Clad type positive electrode plate for lead-acid battery and lead-acid battery

Abstract

This clad positive-electrode plate for a lead storage battery comprises a plurality of porous tubes, metal cores accommodated within the tubes, a positive electrode material with which the tubes are filled, and a current collector that connects the longitudinal-direction ends of a plurality of the metal cores lined up in a row. The positive electrode material contains organic fibers. The density of the positive electrode material is 3.75 g / cm3 or less. The positive electrode material satisfies at least one of a condition (a), in which the number of organic fibers per unit volume (cm3) of the positive electrode material is 400-15,000 (inclusive), and a condition (b), in which the ratio of the organic fibers occupying the positive electrode material is 0.013-0.5 vol% (inclusive).

Description

Technical Field

[0001] The present invention relates to a clad-type positive electrode plate for a lead storage battery and a lead storage battery.

Background Art

[0002] Lead storage batteries are used in various applications, including in-vehicle and industrial applications. A lead storage battery includes a positive electrode plate, a negative electrode plate, and an electrolyte. As the positive electrode plate, a paste-type positive electrode plate, a clad-type positive electrode plate, etc. are used. Each electrode plate includes a current collector and an electrode material. From the viewpoint of imparting various functions, an additive may be added to a constituent member (for example, an electrode material) of the lead storage battery.

[0003] Patent Document 1 proposes a lead storage battery characterized in that in a lead storage battery in which the positive electrode material has a density of 3.1 g / cm 3 or more and contains an Sb element, the organic shrinkage inhibitor of the negative electrode material contains 3800 μmol / g or more of S element.

[0004] Patent Document 2 proposes a lead storage battery including a negative electrode plate containing an organic shrinkage inhibitor having an S element content of 3500 μmol / g or more, and one or more of a gelled electrolyte, an electrolyte held by a separator, or an electrolyte held by granular silica.

[0005] Patent Document 3 proposes a positive electrode plate for a lead storage battery in which a positive electrode active material mainly composed of lead powder is filled in a positive electrode grid body, and the positive electrode active material contains organic or glass short fibers and antimony.

[0006] Patent Document 4 proposes a lead storage battery including a positive electrode plate, a negative electrode plate, and an electrolyte, wherein the negative electrode material of the negative electrode plate contains graphite or carbon fiber and 1.1 mass% or more of barium element in terms of barium sulfate, and the positive electrode material of the positive electrode plate contains tin element.

[0007] It has also been proposed to adjust the density or specific surface area of the electrode material.

[0008] Patent Document 5 provides a lead-acid battery including a positive electrode and a negative electrode, where the positive electrode has a positive electrode current collector and a positive electrode material held by the positive electrode current collector, and the negative electrode has a negative electrode current collector and a negative electrode material held by the negative electrode current collector. The specific surface area of the positive electrode material is 10 m 2 / g or more, and the density of the positive electrode material is 3.8 g / cm 3 or more.

[0009] Patent Document 6 proposes a sealed lead-acid battery having a positive electrode in which a positive electrode active material having a density of 3.8 to 5.0 g / cm 3 is held in a grid formed of a lead alloy not containing antimony, and a sulfuric acid electrolyte having a density of 1.20 to 1.28 g / cm 3

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0011] In a lead-acid battery used in a charge-discharge cycle including deep discharge, when the charge-discharge cycle is repeated for a long time, the temperature of the battery rises. In a lead-acid battery provided with a clad-type positive electrode plate, when the density of the positive electrode material is relatively low, it has been found that a rapid voltage rise may occur during charging when a charge-discharge cycle including deep discharge is performed at a high temperature (for example, a temperature of 75°C or higher). For example, when the lead-acid battery is charged by a constant-voltage method, if a rapid voltage rise occurs during charging, it may be recognized that the set voltage of charging is reached early, and the charging ends, resulting in an undercharged state in reality.

Means for Solving the Problem

[0012] A first aspect of the present invention is a clad-type positive electrode plate for a lead-acid battery, The positive electrode plate includes a plurality of porous tubes, a grid housed in the tubes, a positive electrode material filled in the tubes, and a current collector connecting one end portions in the length direction of the plurality of grids arranged in a row. The positive electrode material includes organic fibers, The density of the positive electrode material is 3.75 g / cm 3 or less, The number of the organic fibers per unit volume (cm 3 ) of the positive electrode material is 400 or more and 15000 or less, and relates to a clad-type positive electrode plate for a lead-acid battery.

[0013] A second aspect of the present invention is a clad-type positive electrode plate for a lead-acid battery, The positive electrode plate includes a plurality of porous tubes, a grid housed in the tubes, a positive electrode material filled in the tubes, and a current collector connecting one end portions in the length direction of the plurality of grids arranged in a row. The positive electrode material includes organic fibers, The density of the positive electrode material is 3.75 g / cm 3 or less, The ratio of the organic fibers in the positive electrode material is 0.013% by volume or more and 0.5% by volume or less, and relates to a clad-type positive electrode plate for a lead-acid battery.

[0014] A third aspect of the present invention is a lead-acid battery, wherein the lead-acid battery includes at least one electrode plate group and an electrolyte, the electrode plate group includes at least one of the above-described clad positive electrode plate, at least one negative electrode plate, and a separator interposed between the clad positive electrode plate and the negative electrode plate, and relates to a lead-acid battery.

Advantages of the Invention

[0015] When a lead-acid battery including a clad positive electrode plate is charged and discharged in a charge-discharge cycle including deep discharge at a high temperature, an increase in voltage during charging can be reduced.

Brief Description of the Drawings

[0016]

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Modes for Carrying Out the Invention

[0017] In a lead-acid battery used in a charge-discharge cycle including deep discharge, when the charge-discharge is repeated for a long time, the temperature of the battery becomes high (for example, a temperature of 75 °C or higher). This is because during charging, it is likely to be in an overcharged state, generating heat, and during discharging, the resistance increases with deep discharge, resulting in increased heat generation.

[0018] In a lead-acid battery equipped with a clad type positive electrode plate, when the density of the positive electrode material is 3.75 g / cm 3 It has been clarified that when charge-discharge including deep discharge at high temperature is performed in the following cases, a rapid voltage rise occurs. Such a problem of voltage rise is a new problem that has not been known so far. The clad type positive electrode plate includes, for example, a plurality of porous tubes, a core metal housed in the tube, and a positive electrode material filled in the tube. When the density of the positive electrode material is small, sulfate ions easily penetrate into the positive electrode material. Although the details of the mechanism are not clear, it is considered that due to the action of sulfate ions that have penetrated to the inside, ions derived from components contained in the core metal diffuse into the positive electrode material, forming some resistance components, resulting in the above voltage rise.

[0019] A lead-acid battery may be charged by a constant-voltage method. In the constant-voltage method, charging is performed while detecting the voltage of the lead-acid battery (specifically, the terminal voltage). More specifically, in the state where the battery voltage at the initial stage of charging is low, the charging current is large, and as the charging progresses and the battery voltage rises, the charging current becomes small, and when the battery voltage reaches the set value, the charging ends. In such a charging method, if a rapid voltage rise as described above occurs during charging, although the charging is actually not progressing, it may be erroneously recognized that the battery voltage has reached the set value, and the charging may end. Since a lead-acid battery with charging completed is actually in an undercharged state, it is difficult to operate it for a long time even when the lead-acid battery is mounted on a device or equipment.

[0020] In view of the above, the lead-acid batteries according to the first and second aspects of the present invention each include at least one electrode plate group and an electrolyte. The electrode plate group includes at least one clad positive electrode plate, at least one negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate. The positive electrode plate includes a plurality of porous tubes, a grid housed in the tubes, a positive electrode material filled in the tubes, and a current collector connecting one end portion in the length direction of a plurality of grids arranged in a row. The positive electrode material includes organic fibers. The density of the positive electrode material is 3.75 g / cm 3 is as follows.

[0021] In the lead-acid battery according to the first aspect, (a) the number of organic fibers per unit volume (cm 3 ) of the positive electrode material is 400 or more and 15,000 or less.

[0022] In the lead-acid battery according to the second aspect, (b) the ratio of the organic fibers in the positive electrode material is 0.013% by volume or more and 0.5% by volume or less.

[0023] In the lead-acid batteries according to the first and second aspects, even when the density of the positive electrode material is 3.75 g / cm 3 or less, when charging and discharging are performed in a charge-discharge cycle including deep discharge at a high temperature (for example, 75°C), the voltage rise during charging can be reduced. Therefore, the occurrence rate of voltage rise in the lead-acid battery can be significantly reduced. Such an effect is obtained because the positive electrode material contains organic fibers so as to satisfy the above condition (a) or (b). Even when the density of the positive electrode material is small, the movement of ions in the positive electrode material is hindered by the organic fibers. More specifically, it is considered that the intrusion of sulfate ions into the vicinity of the grid is alleviated. Further, even when sulfate ions reach the vicinity of the grid and components contained in the grid elute, the movement of ions in the positive electrode material such as ions derived from this component is hindered, and the diffusion to the entire positive electrode material is considered to be reduced. It is considered that the above voltage rise is reduced by reducing the formation of resistance components in the positive electrode material.

[0024] In addition, in this specification, when charging and discharging are performed in a charge-discharge cycle including deep discharge at a high temperature (for example, 75°C), the voltage rise during charging may be simply referred to as "voltage rise in a high-temperature deep-discharge cycle".

[0025] On the other hand, in the case where the density of the positive electrode material in the clad-type positive electrode plate exceeds 3.75 g / cm 3 even if the positive electrode material does not contain organic fibers, the voltage rise in the high-temperature deep-discharge cycle does not become a problem. That is, it can be said that the voltage rise in the high-temperature deep-discharge cycle is a problem peculiar to the case where the density of the positive electrode material in the clad-type positive electrode plate is 3.75 g / cm 3 or less. In the first aspect and the second aspect of the present invention, such a peculiar problem can be solved by condition (a) or (b).

[0026] The present invention also includes a clad-type positive electrode plate for a lead storage battery that satisfies condition (a) or (b). Each of the clad-type positive electrode plates for a lead storage battery according to the third aspect and the fourth aspect of the present invention includes a plurality of porous tubes, a core metal housed in the tube, a positive electrode material filled in the tube, and a current collector that connects one end portion in the length direction of a plurality of core metals arranged in a row. The positive electrode material contains organic fibers. The density of the positive electrode material is 3.75 g / cm 3 or less. And the clad-type positive electrode plate for a lead storage battery according to the third aspect satisfies the above condition (a). The clad-type positive electrode plate for a lead storage battery according to the fourth aspect satisfies the above condition (b). By using such a clad-type positive electrode plate in a lead storage battery, the above-described effects as described in the first aspect or the second aspect can be obtained.

[0027] Each of the first aspect and the third aspect may satisfy condition (b) in addition to condition (a). In this case, the voltage rise in the high-temperature deep-discharge cycle can be more effectively reduced.

[0028] The unit volume (cm 3) The number of organic fibers per unit volume may be 800 or more. Also, the ratio of the organic fibers in the positive electrode material may be 0.026% by volume or more. In these cases, the occurrence rate of voltage increase during high-temperature deep discharge cycles can be further reduced.

[0029] The number of organic fibers per unit volume (cm 3 ) of the positive electrode material may be 10,000 or less. Also, the ratio of the organic fibers in the positive electrode material may be 0.32% by volume or less. In these cases, in the positive electrode material, a decrease in the bonding strength is suppressed and cracking is reduced, making it easier to ensure a higher initial capacity.

[0030] The organic fibers preferably include fibers having a specific gravity of 1.2 or more. In this case, the occurrence rate of voltage increase during high-temperature deep discharge cycles can be further reduced. This is presumably because the fibers are more easily dispersed uniformly throughout the positive electrode material, further restricting the movement of ions within the positive electrode material.

[0031] The organic fibers contain an oxygen element, and the content of the oxygen element in the organic fibers is preferably 10,000 μmol / g or more. In this case, the occurrence rate of voltage increase during high-temperature deep discharge cycles can be further reduced. When the organic fibers contain a large amount of oxygen element, the organic fibers are more likely to form hydrogen bonds with water molecules. As a result, the organic fibers are more easily dispersed uniformly throughout the positive electrode material, so the movement of ions within the positive electrode material is further restricted by the organic fibers, and it is considered that the occurrence rate of voltage increase during high-temperature deep discharge cycles is further reduced.

[0032] The content of the oxygen element in the organic fibers may be 35,000 μmol / g or less. In this case, oxidative decomposition of the organic fibers is suppressed even when exposed to the positive electrode potential, so high durability can be ensured.

[0033] The organic fiber preferably contains at least one selected from the group consisting of polyester fiber, acetalized polyvinyl alcohol fiber, polyurethane fiber, and cellulose fiber. These organic fibers have an appropriate specific gravity and are easily dispersed more uniformly throughout the positive electrode material. Therefore, it is considered that the movement of ions in the positive electrode material is further restricted by the organic fibers, and the occurrence rate of voltage increase during high-temperature deep discharge cycles is further reduced.

[0034] The density of the positive electrode material is preferably 3.7 g / cm 3 or less. In this case, the occurrence rate of voltage increase during high-temperature deep discharge cycles becomes higher, but even within such a range, by including organic fibers in the positive electrode material so as to satisfy at least one of the above conditions (a) and (b), the occurrence rate of voltage increase during high-temperature deep discharge cycles can be reduced.

[0035] From the viewpoint of easily ensuring a higher discharge capacity, the density of the positive electrode material is preferably 3.3 g / cm 3 or more.

[0036] The lead storage battery may be either a controlled valve type (sealed type) lead storage battery (VRLA type lead storage battery) or a liquid type (vented type) lead storage battery.

[0037] In this specification, the density of the positive electrode material, the number of organic fibers per unit volume, the ratio of organic fibers in the positive electrode material, the specific gravity of the organic fibers, and the content of oxygen element in the organic fibers are determined for the positive electrode plate taken out from the fully charged lead storage battery.

[0038] (Explanation of terms) (Positive electrode material) The clad-type positive electrode plate includes a plurality of porous tubes, a spine accommodated in each tube, a positive electrode material filled in the tubes, and a current collector that connects one end portion in the longitudinal direction of a plurality of spines arranged in a row. The clad-type positive electrode plate may further include a spine protector that connects a plurality of tubes. In the clad-type positive electrode plate, the positive electrode material is a portion excluding the tubes, the spine, the current collector, and the spine protector from the positive electrode plate. In the clad-type positive electrode plate, the spine and the current collector may be collectively referred to as a positive electrode current collector. A member such as a mat may be attached to the positive electrode plate. Since such a member (also referred to as an attached member) is used integrally with the positive electrode plate, it is included in the positive electrode plate. When the positive electrode plate includes an attached member (such as a mat), the positive electrode material is a portion excluding the tubes, the positive electrode current collector, the spine protector, and the attached member from the positive electrode plate.

[0039] (Density of the positive electrode material) The density of the positive electrode material is the density (g / cm 3 ) obtained by dividing the mass of the positive electrode material by the bulk volume of the positive electrode material determined by the mercury intrusion method. The density is determined for a predetermined amount of unground positive electrode material collected from the positive electrode plate taken out from the lead storage battery. The positive electrode material at this time is collected from one tube located near the center of the positive electrode plate.

[0040] (Number of organic fibers per unit volume of the positive electrode material) The number of organic fibers per unit volume (cm 3 ) of the positive electrode material is a numerical value obtained by dividing the number of organic fibers contained in the positive electrode material by the bulk volume (cm 3 ) of the positive electrode material determined by the mercury intrusion method. The number of organic fibers per unit volume (cm 3 ) of the positive electrode material is determined for a predetermined amount of unground positive electrode material used for calculating the density.

[0041] (Ratio of organic fibers in the positive electrode material) The ratio of the organic fiber in the positive electrode material is the ratio (volume %) of the total volume of the organic fiber contained in the positive electrode material to the bulk volume (cm 3 ) of the positive electrode material determined by the mercury intrusion method. The ratio of the organic fiber in the positive electrode material is determined for a predetermined amount of unground positive electrode material used for density calculation.

[0042] (fully charged state) The fully charged state of a flooded lead-acid battery is defined according to JIS D 5301:2019. More specifically, in a water tank at 25°C ± 2°C, with a current (A) of 0.2 times the value (unit: Ah) described as the rated capacity, the terminal voltage (V) during charging measured every 15 minutes or the electrolyte density converted to 20°C shows a constant value with three significant figures for three consecutive times. The state where the lead-acid battery is charged until then is defined as the fully charged state. Also, in the case of a valve-regulated lead-acid battery, the fully charged state means that in an air tank at 25°C ± 2°C, with a current (A) of 0.2 times the value (unit: Ah) described as the rated capacity, constant current constant voltage charging at 2.23 V / cell is performed, and the charging is terminated when the charging current during constant voltage charging reaches a value (A) of 0.005 times the value (unit: Ah) described as the rated capacity.

[0043] A fully charged lead-acid battery refers to a lead-acid battery that has been fully charged after formation. For a lead-acid battery after formation, it may be immediately after formation, or it may be performed after a certain period of time has passed since formation (for example, a lead-acid battery during use (preferably in the initial stage of use) after formation may be fully charged). The battery in the initial stage of use refers to a battery that has not passed much time since the start of use and has hardly deteriorated.

[0044] (vertical direction of the lead-acid battery or its components) In this specification, the vertical direction of a lead-acid battery or its components (such as electrode plates, battery cases, separators, etc.) means the vertical up-and-down direction of the lead-acid battery in the state where the lead-acid battery is used. Each of the positive and negative electrode plates is provided with an ear portion for connection to an external terminal. Although in some cases such as a horizontally placed controlled valve type lead-acid battery, the ear portion may be provided so as to protrude laterally from the side portion of the electrode plate, in many lead-acid batteries, the ear portion is usually provided so as to protrude upward from the upper portion of the electrode plate.

[0045] Hereinafter, the clad type positive electrode plate and the lead-acid battery according to the embodiments of the present invention will be described for each main component, but the present invention is not limited to the following embodiments.

[0046] [Clad type positive electrode plate] The clad type positive electrode plate includes a plurality of porous tubes, a core metal accommodated in the tubes, a positive electrode material filled in the tubes, and a current collecting portion that connects one end portion in the length direction of a plurality of core metals arranged in a row. Further, the clad type positive electrode plate usually includes a connecting seat that connects a plurality of tubes.

[0047] (Positive electrode material) The positive electrode material contains organic fibers. The positive electrode material usually contains a positive electrode active material (specifically, at least one of lead dioxide and lead sulfate) that exhibits capacitance by an oxidation-reduction reaction. The positive electrode material may contain other additives as necessary.

[0048] The density of the positive electrode material is 3.75 g / cm 3 The following. In this case, although there is a problem of voltage increase in the high-temperature deep discharge cycle due to the positive electrode material containing organic fibers, by satisfying at least one of the above conditions (a) and (b), the voltage increase in the high-temperature deep discharge cycle can be reduced. The density of the positive electrode material is 3.7 g / cm 3The following may be the case. In this case, the occurrence rate of voltage increase during high-temperature deep discharge cycles becomes even higher. However, even in this case, by satisfying at least one of the above conditions (a) and (b), the voltage increase during high-temperature deep discharge cycles can be reduced. From the viewpoint of easily ensuring a higher discharge capacity, the density of the positive electrode material is 3.3 g / cm 3 or more, which is preferable.

[0049] The number of organic fibers per unit volume (cm 3 ) of the positive electrode material is 400 or more. From the viewpoint of further reducing the occurrence rate of voltage increase during high-temperature deep discharge cycles, the number of organic fibers per unit volume (cm 3 ) of the positive electrode material is preferably 800 or more. The number of organic fibers per unit volume (cm 3 ) of the positive electrode material is 15000 or less, preferably 10000 or less, and more preferably 7500 or less or 7200 or less. When the density of the positive electrode material is small, the bonding strength decreases and cracking tends to occur easily. However, when the number of organic fibers is within such a range, a relatively high bonding strength can be ensured in the positive electrode material, and cracking is reduced, so that a higher initial capacity can be ensured. These lower limit values and upper limit values can be arbitrarily combined.

[0050] The ratio of organic fibers in the positive electrode material is 0.013% by volume or more. From the viewpoint of further reducing the occurrence rate of voltage increase during high-temperature deep discharge cycles, the ratio of organic fibers is preferably 0.026% by volume or more. The ratio of organic fibers is 0.5% by volume or less, preferably 0.32% by volume or less, and more preferably 0.25% by volume or less or 0.23% by volume or less. When the ratio of organic fibers is within such a range, a relatively high bonding strength can be ensured in the positive electrode material, and cracking is reduced, so that a higher initial capacity can be ensured. These lower limit values and upper limit values can be arbitrarily combined.

[0051] The organic fiber preferably contains fibers with a specific gravity of 1.2 or more (hereinafter sometimes referred to as the first fiber). In this case, since the dispersibility of the first fiber is high, the occurrence rate of voltage increase during high-temperature deep discharge cycles can be further reduced. From the viewpoint of further reducing the occurrence rate of voltage increase during high-temperature deep discharge cycles, the specific gravity of the first fiber is more preferably 1.25 or more or 1.26 or more. The specific gravity of the first fiber is, for example, 1.7 or less, and may be 1.6 or less or 1.5 or less. These lower limit values and upper limit values can be arbitrarily combined.

[0052] The organic fiber may contain fibers other than the first fiber (hereinafter sometimes referred to as the second fiber). However, from the viewpoint of ensuring high dispersibility of the organic fiber, the ratio of the first fiber in the total organic fiber contained in the positive electrode material is preferably higher. The ratio of the first fiber in the total organic fiber contained in the positive electrode material is preferably 60% by volume or more, more preferably 75% by volume or more, and even more preferably 90% by volume or more. The ratio of the first fiber in the total organic fiber is 100% by volume or less. The positive electrode material may contain only the first fiber as the organic fiber. The second fiber is an organic fiber with a specific gravity of less than 1.2 (for example, 0.8 or more and less than 1.2).

[0053] The organic fiber may contain an oxygen element. The content of the oxygen element in the organic fiber is, for example, 10,000 μmol / g or more, preferably 15,000 μmol / g or more, more preferably 17,000 μmol / g or more or 17,400 μmol / g or more, still more preferably 19,000 μmol / g or more or 20,000 μmol / g or more, and may be 20,800 μmol / g or more. When the content of the oxygen element is in such a range, the organic fiber is likely to form a hydrogen bond with water molecules, so that the dispersibility of the organic fiber in the positive electrode material can be further enhanced, and the occurrence rate of voltage rise during high-temperature deep discharge cycles can be further reduced. The content of the oxygen element in the organic fiber is, for example, 50,000 μmol / g or less, and may be 40,000 μmol / g or less. From the viewpoint of ensuring higher durability of the organic fiber, the content of the oxygen element in the organic fiber is preferably 35,000 μmol / g or less. These lower limit values and upper limit values can be arbitrarily combined.

[0054] The average fiber diameter of the organic fiber is, for example, 1 μm or more, and may be 5 μm or more or 10 μm or more. When the average fiber diameter is in such a range, it is easy to ensure higher dispersibility of the organic fiber in the positive electrode material. The average fiber diameter of the organic fiber is, for example, 50 μm or less, and may be 30 μm or less or 20 μm or less. When the average fiber diameter is in such a range, it is easy to ensure higher conductivity of the positive electrode material. These lower limit values and upper limit values can be arbitrarily combined.

[0055] The average fiber length of the organic fiber is, for example, 0.1 mm or more, and may be 0.5 mm or more or 1 mm or more, and may be 1.5 mm or more or 2 mm or more. When the average fiber length is in such a range, it is easy to ensure higher dispersibility in the positive electrode material. The average fiber length of the organic fiber is, for example, 10 mm or less, and may be 6 mm or less. When the average fiber length is in such a range, higher dispersibility of the organic fiber can be ensured, and it is easy to ensure higher conductivity of the positive electrode material. These lower limit values and upper limit values can be arbitrarily combined.

[0056] The average fiber diameter of the organic fiber is the average value of the maximum diameters of any 100 fibers of the organic fiber separated from the positive electrode material. The average fiber length of the organic fiber is the average value of the lengths of any 100 fibers of the organic fiber separated from the positive electrode material.

[0057] Examples of the organic fiber include polyester fiber, polyvinyl alcohol fiber (such as acetalized polyvinyl alcohol fiber), polyurethane fiber, acrylic fiber, polyacrylonitrile fiber, polyolefin fiber, polyvinyl chloride fiber, polystyrene fiber, polyamide fiber, and cellulose fiber. The cellulose fiber includes not only cellulose-made fiber but also fibers made of cellulose derivatives (such as cellulose ether and cellulose ester), rayon, and the like. The positive electrode material may contain one kind of these organic fibers or two or more kinds. From the viewpoint of having an appropriate specific gravity and easily ensuring higher dispersibility in the positive electrode material, polyester fiber, acetalized polyvinyl alcohol fiber, polyurethane fiber, and cellulose fiber are preferable, and polyester fiber, acetalized polyvinyl alcohol fiber, and cellulose fiber are more preferable.

[0058] (Others) The core metal is composed of, for example, a lead alloy. It is preferable to use a Pb-Sb-based alloy for the core metal. The Pb-Sb-based alloy may contain at least one of arsenic, selenium, bismuth, and tin, etc., as required.

[0059] The current collector is composed of, for example, a lead alloy. It is preferable to use a Pb-Sb-based alloy for the current collector. The Pb-Sb-based alloy may contain at least one of arsenic, selenium, bismuth, and tin, etc., as required.

[0060] The porous tube only needs to be able to accommodate the core metal inside and hold the positive electrode material. The porous tube is usually a tubular fiber aggregate. As the tubular fiber aggregate, a fiber aggregate knitted into a tube shape may be used, or a tubular non-woven fabric or woven fabric may be used. Examples of the fiber include inorganic fibers (such as glass fibers) and resin fibers. However, the fiber is not limited to these. The porous tube may be heat-treated as required. Also, in the porous tube, the tubular fiber aggregate may be impregnated with resin.

[0061] The length of the tube may be selected according to the length of the core metal. The outer diameter and thickness of the tube are selected, for example, according to the shape of the core metal or the application of the lead-acid battery.

[0062] The connecting bases are usually arranged at one end on the current collecting part side and the other end opposite to the current collecting part of the tube, respectively. More specifically, in the longitudinal direction of the tube, one end on the current collecting part side of the tube is usually fixed to the current collecting part by the upper connecting base. The other end of the tube is sealed by the lower connecting base. The upper connecting base is usually formed by integrally molding resin so as to cover the upper part of the core metal and the current collecting part. The lower connecting base is usually made of resin and is inserted into the opening at the other end of each tube. An ear for taking out electricity from the lead-acid battery is usually formed on the current collecting part.

[0063] The clad positive electrode plate is formed by forming an unformed positive electrode plate formed by accommodating a plurality of core metals, one end of which in the length direction is connected at the current collector portion, in a plurality of tubes respectively and filling the tubes with lead powder, and then subjecting the unformed positive electrode plate to formation. The order of accommodating the core metals and filling the lead powder is not particularly limited. More specifically, the unformed positive electrode plate is formed by accommodating each of the plurality of core metals in a tube, then fixing one end of the plurality of tubes and the current collector portion with an upper connecting seat, filling the tube with a mixture containing lead powder and organic fibers etc. from the opening at the other end of the tube, and sealing the opening at the other end of the plurality of tubes with a lower connecting seat. The lead powder contains at least lead monoxide. The lead powder may contain metallic lead. Also, lead powder and red lead may be used in combination.

[0064] The filling of the mixture into the tube may be either dry or wet. For example, in the dry case, the dry mixture is filled into the tube as it is, and in the wet case, a slurry-like mixture is filled. The mixture contains, for example, lead powder, organic fibers, and additives as required. For example, the slurry-like mixture is prepared by mixing lead powder, organic fibers, water, sulfuric acid, and additives etc. as required. From the viewpoint of easily ensuring higher dispersibility of the organic fibers in the positive electrode material, it is preferable to use a slurry-like mixture. In particular, when the oxygen element content of the organic fibers is in the above range, the organic fibers can be more uniformly dispersed in the slurry-like mixture by the action of moisture.

[0065] The unformed positive electrode plate is further formed. Lead dioxide is generated by the formation. The formation can be carried out, for example, by charging a group of electrode plates including the unformed clad positive electrode plate in a state where the group of electrode plates is immersed in an electrolyte containing sulfuric acid in the battery case of a lead-acid battery. Such formation is called tank formation. However, not limited to the case of tank formation, the formation of the positive electrode plate may be carried out before the assembly of the group of electrode plates.

[0066] (Measurement of the density of the positive electrode material, and analysis of the positive electrode material and its constituent components) The following describes a method for measuring the density of a positive electrode material and a method for analyzing the positive electrode material or its constituent components. Prior to the measurement or analysis, a fully charged lead storage battery is disassembled to obtain a positive electrode plate to be analyzed. The obtained positive electrode plate is washed with water and dried to remove the electrolyte in the positive electrode plate. Next, the positive electrode material is separated from the positive electrode plate to obtain an unground sample (Sample A). Sample A is ground into a powder form if necessary and used for analysis.

[0067] (1) Measurement of the density of the positive electrode material For the unground Sample A, the density (bulk density) is determined by the mercury intrusion method using a mercury porosimeter. More specifically, first, a predetermined amount of the unground Sample A is taken and its mass is measured. This Sample A is put into the measurement container of the mercury porosimeter, evacuated under reduced pressure, and then filled with mercury at a pressure of 0.5 psia or more and 0.55 psia or less (≒ 3.45 kPa or more and 3.79 kPa or less) to measure the bulk volume of Sample A. The density of the positive electrode material is obtained by dividing the measured mass of Sample A by the bulk volume. Note that the bulk volume is the volume obtained by subtracting the injected volume of mercury from the volume of the measurement container. As the mercury porosimeter, an automatic porosimeter (AutoPore IV 9505) manufactured by Shimadzu Corporation is used.

[0068] (2) Analysis of organic fibers (2-1) Separation of organic fibers Take 5 g of Sample A whose bulk volume was measured in (1) above, and add 50 mL of nitric acid with a concentration of 20% by mass and 20 mL of hydrogen peroxide solution with a concentration of 300 g / L thereto. The resulting mixture is heated at 80 °C ± 5 °C until the lead component is completely dissolved. The resulting mixture is filtered to separate the solid content. The obtained solid content is dispersed in water to prepare a dispersion. Using a sieve, organic fibers and components other than organic fibers are separated from the dispersion.

[0069] (2-2) Number and ratio of organic fibers Count the number of all the organic fibers separated in (2-1) above, and the bulk volume (cm 3By dividing by [ [ ], the number of organic fibers per unit volume of the positive electrode material is obtained.

[0070] (2-3) Specific gravity of organic fiber A predetermined amount of the organic fiber separated in (2-1) above is sampled, and the specific gravity of the fiber is obtained by the density gradient tube method in accordance with JIS K7112-1999.

[0071] From the specific gravity of the fiber thus obtained, the number of all the organic fibers calculated in (2-2) above, and the mass of all these organic fibers, the total volume (cm 3 ) of the organic fibers contained in the sampled sample A is obtained. The total volume (cm 3 ) of the organic fibers is used to obtain the volume-based ratio (volume %) occupied in the bulk volume (cm 3 ) of the positive electrode material measured in (1). This ratio corresponds to the ratio (volume %) of the organic fiber in the positive electrode material.

[0072] (2-4) Content of oxygen element in organic fiber A predetermined amount of the organic fiber separated in (2-1) above is sampled. For the sampled organic fiber, CHN / O elemental analysis is performed using an organic trace analyzer to obtain the amount of oxygen (μmol / g) per 1 g of the organic fiber. As the organic trace analyzer, CE-440 manufactured by Exeter Analytical, Inc. is used.

[0073] (2-5) Type of organic fiber By combining the pyrolysis GC-MS spectrum of the organic fiber separated in (2-1) above, and the information obtained from the infrared absorption spectrum, ultraviolet-visible absorption spectrum, and NMR spectrum of the solution obtained by dissolving the organic fiber in a predetermined solvent, the type (material) of the organic fiber is specified.

[0074] (2-6) Average fiber diameter and average fiber length of organic fiber From the organic fibers separated in (2-1) above, 100 arbitrary fibers are selected, the maximum diameter of each fiber is measured, and the average fiber diameter of the organic fiber is obtained by averaging.

[0075] Select any 100 organic fibers separated in the above (2-1), and measure the length of each fiber. The length of the fiber is the length of the center line of the fiber. By averaging the measured lengths of the fibers, the average fiber length of the organic fibers is obtained.

[0076] (Negative electrode plate) The negative electrode plate includes, for example, a negative electrode material and a current collector that holds the negative electrode material. The negative electrode material is the part obtained by removing the current collector from the negative electrode plate. Members such as a mat and a pasting paper may be attached to the negative electrode plate. Since such a member (also referred to as an attachment member) is used integrally with the negative electrode plate, it is included in the negative electrode plate. When the negative electrode plate includes an attachment member (such as a mat or a pasting paper), the negative electrode material is the part obtained by removing the current collector and the attachment member from the negative electrode plate.

[0077] In addition, when a separator and a mat are used in combination in the electrode plate group, and when a mat mainly made of a non-woven fabric is attached to the negative electrode plate, the thickness of the negative electrode plate is the thickness including the mat. This is because the mat is used integrally with the negative electrode plate. However, when a mat is attached to the separator, the thickness of the mat is included in the thickness of the separator.

[0078] The negative electrode current collector may be formed by casting lead (Pb) or a lead alloy, or may be formed by processing a lead sheet or a lead alloy sheet. Examples of the processing method include expansion processing or punching processing. It is preferable to use a lattice-shaped current collector as the negative electrode current collector because it is easy to carry the negative electrode material.

[0079] The lead alloy used for the negative electrode current collector may be any of Pb-Sb-based alloys, Pb-Ca-based alloys, and Pb-Ca-Sn-based alloys. These lead or lead alloys may further contain at least one selected from the group consisting of Ba, Ag, Al, Bi, As, Se, Cu, etc. as additive elements. The negative electrode current collector may be provided with a surface layer. The composition of the surface layer and the inner layer of the negative electrode current collector may be different. The surface layer may be formed on a part of the negative electrode current collector. The surface layer may be formed on the ear part of the negative electrode current collector. The surface layer of the ear part may contain Sn or an Sn alloy.

[0080] The negative electrode material contains, as an essential component, a negative electrode active material (specifically, lead or lead sulfate) that exhibits capacitance through an oxidation-reduction reaction, and may contain additives such as an organic anti-shrinkage agent, a carbonaceous material, barium sulfate, and fibers (such as resin fibers). The additives are not limited to these. Note that the negative electrode active material in the charged state is spongy lead, but an unformed negative electrode plate is usually produced using lead powder. The lead powder preferably contains at least lead monoxide. The lead powder may further contain metallic lead.

[0081] The organic anti-shrinkage agent is an organic compound among the compounds having a function of suppressing the shrinkage of lead, which is the negative electrode active material, when the charge and discharge of the lead storage battery are repeated. The organic anti-shrinkage agent is generally classified into a lignin compound and a synthetic organic anti-shrinkage agent. The synthetic organic anti-shrinkage agent can also be said to be an organic anti-shrinkage agent other than the lignin compound. Examples of the organic anti-shrinkage agent contained in the negative electrode material include a lignin compound and a synthetic organic anti-shrinkage agent. The negative electrode material may contain one kind of organic anti-shrinkage agent or two or more kinds.

[0082] Examples of the lignin compound include lignin and lignin derivatives. Examples of the lignin derivative include lignin sulfonic acid or its salts (such as alkali metal salts (such as sodium salts)).

[0083] The synthetic organic shrinkage-proof agent is an organic polymer containing sulfur element. Examples of the synthetic organic shrinkage-proof agent include condensates of compounds having a sulfur-containing group and an aromatic ring with aldehyde compounds (such as aldehydes or their condensates (e.g., formaldehyde)). However, the synthetic organic shrinkage-proof agent is not limited thereto. Among the sulfur-containing groups, a sulfonic acid group or a sulfonyl group in a stable form is preferred. The sulfonic acid group may exist in an acid form or in a salt form such as a Na salt.

[0084] The content of the organic shrinkage-proof agent contained in the negative electrode material is, for example, 0.01% by mass or more, and may be 0.05% by mass or more. The content of the organic shrinkage-proof agent is, for example, 1.0% by mass or less, and may be 0.5% by mass or less. Here, the content of the organic shrinkage-proof agent contained in the negative electrode material is the content in the negative electrode material collected by the method described below from a fully charged lead storage battery in a preformed state. These lower limit values and upper limit values can be arbitrarily combined.

[0085] As the carbonaceous material contained in the negative electrode material, carbon black, graphite, hard carbon, soft carbon, etc. can be used. Examples of carbon black include acetylene black, furnace black, lamp black, etc. Furnace black includes ketjen black (trade name). Graphite may be any carbonaceous material containing a graphite-type crystal structure, and may be either artificial graphite or natural graphite. The negative electrode material may contain one kind of carbonaceous material or two or more kinds of carbonaceous materials.

[0086] The content of the carbonaceous material in the negative electrode material is, for example, 0.05% by mass or more, and may be 0.10% by mass or more. The content of the carbonaceous material is, for example, 5% by mass or less, and may be 3% by mass or less. These lower limit values and upper limit values can be arbitrarily combined.

[0087] (Barium sulfate) The content of barium sulfate in the negative electrode material is, for example, 0.05% by mass or more, and may be 0.10% by mass or more. The content of barium sulfate in the negative electrode material is, for example, 3% by mass or less, and may be 2% by mass or less. These lower limit values and upper limit values can be arbitrarily combined.

[0088] The negative electrode plate can be formed by applying or filling a negative electrode paste onto a negative electrode current collector, aging and drying to produce an unformed negative electrode plate, and then subjecting the unformed negative electrode plate to formation. The negative electrode paste is prepared, for example, by adding water and sulfuric acid (or an aqueous sulfuric acid solution) to lead powder and at least one selected from the group consisting of an organic shrinkage inhibitor, a carbonaceous material, barium sulfate, and other additives as required and kneading them. When aging, it is preferable to age the unformed negative electrode plate at a temperature higher than room temperature and high humidity.

[0089] Formation can be carried out by charging a group of electrode plates including an unformed negative electrode plate in a state where the group of electrode plates is immersed in an electrolytic solution containing sulfuric acid in the battery case of a lead storage battery. However, the formation may be carried out before the assembly of the lead storage battery or the group of electrode plates. Spongy lead is generated by the formation.

[0090] (Analysis of the Constituent Components of the Negative Electrode Material) The analysis method of the constituent components of the negative electrode material will be described below. Prior to measurement or analysis, a fully charged lead storage battery is disassembled to obtain a negative electrode plate to be analyzed. The obtained negative electrode plate is washed with water to remove sulfuric acid from the negative electrode plate. The water washing is carried out until it is confirmed that the color of the pH test paper does not change when the pH test paper is pressed against the surface of the washed negative electrode plate. However, the time for carrying out the water washing is within 2 hours. The washed negative electrode plate is dried at 60 ± 5°C for about 6 hours in a reduced-pressure environment. When an adhesive member is included in the negative electrode plate after drying, the adhesive member is removed by peeling. Next, a sample (hereinafter referred to as sample B) is obtained by separating the negative electrode material from the negative electrode plate. Sample B is pulverized as required and subjected to analysis.

[0091] (1) Analysis of the Organic Shrinkage Inhibitor (1-1) Qualitative Analysis of the Organic Anti-Shrinkage Agent in the Negative Electrode Material The pulverized sample B is immersed in a 1 mol / L aqueous sodium hydroxide solution to extract the organic anti-shrinkage agent. Next, the insoluble components are removed by filtration from the extract, and after desalting the obtained solution, it is concentrated and dried. Desalting is performed using a desalting column, by passing the solution through an ion exchange membrane, or by placing the solution in a dialysis tube and immersing it in distilled water. By drying this, a powder sample of the organic anti-shrinkage agent (hereinafter referred to as sample C) is obtained.

[0092] Combining the infrared absorption spectrum measured using the thus-obtained sample C of the organic anti-shrinkage agent, the ultraviolet-visible absorption spectrum measured with an ultraviolet-visible spectrophotometer after diluting sample C with distilled water or the like, the NMR spectrum of the solution obtained by dissolving sample C in a predetermined solvent such as heavy water, or the information obtained from thermal decomposition GC-MS or the like that can obtain information on the individual compounds constituting the substance, the type of the organic anti-shrinkage agent is specified.

[0093] (1-2) Quantification of the Content of the Organic Anti-Shrinkage Agent in the Negative Electrode Material In the same manner as in (1-1) above, a solution is obtained after removing the insoluble components by filtration from the extract containing the organic anti-shrinkage agent. For the obtained solution, the ultraviolet-visible absorption spectrum is measured. Using the intensity of the peak characteristic of the organic anti-shrinkage agent and the calibration curve prepared in advance, the content of the organic anti-shrinkage agent in the negative electrode material is determined.

[0094] When obtaining a lead storage battery with an unknown content of the organic anti-shrinkage agent and measuring the content of the organic anti-shrinkage agent, since the exact structure of the organic anti-shrinkage agent cannot be specified, the same organic anti-shrinkage agent may not be used for the calibration curve. In this case, by preparing a calibration curve using an organic polymer that is separately available and has a similar shape in the ultraviolet-visible absorption spectrum, infrared absorption spectrum, and NMR spectrum, etc., to the organic anti-shrinkage agent extracted from the negative electrode of the battery, the content of the organic anti-shrinkage agent is measured using the ultraviolet-visible absorption spectrum.

[0095] (2) Quantification of the Carbonaceous Material and Barium Sulfate To 10 g of the pulverized sample B, add 50 mL of nitric acid with a concentration of 20% by mass, heat for about 20 minutes, and dissolve the lead component as lead ions. Filter the obtained solution to separate solid components such as carbonaceous materials and barium sulfate.

[0096] After dispersing the obtained solid components in water to form a dispersion, remove components other than carbonaceous materials and barium sulfate (e.g., reinforcing materials) from the dispersion using a sieve. Next, perform suction filtration on the dispersion using a membrane filter whose mass has been previously measured, and dry the membrane filter together with the filtered sample in a dryer at 110 °C ± 5 °C. The filtered sample is a mixed sample of carbonaceous materials and barium sulfate. Subtract the mass of the membrane filter from the total mass of the dried mixed sample (hereinafter referred to as sample C) and the membrane filter to measure the mass (M m ) of sample C. Thereafter, put sample C together with the membrane filter into a crucible and incinerate it at 1300 °C or higher. The remaining residue is barium oxide. Convert the mass of barium oxide to the mass of barium sulfate to obtain the mass (M B ) of barium sulfate. Subtract the mass M m from the mass M B to calculate the mass of the carbonaceous material.

[0097] (Separator) A separator can be arranged between the negative electrode plate and the positive electrode plate. As the separator, at least one selected from non-woven fabrics and microporous membranes is used.

[0098] A non-woven fabric is a mat formed by tangling fibers without weaving and mainly consists of fibers. For example, in a non-woven fabric, 60% by mass or more of the non-woven fabric is formed of fibers. As the fibers, glass fibers, polymer fibers (such as polyolefin fibers, acrylic fibers, polyester fibers (such as polyethylene terephthalate fibers)), pulp fibers, etc. can be used. Among them, glass fibers are preferred. The non-woven fabric may contain components other than fibers (e.g., acid-resistant inorganic powders, polymers as binders), etc.

[0099] On the one hand, the microporous membrane is a porous sheet mainly composed of components other than the fiber component. For example, it can be obtained by extruding a composition containing a pore-forming agent into a sheet shape and then removing the pore-forming agent to form pores. The microporous membrane is preferably composed of a material having acid resistance, and a microporous membrane mainly composed of a polymer component is preferred. As the polymer component, polyolefin (such as polyethylene, polypropylene, etc.) is preferred. Examples of the pore-forming agent include at least one selected from the group consisting of polymer powder and oil.

[0100] The separator may be composed of, for example, only a non-woven fabric or only a microporous membrane. Further, the separator may be, if necessary, a laminate of a non-woven fabric and a microporous membrane, a bonded material of different or the same kind of materials, or a material in which unevenness of different or the same kind of materials is engaged.

[0101] The separator may be in the form of a sheet or may be formed into a bag shape. One sheet-shaped separator may be disposed so as to sandwich between the positive electrode plate and the negative electrode plate. Also, one sheet-shaped separator in a bent state may be disposed so as to sandwich the electrode plates. In this case, the positive electrode plate sandwiched by the bent sheet-shaped separator and the negative electrode plate sandwiched by the bent sheet-shaped separator may be overlapped, or one of the positive electrode plate and the negative electrode plate may be sandwiched by the bent sheet-shaped separator and overlapped with the other electrode plate. Further, the sheet-shaped separator may be bent into a bellows shape, and the positive electrode plate and the negative electrode plate may be sandwiched between the bellows-shaped separators such that the separator is interposed therebetween. When using a separator bent into a bellows shape, the separator may be disposed such that the bent portion is along the horizontal direction of the lead storage battery (for example, such that the bent portion is parallel to the horizontal direction), or may be disposed along the vertical direction (for example, such that the bent portion is parallel to the vertical direction). In the separator bent into a bellows shape, concave portions are formed alternately on both main surface sides of the separator. Since lugs are usually formed on the upper portions of the positive electrode plate and the negative electrode plate, when the separator is disposed such that the bent portion is along the horizontal direction of the lead storage battery, the positive electrode plate and the negative electrode plate are disposed only in the concave portion on one main surface side of the separator (that is, a double separator is interposed between the adjacent positive electrode plate and the negative electrode plate). When the separator is disposed such that the bent portion is along the vertical direction of the lead storage battery, the positive electrode plate can be accommodated in the concave portion on one main surface side, and the negative electrode plate can be accommodated in the concave portion on the other main surface side (that is, a single separator can be interposed between the adjacent positive electrode plate and the negative electrode plate). When using a bag-shaped separator, the bag-shaped separator may accommodate the positive electrode plate or may accommodate the negative electrode plate.

[0102] (Electrolyte solution) The electrolyte solution is an aqueous solution containing sulfuric acid and may be gelled as required. The electrolyte solution may contain the above polymer compound.

[0103] The electrolytic solution may contain cations (e.g., metal cations) and / or anions (e.g., anions other than sulfate anions such as phosphate ions) as required. Examples of the metal cations include at least one selected from the group consisting of Na ions, Li ions, Mg ions, and Al ions.

[0104] The specific gravity of the electrolytic solution in a fully charged lead storage battery at 20°C is, for example, 1.20 or more, and may be 1.25 or more. The specific gravity of the electrolytic solution at 20°C is 1.35 or less, and may be 1.32 or less. These lower limit values and upper limit values can be arbitrarily combined.

[0105] (Others) The lead storage battery can be obtained by a manufacturing method including a step of housing a plate group and an electrolytic solution in a battery case. The plate group is assembled by laminating a positive electrode plate, a negative electrode plate, and a separator so that the separator is interposed between the positive electrode plate and the negative electrode plate prior to housing in the battery case. The positive electrode plate, the negative electrode plate, the electrolytic solution, and the separator are each prepared prior to the assembly of the plate group. The manufacturing method of the lead storage battery may include a step of forming at least one of the positive electrode plate and the negative electrode plate as required after the step of housing the plate group and the electrolytic solution in the battery case. Usually, one plate group is housed in one battery case. As required, two or more plate groups may be housed in one battery case. The lead storage battery may include one battery case housing the plate group and the electrolytic solution, or may include two or more. When including two or more battery cases housing the plate group and the electrolytic solution, each plate group is usually connected in series.

[0106] Each electrode plate in the electrode plate group may be one or two or more. When the electrode plate group includes two or more positive electrode plates, for at least one positive electrode plate, if the density of the positive electrode material is within the above range and at least one of the conditions (a) and (b) above is satisfied, the generation of the resistance component for this positive electrode plate is reduced, and according to the number of such positive electrode plates, the effect of reducing the occurrence rate of voltage rise in the high-temperature deep discharge cycle in the lead storage battery can be obtained. From the viewpoint of further reducing the occurrence rate of voltage rise in the high-temperature deep discharge cycle, it is preferable that 50% or more (more preferably 80% or more or 90% or more) of the number of positive electrode plates included in the electrode plate group are positive electrode plates satisfying the above conditions. Among the positive electrode plates included in the electrode plate group, the ratio of the positive electrode plates whose density of the positive electrode material is within the above range and which satisfy the above conditions is 100% or less. It is particularly preferable that all of the positive electrode plates included in the electrode plate group have a density of the positive electrode material within the above range and satisfy the above conditions.

[0107] When the lead storage battery has two or more electrode plate groups, at least a part of the electrode plate groups may be provided with positive electrode plates whose density of the positive electrode material is within the above range and which satisfy the above conditions. From the viewpoint of further reducing the occurrence rate of voltage rise in the high-temperature deep discharge cycle, it is preferable that 50% or more (more preferably 80% or more or 90% or more) of the number of electrode plate groups included in the lead storage battery are electrode plate groups including positive electrode plates whose density of the positive electrode material is within the above range and which satisfy the above conditions. Among the electrode plate groups included in the lead storage battery, the ratio of the electrode plate groups including positive electrode plates whose density of the positive electrode material is within the above range and which satisfy the above conditions is 100% or less. It is preferable that all of the electrode plate groups included in the lead storage battery are provided with positive electrode plates whose density of the positive electrode material is within the above range and which satisfy the above conditions.

[0108] FIG. 1 is a perspective view schematically showing an example of a lead storage battery according to an embodiment of the present invention with the lid removed. FIG. 2A is a front view of the lead storage battery of FIG. 1, and FIG. 2B is a schematic cross-sectional view when the cross-section taken along line IIB-IIB of FIG. 2A is viewed from the arrow direction. The lead-acid battery 1 includes a battery case 10 that houses a plate group 11 and an electrolyte 12. The plate group 11 is configured by laminating a plurality of negative plates 2 and clad-type positive plates 3 via separators 4. Here, a state where a sheet-like separator 4 is sandwiched between the negative plate 2 and the clad-type positive plate 3 is shown, but the form of the separator is not particularly limited.

[0109] On each upper part of the plurality of negative plates 2, there are provided current collecting ears (not shown) that protrude upward. On each upper part of the plurality of clad-type positive plates 3, there are also provided current collecting ears (not shown) that protrude upward. Then, the ears of the negative plates 2 are connected and integrated by a negative strap 5a. Similarly, the ears of the clad-type positive plates 3 are connected and integrated by a positive strap 5b. The lower end of a negative terminal post 6a is fixed to the upper part of the negative strap 5a, and the lower end of a positive terminal post 6b is fixed to the upper part of the positive strap 5b.

[0110] The clad-type positive plate for a lead-acid battery and the lead-acid battery according to one aspect of the present invention are summarized below.

[0111] (1) A clad-type positive plate for a lead-acid battery, The positive plate includes a plurality of porous tubes, a grid housed in the tubes, a positive electrode material filled in the tubes, and a current collecting part that connects one ends in the length direction of the plurality of grids arranged in a row. The positive electrode material contains organic fibers. The density of the positive electrode material is 3 3.75 g / cm or less. The number of the organic fibers per unit volume (cm 3 ) of the positive electrode material is 400 or more and 15,000 or less. A clad-type positive plate for a lead-acid battery.

[0112] (2) In the above (1), the number of the organic fibers per unit volume of the positive electrode material may be 800 or more. (3) In the above (1) or (2), the number of the organic fibers per unit volume of the positive electrode material may be 10,000 or less, 7,500 or less, or 7,200 or less.

[0113] (4) In any one of the above (1) to (3), the ratio of the organic fibers in the positive electrode material may be 0.013% by volume or more and 0.5% by volume or less.

[0114] (5) A clad type positive electrode plate for a lead storage battery, wherein the positive electrode plate includes a plurality of porous tubes, a core metal accommodated in the tubes, a positive electrode material filled in the tubes, and a current collecting portion that connects one end portion in the longitudinal direction of the plurality of core metals arranged in a row. The positive electrode material contains organic fibers, the density of the positive electrode material is 3.75 g / cm 3 or less, and the ratio of the organic fibers in the positive electrode material is 0.013% by volume or more and 0.5% by volume or less. A clad type positive electrode plate for a lead storage battery.

[0115] (6) In any one of the above (1) to (5), the ratio of the organic fibers in the positive electrode material may be 0.026% by volume or more.

[0116] (7) In any one of the above (1) to (6), the ratio of the organic fibers in the positive electrode material may be 0.32% by volume or less, 0.25% by volume or less, or 0.23% by volume or less.

[0117] (8) In any one of the above (1) to (7), the organic fibers may include fibers (first fibers) having a specific gravity of 1.2 or more.

[0118] (9) In the above (8), the specific gravity of the first fibers may be 1.25 or more or 1.26 or more.

[0119] (10) In the above (8) or (9), the specific gravity of the first fiber may be 1.7 or less, 1.6 or less, or 1.5 or less.

[0120] (11) In any one of the above (8) to (10), the ratio of the first fiber to the total organic fiber contained in the positive electrode material may be 60% by volume or more, 75% by volume or more, or 90% by volume or more.

[0121] (12) In the above (11), the ratio of the first fiber may be 100% by volume or less.

[0122] (13) In any one of the above (8) to (10), the positive electrode material may contain only the first fiber as the organic fiber.

[0123] (14) In any one of the above (1) to (13), the organic fiber may contain an oxygen element.

[0124] (15) In the above (14), the content of the oxygen element in the organic fiber may be 10000 μmol / g or more, 15000 μmol / g or more, 17000 μmol / g or more, 17400 μmol / g or more, 19000 μmol / g or more, 20000 μmol / g or more, or 20800 μmol / g or more.

[0125] (16) In the above (14) or (15), the content of the oxygen element in the organic fiber may be 50000 μmol / g or less, 40000 μmol / g or less, or 35000 μmol / g or less.

[0126] (17) In any one of the above (1) to (16), the average fiber diameter of the organic fiber may be 1 μm or more, 5 μm or more, or 10 μm or more.

[0127] (18) In any one of the above (1) to (17), the average fiber diameter of the organic fiber may be 50 μm or less, 30 μm or less, or 20 μm or less.

[0128] (19) In any one of the above (1) to (18), the average fiber length of the organic fiber may be 0.1 mm or more, 0.5 mm or more, 1 mm or more, 1.5 mm or more, or 2 mm or more.

[0129] (20) In any one of the above (1) to (19), the average fiber length of the organic fiber may be 10 mm or less, or 6 mm or less.

[0130] (21) In any one of the above (1) to (20), the organic fiber may contain at least one selected from the group consisting of polyester fiber, acetalized polyvinyl alcohol fiber, polyurethane fiber, and cellulose fiber.

[0131] (22) In any one of the above (1) to (21), the density of the positive electrode material may be 3.7 g / cm 3 or less.

[0132] (23) In any one of the above (1) to (22), the density of the positive electrode material may be 3.3 g / cm 3 or more.

[0133] (24) A lead storage battery, The lead storage battery includes at least one electrode plate group and an electrolyte, The electrode plate group includes at least one clad type positive electrode plate according to any one of the above (1) to (23), at least one negative electrode plate, and a separator interposed between the clad type positive electrode plate and the negative electrode plate. A lead storage battery.

[0134] (25) In the above (24), the negative electrode plate may contain a negative electrode material.

[0135] (26) In the above (25), the negative electrode material may contain an organic shrinkage inhibitor.

[0136] (27) In the above (26), the content of the organic anti-shrinkage agent in the negative electrode material may be 0.01% by mass or more, or 0.05% by mass or more.

[0137] (28) In the above (26) or (27), the content of the organic anti-shrinkage agent in the negative electrode material may be 1.0% by mass or less, or 0.5% by mass or less.

[0138] (29) In any one of the above (25) to (28), the negative electrode material may contain a carbonaceous material.

[0139] (30) In the above (29), the content of the carbonaceous material in the negative electrode material may be 0.05% by mass or more, or 0.10% by mass or more.

[0140] (31) In the above (29) or (30), the content of the carbonaceous material in the negative electrode material may be 5% by mass or less, or 3% by mass or less.

[0141] (32) In any one of the above (25) to (31), the negative electrode material may contain barium sulfate.

[0142] (33) In the above (32), the content of the barium sulfate in the negative electrode material may be 0.05% by mass or more, or 0.10% by mass or more.

[0143] (34) In the above (32) or (33), the content of the barium sulfate in the negative electrode material may be 3% by mass or less, or 2% by mass or less.

[0144] (35) In any one of the above (25) to (34), the specific gravity of the electrolyte in the fully charged lead-acid battery at 20 °C may be 1.20 or more, or 1.25 or more.

[0145] (36) In any one of the above (25) to (35), the specific gravity of the electrolyte in the fully charged lead-acid battery at 20 °C may be 1.35 or less, or 1.32 or less.

[0146] [Examples] Hereinafter, the present invention will be specifically described based on examples and comparative examples, but the present invention is not limited to the following examples.

[0147] 《Lead-acid batteries E1 to E19, R1 to R2, and C1 to C6》 (1) Fabrication of positive electrode plates The clad type positive electrode plates are fabricated according to the following procedure. First, each of the 15 grid cores with one end of the length direction integrated with the current collecting part having ears is accommodated in each of the 15 tubes. An upper resin connector is formed by covering the current collecting part and one end of the length direction of the current collecting part side of the tube with resin so that the ears are exposed. Note that the materials of the grid core and the current collecting part are Pb-Sb alloy, and the length of each grid core is 295 mm. As the tube, a porous glass fiber tube with a length of 310 mm and an outer diameter of 9.5 mm is used.

[0148] A positive electrode slurry prepared by kneading lead powder (containing 80% by mass of lead oxide and 20% by mass of metallic lead), lead red lead, the organic fiber shown in the table, water, and dilute sulfuric acid is filled from the opening at the other end of the length direction of the tube. Next, the opening at the other end of the tube is sealed with a lower connector and dried. In this way, an unformed clad type positive electrode plate is fabricated. The width of the fabricated positive electrode plate is 143 mm.

[0149] Note that the mass ratio of lead powder to lead red lead is 9:1. The addition amount of the organic fiber is adjusted so that the number of organic fibers per unit volume (cm 3 ) of the positive electrode material obtained by the above procedure or the ratio of the organic fiber in the positive electrode material becomes the value shown in the table. The filling amount of the positive electrode slurry is adjusted so that the density of the positive electrode material obtained by the above procedure becomes the value shown in the table. The average fiber diameter of the organic fiber obtained by the above procedure is 14 μm, and the average fiber length is 2 mm.

[0150] (2) Fabrication of Negative Plate Lead powder (containing 80% by mass of lead oxide and 20% by mass of metallic lead), 0.3% by mass of carbon black, 0.1% by mass of an organic anti - shrinkage agent (sodium lignin sulfonate), and 1.5% by mass of barium sulfate are mixed with water and dilute sulfuric acid to prepare a negative electrode paste. The negative electrode paste is filled into a cast grid (thickness 4.4 mm) made of an Sb - based alloy as a negative electrode current collector and dried to produce an unformed negative plate (thickness 4.5 mm). The filling amount of the negative electrode paste is adjusted so that the mass of the negative electrode active material contained in the negative electrode material of one formed negative plate is 750 ± 6 g in terms of Pb element. The length of the negative plate is made the same as the length of the tube of the positive plate, and the width of the negative plate is made the same as the width of the positive plate.

[0151] (3) Fabrication of Lead - Acid Battery Four unformed negative plates and three unformed clad - type positive plates having the same - shaped internal cores are alternately stacked with a separator interposed therebetween to form a plate group as shown in Fig. 2B. As the separator, a microporous membrane made of polypropylene having ribs on one surface is used. The separator is arranged such that the ribs are positioned on the positive plate side.

[0152] The plate group is housed in a polypropylene battery case, dilute sulfuric acid with a specific gravity of 1.280 at 20°C is poured in, and a lid is fixed to the opening of the battery case by adhesion. The battery case is held in a water bath at 30°C ± 2°C for formation. In this way, lead - acid batteries E1 - E19, C1 - C6, and R1 - R2 with a rated voltage of 2V and a rated capacity (5 - hour rate) of 165 Ah are obtained. The lead - acid batteries are almost fully charged by formation.

[0153] (4) Evaluation (a) Incidence of Voltage Rise during High - Temperature Deep - Discharge Cycles Using a fully charged and formed lead-acid battery, a high-temperature deep discharge cycle test is performed. In the high-temperature deep discharge cycle test, the lead-acid battery is maintained in a water tank at a temperature of 75°C ± 5°C and discharged at a current of 41.25 A for 3 hours, and then charged at a current of 29.7 A for 5.44 hours. This discharge and charge cycle is defined as one cycle, and 200 cycles of charge and discharge are repeated.

[0154] During the 200 cycles of charge and discharge, the ratio (%) of the cycles in which the time until the terminal voltage of the lead-acid battery reaches 2.4 V during charging is less than 3.5 hours is determined. This ratio corresponds to the occurrence rate of voltage rise during charging in the high-temperature deep discharge cycle test and serves as an index for evaluating the voltage rise in the high-temperature deep discharge cycle.

[0155] (b) Initial capacity For lead-acid batteries C1, E1, and E14 to E19, the initial capacity is measured according to the following procedure. First, a fully charged and formed lead-acid battery is maintained in a water tank at a temperature of 30°C ± 2°C and discharged at a current of 33 A until 70 V, and then charged at a current of 33 A until the charge amount reaches 135% of the discharge charge amount. Then, it is discharged again at a current of 33 A until 1.70 V, and the discharge capacity at this time is measured and taken as the initial capacity. The initial capacity is evaluated as a ratio when the initial capacity of lead-acid battery C1 is set to 100%. The results are shown in Tables 1 to 4 and Figures 3 to 9.

[0156]

Table 1

[0157] As shown in Table 1 and Figure 3, in the positive electrode material of the clad type positive electrode plate, when the density is 3.75 g / cm 3 and below, the occurrence rate of voltage rise in the high-temperature deep discharge cycle increases (comparison between C1 to C4 and C5 to C6). On the other hand, when the positive electrode material contains organic fibers, when the density is 3.75 g / cm 3The generation rate of voltage increase during high-temperature deep discharge cycles can be significantly reduced in the following cases (comparison between C1 - C4 and E1 - E4). This is presumably because the presence of organic fibers in the positive electrode material hinders the movement of ions and makes it difficult to generate resistance components. Note that when the density of the positive electrode material exceeds 3.75 g / cm 3 no difference in the generation rate of voltage increase during high-temperature deep discharge cycles is observed depending on the presence or absence of organic fibers (comparison between C5 - C6 and R1 - R2). In other words, there is no issue with voltage increase during high-temperature deep discharge cycles itself.

[0158]

Table 2

[0159] As shown in Table 2, Figure 4, and Figure 5, the effect of reducing voltage increase during high-temperature deep discharge cycles can be obtained when the number of organic fibers per unit volume (cm 3 ) of the positive electrode material is 400 or more and / or the ratio of organic fibers in the positive electrode material is 0.013% by volume or more. From the perspective of further reducing the generation rate of voltage increase during high-temperature deep discharge cycles, it is preferable that the number of organic fibers per unit volume (cm 3 ) of the positive electrode material is 800 or more and / or the ratio of organic fibers in the positive electrode material is 0.026% by volume or more.

[0160]

Table 3

[0161] As shown in Table 3 and Figure 6, when the specific gravity of the organic fiber is 1.2 or more (preferably 1.25 or more or 1.26 or more), the generation rate of voltage increase during high-temperature deep discharge cycles can be further reduced.

[0162] As shown in Table 3 and FIG. 7, when the oxygen element content of the organic fiber is 15,000 μmol / g or more (preferably 17,000 μmol / g or more or 17,400 μmol / g or more), the occurrence rate of voltage increase during high-temperature deep discharge cycles can be further reduced.

[0163] These effects are considered to be due to the fact that the dispersibility of the organic fiber in the positive electrode material is enhanced, further restricting the movement of ions.

[0164]

Table 4

[0165] As shown in Table 4 and FIG. 8, from the viewpoint of easily ensuring a higher initial capacity, the number of organic fibers per unit volume of the positive electrode material is more preferably 7,500 or less or 7,200 or less. From the same viewpoint, the ratio of the organic fiber in the positive electrode material is more preferably 0.25% by volume or less or 0.23% by volume or less (Table 4 and FIG. 9).

Industrial Applicability

[0166] The clad-type positive electrode plate according to one aspect of the present invention can be suitably used for industrial long-life lead-acid batteries or lead-acid batteries for electric vehicles (such as forklifts). Further, the clad-type positive electrode plate may be used, for example, for lead-acid batteries for vehicles such as automobiles and motorcycles. However, these applications are merely examples, and the applications of the clad-type positive electrode plate and the lead-acid battery provided with the same are not limited thereto.

Explanation of Signs

[0167] 1: Lead-acid battery 2: Negative electrode plate 3: Positive electrode plate 4: Separator 5a: Negative electrode strap 5b: Positive electrode strap 6a: Negative electrode post 6b: Positive electrode post 10: Battery case 11: Electrode plate group 12: Electrolyte

Claims

1. A clad-type positive electrode plate for a lead storage battery, wherein the positive electrode plate includes a plurality of porous tubes, a core bar accommodated in the tubes, a positive electrode material filled in the tubes, and a current collector connecting one ends in the longitudinal direction of the plurality of core bars arranged in a row. The positive electrode material contains organic fibers, The density of the positive electrode material is 3.75 g / cm 3 or less, The number of the organic fibers per unit volume (cm 3 ) of the positive electrode material is 400 or more and 15000 or less. A clad-type positive electrode plate for a lead storage battery.

2. The ratio of the organic fibers in the positive electrode material is 0.013% by volume or more and 0.5% by volume or less. The clad-type positive electrode plate for a lead storage battery according to Claim 1.

3. A clad-type positive electrode plate for a lead storage battery, wherein the positive electrode plate includes a plurality of porous tubes, a core bar accommodated in the tubes, a positive electrode material filled in the tubes, and a current collector connecting one ends in the longitudinal direction of the plurality of core bars arranged in a row. The positive electrode material contains organic fibers, The density of the positive electrode material is 3.75 g / cm 3 or less, The ratio of the organic fibers in the positive electrode material is 0.013% by volume or more and 0.5% by volume or less. A clad-type positive electrode plate for a lead storage battery.

4. The organic fibers include fibers having a specific gravity of 1.2 or more. The clad-type positive electrode plate for a lead storage battery according to any one of Claims 1 to 3.

5. The organic fibers contain an oxygen element, and the content of the oxygen element in the organic fibers is 10000 μmol / g or more. The clad-type positive electrode plate for a lead storage battery according to any one of Claims 1 to 4.

6. The clad positive electrode plate for a lead storage battery according to any one of claims 1 to 5, wherein the organic fiber contains at least one selected from the group consisting of polyester fiber, acetalized polyvinyl alcohol fiber, polyurethane fiber, and cellulose fiber.

7. A lead storage battery, comprising at least one electrode plate group and an electrolyte, wherein the electrode plate group comprises at least one clad positive electrode plate according to any one of claims 1 to 6, at least one negative electrode plate, and a separator interposed between the clad positive electrode plate and the negative electrode plate.

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