Lead-acid battery

Abstract

DEPCT64 A lead-acid battery consists of a positive electrode plate, a negative electrode plate, and a separator. It is placed between the positive and negative electrode plates and a separating electrolyte solution. There will be at least a ridge-like structure on the negative electrode side; the electrolyte solution will contain ions. The properties of aluminum and the concentration of aluminum ions in the electrolyte solution will... Not less than 0.02 mol / L and not more than 0.25 mol / L. -----------------------------------------------------------

Description

lead acid battery

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

[0002] Lead-acid batteries are used in a variety of applications, including automotive and industrial applications, and include a negative electrode plate, a positive electrode plate, a separator interposed between the negative and positive electrode plates, and an electrolyte.

[0003] The electrolyte generally uses an aqueous sulfuric acid solution (see Patent Document 1), which also proposes adding aluminum ions to the electrolyte.

[0004] On the other hand, separators having ribs are sometimes used. Patent Document 2 proposes a separator for a flooded lead-acid battery that includes a main rib and a mini-rib formed on the surface opposite to the main rib.

[0005] JP 2016-152130 A JP 2015-216125 A

[0006] Lead-acid batteries are sometimes used in a partially charged state known as PSOC (Partial State of Charge). For example, lead-acid batteries are used in PSOC in charge-controlled vehicles and idle-stop (IS) vehicles. Therefore, lead-acid batteries are required to have excellent life performance in cycle tests under PSOC conditions (hereinafter referred to as PSOC life performance). Using an electrolyte containing aluminum ions improves PSOC life performance to some extent, but reduces charge acceptance after overdischarge.

[0007] One aspect of the present invention relates to a lead-acid battery including a positive electrode plate, a negative electrode plate, a separator interposed between the positive electrode plate and the negative electrode plate, and an electrolyte, wherein the separator has a rib on at least the negative electrode plate side, the electrolyte contains aluminum ions, and a concentration of the aluminum ions in the electrolyte is 0.02 mol / L or more and 0.25 mol / L or less.

[0008] In a lead-acid battery, excellent PSOC life performance can be ensured and a decrease in charge acceptance after overdischarge can be suppressed.

[0009] 1 is a partially cutaway exploded perspective view showing the appearance and internal structure of a lead-acid battery according to one aspect of the present invention.

[0010] A lead-acid battery according to one aspect of the present invention 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 separator includes a rib (first rib) on at least the negative electrode plate side. The electrolyte contains aluminum ions, and the concentration of the aluminum ions in the electrolyte is 0.02 mol / L or more and 0.25 mol / L or less.

[0011] In lead-acid batteries, metal ions such as sodium ions and aluminum ions have traditionally been added to the electrolyte solution, for example, sodium ions suppress osmotic short circuits, and aluminum ions improve PSOC life performance.

[0012] Furthermore, in lead-acid batteries, lead sulfate is produced at both the positive and negative electrodes during discharge, and water is produced at the positive electrode. Meanwhile, metallic lead, lead dioxide, and sulfuric acid are produced from lead sulfate and water during charging. Adding aluminum ions to the electrolyte reduces the size of the lead sulfate precipitated during discharge and improves the reduction of lead sulfate to metallic lead during charging. As a result, the amount of lead sulfate that accumulates without reduction is reduced, improving PSOC life performance to some extent. However, as PSOC life increases, the amount of accumulated lead sulfate inevitably increases, reducing the specific gravity of the electrolyte. This decrease in the specific gravity of the electrolyte is particularly noticeable during overdischarge. When the specific gravity of the electrolyte decreases, aluminum ions contained in the electrolyte precipitate as aluminum hydroxide, increasing the resistance of the electrolyte. Consequently, charge acceptance during overdischarge decreases. However, this decrease in charge acceptance during overdischarge does not occur even when sodium ions are added to the electrolyte; it is a unique issue when aluminum ions are added to the electrolyte, and has not been previously known.

[0013] In the above aspect of the present invention, when using an electrolyte containing aluminum ions at a concentration of 0.02 mol / L or more and 0.25 mol / L or less, a separator having a first rib at least on the negative electrode plate side is used. The first rib of the separator improves the diffusibility of the electrolyte near the negative electrode plate, thereby suppressing a decrease in the specific gravity of the electrolyte near the negative electrode plate. This suppresses the precipitation of aluminum hydroxide during overdischarge, reducing the resistance of the electrolyte and, as a result, suppressing a decrease in charge acceptance. Furthermore, suppressing a decrease in the specific gravity of the electrolyte suppresses the coarsening of lead sulfate, which, together with the effect of the aluminum ions, improves PSOC life performance.

[0014] The improvement in PSOC life performance due to the provision of the first rib is hardly observed when the aluminum ion concentration in the electrolyte is 0.01 mol / L. However, when the aluminum ion concentration in the electrolyte is 0.02 mol / L or more and 0.25 mol / L or less, the improvement in PSOC life performance due to the provision of the first rib becomes significantly greater than when the aluminum ion concentration is 0.01 mol / L. Thus, when the aluminum ion concentration is 0.02 mol / L or more and 0.25 mol / L or less, the effect of providing the first rib becomes apparent and is fully exerted.

[0015] Adding aluminum ions to the electrolyte extends the PSOC life. As a result, the specific gravity of the upper part of the electrolyte decreases due to the accumulation of lead sulfate and stratification of the electrolyte. Therefore, at the end of life, lead ions in the electrolyte are reduced on the negative electrode side, causing metallic lead to precipitate in the form of dendrites, making permeation short circuits more likely to occur. In contrast, in the above-described aspect of the present invention, the aluminum ions reduce the particle size of lead sulfate, and the first rib on the negative electrode side of the separator improves the diffusibility of the electrolyte near the negative electrode, thereby suppressing the decrease in the specific gravity of the electrolyte. Therefore, the PSOC life is extended, and even under conditions that make permeation short circuits more likely to occur at the end of life, the increase in lead ion concentration in the electrolyte can be suppressed, thereby preventing permeation short circuits.

[0016] From the viewpoint of further improving charge acceptance after overdischarge, the concentration of aluminum ions in the electrolyte is preferably 0.02 mol / L or more and 0.20 mol / L or less.

[0017] The aluminum ion concentration in the electrolyte is determined by inductively coupled plasma (ICP) emission spectrometry of the electrolyte taken out of a fully charged lead-acid battery. More specifically, atomic absorption spectrometry is performed using an ICP emission spectrometer (Shimadzu Corporation, ICPS-8000), and the aluminum ion concentration is determined using a calibration curve.

[0018] In this specification, the fully charged state of a lead-acid battery refers to a state in which, for a flooded battery, the battery is charged in a water tank at 25°C at a constant current of 0.2 CA until a voltage of 2.5 V / cell is reached, followed by a further constant current charge of 0.2 CA for 2 hours. For a valve-regulated battery, the fully charged state refers to a state in which the battery is charged in an air tank at 25°C at a constant current and constant voltage of 0.2 CA to a voltage of 2.23 V / cell, and charging is terminated when the charging current during constant voltage charging drops to 1 mCA or less. Note that, in this specification, 1 CA is the current value (A) that is the same as the nominal capacity (Ah) of the battery. For example, for a battery with a nominal capacity of 30 Ah, 1 CA is 30 A, and 1 mCA is 30 mA.

[0019] The separator preferably further includes a rib (second rib) on the positive electrode plate side, which can suppress oxidation degradation of the separator.

[0020] The separator may be bag-shaped. When a bag-shaped separator is used, the electrolyte tends to stagnate. However, providing a first rib and a second rib increases the diffusibility of the electrolyte, further improving PSOC life performance and further suppressing a decrease in charge acceptance after overdischarge. The effect of suppressing permeation short circuits is also further enhanced. When a bag-shaped separator houses a positive electrode plate, stratification of the electrolyte is easily suppressed. When a bag-shaped separator houses a negative electrode plate, forming a first rib within the bag facilitates increasing the diffusibility of the electrolyte within the bag. Furthermore, unlike a positive electrode current collector, a negative electrode current collector elongates less during charge and discharge. Therefore, when a negative electrode plate is housed in a bag-shaped separator, separator tearing due to the elongation of the current collector is suppressed, thereby suppressing short circuits.

[0021] The lead-acid battery may include a fiber mat interposed between the positive electrode plate and the negative electrode plate. When the fiber mat is provided, the electrode plate is compressed by the fiber mat, reducing the amount of electrolyte around the electrode plate and reducing diffusibility. In the above aspect of the present invention, by providing a first rib at least on the negative electrode plate side of the separator, even when the fiber mat is provided, it is possible to retain the electrolyte near the negative electrode plate and improve the diffusibility of the electrolyte.

[0022] Hereinafter, the lead-acid battery according to the embodiment of the present invention will be described in detail for each of its main components, but the present invention is not limited to the following embodiment.

[0023] (Separator) The separator includes a base portion made of a microporous membrane and a rib protruding from at least one main surface of the base portion. The separator may include a rib protruding from one main surface of the base portion and a rib protruding from the other main surface of the base portion. The separator includes at least a rib protruding from one main surface, and this rib is arranged so as to be located on the negative electrode plate side. The rib located on the negative electrode plate side is referred to as the first rib. If the separator includes a rib protruding from the other main surface of the base portion, this rib is arranged on the positive electrode plate side (i.e., facing the positive electrode plate). The rib located on the positive electrode plate side is referred to as the second rib. The first rib can increase the diffusibility of the electrolyte near the negative electrode plate, thereby improving PSOC life performance and suppressing permeation short circuits. Furthermore, by suppressing the precipitation of aluminum hydroxide, a decrease in charge acceptance during overdischarge can be suppressed.

[0024] The separator is formed of a polymer material (but different from fibers). At least the base portion is a porous sheet, which may also be called a porous film. The separator may contain a filler (e.g., a particulate filler such as silica and / or a fibrous filler) dispersed in a matrix formed of the polymer material. The separator is preferably made of an acid-resistant polymer material. Such a polymer material is preferably a polyolefin such as polyethylene or polypropylene.

[0025] The average thickness of the base, the average height of the ribs, and the average pitch of the ribs described below are determined for separators that have been removed from fully charged lead-acid batteries, washed, and vacuum-dried (dried under a pressure lower than atmospheric pressure), as described above.

[0026] The average thickness of the base portion is, for example, 100 μm or more and 300 μm or less, and preferably 150 μm or more and 250 μm or less. When the average thickness of the base portion is in this range, it is easy to ensure the height of the first rib and, if necessary, the second rib while ensuring high capacity. The average thickness of the base portion is determined by measuring the thickness of the base portion at five arbitrarily selected points in a cross-sectional photograph of the separator and averaging the measured values.

[0027] The first ribs are formed on the surface of the separator facing the negative electrode plate. The average height of the first ribs is, for example, 0.05 mm or more, preferably 0.07 mm or more. When the average height of the first ribs is within this range, the electrolyte is more easily diffused. From the viewpoint of ensuring high capacity, the average height of the first ribs is, for example, 0.40 mm or less, preferably 0.20 mm or less. These lower and upper limits can be arbitrarily combined. In the separator, it is preferable that the first ribs are formed with such an average height at least in the region facing the negative electrode plate (preferably the region where the negative electrode material is present). For example, it is preferable that the first ribs with such an average height are formed on at least 70% of the area of ​​the region facing the negative electrode plate of the separator.

[0028] The height of the first rib refers to the distance from one main surface of the base portion at a predetermined position on the first rib to the top of the first rib. If the main surface of the base portion is not flat, the height of the first rib is the distance from the highest point on one main surface of the base portion to the top of the first rib at a predetermined position on the first rib when the separator is placed flat with the first rib side facing up. The average height of the first rib is calculated by averaging the heights of the first rib measured at 10 arbitrarily selected positions on the first rib on one main surface of the base portion.

[0029] The pattern of the first ribs on one main surface of the base portion is not particularly limited, and the first ribs may be formed randomly, or in a striped, curved, or lattice pattern. From the viewpoint of facilitating the diffusion of the electrolyte, it is preferable to form a plurality of first ribs arranged in a striped pattern on one main surface of the base portion. The orientation of the striped first ribs is not particularly limited, and, for example, the plurality of first ribs may be formed along the height direction or width direction of the negative electrode plate. Since the specific gravity of the electrolyte is likely to differ between the top and bottom of the electrode plate, it is preferable to form the plurality of first ribs in a striped pattern along the height direction of the negative electrode plate from the viewpoint of further enhancing the diffusibility of the electrolyte.

[0030] The negative and positive electrode plates usually have a tab at one end for extracting current from the electrode assembly. The vertical direction of the negative and positive electrode plates with the tab facing up is referred to as the height direction of the negative and positive electrode plates. The width direction of the negative and positive electrode plates is the direction perpendicular to the height direction and across the main surfaces of the negative and positive electrode plates.

[0031] The average pitch of the striped or lattice-shaped first ribs is, for example, 0.3 mm to 10 mm, preferably 0.5 mm to 5 mm. When the separator includes a region in which the first ribs are formed at an average pitch in this range, the effect of improving the diffusion of the electrolyte near the negative electrode plate is easily achieved. In the separator, the first ribs are preferably formed at such an average pitch in a region facing the negative electrode plate (preferably a region in which the negative electrode material is present). For example, it is preferable that the first ribs are formed at such an average pitch over 70% or more of the area of ​​the region facing the negative electrode plate. In regions that do not face the negative electrode plate, such as the end of the separator, or regions facing a region in which the negative electrode material of the negative electrode plate is not present, first ribs may or may not be formed, or multiple first ribs may be formed densely (e.g., at an average pitch of 0.5 mm to 5 mm).

[0032] The pitch of the first ribs is the distance between the tops of adjacent first ribs (more specifically, the distance between the centers of adjacent first ribs in a direction across the first ribs). The average pitch of the first ribs is determined by averaging the pitches of the first ribs measured at 10 arbitrarily selected locations. If the first ribs are densely formed in a region of the separator that does not face the negative electrode plate or a region facing a region where no negative electrode material is present, the average pitch can be calculated excluding this region. The average pitch of such partially densely formed first ribs can be calculated for this region in the same manner as described above.

[0033] The second ribs are formed on the surface of the separator facing the positive electrode plate. The average height of the second ribs is, for example, 0.3 mm or more, and preferably 0.4 mm or more. When the average height of the second ribs is within this range, oxidation degradation of the separator is easily suppressed. From the viewpoint of ensuring high capacity, the average height of the second ribs may be, for example, 1.0 mm or less, and may be 0.7 mm or less. These lower and upper limits can be arbitrarily combined. It is preferable that the second ribs are formed with such an average height in at least the region of the separator facing the positive electrode plate (preferably the region where the positive electrode material is present). For example, it is preferable that the second ribs with such an average height are formed on at least 70% of the area of ​​the region facing the positive electrode plate.

[0034] The average height of the second rib is determined in the same manner as for the first rib. The height of the second rib is the distance from the other main surface of the base at a predetermined position of the second rib to the top of the second rib.

[0035] The pattern and orientation of the second ribs are not particularly limited and may be selected from those described for the first ribs, for example. The average pitch of the striped or lattice-shaped second ribs is, for example, 1 mm to 15 mm, preferably 5 mm to 10 mm. When the separator includes a region in which the second ribs are formed at an average pitch within this range, the effect of suppressing oxidative degradation of the separator is further enhanced. In the separator, the second ribs are preferably formed at such an average pitch in a region facing the positive electrode plate (preferably a region where the positive electrode material is present). For example, it is preferable that the second ribs are formed with such an average pitch over 70% or more of the area of ​​the region facing the positive electrode plate. In regions not facing the positive electrode plate, such as the end of the separator, or regions facing a region where the positive electrode material is not present, second ribs may or may not be formed, or multiple second ribs may be formed densely (for example, at an average pitch of 0.5 mm to 5 mm). The pitch of the second ribs is the distance between the tops of adjacent second ribs (more specifically, the distance between the centers of adjacent second ribs in a direction crossing the second ribs). The average pitch of the second ribs can be calculated based on the average pitch of the first ribs.

[0036] A sheet-like separator may be sandwiched between the negative electrode plate and the positive electrode plate, or the negative electrode plate or the positive electrode plate may be housed in a bag-like separator, thereby interposing the separator between the negative electrode plate and the positive electrode plate. When a bag-like separator is used, the electrolyte is less likely to diffuse, but the provision of a first rib and a second rib improves the diffusibility. When the negative electrode plate is housed in a bag-like separator, the first rib makes it easier to increase the diffusibility of the electrolyte near the negative electrode plate. When the positive electrode plate is housed in a bag-like separator, stratification can be suppressed.

[0037] The separator can be obtained, for example, by extruding a resin composition containing a pore-forming agent (e.g., a solid pore-forming agent such as a polymer powder and / or a liquid pore-forming agent such as an oil) and a polymer material into a sheet, and then removing the pore-forming agent to form pores in the matrix of the polymer material. The ribs may be formed, for example, during extrusion molding, or by pressing the sheet with a roller having grooves corresponding to the ribs after molding or after removing the pore-forming agent. When a filler is used, it is preferably added to the resin composition.

[0038] (Electrolyte) The electrolyte is an aqueous solution containing sulfuric acid and aluminum ions. The electrolyte may be gelled as needed. The electrolyte may contain additives used in lead-acid batteries as needed.

[0039] The aluminum ion concentration in the electrolyte is 0.02 mol / L or more and 0.25 mol / L or less. If the aluminum ion concentration is less than 0.02 mol / L (e.g., 0.01 mol / L), the effect of improving PSOC life performance by the first rib cannot be fully exhibited. Furthermore, if the aluminum ion concentration is less than 0.02 mol / L (e.g., 0.01 mol / L), the effect of improving charge acceptance after overdischarge by providing the first rib cannot be obtained. If the aluminum ion concentration exceeds 0.25 mol / L, the charge acceptance after overdischarge decreases significantly. From the viewpoint of ensuring high charge acceptance after overdischarge, the aluminum ion concentration in the electrolyte is preferably 0.02 mol / L or more and 0.20 mol / L or less. From the viewpoint that the effect of the first rib in suppressing the decrease in charge acceptance after overdischarge is easily manifested, it is preferable that the concentration of aluminum ions in the electrolyte be 0.05 mol / L or more (e.g., 0.05 mol / L or more and 0.25 mol / L or less, or 0.05 mol / L or more and 0.20 mol / L or less).

[0040] The aluminum ions can be contained in the electrolytic solution by, for example, dissolving an aluminum compound in an aqueous solution containing sulfuric acid. The aluminum compound used is one that is soluble in an aqueous solution containing sulfuric acid. Examples of such compounds include aluminum salts of inorganic acids, and aluminum sulfate is preferred.

[0041] The specific gravity of the electrolyte at 20°C in a lead-acid battery in a fully charged state after formation is, for example, 1.10 g / cm 3 1.35g / cm or more 3 The following is the result.

[0042] (Positive Electrode Plate) Positive electrode plates for lead-acid batteries are classified into paste type and clad type. Paste type positive electrode plates include a positive electrode current collector and a positive electrode material. The positive electrode material is held by the positive electrode current collector. In the paste type positive electrode plate, the positive electrode material is the positive electrode plate excluding the positive electrode current collector. The positive electrode current collector may be formed in the same manner as the negative electrode current collector, and can be formed by casting lead or a lead alloy or processing a lead or lead alloy sheet.

[0043] A clad positive electrode plate includes multiple porous tubes, a metal core inserted into each tube, a positive electrode material filled into the tube with the metal core inserted, and a connecting seat connecting the multiple tubes. In a clad positive electrode plate, the positive electrode material is the positive electrode plate excluding the tubes, the metal core, and the connecting seat.

[0044] As the lead alloy used for the positive electrode current collector, a Pb—Ca-based alloy or a Pb—Ca—Sn-based alloy is preferred in terms of corrosion resistance and mechanical strength. The positive electrode current collector may have lead alloy layers with different compositions, or the number of alloy layers may be multiple. A Pb—Ca-based alloy or a Pb—Sb-based alloy is preferably used for the core metal. The positive electrode material contains a positive electrode active material (lead dioxide or lead sulfate) that generates capacity through an oxidation-reduction reaction. The positive electrode material may contain other additives as needed.

[0045] Unformed paste-type positive plates are obtained by filling a positive electrode current collector with positive electrode paste, aging it, and drying it, similar to the case of negative plates. The unformed positive plate is then formed. The positive electrode paste is prepared by kneading lead powder, additives, water, and sulfuric acid. Clad-type positive plates are formed by filling a tube with a core metal inserted with lead powder or lead powder slurry and connecting multiple tubes together.

[0046] (Negative Electrode Plate) The negative electrode plate of a lead-acid battery is composed of a negative electrode current collector and a negative electrode material. The negative electrode material is the negative electrode plate excluding the negative electrode current collector. The negative electrode current collector may be formed by casting lead (Pb) or a lead alloy, or may be formed by processing a lead or lead alloy sheet. Examples of processing methods include expanding and punching. Using a negative electrode grid as the negative electrode current collector is preferable because it is easy to support the negative electrode material.

[0047] The lead alloy used for the negative electrode current collector may be any of a Pb—Sb alloy, a Pb—Ca alloy, and a Pb—Ca—Sn alloy. These lead or lead alloys may further contain at least one element selected from the group consisting of Ba, Ag, Al, Bi, As, Se, Cu, etc. as an additive element.

[0048] The negative electrode material contains a negative electrode active material (lead or lead sulfate) that exhibits capacity through an oxidation-reduction reaction, and may also contain a shrinkage inhibitor, a carbonaceous material such as carbon black, barium sulfate, etc., and may also contain other additives as necessary.

[0049] The negative electrode active material in the charged state is sponge lead, but the unformed negative electrode plate is usually made using lead powder.

[0050] The negative electrode plate can be formed by filling a negative electrode current collector with a negative electrode paste, aging and drying the paste to produce an unformed negative electrode plate, and then chemically forming the unformed negative electrode plate. The negative electrode paste is produced by adding water and sulfuric acid to lead powder, an organic shrinkage inhibitor, and various additives as needed, and kneading them. In the aging process, the unformed negative electrode plate is preferably aged at a temperature higher than room temperature and at a high humidity.

[0051] The formation can be carried out by immersing an electrode plate assembly including unformed negative plates in an electrolyte containing sulfuric acid in a battery jar of a lead-acid battery and then charging the electrode plate assembly. However, the formation can also be carried out before assembling the lead-acid battery or the electrode plate assembly. The formation produces spongy lead.

[0052] (Fiber Mat) The lead-acid battery may further include a fiber mat interposed between the positive electrode plate and the negative electrode plate. When the fiber mat is disposed, the electrode plate is compressed by the fiber mat, making it difficult to retain the electrolyte around the electrode plate. In the above aspect of the present invention, the first rib is provided on the separator, making it easier to retain the electrolyte near the negative electrode plate and ensuring high diffusibility of the electrolyte.

[0053] Unlike separators, fiber mats are composed of a sheet-like fiber assembly. Examples of such fiber assembly include a sheet of entangled fibers that are insoluble in the electrolyte. Examples of such sheets include nonwoven fabrics, woven fabrics, and knitted fabrics.

[0054] Examples of fibers that can be used include glass fibers, polymer fibers (polyolefin fibers, acrylic fibers, polyester fibers such as polyethylene terephthalate fibers, etc.), pulp fibers, etc. Among the polymer fibers, polyolefin fibers are preferred.

[0055] The fiber mat may contain components other than fibers, such as an acid-resistant inorganic powder and a polymer as a binder. Examples of inorganic powder that can be used include silica powder, glass powder, and diatomaceous earth. However, the fiber mat is primarily composed of fibers. For example, 60% by mass or more of the fiber mat is made up of fibers.

[0056] The fiber mat may be disposed between the negative electrode plate and the positive electrode plate. Because a separator is also disposed between the negative electrode plate and the positive electrode plate, the fiber mat may be disposed between the negative electrode plate and the positive electrode plate, for example, between the negative electrode plate and the separator and / or between the separator and the positive electrode plate. From the viewpoint of suppressing stratification of the electrolyte, the fiber mat is preferably disposed so as to be in contact with the negative electrode plate. Furthermore, from the viewpoint of suppressing softening and shedding of the positive electrode active material, the fiber mat is preferably disposed so as to be in contact with the positive electrode plate. From the viewpoint of enhancing the effect of suppressing softening and shedding, the fiber mat is preferably disposed in a state where it is pressed against the positive electrode plate. However, in this case, the electrolyte near the negative electrode plate is likely to be insufficient. In this embodiment, the first rib is provided on the negative electrode plate side of the separator, so that the electrolyte can be secured near the negative electrode plate even when the fiber mat is disposed on the positive electrode plate side.

[0057] FIG. 1 shows the external appearance of an example of a lead-acid battery according to an embodiment of the present invention. The lead-acid battery 1 includes a battery case 12 that contains a plate pack 11 and an electrolyte (not shown). The battery case 12 is divided into multiple cell chambers 14 by partition walls 13. Each cell chamber 14 contains one plate pack 11. The opening of the battery case 12 is closed by a lid 15 that includes a negative electrode terminal 16 and a positive electrode terminal 17. The lid 15 is provided with a vent plug 18 for each cell chamber. When rehydrating, the vent plug 18 is removed and rehydration solution is added. The vent plug 18 may have the function of venting gas generated in the cell chambers 14 to the outside of the battery.

[0058] Each electrode plate group 11 is formed by stacking a plurality of negative electrode plates 2 and positive electrode plates 3 with separators 4 interposed therebetween. Here, a bag-shaped separator 4 is shown housing the negative electrode plates 2, but the shape of the separator is not particularly limited. In a cell chamber 14 located at one end of the battery case 12, a negative electrode shelf 6 that connects a plurality of negative electrode plates 2 in parallel is connected to a through-connector 8, and a positive electrode shelf 5 that connects a plurality of positive electrode plates 3 in parallel is connected to a positive electrode pole 7. The positive electrode pole 7 is connected to a positive electrode terminal 17 outside the lid 15. In a cell chamber 14 located at the other end of the battery case 12, a negative electrode pole 9 is connected to the negative electrode shelf 6, and a through-connector 8 is connected to the positive electrode shelf 5. The negative electrode pole 9 is connected to a negative electrode terminal 16 outside the lid 15. Each through-connector 8 passes through a through-hole provided in the partition wall 13 to connect the electrode plate groups 11 of adjacent cell chambers 14 in series.

[0059] EXAMPLES The present invention will be specifically described below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0060] Lead-acid batteries A1 to A5 and B1 (1) Preparation of negative electrode plate: Lead powder, water, dilute sulfuric acid, carbon black, and an organic shrinkage preventer were mixed to obtain a negative electrode paste. The negative electrode paste was filled into the mesh of an expanded lattice made of a Pb—Ca—Sn alloy as a negative electrode current collector, and the resulting negative electrode plate was aged and dried to obtain an unformed negative electrode plate. Sodium lignin sulfonate was used as the organic shrinkage preventer. The amounts of carbon black and the organic shrinkage preventer added were adjusted to 0.3% by mass and 0.2% by mass, respectively, based on 100% by mass of the negative electrode material.

[0061] (2) Preparation of Positive Electrode Plate: Lead powder, water, and sulfuric acid were mixed to prepare a positive electrode paste. The positive electrode paste was filled into the mesh of a Pb—Ca—Sn alloy expanded lattice as a positive electrode current collector, and the resulting mixture was aged and dried to obtain an unformed positive electrode plate.

[0062] (3) Preparation of Lead-Acid Battery: Each unformed negative electrode plate was housed in a pouch-shaped separator made of a polyethylene microporous membrane, and five unformed negative electrode plates and four unformed positive electrode plates per cell formed an electrode plate assembly. The separator had a first rib on the inside of the pouch and a second rib on the outside of the pouch. The separator had a plurality of striped first ribs and a plurality of striped second ribs, which were formed along the height direction of the negative electrode plate and the positive electrode plate, respectively. The average height of the first ribs was 0.1 mm, and the average pitch of the first ribs in the region facing the negative electrode plate was 1 mm. The average height of the second ribs was 0.4 mm, and the average pitch of the second ribs in the region facing the positive electrode plate was 10 mm. The average thickness of the separator base was 0.2 mm. The average height of the ribs, the average thickness of the base portion, and the average pitch of the ribs of the separator were values ​​determined for the separator before the lead-acid battery was fabricated, but they were almost the same as the values ​​measured by the above-mentioned procedure for the separator removed from the fabricated lead-acid battery.

[0063] The electrode plate assembly was inserted into a polypropylene battery case, an electrolyte was poured into the battery case, and chemical formation was performed inside the battery case to assemble flooded lead-acid batteries A1 to A5 and B1 with a nominal voltage of 12 V and a nominal capacity of 30 Ah (5-hour rate). The electrolyte used was a sulfuric acid solution with a specific gravity of 1.28 at 20°C, in which aluminum sulfate was dissolved. The amount of aluminum sulfate added was adjusted for each battery so that the aluminum ion concentration in the electrolyte would be the value shown in Table 2. Note that if the aluminum sulfate was completely dissolved when the electrolyte was prepared, the aluminum concentration (i.e., the aluminum sulfate concentration) when preparing the electrolyte would be approximately the same as the aluminum ion concentration in the electrolyte of a fully charged, pre-formed lead-acid battery.

[0064] Lead-acid battery B2 was assembled in the same manner as lead-acid battery A1, except that an electrolyte prepared without using aluminum sulfate was used.

[0065] Lead-acid battery B3 was assembled in the same manner as lead-acid battery B2, except that a pouch-shaped separator without a first rib was used.

[0066] Lead-acid batteries B4 to B9 were assembled in the same manner as lead-acid batteries B1 and A1 to A5, except that a pouch-shaped separator without a first rib was used.

[0067] [Evaluation 1: PSOC Life Performance] In accordance with SBA S 0101:2014, the lead-acid battery was charged and discharged under idle-stop conditions. Specifically, at 25°C, the following (a) to (c) were counted as one cycle, and the cycle count was determined until the end-of-discharge voltage reached 7.2 V or less. The PSOC life performance was evaluated as a ratio, with the number of cycles for lead-acid battery B3 being 100. Note that during charging and discharging, a 40- to 48-hour pause was performed every 3,600 cycles. (a) Discharge 1: Discharge at a current of 32 A for 59 seconds. (b) Discharge 2: Discharge at a current of 300 A for 1 second. (c) Charge: Charge at a limited current of 100 A and a voltage of 14.0 V for 60 seconds.

[0068] [Evaluation 2: Charge Acceptance After Overdischarge] A high-rate discharge characteristic test specified in JIS D5301:2006 was carried out using a fully charged lead-acid battery prepared using a chemical compound, in which the battery was discharged at a discharge current (150 A) at −15° C. until the terminal voltage reached 1 V per single cell, and the discharge time at this time (initial discharge time t0) was determined.

[0069] Next, the lead-acid battery was overdischarged under the conditions of Steps 1 and 2 shown in Table 1, and then recovery charged under the conditions of Steps 3 and 4. The lead-acid battery that had been overdischarged and then recovery charged was subjected to a high-rate discharge characteristic test in the same manner as above, and the discharge time (t1) was determined. The ratio t1 / t0 of the high-rate discharge performance before and after overdischarge was calculated and used as an index of charge acceptance after overdischarge. The results were expressed as a ratio, with the result of lead-acid battery B3 set to 100.

[0070]

[0071] [Evaluation 3: Penetration Short Circuit] The lead-acid batteries evaluated in Evaluation 1 were disassembled, the separators were removed, and the presence or absence of lead penetration marks was confirmed. The results for lead-acid batteries A1 to A5 and B1 to B9 are shown in Table 2.

[0072]

[0073] As shown in Table 2, lead-acid batteries A1 to A5, which have an aluminum ion concentration in the electrolyte of 0.02 mol / L or more and 0.25 mol / L or less and which use separators with first ribs, have significantly improved PSOC life performance (specifically, by 10 to 50%) compared to lead-acid batteries B1 and B2, which have an aluminum ion concentration of less than 0.02 mol / L. Lead-acid batteries A1 to A5 suppressed the decrease in charge acceptance after overdischarge, and lead-acid batteries A1 to A4 in particular showed results comparable to lead-acid battery B2, which uses an electrolyte that does not contain aluminum ions.

[0074] Furthermore, in comparison with lead-acid batteries B3 to B9 using separators without a first rib, the presence of the first rib in lead-acid batteries A1 to A5 significantly improved PSOC life performance. When the separator did not have a first rib, charge acceptance after overdischarge tended to decrease when the aluminum ion concentration was 0.02 mol / L or higher (lead-acid batteries B3 to B9). However, by providing the first rib, the decrease in charge acceptance after overdischarge was suppressed even at such an aluminum ion concentration.

[0075] The improvement in PSOC life performance due to the first rib is hardly observed when the aluminum ion concentration is 0.01 mol / L (comparison between Battery B4 and Battery B1). In contrast, when the aluminum ion concentration is 0.02 to 0.25 mol / L, the improvement effect due to the first rib (i.e., the effect after subtracting the effect of aluminum ions) becomes apparent, and the improvement in PSOC life performance due to the first rib is more than four times that when the aluminum ion concentration is 0.01 mol / L. The improvement in charge acceptance after overdischarge due to the first rib (i.e., the effect after subtracting the effect of aluminum ions) is not observed when the aluminum ion concentration is 0.01 mol / L (comparison between Battery B4 and Battery B1), but is particularly noticeable when the aluminum ion concentration is 0.05 mol / L or higher.

[0076] When the aluminum ion concentration was 0.02 mol / L or higher, penetration marks were observed when a separator without a first rib was used (lead-acid batteries B5 to B9).In contrast, in the lead-acid batteries A1 to A5, even when the aluminum ion concentration was in the same range, the provision of the first rib suppressed lead penetration and precipitation into the separator.

[0077] A lead-acid battery according to one aspect of the present invention is applicable to valve-regulated and flooded lead-acid batteries, and can be suitably used as a power source for starting automobiles, motorcycles, and the like.

[0078] 1: Lead-acid battery 2: Negative electrode plate 3: Positive electrode plate 4: Separator 5: Positive electrode shelf 6: Negative electrode shelf 7: Positive electrode column 8: Through-connector 9: Negative electrode column 11: Plate group 12: Battery case 13: Partition wall 14: Cell chamber 15: Lid 16: Negative electrode terminal 17: Positive electrode terminal 18: Vent plug

Claims

DEPCT641. A lead-acid battery consisting of: a positive electrode plate; a negative electrode plate; a separator placed between the positive and negative electrode plates; and an electrolyte solution, where the separator has at least a ribbed portion on the negative electrode side, the electrolyte solution contains aluminum ions and the concentration of aluminum ions in the electrolyte solution is 0.02 mol / L or more and 0.25 mol / L or less.

2. A lead-acid battery according to claim 1 where the concentration of The concentration of aluminum ions in the electrolyte solution shall be 0.02 mol / L or more and 0.20 mol / L or less.

3. Lead-acid battery according to claim 1 or 2 where the separator still has a ribbed structure on the positive electrode side.

4. Lead-acid battery according to any one of claims 1 to 3 where the separator is bag-shaped.

5. Lead-acid battery according to claim 4 where the separator stores the negative electrode.

6. Lead-acid battery according to claim 4 where the separator stores the positive electrode. 7.A lead-acid battery under any of the claims 1 through 6 where the ridge is constructed along the height direction of the negative electrode plate.

8. A lead-acid battery under any of the claims 1 through 7 which also incorporates a fibrous composite material placed between the positive and negative electrode plates.