lead-acid batteries

Abstract

This product provides a lead-acid battery with improved PSOC cycle life and low-temperature HR performance. [Solution] The electrode plate group 11 comprises a positive electrode plate 3, a negative electrode plate 2, and a separator 4, and the extraction load (initial value) W1 when the electrode plate group of a fully charged lead-acid battery is pulled out of the battery case 12 is 1.8 times or more the weight W2 of the electrode plate group, and the positive electrode plate includes a positive electrode current collector and a positive electrode material, and at least the electrolyte and the positive electrode material contain phosphorus, and the value obtained by dividing the sum of the amount of phosphorus (mmol) contained in the electrolyte and the amount of phosphorus (mmol) contained in the positive electrode material by the volume (L) of the electrolyte is 8 mmol / L to 100 mmol / L, and the electrolyte contains metal cations, and the metal cations contain sodium ions, and the concentration of sodium ions in the electrolyte is 30 mmol / L or more, the lead-acid battery 1.

Description

[Technical Field]

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

[0002] Patent Document 1 proposes a lead-acid battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator, wherein the positive electrode has a positive electrode material containing a positive electrode active material, the negative electrode has a negative electrode material containing a negative electrode active material, and the electrolyte contains phosphate ions.

[0003] Patent Document 2 proposes a lead-acid battery characterized by having a positive electrode plate made of a material containing basic lead phosphate.

[0004] Patent Document 3 describes a current collector comprising: a battery case having a cell chamber; a group of electrode plates housed in the cell chamber; and an electrolyte injected into the cell chamber, wherein the group of electrode plates comprises a plurality of alternately arranged positive and negative electrode plates, and a separator disposed between the positive electrode plate and the negative electrode plate, and the positive electrode plate has a positive electrode current collector plate comprising a lattice-shaped substrate portion holding a positive electrode active material and a positive electrode mixture containing tin (Sn), and an ear portion continuous with the lattice-shaped substrate portion, wherein the positive electrode mixture comprises needle-shaped crystalline particles, and the needle-shaped crystalline particles are the positive electrode The invention proposes a lead-acid battery characterized by having a positive electrode compound formed on at least a portion of the plate surface, a tin (Sn) content of the positive electrode compound being 0.20% by weight or more and 0.90% by weight or less, and the electrolyte containing one or more of aluminum ions, lithium ions, sodium ions, and magnesium ions, with the total concentration of aluminum ions, lithium ions, sodium ions, and magnesium ions in the electrolyte being 0.010 mol / L or more and 0.30 mol / L or less.

[0005] Patent Document 4 proposes a sealed lead-acid battery equipped with a gel-like electrolyte, characterized in that a mat-like body with a thickness of 0.5 mm or more, mainly composed of glass long fibers or synthetic resin fibers with a diameter of 10 μm or more and a maximum pore diameter of 50 μm or less, an average pore diameter of 2 μm or more, and a sheet-like porous plate with a thickness of less than 0.5 mm, having a maximum pore diameter of 50 μm or less and an average pore diameter of 2 μm or more, and containing 15% by mass or less, is brought into contact with each other or integrated to form a separator; a gel-like electrolyte consisting of a small amount of soluble sulfate, phosphoric acid containing 0.75% by mass or more and 4.0% by mass, preferably 1.0% by mass or more and 3.0% by mass, and silica fine particles of less than 10% by mass, preferably 5.0% by mass or more and 8.0% by mass, is disposed in at least the pores of the separator and most of the cell space around the electrode plate group; the electrode plate group is formed by alternately stacking positive and negative electrode plates with a separator in between, and the positive electrode plate is pressed against the mat-like body of the separator.

[0006] Patent Document 5 proposes a lead-acid battery comprising a positive electrode and a negative electrode facing each other via a separator, and an electrolyte, wherein the separator has convex ribs and a base portion supporting the ribs, and contains polyolefin and silica, the height H of the ribs is 1 mm or less, the thickness T of the base portion is 0.05 mm or more, the electrolyte contains aluminum ions, and the concentration of aluminum ions in the electrolyte is 0.01 to 0.3 mol / L. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] International Publication No. 2016 / 121510 [Patent Document 2] Japanese Patent Application Publication No. 10-012225 [Patent Document 3] Japanese Patent Publication No. 2023-046379 [Patent Document 4] Japanese Patent Publication No. 2003-036831 [Patent Document 5] Japanese Patent Publication No. 2021-005574 [Overview of the project] [Problems that the invention aims to solve]

[0008] When lead-acid batteries are used in a partially charged state called PSOC (Partial State of Charge), stratification, a phenomenon in which differences in the concentration of sulfuric acid in the electrolyte occur, is likely to progress. When the electrolyte stratifies, the life performance of the lead-acid battery in charge-discharge cycle tests that simulate PSOC (hereinafter also referred to as "PSOC cycle life") decreases.

[0009] While Patent Document 1 proposes adding phosphoric acid to the electrolyte and Patent Document 2 proposes adding basic lead phosphate to the electrode active material, using more than a certain amount of phosphorus in a lead-acid battery may reduce its low-temperature high-rate (HR) performance. [Means for solving the problem]

[0010] One aspect of the present invention is a lead-acid battery comprising a group of electrode plates, an electrolyte, and a battery case containing the group of electrode plates and the electrolyte, wherein the group of electrode plates comprises a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, the pull-out load (initial value) W1 when the group of electrode plates of the fully charged lead-acid battery is pulled out of the battery case is 1.8 times or more the weight W2 of the group of electrode plates, and the positive electrode plate comprises a positive electrode current collector and a positive electrode material, and at least the electrolyte and the positive electrode material contain phosphorus The present invention relates to a lead-acid battery, wherein the sum of the amount of phosphorus (mmol) contained in the electrolyte and the amount of phosphorus (mmol) contained in the positive electrode material, divided by the volume (L) of the electrolyte, is 8 mmol / L to 100 mmol / L, the phosphorus contained in the electrolyte exists as anions derived from phosphoric acid, the electrolyte contains metal cations, the metal cations contain sodium ions, and the concentration of sodium ions in the electrolyte is 30 mmol / L or more. [Effects of the Invention]

[0011] The lead-acid battery according to the present invention suppresses stratification remarkably because the extraction load gradually increases during the charge-discharge cycle, so that the PSOC cycle life and the low-temperature HR performance are improved.

Brief Description of the Drawings

[0012] [Figure 1] It is a partially cutaway perspective view showing the appearance and internal structure of a lead-acid battery according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present disclosure will be described with examples, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values and materials may be exemplified, but other numerical values and materials may be applied as long as the effects of the present disclosure can be obtained. In this specification, the description "numerical value A to numerical value B" includes the numerical value A and the numerical value B and can be read as "not less than numerical value A and not more than numerical value B". In the following description, when the lower limit and the upper limit of a numerical value regarding a specific physical property or condition are exemplified, any combination of any of the exemplified lower limits and any of the exemplified upper limits can be made as long as the lower limit is not more than the upper limit. When a plurality of materials are exemplified, one of them may be selected and used alone, or two or more of them may be used in combination.

[0014] In addition, the present disclosure includes combinations of matters described in two or more claims arbitrarily selected from a plurality of claims described in the appended claims. That is, as long as no technical contradiction occurs, matters described in two or more claims arbitrarily selected from a plurality of claims described in the appended claims can be combined.

[0015] The lead-acid battery includes a positive electrode plate, a negative electrode plate, a separator interposed between the positive electrode plate and the negative electrode plate, and an electrolyte. The electrolyte contains sulfuric acid. Charging and discharging proceed by the movement of sulfate ions between the positive electrode plate and the negative electrode plate and the electrolyte. During discharging, sulfate ions move to the positive electrode plate and the negative electrode plate. During charging, sulfate ions move from the positive electrode plate and the negative electrode plate into the electrolyte.

[0016] The positive electrode plate, the negative electrode plate, and the separator constitute an electrode plate group. The electrode plate group and the electrolyte together constitute a cell. One electrode plate group constitutes one cell. A lead-acid battery includes one or more electrode groups and thus includes one or more cells. There is no particular limitation on the number of positive electrode plates and negative electrode plates included in one electrode plate group. The electrode plate group included in the lead-acid battery according to the present disclosure includes, for example, a total of 12 or more positive electrode plates and negative electrode plates. The plurality of electrode plate groups are usually accommodated in respective individual cell chambers and connected in series with each other.

[0017] The positive electrode plate includes a positive electrode current collector and a positive electrode electrode material. The positive electrode electrode material includes at least lead dioxide during charging and at least lead sulfate during discharging as a positive electrode active material that exhibits capacitance through an oxidation-reduction reaction.

[0018] The negative electrode plate includes a negative electrode current collector and a negative electrode electrode material. The negative electrode electrode material includes at least lead during charging and at least lead sulfate during discharging as a negative electrode active material that exhibits capacitance through an oxidation-reduction reaction.

[0019] (1) A lead-acid battery according to an embodiment of the present disclosure is a lead-acid battery comprising a group of plates, an electrolyte, and a battery case containing the group of plates and the electrolyte, wherein the group of plates comprises a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, the pull-out load (initial value) W1 when the group of plates of the fully charged lead-acid battery is pulled out of the battery case is 1.8 times or more the weight W2 of the group of plates, the positive electrode plate comprises a positive electrode current collector and a positive electrode material, and at least the electrolyte and the positive electrode material contain phosphorus, and The present invention relates to a lead-acid battery (particularly a liquid-type (vented) lead-acid battery) in which the sum of the amount of phosphorus (mmol) contained in the electrolyte and the amount of phosphorus (mmol) contained in the positive electrode material, divided by the volume (L) of the electrolyte, is 8 mmol / L to 100 mmol / L, the phosphorus contained in the electrolyte exists as anions derived from phosphoric acid, the electrolyte contains a metal cation, the metal cation contains sodium (Na) ions, and the concentration of sodium ions in the electrolyte is 30 mmol / L or more.

[0020] The lead-acid battery described in (1) above contains a predetermined amount of phosphorus in the electrolyte and positive electrode material, and the electrolyte contains Na ions at a concentration of 30 mmol / L or higher. When phosphorus and Na ions are used in combination, the pull-out load of the electrode group gradually increases in a charge-discharge cycle test simulating PSOC (i.e., PSOC cycle test), and further increases from the initial value of 1.8 times its own weight or more. As a result, stratification is significantly suppressed. Therefore, PSOC cycle life performance and low-temperature HR discharge performance are improved. Note that as stratification progresses, in the upper part of the electrode group, the decrease in electrolyte density prevents discharge to the inside of the electrode pores, reducing the discharge capacity, and in the lower part of the electrode group, the increase in density reduces the amount of lead sulfate generated inside the electrode pores, making it easier for the surface of the active material particles to be coated with lead sulfate, reducing the discharge capacity. Suppression of stratification is important in suppressing the decrease in low-temperature HR discharge performance.

[0021] Here, the extraction load (initial value) W1 when withdrawing the electrode plate group of a fully charged lead-acid battery from the battery case refers to the extraction load when withdrawing the electrode plate group of a fully charged lead-acid battery from the battery case immediately after chemical formation, when 720 hours or less have elapsed since chemical formation without being used, or at the beginning of use.

[0022] The extraction force required to remove the electrode plates from a fully charged lead-acid battery is measured using the following procedure. First, the top cover of the fully charged lead-acid battery is cut off to drain all the electrolyte. Immediately afterward, with the electrolyte still soaked into the electrode plates, a hook is attached to a part of the electrode plate group (for example, the strap portion) and the electrode plate group is pulled out of the battery case. At this time, a digital force gauge is used to measure the force required to pull the electrode plate group out of the battery case. The measured force is taken as the extraction force of the electrode plate group. The weight of the electrode plate group (W2) is also measured. Then, the ratio of the extraction force W1 to the weight of the electrode plate group W2 (W1 / W2) is calculated.

[0023] The top cover is cut horizontally so that the straps connected to the electrode plates remain. Then, the pull-out load and weight of the electrode plates of all cells except those with some positive and negative poles remaining (usually the cells at both ends) are measured sequentially. The pulled-out electrode plates are returned to the battery case, and the pull-out load and weight of the electrode plates of the next cell are measured. For a 6-cell battery, the W1 / W2 ratio is measured for four cells, and the average value is calculated.

[0024] The W1 / W2 ratio can be controlled, for example, by sequentially changing the width of the battery case (cell chamber) and the thickness of the electrode plate group. The width of the battery case (cell chamber) refers to the dimensions of the space within the battery case (the space where the electrode plate group is arranged) in the direction in which the positive and negative electrode plates are stacked. The thickness of the electrode plate group may be changed by the amount of positive electrode material held in the positive electrode plate, the amount of negative electrode material held in the negative electrode plate, the shape of the positive electrode current collector, the shape of the negative electrode current collector, etc. Note that the pull-out load is usually about the same before and after chemical formation, or does not differ significantly.

[0025] In this specification, a lead-acid battery in its initial state of use refers to a battery that has not been in use for very long and has not deteriorated much (for example, a battery that has been in use for less than 720 hours, including the time since chemical treatment).

[0026] Furthermore, simply setting the initial extraction load (value) when pulling out the electrode plates of a fully charged lead-acid battery from the battery case to 1.8 times or more the weight of the electrode plates is insufficient to suppress stratification, even though sufficient compressive force is applied to the electrode plates. Even if the initial extraction load (value) were 2.8 times or more the weight of the electrode plates, it would still be difficult to suppress stratification. It is important to gradually increase the compressive force (extraction load) applied to the electrode plates through the action of phosphorus and sodium ions. When the extraction load is gradually increased in this way, a uniform compressive force is applied to the entire electrode plate group, rather than a localized compressive force. This is thought to significantly reduce the space in the electrolyte where sulfate ions can settle, and thus significantly suppress stratification.

[0027] However, if the extraction load (initial value) when pulling the electrode plates of a fully charged lead-acid battery out of the battery case is less than 1.8 times the weight of the electrode plates themselves, it is difficult to suppress stratification. This is because even if the compressive force applied to the electrode plates increases due to the action of phosphorus and sodium ions, it does not reach a compressive force sufficient to suppress stratification.

[0028] In the lead-acid battery described in (1) above, the phosphorus contained in the electrolyte may exist as anions derived from phosphoric acid. Anions derived from phosphoric acid are readily soluble in the electrolyte and are chemically stable. Anions derived from phosphoric acid may be monovalent to trivalent anions. Anions derived from phosphoric acid may be derived from phosphoric acid (H3PO4) or from phosphates (such as Na3PO4). Phosphates may also be hydrogen phosphates. Hydrogen phosphates may be monohydrogen salts (such as Na2HPO4) or dihydrogen salts (such as NaH2PO4).

[0029] (2) In the lead-acid battery described in (1) above, the negative electrode plate comprises a negative electrode current collector and a negative electrode material, and the negative electrode material may contain an organic shrinkage inhibitor having a sulfur element content of 3000 μmol / g to 7000 μmol / g.

[0030] In the lead-acid battery described in (2) above, the PSOC cycle life performance and low-temperature HR performance are further improved. When an organic shrinkage inhibitor with a high sulfur content is used, the particle size of the generated lead sulfate is made finer, and the compressive force applied to the electrode group (especially the negative electrode) is thought to become more uniform. As a result, the space in which sulfate ions settle is thought to be reduced even more significantly.

[0031] (3) In the lead-acid battery described in (1) or (2) above, the positive electrode current collector may contain tin (Sn), and the tin content in the positive electrode current collector may be 1.0% by mass to 2.4% by mass.

[0032] In the lead-acid battery described in (3) above, corrosion of the positive electrode current collector is suppressed, and high-temperature cycle characteristics are improved. The Sn contained in the positive electrode current collector precipitates at the grain boundaries of the lead alloy. It is thought that the Sn precipitates at the grain boundaries suppress the progression of corrosion of the lead alloy. Furthermore, by suppressing the corrosion of the positive electrode current collector, the compressive force applied to the electrode group (especially the positive electrode) becomes more uniform even in high-temperature cycle tests, and the effect of suppressing stratification becomes more pronounced.

[0033] (4) A lead-acid battery described in any one of (1) to (3) above is useful as a power source for applications where charging and discharging are controlled in an undercharged state called a partially charged state (PSOC). Specific examples of power sources for applications where charging and discharging are controlled by PSOC include power sources for ISS-controlled vehicles (ISS-controlled vehicles) and auxiliary equipment. In other words, the effect of suppressing stratification by the configuration of the present invention is more likely to become apparent in lead-acid batteries where charging and discharging are controlled by PSOC.

[0034] In this specification, the fully charged state of a liquid lead-acid battery is defined according to the definition in JIS D5301:2019. More specifically, in a water bath at 25°C ± 2°C, the 20-hour rate current I is charged until the terminal voltage (in volts) or the electrolyte density converted to 20°C shows a constant value with three significant figures for three consecutive 15-minute intervals. 20 Twice the current 2 × I 20 (Unit: A) The fully charged state of a lead-acid battery is defined as the state in which it has been charged. Note that n-hour rate current I n This refers to a current (A) that is 1 / n of the Ah value listed for the n-hour rate rated capacity. The value listed for the rated capacity is a value in Ah (ampere-hour). The unit of the current set based on the value listed for the rated capacity is A (ampere).

[0035] A fully charged lead-acid battery is a lead-acid battery that has been charged to its full capacity after chemical formation. The timing for charging a lead-acid battery to its full capacity can be immediately after chemical formation, or after a certain amount of time has passed since formation (e.g., 720 hours or less). For example, a lead-acid battery that has been chemically formed and is in use (preferably in the early stages of use) may be charged.

[0036] The lead-acid battery according to an embodiment of the present invention will be described in more detail below with reference to the drawings. However, the present invention is not limited to the following embodiments.

[0037] The following describes examples of components of a lead-acid battery.

[0038] (Positive plate) The positive electrode plate comprises a positive electrode current collector and a positive electrode material. The positive electrode material is held by the positive electrode current collector. The positive electrode material is the portion of the positive electrode plate excluding the positive electrode current collector. Adhesive members such as conductive layers, mats, and pasting paper may be attached to the positive electrode plate. Since the adhesive members are used integrally with the positive electrode plate, they are included as components of the positive electrode plate. When the positive electrode plate includes adhesive members, the positive electrode material is the portion of the positive electrode plate excluding the positive electrode current collector and the adhesive members.

[0039] The positive electrode current collector may be formed by casting lead (Pb) or a lead alloy, or by processing a sheet of lead or a lead alloy. Processing methods may include, for example, expansion or punching. Using a grid-like current collector as the positive electrode current collector makes it easier to support the positive electrode material.

[0040] As the lead alloy used for the positive electrode current collector, Pb-Ca alloys and Pb-Ca-Sn alloys, which have excellent corrosion resistance and mechanical strength, are preferred. The positive electrode current collector may have metal layers of different compositions, and the metal layers may be one layer or multiple layers.

[0041] From the viewpoint of suppressing corrosion of the positive electrode current collector and improving high-temperature cycle characteristics, it is preferable that the positive electrode current collector contains at least Sn. The Sn content in the positive electrode current collector may be, for example, 1.0 mass% to 2.4 mass%, 1.3 mass% to 2.4 mass%, or 1.6 mass% to 2.4 mass%. Even with a small Sn content, a certain degree of improvement in corrosion resistance can be obtained, but the improvement in corrosion resistance becomes significant at 1.0 mass% or higher, and becomes even more significant at 1.3 mass% to 2.4 mass%, or 1.6 mass% to 2.4 mass%. When the Sn content exceeds 2.4 mass%, the improvement in high-temperature cycle characteristics tends to gradually decrease. Also, since Sn is expensive, from the viewpoint of suppressing cost increases, it is preferable that the Sn content in the positive electrode current collector be 2.4 mass% or less.

[0042] The quantitative determination of Sn contained in the positive electrode current collector can be performed, for example, according to the lead-separated inductively coupled plasma atomic emission spectroscopy method described in JIS H2105. When analyzing the elemental content of the positive electrode current collector of a positive electrode plate removed from a lead-acid battery, first, the positive electrode plate is vibrated to detach the positive electrode material from the positive electrode current collector. Then, a ceramic knife is used to remove the remaining positive electrode material around the positive electrode current collector, and a portion of the positive electrode current collector with metallic luster is taken as a sample. The collected sample is decomposed with tartaric acid and dilute nitric acid to obtain an aqueous solution. Hydrochloric acid is added to the aqueous solution to precipitate lead chloride, which is then filtered, and the filtrate is collected. Subsequently, the emission intensity of Sn in the solution is measured by ICP-AES (Inductively Coupled Plasma Atomic Emission Spectroscopy) using an ICP atomic emission spectrometer (e.g., Shimadzu Corporation ICPS-8000). Then, the mass of Sn contained in the solution is determined using a pre-prepared calibration curve. The ratio of the obtained Sn mass to the mass of the positive electrode current collector sample subjected to analysis is determined as the Sn content.

[0043] The positive electrode material contains a positive electrode active material that exhibits capacity through a redox reaction. The positive electrode active material includes lead dioxide, lead sulfate, etc. The positive electrode material further contains phosphorus (P).

[0044] Phosphorus may be incorporated into the positive electrode material by adding phosphorus compounds such as phosphoric acid and phosphates to the positive electrode paste used when manufacturing the unformed positive electrode plate. Alternatively, phosphorus may be introduced into the positive electrode material by dissolving at least one selected from the group consisting of phosphoric acid and phosphates in an electrolyte and allowing the electrolyte to react with the positive electrode material. In this case, anions derived from phosphoric acid are also present in the electrolyte. However, up to approximately 90% is adsorbed onto the positive electrode material.

[0045] The amount of phosphorus contained in the positive electrode material is controlled so that the value obtained by dividing the sum of the amount of phosphorus contained in the electrolyte (mmol) and the amount of phosphorus contained in the positive electrode material (mmol) by the volume of the electrolyte (L) (hereinafter also referred to as "P content (EP)") is between 8 mmol / L and 100 mmol / L. The P content (EP) may be controlled to be 25 mmol / L or more, or 50 mmol / L or less. The P content (EP) may be controlled to be between 25 mmol / L and 100 mmol / L, or between 25 mmol / L and 50 mmol / L.

[0046] The phosphorus content in the positive electrode material can be determined by taking a sample of the positive electrode material from the positive electrode plate removed from a fully charged lead-acid battery and measuring it using ICP-AES. The sample of the positive electrode material is taken from the positive electrode plate removed from a fully charged lead-acid battery.

[0047] Specifically, a suitable amount of dry positive electrode material is taken as a sample, and its mass is measured. The positive electrode material sample is recovered from the positive electrode plate using the following procedure: First, a fully charged lead-acid battery is disassembled, and the obtained positive electrode plate is washed with water for 3 to 4 hours to remove the electrolyte from the positive electrode plate. The washed positive electrode plate is dried in a constant temperature bath at 60°C ± 5°C for 5 hours or more. After drying, if the positive electrode plate contains adhesive material, the adhesive material is removed from the positive electrode plate by peeling it off. A sample of positive electrode material for analysis is obtained by taking a sample of the positive electrode material from near the center of the top, bottom, left, and right sides when viewed from the front of the positive electrode plate.

[0048] Next, the entire sample is dissolved in a mixed aqueous solution containing tartaric acid, nitric acid, and hydrogen peroxide. The solution obtained by total dissolution is diluted to a fixed volume with deionized water as needed, and then the emission intensity of phosphorus in the solution is measured by ICP-AES using an ICP emission spectrometer (ICPS-8000, Shimadzu Corporation). The mass of phosphorus contained in the solution is then determined using a pre-prepared calibration curve. The ratio of the obtained mass of phosphorus to the mass of the sample of positive electrode material used for analysis is determined as the phosphorus content.

[0049] The amount of phosphorus (mmol) contained in the positive electrode material can be calculated from the sample mass, the measured value, and the total mass of the positive electrode material.

[0050] Positive electrodes are obtained by chemically converting unconverted positive electrodes. Unconverted positive electrodes are obtained by filling a positive electrode current collector with positive electrode paste, allowing it to mature, and drying. Positive electrode paste is prepared, for example, by kneading a mixture containing lead powder, water, and sulfuric acid (and optionally phosphorus (or a phosphorus compound)). Such positive electrodes are also called paste-type positive electrodes.

[0051] Chemical treatment may be carried out by immersing the electrode plate group, including the untreated positive electrode plate, in the sulfuric acid-containing electrolyte in the lead-acid battery case and charging the electrode plate group. Chemical treatment may also be carried out before the assembly of the lead-acid battery or the electrode plate group.

[0052] (Negative electrode plate) The negative electrode plate comprises a negative electrode current collector and a negative electrode material. The negative electrode material is held by the negative electrode current collector. The negative electrode material is the portion of the negative electrode plate excluding the negative electrode current collector. Note that adhesive members such as conductive layers, mats, and pasting paper may be attached to the negative electrode plate. The adhesive members are included as components of the negative electrode plate. When the negative electrode plate includes adhesive members, the negative electrode material is the portion of the negative electrode plate excluding the negative electrode current collector and the adhesive members.

[0053] The negative electrode current collector may be formed by casting lead (Pb) or a lead alloy, or by processing a lead or lead alloy sheet. The processing method may be expansion or punching. Using a grid-like current collector as the negative electrode current collector makes it easier to support the negative electrode material.

[0054] The lead alloy used for the negative electrode current collector may be any of the following: a Pb-Sb alloy, a Pb-Ca alloy, or a Pb-Ca-Sn alloy. The lead alloy used for the negative electrode current collector may also contain at least one additive element selected from the group consisting of Ba, Ag, Al, Bi, As, Se, Cu, etc. The negative electrode current collector may have metal layers of different compositions, and the metal layers may be one layer or multiple layers.

[0055] The negative electrode material contains a negative electrode active material that exhibits capacity through an oxidation-reduction reaction. The negative electrode active material includes lead, lead sulfate, etc. The negative electrode material may contain other additives as needed. The additives may include organic shrinkage inhibitors, carbonaceous materials, barium sulfate, etc.

[0056] Examples of organic shrinkage inhibitors include lignin, lignin sulfonic acid, and synthetic organic shrinkage inhibitors. Organic shrinkage inhibitors may be used individually or in combination of two or more. The content of the organic shrinkage inhibitor in the negative electrode material is, for example, 0.01% by mass or more and 1% by mass or less.

[0057] Among organic shrinkage inhibitors, those with a sulfur content of 3000 μmol / g to 7000 μmol / g are preferred. Such organic shrinkage inhibitors may be synthetic organic shrinkage inhibitors. Such organic shrinkage inhibitors may be, for example, formaldehyde condensates of aromatic compounds (such as phenolic compounds). By using an organic shrinkage inhibitor with a sulfur content of 3000 μmol / g to 7000 μmol / g, the particle size of the resulting lead sulfate is refined, the compressive force applied to the electrode group is further improved, and the effect of suppressing stratification becomes even more pronounced. In addition, using more than a certain amount of phosphorus may reduce low-temperature HR performance, but by using an organic shrinkage inhibitor with a sulfur content of 3000 μmol / g to 7000 μmol / g, it becomes easier to ensure high low-temperature HR performance.

[0058] The sulfur element is included in organic shrinkage inhibitors as a sulfur-containing group. Among sulfur-containing groups, the stable forms, sulfonic acid groups or sulfonyl groups, are preferred, with sulfonic acid groups being particularly preferred. Sulfonic acid groups may exist in acid form or in salt form, such as a sodium salt. Sulfur-containing groups may be directly bonded to the aromatic ring of an aromatic compound, or they may be bonded to the aromatic ring as an alkyl chain having a sulfur-containing group, for example.

[0059] The organic shrinkage inhibitor may contain one unit of aromatic compound, or two or more units of aromatic compounds. Note that the term "aromatic compound unit" refers to a unit derived from an aromatic compound incorporated into the condensate.

[0060] Aromatic rings in aromatic compounds include benzene rings and naphthalene rings. When an aromatic compound has multiple aromatic rings, these rings may be directly bonded or linked by linking groups (e.g., alkylene groups (including alkylidene groups), sulfone groups). Examples of such structures include bisarene structures (biphenyl, bisphenylalkane, bisphenylsulfone, etc.). Examples of aromatic compounds include compounds having the above-mentioned aromatic rings and at least one selected from the group consisting of a hydroxyl group and an amino group. The hydroxyl group or amino group may be directly bonded to the aromatic ring, or it may be bonded as an alkyl chain having a hydroxyl group or an amino group.

[0061] Note that the hydroxyl group also includes the salt of the hydroxyl group (-OMe). The amino group also includes the salt of the amino group (specifically, the salt with anion). Examples of Me include alkali metals (Li, K, Na, etc.) and Group 2 metals of the periodic table (Ca, Mg, etc.).

[0062] Preferred aromatic compounds include bisphenol compounds, hydroxybiphenyl compounds, bisarene compounds having an amino group (bisarylalkane compounds having an amino group, bisarylsulfone compounds having an amino group, biphenyl compounds having an amino group, etc.), hydroxyarene compounds (hydroxynaphthalene compounds, phenol compounds, etc.), and aminoarene compounds (aminonaphthalene compounds, aniline compounds (aminobenzenesulfonic acid, alkylaminobenzenesulfonic acid, etc.)). The aromatic compounds may further have substituents. The organic shrinkage inhibitor may contain one or more residues of these compounds. Preferred bisphenol compounds include bisphenol A, bisphenol S, and bisphenol F.

[0063] The weight-average molecular weight (Mw) of the organic shrinkage inhibitor may be 7,000 or more. For example, the Mw of the organic shrinkage inhibitor may be 100,000 or less, or 20,000 or less.

[0064] In this specification, the Mw of the organic shrinkage inhibitor is a value measured using sodium polystyrene sulfonate as the standard substance. The Mw of the organic shrinkage inhibitor is measured using gel permeation chromatography (GPC).

[0065] As carbonaceous materials, carbon black, artificial graphite, natural graphite, hard carbon, soft carbon, etc., can be used. One type of carbonaceous material may be used alone, or two or more types may be used in combination. The carbonaceous material content in the negative electrode material is, for example, 0.1% by mass or more and 3% by mass or less.

[0066] The barium sulfate content in the negative electrode material is, for example, 0.1% by mass or more and 3% by mass or less.

[0067] The negative electrode plate is obtained by chemically converting an unconverted negative electrode plate. The unconverted negative electrode plate is obtained by filling a negative electrode current collector with negative electrode paste, allowing it to mature, and drying. The negative electrode paste is prepared by kneading a mixture containing lead powder, water, and sulfuric acid. The negative electrode paste may optionally contain organic shrinkage inhibitors, carbonaceous materials, barium sulfate, etc.

[0068] The chemical treatment may be carried out by immersing the electrode plate group, including the untreated negative electrode plate, in an electrolyte containing sulfuric acid in the lead-acid battery case, thereby charging the electrode plate group. The chemical treatment may also be carried out before the assembly of the lead-acid battery or the electrode plate group. The charged negative electrode active material contains spongy lead.

[0069] (a) Qualitative analysis of organic shrinkage inhibitors First, 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. Washing is continued until a pH test paper is pressed against the surface of the washed negative electrode plate and the color of the test paper does not change. However, the washing time should be no more than 2 hours. The washed negative electrode plate is dried under reduced pressure at 60°C ± 5°C for about 6 hours. If the negative electrode plate contains adhesive material after drying, the adhesive material is removed by peeling. The mass of the dried material (negative electrode plate) is measured. Next, sample A is obtained by scraping and separating the negative electrode material from the negative electrode current collector. Sample A is pulverized as needed and used for analysis of the constituent components of the negative electrode material.

[0070] A predetermined amount of the pulverized sample A is taken and weighed, then immersed in a 1 mol / L NaOH aqueous solution to extract the organic shrinkage inhibitor. Next, insoluble components are removed from the extract by filtration, and the resulting solution B is desalted, concentrated, and dried. Desalting is performed using a desalting column, by passing solution B through an ion exchange membrane, or by placing solution B in a dialysis tube and immersing it in distilled water. Drying this yields sample C, which is a powder of the organic shrinkage inhibitor.

[0071] The organic shrinkage inhibitor is identified by combining information obtained from methods such as the infrared spectroscopic spectrum of sample C, the ultraviolet-visible absorption spectrum of a solution obtained by dissolving sample C in distilled water or the like, the nuclear magnetic resonance (NMR) spectrum of a solution obtained by dissolving sample C in a solvent such as heavy water, or gas chromatography-mass spectrometry (GC-MS), which can provide information on the individual compounds constituting the substance.

[0072] (b) Quantitative analysis of organic shrinkage inhibitors The ultraviolet-visible absorption spectrum of solution B, obtained in the same manner as in (a) above, is measured. The content of the organic shrinkage inhibitor is determined using the intensity of the peak characteristic of the organic shrinkage inhibitor and a previously prepared calibration curve.

[0073] Furthermore, when obtaining lead-acid batteries with an unknown organic shrinkage inhibitor content and measuring the content, it may not be possible to use the same organic shrinkage inhibitor in the calibration curve because the structural formula of the organic shrinkage inhibitor cannot be precisely identified. In this case, a calibration curve is created using the organic shrinkage inhibitor extracted from the negative electrode of the battery and a separately available organic polymer that exhibits a similar shape in its ultraviolet-visible absorption spectrum, infrared spectroscopic spectrum, and NMR spectrum.

[0074] (c) Sulfur element content in organic shrinkage inhibitors Similarly to (a) above, after obtaining a powder sample C of the organic shrinkage inhibitor, the sulfur elements in 0.1 g of the organic shrinkage inhibitor are converted to sulfuric acid by the oxygen combustion flask method. At this time, by burning the powder sample in a flask containing the adsorbent, an eluate is obtained in which sulfate ions are dissolved in the adsorbent. Next, the sulfur element content (C1) in 0.1 g of the organic shrinkage inhibitor is determined by titrating the eluate with barium perchlorate using thorin as an indicator. Next, C1 is multiplied by 10 to calculate the sulfur element content (μmol / g) in the organic shrinkage inhibitor per gram.

[0075] (Separator) Lead-acid batteries typically have a separator between the negative and positive electrodes. A microporous membrane can be used as the separator.

[0076] A microporous membrane is a porous sheet mainly composed of materials other than fibrous components. Preferably, the amount of materials other than fibrous components is, for example, 60% by mass or more. A microporous membrane can be obtained, for example, by extruding a resin composition containing a pore-forming agent into a sheet, and then removing the pore-forming agent to form pores. A microporous membrane is preferably composed of an acid-resistant polymer component. Polyolefins are preferred as the polymer component.

[0077] The thickness of the separator placed between the negative electrode plate and the positive electrode plate should be selected according to the distance between the two plates.

[0078] (electrolyte) The electrolyte is an aqueous solution containing sulfuric acid. Preferably, the electrolyte contains phosphorus as an anion derived from phosphoric acid.

[0079] The phosphorus content (EP) is the sum of the amount of phosphorus (mmol) contained in the positive electrode material and the amount of phosphorus (mmol) contained in the electrolyte, which can be determined by the method described above, divided by the volume of the electrolyte (L) (P content (EP) = (Amount of phosphorus contained in positive electrode material (mmol)) + Amount of phosphorus in the electrolyte (mmol)) / Volume of electrolyte (L)).

[0080] Qualitative and quantitative analysis of phosphorus in electrolytes can be performed by liquid chromatography-mass spectrometry (LC-MS).

[0081] The electrolyte further contains metal cations, the metal cations containing at least sodium (Na) ions. The metal cations may also contain metal cations other than Na ions, such as Li and Al.

[0082] The concentration of sodium ions in the electrolyte is 30 mmol / L or more, and may be 30 mmol / L to 150 mmol / L, or may be 30 mmol / L to 105 mmol / L.

[0083] The concentration of metal cations in the electrolyte is determined by analyzing the electrolyte taken out from a fully charged lead storage battery by ICP-AES. More specifically, using an ICP emission spectroscopic measuring device, the types of metal cations in the electrolyte are identified, and the emission intensity of the metal cations is measured. From the measured value of this emission photometry and the calibration curve prepared in advance, the concentration of the metal cations contained in the electrolyte is determined. As the ICP emission spectroscopic measuring device, ICPS-8000 manufactured by Shimadzu Corporation is used.

[0084] The density at 20°C of the electrolyte in a fully charged lead storage battery is, for example, 1.20 g / cm 3 or more, and may be 1.25 g / cm 3 or more. The density at 20°C of the electrolyte is 1.35 g / cm 3 or less, and preferably 1.32 g / cm 3 or less. The density at 20°C of the electrolyte in a fully charged lead storage battery is, for example, 1.20 g / cm 3 ~1.35 g / cm 3 and may be 1.25 g / cm 3 ~1.32 g / cm 3 or the like.

[0085] The mass of the electrolyte can be calculated from the mass of the cell containing the electrolyte and the mass of the cell from which the electrolyte has been removed by washing and drying. The volume (L) of the electrolyte can be calculated from the mass of the electrolyte and the density of the electrolyte.

[0086] (Example of lead storage battery) Figure 1 shows the external appearance and part of the internal structure of a lead-acid battery according to one embodiment. The lead-acid battery 1 comprises a battery case 12 that houses an electrode plate group 11 and an electrolyte (not shown). The inside of the battery case 12 is divided into a number of cell chambers 14 by a partition wall 13. Each cell chamber 14 houses one electrode plate group 11. The opening of the battery case 12 is closed with a lid 15 equipped with 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 replenishing water, the vent plug 18 is removed and the water is replenished. The vent plug 18 may also have a function of discharging gas generated in the cell chamber 14 to the outside of the battery.

[0087] Each electrode plate group 11 is constructed by stacking multiple negative electrode plates 2 and positive electrode plates 3 via separators 4. Here, a bag-shaped separator 4 that houses the negative electrode plates 2 is shown, but the shape of the separator is not particularly limited. In the cell chamber 14 located at one end of the battery case 12, a negative electrode strap 6 connecting multiple negative electrode plates 2 in parallel is connected to a through connector 8, and a positive electrode strap 5 connecting 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 on the outside of the lid 15. In the cell chamber 14 located at the other end of the battery case 12, a negative electrode column 9 is connected to the negative electrode strap 6, and a through connector 8 is connected to the positive electrode strap 5. The negative electrode column 9 is connected to a negative electrode terminal 16 on the outside of the lid 15. Each through connector 8 passes through a through hole provided in the partition wall 13, connecting the electrode plate groups 11 of adjacent cell chambers 14 in series.

[0088] Note that Figure 1 is merely one example of a liquid-type lead-acid battery, and the structure of the lead-acid battery relating to this disclosure is not limited to the example shown.

[0089] The following describes the evaluation method for lead-acid batteries. For the evaluation, a lead-acid battery (nominal voltage 12V) with six cells (connected in series), each containing six positive electrodes and six negative electrodes, will be used. The rated 20-hour rate capacity of the lead-acid battery is 60Ah, and the rated 5-hour rate capacity is 48Ah. However, the evaluation battery is not limited to a 12V battery; a battery other than 12V (6 cells) may also be used. In that case, the test voltage may be the product of 12 / 6 = 2(V) and the number of cells under the following conditions.

[0090] (PSOC cycle durability) In a water bath at 25°C ± 3°C, the following steps 1 to 4 are repeated, and the number of cycles until the terminal voltage reaches 10V is used as an indicator of PSOC cycle endurance. In Table A, CC discharge means constant current discharge, and CC-CV charge means constant current constant voltage charge. In Table A, 7 × I 20 CC-CV charging of (A) / 2.4(V) is 7×I 20 (A) means charging to 2.4V / cell (14.4V for 6 cells) with a constant current, and charging at a constant voltage of 2.4V / cell. The total CC-CV charging time is 40 minutes. In this specification, 1CA is a current value (A) equal to the rated capacity (Ah) of the battery. For example, if the rated capacity of the battery is 30A, then 1CA is 30A and 1mCA is 30mA. Note that "adjustment discharge" is a discharge to adjust the DOD (Depth of Discharge) before repeating cycles 2 and 3. 20 " indicates the 20-hour rate current, where 1CA = 20 × I 20 That is the case.

[0091] [Table A]

[0092] (Low temperature HR discharge performance) For a fully charged lead-acid battery with a nominal voltage of 12V, discharge at a discharge current of 25 × I5(A) at -15±1℃ until the terminal voltage reaches 6V (1.0V / cell), and the discharge time is determined. A longer discharge duration indicates better low-temperature HR discharge performance. The timing of the low-temperature HR discharge performance measurement is after repeating the PSOC cycle (one cycle consists of the process of performing steps 2 and 3) shown in Table A for 340 cycles. Step 2 is stopped midway through the 341st cycle, and the battery is charged to a fully charged state for the measurement.

[0093] (High-temperature cycle test) A "high-temperature stability test" will be conducted in accordance with SAE J2801. Specifically, a low-temperature HR discharge test will be performed after 1220 cycles of a 75°C 1'-10' light load test, and the discharge time will be determined. A longer discharge duration indicates higher stability at high temperatures, which is advantageous for improving the PSOC cycle life.

[0094] [Examples] The present invention will be described in detail below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0095] 《Lead acid battery R1~R16》 (1) Fabrication of the negative electrode plate A negative electrode paste is prepared by mixing lead oxide, carbon black, barium sulfate, ligninsulfonic acid (sulfur content 600 μmol / g), water, and sulfuric acid. The negative electrode paste is filled into the mesh of an expanded grid made of a Pb-Ca-Sn alloy, which is the negative electrode current collector, and then aged and dried to obtain an unformed negative electrode plate. The amounts of carbon black, barium sulfate, and lignin are adjusted so that they are 0.3 mass%, 2.1 mass%, and 0.1 mass%, respectively, when measured in the fully charged, already formed state.

[0096] (2) Fabrication of the positive electrode plate A positive electrode paste is prepared by mixing lead oxide, water, and sulfuric acid. The positive electrode paste is filled into the mesh of an expanded grid made of a Pb-Ca-Sn alloy (Sn content 0.8 mass%), which serves as the positive electrode current collector, and then aged and dried to obtain an unformed positive electrode plate.

[0097] (3) Separator Prepare a bag-shaped separator by folding a polyethylene microporous membrane in half.

[0098] (4) Preparation of electrolyte The electrolyte is prepared by dissolving phosphoric acid (H3PO4) and sodium sulfate in an aqueous sulfuric acid solution so that the sum of the amount of phosphorus (mmol) in the electrolyte and the amount of phosphorus (mmol) in the positive electrode material, divided by the volume of the electrolyte (L) (P content (EP)), and the sodium (Na) ion concentration in the electrolyte are as shown in Table 1. The density of the electrolyte after chemical conversion is 1.26 ± 0.01 g / cm³. 3 ~1.30±0.01 g / cm³ 3 This will be within the range of [the specified range].

[0099] (5) Manufacturing of lead-acid batteries An unformed positive electrode plate is housed in a bag-shaped first separator, and six unformed negative electrode plates and six unformed positive electrode plates are stacked alternately to form an electrode plate group.

[0100] The tabs of the positive electrode plate and the tabs of the negative electrode plate are welded to the positive and negative electrode straps, respectively, using the cast-on-strap (COS) method. The electrode plates are inserted into a polypropylene battery case so that the W1 / W2 ratio is as shown in Table 1, and the electrolyte is poured in. A chemical conversion is then performed inside the battery case to assemble a liquid lead-acid battery.

[0101] The W1 / W2 ratio (pull-out load) was changed, for example, by sequentially changing the width of the battery case (cell chamber), the thickness of the electrode plate group, etc., or by placing spacers as needed between the inner wall of the battery case and the electrode plates at the ends of the electrode plate group.

[0102] (6) Evaluation The fabricated lead-acid battery was fully charged using the procedure described above, and its PSOC cycle endurance and low-temperature HR discharge characteristics were evaluated using the method described above. The results are shown in Table 1. Each evaluation is expressed as a relative value (%) with the result of lead-acid battery R1 set to 100%. A higher relative value indicates better performance.

[0103] [Table 1]

[0104] Table 1 shows that simply applying phosphorus to lead-acid batteries does not improve PSOC cycle life or low-temperature HR discharge performance because it promotes stratification of the electrolyte (R1-R7). Furthermore, PSOC cycle durability decreases significantly when the phosphorus content (EP) is 150 mmol / L or higher. This is thought to be due to a significant decrease in charge acceptance.

[0105] Furthermore, simply adding sodium ions to the electrolyte only provides limited improvement in PSOC cycle durability and low-temperature HR discharge performance, even when the extraction load is increased (R8~R16).

[0106] 《Lead acid battery R17~R31》 The electrolyte was prepared by dissolving phosphoric acid (H3PO4) and sodium sulfate in an aqueous sulfuric acid solution so that the sum of the amount of phosphorus (mmol) in the electrolyte and the amount of phosphorus (mmol) in the positive electrode material, divided by the volume of the electrolyte (L) (P content (EP)), and the sodium (Na) ion concentration in the electrolyte were as shown in Table 2. The electrode plates were then inserted into a polypropylene battery case so that the W1 / W2 ratio was as shown in Table 1. Otherwise, the lead-acid battery was assembled and evaluated in the same manner as described above. The results are shown in Table 2.

[0107] [Table 2]

[0108] Table 2 shows that simply applying phosphorus to lead-acid batteries, even with high pull-out loads, only provides limited improvements in PSOC cycle life and low-temperature HR performance.

[0109] While increasing the W1 / W2 ratio to 9 or higher is expected to improve PSOC cycle life and low-temperature HR performance, it raises concerns about manufacturing defects.

[0110] 《Lead acid battery R32~R51》 The electrolyte was prepared by dissolving phosphoric acid (H3PO4) and sodium sulfate in an aqueous sulfuric acid solution so that the sum of the amount of phosphorus (mmol) in the electrolyte and the amount of phosphorus (mmol) in the positive electrode material, divided by the volume of the electrolyte (L) (P content (EP)), and the sodium (Na) ion concentration in the electrolyte were as shown in Table 2. The electrode plates were then inserted into a polypropylene battery case so that the W1 / W2 ratio was as shown in Table 1. Otherwise, the lead-acid battery was assembled and evaluated in the same manner as described above. The results are shown in Table 3.

[0111] [Table 3]

[0112] In the presence of phosphorus and sodium ions, the compressive force on the electrode group increases during the PSOC cycle test. However, when the pull-out load is low (W1 / W2=1), the increase in compressive force does not keep pace, resulting in limited improvement in PSOC cycle life and no improvement in low-temperature HR performance.

[0113] Even in the presence of both phosphorus and sodium ions, if the sodium ion content is low (R38-R43), increasing the phosphorus content does not result in a synergistic effect between phosphorus and sodium ions, and the compressive force on the electrode group does not increase sufficiently during the PSOC cycle test. Therefore, the improvement in PSOC cycle life and low-temperature HR performance is limited. Furthermore, if the quantitative balance between phosphorus and sodium ions is poor (R44-R51), the PSOC cycle life may decrease, and the improvement in low-temperature HR performance is also limited.

[0114] 《Lead acid batteries E1~E17》 The electrolyte was prepared by dissolving phosphoric acid (H3PO4) and sodium sulfate in an aqueous sulfuric acid solution so that the sum of the amount of phosphorus (mmol) in the electrolyte and the amount of phosphorus (mmol) in the positive electrode material, divided by the volume of the electrolyte (L) (P content (EP)), and the sodium (Na) ion concentration in the electrolyte were as shown in Table 2. The electrode plates were then inserted into a polypropylene battery case so that the W1 / W2 ratio was as shown in Table 1. Otherwise, the lead-acid battery was assembled and evaluated in the same manner as described above. The results are shown in Table 4.

[0115] [Table 4]

[0116] Table 4 shows that when the phosphorus content (EP) is between 8 and 100 mmol / L and 30 mmol / L or higher, and the W1 / W2 ratio is 1.8 or higher, the PSOC cycle life and low-temperature HR performance are improved. This is because the compressive force on the electrode group increases during the PSOC cycle test, suppressing stratification.

[0117] 《Lead acid battery E19~E21》 Except for using a synthetic organic shrinkage inhibitor (formaldehyde condensate of a phenol compound) with a sulfur (S) content as shown in Table 5, instead of ligninsulfonic acid (sulfur element content 600 μmol / g) as the negative electrode material, the lead-acid battery was assembled and evaluated in the same manner as lead-acid battery E8. The results are shown in Table 5.

[0118] [Table 5]

[0119] Table 5 shows that using a synthetic organic shrinkage inhibitor with a high sulfur content improves the PSOC cycle life and low-temperature HR performance of lead-acid batteries compared to using ligninsulfonic acid, a conventional organic shrinkage inhibitor.

[0120] 《Lead acid battery E22~E26》 The lead-acid battery was assembled and evaluated in the same manner as lead-acid battery E8, except that the positive electrode current collector contained tin (Sn) at the concentrations shown in Table 6. The results are shown in Table 6.

[0121] [Table 6]

[0122] Table 6 shows that when a predetermined amount of Sn is included in the positive electrode current collector, the high-temperature cycle performance is significantly improved. This is because Sn precipitates at the grain boundaries, reducing corrosion of the positive electrode current collector at the grain boundaries. Furthermore, from lead-acid battery E26, it can be seen that a Sn content of 2.4% by mass or less is preferable. [Industrial applicability]

[0123] The lead-acid battery according to the present invention is suitable as a lead-acid battery whose charging and discharging are controlled by a PSOC, for example, as a starting power source or auxiliary lead-acid battery for vehicles controlled by an ISS, but its applications are not particularly limited. [Explanation of Symbols]

[0124] 1: Lead-acid battery, 2: Negative electrode plate, 3: Positive electrode plate, 4: Separator, 5: Positive electrode strap, 6: Negative electrode strap, 7: Positive electrode post, 8: Through connector, 9: Negative electrode post, 11: Electrode plate group, 12: Battery case, 13: Partition wall, 14: Cell chamber, 15: Cover, 16: Negative electrode terminal, 17: Positive electrode terminal, 18: Electrode cap

Claims

1. A group of electrode plates, an electrolyte, and a battery case containing the group of electrode plates and the electrolyte, A lead-acid battery equipped with, The electrode plate group comprises a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate. The extraction load (initial value) W1 when the electrode plate group of the fully charged lead-acid battery is withdrawn from the battery case is 1.8 times or more the weight W2 of the electrode plate group. The positive electrode plate includes a positive electrode current collector and a positive electrode material. At least the electrolyte and the positive electrode material contain phosphorus, The value obtained by dividing the sum of the amount of phosphorus (mol) contained in the electrolyte and the amount of phosphorus (mol) contained in the positive electrode material by the volume (L) of the electrolyte is between 8 mmol / L and 100 mmol / L. The electrolyte contains metal cations, The aforementioned metal cation includes sodium ions, A lead-acid battery in which the concentration of sodium ions in the electrolyte is 30 mmol / L or more.

2. The negative electrode plate includes a negative electrode current collector and a negative electrode material. The lead-acid battery according to claim 1, wherein the negative electrode material contains an organic shrinkage inhibitor having a sulfur element content of 3,000 μmol / g to 7,000 μmol / g.

3. The positive electrode current collector contains tin, The lead-acid battery according to claim 1, wherein the tin content in the positive electrode current collector is 1.0% by mass to 2.4% by mass.

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