lead-acid batteries

Abstract

This lead-acid storage battery is provided with a negative electrode plate, a positive electrode plate, and an electrolyte solution. The negative electrode plate includes a negative electrode collector and a negative electrode material. The negative electrode material includes a carbonaceous material, and the content of the carbonaceous material contained in the negative electrode material is at least 0.9 mass%. The arithmetic average roughness Ra of the surface of the negative electrode collector is 1 μm to 22 μm, inclusive.

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. Lead-acid batteries include negative and positive plates, separators (or mats), and electrolytes. Each plate includes a current collector and an electrode material.

[0003] In lead-acid batteries, attempts have been made to add a conductive carbonaceous material such as carbon to the negative electrode material in order to suppress the accumulation of lead sulfate in the negative electrode. For example, Patent Document 1 proposes that, for a sealed lead-acid battery using a paste-type negative electrode plate, the active material of the paste-type negative electrode plate contains 0.4 to 4 wt % of carbon or graphite and 0.001 to 0.06 wt % of sodium silicate or potassium silicate.

[0004] Patent Document 2 proposes adding 0.1 to 0.4% by weight of carbon to the lead powder in a sealed lead-acid battery in which 0.5% by weight or less of lignin is added to the lead powder in the active material of the negative electrode plate.

[0005] Patent Document 3 proposes a substrate for a lead-acid battery made of a lead-calcium-based lead alloy, in which the calcium content in the alloy is less than 0.05 mass %, and the surface roughness (Rz) of the substrate is 15 μm or more. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-43849 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-42794 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-158433 Summary of the Invention [Problem to be solved by the invention]

[0007] When carbon black is used as the carbonaceous material, if the content of carbon black in the negative electrode material is increased, the discharge end voltage may drop significantly with repeated PSOC cycles, leading to the end of the battery's life. [Means for solving the problem]

[0008] One aspect of the present invention relates to a lead-acid battery including a negative electrode plate, a positive electrode plate, and an electrolyte; the negative electrode plate includes a negative electrode current collector and a negative electrode material; the negative electrode material includes a carbonaceous material, a content of the carbonaceous material in the negative electrode material is 0.9 mass% or more; and the arithmetic mean roughness Ra of the surface of the negative electrode current collector is 1 μm or more and 22 μm or less. [Brief explanation of the drawings]

[0009] [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] 1 is a graph showing the relationship between the surface roughness Ra of a negative electrode current collector and the amount of fallen negative electrode material after completion of a PSOC cycle test. DETAILED DESCRIPTION OF THE INVENTION

[0010] The carbonaceous material added to the negative electrode material enhances charge acceptance and inhibits lead sulfate accumulation. This improves the lifespan of lead-acid batteries, especially when they are repeatedly used in a partially charged state (PSOC). However, when the carbonaceous material content in the negative electrode material is high (e.g., 0.9% by mass or more), the end-of-discharge voltage drops significantly with repeated PSOC cycles, potentially reaching the end of the battery's lifespan. When a lead-acid battery is disassembled after its end of life, the negative electrode material is observed to fall off from the negative electrode current collector. This suggests that carbon particles penetrate between the lead particles (active material) and between the lead particles and the negative electrode current collector, reducing the adhesion between the negative electrode current collector and the active material, causing the negative electrode material to peel off from the negative electrode current collector and ultimately reaching the end of its lifespan. In particular, when carbon black is used as the carbonaceous material, its small particle size makes it easy to form a conductive path between the lead particles and the negative electrode current collector, but it also easily penetrates between the lead particles and the negative electrode current collector, reducing the adhesion between the negative electrode current collector and the active material.

[0011] In view of the above, a lead-acid battery according to one aspect of the present invention includes a negative electrode plate, a positive electrode plate, and an electrolyte. The negative electrode plate includes a negative electrode current collector and a negative electrode material. The negative electrode material includes a carbonaceous material. The content of the carbonaceous material in the negative electrode material is 0.9 mass% or more. The arithmetic mean roughness Ra of the surface of the negative electrode current collector is 1 μm or more and 22 μm or less.

[0012] In this lead-acid battery, even when a carbonaceous material is added to the negative electrode material at a high concentration of 0.9% by mass or more, the surface of the negative electrode current collector is roughened to increase the surface roughness, thereby improving adhesion between the negative electrode current collector and the active material and preventing the negative electrode material from peeling off from the negative electrode current collector. This prevents the end of life due to the falling off of the negative electrode material and achieves a long life.

[0013] From the viewpoint of suppressing peeling of the negative electrode material and realizing a long life, the surface roughness of the negative electrode current collector should be 1 μm or more in arithmetic mean roughness Ra, preferably 2 μm or more, and more preferably 4 μm or more. On the other hand, from the viewpoint of suppressing corrosion of the negative electrode current collector and suppressing active material loss due to corrosion, the surface roughness of the negative electrode current collector should be 22 μm or less in arithmetic mean roughness Ra, preferably 15 μm or less or 10 μm or less.

[0014] The arithmetic mean roughness Ra of the surface of the negative electrode current collector is preferably 1 μm or more and 15 μm or less (or 1 μm or more and 10 μm or less), more preferably 2 μm or more and 15 μm or less (or 2 μm or more and 10 μm or less), or more preferably 4 μm or more and 15 μm or less (or 4 μm or more and 10 μm or less).

[0015] The surface roughness of the negative electrode current collector can be determined by removing the negative electrode plate from the lead-acid battery, removing the negative electrode material as described below to expose the surface of the negative electrode current collector, and then measuring the arithmetic mean roughness Ra in a predetermined region on the surface of the negative electrode current collector using a surface roughness meter.

[0016] The density of the negative electrode material is 3.4 g / cm 3 In this case, by roughening the surface of the negative electrode current collector, the adhesion between the negative electrode current collector and the active material is significantly improved, and the falling off of the negative electrode material can be significantly suppressed. On the other hand, in the production of a lead-acid battery, from the viewpoint of facilitating the filling of the negative electrode paste into the negative electrode current collector, the density of the negative electrode material is set to 4.1 g / cm or more. 3 Less than 3.8 g / cm is preferred 3 More preferably, the density of the negative electrode material is 3.4 g / cm 3 More than 4.1g / cm 3 Less than 3.4 g / cm is preferred 3 More than 3.8g / cm 3 The following is more preferable: Here, the density of the negative electrode material means the bulk density, which is measured by the method described below.

[0017] The negative electrode current collector may be a punched current collector, the surface roughness of which can be easily controlled by providing irregularities in the die used for punching.

[0018] The carbon black content in the negative electrode material may be 1.5% by mass or more, and may be, for example, 5% by mass or less, 3% by mass or less, or 2.1% by mass or less.

[0019] The negative electrode material is measured using deuterated chloroform as the solvent. 1 The polymer compound may contain a peak in the range of 3.2 ppm to 3.8 ppm in the chemical shift of the H-NMR spectrum.

[0020] A lead-acid battery according to another aspect of the present invention includes a negative electrode plate, a positive electrode plate, and an electrolyte. The negative electrode plate includes a negative electrode current collector and a negative electrode material. The negative electrode material includes a carbonaceous material. The content of the carbonaceous material in the negative electrode material is 0.3 mass% or more. The negative electrode material includes the above-mentioned polymer compound. In this case, the content of the carbonaceous material in the negative electrode material may be 0.9 mass% or more, or may be 1.5 mass% or more. The content of the carbonaceous material may be, for example, 5 mass% or less, 3 mass% or less, or 2.1 mass% or less. The carbonaceous material preferably includes carbon black.

[0021] 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.

[0022] The polymer compound has the effect of increasing the hydrogen overvoltage by covering the surface of lead in the negative electrode material. This improves charge acceptance and makes it less likely that a side reaction that generates hydrogen will occur during overcharging or charging. In addition, the polymer compound is a 2-4The repeating alkylene unit structure makes it easy to form a linear structure, so a small amount can cover the lead surface thinly and widely. As a result, even a very small amount of polymer compound can reduce the hydrogen generation reaction, the amount of electricity during overcharge, and the amount of gas generation.

[0023] In addition, when the negative electrode material contains a large amount of a carbonaceous material (e.g., carbon black), low-temperature high-rate discharge performance may be reduced. The polymer compound has the effect of suppressing the reduction in low-temperature high-rate discharge performance that accompanies the inclusion of a carbonaceous material in the negative electrode material. As a result, in the lead-acid batteries according to one aspect and another aspect of the present invention, high low-temperature high-rate discharge performance can be maintained even when the carbonaceous material is added to the negative electrode material in a high content of 0.9 mass% or more.

[0024] The effects of the polymer compound as described above are exhibited by covering the surface of lead with the polymer compound. Therefore, it is important that the polymer compound be present in the vicinity of lead, which allows the effects of the polymer compound to be exhibited effectively. Therefore, it is important that the negative electrode material contains a polymer compound, regardless of whether or not polymer compounds are contained in components of the lead-acid battery other than the negative electrode material.

[0025] The content of the polymer compound in the negative electrode material may be 600 ppm or less by mass to prevent the polymer compound film covering the lead surface from becoming thicker and conversely reducing charge acceptance. The content of the polymer compound in the negative electrode material is preferably 30 ppm or more and 600 ppm or less by mass. When the content of the polymer compound is in this range, the effect of improving low-temperature high-rate discharge performance is significant.

[0026] The polymeric compounds may include oxygen atoms attached to end groups and -CH2- and / or -CH< groups attached to the oxygen atoms. 1In the H-NMR spectrum, the ratio of the integral of the peak between 3.2 ppm and 3.8 ppm to the total integral of this peak, the integral of the peak of the hydrogen atoms of the -CH2- groups bonded to the oxygen atoms, and the integral of the peak 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, which is thought to make it easier for the polymer compound to adsorb to lead and to form a linear structure that makes it easier to thinly coat the lead surface. This can enhance the improvement of low-temperature high-rate discharge performance.

[0027] 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 onto lead and that the linear structure makes it easier to thinly coat the lead surface, thereby further improving the low-temperature high-rate discharge performance.

[0028] 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 alkylene units, 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 polyC 2-4 It may be at least one selected from the group consisting of alkylene oxide adducts.

[0029] The polymer compound may contain 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 suppressing thick adhesion to the lead surface. Therefore, it is possible to more effectively reduce the amount of overcharge electricity and gas generation, and further enhance the effect of improving low-temperature high-rate discharge performance.

[0030] The polymer compound has one or more hydrophobic groups, and at least one of the hydrophobic groups may be a long-chain aliphatic hydrocarbon group having 8 or more carbon atoms. The action of such hydrophobic groups prevents excessive coating of the polymer compound on the lead surface, making it easier to simultaneously prevent a decrease in charge acceptance and reduce the amount of overcharge electricity. The polymer compound preferably contains a repeating structure of oxyethylene units. By including a repeating structure of oxyethylene units with high hydrophilicity in the polymer compound, the polymer compound can be selectively adsorbed onto lead. The balance between the hydrophobic group and the hydrophilic group can more effectively reduce the amount of overcharge electricity and further enhance the improvement in low-temperature high-rate discharge performance.

[0031] Preferred examples of the polymer compound include at least one selected from the group consisting of polyethylene glycol, polyethylene glycol oleate, polyethylene glycol dilaurate, polyethylene glycol distearate, and polypropylene glycol.

[0032] In a lead-acid battery, 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).

[0033] 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.

[0034] In this specification, the surface roughness of the positive electrode current collector, the contents of the polymer compound and the organic shrinkage preventer in the negative electrode material, and the density (bulk density) of the negative electrode material are determined for a negative electrode plate removed from a fully charged lead-acid battery.

[0035] (Terminology explanation) (electrode material) The negative electrode material and the positive electrode material are usually held by a current collector. The electrode material is the portion of the electrode plate excluding the current collector. A mat, pasting paper, or other member may be attached to the electrode plate. Such members (also called attachment members) are used integrally with the electrode plate and are therefore considered to be included in the electrode plate. When the electrode plate includes an attachment member (such as a mat or pasting paper), the electrode material is the portion of the electrode plate excluding the current collector and attachment member.

[0036] Among positive electrode plates, a clad positive electrode plate includes multiple porous tubes, a metal core inserted into each tube, a current collector connecting the multiple metal cores, a positive electrode material filled into the tubes into which the metal cores are inserted, and a connecting seat connecting the multiple tubes. In a clad positive electrode plate, the positive electrode material excludes the tubes, the metal cores, the current collector, and the connecting seat. In a clad positive electrode plate, the metal core and the current collector are sometimes collectively referred to as a positive electrode current collector.

[0037] (surface roughness) The surface roughness Ra of the negative electrode current collector is the arithmetic mean roughness Ra defined in JIS B 0601:2001. The arithmetic mean roughness Ra is measured using a surface roughness meter on the negative electrode current collector, which is obtained by removing the negative electrode material from the negative electrode plate of a lead-acid battery according to the following procedure, and exposing the surface. For example, the arithmetic mean roughness Ra can be measured using a "VK-X100 LASER MICROSCOPE" manufactured by Keyence Corporation.

[0038] First, the lead-acid battery is disassembled and the negative electrode plate is removed. The removed negative electrode plate is washed with water to remove sulfuric acid and then vacuum dried (dried under a pressure lower than atmospheric pressure). Next, the negative electrode material is separated from the negative electrode plate, and the current collector is further washed with water and then vacuum dried to obtain a negative electrode current collector from which the negative electrode material has been removed.

[0039] The negative electrode current collector is divided into three sections in the vertical and horizontal directions, for a total of nine regions (it is not necessary to cut the negative electrode plate to divide it into the nine regions). At least one measurement location is arbitrarily selected for each of the nine regions, and the arithmetic mean roughness Ra of the surface at the measurement location is measured. The average value of the arithmetic mean roughnesses Ra measured at nine or more locations using the above method is defined as the surface roughness Ra of the negative electrode current collector. The measurement location may be a portion corresponding to the horizontal or vertical ribs of the current collector. In the case of a punched current collector, the measurement location is arbitrarily selected from the surface of the negative electrode current collector that is approximately parallel to the main surface of the negative electrode plate.

[0040] (bulk density of negative electrode material) The bulk density of the negative electrode material is the density (g / cm) calculated by dividing the mass of the negative electrode material by the bulk volume determined by mercury intrusion porosimetry. 3 The bulk density is determined for unground negative electrode material taken from a negative plate removed from a lead-acid battery.

[0041] (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. In the above (i), the peak in the range of 3.2 ppm to 3.8 ppm is oxy-C2-4 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.

[0042] (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).

[0043] (organic shrinkage preventer) The organic shrinkage inhibitor refers to an organic compound among compounds that have the function of suppressing the shrinkage of lead, which is the negative electrode active material, when a lead-acid battery is repeatedly charged and discharged.

[0044] (number average molecular weight) The number average molecular weight (Mn) is determined by gel permeation chromatography (GPC). The standard substance used to determine Mn is polyethylene glycol.

[0045] (fully charged) The fully charged state of a flooded lead-acid battery is defined by JIS D 5301:2019. More specifically, a fully charged state is defined as a state in which a lead-acid battery is charged in a water tank at 25°C ± 2°C with a current (A) 0.2 times the rated capacity (unit: Ah) until the terminal voltage (V) during charging or the electrolyte density converted to 20°C temperature shows a constant value to three significant digits three times consecutively. For a valve-regulated lead-acid battery, a fully charged state is defined as a state in which a battery is charged in an air tank at 25°C ± 2°C with a constant current / constant voltage of 2.23 V / cell with a current (A) 0.2 times the rated capacity (unit: Ah), and charging is terminated when the charging current during constant voltage charging reaches a value (A) 0.005 times the rated capacity (unit: Ah).

[0046] A fully charged lead-acid battery refers to a fully charged lead-acid battery that has already been formed. A lead-acid battery can be fully charged immediately after formation, or after some time has passed since formation (for example, a lead-acid battery that has been in use (preferably in the early stages of use) after formation can be fully charged). A battery in the early stages of use refers to a battery that has not been in use for very long and has hardly deteriorated at all.

[0047] (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.

[0048] 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.

[0049] [Lead acid battery] (negative plate) The negative electrode plate usually includes a negative electrode current collector in addition to a negative electrode material.

[0050] (Negative electrode 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.

[0051] The lead alloy used for the negative electrode current collector may be any of a Pb-Sb alloy, a Pb-Ca alloy, and a Pb-Ca-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, Cu, and the like. The negative electrode current collector may have a surface layer. The surface layer and the inner layer of the negative electrode current collector may have different compositions. The surface layer may be formed on a part of the negative electrode current collector. The surface layer may be formed on the lug portion of the negative electrode current collector. The surface layer of the lug portion may contain Sn or an Sn alloy.

[0052] To improve adhesion between the negative electrode material and the negative electrode current collector and prevent the negative electrode material from peeling off and falling off the negative electrode plate, the surface of the negative electrode current collector is roughened to an arithmetic mean roughness Ra of 1 μm or more. In the case of expanded grid or punched current collectors, roughening can be achieved, for example, by pressing a plate with fine irregularities against the surface of a lead or lead alloy sheet before processing or the surface of the processed current collector, or by blasting the surface of the current collector. In this case, roughening can be achieved on a sheet-like current collector before processing, or during or after processing the current collector. In the case of cast current collectors, roughening can be achieved efficiently by creating fine irregularities on the surface of a mold used for casting.

[0053] (Negative electrode material) The negative electrode material includes carbon black. The negative electrode material further includes a negative electrode active material (specifically, lead or lead sulfate) that exhibits capacity through an oxidation-reduction reaction. The negative electrode material may further include an organic shrinkage inhibitor. The negative electrode material may include at least one selected from the group consisting of carbonaceous materials other than carbon black 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 electrode plates are usually made using lead powder.

[0054] (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.

[0055] 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.

[0056] Oxy C 2-4 Polymer compounds having a repeating structure of alkylene units also include those classified as surfactants (more specifically, nonionic surfactants).

[0057] 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.

[0058] As copolymers, different oxy C 2-4 The copolymer may be a block copolymer.

[0059] The polyol may be any of aliphatic polyols, alicyclic polyols, aromatic polyols, and heterocyclic polyols. From the viewpoint of facilitating thin spreading of the polymer compound on the lead surface, aliphatic polyols and alicyclic polyols (e.g., polyhydroxycyclohexane, polyhydroxynorbornane, etc.) are preferred, and aliphatic polyols are particularly preferred. Examples of aliphatic polyols include aliphatic diols and polyols with triols or more (e.g., glycerin, trimethylolpropane, pentaerythritol, sugars or sugar alcohols, etc.). Examples of aliphatic diols include alkylene glycols with 5 or more carbon atoms. Examples of alkylene glycols include C 5~14 Alkylene glycol or C 5-10 The sugar alcohol may be, for example, erythritol, xylitol, mannitol, sorbitol, etc. The sugar or sugar alcohol may have either a chain structure or a cyclic structure. In the polyalkylene oxide adduct of polyol, the alkylene oxide is an oxy-C of the polymer compound. 2-4 Corresponding to an alkylene unit, at least C 2-4The 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.

[0060] 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.

[0061] 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.

[0062] organic group R 2 and R 3Each 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.

[0063] Examples of aromatic hydrocarbon groups include aromatic hydrocarbon groups having 24 or less carbon atoms (e.g., 6 to 24). The number of carbon atoms in the aromatic hydrocarbon group may be 20 or less (e.g., 6 to 20), 14 or less (e.g., 6 to 14), or 12 or less (e.g., 6 to 12). Examples of aromatic hydrocarbon groups include aryl groups and bisaryl groups. Examples of aryl groups include phenyl groups and naphthyl groups. Examples of bisaryl groups include monovalent groups corresponding to bisarenes. Examples of bisarenes include biphenyl and bisarylalkanes (e.g., bisC 6-10 Aryl C 1-4 Alkanes (such as 2,2-bisphenylpropane) are examples.

[0064] 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.

[0065] 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.

[0066] Examples of alicyclic hydrocarbon groups include cycloalkyl groups (cyclopentyl, cyclohexyl, cyclooctyl, etc.), cycloalkenyl groups (cyclohexenyl, cyclooctenyl, etc.), etc. Alicyclic hydrocarbon groups also include hydrogenated products of the above aromatic hydrocarbon groups.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] Among polymer compounds, oxy C 2-4 Ethers of hydroxy compounds with repeating alkylene units and oxy-C 2-4 The use of at least one selected from the group consisting of esters of hydroxy compounds having a repeating alkylene unit structure is preferred because it can suppress the amount of electricity during overcharge and further enhance the effect of suppressing the decrease in charge acceptance. Among such polymer compounds, a polymer compound having a repeating oxypropylene unit structure or a polymer compound having a repeating oxyethylene unit structure is preferred.

[0072] 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), groups having 8 or more carbon atoms, preferably 12 or more, and more preferably 16 or more. Among these, polymer compounds having long-chain aliphatic hydrocarbon groups are preferred because they are less likely to cause excessive adsorption to lead and further enhance the effect of suppressing a decrease in charge acceptance. The polymer compound may have at least one hydrophobic group that 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.

[0073] 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.

[0074] Among polymer compounds, those 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 enhancing the effect of suppressing a decrease in charge acceptance while reducing the amount of electricity during overcharge. Such polymer compounds can ensure high adsorption to lead even when they have a relatively low molecular weight (e.g., Mn of 1000 or less).

[0075] 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.

[0076] 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.

[0077] 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, but 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 can ensure higher charge acceptance and significantly reduce the amount of electricity during overcharge. In addition, these compounds are preferred because they significantly improve low-temperature high-rate discharge performance.

[0078] Among polymer compounds, those classified as surfactants preferably have an HLB of 4 or more, more preferably 4.3 or more, from the viewpoint of further reducing the amount of electrolyte loss. From the viewpoint of easily ensuring higher charge acceptance, the HLB of the polymer compound is preferably 18 or less, more preferably 10 or less or 9 or less, and even more preferably 8.5 or less.

[0079] The HLB of the polymer compound may be 4 or more (or 4.3 or more) and 18 or less, or 4 or more (or 4.3 or more) and 10 or less. From the viewpoint of achieving an excellent balance between reducing the amount of electricity in overcharge and improving charge acceptance, the HLB of the polymer compound is preferably 4 or more (or 4.3 or more) and 9 or less, or 4 or more (or 4.3 or more) and 8.5 or less.

[0080] Oxy C is more effective in reducing the amount of overcharge electricity and is easier to secure higher charge acceptance. 2-4 It is also preferable that the repeating structure of alkylene contains at least a repeating structure of an oxypropylene unit. In this case, the charge acceptance tends to be lower than that of a repeating structure of an oxyethylene unit, but even in this case, high charge acceptance can be ensured while suppressing the amount of gas generation to a low level. The polymer compound containing the oxypropylene unit is 1 In the chemical shift of the H-NMR spectrum, peaks due to -CH< and -CH2- of the oxypropylene unit are present in the range of 3.2 ppm to 3.8 ppm. The peaks are split due to differences in electron density around the nuclei of the hydrogen atoms in these groups. Such polymer compounds are 1 In the chemical shift of the H-NMR spectrum, for example, there are peaks in the range of 3.2 ppm to 3.42 ppm and in the range of more than 3.42 ppm to 3.8 ppm. The peak in the range of 3.2 ppm to 3.42 ppm is derived from -CH2-, and the peak in the range of more than 3.42 ppm to 3.8 ppm is derived from -CH< and -CH2-.

[0081] 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). 2-4Examples 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).

[0082] 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), polyoxyethylene-polyoxypropylene alkyl ethers (such as alkyl ethers (butyl ethers) in which the above R2 is an alkyl having 10 or less carbon atoms (or 8 or less or 6 or less) carbon atoms), polypropylene glycol carboxylate (such as the above R2), 3 Examples of the polymer compound include, but are not limited to, 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).

[0083] 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, or may be 75 mol% or less, or may be 60 mol% or less.

[0084] In a polymer compound containing a repeating structure of oxypropylene units, the proportion of oxypropylene units may be 5 mol% or more and 100 mol% or less (or 90 mol% or less), 10 mol% or more and 100 mol% or less (or 90 mol% or less), 20 mol% or more and 100 mol% or less (or 90 mol% or less), 5 mol% or more and 75 mol% or less (or 60 mol% or less), 10 mol% or more and 75 mol% or less (or 60 mol% or less), or 20 mol% or more and 75 mol% or less (or 60 mol% or less).

[0085] 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 the overcharge quantity of electricity and easily ensuring higher charge acceptance, the above proportion is preferably 85% or more, and more preferably 90% or more. For example, when a polymer compound has an -OH group at its terminal and also has a -CH2- group or a -CH< group bonded to the oxygen atom of the -OH group, 1In the H-NMR spectrum, the peaks of the hydrogen atoms of the -CH2- group and -CH< group have chemical shifts in the range of more than 3.8 ppm to 4.0 ppm.

[0086] The negative electrode material may contain one type of polymer compound or two or more types of polymer compounds.

[0087] The polymer compound may include, for example, a compound with an Mn of 5 million or less, a compound with an Mn of 3 million or less, or a compound with an Mn of 2 million or less, a compound with an Mn of 500,000 or less, or a compound with an Mn of 10,000 or less. From the viewpoint of ensuring higher charge acceptance by reducing the thickness of the polymer compound coating on the surfaces of lead and lead sulfate, the polymer compound preferably includes a compound with an Mn of 10,000 or less, a compound with an Mn of 5,000 or less, or a compound with an Mn of 4,000 or less, or a compound with an Mn of 3,000 or less, or a compound with an Mn of 2,500 or less. From the viewpoint of facilitating coating of the lead surface with the polymer compound and reducing the amount of gas generation, the Mn of such a compound may be 300 or more, 400 or more, or even 500 or more. From the viewpoint of further enhancing the effect of reducing the amount of gas generation, the Mn of such a compound is preferably 1,000 or more, more preferably 1,500 or more, or 1,800 or more. Two or more compounds with different Mn may be used as the polymer compound. That is, the polymer compound may have multiple Mn peaks in the molecular weight distribution.

[0088] 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 reducing the overcharge quantity of electricity and improving low-temperature high-rate discharge characteristics, the content of the polymer compound in the negative electrode material is preferably 20 ppm or more, and more preferably 30 ppm or more, by mass. From the viewpoint of maintaining high charge acceptance, the content of the polymer compound in the negative electrode material may be 600 ppm or less, and preferably 500 ppm or less or 400 ppm or less, by mass.

[0089] The content (by mass) of the polymer compound in the negative electrode material may be 8 ppm or more (or 10 ppm or more) and 600 ppm or less, 8 ppm or more (or 10 ppm or more) and 500 ppm or less, 8 ppm or more (or 10 ppm or more) and 400 ppm or less, 20 ppm or more (or 30 ppm or more) and 600 ppm or less, 20 ppm or more (or 30 ppm or more) and 500 ppm or less, or 20 ppm or more (or 30 ppm or more) and 400 ppm or less.

[0090] (organic shrinkage preventer) Organic shrink-preventing agents are generally broadly classified into lignin compounds and synthetic organic shrink-preventing agents. Synthetic organic shrink-preventing agents can also be considered to be organic shrink-preventing agents other than lignin compounds. Examples of organic shrink-preventing agents contained in the negative electrode material include lignin compounds and synthetic organic shrink-preventing agents. The negative electrode material may contain one type of organic shrink-preventing agent or two or more types of organic shrink-preventing agents.

[0091] Examples of lignin compounds include lignin and lignin derivatives, such as lignin sulfonic acid and its salts (alkali metal salts (sodium salts, etc.)).

[0092] Synthetic organic shrink-proofing agents are organic polymers containing sulfur, and generally contain multiple aromatic rings in the molecule and sulfur as sulfur-containing groups. Among the sulfur-containing groups, sulfonic acid groups or sulfonyl groups, which are stable, are preferred. The sulfonic acid groups may exist in either an acid form or a salt form such as a sodium salt.

[0093] As the organic shrink-preventing agent, it is also 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.

[0094] 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).

[0095] 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.

[0096] The condensate preferably contains at least a unit of an aromatic compound having a sulfur-containing group. In particular, using a condensate containing at least a unit of a bisphenol compound having a sulfur-containing group is advantageous in ensuring higher charge acceptance. From the viewpoint of enhancing the effect of reducing the amount of electricity during overcharge, it is also preferable to use a condensate of an aldehyde compound with a naphthalene compound having a sulfur-containing group and at least one selected from the group consisting of a hydroxyl group and an amino group.

[0097] 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.

[0098] 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.

[0099] The content of the organic shrinkage inhibitor in the negative electrode material is, for example, 0.005% by mass or more, and may be 0.01% by mass or more. When the content of the organic shrinkage inhibitor is in this range, a high low-temperature high-rate discharge capacity can be ensured. The content of the organic shrinkage inhibitor is, for example, 1.0% by mass or less, and may be 0.5% by mass or less. From the viewpoint of further enhancing the effect of suppressing a decrease in charge acceptance, the content of the organic shrinkage inhibitor is preferably 0.3% by mass or less, more preferably 0.25% by mass or less, even more preferably 0.2% by mass or less or 0.15% by mass or less, and may be 0.12% by mass or less.

[0100] The content of the organic shrinkage preventer in the negative electrode material may be 0.005% by mass or more (or 0.01% by mass or more) to 1.0% by mass or less, 0.005% by mass or more (or 0.01% by mass or more) to 0.5% by mass or less, 0.005% by mass or more (or 0.01% by mass or more) to 0.3% by mass or less, 0.005% by mass or more (or 0.01% by mass or more) to 0.25% by mass or less, 0.005% by mass or more (or 0.01% by mass or more) to 0.2% by mass or less, 0.005% by mass or more (or 0.01% by mass or more) to 0.15% by mass or less, or 0.005% by mass or more (or 0.01% by mass or more) to 0.12% by mass or less.

[0101] (carbonaceous material) The negative electrode material includes a carbonaceous material. Carbon black is preferably used as the carbonaceous material. Examples of carbon black include acetylene black, furnace black, and lamp black. Furnace black also includes Ketjen Black (trade name).

[0102] The negative electrode material may contain a carbonaceous material other than carbon black. Examples of the carbonaceous material include graphite, hard carbon, and soft carbon. The graphite may be any carbonaceous material having a graphite-type crystal structure, and may be either artificial graphite or natural graphite. The negative electrode material may contain one or more carbonaceous materials.

[0103] The content of the carbonaceous material (including carbon black) in the negative electrode material is 0.3 mass% or more, or 0.9 mass% or more, or may be 1.5 mass% or more, and may be, for example, 5 mass% or less, 3 mass% or less, or 2.1 mass% or less.

[0104] The content of the carbonaceous material in the negative electrode material may be 0.9% by mass or more and 5% by mass or less, 0.9% by mass or more and 3% by mass or less, 0.9% by mass or more and 2.1% by mass or less, or 1.5% by mass or more and 2.1% by mass or less (or 0.9% by mass or more and 3% by mass or less).

[0105] (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.

[0106] 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.

[0107] (Measurement of bulk density of negative electrode material and analysis of negative electrode material or constituents) The following describes the method for measuring the bulk density of negative electrode material and the method for analyzing the negative electrode material or its constituents. Prior to measurement or analysis, a fully charged lead-acid battery is disassembled to obtain 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 negative electrode surface and no color change is confirmed. However, the washing time should be within two hours. The washed negative electrode plate is dried under reduced pressure at 60±5°C for approximately six hours. If an adhesive material is present on the negative electrode plate after drying, it is removed by peeling. Next, the negative electrode material is separated from the negative electrode plate to obtain a sample (hereinafter referred to as Sample A). Sample A is then crushed as necessary and subjected to analysis.

[0108] (1) Measurement of bulk density of negative electrode material The bulk density of unpulverized sample A is determined by mercury intrusion porosimetry using a mercury porosimeter. More specifically, a predetermined amount of unpulverized sample A is first collected and its mass is measured. This sample A is placed in a measurement vessel of the mercury porosimeter, which is evacuated under reduced pressure. Then, the vessel is filled with mercury at a pressure of 0.5 psia to 0.55 psia (≒ 3.45 kPa to 3.79 kPa). The bulk volume of sample A is measured, and the bulk density of the negative electrode material is determined by dividing the measured mass of sample A by the bulk volume. The bulk volume is the volume of the measurement vessel minus the volume of the mercury injected. An automatic porosimeter (Autopore IV9505) manufactured by Shimadzu Corporation is used as the mercury porosimeter.

[0109] (2) Analysis of polymer compounds (2-1) Qualitative analysis of polymer compounds (a) Oxy C 2-4 Alkylene unit analysis Pulverized sample A is used. 150.0±0.1 mL of chloroform is added to 100.0±0.1 g of sample A, and the mixture is stirred at 20±5°C for 16 hours to extract the polymer compound. 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.

[0110] 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 C2-4 Identify the type of alkylene unit.

[0111] 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

[0112] 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.

[0113] 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.

[0114] (b) Analysis of hydrophobic groups in esterified products When the polymer compound is an ester of a hydroxy compound, a predetermined amount of the polymer compound obtained by extracting and dissolving the chloroform solution containing the polymer compound in solution in (a) above is collected and an aqueous potassium hydroxide solution is added. This saponifies the ester, producing a fatty acid potassium salt and a hydroxy compound. The aqueous potassium solution is added until saponification is complete. A solution of methanol and boron trifluoride is added to the resulting mixture and mixed to convert the fatty acid potassium salt into a fatty acid methyl ester. The resulting mixture is analyzed by pyrolysis GC-MS under the following conditions to identify the hydrophobic groups contained in the ester. Analytical equipment: Shimadzu Corporation, high-performance general-purpose gas chromatogram GC-2014 Column: DEGS (diethylene glycol succinate) 2.1 m Oven temperature: 180~120℃ Inlet temperature: 240℃ Detector temperature: 240℃ Carrier gas: He (flow rate: 50 mL / min) Injection volume: 1μL~2μL

[0115] (c) Analysis of hydrophobic groups in etherified products When the polymer compound is an etherified product of a hydroxy compound, a predetermined amount of the polymer compound obtained by the extraction in (a) above is collected and hydrogen iodide is added to the polymer compound, which is obtained by drying the chloroform solution in which the polymer compound is dissolved. 3 ) corresponding to the iodide (R 3 I) is produced, and oxy C 2-4 Diiodo C corresponding to the alkylene unit 2-4 Alkanes are produced. The hydrogen iodide mentioned above is converted into etherified iodides and diiodo C. 2-4 The amount of ether added is sufficient to complete the conversion to an alkane. The resulting mixture is analyzed by pyrolysis GC-MS under the same conditions as in (b) above, and the hydrophobic groups contained in the etherified product are identified.

[0116] (2-2) Quantitative analysis of polymer compounds The appropriate amount of the chloroform soluble matter was measured with an accuracy of ±0.0001 g. r (g) Dissolve in deuterated chloroform together with tetrachloroethane (TCE), 1 Measure the H-NMR spectrum. The integral value (S a ) and the integral value of the peak due to TCE (S r ) and calculate the mass-based content C of the polymer compound in the negative electrode material from the following formula: n Calculate the ppm.

[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 aand M a is the N of each monomer unit a Value and M a The value is an average value obtained by using the molar ratio (mol %) of each monomer unit contained in the repeating structure.

[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] (2-3) 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°C ± 1°C Mobile phase: tetrahydrofuran Flow rate: 1mL / min. Concentration: 0.20% by mass Injection volume: 10μL Standard substance: polyethylene glycol (Mn = 2,000,000, 200,000, 20,000, 2,000, 200) Detector: Differential refractive index detector (Shodex RI-201H)

[0122] (3) Analysis of organic shrinkage inhibitors (3-1) Qualitative analysis of organic shrinkage inhibitors in negative electrode materials The crushed 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 (hereafter 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 or the like which can provide information on the individual compounds that make up the substance.

[0124] (3-2) Quantitative determination of the content of organic shrinkage inhibitor in negative electrode material As in (3-1) above, for each of the separated products containing the organic shrinkage inhibitor, insoluble components are removed by filtration to obtain a solution. The ultraviolet-visible absorption spectrum of each of the obtained solutions is measured. The content of each organic shrinkage inhibitor in the negative electrode material is determined using the intensity of the peak characteristic of each organic shrinkage inhibitor and a previously prepared calibration curve.

[0125] When obtaining a lead-acid battery with an unknown content of organic shrinkage preventer and measuring the content of the organic shrinkage preventer, it may be impossible to precisely identify the structural formula of the organic shrinkage preventer, and therefore the same organic shrinkage preventer cannot be used for the calibration curve. In this case, a calibration curve is created using a separately available organic polymer that shows similar shapes in the ultraviolet-visible absorption spectrum, infrared spectroscopy spectrum, NMR spectrum, etc. to the organic shrinkage preventer extracted from the negative electrode of the battery, and the content of the organic shrinkage preventer is measured using the ultraviolet-visible absorption spectrum.

[0126] (4) Quantitative analysis of carbonaceous materials and barium sulfate 50 mL of 20% by mass nitric acid was added to 10 g of crushed 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 separate out the carbonaceous material, barium sulfate, and other solids.

[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 can be used. A paste type positive electrode plate includes a positive electrode current collector and a positive electrode material. The configuration of a clad type positive electrode plate is as described above.

[0131] The positive 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 positive electrode current collector because it is easy to support the positive electrode material.

[0132] As the lead alloy used for the positive electrode current collector, a Pb-Sb alloy, a Pb-Ca alloy, or a Pb-Ca-Sn alloy is preferred in terms of corrosion resistance and mechanical strength. The positive electrode current collector may have a surface layer. The surface layer and the inner layer of the positive electrode current collector may have different compositions. The surface layer may be formed on a part of the positive electrode current collector. The surface layer may be formed only on the grid portion, the lug portion, or the frame portion of the positive electrode current collector.

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

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

[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 preferably is mainly composed of a polymer component. The polymer component is preferably polyolefin (polyethylene, polypropylene, etc.). The pore-forming agent can be at least one selected from the group consisting of polymer powder and oil.

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

[0141] (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.

[0142] The electrolytic solution may contain cations (e.g., metal cations) and / or anions (e.g., anions other than sulfate anions (e.g., phosphate ions)) as needed. Examples of metal cations include at least one selected from the group consisting of Na ions, Li ions, Mg ions, and Al ions.

[0143] 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.

[0144] 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.

[0145] (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.

[0146] The electrode plate assembly may include one or more negative electrode plates. When the electrode plate assembly includes two or more negative electrode plates, if the negative electrode material of at least one negative electrode plate contains carbon black in the above-described content and the negative electrode current collector is roughened to the above-described surface roughness Ra range, shedding of the negative electrode active material can be suppressed for this negative electrode plate, achieving a long life. Furthermore, the longer the life, the easier it is to achieve this, depending on the number of such negative electrode plates. Furthermore, if the negative electrode material of at least one negative electrode plate contains a polymer compound, the low-temperature high-rate discharge characteristics of this negative electrode plate can be improved, and the low-temperature high-rate discharge characteristics can be further improved depending on the number of such negative electrode plates. From the viewpoint of suppressing shedding of the negative electrode active material and achieving a long life and / or improving the high-rate discharge characteristics, it is preferable that 50% or more (more preferably 80% or more or 90% or more) of the negative electrode plates included in the electrode plate assembly satisfy the above conditions. The ratio of negative electrode plates contained in the electrode plate group that satisfy the above conditions is 100% or less. All of the negative electrode plates contained in the electrode plate group may satisfy the above conditions.

[0147] When a lead-acid battery has two or more cells, it is sufficient that the electrode plate assemblies of at least some of the cells include negative electrode plates that satisfy the above conditions. From the viewpoint of suppressing the detachment of negative electrode active material and realizing a long life, and / or from the viewpoint of improving high-rate discharge characteristics, it is preferable that 50% or more (more preferably 80% or more or 90% or more) of the number of cells included in the lead-acid battery include electrode plate assemblies that include negative electrode plates that satisfy the above conditions. Of the cells included in the lead-acid battery, the proportion of cells that include electrode plate assemblies that include negative electrode plates that satisfy the above conditions is 100% or less. It is preferable that all of the electrode plate assemblies included in the lead-acid battery include negative electrode plates that satisfy the above conditions.

[0148] 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.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] In this specification, the performance of a lead-acid battery is evaluated according to the following procedure: The test battery used for evaluation has a rated voltage of 2 V / cell and a rated 5-hour rate capacity of 32 Ah.

[0153] (a) PSOC cycle life The test is carried out using a test battery under the following conditions. At 25°C, the test battery is charged at a constant voltage of 2.4 V / cell, then discharged at a constant current (A) 0.2 times the value specified for the rated capacity (Ah) until the test battery's depth of discharge (DOD) reaches 10%. Next, the following discharge 1 and charge 1 cycle are repeated until the end-of-discharge voltage falls to 1.75 V / cell or less. The number of cycles when the end-of-discharge voltage falls to 1.75 V / cell or less is evaluated as the PSOC cycle number.

[0154] Discharge 1: Discharge for 30 seconds at a current (A) twice the value indicated on the rated capacity (Ah). Charging 1: Charge for 1 minute at the current (A) indicated for the rated capacity (Ah).

[0155] After the test, the battery was disassembled and the electrode material that had fallen off to the bottom of the battery container was removed. The electrode material was washed with water, dried, and the mass (g / cell) of the fallen electrode material was measured. At this time, the condition of the positive and negative electrode plates was visually inspected to determine whether the fallen electrode material was derived from the positive electrode material or the negative electrode material.

[0156] (b) Low-temperature high-rate discharge performance The test is carried out in accordance with JIS D 5301:2006 under the following conditions: The test battery is charged at a constant current (A) of 0.2 times the rated capacity (Ah). Charging is continued until the terminal voltage or temperature-converted electrolyte density measured every 15 minutes during charging shows a constant value for three consecutive times. The test battery is then placed in an environment of -15°C ± 1°C for at least 16 hours. The test battery is then discharged at a constant current (A) of 0.2 times the rated capacity (Ah) at -15°C. The time until the end-of-discharge current drops below 1.0 V / cell is measured and evaluated as the low-temperature high-rate duration.

[0157] A lead-acid battery according to one aspect of the present invention will be summarized below.

[0158] (1) A lead-acid battery, The lead-acid battery includes a negative electrode plate, a positive electrode plate, and an electrolyte, The negative electrode plate includes a negative electrode current collector and a negative electrode material, the negative electrode material includes a carbonaceous material, the content of the carbonaceous material in the negative electrode material is 0.9% by mass or more, The negative electrode current collector has a surface with an arithmetic mean roughness Ra of 1 μm or more and 22 μm or less.

[0159] (2) In the above (1), the density of the negative electrode material is 3.4 g / cm 3 It may be more than that.

[0160] (3) In the above (2), the density of the negative electrode material is 4.1 g / cm 3 or less than 3.8g / cm 3 That is, the density of the negative electrode material may be 3.4 g / cm 3 More than 4.1g / cm 3 or less than 3.4g / cm 3 More than 3.8g / cm 3 may be.

[0161] (4) In any one of the above (1) to (3), the arithmetic mean roughness Ra of the surface of the negative electrode current collector may be 15 μm or less or 10 μm or less.

[0162] (5) In any one of the above (1) to (4), the arithmetic mean roughness Ra of the surface of the negative electrode current collector may be 1 μm or more and 15 μm or less, 1 μm or more and 10 μm or less, 2 μm or more and 15 μm or less, 2 μm or more and 10 μm or less, 4 μm or more and 15 μm or less, or 4 μm or more and 10 μm or less.

[0163] (6) In any one of the above (1) to (5), the negative electrode current collector may be a punched current collector.

[0164] (7) In any one of the above (1) to (6), the content of the carbonaceous material in the negative electrode material may be 1.5 mass % or more.

[0165] (8) In any one of the above (1) to (7), the content of the carbonaceous material in the negative electrode material may be 5% by mass or less, 3% by mass or less, or 2.1% by mass or less.

[0166] (9) In any one of the above (1) to (8), the negative electrode material is measured using deuterated chloroform as a solvent. 1 The polymer compound may contain a peak in the range of 3.2 ppm to 3.8 ppm in the chemical shift of the H-NMR spectrum.

[0167] (10) A lead-acid battery, The lead-acid battery includes a negative electrode plate, a positive electrode plate, and an electrolyte, The negative electrode plate includes a negative electrode current collector and a negative electrode material, the negative electrode material includes a carbonaceous material, the content of the carbonaceous material in the negative electrode material is 0.3 mass% or more, 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.

[0168] (11) In the above (9) or (10), 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 1In 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 50% or more, 80% or more, 85% or more, or 90% or more.

[0169] (12) In any one of the above (9) to (11), the polymer compound is oxy C 2-4 It may contain a repeating structure of alkylene units.

[0170] (13) In any one of the above (9) to (12), the polymer compound may include a compound having an Mn of 5 million or less, 3 million or less, 2 million or less, 500,000 or less, 100,000 or less, 50,000 or less, 20,000 or less, 10,000 or less, 5,000 or less, 4,000 or less, 3,000 or less, or 2,500 or less.

[0171] (14) In any one of the above (9) to (13), the polymer compound may include a compound having an Mn of 300 or more, 400 or more, 500 or more, 1000 or more, 1500 or more, or 1800 or more.

[0172] (15) In any one of the above (9) to (14), the polymer compound is 2-4 The polymer 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 polyC 2-4 It may be at least one selected from the group consisting of alkylene oxide adducts.

[0173] (16) In the above (15), the polymer compound may contain at least one selected from the group consisting of polyethylene glycol oleate, polyethylene glycol dilaurate, polyethylene glycol distearate, and polyethylene glycol dioleate.

[0174] (17) In any one of the above (9) to (16), the content of the polymer compound in the negative electrode material may be 30 ppm or more and 600 ppm or less by mass.

[0175] (18) In any one of the above (9) to (17), the content of the carbonaceous material in the negative electrode material may be 0.9 mass % or more or 1.5 mass % or more.

[0176] (19) In any one of the above (9) to (18), the content of the carbonaceous material in the negative electrode material may be 5 mass % or less, 3 mass % or less, or 2.1 mass % or less.

[0177] (20) In any one of the above (1) to (19), the carbonaceous material may contain carbon black.

[0178] [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.

[0179] 《Lead acid batteries A1~A39, B1~B8》 (1) Preparation of lead-acid batteries (a) Preparation of the negative electrode plate Prepare a punched current collector made of a Pb-Ca-Sn alloy. If necessary, press the surfaces of the vertical and horizontal bones of the current collector into a predetermined mold to obtain a negative electrode current collector with a surface roughness equal to the arithmetic mean surface roughness Ra shown in Table 1 or Table 2.

[0180] Next, the raw materials, lead powder, barium sulfate, carbon black, and sodium lignin sulfonate as an organic shrinkage preventer are mixed with an appropriate amount of sulfuric acid aqueous solution to obtain a negative electrode paste. The components are mixed so that the carbon black content in the negative electrode material, determined by the procedures described above, is the value shown in Table 1 or Table 2, the organic shrinkage preventer content is 0.1 mass%, and the barium sulfate content is 0.4 mass%. The concentration and amount of sulfuric acid aqueous solution are also adjusted so that the density (bulk density) of the negative electrode material, determined by the procedures described above, for a lead-acid battery fully charged after chemical formation, is the value shown in Table 1 or Table 2. The negative electrode paste is filled into the mesh portion of a punched current collector, aged, and dried to obtain an unformed negative electrode plate.

[0181] (b) Preparation of the positive electrode plate The raw lead powder is mixed with an aqueous sulfuric acid solution to obtain a positive electrode paste. A punched current collector made of a Pb-Ca-Sn alloy is prepared. The positive electrode paste is filled into the mesh of the punched current collector, which is then aged and dried to obtain an unformed positive electrode plate.

[0182] (c) Preparation of test battery The test battery has a rated voltage of 2V / cell and a rated 5-hour rate capacity of 32Ah. The test battery's electrode plate assembly consists of seven positive and seven negative plates. The negative plates are housed in a pouch-shaped separator made of a microporous polyethylene film and are stacked alternately with the positive plates to form an electrode plate assembly. The electrode plate assembly is housed in a polypropylene battery case together with an electrolyte (aqueous sulfuric acid solution), and chemical formation is carried out inside the case to create a liquid lead-acid battery. The specific gravity of the electrolyte in a fully charged lead-acid battery at 20°C is 1.28.

[0183] In this way, batteries A1 to A39 (Examples or Comparative Examples) and B1 to B8 (Reference Examples) were produced, each having a different combination of the density of the negative electrode material, the carbon black content in the negative electrode material, and / or the arithmetic mean surface roughness Ra of the surface of the negative electrode current collector, and were evaluated as described below.

[0184] 《Lead acid battery C1~C32》 To prepare the negative electrode plate, lead powder, barium sulfate, carbon black, polyethylene glycol oleate (PEG / OL) (Mn500) as a polymer compound, and sodium lignosulfonate as an organic shrinkage preventer were mixed with an appropriate amount of sulfuric acid solution to obtain a negative electrode paste. The components were mixed so that the carbon black content in the negative electrode material, determined by the procedure described above, was the value shown in Table 3, the polymer compound content was 0.025% by mass (250 ppm), the organic shrinkage preventer content was 0.1% by mass, and the barium sulfate content was 0.4% by mass. The concentration and amount of sulfuric acid solution were also adjusted so that the density (bulk density) of the negative electrode material, determined by the procedure described above for a fully charged lead-acid battery after chemical formation, was the value shown in Table 3. The negative electrode paste was filled into the mesh portion of a punched current collector and aged and dried to obtain an unformed negative electrode plate. Other than this, batteries C1 to C32 (Examples) were obtained in the same manner as batteries A1 to A39 and evaluated in the same manner.

[0185] 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 3.6 ppm to 4.3 ppm. When the polymer compound has a repeating structure of oxypropylene units, the peak of the polymer compound measured by the above-mentioned procedure 1 In the H-NMR spectrum, a peak derived from --CH2- of the oxypropylene unit is 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 percentage of the integral of the peak between 3.2 ppm and 3.8 ppm to the sum of the 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 is 96.21 to 99.99%.

[0186] 《Lead acid batteries D1~D8》 In preparing the negative electrode plate, raw materials lead powder, barium sulfate, carbon black, a polymer compound shown in Table 4, and sodium lignin sulfonate as an organic shrinkage preventer are mixed with an appropriate amount of aqueous sulfuric acid solution to obtain a negative electrode paste. At this time, the polymer compound is mixed into the negative electrode paste so that the content of the polymer compound in the negative electrode material obtained by the above-mentioned procedure becomes the content shown in Table 4. Other than this, the same procedures as for battery C32 were carried out to obtain batteries D1 to D8 (Examples), which were then evaluated in the same manner.

[0187] In Table 4, PEG is polyethylene glycol (Mn 500), PEG / OL is polyethylene glycol oleate (Mn 500), PEG / DL is polyethylene glycol dilaurate (Mn 630), PEG / DS is polyethylene glycol distearate (Mn 820), and PPG is polypropylene glycol (Mn 2000).

[0188] (2) Evaluation (a) PSOC cycle life Using the test batteries, the number of PSOC cycles is measured according to the procedure described above. The PSOC life characteristics of each lead-acid battery are evaluated based on the ratio of the number of PSOC cycles of the lead-acid battery A1, which is set to 100. After the test, the batteries were disassembled to measure the amount of electrode material that had fallen off. The amount of electrode material that had fallen off for each battery was evaluated based on the ratio of the amount of electrode material that had fallen off for battery A9, which was set at 100.

[0189] (b) Low-temperature high-rate discharge performance Using the test batteries, the low-temperature high-rate duration was measured using the procedure described above. The low-temperature high-rate discharge performance of each lead-acid battery was evaluated as a ratio to the duration of lead-acid battery A1, which was set at 100.

[0190] The results are shown in Tables 1 and 2. In Table 1, group G1 consisting of batteries A1 to A13, group G2 consisting of batteries A14 to A26, and group G3 consisting of batteries A27 to A39 differ in the carbon black content in the negative electrode material, so a simple comparison cannot be made. Batteries A1 to A4 and A13 are comparative examples for Examples A5 to A12. Batteries A14 to A17 and A26 are comparative examples for Examples A5 to A12. Batteries A27 to A30 and A39 are comparative examples for Examples A31 to A38.

[0191] As shown in Table 2, in batteries B1 to B8 in which the carbon black content in the negative electrode material was 0.3 mass %, the amount of electrode material that fell off was extremely small, and the falling off of the electrode material did not become a factor in shortening the life.

[0192] As shown in Table 1, comparing Group G1 (batteries A1 to A13) with a carbon black content of 0.9% by mass, Group G2 (batteries A4 to A26) with a carbon black content of 1.5% by mass, and Group G3 (batteries A27 to A39) with a carbon black content of 2.1% by mass, we see that increasing the carbon black content in the negative electrode material leads to a greater number of PSOC cycles and improved PSOC life characteristics. On the other hand, the amount of electrode material loss is significantly greater in these groups than in B1 to B8. Judging from the state of the positive and negative plates after the test, the electrode material loss occurred in the negative electrode. This suggests that as the amount of carbon black increases, the factor that shortens the life of lead-acid batteries shifts to the loss of negative electrode material.

[0193] However, as shown in Table 1, by roughening the negative electrode current collector and setting the arithmetic mean roughness Ra of the surface of the negative electrode current collector to 1 μm or more, the adhesion between the negative electrode current collector and the negative electrode material is improved, and the detachment of the negative electrode material is suppressed. As a result, when the carbon black content is increased to 0.9 mass% or more, the PSOC life characteristics are further improved.

[0194] In group G3, as shown by batteries A27 to A35, increasing the density of the negative electrode material reduces the amount of shed negative electrode material. However, in battery A30, which has a negative electrode current collector with a surface roughness Ra of less than 1 μm, increasing the density of the negative electrode material reduces the amount of shed negative electrode material to 90% of the amount of shed negative electrode material in battery A27, but the reduction is small. In contrast, in battery A35, which has a negative electrode current collector with a surface roughness Ra of 1 μm or more, increasing the density of the negative electrode material reduces the amount of shed negative electrode material to nearly 70% of the amount of shed negative electrode material in battery A27, a significant reduction. Furthermore, as a result, battery A35 achieves a significantly longer PSOC life.

[0195] Figure 2 is a graph showing the relationship between the surface roughness Ra of the negative electrode current collector and the amount of electrode material (negative electrode material) that fell off after the PSOC cycle test. In Figure 2, the amount of fallen off is shown as a relative value, with the amount of fallen off of Battery A9, which has a carbon black content of 0.9 mass% and a negative electrode current collector surface roughness Ra of 4.3 μm, taken as 100. Figure 2 shows that the amount of fallen off of the negative electrode material is largely independent of the carbon black content, and decreases significantly at surface roughness Ra of 1 μm or more.

[0196] Furthermore, Tables 1 and 2 show that the low-temperature high-rate discharge performance tends to decrease as the carbon black content increases. However, as shown in Tables 3 and 4, the addition of a polymer compound can restore the decreased low-temperature high-rate discharge performance. For example, batteries C25 to C32, which contain a large amount of carbon black (2.1 mass%), exhibit better low-temperature high-rate discharge performance than batteries B1 to B8, which do not contain an increased amount of carbon black, due to the addition of the polymer compound.

[0197] Comparing Battery B8 and Battery C8, when the carbon black content is 0.3 mass%, the improvement in low-temperature high-rate discharge performance due to the addition of the polymer compound is about 7.5%. In contrast, comparing Battery A35 and Battery C32, when the carbon black content is 2.1 mass%, the improvement in low-temperature high-rate discharge performance is about 10%. The higher the carbon black content, the greater the improvement in low-temperature high-rate discharge performance due to the addition of the polymer compound.

[0198] As shown in Table 4, when the amount of polymer compound added is changed from 0.025 mass% (250 ppm) or when the type of polymer compound is changed, a similarly large improvement in low-temperature high-rate discharge performance is obtained. In particular, when the amount of polymer compound added is in the range of 0.003 mass% (30 ppm) to 0.06 mass% (600 ppm), the improvement in low-temperature high-rate discharge performance is remarkable.

[0199] [Table 1]

[0200] [Table 2]

[0201] [Table 3]

[0202] [Table 4] [Industrial Applicability]

[0203] The lead-acid batteries according to one aspect and another aspect of the present invention are suitable for use in idle-stop vehicles, for example, as an IS lead-acid battery that is charged and discharged under PSOC conditions. Furthermore, the 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 uses are merely examples, and the present invention is not limited to these uses. [Explanation of symbols]

[0204] 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 a negative electrode plate, a positive electrode plate, and an electrolyte, The negative electrode plate includes a negative electrode current collector and a negative electrode material, the negative electrode material includes a carbonaceous material, the content of the carbonaceous material in the negative electrode material is 0.9% by mass or more and 5% by mass or less, The negative electrode current collector has a surface with an arithmetic mean roughness Ra of 1 μm or more and 22 μm or less.

2. 10. The lead-acid battery of claim 1, wherein the carbonaceous material comprises carbon black.

3. The density of the negative electrode material is 3.4 g / cm ３ The lead-acid battery according to claim 2 .

4. The density of the negative electrode material is 4.1 g / cm ３ 4. The lead-acid battery according to claim 3, wherein:

5. The lead acid battery according to any one of claims 1 to 4, wherein the arithmetic mean roughness Ra of the surface of the negative electrode current collector is 15 µm or less.

6. The lead acid battery according to any one of claims 1 to 5, wherein the negative electrode current collector is a punched current collector.

7. The negative electrode material is measured using deuterated chloroform as a solvent. １ The lead acid battery according to any one of claims 1 to 6, comprising a polymer compound having a peak in the range of 3.2 ppm to 3.8 ppm in chemical shift of a H-NMR spectrum.

8. The polymer compound is oxy C ２－４ The lead acid battery according to claim 7, comprising a repeating structure of alkylene units.

9. The polymer compound is oxy C ２－４ Hydroxy compounds having a repeating structure of alkylene units, etherified products of the hydroxy compounds, and etherified products of the hydroxy compounds and at least one selected from the group consisting of esters, The hydroxy compound is polyC ２－４ Alkylene glycol, oxy C ２－４ Copolymer containing repeating alkylene units and polyol polyC ２－４ The lead acid battery according to claim 7 or 8, wherein the compound is at least one selected from the group consisting of alkylene oxide adducts.

10. 10. The lead-acid battery according to claim 9, wherein the polymer compound comprises at least one selected from the group consisting of polyethylene glycol, polyethylene glycol oleate, polyethylene glycol dilaurate, polyethylene glycol distearate, and polypropylene glycol.

11. The lead acid battery according to any one of claims 7 to 10, wherein the content of the polymer compound in the negative electrode material is 30 ppm or more and 600 ppm or less by mass.

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