrating, the vent plug 18 is removed and rehydration liquid is added. The vent plug 18 may have a function of venting gas generated in the cell chambers 14 to the outside of the battery.

[0132] Each electrode plate group 11 is formed by stacking multiple negative electrode plates 2 and multiple positive electrode plates 3 with separators 4 interposed between them. Here, a pouch-shaped separator 4 is shown housing the negative electrode plates 2, but the shape of the separator is not particularly limited. In a cell chamber 14 located at one end of the battery case 12, a negative electrode shelf 6 that connects multiple negative electrode plates 2 in parallel is connected to a through-connector 8, and a positive electrode shelf 5 that connects multiple positive electrode plates 3 in parallel is connected to a positive electrode column 7. The positive electrode column 7 is connected to a positive electrode terminal 17 outside the lid 15. In a cell chamber 14 located at the other end of the battery case 12, a negative electrode column 9 is connected to the negative electrode shelf 6, and a through-connector 8 is connected to the positive electrode shelf 5. The negative electrode column 9 is connected to a negative electrode terminal 16 outside the lid 15. Each through-connector 8 passes through a through-hole provided in the partition wall 13 to connect the electrode plate groups 11 of adjacent cell chambers 14 in series.

[0133] The positive electrode shelf 5 is formed by welding the lugs provided on the top of each positive electrode plate 3 together using a cast-on-strap method or a burning method. The negative electrode shelf 6 is also formed by welding the lugs provided on the top of each negative electrode plate 2 together in the same manner as the positive electrode shelf 5.

[0134] The lid 15 of the lead-acid battery has a single structure (single lid), but this is not limited to the illustrated example. The lid 15 may have a double structure including, for example, an inner lid and an outer lid (or top lid). A lid having a double structure may have a reflux structure between the inner lid and the outer lid for returning the electrolyte to the battery (inside the inner lid) from a reflux port provided in the inner lid.

[0135] A lead-acid battery according to one aspect of the present invention will be summarized below. (1) A group of electrodes; An electrolyte; a battery case that contains the electrode plate group and the electrolyte; the electrode plate group includes a plurality of stacked positive electrode plates and a plurality of stacked negative electrode plates, the negative electrode plate includes a negative electrode material, the negative electrode material includes a polymer compound; The polymer compound is measured using deuterated chloroform as a solvent. 1 The chemical shift of the H-NMR spectrum has a peak in the range of 3.2 ppm to 3.8 ppm, the content of the polymer compound in the negative electrode material is 15 ppm or more and 400 ppm or less by mass, a pull-out load when the electrode plate group is pulled out of the battery case is 1.5 times or more the weight of the electrode plate group itself.

[0136] (2) a group of electrodes; An electrolyte; a battery case that contains the electrode plate group and the electrolyte; the electrode plate group includes a plurality of stacked positive electrode plates and a plurality of stacked negative electrode plates, the negative electrode plate includes a negative electrode material, the negative electrode material includes a polymer compound; The polymer compound is oxy C 2-4 Contains alkylene units as a repeating structure, the content of the polymer compound in the negative electrode material is 15 ppm or more and 400 ppm or less by mass, a pull-out load when the electrode plate group is pulled out of the battery case is 1.5 times or more the weight of the electrode plate group itself.

[0137] (3) In the above (2), the polymer compound is the oxy C 2-4 The composition may contain at least one selected from the group consisting of a hydroxy compound containing the repeating structure of an alkylene unit, an etherified product of the hydroxy compound, and an esterified product of the hydroxy compound.

[0138] (4) In the above (1) or (2), the polymer compound may be at least one selected from the group consisting of polyethylene glycol, an esterified product of polyethylene glycol, polypropylene glycol, and an esterified product of polypropylene glycol.

[0139] (5) In the above (4), the polymer compound may be polypropylene glycol.

[0140] (6) In any one of the above (1) to (5), the polymer compound may have a number average molecular weight of 1,000 or more.

[0141] (7) In any one of the above (1) to (6), the pull-out load when the electrode plate group is pulled out of the battery case may be 10.0 times or less the weight of the electrode plate group itself.

[0142] Another example of a lead-acid battery (X) disclosed in this specification includes a plate assembly, an electrolyte, and a battery case containing the plate assembly and the electrolyte. The plate assembly includes a plurality of stacked positive and negative electrode plates, and the load required to remove the plate assembly from the battery case is 1.5 times or more the weight of the plate assembly. The lead-acid battery (X) may or may not contain a polymer compound (P). For example, the content of the polymer compound (P) in the negative electrode material of the lead-acid battery (X) may be less than 15 ppm by mass (e.g., greater than 0 ppm and less than 15 ppm). The components other than the polymer compound (P) can be configured similarly to the aforementioned lead-acid battery containing the polymer compound (P). The lead-acid battery (X) can achieve high charge acceptance, as shown in the examples.

[0143] [Example] The present invention will be specifically described below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0144] [Measurement and evaluation of overcharged electricity quantity] In the examples, the overcharge quantity of electricity is measured and evaluated as follows. First, a 1220-cycle high-temperature light-load test is performed at 75°C ± 3°C on the lead-acid battery to achieve overcharge conditions greater than those of the standard 4-10 minute test specified in JIS D5301. The high-temperature load test is performed with the lead-acid battery placed in a water tank at 75°C. One cycle of the high-temperature light-load test consists of a 1-minute discharge and a 10-minute charge. Discharge is performed at a current of 25 A. Charging is performed at a voltage of 2.47 V / cell and a current of 25 A. The overcharge quantity of electricity (charge quantity of electricity - discharge quantity of electricity) for each cycle from 1 to 1220 is then added together to obtain a total value. Next, the total value is divided by the number of cycles to obtain the overcharge quantity of electricity (Ah) per cycle. The smaller the overcharge quantity of electricity, the better the battery characteristics and the less electrolyte loss there is. The overcharge quantity of electricity of each battery was evaluated based on the relative value (ratio) of the overcharge quantity of electricity (Ah) of each battery when the overcharge quantity of electricity (Ah) per cycle of battery A1 was set to 100. The lower the relative value, the better the characteristics.

[0145] [Charging acceptance performance evaluation] In the examples, charge acceptance was measured and evaluated using the following method. First, the lead-acid battery to be measured was fully charged by charging it according to the method described for "fully charged state." Next, the battery was discharged at 6.4 A for 30 minutes, left for 16 hours, and then charged at a constant voltage of 2.42 V / cell. The upper limit of the charging current was 200 A. The cumulative charge amount (Ah) was measured for 10 seconds from the start of charging. These procedures were performed with the battery placed in a water tank at 25°C ± 2°C. A larger cumulative charge amount (Ah) indicates higher charge acceptance (battery characteristics are better). The charge acceptance of each battery was evaluated based on the relative value (ratio) of the cumulative charge amount (Ah) of each battery when the cumulative charge amount (Ah) of battery A1 was set to 100. A higher relative value indicates better characteristics.

[0146] [Evaluation of the incidence of permeation short circuits] In the examples, the incidence of permeable short circuits is evaluated by the following method. The term "permeable short circuit" refers to a short circuit that occurs when dendrites or the like growing from an electrode penetrate the separator and reach an adjacent electrode. To evaluate the incidence of permeable short circuits, 20 lead-acid batteries to be evaluated were first prepared. These lead-acid batteries were then placed in a thermostatic water bath at 25°C, and a charge-discharge cycle consisting of the following steps 1 to 4 was repeated five times. This test was conducted under conditions that promote the occurrence of permeable short circuits. Therefore, the incidence of permeable short circuits in this test was significantly higher than the incidence of permeable short circuits under actual usage conditions of lead-acid batteries. Step 1: Discharge the lead-acid battery at a constant current of 0.05 C (A) until the voltage reaches 1.0 V / cell. Here, C is the rated capacity expressed in units of Ah (ampere-hours). Step 2: Connect a 10 Ω resistor to the lead-acid battery that has gone through step 1 and discharge it for 28 days. Step 3: The lead-acid battery that has passed through step 2 is charged for 10 minutes at a constant voltage of 2.4V / cell, with a maximum charging current of 50A. Step 4: Charge at a constant current of 0.05 C(A) for 27 hours.

[0147] Next, the 20 lead-acid batteries that had undergone the above charge-discharge cycle were disassembled and visually inspected for the presence or absence of short circuits. From this test, the incidence of short circuits (permeable short circuits) was determined.

[0148] Example 1 In Example 1, several types of lead-acid batteries are produced by varying the content of the polymer compound (P) in the negative electrode material and the pull-out load of the electrode plate assembly. The positive and negative electrode plates of these lead-acid batteries are produced as follows.

[0149] (a) Preparation of the negative electrode plate The raw materials, lead powder, barium sulfate, carbon black, a polymer compound (P) (polypropylene glycol, Mn=2000), and an organic shrinkage preventer (sodium lignin sulfonate), are mixed with an appropriate amount of aqueous sulfuric acid solution to obtain a negative electrode paste. The components are mixed so that the polypropylene glycol (PPG) content (ppm: mass ratio) in the negative electrode material, as determined by the procedure described above, is the amount shown in Table 1. The components are also mixed so that the barium sulfate content, carbon black content, and organic shrinkage preventer content in the negative electrode material are 0.4 mass% by weight, 0.2 mass% by weight, and 0.1 mass% by weight, respectively. The negative electrode paste is filled into the mesh portion of a Pb-Ca-Sn alloy expanded grid, aged, and dried to obtain an unformed negative electrode plate.

[0150] (b) Preparation of the positive electrode plate The raw lead powder is mixed with an aqueous sulfuric acid solution to obtain a positive electrode paste, which is then filled into the mesh of a Pb-Ca-Sn alloy expanded grid, aged, and dried to obtain an unformed positive electrode plate.

[0151] (c) Preparation of test battery The test battery has a rated voltage of 2V and a 20-hour rate rated capacity of 60Ah. The test battery's electrode plate assembly consists of seven positive plates and eight negative plates. The positive plates are housed in a pouch-shaped separator made of a microporous polyethylene film and are stacked alternately with the negative plates to form an electrode plate assembly. The electrode plate assembly is housed in a polypropylene battery case together with an electrolyte (aqueous sulfuric acid solution), and an electrochemical reaction is carried out inside the case to create a liquid lead-acid battery. The specific gravity of the electrolyte after electrochemical reaction is 1.28 (calculated at 20°C).

[0152] When preparing the test battery, spacers are placed between the inner wall of the battery case and the electrode plates at the ends of the electrode assembly, as necessary. The thickness of the spacers is adjusted so that the pull-out load (the pull-out load of the electrode assembly) changes. The thicknesses of the negative and positive electrodes are 1.5 mm and 1.8 mm, respectively, and the maximum thickness T of the separator is 0.8 mm.

[0153] In addition, the polymer compound measured by the above-mentioned procedure 1 In the H-NMR spectrum, peaks derived from -CH2- of the oxypropylene unit are observed in the chemical shift range of 3.2 ppm to 3.42 ppm, and peaks derived from -CH< and -CH2- of the oxypropylene unit are observed in the chemical shift range of more than 3.42 ppm to 3.8 ppm. 1 In the H-NMR spectrum, the integral value V1 of the peaks between 3.2 ppm and 3.8 ppm is the sum of the integral values ​​of the specified peaks V SUM The percentage of the total integral value is 98.1%. SUM is the sum of the integral V1, the integral of the peak of the hydrogen atom of the -CH2- group bonded to the oxygen atom, and the integral of the peak of the hydrogen atom of the -CH< group bonded to the oxygen atom.

[0154] The lead-acid batteries fabricated as described above were evaluated for overcharge electricity quantity, charge acceptance performance, incidence of penetrating short circuit, and pull-out load ratio using the methods described above. Tables 1 and 2 show some of the fabrication conditions and the evaluation results for the lead-acid batteries fabricated.

[0155] [Table 1]

[0156] [Table 2]

[0157] The notes in Tables 1 and 2 indicate the following: (*1) (Pull-out load ratio) = (Pull-out load of electrode plate group) / (Weight of electrode plate group) (*2) Relative values ​​are ratios when the measured value of lead-acid battery A1 is set to 100. (*3) Batteries with a relative value of 95 or less are rated A (good), batteries with a relative value between 95 and 100 are rated B (acceptable), and batteries with a relative value greater than 100 are rated C (unacceptable). (*4) Batteries with a relative value of 105 or more are rated A (good), batteries with a relative value of 100 or more but less than 105 are rated B (acceptable), and batteries with a relative value of less than 100 are rated C (unacceptable). (*5) Lead-acid batteries with a permeation short circuit occurrence rate of 10% or less are rated as A (good), and batteries with a rate of occurrence exceeding 10% are rated as C (unacceptable).

[0158] As shown in Tables 1 and 2, a lead-acid battery having a withdrawal load ratio of 1.5 or more and a polymer (P) content of 15 ppm or more and 400 ppm or less has a small overcharge quantity of electricity, a high charge acceptance performance, and a low incidence of permeable short circuits. That is, the lead-acid battery can achieve a good balance of a small overcharge quantity of electricity, a high charge acceptance performance, and a low incidence of permeable short circuits.

[0159] When the PPG content is 0 ppm, increasing the withdrawal load improves charge acceptance, but the amount of overcharge electricity increases. As the amount of overcharge electricity increases, gas generation during overcharge increases, leading to greater electrolyte loss. Also, when the PPG content is 0 ppm, increasing the withdrawal load significantly increases the incidence of permeation short circuits.

[0160] When the extraction load ratio is 1.4 or less, the charge acceptance performance decreases significantly as the content of the polymer compound (P) increases. On the other hand, when the extraction load ratio is 1.5 or more, the charge acceptance performance does not decrease significantly even if the content of the polymer compound (P) increases within the range of 15 ppm to 400 ppm. When the content of the polymer compound (P) is 500 ppm, the decrease in charge acceptance becomes significant.

[0161] When the pull-out load ratio is 1.5 or more, the charge acceptance is improved when the content of the polymer compound (P) is in the range of 50 ppm to 200 ppm compared to when the content is 15 ppm.

[0162] The reason why lead-acid batteries with a pull-out load ratio of 1.5 or more and a polymer compound (P) content of 15 ppm or more and 400 ppm or less have such high characteristics is not clear at present, but the following speculation is possible.

[0163] (One guess as to why it works) The polymer compound (P) is thought to thinly coat the surface of the negative electrode active material. Therefore, the polymer compound (P) is thought to suppress the growth of dendrites, which are caused by the deposition of lead ions dissolved from the negative electrode active material on the negative electrode active material. A high pull-out load ratio narrows the plate spacing, generally making permeation short circuits more likely to occur. However, if the negative electrode material contains an appropriate amount of polymer compound (P), dendrite growth is suppressed, thereby preventing permeation short circuits even with a narrow plate spacing. Furthermore, a high pull-out load is thought to suppress the migration of the polymer compound (P), making it more likely to remain in the negative electrode plate. As a result, a high pull-out load may be more effective in suppressing short circuits. Furthermore, a high pull-out load ratio reduces charge transfer resistance due to the narrow plate spacing, improving charge acceptance. A high concentration of polymer compound (P) tends to increase the proportion of the surface of the negative electrode active material covered by the polymer compound (P), resulting in a decrease in charge acceptance. However, when the content of the polymer compound (P) is 400 ppm or less, it is believed that the decrease in charge acceptance can be suppressed by setting the withdrawal load ratio to 1.5 or more. Furthermore, by adding the polymer compound (P) to the negative electrode material, the hydrogen overvoltage at the negative plate can be increased, thereby suppressing the overcharge quantity of electricity. As a result, the decrease in electrolyte can be suppressed. The above reasons may be the reason why the lead-acid battery of the present invention achieves a good balance between a small overcharge quantity of electricity, high charge acceptance, and a low incidence of permeation short circuits.

[0164] Example 2 In Example 2, several types of lead-acid batteries were fabricated under the same conditions as the lead-acid battery A24 of Example 1 (see Table 1), except that the number-average molecular weight Mn of polypropylene glycol (PPG, polymer compound (P)) was changed. These several types of lead-acid batteries were evaluated in the same manner as in Example 1. Table 3 shows some of the fabrication conditions and evaluation results for these lead-acid batteries. Note that the evaluation of lead-acid battery B3 includes the evaluation of lead-acid battery A24. The meanings of notes (*1) to (*5) in Table 3 are the same as those of notes (*1) to (*5) in Tables 1 and 2, respectively.

[0165] [Table 3]

[0166] As shown in Table 3, when the number-average molecular weight of the polymer compound (P) is in the range of 500 to 5000, a small overcharge quantity of electricity, high charge acceptance, and a low incidence of permeation short circuit can be achieved. When the number-average molecular weight of the polymer compound (P) is in the range of 1000 to 5000, the overcharge quantity of electricity can be particularly reduced.

[0167] Example 3 In Example 3, several types of lead-acid batteries were fabricated under the same conditions as the lead-acid battery A25 of Example 1 (see Table 1), except that the type of polymer compound (P) was changed. These several types of lead-acid batteries were evaluated in the same manner as in Example 1. Table 4 shows some of the fabrication conditions and evaluation results for these lead-acid batteries. Note that the evaluation of lead-acid battery C1 shows the evaluation of lead-acid battery A25. The meanings of notes (*1) to (*5) in Table 4 are the same as those of notes (*1) to (*5) in Tables 1 and 2, respectively. The content of each polymer compound (P) in the negative electrode material was 50 ppm (mass ratio). The number average molecular weight (Mn) of each polymer compound (P) was in the range of 1,800 to 2,000.

[0168] [Table 4]

[0169] The polymer compound (P) of the lead-acid battery C2 is polyethylene glycol (PEG). The polymer compound 1 of the lead-acid battery C3 is polyoxyethylene polyoxypropylene butyl ether. The proportion of oxypropylene units in the total monomer units of this polymer compound 1 is 43 mol%. The polymer compound 2 of the lead-acid battery C4 is polyoxypropylene acetate. All of the polymer compounds used in Example 3 are measured using deuterated chloroform as a solvent. 1In the chemical shift of the H-NMR spectrum, it has a peak in the range of 3.2 ppm to 3.8 ppm.

[0170] As shown in Table 4, even when a polymer compound (P) other than polypropylene glycol (PPG) is used, good results similar to those obtained with PPG can be obtained. [Industrial Applicability]

[0171] The present invention can be used in lead-acid batteries. [Explanation of symbols]

[0172] 1:Lead acid battery 2: Negative electrode plate 3: Positive electrode plate 4: Separator 11: Plate group 12:Battery container 13: Bulkhead 14: Cell Room 15: Lid 16: Negative terminal 17: Positive terminal

Claims

1. A group of electrodes; An electrolyte; a battery case that contains the electrode plate group and the electrolyte; the electrode plate group includes a plurality of stacked positive electrode plates and a plurality of stacked negative electrode plates, the negative electrode plate includes a negative electrode material, the negative electrode material includes a polymer compound; The polymer compound is oxy C ２－４ Contains alkylene units as a repeating structure, the content of the polymer compound in the negative electrode material is 15 ppm or more and 400 ppm or less by mass, a pull-out load when the electrode plate group is pulled out of the battery case is 1.5 times or more the weight of the electrode plate group itself.

2. The polymer compound is ２－４ 2. The lead acid battery according to claim 1, comprising at least one selected from the group consisting of a hydroxy compound containing the repeating structure of an alkylene unit, an etherified product of the hydroxy compound, and an esterified product of the hydroxy compound.

3. 2. The lead-acid battery according to claim 1, wherein the polymer compound is at least one selected from the group consisting of polyethylene glycol, an esterified product of polyethylene glycol, polypropylene glycol, and an esterified product of polypropylene glycol.

4. 4. The lead-acid battery according to claim 3, wherein the polymer compound is polypropylene glycol.

5. The lead acid battery according to any one of claims 1 to 4, wherein the number average molecular weight of the polymer compound is 1000 or more.

6. 6. The lead acid battery according to claim 5, wherein the number average molecular weight of the polymer compound is 5,000 or less.

7. The lead-acid battery according to any one of claims 1 to 6, wherein a pull-out load when pulling out the electrode plate group from the battery case is 10.0 times or less the weight of the electrode plate group.

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