Electrode group and lead-acid battery

Abstract

To provide an electrode group in a lead acid battery, in which the excellent charging acceptability is obtained and the decrease in electrolyte solution due to charging and discharging can be suppressed.SOLUTION: An electrode group 1 for a lead acid battery includes a positive electrode plate 10, a negative electrode plate 20, and a separator 30 disposed between the positive electrode plate 10 and the negative electrode plate 20. The negative electrode plate 20 includes a current collector and a negative electrode material supported by the current collector. The negative electrode material contains a carbon material. The separator 30 includes a base part including one surface and the other surface that face each other, a rib extending in one direction in the one surface, and a rib extending in a direction intersecting with the one direction in the other surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an electrode group, a lead-acid battery, and the like. [Background technology]

[0002] Lead-acid batteries are one of the conventional secondary batteries, and are widely used as secondary batteries for industrial and consumer use due to their reliability, low cost, etc. Lead-acid batteries are particularly in high demand as lead-acid batteries for automobiles, electric vehicles, power supply devices, etc.

[0003] For example, automotive lead-acid batteries are widely used for starting engines and powering electrical equipment. In recent years, as part of efforts to protect the environment and improve fuel efficiency, idle-stop systems (hereinafter referred to as "ISS") have begun to be implemented, which stop the engine when the vehicle is temporarily stopped and restart it when the vehicle starts moving. Lead-acid batteries used in ISSs frequently start and stop the engine, which increases the number of large-current discharges when the engine is started, and this overlaps with the use of electrical equipment, resulting in a large discharge load.

[0004] Automotive lead-acid batteries are charged using a constant voltage alternator. In recent years, alternator voltage settings have been lowered to prevent electrolyte loss due to water decomposition during charging. In addition to adopting such low charging voltages, power generation control systems have also been adopted, which "control alternator charging during driving based on the vehicle's driving state and the lead-acid battery's state of charge, thereby reducing engine load, improving fuel economy, and reducing CO2 emissions." This type of system makes it difficult for lead-acid batteries to charge and reach a fully charged state. Under these operating conditions, lead-acid batteries are often used in an over-discharged state, without being fully charged.

[0005] When a lead-acid battery is not fully charged and remains in a low charge state for a long time, a phenomenon known as sulfation occurs, in which lead sulfate, an inactive discharge product, accumulates on the electrodes (plates, etc.). In such a situation, the active material is difficult to reduce (difficult to charge), and it is known that battery performance, such as charge acceptance, decreases.

[0006] Furthermore, when complete charging is difficult, a stratification phenomenon occurs in which the concentration of dilute sulfuric acid, the electrolyte, differs between the upper and lower electrodes in a lead-acid battery. In this case, the concentration of dilute sulfuric acid increases in the lower electrode, causing sulfation. This reduces the reactivity of the lower electrode, causing the reaction to occur only in the upper electrode. As a result, the active material deteriorates, weakening the bonds between the active materials. This causes the active material to peel off from the current collector (e.g., the current collector grid) that supports it in the upper electrode, resulting in a decrease in battery performance, such as charge acceptance.

[0007] In response to this, as a means for improving charge acceptance, Patent Document 1 below discloses a technology relating to a negative electrode for a lead-acid battery obtained by using a negative electrode active material, a phenolic resin, and carbon black made from heavy oil. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-196191 Summary of the Invention [Problem to be solved by the invention]

[0009] Incidentally, in some cases, lead-acid batteries are required not only to have improved charge acceptance but also to suppress the loss of electrolyte due to charge and discharge.

[0010] An object of one aspect of the present disclosure is to provide an electrode group in a lead-acid battery that can achieve excellent charge acceptance and suppress loss of electrolyte due to charge and discharge.An object of another aspect of the present disclosure is to provide a lead-acid battery including the electrode group. [Means for solving the problem]

[0011] The present inventors have focused on improving charge acceptance by using a carbon material as a constituent component of the negative electrode material, but have found that in this case, the amount of electrolyte loss during charge and discharge tends to increase. In response to this, the present inventors have found that by adjusting the relative relationship between the ribs arranged on one side and the other side of the base portion of the separator, it is possible to obtain excellent charge acceptance while suppressing the loss of electrolyte during charge and discharge.

[0012] One aspect of the present disclosure relates to an electrode group for a lead-acid battery, comprising: a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, wherein the negative electrode has a current collector and a negative electrode material supported on the current collector, the negative electrode material containing a carbon material, and the separator has a base portion having one side and the other side facing each other, a rib extending in one direction on the one side, and a rib extending in a direction intersecting the one direction on the other side.

[0013] Such an electrode group can provide excellent charge acceptance in a lead-acid battery and can also suppress loss of electrolyte due to charge and discharge.

[0014] Another aspect of the present disclosure relates to a lead-acid battery including the above-described electrode group. [Effects of the Invention]

[0015] According to one aspect of the present disclosure, it is possible to provide an electrode group in a lead-acid battery that can achieve excellent charge acceptance and suppress loss of electrolyte due to charge and discharge. According to another aspect of the present disclosure, it is possible to provide a lead-acid battery including the electrode group. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a perspective view showing an example of an electrode group. [Figure 2] FIG. 2 is a plan view showing one surface of the separator. [Figure 3] FIG. 3 is a plan view showing the other surface of the separator. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present disclosure will be described, but the present disclosure is not limited to the following embodiments.

[0018] As used herein, a numerical range "A or greater" refers to a range exceeding A and A. A numerical range "A or less" refers to a range exceeding A and A. In the numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. In the numerical ranges described herein, the upper or lower limit of the numerical range may be replaced with a value shown in the examples. "A or B" may include either A or B, or may include both. Unless otherwise specified, the materials exemplified herein can be used alone or in combination of two or more. When multiple substances corresponding to each component are present in the composition, the content of each component in the composition refers to the total amount of the multiple substances present in the composition, unless otherwise specified. Because specific gravity varies with temperature, in this specification, it is defined as the specific gravity converted at 20°C.

[0019] The electrode group according to this embodiment is an electrode group for a lead-acid battery, and includes a positive electrode (e.g., a positive electrode plate), a negative electrode (e.g., a negative electrode plate), and a separator disposed between the positive and negative electrodes. The negative electrode includes a current collector and a negative electrode material supported on the current collector. The negative electrode material contains a carbon material. The separator includes a base portion having a first surface (one side) and a second surface (the other side) facing each other, a first rib extending in a first direction (one direction) on the first surface, and a second rib extending in a second direction intersecting the first direction on the second surface. That is, the axis of the first rib and the axis of the second rib intersect each other. For example, the first rib may contact the positive electrode (the first surface may face the positive electrode), and the second rib may contact the negative electrode (the second surface may face the negative electrode). The lead-acid battery according to this embodiment includes the electrode group according to this embodiment.

[0020] The electrode group according to this embodiment can provide excellent charge acceptance in a lead-acid battery while suppressing electrolyte loss during charge and discharge. While the factors that contribute to this effect are unclear, the following factors are cited as examples. However, the factors are not limited to these. Specifically, the first rib extends in a first direction on the first surface, and the second rib extends in a second direction intersecting the first direction on the second surface. This prevents the movement of bubbles generated by electrode reactions on at least one surface of the electrode facing the first surface and the electrode facing the second surface, making the bubbles more likely to remain on the electrode surface. This reduces the effective surface area of the electrode (the area contributing to the electrode reaction), thereby suppressing electrolyte loss. Furthermore, the presence of the rib separates the electrode from the base, thereby suppressing stratification and thus suppressing electrolyte loss. Therefore, using a carbon material as a component of the negative electrode material can improve charge acceptance while suppressing electrolyte loss.

[0021] Examples of the constituent material of the separator (constituent material of the substrate that constitutes the separator) include organic binders. Examples of organic binders include olefin resins, acrylic resins, urethane resins, and styrene resins. Examples of olefin resins include polyethylene and polypropylene. The separator does not need to contain glass.

[0022] The separator disposed between the positive electrode and the negative electrode may be at least partially disposed between the positive electrode and the negative electrode. The electrode group may include a plurality of separators. The separator may be in the form of a bag or a sheet.

[0023] The pouch-shaped separator can accommodate an electrode (positive electrode or negative electrode) and has an internal space for accommodating the electrode (positive electrode or negative electrode). For example, the electrode group according to this embodiment may have a pouch-shaped separator, and the negative electrode may be accommodated in the internal space of the separator. In the "bagged separator," the internal space may cover at least a portion (partially or entirely) of one side and the other side of the electrode, and when the electrode group is accommodated in a lead-acid battery, the internal space may support the electrode at the lower vertical position, thereby holding the electrode in the internal space. The pouch-shaped separator may have an opening for accommodating the electrode (an opening through which the electrode can be inserted). In the pouch-shaped separator, at least a portion (partially or entirely) of the portion located below the opening direction for accommodating the electrode (the height direction (e.g., vertical direction) of the battery case when the electrode group is accommodated in the lead-acid battery; the same applies below) may be sealed. The pouch-shaped separator may be configured by folding back a single substrate (the folded portion of the substrate is the sealed portion), or may be configured by multiple substrates, with the substrates joined together at a portion located lower in the opening direction (the joint between the substrates is the sealed portion). The pouch-shaped separator may have at least one (one end or both ends) of its ends (the side of the pouch-shaped separator when the electrode group is housed in the lead-acid battery) in a direction intersecting (e.g., perpendicular to) the opening direction and substantially parallel to the inner surface (main surface) of the separator, and the end may be sealed at the joint between the substrates. The joint between the substrates may be a welded portion, a crimped portion (mechanical seal portion), or the like. The pouch-shaped separator may have ribs on its inner and outer surfaces; for example, a first rib may be arranged on the outer surface and a second rib may be arranged on the inner surface.

[0024] The first rib is an elongated member extending in the first direction. The second rib is an elongated member extending in the second direction. In a pouch-shaped separator having first and second ribs, one of the first and second ribs may extend in the opening direction, and the other of the first and second ribs may extend in a direction intersecting (e.g., perpendicular to) the opening direction. When the electrode group is housed in a lead-acid battery, one of the first and second ribs may extend in the height direction of the battery case or may extend vertically. When the electrode group is housed in a lead-acid battery, the other of the first and second ribs may extend in a direction intersecting (e.g., perpendicular to) the height direction of the battery case or may extend horizontally. The expression "ribs extending in the height direction of the battery case when the electrode group is housed in the lead-acid battery" means that the ribs extend from the lower part (bottom) of the battery case to the upper part, and the ribs may extend in a direction perpendicular to the bottom surface of the battery case, or in a direction inclined with respect to a perpendicular to the bottom surface of the battery case (for example, in a direction inclined by ±45°, ±30°, or ±10° with respect to a perpendicular to the bottom surface of the battery case). The same applies to the expression "ribs extending in a direction intersecting the height direction of the battery case when the electrode group is housed in the lead-acid battery," and the ribs may extend in a direction inclined with respect to a direction orthogonal to a perpendicular to the bottom surface of the battery case (for example, in a direction inclined by ±45°, ±30°, or ±10° with respect to a direction orthogonal to the perpendicular to the bottom surface of the battery case).

[0025] The second rib extends in a second direction intersecting the first direction in which the first rib extends. The separator may have at least one first rib extending in the first direction on the first surface and at least one second rib extending in the second direction on the second surface. The first rib or the second rib may be arranged in a region facing the electrode material region of the electrode, or may be arranged in a region facing the electrode material region of the electrode and a region not facing the electrode material region of the electrode. The "electrode material region of the electrode" is the region in which the electrode material (positive electrode or negative electrode material) is arranged in the electrode (positive electrode or negative electrode).

[0026] The inclination angle of the second rib relative to the first rib (the inclination angle of the axis of the second rib relative to the axis of the first rib) is greater than 0° and less than 90°, and from the viewpoint of easily obtaining excellent charge acceptance and easily suppressing loss of electrolyte due to charge and discharge, may be 1° or greater, 5° or greater, 10° or greater, 30° or greater, 45° or greater, greater than 45°, 60° or greater, 75° or greater, 80° or greater, or 85° or greater. From the viewpoint of easily obtaining excellent charge acceptance and easily suppressing loss of electrolyte due to charge and discharge, the first rib and the second rib may be perpendicular to each other. When the separator is a bag-shaped separator, the inclination angle of the first rib relative to the opening direction of the bag-shaped separator may be less than 45°, 30° or less, 10° or less, 5° or less, 1° or less, or 0°, and the inclination angle of the second rib relative to the opening direction of the bag-shaped separator may be more than 45°, 60° or more, 75° or more, 80° or more, 85° or more, or 90°.

[0027] The first rib may extend from one end to the other end of the first surface (excluding the joint between the substrates on the inner surface of the bag-shaped separator). The first rib may be a continuous or discontinuous member and may extend continuously or intermittently from one end to the other end of the first surface. The second rib may be a continuous or discontinuous member and may extend continuously or intermittently from one end to the other end of the second surface (excluding the joint between the substrates on the inner surface of the bag-shaped separator). The second rib may be a continuous or discontinuous member and may extend continuously or intermittently from one end to the other end of the second surface. The first rib or the second rib may extend to the joint between the substrates on the inner surface of the bag-shaped separator.

[0028] The separator may have a plurality of first ribs on the first surface and a plurality of second ribs on the second surface. The plurality of first ribs may be spaced apart from one another in a direction perpendicular to the first direction, and may be arranged at approximately equal intervals. The plurality of second ribs may be spaced apart from one another in a direction perpendicular to the second direction, and may be arranged at approximately equal intervals. One first rib may intersect with the plurality of second ribs. One second rib may intersect with the plurality of first ribs. When the separator is a bag-shaped separator, the first ribs are arranged on the outer surface of the bag-shaped separator and the second ribs are arranged on the inner surface of the bag-shaped separator, and the first ribs extend in the opening direction of the bag-shaped separator, the first ribs may be arranged at both end portions of the first surface in the direction perpendicular to the opening direction and at a center between the both end portions. The first rib in the center may be disposed in a region facing the electrode material region of the electrode (e.g., positive electrode), and the first ribs at both ends may be disposed in regions not facing the electrode material region of the electrode (e.g., positive electrode).

[0029] The separator may have first ribs or second ribs with a spacing (spacing between first ribs or spacing between second ribs) within the following ranges, from the viewpoint of easily obtaining excellent charge acceptance and easily suppressing loss of electrolyte during charge and discharge. The spacing between the first ribs or second ribs may be 0.1 mm or more, 0.3 mm or more, 0.5 mm or more, 1 mm or more, 3 mm or more, 5 mm or more, 8 mm or more, 10 mm or more, more than 10 mm, or 11 mm or more. The spacing between the first ribs or second ribs may be 20 mm or less, 15 mm or less, 12 mm or less, 11 mm or less, 10 mm or less, 8 mm or less, 5 mm or less, 3 mm or less, 1 mm or less, or 0.5 mm or less. From these viewpoints, the spacing between the first ribs or second ribs may be 0.1 to 20 mm, 0.3 to 15 mm, or 0.5 to 11 mm. When the spacing between the first ribs and the spacing between the second ribs are different, the spacing between the first ribs and the second ribs may be within any of the ranges described above, for example, the spacing between the first ribs may be 1 to 20 mm, 5 to 15 mm, or 8 to 12 mm, and the spacing between the second ribs may be 0.1 to 10 mm, 0.3 to 5 mm, or 0.5 to 1 mm. For adjacent ribs A and B, the spacing between the ribs may be the distance (e.g., the shortest distance) between the part of rib A closest to rib B and the part of rib B closest to rib A.

[0030] The thickness T of the base portion, the height H1 of the first rib, the height H2 of the second rib, the ratio H1 / T of the height H1 of the first rib to the thickness T of the base portion, or the ratio H2 / T of the height H2 of the second rib to the thickness T of the base portion may be within the following ranges from the viewpoint of easily obtaining excellent charge acceptance and easily suppressing loss of electrolyte due to charge and discharge.

[0031] The thickness T of the base portion may be 0.01 mm or more, 0.05 mm or more, 0.1 mm or more, 0.15 mm or more, 0.2 mm or more, or 0.25 mm or more. The thickness T of the base portion may be 1.0 mm or less, 0.8 mm or less, 0.5 mm or less, 0.4 mm or less, 0.3 mm or less, or 0.25 mm or less. From these viewpoints, the thickness T of the base portion may be 0.01 to 0.5 mm, 0.05 to 0.4 mm, or 0.1 to 0.3 mm.

[0032] The height H1 of the first rib may be 0.1 mm or more, 0.3 mm or more, 0.5 mm or more, more than 0.5 mm, or 0.6 mm or more. The height H1 of the first rib may be 2.0 mm or less, 1.5 mm or less, 1.0 mm or less, 0.8 mm or less, or 0.6 mm or less. From these perspectives, the height H1 of the first rib may be 0.1 to 2.0 mm, 0.3 to 1.0 mm, 0.3 to 0.8 mm, or 0.5 to 1.0 mm. The heights of all the first ribs in the separator may be within these ranges.

[0033] The height H2 of the second rib may be 0.01 mm or more, 0.03 mm or more, 0.04 mm or more, or 0.05 mm or more. The height H2 of the second rib may be 1.0 mm or less, 0.8 mm or less, 0.5 mm or less, 0.3 mm or less, 0.2 mm or less, 0.1 mm or less, or 0.05 mm or less. From these perspectives, the height H2 of the second rib may be 0.01 to 1.0 mm, 0.03 to 0.3 mm, 0.03 to 0.1 mm, or 0.04 to 0.3 mm. The heights of all the second ribs in the separator may be within these ranges.

[0034] The ratio H1 / T may be 0.1 or more, 0.5 or more, more than 1.0, 1.5 or more, 2.0 or more, or 2.4 or more. The ratio H1 / T may be 5.0 or less, 4.0 or less, 3.0 or less, 2.5 or less, or 2.4 or less. From these viewpoints, the ratio H1 / T may be 0.1 to 5.0, 1.0 to 3.0, 1.0 to 2.5, or 2.0 to 3.0.

[0035] The ratio H2 / T may be 0.01 or more, 0.05 or more, 0.1 or more, 0.15 or more, or 0.2 or more. The ratio H2 / T may be 2.0 or less, 1.5 or less, 1.0 or less, less than 1.0, 0.8 or less, 0.5 or less, 0.3 or less, or 0.2 or less. From these viewpoints, the ratio H2 / T may be 0.01 to 2.0, 0.05 to 1.0, 0.05 to 0.5, or 0.1 to 1.0.

[0036] The electrode group may have a plurality of positive electrodes and a plurality of negative electrodes. The number of positive electrodes and negative electrodes in the electrode group may or may not be the same. When the number of positive electrodes and negative electrodes is not the same, the number of negative electrodes may be greater than the number of positive electrodes. The number of positive electrodes or negative electrodes in the electrode group may be 5 or more, 6 or more, 7 or more, or 8 or more. The number of positive electrodes or negative electrodes in the electrode group may be 10 or less, 9 or less, 8 or less, or 7 or less. The number of positive electrodes or negative electrodes in the electrode group may be 5 to 10, 6 to 9, or 7 to 8. At least one (one or both) of the outermost electrodes in the electrode group may be a negative electrode.

[0037] The positive electrode has a positive electrode current collector and a positive electrode material supported on the positive electrode current collector. The negative electrode has a negative electrode current collector and a negative electrode material supported on the negative electrode current collector. The positive electrodes and negative electrodes may be arranged alternately with a separator interposed between them. The positive electrode excluding the positive electrode current collector is referred to as the "positive electrode material," and the negative electrode excluding the negative electrode current collector is referred to as the "negative electrode material."

[0038] The positive electrode current collector serves as a conductive path for current from the positive electrode material and holds the positive electrode material. The negative electrode current collector serves as a conductive path for current from the negative electrode material and holds the negative electrode material. The negative electrode current collector may be the same as or different from the positive electrode current collector. Examples of materials constituting the current collector include lead alloys such as lead-calcium-tin alloys and lead-antimony-arsenic alloys. Depending on the application, selenium, silver, bismuth, etc. may be added to the current collector. The current collector has, for example, a lattice shape and may be a cast lattice, an expanded lattice, etc. The current collector can be obtained by forming a lead alloy into a lattice shape using a gravity casting method, an expanding method, a punching method, etc.

[0039] The plurality of positive electrodes may be electrically connected to one another by connecting the lugs provided on the positive electrode current collectors via straps. The positive electrode straps may be provided with positive electrode poles for connecting the positive electrodes to positive electrode terminals. The plurality of negative electrodes may be electrically connected to one another by connecting the lugs provided on the negative electrode current collectors via straps. The negative electrode straps may be provided with negative electrode poles for connecting the negative electrodes to negative electrode terminals.

[0040] The positive electrode material contains a lead component (Pb component) and may contain β-PbO2. The positive electrode material may contain α-PbO2 or may not contain α-PbO2. The positive electrode material can contain lead components other than PbO2 (e.g., PbSO4), additives, etc., as necessary.

[0041] Additives that can be contained in the positive electrode material include carbon materials, reinforcing short fibers (excluding carbon fibers), etc. Carbon materials include carbon black, graphite, carbon fibers, etc. Carbon black includes furnace black (e.g., oil furnace black), channel black, acetylene black, thermal black, ketjen black, etc. Reinforcing short fibers include acrylic fibers, polyethylene fibers, polypropylene fibers, polyethylene terephthalate fibers, etc.

[0042] The negative electrode material contains a lead component (Pb component) and may contain lead (Pb). The negative electrode material may contain porous spongy lead. The negative electrode material may contain a lead component other than lead (Pb) (e.g., PbSO4) as needed.

[0043] The negative electrode material contains a carbon material, such as carbon black, graphite, or carbon fiber. Examples of carbon black include furnace black (e.g., oil furnace black), channel black, acetylene black, thermal black, and ketjen black.

[0044] The content of the carbon material in the negative electrode material (negative electrode material before or after chemical formation) may be in the following ranges based on the total mass of the negative electrode material: From the viewpoint of easily obtaining excellent charge acceptance, the content of the carbon material may be 0.01% by mass or more, 0.05% by mass or more, 0.08% by mass or more, 0.09% by mass or more, 0.1% by mass or more, 0.15% by mass or more, 0.18% by mass or more, 0.2% by mass or more, 0.25% by mass or more, 0.27% by mass or more, 0.3% by mass or more, 0.35% by mass or more, 0.36% by mass or more, 0.4% by mass or more, or 0.45% by mass or more. From the viewpoint of easily suppressing loss of the electrolyte solution during charge and discharge, the content of the carbon material may be 1% by mass or less, 0.9% by mass or less, 0.8% by mass or less, 0.7% by mass or less, 0.6% by mass or less, 0.5% by mass or less, 0.45% by mass or less, 0.4% by mass or less, 0.36% by mass or less, 0.35% by mass or less, 0.3% by mass or less, 0.27% by mass or less, 0.25% by mass or less, 0.2% by mass or less, 0.18% by mass or less, 0.15% by mass or less, 0.1% by mass or less, or 0.09% by mass or less. From these viewpoints, the content of the carbon material may be 0.01 to 1% by mass, 0.08 to 0.5% by mass, 0.1 to 0.5% by mass, or 0.08 to 0.4% by mass.

[0045] The negative electrode material may contain additives (excluding carbon materials) as needed. Examples of additives that can be included in the negative electrode material include resins having sulfo groups and / or sulfonate groups, short reinforcing fibers (excluding carbon fibers), and barium sulfate. Examples of resins having sulfo groups and / or sulfonate groups include lignin sulfonic acid, lignin sulfonates (e.g., sodium lignin sulfonate), and condensates of phenols, aminoarylsulfonic acids, and formaldehyde (e.g., condensates of bisphenol, aminobenzenesulfonic acid, and formaldehyde). Examples of short reinforcing fibers include acrylic fibers, polyethylene fibers, polypropylene fibers, and polyethylene terephthalate fibers.

[0046] The negative electrode material may contain barium sulfate from the viewpoint of easily obtaining excellent charge acceptance and easily suppressing loss of electrolyte solution during charge and discharge. The particle size (e.g., average particle size) of barium sulfate (barium sulfate particles) in the negative electrode material (negative electrode material before or after chemical formation) may be within the following range from the viewpoint of easily obtaining excellent charge acceptance. The particle size of barium sulfate may be 100 nm or more, 200 nm or more, 300 nm or more, 400 nm or more, 500 nm or more, 600 nm or more, or 700 nm or more. The particle size of barium sulfate may be 2000 nm or less, 1500 nm or less, 1200 nm or less, 1000 nm or less, 800 nm or less, or 700 nm or less. From these viewpoints, the particle size of barium sulfate may be 100 to 2000 nm, 300 to 1500 nm, or 500 to 1000 nm. The particle size of barium sulfate can be measured, for example, by a laser diffraction particle size distribution analyzer.

[0047] Positive and negative electrode materials can be obtained by aging and drying an electrode material paste containing raw materials for the electrode material (positive or negative electrode material) to obtain an unformed electrode material, and then chemically forming the unformed electrode material. Positive and negative electrodes can be obtained by aging and drying an electrode material paste supported on a current collector to obtain an unformed electrode material, and then chemically forming the unformed electrode material. The electrode material paste may contain a solvent and / or sulfuric acid. Examples of the solvent include water (e.g., ion-exchanged water) and organic solvents. The unformed positive electrode material may contain tribasic lead sulfate as a main component. Examples of raw materials for the positive electrode material include lead powder and red lead (Pb3O4). The unformed negative electrode material may contain tribasic lead sulfate as a main component. Examples of raw materials for the negative electrode material include lead powder.

[0048] The lead-acid battery according to the present embodiment may include a plurality of electrode groups. The lead-acid battery according to the present embodiment may include the electrode group according to the present embodiment as at least one of the plurality of electrode groups.

[0049] The lead-acid battery according to this embodiment may include a battery case that houses the electrode group. The battery case is hollow and has an internal space that houses the electrode group. The lead-acid battery according to this embodiment may include a lid that seals the battery case. The lid may be provided with a control valve that controls the pressure inside the battery case, a positive electrode terminal that connects the positive electrode to the outside, and a negative electrode terminal that connects the negative electrode to the outside.

[0050] The lead-acid battery according to this embodiment may include an electrolyte. The electrolyte may be accommodated in a battery case. The electrolyte may contain sulfuric acid and may contain sulfate ions. The electrolyte may contain metal ions such as aluminum ions. The specific gravity of the electrolyte (before or after chemical formation) may be 1.23 to 1.35, 1.25 to 1.3, or 1.26 to 1.28.

[0051] The lead-acid battery according to this embodiment may have a configuration in which a first surface of the separator faces the positive electrode, a second surface of the separator faces the negative electrode, and the second rib on the second surface extends horizontally. In this configuration, the first rib on the first surface may extend vertically. An example of an electrode group and separator in such a lead-acid battery is shown using FIGS. 1 to 3. FIG. 1 is a perspective view showing an electrode group 1 as an example of an electrode group. As shown in FIG. 1, the electrode group 1 includes a positive electrode plate (positive electrode) 10, a negative electrode plate (negative electrode) 20, and a separator 30 disposed between the positive electrode plate 10 and the negative electrode plate 20. The positive electrode plate 10 includes a positive electrode current collector 12 and a positive electrode material 14. The negative electrode plate 20 includes a negative electrode current collector 22 and a negative electrode material 24. The separator 30 is a pouch-shaped separator, and the negative electrode plate 20 is housed in the internal space of the separator 30. The electrode group 1 has a structure in which positive electrode plates 10 and negative electrode plates 20 are alternately stacked with separators 30 interposed therebetween. In the electrode group 1, the ears 10a of the multiple positive electrode plates 10 are collectively welded together with a positive electrode strap 40 that is connected to a positive electrode terminal via a positive electrode pole. The ears 20a of the multiple negative electrode plates 20 are collectively welded together with a negative electrode strap 50 that is connected to a negative electrode terminal via a negative electrode pole.

[0052] FIG. 2 is a plan view showing the outer surface of separator 30, which is a pouch-shaped separator, as one side of the separator. FIG. 3 is a plan view showing the inner surface of separator 30, which is a pouch-shaped separator, as the other side of the separator. Separator 30 has a base portion 30a, a first rib 30b, and a second rib 30c. Base portion 30a has the outer surface and inner surface of the pouch-shaped separator as one and the other surfaces that face each other. First rib 30b extends in a first direction (up and down on the paper) on the outer surface of separator 30. Second rib 30c extends in a second direction (left and right on the paper) that is perpendicular to the first direction on the inner surface of separator 30.

[0053] An automobile, electric vehicle, or power supply device according to this embodiment is equipped with the lead-acid battery according to this embodiment. Examples of electric vehicles include electric forklifts and golf carts. Examples of power supply devices include uninterruptible power supplies (UPS), power supplies for disaster prevention (emergency) radios, and power supplies for telephones. This embodiment provides a lead-acid battery for an automobile, electric vehicle, or power supply device. [Example]

[0054] Hereinafter, the present disclosure will be described more specifically with reference to examples and comparative examples, but the present disclosure is not limited to the following examples.

[0055] <Preparation of negative electrode plate> Based on the total mass of the lead powder, 0.2 mass% of lignin, a carbon material (oil furnace black), and 1.0 mass% of barium sulfate (average particle size: 700 nm) were added to the lead powder and then dry-mixed. The blending amount of the carbon material, based on the total mass of the lead powder, was 0.1 mass% in Example 1, 0.2 mass% in Example 2 and Comparative Examples 1 and 2, 0.3 mass% in Example 3, 0.4 mass% in Example 4, and 0.5 mass% in Example 5. Next, dilute sulfuric acid (specific gravity: 1.26) and water were added and kneaded to prepare a negative electrode material paste. The negative electrode material paste was filled into a 0.9 mm thick expanded current collector (lead-calcium-tin alloy). Next, the mixture was left to age for 18 hours in an atmosphere at 50°C and 95% humidity, and then dried in an atmosphere at 50°C to obtain an unformed negative electrode plate.

[0056] <Preparation of positive electrode plate> 0.01% by mass of reinforcing short fibers (polyethylene fibers) based on the total mass of the lead powder was added to the lead powder and then dry-mixed. Next, dilute sulfuric acid (specific gravity: 1.26) and water were added and kneaded to prepare a positive electrode paste. The positive electrode paste was filled into a 1.1 mm thick expanded current collector (cast grid, lead-calcium-tin alloy). Next, it was left to age for 18 hours in an atmosphere at 50°C and 95% humidity, and then dried in an atmosphere at 50°C to obtain an unformed positive electrode plate.

[0057] <Preparing the separator> Examples 1 to 5 A long sheet-like material (constituent material: polyethylene, base thickness T: 0.25 mm) having multiple long ribs on each of a first surface and a second surface facing each other was prepared. The first ribs on the first surface were ribs arranged to extend vertically in a lead-acid battery described below, extending from one end to the other in the longitudinal direction of the sheet-like material and arranged at approximately equal intervals (interval: 11 mm) from one end to the other in the lateral direction of the sheet-like material. The height H1 of the first ribs was 0.6 mm. The second ribs on the second surface were ribs arranged to extend horizontally in a lead-acid battery described below, extending from one end to the other in the lateral direction of the sheet-like material and arranged at approximately equal intervals (interval: 0.5 mm) from one end to the other in the longitudinal direction of the sheet-like material. The height H2 of the second ribs was 0.05 mm. The first ribs and the second ribs were perpendicular to each other.

[0058] The sheet was folded lengthwise so that the second rib was positioned on the inside, and then both ends of the sheet in the short direction (extending direction of the second rib) were mechanically sealed to produce a pouch-shaped separator. The length of the pouch-shaped separator in the longitudinal direction of the first rib was 117 mm, and the length of the pouch-shaped separator in the direction perpendicular to the longitudinal direction of the first rib (longitudinal direction of the second rib) was 115 mm.

[0059] (Comparative Example 1) A bag-shaped separator was produced in the same manner as in the example, except that a sheet-like material having the same configuration as the above-mentioned sheet-like material was used, except that no ribs were arranged on the second surface.

[0060] (Comparative Example 2) A bag-shaped separator was produced in the same manner as in the examples, except that a sheet-like material having the same configuration as the above-mentioned sheet-like material was used, except that the second rib on the second surface was a rib similar to the first rib on the first surface (a rib extending in the longitudinal direction of the sheet-like material).

[0061] <Making a lead-acid battery> The unformed negative electrode plate was inserted into the internal space of the pouch-shaped separator to obtain a negative electrode component. Next, eight negative electrode components and seven unformed positive electrode plates were stacked so that the unformed positive electrode plates and the negative electrode components were alternately stacked. Subsequently, the lugs of the plates with the same polarity were welded together using the cast-on-strap (COS) method to form a plate assembly. This plate assembly was inserted into a battery case to assemble a 2V single-cell battery (corresponding to a B24-size single cell specified in JIS D 5301). After injecting an electrolyte (dilute sulfuric acid) into the battery, it was subjected to formation in a water tank at 40°C for 20 hours at a current of 16 A to obtain a lead-acid battery.

[0062] <Carbon material content> To measure the carbon content based on the total mass of the negative electrode material, a lead-acid battery was prepared using the above-described procedure. The negative electrode plate was then removed from the battery. The negative electrode plate was then immersed in a nitric acid / hydrogen peroxide solution and filtered. The filtered residue was then immersed in a mannitol solution and filtered. The filtered residue was then immersed in a sodium carbonate solution and filtered. The filtered residue was then washed with hydrochloric acid and then filtered. The filtered residue was then washed with pure water. The washed solution was then filtered, and the residue was dispersed in acetone and filtered through a stocking to obtain a filtrate. Finally, the filtrate was dried and the carbon content was determined by measuring the TG / DTA thermal loss. The results are shown in Table 1.

[0063] <Evaluation of battery characteristics> (Charging acceptance) Charge acceptance was measured by measuring the current value 5 seconds after the start of charging when the battery's state of charge was 90% (a state in which 10% of the battery capacity was discharged from a fully charged state and then constant-voltage charged at 2.33 V). The charge acceptance (current value) of Comparative Example 1 was set at 100 and evaluated relative to the current value. The higher the charge acceptance, the better the battery, and the battery was scored according to the following criteria. The results are shown in Table 1. {Grading criteria} 6 points: Charging acceptance is 160 or higher 5 points: Charge acceptance is between 150 and 160 4 points: Charge acceptance is between 130 and 150 3 points: Charging acceptance is between 110 and 130 2 points: Charging acceptance is 90 or more but less than 110 1 point: Charge acceptance less than 90

[0064] (ISS life and fluid loss) The number of cycles required to reach the end of the battery life was measured as the ISS life using a method conforming to the Japanese Industrial Standards Idling Stop Life Test (JIS D 5306). The amount of electrolyte loss was measured as the change in the amount of electrolyte loss (amount of electrolyte loss; difference in mass of electrolyte due to charge and discharge) before the test and after 28,800 charge and discharge cycles in the life test. The ISS life and amount of electrolyte loss for Comparative Example 1 were evaluated relative to 100. The longer the ISS life (number of cycles), the more durable the battery is evaluated to be. The smaller the amount of electrolyte loss, the better the battery is, and the battery was scored according to the amount of electrolyte loss using the following criteria. The results are shown in Table 1. {Grading criteria} 6 points: Liquid loss is 70 or less 5 points: Liquid loss is over 70 and less than 80 4 points: Liquid loss is over 80 and less than 100 3 points: Liquid loss is over 100 and less than 120 2 points: Liquid loss is over 120 and less than 140 1 point: Loss of more than 140

[0065] (comprehensive evaluation) The lead-acid batteries were evaluated based on the total score of the above-mentioned scoring results for charge acceptance and amount of electrolyte loss. A total score of 7 or more was judged to be a good lead-acid battery. The results are shown in Table 1.

[0066] [Table 1] [Explanation of symbols]

[0067] 1...electrode group, 10...positive electrode plate, 10a, 20a...lug portion, 12...positive electrode current collector, 14...positive electrode material, 20...negative electrode plate, 22...negative electrode current collector, 24...negative electrode material, 30...separator, 30a...base portion, 30b...first rib, 30c...second rib, 40...positive electrode side strap, 50...negative electrode side strap.

Claims

1. a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; the negative electrode has a current collector and a negative electrode material supported on the current collector, the negative electrode material contains a carbon material, the separator has a base portion having one surface and another surface facing each other, a first rib extending in one direction on the one surface, and a second rib extending in a direction intersecting the one direction on the other surface, the one surface faces the positive electrode, the other surface faces the negative electrode, An electrode group for a lead-acid battery, wherein a ratio H2 / T of a height H2 of the second rib to a thickness T of the base portion is 0.01 to 2.

0.

2. The separator is bag-shaped, The electrode group according to claim 1 , wherein the negative electrode is accommodated in an internal space of the separator.

3. The electrode group according to claim 1 , wherein the first rib on the one surface and the second rib on the other surface are perpendicular to each other.

4. The electrode group according to any one of claims 1 to 3, wherein the negative electrode material further contains barium sulfate.

5. A lead-acid battery comprising the electrode group according to any one of claims 1 to 4.

6. A lead-acid battery as described in claim 5, wherein the second rib on the other side extends horizontally.

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