lead-acid batteries

Abstract

This lead acid storage battery is provided with at least one cell that is provided with an electrode plate group and an electrolyte solution. The electrode plate group is provided with a negative electrode plate, a positive electrode plate and a separator that is interposed between the negative electrode plate and the positive electrode plate. The negative electrode plate is provided with a collector that has a lug part, and a negative electrode material. The lug part is provided with a surface layer that contains Sn. The content of Sn in the surface layer is less than 10% by mass. The negative electrode material contains a polymer compound which 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.

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. A lead-acid battery includes a negative electrode plate, a positive electrode plate, a separator (or mat), and an electrolyte. Each electrode plate includes a current collector and an electrode material. The top of the current collector is provided with a tab for connecting to an external terminal.

[0003] Lead-acid batteries are sometimes used in a state of insufficient charge known as partial state of charge (PSOC). For example, lead-acid batteries installed in vehicles with idle stop-start (ISS) systems are used in PSOC. When lead-acid batteries are repeatedly charged and discharged in PSOC, corrosion can cause the thickness of the negative electrode plate to decrease, resulting in reduced battery life. To prevent this corrosion, the application of a surface layer to the battery plate has been considered.

[0004] Patent Document 1 proposes a lead-acid battery comprising a positive electrode plate, a negative electrode plate, and an electrolyte, in which the negative electrode plate comprises a negative electrode current collector having a grid-shaped grid portion, an edge portion connected to the edge of the grid portion, and a current collecting ear portion protruding from the edge portion, and a surface layer containing an alloy or metal selected from a Pb-Sn alloy, a Pb-Sb alloy, a Pb-Sn-Sb alloy, and Sn is formed on the surface of at least one of the edge portion and the ear portion, and the electrolyte contains one or more selected from sodium ions, potassium ions, magnesium ions, aluminum ions, phosphoric acid, and boric acid.

[0005] Furthermore, in order to impart various functions, additives are sometimes added to the components of lead-acid batteries.

[0006] Patent Document 2 proposes a lead acid battery in which a copolymer of propylene oxide and ethylene oxide is added to the negative electrode plate active material in combination with lignin sulfonic acid. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2009 / 142220 [Patent Document 2] Japanese Patent Application Publication No. 182662 / 1983 Summary of the Invention [Problem to be solved by the invention]

[0008] When a lead-acid battery is repeatedly charged and discharged at PSOC, the potential of the lug of the negative electrode plate reaches a range where corrosion easily progresses. Corrosion of the lug causes thinning of the lug, which can lead to breakage, making charging and discharging impossible. Providing a surface layer containing Sn on the lug, as in Patent Document 1, can reduce the corrosion of the lug to some extent. However, to obtain the corrosion-inhibiting effect of the surface layer, the Sn concentration in the surface layer must be as high as 10 mass% or more. [Means for solving the problem]

[0009] One aspect of the present invention is a lead-acid battery, The lead-acid battery includes at least one cell including a plate group and an electrolyte; the electrode plate group includes a negative electrode plate, a positive electrode plate, and a separator interposed between the negative electrode plate and the positive electrode plate, The negative electrode plate includes a current collector having a lug portion and a negative electrode material, the ear portion has a surface layer containing Sn, The Sn content in the surface layer is less than 10 mass %, The negative electrode material is measured using deuterated chloroform as a solvent. 1 The present invention relates to a lead-acid battery containing 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.

[0010] Another aspect of the present invention is a lead-acid battery, The lead-acid battery includes at least one cell including a plate group and an electrolyte; the electrode plate group includes a negative electrode plate, a positive electrode plate, and a separator interposed between the negative electrode plate and the positive electrode plate, The negative electrode plate includes a current collector having a lug portion and a negative electrode material, the ear portion has a surface layer containing Sn, The Sn content in the surface layer is less than 10 mass %, The negative electrode material is oxy C 2-4 The present invention relates to a lead-acid battery comprising a polymer compound containing a repeating structure of alkylene units. [Brief explanation of the drawings]

[0011] [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. [Figure 2] 10 is a graph showing changes in terminal voltage of lead-acid batteries E17 to E19 in the PSOC cycle. [Figure 3] 10 is a graph showing changes in potential at the lug of the negative electrode plate in the PSOC cycle of lead-acid batteries E17 to E19. [Figure 4] 10 is a graph showing changes in the specific gravity of the electrolyte at the top of the electrode plate group during PSOC cycles of lead-acid batteries E17 to E19. [Figure 5] 10 is a graph showing the relationship between the specific gravity of the electrolyte and the amount of thinning of the edge of the negative electrode plate of lead-acid batteries E20 to E23 and E24 to E27. [Figure 6] FIG. 4 is an explanatory diagram of measurement points for the thickness of the electrode plate. DETAILED DESCRIPTION OF THE INVENTION

[0012] When lead-acid batteries are repeatedly charged and discharged in the PSOC cycle, corrosion progresses at the lug of the negative plate, which can cause thinning of the lug. During the PSOC cycle, the potential of the lug of the negative plate falls into a range where lead sulfate is easily produced from lead during discharge, and where the reduction of lead sulfate to lead is incomplete during charge. It is thought that this repetition gradually progresses corrosion inside the lug, causing thinning of the lug.

[0013] At the potential of the negative electrode lug during the PSOC cycle, oxidation and reduction reactions of Sn are unlikely to occur. Therefore, if a Sn-containing surface layer is provided on the lug of a negative electrode, the shielding effect of Sn makes it difficult for oxidation and reduction reactions involving lead to occur at the lug. As a result, when a Sn-containing surface layer is provided on the lug of a negative electrode, the loss of edge thickness during the PSOC cycle is reduced compared to when no surface layer is provided. Therefore, the greater the Sn content in the surface layer, the less edge thickness there is. On the other hand, a high Sn content is not only cost-inefficient, but also increases the amount of gas generated during overcharge, resulting in a greater loss of electrolyte. From the perspectives of reducing cost and reducing the loss of electrolyte during overcharge, it is advantageous to keep the Sn content of the surface layer low. However, when the Sn content is less than 10% by mass, it has been thought that it is practically difficult to suppress edge thickness during the PSOC cycle using a Sn-containing surface layer.

[0014] However, it has been found that even when the Sn content in the surface layer of the ear of the negative plate is less than 10 mass %, adding a specific polymer compound to the negative electrode material of the negative plate significantly reduces ear thinning when the lead-acid battery is charged and discharged at PSOC.

[0015] In view of the above, a lead-acid battery according to one aspect of the present invention includes at least one cell including an electrode plate assembly and an electrolyte. The electrode plate assembly includes a negative electrode plate, a positive electrode plate, and a separator interposed between the negative electrode plate and the positive electrode plate. The negative electrode plate includes a current collector with a lug portion and a negative electrode material. The lug portion includes a surface layer containing Sn. The Sn content in the surface layer is less than 10 mass %. The negative electrode material is measured using deuterated chloroform as a solvent.1 The polymer compounds include those having a peak in the range of 3.2 ppm to 3.8 ppm in the chemical shift of the H-NMR spectrum. In addition, the above 1 In the H-NMR spectrum, the peaks appearing in the chemical shift range of 3.2 ppm to 3.8 ppm are oxy-C 2-4 It is derived from an alkylene unit.

[0016] A lead-acid battery according to another aspect of the present invention includes at least one cell including an electrode plate assembly and an electrolyte. The electrode plate assembly includes a negative electrode plate, a positive electrode plate, and a separator interposed between the negative electrode plate and the positive electrode plate. The negative electrode plate includes a current collector with a lug portion and a negative electrode material. The lug portion includes a surface layer containing Sn. The Sn content in the surface layer is less than 10 mass %. The negative electrode material is oxy-C. 2-4 It includes polymeric compounds containing repeating alkylene units.

[0017] In the lead-acid batteries according to one and other aspects of the present invention, the negative electrode material contains the polymer compound described above. Combining this negative electrode material with a negative electrode current collector having a surface layer containing Sn in the edge portion can reduce edge thinning during PSOC cycles, even when the Sn content in the surface layer is less than 10% by mass. In addition to the lower Sn content in the surface layer compared to conventional negative electrode materials, the inclusion of a polymer compound in the negative electrode material suppresses gas generation during overcharge, thereby reducing electrolyte loss (hereinafter sometimes simply referred to as electrolyte loss). In other words, this achieves both an excellent effect of reducing edge thinning during PSOC cycles and an excellent effect of reducing electrolyte loss during overcharge. Suppressing edge thinning can prevent edge thinning from causing breakage of the edge portion, which can prevent charging and discharging from becoming impossible. Therefore, even when the Sn content in the surface layer is less than 10% by mass, the lead-acid battery can be actually used. This is advantageous in terms of extending the life of the lead-acid battery. Furthermore, the ability to reduce the Sn content in the surface layer is advantageous in terms of cost reduction.

[0018] The following is thought to be the reason why the inclusion of the above-mentioned polymer compound in the negative electrode material reduces edge thinning in the negative electrode plate during PSOC cycling. First, the inclusion of the above-mentioned polymer compound in the negative electrode material results in the presence of the polymer compound in the vicinity of the lead, which is the negative electrode active material. This causes the potential of the negative electrode plate to shift in a more base-pole direction during PSOC cycling. The potential of the lug of the negative electrode plate also shifts in a more base-pole direction, facilitating the reduction reaction of lead sulfate to lead during charging. In addition to the shielding effect of Sn in the lug, lead sulfate is less likely to accumulate, which reduces edge thinning even though the Sn content in the surface layer is as low as less than 10% by mass.

[0019] Furthermore, the low Sn content in the surface layer is thought to suppress the gas generation reaction involving Sn during overcharge. In addition, the potential of the negative electrode plate shifts in a less noble direction, increasing the hydrogen overvoltage, thereby suppressing the generation of hydrogen gas at the negative electrode plate during overcharge. In this way, suppressing gas generation during overcharge can reduce the loss of electrolyte.

[0020] The effect of suppressing edge thinning in the negative electrode plate during PSOC cycles and the effect of suppressing electrolyte loss during overcharge can be obtained even when the content of the polymer compound in the negative electrode material is very small (for example, less than 0.01 mass %). 2-4 It is believed that the alkylene unit exerts a high adsorption effect on lead. Furthermore, it is believed that the polymer compound spreads thinly on the surface of the lead, which facilitates a shift in the potential of the entire negative electrode plate, including the lug portion, toward a more base-containing direction. It is also believed that the polymer compound spreads thinly on the surface of the lead, which increases the hydrogen overvoltage over a wide area of ​​the lead surface of the negative electrode plate and inhibits the side reaction of generating hydrogen by the reduction of protons during overcharge. The fact that the polymer compound spreads thinly on the surface of the lead is consistent with the polymer compound's tendency to form a linear structure. Therefore, it is important that the polymer compound is contained in the negative electrode material, regardless of whether it is contained in components of the lead-acid battery other than the negative electrode material.

[0021] In the lead-acid battery according to one aspect of the present invention, the polymer compound may include oxygen atoms bonded to end groups and -CH2- groups and / or -CH< groups bonded to the oxygen atoms. 1 In the H-NMR spectrum, the ratio of the integral value of the peaks between 3.2 ppm and 3.8 ppm to the total integral value of the peaks between 3.2 ppm and 3.8 ppm, the integral value of the peaks of the hydrogen atoms of the -CH2- groups bonded to the oxygen atoms, and the integral value of the peaks of the hydrogen atoms of the -CH< groups bonded to the oxygen atoms is preferably 85% or more. 2-4 The polymer compound contains many alkylene units in its molecule. This makes it easier for the polymer compound to adsorb to lead, and its linear structure makes it easier to thinly coat the lead surface. This further reduces the edge thinning of the negative electrode plate during PSOC cycles and further improves the effectiveness of suppressing electrolyte loss during overcharge.

[0022] 1 Polymer compounds with peaks in the chemical shift range of 3.2 ppm to 3.8 ppm in the H-NMR spectrum are oxy-C 2-4 It is preferable that the alkylene unit contains a repeating structure. 2-4 When a polymer compound containing a repeating alkylene unit structure is used, it is believed that the polymer compound is more easily adsorbed to lead and that its linear structure makes it easier to thinly coat the lead surface, which is advantageous in further suppressing the thinning of the negative electrode plate during PSOC cycles and the loss of electrolyte during overcharge.

[0023] The polymer compound is OxyC 2-4 The hydroxy compound may contain at least one selected from the group consisting of a hydroxy compound having a repeating structure of an alkylene unit, an etherified product of a hydroxy compound, and an esterified product of a hydroxy compound. 2-4 Alkylene glycol, oxy C 2-4 Copolymers containing repeating alkylene units and polyol polyC2-4 The polymer compound is at least one selected from the group consisting of alkylene oxide adducts. When such a polymer compound is used, it is possible to further suppress the thinning of the edge of the negative electrode plate during PSOC cycles and the loss of electrolyte during overcharge.

[0024] Oxy C 2-4 The repeating structure of the alkylene unit may include at least a repeating structure of an oxypropylene unit (-O-CH(-CH3)-CH2-). Such a polymer compound is thought to have an excellent balance of high adsorption to lead while easily spreading thinly over the lead surface. This can more effectively reduce loss of electrolyte. It can also further reduce thinning of the negative electrode plate.

[0025] Thus, because the polymer compound has high adsorption properties for lead while also being able to thinly coat the lead surface, even a very small amount of polymer compound (more specifically, 400 ppm or less) in the negative electrode material can reduce edge thinning of the negative electrode plate during PSOC cycles and electrolyte loss during overcharge. From the perspective of ensuring a higher effect of suppressing edge thinning and electrolyte loss, the content of the polymer compound in the negative electrode material is preferably 15 ppm or more.

[0026] The origin of the polymer compound contained in the negative electrode material is not particularly limited as long as the polymer compound can be contained in the negative electrode material. When producing a lead-acid battery, the polymer compound 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).

[0027] The Sn content in the surface layer of the edge portion is preferably 7 mass % or less. Even when the Sn content is this low, the effect of the polymer compound can reduce edge thinning and liquid loss.

[0028] The Sn content in the surface layer of the edge portion is preferably 0.01% by mass or more. In this case, the effect of suppressing edge thinning due to Sn can be obtained. Furthermore, even with such a low Sn content, the action of the polymer compound can ensure a high effect in reducing edge thinning and liquid loss.

[0029] In at least one of the cells, the electrode plate assembly preferably includes a plurality of positive electrode plates and a plurality of negative electrode plates, and the positive electrode plates and the negative electrode plates are alternately stacked with separators interposed therebetween, and the electrode plate assembly preferably includes nine or more negative electrode plates. Increasing the number of electrode plates included in the electrode plate assembly prevents a decrease in the specific gravity of the electrolyte in the upper part of the electrode plate assembly. This prevents lead dissolution, further enhancing the effect of preventing edge thinning of the negative electrode plates.

[0030] It is preferable that the relationship between the distance between the positive and negative plates in the electrode plate assembly (inter-electrode distance D) and the maximum separator thickness T be DT≦0.15 mm or less. When the relationship between the inter-electrode distance D and the maximum separator thickness T is in this range, the effect of suppressing the decrease in the specific gravity of the electrolyte in the upper part of the electrode plate assembly is further enhanced. Since the decrease in the specific gravity of the electrolyte around the edge portion is further suppressed, the effect of suppressing edge thinning of the negative plate is further enhanced.

[0031] The electrolyte preferably contains Al ions, which suppresses the accumulation of lead sulfate during PSOC cycles, thereby further suppressing the decrease in the specific gravity of the electrolyte around the edge of the negative electrode plate, thereby further suppressing edge thinning of the negative electrode plate.

[0032] The lead acid battery may be either a valve regulated (sealed) lead acid battery (VRLA type lead acid battery) or a flooded (vented) lead acid battery.

[0033] In this specification, the Sn content in the surface layer of the lug portion of the negative electrode plate, the polymer compound content in the negative electrode material, the inter-electrode distance D, and the maximum thickness T of the separator are determined for a negative electrode plate, an electrode plate group, or a separator removed from a fully charged lead-acid battery.

[0034] (Terminology explanation) (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 its components (such as plates, a battery case, and a separator) refers to the up-down direction in the vertical direction of the lead-acid battery when the battery is in use. Each of the positive and negative plates has a lug for connecting to an external terminal. In some cases, such as horizontally placed valve-regulated lead-acid batteries, the lug is provided on the side of the plate so as to protrude laterally, but in most lead-acid batteries, the lug is usually provided on the top of the plate so as to protrude upward.

[0035] (surface layer of ear part) When the cross section of the ear of the negative electrode plate or negative electrode current collector is observed with a metallurgical microscope, the outer layer that has different properties (color, state of metal particles, etc.) from the inner layer is called the surface layer.

[0036] (Negative electrode material) The negative electrode material is usually held by a 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 (such as a mat or pasting paper), the negative electrode material is the portion of the negative electrode plate excluding the current collector and attachment member.

[0037] (polymer compound) The polymer compound satisfies at least one of the following conditions (i) and (ii): Condition (i) Polymer compounds are 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. Condition (ii) The polymer compound is OxyC 2-4 It contains a repeating structure of alkylene units.

[0038] Under condition (i), the peak in the range of 3.2 ppm to 3.8 ppm is oxy-C. 2-4 The polymer compounds satisfying the condition (ii) are derived from alkylene units. In other words, the polymer compounds satisfying the condition (i) are also polymer compounds satisfying the condition (i). The polymer compounds satisfying the condition (i) are derived from oxy C 2-4 The polymer compound 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 a polymer compound satisfying the above (i) or (ii) may be, for example, 300 or more.

[0039] (Oxy C 2-4 alkylene unit) Oxy C 2-4 The alkylene unit is -OR 1 -(R 1 is C 2-4 It is a unit represented by the formula (1).

[0040] (number average molecular weight) In this specification, the number average molecular weight (Mn) is determined by gel permeation chromatography (GPC). The standard substance used to determine Mn is polyethylene glycol.

[0041] (distance between poles D) The inter-electrode distance D is expressed by the following formula. Distance between electrodes D = (pitch - thickness of positive electrode plate - thickness of negative electrode plate) / 2 Here, the pitch is the average value of the center-to-center distance between the lugs of a pair of adjacent positive plates. More specifically, the pitch is the average value of the center-to-center distance between the lugs of all pairs of adjacent positive plates included in the plate group. In a lead-acid battery having multiple series-connected plate groups, the pitch is the average value for one plate group (cell) located at the end and one plate group (cell) located near the center. Furthermore, the thickness of a positive plate is the average value of the thicknesses of all positive plates included in the plate group, and the thickness of a negative plate is the average value of the thicknesses of all negative plates included in the plate group.

[0042] (Maximum separator thickness T) The maximum separator thickness T is the average value of the maximum separator thicknesses t of all separators included in a plate group (cell). In a lead-acid battery having multiple plate groups connected in series, the maximum separator thickness T is the average value of the thicknesses t of one plate group (cell) located at the end and one plate group (cell) located near the center.

[0043] If the thickness of the separator differs between the peripheral edge and the portion inside the peripheral edge, the maximum thickness t is measured for the portion inside the peripheral edge. If the separator has a base portion and ribs protruding from at least one main surface of the base portion, the thickness of the separator includes the thickness of the base portion and the ribs. For example, if ribs are formed on both sides of the separator, the thickness of the separator is the sum of the thickness of the base portion, the height of the ribs from the base portion on one main surface, and the height of the ribs from the base portion on the other main surface. The thickness of the separator where this sum is greatest is the maximum thickness t.

[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 at a current (A) 0.2 times the rated capacity (unit: Ah) until the terminal voltage (V) during charging or the electrolyte density converted to a temperature of 20°C, measured every 15 minutes, shows a constant value to three significant digits for three consecutive measurements. For a valve-regulated lead-acid battery, the fully charged state is defined as a state in which charging is terminated when the charging current during constant voltage charging reaches 0.005 times the rated capacity (unit: Ah) in an air tank at 25°C, at a constant current / constant voltage of 2.23 V / cell.

[0045] A fully charged lead-acid battery refers to a lead-acid battery that has already been chemically formed and is fully charged. A lead-acid battery can be fully charged immediately after chemical formation, or after some time has passed since chemical formation (for example, a lead-acid battery that has been in use (preferably in the early stages of use) after chemical 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] Hereinafter, the lead-acid battery according to the embodiment of the present invention will be described in detail for each of its main components, but the present invention is not limited to the following embodiment.

[0047] [Lead acid battery] (negative plate) The negative electrode plate includes a current collector (negative electrode current collector) with a lug portion and a negative electrode material.

[0048] (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. A lattice-shaped current collector is preferably used as the negative electrode current collector because it is easy to support the negative electrode material.

[0049] The lead alloy used for the negative electrode current collector may be any of a Pb-Ca alloy, a Pb-Ca-Sn alloy, and a Pb-Sn alloy. These lead or lead alloys may further contain at least one additive element selected from the group consisting of Ba, Ag, Al, Bi, As, Se, and Cu.

[0050] The negative electrode current collector has a surface layer at least on the edge portion. The surface layer of the edge portion contains Sn. The surface layer contains, for example, a lead alloy containing Sn. Such a surface layer can suppress edge thinning during PSOC cycling.

[0051] The Sn content in the surface layer of the ear portion is less than 10% by mass, and may be 7% by mass or less, 6% by mass or less, or 5% by mass or less. The Sn content in the surface layer is, for example, 0.01% by mass or more, 0.05% by mass or more, or 0.1% by mass or more. Even with such a low Sn content in the surface layer, ear thinning can be reduced by combining it with a negative electrode material containing a polymer compound. Furthermore, the low Sn content also reduces the effect of reducing liquid loss.

[0052] The Sn content in the surface layer of the ear portion may be 0.01% by mass or more and less than 10% by mass (or 7% by mass or less), 0.05% by mass or more and less than 10% by mass (or 7% by mass or less), 0.1% by mass or more and less than 10% by mass (or 7% by mass or less), 0.01% by mass or more and 6% by mass or less (or 5% by mass or less), 0.05% by mass or more and 6% by mass or less (or 5% by mass or less), or 0.1% by mass or more and 6% by mass or less (or 5% by mass or less).

[0053] The thickness of the surface layer of the ear portion is, for example, 0.01 mm or more, and may be 0.015 mm or more, or 0.02 mm or more. The thickness of the surface layer is, for example, 0.1 mm or less, and may be 0.05 mm or less.

[0054] The thickness of the surface layer of the ear portion may be 0.01 mm or more and 0.1 mm or less (or 0.05 mm or less), 0.015 mm or more and 0.1 mm or less (or 0.05 mm or less), or 0.02 mm or more and 0.1 mm or less (or 0.05 mm or less).

[0055] (surface layer analysis) The method for measuring the Sn content in the surface layer and the thickness of the surface layer is described below. The measurement is carried out on a negative electrode plate that has been removed from a lead-acid battery, washed with water, and dried under reduced pressure.

[0056] (1) Measurement of Sn content in the surface layer First, the edge of the negative electrode plate is cut along the thickness direction, and the cut surface is observed using a metallurgical microscope. The outer layer, which has different properties from the inner layer, is taken as the surface layer, and a portion of it is scraped off to obtain a sample, and its mass is measured. An Olympus GX53F metallurgical microscope is used.

[0057] The Sn content in the surface layer is analyzed in accordance with lead separation inductively coupled plasma atomic emission spectroscopy as specified in JIS H2105:1955. More specifically, the collected sample is mixed with tartaric acid and dilute nitric acid to obtain an aqueous solution. Hydrochloric acid is added to the aqueous solution to precipitate lead chloride, which is then filtered and the filtrate is collected. The Sn concentration in the filtrate is analyzed using an ICP atomic emission spectrometer with a calibration curve method, and the Sn content in the surface layer of the edge is determined from this Sn concentration and the mass of the collected sample. The ICP atomic emission spectrometer used is an ICPS-8000 manufactured by Shimadzu Corporation.

[0058] (2) Thickness of the surface layer The ears of the negative electrode plate are impregnated with epoxy resin and allowed to harden. The ears are then cut along the thickness direction of the ears, and the cut surface is polished. The polished cut surface is observed with a metallurgical microscope, and the outer layer, which has different properties from the inner layer, is considered the surface layer. The thickness is measured at any five points and averaged to determine the thickness of the surface layer. An Olympus GX53F metallurgical microscope is used.

[0059] (Negative electrode material) The negative electrode material includes the polymer compound. 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.

[0060] (polymer compound) The polymer compound is 1 In the chemical shift of the H-NMR spectrum, the peak is in the range of 3.2 ppm to 3.8 ppm. 2-4 Contains alkylene units. OxyC 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. 2-4 The alkylene unit may have one type or two or more types.

[0061] The polymer compound is OxyC 2-4 It is preferred that the repeating unit contains a repeating alkylene unit. 2-4 may contain alkylene units, and two or more oxy C 2-4 The polymer compound may contain one type of repeating structure or two or more types of repeating structures.

[0062] Oxy C 2-4 Polymer compounds having a repeating structure of alkylene units also include polymer compounds classified as surfactants (more specifically, nonionic surfactants).

[0063] Examples of polymer compounds include oxy C 2-4 Hydroxy compounds with repeating alkylene units (polyC 2-4 Alkylene glycol, oxy C 2-4 Copolymer containing repeating alkylene units, polyol polyC 2-4 alkylene oxide adducts, ethers or esters of these hydroxy compounds, etc.

[0064] As copolymers, different oxy C 2-4The copolymer may be a block copolymer.

[0065] 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) 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). 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, or sorbitol. The sugar or sugar alcohol may have either a linear structure or a cyclic structure. In the polyalkylene 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.

[0066] 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.

[0067] The esterified 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 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.

[0068] 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.

[0069] 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., bisC6-10 Aryl C 1-4 Alkanes (such as 2,2-bisphenylpropane) are examples.

[0070] 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.

[0071] 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.

[0072] Examples of alicyclic hydrocarbon groups include cycloalkyl groups (cyclopentyl, cyclohexyl, cyclooctyl, etc.) and cycloalkenyl groups (cyclohexenyl, cyclooctenyl, etc.). Alicyclic hydrocarbon groups also include hydrogenated products of the above aromatic hydrocarbon groups.

[0073] Among hydrocarbon groups, aliphatic hydrocarbon groups are preferred from the viewpoint of facilitating thin adhesion of the polymer compound to the lead surface. The aliphatic hydrocarbon group may be saturated or unsaturated. Examples of the aliphatic hydrocarbon group include an alkyl group, an alkenyl group, an alkynyl group, a dienyl group having two carbon-carbon double bonds, and a trienyl group having three carbon-carbon double bonds. The aliphatic hydrocarbon group may be either linear or branched.

[0074] 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, 3 or more for dienyl groups, and 4 or more for trienyl groups. Among these, alkyl and alkenyl groups are preferred from the viewpoint of facilitating thin adhesion of the polymer compound to the lead surface.

[0075] Specific examples of alkyl groups include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl, neopentyl, i-pentyl, s-pentyl, 3-pentyl, t-pentyl, n-hexyl, 2-ethylhexyl, n-octyl, n-nonyl, n-decyl, i-decyl, undecyl, lauryl (dodecyl), tridecyl, myristyl, pentadecyl, cetyl, heptadecyl, stearyl, icosyl, heneicosyl, and behenyl.

[0076] Specific examples of the alkenyl group include vinyl, 1-propenyl, allyl, cis-9-heptadecen-1-yl, palmitoleyl, and oleyl. 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.

[0077] Among polymer compounds, oxy C 2-4 Ethers of hydroxy compounds with repeating alkylene units and oxy-C 2-4The 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 can further enhance the effect of reducing ear thinning of the negative electrode plate. Furthermore, even when these polymer compounds are used, a high effect of suppressing liquid loss can be ensured. Among these polymer compounds, polymer compounds having a repeating oxypropylene unit structure or a repeating oxyethylene unit structure are preferred.

[0078] The polymer compound may have one or more hydrophobic groups. Examples of the hydrophobic group include, among the above-mentioned hydrocarbon groups, aromatic hydrocarbon groups, alicyclic hydrocarbon groups, and long-chain aliphatic hydrocarbon groups. Examples of the long-chain aliphatic hydrocarbon group include, among the above-mentioned aliphatic hydrocarbon groups (such as alkyl groups and alkenyl groups), aliphatic hydrocarbon groups having 8 or more carbon atoms. The aliphatic hydrocarbon group preferably has 12 or more carbon atoms, more preferably 16 or more carbon atoms. Among these, polymer compounds having long-chain aliphatic hydrocarbon groups are preferred because they are less likely to excessively adsorb lead and can further reduce ear thinning. The polymer compound may be a polymer compound in which at least one of the hydrophobic groups is a long-chain aliphatic hydrocarbon group. The long-chain aliphatic hydrocarbon group may have 30 or less, 26 or less, or 22 or less carbon atoms.

[0079] The long-chain aliphatic hydrocarbon group may have 8 or more (or 12 or more) and 30 or less, 8 or more (or 12 or more) and 26 or less, 8 or more (or 12 or more) and 22 or less, 10 or more and 30 or less (or 26 or less), or 10 or more and 22 or less carbon atoms.

[0080] Among polymer compounds, polymer compounds having both hydrophilic and hydrophobic groups correspond to nonionic surfactants. The repeating structure of oxyethylene units exhibits high hydrophilicity and can serve as the hydrophilic group in nonionic surfactants. Therefore, it is preferable that the polymer compound having the hydrophobic group contains a repeating structure of oxyethylene units. Such polymer compounds selectively adsorb lead while suppressing excessive coverage of the lead surface due to the balance between hydrophobicity and high hydrophilicity resulting from the repeating structure of oxyethylene units, thereby further reducing ear thinning while reducing solution loss. Such polymer compounds can ensure high adsorption to lead even with a relatively low molecular weight (e.g., Mn of 1000 or less).

[0081] Among the above polymer compounds, polyoxypropylene-polyoxyethylene block copolymers, etherified products of hydroxy compounds having a repeating structure of oxyethylene units, and esterified products of hydroxy compounds having a repeating structure of oxyethylene units correspond to nonionic surfactants.

[0082] In polyoxypropylene-polyoxyethylene block copolymers, the repeating structure of oxyethylene units corresponds to the hydrophilic group, and the repeating structure of oxypropylene units corresponds to the hydrophobic group. Such copolymers are also included in polymer compounds having hydrophobic groups.

[0083] Examples of polymer compounds having a hydrophobic group and a repeating structure of oxyethylene units include etherified polyethylene glycol (e.g., alkyl ethers), esterified polyethylene glycol (e.g., carboxylic acid esters), etherified polyethylene oxide adducts of the above polyols (e.g., alkyl ethers), and esterified polyethylene oxide adducts of the above polyols (e.g., triols or higher polyols) (e.g., carboxylic acid esters). Specific examples of such polymer compounds include polyethylene glycol oleate, polyethylene glycol dioleate, polyethylene glycol dilaurate, polyethylene glycol distearate, polyoxyethylene coconut oil fatty acid sorbitan, polyoxyethylene sorbitan oleate, polyoxyethylene sorbitan stearate, polyoxyethylene lauryl ether, polyoxyethylene tetradecyl ether, and polyoxyethylene cetyl ether. However, the polymer compounds are not limited to these. Among these, the use of esterified polyethylene glycol and esterified polyethylene oxide adducts of the above polyols is preferred because they can further reduce ear thinning and significantly reduce fluid loss.

[0084] In order to further enhance the effect of reducing ear thinning of the negative electrode plate and the effect of reducing the loss of electrolyte, Oxy C 2-4 It is also preferable that the repeating alkylene unit contains at least a repeating oxypropylene unit. 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 1In 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-.

[0085] Examples of polymer compounds containing at least a repeating structure of oxypropylene units include polypropylene glycol, copolymers containing a repeating structure of oxypropylene units, polypropylene 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 the oxypropylene-oxyalkylene copolymer include an oxypropylene-oxyethylene copolymer and an oxypropylene-oxytrimethylene copolymer. The oxypropylene-oxyalkylene copolymer is sometimes referred to as a polyoxypropylene-polyoxyalkylene copolymer (e.g., a polyoxypropylene-polyoxyethylene copolymer). The oxypropylene-oxyalkylene copolymer may be a block copolymer (e.g., a polyoxypropylene-polyoxyethylene block copolymer). Examples of the etherified products include polypropylene glycol alkyl ethers and alkyl ethers of oxypropylene-oxyalkylene copolymers (e.g., alkyl ethers of polyoxypropylene-polyoxyethylene copolymers). Examples of the esterified products include polypropylene glycol esters of carboxylic acids and carboxylic acid esters of oxypropylene-oxyalkylene copolymers (e.g., carboxylic acid esters of polyoxypropylene-polyoxyethylene copolymers).

[0086] Examples of polymer compounds containing at least a repeating structure of oxypropylene units include polypropylene glycol, polyoxypropylene-polyoxyethylene copolymers (such as polyoxypropylene-polyoxyethylene block copolymers), polypropylene glycol alkyl ethers (such as the above-mentioned R 2 alkyl ethers (methyl ether, ethyl ether, butyl ether, etc.) in which R is an alkyl having 10 or less carbon atoms (or 8 or less or 6 or less) that may have a substituent, etc.), polyoxyethylene-polyoxypropylene alkyl ethers (the above R 2 alkyl ethers (butyl ether, hydroxyhexyl ether, etc.) in which the alkyl having 10 or less carbon atoms (or 8 or less or 6 or less) may have a substituent, etc.), polypropylene glycol carboxylate (the above R 3 Examples of the polymer compound include polypropylene glycol carboxylates (such as polypropylene glycol acetate) in which the alkyl group has 10 or less carbon atoms (or 8 or less, or 6 or less), and polypropylene oxide adducts of triol or higher polyols (such as polypropylene oxide adducts of glycerin). However, the polymer compound is not limited to these.

[0087] In a polymer compound containing a repeating structure of oxypropylene units, the proportion of oxypropylene units is, for example, 5 mol% or more, or may be 10 mol% or more, or 20 mol% or more. The proportion of oxypropylene units is, for example, 100 mol% or less. In the copolymer, the proportion of oxypropylene units may be 90 mol% or less, 75 mol% or less, 60 mol% or less, or 50 mol% or less, or 43 mol% or less.

[0088] In a polymer compound containing a repeating structure of oxypropylene units, the proportion of oxypropylene units may be 5 mol% to 100 mol% (or 90 mol% or less), 10 mol% to 100 mol% (or 90 mol% or less), 20 mol% to 100 mol% (or 90 mol% or less), 5 mol% to 75 mol% (or 60 mol% or less), 10 mol% to 75 mol% (or 60 mol% or less), 20 mol% to 75 mol% (or 60 mol% or less), 5 mol% to 50 mol% (or 43 mol% or less), 10 mol% to 50 mol% (or 43 mol% or less), or 20 mol% to 50 mol% (or 43 mol% or less).

[0089] The polymer compound is preferably oxy-C, because it increases the adsorption of the polymer compound to lead and makes it easier for the polymer compound to take on a linear structure. 2-4 It is preferable that the polymer compound contains many 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. 1 In the H-NMR spectrum, the integral of the peak between 3.2 ppm and 3.8 ppm accounts for a large proportion of the total integral of this peak, the integral of the peak of the hydrogen atom of the -CH2- group, and the integral of the peak of the hydrogen atom of the -CH< group. This proportion is, for example, 50% or more, and may be 80% or more. From the viewpoint of further enhancing the effect of reducing thinning of the edge of the negative electrode plate and further enhancing the effect of reducing liquid loss, the above proportion is preferably 85% or more, and more preferably 90% or more. For example, when the polymer compound has an -OH group at its terminal and has a -CH2- group and / 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 the -CH< group have chemical shifts in the range of more than 3.8 ppm to 4.0 ppm.

[0090] The negative electrode material may contain one type of polymer compound or two or more types of polymer compounds.

[0091] The polymer compound may include a compound having an Mn of 300 or more, 400 or more, 500 or more, 600 or more, or 1,000 or more. The Mn of such a compound is, for example, 5 million or less, 1 million or less, 100,000 or less, 50,000 or less, 20,000 or less, or 15,000 or less, 10,000 or less. From the viewpoint of facilitating retention of the compound in the negative electrode material and spreading more thinly over the lead surface, the Mn of the compound is preferably 5,000 or less, and may be 4,000 or less, or 3,000 or less. Two or more compounds having different Mn may be used as the polymer compound. In other words, the polymer compound may have multiple Mn peaks in the molecular weight distribution.

[0092] The Mn of the above compounds is 300 to 5 million (or 1 million or less), 400 to 5 million (or 1 million or less), 500 to 5 million (or 1 million or less), 600 to 5 million (or 1 million or less), 1,000 to 5 million (or 1 million or less), 300 to 100,000 (or 50,000 or less), 400 to 100,000 (or 50,000 or less), 500 to 100,000 (or 50,000 or less), 600 to 100,000 (or 50,000 or less), 1,000 to 100,000 (or 50,000 or less), 300 to 20,000 (or 15,000 or less), 300 to 10,000 (or 5,000 or less), 300 to 4,000 ( or 3000 or less), 400 or more and 20,000 or less (or 15,000 or less), 400 or more and 10,000 or less (or 5,000 or less), 400 or more and 4,000 or less (or 3,000 or less), 500 or more (or 600 or more) and 20,000 or less, 500 or more (or 600 or more) and 15,000 or less, 500 or more (or 600 or more) and 10,000 or less, 500 or more (or 600 or more) and 5,000 or less, 500 or more (or 600 or more) and 4,000 or less, 500 or more (or 600 or more) and 3,000 or less, 1,000 or more and 20,000 or less (or 15,000 or less), 1,000 or more and 10,000 or less (or 5,000 or less), or 1,000 or more and 4,000 or less (or 3,000 or less).

[0093] The polymer compound preferably contains a compound with an Mn of 1,000 or greater. The Mn of such a compound may be 1,000 to 50,000, 1,000 to 20,000, 1,000 to 15,000, or 1,000 to 10,000. From the viewpoint of facilitating retention of the compound in the negative electrode material and spreading it more thinly over the lead surface, the Mn of the compound is preferably 1,000 to 5,000, 1,000 to 4,000, or 1,000 to 3,000. The use of such a Mn-containing compound can further enhance the effect of reducing liquid loss. Furthermore, by reducing gas generation during overcharge, structural changes in the negative electrode active material caused by collision of hydrogen gas with the negative electrode active material can be suppressed. Even when contained in the electrolyte, such Mn-containing compounds readily migrate into the negative electrode material, allowing the compound to be replenished in the negative electrode material. From this viewpoint, the compound can be easily retained in the negative electrode material. The polymer compound may be two or more compounds having different Mn, that is, the polymer compound may have multiple Mn peaks in the molecular weight distribution.

[0094] The content of the polymer compound in the negative electrode material is, for example, 8 ppm or more, and may be 10 ppm or more, by mass. From the viewpoint of further improving the effect of reducing ear thinning, the content of the polymer compound in the negative electrode material is preferably 15 ppm or more, by mass. When the content of the polymer compound is within this range, it is easier to increase the hydrogen generating voltage and the effect of suppressing liquid loss can be further improved. The content of the polymer compound (by mass) in the negative electrode material may be, for example, 400 ppm or less, 380 ppm or less, or 370 ppm or less.

[0095] The content of the polymer compound (by mass) may be 8 ppm or more (or 10 ppm or more) and 400 ppm or less, 8 ppm or more (or 10 ppm or more) and 380 ppm or less, 8 ppm or more (or 10 ppm or more) and 370 ppm or less, 15 ppm or more and 400 ppm or less (or 380 ppm or less), or 15 ppm or more and 370 ppm or less.

[0096] (organic shrinkage preventer) The negative electrode material may contain an organic shrinkage inhibitor. 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, sulfonic acid groups or sulfonyl groups, which are stable, are 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.

[0097] As the organic shrink-preventing agent, it is preferable to use 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 condensates thereof). The organic shrink-preventing agent may contain one type of aromatic compound unit, or may contain two or more types of aromatic compound units. The aromatic compound unit refers to a unit derived from an aromatic compound incorporated into the condensation product.

[0098] Examples of aromatic rings contained in aromatic compounds include benzene rings and naphthalene rings. When an aromatic compound has multiple aromatic rings, the multiple aromatic rings may be linked by a direct bond or a linking group (e.g., an alkylene group (including an alkylidene group), a sulfone group), or the like. Examples of such structures include bisarene structures (biphenyl, bisphenylalkane, bisphenylsulfone, etc.). Examples of aromatic compounds include compounds having the above-mentioned aromatic rings and at least one selected from the group consisting of a hydroxy group and an amino group. The hydroxy group or amino group may be directly bonded to the aromatic ring, or may be bonded as an alkyl chain having a hydroxy group or an amino group. The hydroxy group also includes salts of the hydroxy group (-OMe). The amino group also includes salts of the amino group (specifically, salts with an anion). Examples of Me include alkali metals (e.g., Li, K, Na), and metals of Group 2 of the periodic table (e.g., Ca, Mg).

[0099] Preferred aromatic compounds include bisarene compounds (bisphenol compounds, hydroxybiphenyl compounds, bisarene compounds having an amino group (such as bisarylalkane compounds having an amino group, bisarylsulfone compounds having an amino group, and biphenyl compounds having an amino group), hydroxyarene compounds (such as hydroxynaphthalene compounds and phenol compounds), and aminoarene compounds (such as aminonaphthalene compounds and aniline compounds (such as aminobenzenesulfonic acid and alkylaminobenzenesulfonic acid)). The aromatic compounds may further have a substituent. The organic shrink-proofing agent may contain one or more of the residues of these compounds. Preferred bisphenol compounds include bisphenol A, bisphenol S, and bisphenol F.

[0100] The condensate preferably contains at least a unit of an aromatic compound having a sulfur-containing group. In particular, if a condensate containing at least a unit of a bisphenol compound having a sulfur-containing group is used, the effect of suppressing ear thinning can be further enhanced. From the viewpoint of enhancing the effect of suppressing liquid loss, it is preferable to use a condensate of an aldehyde compound with a naphthalene compound having a sulfur-containing group and at least one selected from the group consisting of a hydroxyl group and an amino group.

[0101] The sulfur-containing group may be directly bonded to an aromatic ring contained in the compound, or may be bonded to the aromatic ring as an alkyl chain having a sulfur-containing group. The sulfur-containing group is not particularly limited, and examples thereof include a sulfonyl group, a sulfonic acid group, and salts thereof.

[0102] Furthermore, as the organic shrink-preventing agent, for example, at least one condensate containing at least one selected from the group consisting of the above-mentioned bisarene compound unit and a monocyclic aromatic compound unit (such as a hydroxyarene compound and / or an aminoarene compound) may be used. The organic shrink-preventing agent may also contain at least a condensate containing a bisarene compound unit and a monocyclic aromatic compound unit (especially a hydroxyarene compound). Examples of such condensates include condensates of a bisarene compound and a monocyclic aromatic compound with an aldehyde compound. Preferred hydroxyarene compounds are phenolsulfonic acid compounds (such as phenolsulfonic acid or its substitution products). Preferred aminoarene compounds are aminobenzenesulfonic acid, alkylaminobenzenesulfonic acid, etc. Preferred monocyclic aromatic compounds are hydroxyarene compounds.

[0103] 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.

[0104] 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.

[0105] (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.

[0106] 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.

[0107] 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.

[0108] (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.

[0109] 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.

[0110] (Analysis of the components of negative electrode materials) The following describes a method for analyzing negative electrode materials or their constituents. 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 an adhesive material is contained in the negative electrode plate after drying, the adhesive material is removed by peeling. Next, the negative electrode material is separated from the negative electrode plate and pulverized to obtain a sample (hereinafter referred to as Sample A).

[0111] (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.

[0112] 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.

[0113] 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

[0114] 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 (= V1 / (V1+V2) × 100(%)) is calculated.

[0115] 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.

[0116] (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), 1Measure the H-NMR spectrum. The integral value (S a ) and the integral value of the peak due to TCE (S r ) and calculate the mass-based content C of the polymer compound in the negative electrode material from the following formula: n Calculate the ppm.

[0117] 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.

[0118] For example, if the polymer compound is polypropylene glycol, M a is 58, and N a is 3. If the polymer compound is polyethylene glycol, M a is 44, and N a is 4. In the case of copolymers, N a and M a are the N of each monomer unit, respectively. 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.

[0119] 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.

[0120] (1-3) Mn measurement of polymer compounds Using the above chloroform-soluble fraction, GPC measurement of the polymer compound is carried out using the following apparatus under the following conditions. Separately, a calibration curve (calibration curve) is created 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 of the polymer compound is calculated. However, esterified or etherified products may be in a decomposed state in the chloroform-soluble fraction.

[0121] 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)

[0122] (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-preventing agent. Next, insoluble components are removed from the extract 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-preventing agent (hereinafter referred to as Sample B) is obtained by drying.

[0123] 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, which can provide information on the individual compounds that make up the substance.

[0124] (2-2) Quantitative determination of the content of organic shrinkage inhibitor in negative electrode material As in (2-1) above, insoluble components are removed from the extract by filtration to obtain a solution. The ultraviolet-visible absorption spectrum of each of the obtained solutions is measured. The content of the organic shrinkage inhibitor in the negative electrode material is determined using the intensity of the peak characteristic of the organic shrinkage inhibitor and a previously prepared calibration curve.

[0125] When obtaining a lead-acid battery with an unknown content of organic shrinkage inhibitor and measuring the content of the organic shrinkage inhibitor, it may be impossible to precisely identify the structural formula of the organic shrinkage inhibitor, and therefore it may not be possible to use the same organic shrinkage inhibitor for the calibration curve. In such cases, 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 inhibitor extracted from the negative electrode of the battery, and the content of the organic shrinkage inhibitor is measured using the ultraviolet-visible absorption spectrum.

[0126] (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 the mixture was heated for approximately 20 minutes to dissolve the lead components as lead ions. The resulting solution was filtered to remove solids such as carbonaceous materials and barium sulfate.

[0127] 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.

[0128] (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.

[0129] 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.

[0130] (positive electrode plate) Positive electrode plates for lead-acid batteries can be classified into paste type, clad type, etc. Either paste type or clad type positive electrode plates may be used. A paste type positive electrode plate includes a positive electrode current collector and a positive electrode material. The positive electrode material is held by the positive electrode current collector. In a paste type positive electrode plate, the positive electrode material is the portion of the positive electrode plate excluding the positive electrode current collector. The positive electrode current collector may be formed by casting lead (Pb) or a lead alloy, or may be formed by processing a lead sheet or a lead alloy sheet. Examples of processing methods include expanding and punching. Using a lattice-shaped current collector as the positive electrode current collector is preferable because it makes it easier to support the positive electrode material. A clad positive electrode plate includes multiple porous tubes, a spine inserted into each tube, a current collector connecting the multiple spines, a positive electrode material filled into the tube with the spine inserted, and a spine protector connecting the multiple tubes. In a clad positive electrode plate, the positive electrode material is the positive electrode plate excluding the tube, spine, current collector, and spine protector. In a clad positive electrode plate, the spine and current collector are sometimes collectively referred to as the positive electrode collector.

[0131] A material such as a mat or pasting paper may be attached to the positive electrode plate. Such a material (attaching material) is used integrally with the positive electrode plate and is therefore included in the positive electrode plate. When the positive electrode plate includes an attaching material (such as a mat or pasting paper), the positive electrode material is the portion of the positive electrode plate excluding the positive electrode current collector and the attaching material in a paste-type positive electrode plate.

[0132] The lead alloy used for the positive electrode current collector is preferably a Pb-Sb alloy, a Pb-Ca alloy, or a Pb-Ca-Sn alloy 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.

[0133] 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.

[0134] Unformed paste-type positive plates are obtained by filling a positive current collector with positive paste, aging it, and drying it. The positive 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 spines connected by current collectors are inserted, and then joining multiple tubes with a spine protector. These unformed positive plates are then chemically formed to obtain positive plates.

[0135] 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.

[0136] (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.

[0137] A nonwoven fabric is a mat of intertwined fibers, 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 also contain components other than fibers (for example, acid-resistant inorganic powders, polymers as binders, etc.).

[0138] 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 a microporous membrane mainly composed of a polymer component is preferred. 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.

[0139] 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.

[0140] 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 portions are aligned with the horizontal direction of the lead-acid battery (e.g., so that the folded portions are parallel to the horizontal direction) or so that the folded portions are aligned with the vertical direction (e.g., so that the folded portions are 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 portions are aligned with the horizontal direction of the lead-acid battery, the positive and negative plates are positioned 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.

[0141] The maximum thickness T of the separator is, for example, 0.7 mm or more, and the maximum thickness T of the separator is, for example, 0.95 mm or less.

[0142] The maximum separator thickness T is measured on a sample of a separator removed from a fully charged lead-acid battery, washed with water to remove sulfuric acid, and dried under atmospheric pressure. More specifically, a cross-sectional photograph is taken of each separator sample in the thickness direction, and the maximum thickness t is measured on this cross-sectional photograph. The maximum thickness T is determined by averaging the maximum thicknesses t of all separators included in the electrode plate group. In a lead-acid battery having multiple electrode plate groups connected in series, the maximum separator thickness T is the average value of one electrode plate group (cell) located at the end and one electrode plate group (cell) located near the center.

[0143] (electrolyte) The electrolyte is an aqueous solution containing sulfuric acid, which may be gelled as necessary. The electrolyte may contain the above-mentioned polymer compound.

[0144] The electrolyte 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. When the electrolyte contains Al ions, the decrease in specific gravity during PSOC cycling is suppressed, thereby further reducing edge thinning of the negative electrode plate.

[0145] 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.

[0146] 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.

[0147] (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.

[0148] The number of electrodes in the electrode plate group may be one or more. From the viewpoint of ensuring higher capacity, the number of negative electrodes included in the electrode plate group is preferably two or more, and may be four or more, or six or more. Furthermore, if the electrode plate group includes nine or more negative electrodes, the decrease in the specific gravity of the electrolyte in the upper part of the electrode plate group during the PSOC cycle is suppressed, making it difficult for lead to dissolve in the ear portions, thereby further enhancing the effect of reducing ear thinning. Note that, if the number of negative electrodes included in the electrode plate group is n, the number of positive electrodes is (n-1) or more and (n+1) or less when n≧2, and is 1 or 2 when n=1.

[0149] As described above, the inter-electrode distance D is determined from the pitch between adjacent pairs of positive plates and the thickness of each of the positive and negative plates in a plate group removed from a fully charged lead-acid battery. The pitch is measured at the bottom of the cross section of the shelf portion that connects the lugs of multiple positive plates in parallel. For example, if a plate group includes six positive plates and seven negative plates, the center-to-center distance between the lugs is measured at five locations and averaged to determine the pitch. Similarly, if a plate group includes seven positive plates and seven negative plates, the center-to-center distance between the lugs is measured at six locations and averaged to determine the pitch. In a lead-acid battery with multiple series-connected plate groups, the pitch is the average value determined for any two plate groups (cells). For example, in the case of a 12V lead-acid battery containing six plate groups, the pitch is determined by measuring the center-to-center distance between the lugs of the first and fourth plate groups counting from the positive terminal and averaging the measured values.

[0150] The thickness of each electrode plate is measured, for example, with a micrometer at three locations along the periphery of the electrode plate, near both ends and near the center per side (a total of eight locations: positions indicated by numbers 1 to 8 in Figure 6), and then averaged. The thickness of the positive electrode plate is measured after washing with water to remove sulfuric acid and drying under atmospheric pressure, and the thickness of the negative electrode plate is measured after washing with water to remove sulfuric acid and vacuum drying (drying under a pressure lower than atmospheric pressure).

[0151] 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.

[0152] The difference between the inter-electrode distance D in the electrode assembly and the maximum separator thickness T (=DT) is, for example, 0.20 mm or less, preferably 0.15 mm or less, and more preferably 0.10 mm or less. When DT is within this range, the decrease in the specific gravity of the electrolyte in the upper part of the electrode assembly during PSOC cycles is suppressed, making it difficult for lead to dissolve in the edge portions, further enhancing the effect of reducing edge thinning. DT is, for example, -1.5 mm or more.

[0153] FIG. 1 shows an external view 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 by a lid 15 that has 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 the function of venting gas generated in the cell chambers 14 to the outside of the battery.

[0154] 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.

[0155] 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.

[0156] 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, for example, including 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.

[0157] In this specification, the amount of ear thinning, the liquid loss performance, and the PSOC life performance are evaluated according to the following procedures: The test battery used for the evaluation has a rated voltage of 12 V and a rated 5-hour rate capacity of 48 Ah.

[0158] (a) Evaluation 1: Ear thinning amount The negative electrode plate is removed from the test battery, washed with water, dried, and the thickness of the edge (initial thickness: t0) is measured. The test battery is charged and discharged according to the PSOC charge / discharge pattern (specifically, the pattern shown in Table 1) of the Battery Industry Association standard SBA S 0101 (lead-acid batteries for idle-stop vehicles). After charging and discharging, the negative plate is removed from the lead-acid battery, washed with water, and dried. Next, the negative plate is impregnated with epoxy resin and allowed to harden. The lug is cut in the thickness direction, and the lug thickness t1 is measured on the cut surface using a metallurgical microscope. The amount of reduction in lug thickness due to the charge / discharge cycle (= t0 - t1 (mm)) is then calculated as the amount of lug thinning. An Olympus GX53F metallurgical microscope is used. The thickness of the ear portion is determined by measuring the thickness at any five points on the ear portion with a vernier caliper and averaging the results.

[0159] [Table 1]

[0160] (b) Evaluation 2: Liquid reduction performance Using a test battery, the amount of electrolyte loss is determined from the change in mass of the test battery before and after the high-temperature durability test. More specifically, the mass (M0) of the test battery is measured before the high-temperature durability test. The test battery is subjected to the high-temperature durability test by repeating the following discharge and charge cycles 5,000 times in a water bath at 75°C ± 3°C. The mass (M1) of the test battery after the high-temperature durability test is measured. The amount of electrolyte loss is calculated by subtracting M1 from M0. Discharge: 25A, 2 minutes Charging: 14.8V, 25A, 10 minutes

[0161] (c) Evaluation 3: PSOC life performance Using the test battery, steps 1 to 3 of the charge / discharge pattern shown in Table 1 are repeated until the terminal voltage reaches 7 V or until 120,000 times are reached. Otherwise, charge / discharge is performed according to the charge / discharge pattern in Table 1, and the change in the end-of-discharge voltage (V) is measured.

[0162] (d) Evaluation 4: Potential change at the lug of the negative electrode plate Using the test battery, charge and discharge were carried out under the same conditions as in Evaluation 3 above, and the change in potential at the lug of the negative electrode plate was measured. The potential at the lug of each negative electrode plate was measured using a lead reference electrode (Pb / PbSO4).

[0163] (e) Evaluation 5: Change in specific gravity of electrolyte above the electrode group Using the test battery, charge and discharge were performed under the same conditions as in Evaluation 3 above. During this time, a small amount of electrolyte was removed from the top of the electrode assembly, and the change in specific gravity was measured using a hydrometer. The electrolyte was removed from a position 1 cm below the liquid surface of the electrolyte. The hydrometer used was a DMA35Ampere manufactured by Anton Paar.

[0164] A lead-acid battery according to one aspect of the present invention will be summarized below.

[0165] (1) A lead-acid battery, The lead-acid battery includes at least one cell including a plate group and an electrolyte; the electrode plate group includes a negative electrode plate, a positive electrode plate, and a separator interposed between the negative electrode plate and the positive electrode plate, The negative electrode plate includes a current collector having a lug portion and a negative electrode material, the ear portion has a surface layer containing Sn, The Sn content in the surface layer is less than 10 mass %, The negative electrode material is measured using deuterated chloroform as a solvent. 1 A lead-acid battery comprising a polymer compound having a peak in the range of 3.2 ppm to 3.8 ppm in the chemical shift of a H-NMR spectrum.

[0166] (2) In the above (1), the polymer compound contains an oxygen atom bonded to a terminal group and a -CH2- group and / or a -CH< group bonded to the oxygen atom, The aforementioned 1 In the H-NMR spectrum, the ratio of the integral value of the peak to the total integral value of the peak, the integral value of the peak due to the hydrogen atom of the -CH- group, and the integral value of the peak due to the hydrogen atom of the -CH< group may be 85% or more.

[0167] (3) In the above (1) or (2), the polymer compound is oxy C 2-4 It may contain a repeating structure of alkylene units.

[0168] (4) A lead-acid battery, The lead-acid battery includes at least one cell including a plate group and an electrolyte; the electrode plate group includes a negative electrode plate, a positive electrode plate, and a separator interposed between the negative electrode plate and the positive electrode plate, The negative electrode plate includes a current collector having a lug portion and a negative electrode material, the ear portion has a surface layer containing Sn, The Sn content in the surface layer is less than 10 mass %, The negative electrode material is oxy C 2-4 A lead-acid battery comprising a polymer compound containing a repeating structure of alkylene units.

[0169] (5) In any one of the above (1) to (4), the Sn content in the surface layer may be 7 mass % or less, 6 mass % or less, or 5 mass % or less.

[0170] (6) In any one of the above (1) to (5), the Sn content in the surface layer may be 0.01 mass % or more, 0.05 mass % or more, or 0.1 mass % or more.

[0171] (7) In any one of the above (1) to (6), the thickness of the surface layer may be 0.01 mm or more, 0.015 mm or more, or 0.02 mm or more.

[0172] (8) In any one of the above (1) to (7), the thickness of the surface layer may be 0.1 mm or less, or 0.05 mm or less.

[0173] (9) In any one of the above (1) to (8), the polymer compound may include a compound having an Mn of 300 or more, 400 or more, 500 or more, 600 or more, or 1000 or more.

[0174] (10) In any one of the above (1) to (9), the polymer compound may include a compound having an Mn of 5 million or less, 1 million or less, 100,000 or less, 50,000 or less, 20,000 or less, 15,000 or less, 10,000 or less, 5,000 or less, 4,000 or less, or 3,000 or less.

[0175] (11) In any one of the above (1) to (10), the polymer compound is oxy C 2-4 The compound contains at least one selected from the group consisting of a hydroxy compound having a repeating structure of an alkylene unit, an etherified product of the hydroxy compound, and an esterified product of the hydroxy compound, The hydroxy compound is polyC 2-4 Alkylene glycol, oxy C 2-4 Copolymers containing repeating alkylene units and polyol polyC2-4 It may be at least one selected from the group consisting of alkylene oxide adducts.

[0176] (12) In any one of the above (1) to (11), the polymer compound may contain at least a repeating structure of an oxypropylene unit.

[0177] (13) In the above (12), the polymer compound is selected from the group consisting of polypropylene glycol, polyoxypropylene-polyoxyethylene copolymers (polyoxypropylene-polyoxyethylene block copolymers, etc.), polypropylene glycol alkyl ethers (the above R 2 alkyl ethers (methyl ether, ethyl ether, butyl ether, etc.) in which R is an alkyl having 10 or less carbon atoms (or 8 or less, or 6 or less), polyoxyethylene-polyoxypropylene alkyl ethers (the above R 2 alkyl ethers (butyl ether, hydroxyhexyl ether, etc.) in which R is an alkyl having 10 or less carbon atoms (or 8 or less, or 6 or less), polypropylene glycol carboxylate (the above R 3 may contain at least one selected from the group consisting of polypropylene glycol carboxylates (such as polypropylene glycol acetate) in which the alkyl group has 10 or less carbon atoms (or 8 or less, or 6 or less), and polypropylene oxide adducts of triol or higher polyols (such as polypropylene oxide adducts of glycerin).

[0178] (14) In the above (12) or (13), the proportion of the oxypropylene units in the polymer compound may be 5 mol % or more, 10 mol % or more, or 20 mol % or more.

[0179] (15) In any one of the above (12) to (14), the proportion of the oxypropylene units in the polymer compound may be 100 mol% or less, 90 mol% or less, 75 mol% or less, 60 mol% or less, 50 mol% or less, or 43 mol% or less.

[0180] (16) In any one of the above (1) to (15), the content of the polymer compound in the negative electrode material may be 8 ppm or more, 10 ppm or more, or 15 ppm or more by mass.

[0181] (17) In any one of the above (1) to (16), the content of the polymer compound in the negative electrode material may be 400 ppm or less, 380 ppm or less, or 370 ppm or less by mass.

[0182] (18) In any one of the above (1) to (17), the negative electrode material may further contain an organic shrinkage preventer.

[0183] (19) In the above (18), the content of the organic shrinkage preventer in the negative electrode material may be 0.01% by mass or more, or 0.05% by mass or more.

[0184] (20) In the above (18) or (19), the content of the organic shrinkage preventer in the negative electrode material may be 1.0% by mass or less, or 0.5% by mass or less.

[0185] (21) In any one of the above (1) to (20), the negative electrode material may further contain a carbonaceous material.

[0186] (22) In the above (21), the content of the carbonaceous material in the negative electrode material may be 0.05% by mass or more, or 0.10% by mass or more.

[0187] (23) In the above (21) or (22), the content of the carbonaceous material in the negative electrode material may be 5% by mass or less, or 3% by mass or less.

[0188] (24) In any one of the above (1) to (23), the negative electrode material may further contain barium sulfate.

[0189] (25) In the above (24), the content of the barium sulfate in the negative electrode material may be 0.05% by mass or more, or 0.10% by mass or more.

[0190] (26) In the above (24) or (25), the content of the barium sulfate in the negative electrode material may be 3% by mass or less, or 2% by mass or less.

[0191] (27) In any one of the above (1) to (26), the difference between the distance between the positive electrode plate and the negative electrode plate in the electrode plate group and the maximum thickness of the separator (=DT) may be 0.20 mm or less, 0.15 mm or less, or 0.10 mm or less.

[0192] (28) In any one of the above (1) to (27), the difference (=DT) between the distance between the positive electrode plate and the negative electrode plate in the electrode plate group and the maximum thickness of the separator may be −1.5 mm or more.

[0193] (29) In any one of the above (1) to (28), the maximum thickness T of the separator may be 0.7 mm or more.

[0194] (30) In any one of the above (1) to (29), the maximum thickness T of the separator may be 0.95 mm or less.

[0195] (31) In any one of the above (1) to (30), the number of negative electrode plates in the electrode plate group may be one or more, two or more, four or more, six or more, or nine or more.

[0196] (32) In any one of the above (1) to (30), in at least one of the cells, the electrode plate group includes two or more of the positive electrode plates and two or more of the negative electrode plates, and has a structure in which the positive electrode plates and the negative electrode plates are alternately stacked with the separator interposed therebetween; The electrode plate group may include nine or more negative electrode plates.

[0197] (33) In the above (31) or (32), if the number of negative plates included in the electrode plate group is n, the number of positive plates is (n-1) or more and (n+1) or less when n≧2, and may be 1 or 2 when n=1.

[0198] (34) In any one of the above (1) to (33), the electrolytic solution may contain Al ions.

[0199] (35) In any one of the above (1) to (34), the specific gravity of the electrolyte at 20° C. in the fully charged lead-acid battery may be 1.20 or more or 1.25 or more.

[0200] (36) In any one of the above (1) to (35), the specific gravity of the electrolyte at 20° C. in the fully charged lead-acid battery may be 1.35 or less or 1.32 or less.

[0201] [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.

[0202] Lead-acid batteries E1 to E16 and C1 to C4 (1) Preparation of negative electrode plate A Pb-Sn alloy sheet is stacked on a Pb-Ca-Sn alloy sheet, rolled in this state, and then expanded. This results in a surface layer of a lead alloy containing Sn on the edge portions of the expanded grid made of a Pb-Ca-Sn alloy. The Pb-Sn alloy sheet used has a composition such that the Sn content of the surface layer determined by the procedure described above is the value shown in Tables 2 to 4. The thickness of the surface layer measured by the procedure described above is 0.02 mm. The grid having the surface layer formed in this way on its edge portions is used as a negative electrode current collector. In the lead-acid battery C4, an expanded grid made of a Pb-Ca-Sn alloy with no surface layer provided on the edge portions is used.

[0203] A negative electrode paste is prepared by mixing lead powder, water, dilute sulfuric acid, carbon black, a polymer compound, sodium lignosulfonate as an organic shrinkage preventer, and barium sulfate. The components are mixed so that the contents of the organic shrinkage preventer, carbon black, and barium sulfate in the negative electrode material, all determined by the procedures described above, are 0.1 mass%, 0.2 mass%, and 0.4 mass%, respectively. The polymer compounds shown in Tables 2 to 4 are mixed with the other components so that the contents of the polymer compounds in the negative electrode material, determined by the procedures described above, are the values ​​shown in Tables 2 to 4. The negative electrode paste is filled into the mesh portion of a negative electrode current collector, aged, and dried to obtain an unformed negative electrode plate.

[0204] (2) 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 as a positive electrode current collector, and the resulting plate is aged and dried to obtain an unformed positive electrode plate.

[0205] (3) Preparation of lead-acid batteries The unformed negative electrode plates are housed in a pouch-shaped separator made of a microporous polyethylene film, and eight unformed negative electrode plates and seven unformed positive electrode plates form an electrode plate group. The electrode plate group is inserted into a battery case, a predetermined amount of sulfuric acid aqueous solution is poured in as the electrolyte, and chemical formation is performed inside the battery case to produce a wet lead-acid battery with a rated voltage of 12 V and a rated capacity of 48 Ah (5-hour rate). The specific gravity of the electrolyte in a fully charged lead-acid battery at 20°C is 1.28. The above chemical formation brings the lead-acid battery into a fully charged state.

[0206] In addition, when the polymer compound has a repeating structure of oxyethylene units, the polymer compound measured by the above-mentioned procedure 1 In the H-NMR spectrum, a peak derived from -CH2- of the oxyethylene unit is observed in the chemical shift range of 3.2 ppm to 3.8 ppm. When the polymer compound has a repeating structure of oxypropylene units, the peak of the polymer compound measured by the above-mentioned procedure 1In 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 of the peak between 3.2 ppm and 3.8 ppm accounts for 85 to 100% of the total integral of this peak, the integral of the peaks of hydrogen atoms of -CH- groups bonded to oxygen atoms, and the integral of the peaks of hydrogen atoms of -CH< groups bonded to oxygen atoms.

[0207] (4) Evaluation (a) Evaluation 1: Ear thinning amount The negative electrode plate is removed from the lead-acid battery fabricated above, and the amount of thinning at the edge is determined using the procedure described above. The amount of thinning at the edge of each lead-acid battery is evaluated relative to the amount of thinning at the edge of lead-acid battery C1, which is set to 1.

[0208] (b) Evaluation 2: Liquid reduction performance Using the lead-acid battery, the amount of liquid loss is determined using the procedure described above. The liquid loss performance is evaluated as a relative ratio when the amount of liquid loss of lead-acid battery C1 is set to 1.

[0209] The results are shown in Tables 2 to 4. The Mn of the polymer compounds shown in Tables 2 to 4 is the Mn determined by the procedure already described. E1 to E16 are examples, and C1 to C4 are comparative examples.

[0210] [Table 2]

[0211] [Table 3]

[0212] [Table 4]

[0213] As shown in Table 2, when the negative electrode material does not contain a polymer compound, and the Sn content in the surface layer of the ear portion of the negative electrode plate is 10% by mass or 30% by mass, the amount of ear thinning can be significantly reduced from 10.5 to 1.2 or 1, compared to when no surface layer is provided (comparison of C4 with C2 and C1). In contrast, when the Sn content in the surface layer is less than 10% by mass, the effect of reducing ear thinning is low (comparison of C4 with C3, and comparison of C3 with C2 and C1). However, even when the Sn content in the surface layer is less than 10% by mass, the amount of ear thinning can be reduced when the negative electrode material contains a polymer compound (comparison of C3 with E1 to E3). Furthermore, the amount of liquid loss is also reduced in E1 to E3.

[0214] As shown in Table 3, even when the Sn content in the surface layer is as low as 0.1% by mass, the amount of ear thinning can be significantly reduced by including a polymer compound in the negative electrode material (E4). From the results of the amount of ear thinning in E4, it can be inferred that the amount of ear thinning can be reduced by combining it with a polymer compound even when the Sn content in the surface layer is very small, such as 0.01% by mass or more or 0.05% by mass or more. The Sn content in the surface layer needs to be less than 10% by mass; even when it is 7% by mass or less or 5% by mass or less, the combination with a polymer compound can significantly reduce ear thinning.

[0215] As shown in Tables 2 and 3, the polymer content in the negative electrode material is preferably 15 ppm or more to further enhance the effect of reducing ear thinning. There is no particular upper limit to the polymer content in the negative electrode material, but even at 400 ppm or less, an excellent effect of reducing ear thinning can be obtained.

[0216] Also, as shown in Table 4, oxy C 2-4 Even when an ether or ester of a hydroxy compound having a repeating alkylene unit structure is used, it is possible to reduce edge thinning of the negative electrode plate and reduce liquid loss.

[0217] 《Lead acid battery E17~E19》 (1) Preparation of negative and positive electrodes Seven, eight, or nine unformed negative plates are fabricated per cell by adjusting the amount of lead per negative plate and the thickness of the negative plate so that the total amount of lead in the negative electrode material per cell is the same. Similarly, six, seven, or eight unformed positive plates are fabricated per cell by adjusting the amount of lead per positive plate and the thickness of the positive plate so that the total amount of lead in the positive electrode material per cell is the same. The fabrication of the negative and positive plates is otherwise the same as for lead-acid battery E1.

[0218] (2) Preparation of lead-acid batteries Unformed negative plates are housed in a pouch-shaped separator made of a polyethylene microporous film, and unformed negative plates and unformed positive plates are stacked to form an electrode plate assembly. Lead-acid battery E17 uses seven unformed negative plates and six unformed positive plates. Lead-acid battery E18 uses eight unformed negative plates and seven unformed positive plates. Lead-acid battery E19 uses nine unformed negative plates and eight unformed positive plates. An aqueous sulfuric acid solution containing Al ions at a concentration of 17 g / L is used as the electrolyte. The specific gravity of the electrolyte in a fully charged lead-acid battery at 20°C is 1.285. Other than these, lead-acid batteries E17 to E19 are fabricated in the same manner as lead-acid battery E1. E17 to E19 are examples.

[0219] (3) Evaluation (c) Evaluation 3: PSOC life performance Using the obtained lead-acid battery, the PSOC life performance is evaluated according to the procedure described above. The results are shown in Figure 2.

[0220] (d) Evaluation 4: Potential change at the lug of the negative electrode plate Using the obtained lead-acid battery, the change in potential (voltage relative to the reference electrode) at the lug of the negative electrode plate is measured according to the procedure described above. The results are shown in Figure 3.

[0221] (e) Evaluation 5: Change in specific gravity of electrolyte above the electrode group Using the obtained lead-acid battery, the change in the specific gravity of the electrolyte above the electrode plate assembly is measured according to the procedure described above. The results are shown in Figure 4.

[0222] As shown in Figure 2, when the plate group has seven or eight negative plates, the terminal voltage drops sharply once the PSOC cycles exceed 50,000 or 60,000. Along with this sudden drop in terminal voltage, the negative plate's edge thinning also becomes noticeable, leading to the end of its life. In contrast, when the plate group has nine negative plates, there is no sudden drop in terminal voltage, and the edge thinning of the negative plate is suppressed, even after the PSOC cycles exceed 100,000.

[0223] As shown in Figure 3, the change in potential at the lug of the negative plate during PSOC cycling is almost the same regardless of the number of negative plates in the electrode plate assembly. Meanwhile, when the number of negative plates in the electrode plate assembly is seven or eight, the specific gravity of the electrolyte in the upper part of the electrode plate assembly decreases around the cycle number at which a sudden drop in terminal voltage was observed in Figure 2 (Figure 4). In contrast, when the number of negative plates is nine, no sudden drop in the specific gravity of the electrolyte is observed (Figure 4). From Figures 3 and 4, it is believed that the suppression of edge thinning of the negative plate when there are nine negative plates in Figure 2 is due to the suppression of the decrease in the specific gravity of the electrolyte in the upper part of the electrode plate assembly. From these results, it is believed that an electrode plate assembly with more than nine negative plates can achieve the same effect as when there are nine negative plates. Therefore, from the perspective of further suppressing edge thinning, it is preferable for the electrode plate assembly to have nine or more negative plates.

[0224] Lead-acid batteries E20 to E23 and E24 to E27 By adjusting the sulfuric acid concentration, electrolytes with specific gravities of 1.20, 1.22, 1.24, and 1.28 at 20°C for fully charged lead-acid batteries are prepared. Lead-acid batteries E20, E21, E22, and E23 are fabricated in the same manner as lead-acid battery E19, except for using the prepared electrolytes.

[0225] An aqueous sulfuric acid solution containing 7 g / L of Na ions instead of Al ions is used as the electrolyte. By adjusting the sulfuric acid concentration, an electrolyte is prepared in which the specific gravity of a fully charged lead-acid battery at 20°C is 1.20, 1.22, 1.24, or 1.28. Lead-acid batteries E24, E25, E26, and E27 are fabricated in the same manner as lead-acid battery E19, except for using the prepared electrolyte. E20 to E23 and E24 to E27 are examples.

[0226] Using each lead-acid battery, the amount of thinning at the edge of the negative electrode plate was measured in the same manner as in Evaluation 1. Figure 5 shows the relationship between the specific gravity of the electrolyte and the amount of thinning at the edge.

[0227] As shown in FIG. 5, when the electrolyte contains Al ions, the amount of thinning of the edge of the negative electrode plate can be significantly reduced compared to when the electrolyte contains Na ions. [Industrial Applicability]

[0228] The lead-acid batteries according to one aspect and another aspect of the present invention are suitable for use in idle stop-start vehicles, for example, as lead-acid batteries for ISSs that are charged and discharged under PSOC conditions. Furthermore, lead-acid batteries can be suitably used, for example, as starting power sources for vehicles (cars, motorcycles, etc.) and industrial power storage devices (for example, power sources for electric vehicles (forklifts, etc.)). Note that these are merely examples, and the uses of lead-acid batteries are not limited to these. [Explanation of symbols]

[0229] 1:Lead acid battery 2: Negative electrode plate 3: Positive electrode plate 4: Separator 5: Positive electrode shelf 6: Negative electrode shelf 7: Positive pole 8: Through connector 9: Negative pole 11: Plate group 12:Battery container 13: Bulkhead 14: Cell Room 15: Lid 16: Negative terminal 17: Positive terminal 18: Liquid vent plug

Claims

1. A lead-acid battery, The lead-acid battery includes at least one cell including a plate group and an electrolyte; the electrode plate group includes a negative electrode plate, a positive electrode plate, and a separator interposed between the negative electrode plate and the positive electrode plate, The negative electrode plate includes a current collector having a lug portion and a negative electrode material, the ear portion has a surface layer containing Sn, The Sn content in the surface layer is less than 10 mass %, The negative electrode material is measured using deuterated chloroform as a solvent. １ The polymer compound has a peak in the range of 3.2 ppm to 3.8 ppm in the chemical shift of the H-NMR spectrum, a content of the polymer compound in the negative electrode material of 400 ppm or less by mass;

2. The polymer compound has an oxygen atom bonded to a terminal group and a —CH ２ - group and / or -CH< group, The aforementioned １ In the H-NMR spectrum, the integral value of the peak and the -CH ２ 2. The lead acid battery according to claim 1, wherein the ratio of the integral value of the peak to the sum of the integral value of the peak of the hydrogen atom of the - group and the integral value of the peak of the hydrogen atom of the -CH< group is 85% or more.

3. The polymer compound is oxy C ２－４ The lead acid battery according to claim 1 or 2, comprising a repeating structure of alkylene units.

4. A lead-acid battery, The lead-acid battery includes at least one cell including a plate group and an electrolyte; the electrode plate group includes a negative electrode plate, a positive electrode plate, and a separator interposed between the negative electrode plate and the positive electrode plate, The negative electrode plate includes a current collector having a lug portion and a negative electrode material, the ear portion has a surface layer containing Sn, The Sn content in the surface layer is less than 10 mass %, The negative electrode material is oxyC ２－４ The polymer compound includes a repeating structure of an alkylene unit, a content of the polymer compound in the negative electrode material of 400 ppm or less by mass;

5. The lead acid battery according to any one of claims 1 to 4, wherein the Sn content in the surface layer is 7 mass% or less.

6. The lead acid battery according to any one of claims 1 to 5, wherein the Sn content in the surface layer is 0.01 mass% or more.

7. The lead acid battery according to any one of claims 1 to 6, wherein the content of the polymer compound in the negative electrode material is 15 ppm or more by mass.

8. In at least one of the cells, the electrode plate group includes two or more positive electrode plates and two or more negative electrode plates, and has a structure in which the positive electrode plates and the negative electrode plates are alternately stacked with the separator interposed therebetween, The lead-acid battery according to any one of claims 1 to 7, wherein the electrode plate group includes nine or more negative electrode plates.

9. The lead acid battery according to any one of claims 1 to 8, wherein a difference between the distance between the positive electrode plate and the negative electrode plate in the electrode plate group and the maximum thickness of the separator is 0.15 mm or less.

10. The lead acid battery according to any one of claims 1 to 9, wherein the electrolyte contains Al ions.

11. The polymer compound is oxy C ２－４ The compound contains at least one selected from the group consisting of a hydroxy compound having a repeating structure of an alkylene unit, an etherified product of the hydroxy compound, and an esterified product of the hydroxy compound, The hydroxy compound is polyC ２－４ Alkylene glycol, oxy C ２－４ A copolymer containing a repeating alkylene unit, and a polyol, polyC ２－４ The lead acid battery according to any one of claims 1 to 10, wherein the lead acid battery is at least one selected from the group consisting of alkylene oxide adducts.

12. The lead acid battery according to any one of claims 1 to 11, wherein the polymer compound contains a repeating structure of oxypropylene units.

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