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

Abstract

To provide a clad type positive electrode plate for a lead acid battery that can increase a chemical conversion degree of a positive electrode material, and a lead acid battery including the same.SOLUTION: A clad type positive electrode plate for a lead acid battery includes at least one porous tube 31, a positive electrode material 32 filling the porous tube 31, and a positive electrode current collector 33. The positive electrode current collector 33 includes at least one core grid 35, and a current collector part 34 connecting to an end part of the core grid 35. The core grid 35 is disposed in the tube 31, and is in contact with the positive electrode material 32. The core grid 35 includes a bar-like part 352 including a first end part 352a on the current collector part 34 side and a second end part 352b on an opposite side of the first end part. At the first end part 352a, a center of the bar-like part 352 is deviated from a center of the tube 31. At the first end part 352a, the shortest distance between the bar-like part 352 and the tube 31 is 2.0 mm or less.SELECTED DRAWING: Figure 3

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] In lead storage batteries, as the positive electrode plate, a paste-type positive electrode plate, a clad-type positive electrode plate, etc. are used. 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. In the clad-type positive electrode plate, the characteristics of the battery change depending on the shape of the positive electrode current collector. Therefore, various positive electrode current collectors have been proposed.

[0003] Patent Document 1 (Japanese Patent Laid-Open No. 50-161640) discloses "a method for manufacturing a clad-type grid body for a lead storage battery, which comprises a step of forming a core metal having blades by pressing a drawn rod-shaped body of lead or a lead alloy at appropriate intervals, and a step of attaching and fixing this core metal to a mold and injecting a molten lead or lead alloy to form a frame body."

[0004] Patent Document 2 (Japanese Patent Laid-Open No. 56-167272) discloses "a fiber clad-type substrate in which a plurality of vertical rods are suspended at predetermined intervals on a horizontal rod, and the horizontal rod of a lead alloy material having a comb-tooth shape is bent and polymerized, and the vertical rod is used as a core metal."

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the conventional clad-type positive electrode plate, there were cases where the degree of formation of the positive electrode material could not be sufficiently increased. In such a situation, one of the objectives of the present invention is to provide a clad-type positive electrode plate for a lead storage battery that can increase the degree of formation of the positive electrode material, and a lead storage battery including the same.

Means for Solving the Problems

[0007] One aspect of the present invention relates to a clad-type positive electrode plate for a lead storage battery. The positive electrode plate includes at least one porous tube, a positive electrode material filled in the porous tube, and a positive electrode current collector. The positive electrode current collector includes at least one core bar and a current collecting portion connected to an end of the core bar. The core bar is disposed in the tube and is in contact with the positive electrode material. The core bar includes a rod-shaped portion having a first end on the current collecting portion side and a second end opposite to the first end. At the first end, the center of the rod-shaped portion is displaced from the center of the tube, and at the first end, the shortest distance between the rod-shaped portion and the tube is 2.0 mm or less.

[0008] Another aspect of the present invention relates to a lead storage battery. The lead storage battery includes the clad-type positive electrode plate for a lead storage battery of the present invention.

Advantages of the Invention

[0009] According to the present invention, a clad-type positive electrode plate capable of increasing the degree of formation of the positive electrode material, and a lead storage battery including the same can be obtained.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6A

Figure 6B

Figure 7

Figure 8

MODE FOR CARRYING OUT THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with examples, but the present invention is not limited to the examples described below. In the following description, specific numerical values and materials may be exemplified, but other numerical values and materials may be applied as long as the effects of the present invention can be obtained. In this specification, the range described as "numerical value A to numerical value B" includes numerical value A and numerical value B and can be read as "A or more and B or less".

[0012] (Clad type positive electrode plate) The clad type positive electrode plate of the present embodiment is used for a lead storage battery. The clad type positive electrode plate includes at least one porous tube, a positive electrode material filled in the porous tube, and a positive electrode current collector. The porous tube may be hereinafter referred to as "tube (T)". The positive electrode current collector includes at least one core bar and a current collecting portion connected to the end of the core bar. The core bar is disposed in the tube (T) and is in contact with the positive electrode material. The core bar includes a rod-shaped portion having a first end on the current collecting portion side and a second end opposite to the first end. At the first end, the center of the rod-shaped portion is deviated from the center of the tube (T). At the first end, the shortest distance Lmin between the rod-shaped portion and the tube (T) is 2.0 mm or less.

[0013] The direction in which the tube (T) extends may hereinafter be referred to as "direction DL" in some cases. From another perspective, direction DL is a direction parallel to the central axis of the tube (T), or the longitudinal direction of the tube (T).

[0014] In the following description, the center of the rod-shaped part at the first end means the position of the central axis of the rod-shaped part at the first end. Similarly, the center of the tube (T) at the first end means the position of the central axis of the tube (T) at the first end. Similarly, for the center of other components at the first end and the center of the components at the second end, it also means the position of the central axis of the component in that part.

[0015] When a component (such as a rod-shaped part or a tube (T)) is cylindrical or hollow cylindrical, the central axis of the component is the center of the circular cross-section (cross-section perpendicular to direction DL) of the component. In addition, when the component is neither cylindrical nor hollow cylindrical, the position of the centroid of the cross-section (cross-section perpendicular to direction DL) of the component can be taken as the position of the central axis of the component. That is, in this case, the line connecting the centroids along direction DL can be regarded as the central axis.

[0016] The rod-shaped part means a region where its diameter is generally constant. For example, when the diameter of the rod-shaped part changes depending on the position in the length direction, a part where the maximum value and the minimum value of the changing diameters are within the range of ±15% (preferably ±5%) of their average value may also be acceptable. The diameter of the rod-shaped part is the diameter of the cross-section perpendicular to the direction in which the rod-shaped part extends (the direction of the central axis). When the shape of the cross-section is not a circle, the diameter of the circle (equivalent circle) having the same area as the area of the cross-section is taken as the diameter of the rod-shaped part.

[0017] The rod-shaped part typically has a cylindrical shape. There is no particular limitation on the diameter (for example, the diameter) of the rod-shaped part, and it may be in the range of 0.25 to 0.40 times the inner diameter of the tube (for example, in the range of 0.30 to 0.38 times). The rod-shaped part may have a shape other than cylindrical (for example, prismatic).

[0018] In a general positive electrode current collector of a clad type positive electrode plate, the position of the core metal on the current collecting portion side is fixed, but the positions of the other core metals are not fixed. Therefore, when such a general positive electrode current collector is used, the position of the core metal is more likely to be eccentric as the distance from the current collecting portion increases (that is, it is more likely to deviate from the central axis of the porous tube). A schematic cross-sectional view of an example of such a conventional clad type positive electrode plate is shown in FIG. 8.

[0019] The positive electrode plate shown in FIG. 8 includes a tube 1031, a positive electrode active material 1032, and a positive electrode current collector 1033. The positive electrode current collector 1033 includes a current collecting portion 1034 and a core metal 1035. The positive electrode active material 1032 and the core metal 1035 are disposed inside the tube 1031. The tip side of the core metal 1035 is not fixed. Therefore, when a general positive electrode current collector 1033 is used, the core metal 1035 on the current collecting portion 1034 side is located near the center of the tube 1031, but the core metal 1035 at a position away from the current collecting portion 1034 may be eccentric to the extent that it contacts the inner peripheral surface of the tube 1031. In FIG. 8, a portion away from the tube 1031 may be referred to as a separated portion 1035a, and a portion of the core metal 1035 close to the tube 1031 may be referred to as a proximity portion 1035b. In an example of FIG. 8, the core metal 1035 at a position close to the current collecting portion 1034 is the separated portion 1035a, and the core metal 1035 at a position away from the current collecting portion 1034 is the proximity portion 1035b.

[0020] The positive electrode active material contains a large amount of lead monoxide PbO with low electrical conductivity (hereinafter sometimes referred to as "unformed active material"). Further, ions involved in the forming reaction move through the pores of the positive electrode active material. Therefore, in the positive electrode active material around the proximity portion 1035b, the resistance of the unformed active material and the resistance when ions pass through the pores are relatively small. Therefore, around the proximity portion 1035b, more forming current flows in the initial stage of forming, and as a result, the amount of PbO2 generated by the forming reaction increases. PbO2 has a higher electrical conductivity than the unformed active material. Therefore, in the positive electrode active material around the proximity portion 1035b, due to the originally small resistance and the electrical conductivity that improves as the forming progresses, the forming reaction proceeds rapidly.

[0021] Sulfation also proceeds simultaneously in the negative electrode plate facing the positive electrode plate. Therefore, in the negative electrode plate as well, sulfation starts to proceed first from the negative electrode active material portion facing the proximity portion 1035b of the core metal 1035. When the sulfation of the active material in the positive electrode active material around the proximity portion 1035b and the negative electrode active material portion facing the proximity portion 1035b is almost completed (for example, in the latter stage of sulfation), most of the sulfation current flows into the separation portion 1035a. However, in addition to the current density increasing due to the concentration of the sulfation current in the separation portion 1035a, since the resistance of the positive electrode active material around the separation portion 1035a is originally large, in the separation portion 1035a, the increase rate of PbO2 (i.e., the sulfation efficiency) with respect to the applied amount of electricity is significantly lower than that in the proximity portion 1035b.

[0022] Due to the mechanism as described above, in the conventional clad-type positive electrode plate, there was a large difference between the degree of sulfation of the positive electrode active material near the current collector portion and the degree of sulfation of the positive electrode active material in the portion away from the current collector portion. As a result, the degree of sulfation of the positive electrode active material in the entire positive electrode plate tended to decrease.

[0023] The variation in the degree of sulfation of the positive electrode active material is relatively small when the sulfation current applied during sulfation is small. However, when the sulfation current is large (for example, when high-speed sulfation is performed), in the initial stage of sulfation, the difference between the sulfation current density in the proximity portion 1035b and the sulfation current density in the separation portion 1035a becomes extremely large. Furthermore, in the latter stage of sulfation when the sulfation in the proximity portion 1035b is almost completed, the sulfation current concentrates in the separation portion 1035a with high resistance, and the sulfation efficiency decreases. Therefore, when the sulfation current is large, the variation in the degree of sulfation of the positive electrode active material becomes significant.

[0024] The core metal of the positive electrode current collector used in the present embodiment includes a rod-shaped portion having a first end portion on the current collector portion side and a second end portion on the side opposite to the first end portion. And at the first end portion, the center (position of the central axis) of the rod-shaped portion is displaced from the center (position of the central axis) of the tube (T). According to this configuration, the deviation in the degree of sulfation in the entire positive electrode can be reduced, and the degree of sulfation of the entire positive electrode can be increased.

[0025] The current collector core is a part of the positive electrode current collector that has a surface in contact with the positive electrode material. The current collecting part is not in contact with the positive electrode material.

[0026] There is no limitation on the length L0 of the current collector core in the direction DL in which the tube (T) extends, and it may be in the range of 150 mm to 450 mm (for example, in the range of 200 mm to 400 mm). The length of the rod-shaped part in the direction DL may be in the range of 0.95 to 1.0 times the length of the current collector core (for example, in the range of 0.97 to 1.0 times).

[0027] At the first end, the shortest distance Lmin between the rod-shaped part and the tube (T) (the inner peripheral surface of the tube (T)) is 2.0 mm or less, and may be 1.5 mm or less, 1.0 mm or less, or 0.5 mm or less. For example, the shortest distance Lmin may be 0 mm, that is, the rod-shaped part and the tube (T) may be in contact at the first end. From the viewpoint of increasing the degree of formation of the positive electrode material, it is preferable that the shortest distance Lmin is small.

[0028] In the positive electrode plate of the present embodiment, the center of the second end of the rod-shaped part (the position of the central axis of the rod-shaped part at the second end) may be located in a direction opposite to the center of the first end (the position of the central axis of the rod-shaped part at the first end) with the central axis of the tube (T) interposed therebetween. According to this configuration, the unevenness in the degree of formation in the entire positive electrode material can be particularly reduced, and the degree of formation of the entire positive electrode material can be particularly increased. Note that all parts of the rod-shaped part may be in contact with the inner peripheral surface of the tube (T). Also in this case, the unevenness in the degree of formation in the entire positive electrode material can be reduced, and the degree of formation of the entire positive electrode material can be increased.

[0029] At the first end, the distance G1 (mm) between the center of the rod-shaped part and the center of the tube (T), the inner diameter Dt1 (mm) of the tube (T), and the diameter Db1 (mm) of the rod-shaped part may satisfy (0.5Dt1 - 0.5Db1 - 2.0) ≤ G1, or may satisfy (0.5Dt1 - 0.5Db1 - 2.0) ≤ G1 ≤ (0.5Dt1 - 0.5Db1). When the rod-shaped part is cylindrical, the diameter Db1 is the diameter Db1 of the rod-shaped part. When the rod-shaped part is cylindrical, the distance G1 (mm) at the first end is at most (0.5Dt1 - 0.5Db1) mm. The distance G1 may be in the range of 0.3 to 1 times the maximum value. The distance G1 may be 1.0 mm or more, or 2.0 mm or more.

[0030] In the positive electrode plate of the present embodiment, the second end may be in contact with the inner peripheral surface of the tube (T). For example, both the first end and the second end may be in contact with the inner peripheral surface of the tube. According to these configurations, the variation in the degree of formation in the entire positive electrode material can be particularly reduced.

[0031] Normally, the positive electrode plate of the present embodiment includes a plurality of tubes (T) arranged in a row, and the positive electrode current collector includes a plurality of core metals whose respective ends are connected by current collecting parts. The number of tubes (T) is the same as the number of core metals. There is no limitation on the number of tubes (T) and core metals, and they may each be in the range of 1 to 30 (for example, in the range of 13 to 20).

[0032] (Lead-acid battery) The lead-acid battery of the present embodiment includes the clad-type positive electrode plate for a lead-acid battery of the present embodiment. Thereby, it becomes possible to suppress the self-discharge of the battery at the initial stage, and it also becomes possible to improve the initial discharge capacity. There is no particular limitation on the configuration other than the positive electrode plate, and a known configuration used for a clad-type lead-acid battery may be applied.

[0033] Hereinafter, examples of the main components of the clad-type positive electrode plate and the lead-acid battery including the same according to the present embodiment will be described. However, the components of the present invention are not limited to the following examples. Hereinafter, an example in which the positive electrode plate includes a plurality of porous tubes (T) will be described.

[0034] (Clad-type positive electrode plate) The clad-type positive electrode plate includes a plurality of porous tubes (T), a positive electrode material filled in the tubes (T), and a positive electrode current collector. The positive electrode current collector has the above-described characteristics. The clad-type positive electrode plate usually includes a connecting base that connects a plurality of tubes (T).

[0035] (Positive electrode current collector) The positive electrode current collector is made of, for example, a lead alloy. As the lead alloy, a Pb-Sb-based alloy is preferably used. The Pb-Sb-based alloy may contain at least one element selected from the group consisting of arsenic, selenium, bismuth, and tin, etc., as required.

[0036] The core metal of the positive electrode current collector may include a tapered portion on the current collecting portion side and a rod-shaped portion extending from the tapered portion. The tapered portion has a smaller diameter from the current collecting portion side toward the rod-shaped portion side and may have a frustum of a cone shape (including a shape similar to the frustum of a cone shape). The core metal may include a columnar portion disposed between the tapered portion and the current collecting portion. The columnar portion usually has a cylindrical shape (including a shape similar to a cylindrical shape). In the vicinity of the current collecting portion, the tapered portion, or the tapered portion and the columnar portion are disposed so as to close the opening on the current collecting portion side of the tube (T). A resin (for example, polyolefin (such as polyethylene, polypropylene, etc.)) may be filled in the gap between a part of the tapered portion and the inner peripheral surface of the tube, or the gap between a part of the tapered portion and the columnar portion and the inner peripheral surface of the tube.

[0037] When the core metal includes a tapered portion on the current collecting portion side (a tapered portion that is not a rod-shaped portion) and a rod-shaped portion connected thereto, the first end of the rod-shaped portion is the boundary between the tapered portion and the rod-shaped portion. Therefore, the shortest distance Lmin between the rod-shaped portion and the tube (T) at the first end is the shortest distance between the surface of the rod-shaped portion at the boundary between the tapered portion and the rod-shaped portion and the tube (T).

[0038] There is no particular limitation on the manufacturing method of the positive electrode current collector, and it may be manufactured by a known method. For example, the positive electrode current collector may be manufactured by a casting method (including a die-casting method).

[0039] (Porous tube) The porous tube (tube (T)) houses a core metal and a positive electrode material inside. As a whole, the tube (T) has a hollow cylindrical shape. The tube (T) is porous and allows the electrolyte to pass through. The tube (T) is usually a tubular fiber aggregate. The tubular fiber aggregate may be an aggregate formed by knitting fibers into a tubular shape. The tubular fiber aggregate may be a tubular non-woven fabric or a woven fabric. Examples of the fibers include inorganic fibers (such as glass fibers) and resin fibers. The tube (T) may be heat-treated as required. The tube (T) may be formed by impregnating a tubular fiber aggregate with a resin.

[0040] The length of the tube (T) may be selected according to the length of the core metal. For example, the length of the tube (T) may be somewhat longer than the length L0 of the core metal in the direction DL. The inner diameter and thickness of the tube (T) are selected according to the shape of the core metal and / or the application of the lead-acid battery, etc.

[0041] There is no particular limitation on the inner diameter of the tube (T), and it may be in the range of 9.0 mm to 10.5 mm (for example, in the range of 9.3 mm to 10.3 mm). The inner diameter of the tube (T) is the diameter in a cross-section perpendicular to the longitudinal direction of the tube (T), and is usually constant. The cross-section of the tube (T) has a circular or nearly circular shape. Therefore, the cross-sectional shape of the tube (T) can be regarded as a circle.

[0042] There is no particular limitation on the thickness of the tube (T), and it may be a thickness that functions as a tube of a clad-type positive electrode plate. The thickness of the tube (T) may be in the range of 0.1 mm to 0.8 mm (for example, in the range of 0.3 mm to 0.6 mm).

[0043] The positive electrode material contains a positive electrode active material (specifically, at least one of lead dioxide and lead sulfate) that exhibits capacitance through a redox reaction. The positive electrode material may further contain other additives as necessary.

[0044] There is no limitation to the manufacturing method of the clad type positive electrode plate, and for example, it may be manufactured by the following method. First, each of a plurality of grid cores is accommodated in a plurality of tubes (T). Next, an unformed positive electrode material (the material that becomes the positive electrode material) is filled into the tube (T) to form an unformed positive electrode plate. By forming the unformed positive electrode plate, a positive electrode plate is obtained.

[0045] When filling the unformed positive electrode material into the tube (T), it is possible to control the position of the second end by tilting the tube (T) for filling. For example, the filling may be performed by tilting the tube (T) such that the second end is positioned in the direction opposite to the direction in which the first end exists with respect to the central axis of the tube (T). By such filling, it is possible to position the center of the second end in the direction opposite to the center of the first end across the central axis of the tube (T).

[0046] The unformed positive electrode plate may be manufactured by the following procedure. First, each of a plurality of grid cores is accommodated in a tube (T). Next, one end of each of the plurality of tubes (T) and the current collector are fixed by an upper connecting seat. Next, the unformed positive electrode material is filled into the tube (T) from the openings at the other ends of the plurality of tubes (T). Next, the openings at the other ends of the plurality of tubes (T) are sealed with a lower connecting seat. In this way, an unformed positive electrode plate is obtained.

[0047] Known materials used in lead-acid batteries may be used for the unformed positive electrode material. The unformed positive electrode material contains a powder containing lead. The powder contains at least lead monoxide. The powder may further contain at least one selected from the group consisting of metallic lead, red lead, and lead sulfate. The unformed positive electrode material may contain additives as necessary.

[0048] The filling of the unformed positive electrode material may be either dry filling or wet filling. For example, in the case of dry filling, the material in a dry state is directly filled into the tube (T). In the case of wet filling, the slurry-like material is filled into the tube (T). The slurry-like material may be adjusted by mixing a powder containing lead, water, sulfuric acid, and additives as required.

[0049] In a conventional clad-type positive electrode plate, in the case of wet filling compared to dry filling, it was difficult in the manufacturing process to fix the core metal on the central axis of the tube, and the core metal was likely to be eccentric. Therefore, when wet filling was performed, variations in the degree of formation were likely to occur. According to the positive electrode plate of the present embodiment, even in the case of wet filling, it is possible to suppress variations in the degree of formation.

[0050] The unformed positive electrode plate is formed. By formation, lead dioxide is generated. The formation may be performed by charging the electrode plate group including the unformed electrode plates while immersing the electrode plate group in the electrolyte in the battery case of the lead storage battery. Alternatively, the formation of the positive electrode plate may be performed before the assembly of the electrode plate group.

[0051] (Lead storage battery) The lead storage battery of the present embodiment generally includes a positive electrode plate, a negative electrode plate, a separator, an electrolyte, a battery case, and a lid. The positive electrode plate is the clad-type positive electrode plate of the present embodiment. There are no particular limitations on the components other than the clad-type positive electrode plate, and known components used in lead storage batteries may be used.

[0052] The battery case houses the positive electrode plate, the negative electrode plate, the separator, and the electrolyte. The separator is disposed between the positive electrode plate and the negative electrode plate. The positive electrode plate, the separator, and the negative electrode plate are laminated to form an electrode plate group. The electrode plate group may include a plurality of positive electrode plates and a plurality of negative electrode plates. The lid seals the opening of the battery case.

[0053] (Negative electrode plate) The negative electrode plate includes a negative electrode current collector and a negative electrode electrode material. The negative electrode electrode material is the part obtained by removing the negative electrode current collector from the negative electrode plate. Note that members such as a mat and a pasting paper may be attached to the negative electrode plate. Since such a member (attached member) is used integrally with the negative electrode plate, it is considered to be included in the negative electrode plate. Further, when the negative electrode plate includes such a member, the negative electrode electrode material is the part obtained by removing the negative electrode current collector and the attached member.

[0054] The negative electrode current collector may be formed by casting lead or a lead alloy, or may be formed by processing a lead or lead alloy sheet. Examples of the processing method include expand processing or punching processing. It is preferable to use a lattice-shaped current collector (negative electrode grid) as the negative electrode current collector because it is easy to support the negative electrode electrode material.

[0055] The lead alloy constituting the negative electrode current collector may be any of a Pb-Sb based alloy, a Pb-Ca based alloy, and a Pb-Ca-Sn based alloy. The lead or lead alloy constituting the negative electrode current collector may contain at least one element selected from the group consisting of Ba, Ag, Al, Bi, As, and Se as an additive element.

[0056] The negative electrode electrode material contains, as an essential component, a negative electrode active material (lead or lead sulfate) that exhibits capacitance by an oxidation-reduction reaction. The negative electrode electrode material may contain additives such as an organic anti-shrinkage agent, a carbonaceous material, and barium sulfate. The negative electrode active material in the charged state is spongy lead, but an unformed negative electrode plate is usually produced using a powder containing lead. The powder containing lead preferably contains lead monoxide and may further contain metallic lead.

[0057] For the organic shrinkage inhibitor, at least one of lignins and synthetic organic shrinkage inhibitors may be used. Examples of lignins include lignin derivatives such as lignin, lignin sulfonic acid or its salts (such as alkali metal salts like sodium salt). The synthetic organic shrinkage inhibitor is an organic polymer containing sulfur element. Examples of the synthetic organic shrinkage inhibitor include, but are not limited to, condensates of aldehyde compounds (aldehydes or their condensates) of compounds having a sulfur-containing group and an aromatic ring.

[0058] (fully charged state) In this specification, the fully charged state of a lead-acid battery means that after constant current charging is carried out in a water tank at 25 °C until reaching 2.8 V / cell with a current (A) that is 0.2 times the numerical value described as the rated capacity (the numerical value with the unit of Ah), further constant current charging is carried out for 2 hours with a current that is 0.2 times the numerical value described as the rated capacity.

[0059] The fully charged lead-acid battery refers to a lead-acid battery obtained by fully charging a preformed lead-acid battery. The full charge of the lead-acid battery may be carried out immediately after formation if it is after formation, or may be carried out after a period of time has elapsed 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 experienced much time elapsed since the start of use and has hardly deteriorated.

[0060] Examples of the carbonaceous material contained in the negative electrode material include carbon black, graphite, etc. Examples of carbon black include acetylene black, furnace black, lamp black, etc. Graphite may be any carbon material containing a graphite-type crystal structure, and may be either artificial graphite or natural graphite.

[0061] There is no limitation to the method for manufacturing the negative electrode plate, and it may be manufactured by the following method. First, water and sulfuric acid are added to the powder containing lead and various additives and kneaded to prepare a negative electrode paste. Next, the negative electrode paste is applied or filled onto the negative electrode current collector, and the obtained electrode plate is aged and dried to obtain an unformed negative electrode plate. Thereafter, a negative electrode plate is obtained by forming the unformed negative electrode plate.

[0062] The formation of the unformed negative electrode plate may be performed by charging the electrode plate group including the unformed negative electrode plate in a state where the electrode plate group is immersed in the electrolytic solution in the battery case of the lead storage battery. Alternatively, the formation may be performed before the assembly of the lead storage battery or the electrode plate group.

[0063] (Separator) A separator disposed between the negative electrode plate and the positive electrode plate is made of a non-woven fabric, a microporous membrane, or the like. The thickness and number of the separators interposed between the negative electrode plate and the positive electrode plate may be selected according to the inter-pole distance, respectively. As the fibers constituting the separator (for example, non-woven fabric), glass fibers, polymer fibers (such as polyester fibers such as polyolefin fibers, acrylic fibers, polyethylene terephthalate fibers, etc.), pulp fibers, etc. can be used. The non-woven fabric may contain components other than fibers (such as inorganic powder, polymer as a binder, etc.).

[0064] The separator may be in a sheet shape, or may be in other shapes (for example, bag shape). Alternatively, the separator may be a separator obtained by bending a sheet-shaped separator into a bellows shape.

[0065] (Electrolytic solution) The electrolytic solution is an aqueous solution containing sulfuric acid. The specific gravity of the electrolytic solution at 20 ° C in a fully charged lead storage battery is, for example, 1.20 or more, and may be 1.23 or more. The specific gravity of the electrolytic solution at 20 ° C is, for example, 1.32 or less, and may be 1.30 or less. The specific gravity of the electrolytic solution at 20 ° C in a fully charged lead storage battery may be 1.20 or more (or 1.23 or more) and 1.32 or less, or 1.20 or more (or 1.23 or more) and 1.30 or less.

[0066] Examples of embodiments of the present invention will be described below with reference to the drawings. The components described above can be applied to the components of the examples described below. Also, the examples described below can be modified based on the above description. Further, the matters described below may be applied to the above embodiments. Also, in the embodiments described below, components that are not essential to the positive electrode plate and the lead storage battery of the present invention may be omitted.

[0067] FIG. 1 is a top view schematically showing a clad-type positive electrode plate 30 according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view taken along line II-II of FIG. 1. FIG. 3 is a schematic cross-sectional view taken along line III-III of FIG. 2. In FIG. 3, the illustration of the upper connecting seat is omitted. FIG. 4 is a cross-sectional view at the first end portion 352a (a cross-sectional view perpendicular to the direction DL). In FIG. 4, hatching is omitted. FIG. 4 also shows the position of the second end portion 352b projected onto the cross-section of FIG. 4. The direction DR shown in some of the figures is the direction in which a plurality of tubes 31 are arranged, and is a direction perpendicular to the direction DL.

[0068] The clad-type positive electrode plate 30 includes a plurality of porous tubes 31 (tubes (T)) arranged in a row, a positive electrode material 32, and a positive electrode current collector 33. The positive electrode current collector 33 includes a plurality of core metals 35 and a current collecting portion 34 connected to each end of the plurality of core metals 35. The plurality of core metals 35 are arranged in a row. One core metal 35 is accommodated in each tube 31. The tube 31 is filled with the positive electrode material 32. Note that the tubes 31 and the core metals 35 not shown in FIGS. 2 and 3 also have the same structure as the structure shown in FIGS. 2 and 3.

[0069] As shown in FIGS. 2 and 3, the core metal 35 is a portion of the positive electrode current collector 33 that is accommodated in the tube 31 and has a surface that is in contact with the positive electrode material 32. One end of each of the plurality of core metals 35 is connected by the current collecting portion 34.

[0070] One end and the other end of a plurality of tubes 31 arranged in a row are fixed by an upper connecting seat 38 and a lower connecting seat 39 respectively. The opening on the current collecting part 34 side of the tube 31 is sealed by a core metal 35 and the upper connecting seat 38. The other opening of each tube 31 is sealed by the lower connecting seat 39. An ear part 34a for collecting current from the clad positive electrode plate 30 is formed at one longitudinal end of the current collecting part 34. The ear part 34a protrudes outward from the upper connecting seat 38. The upper connecting seat 38 and the lower connecting seat 39 are formed of resin or the like.

[0071] The core metal 35 includes a tapered part 351 on the current collecting part 34 side and a rod-shaped part 352 extending from the tapered part 351. The rod-shaped part 352 has a first end 352a on the current collecting part 34 side and a second end 352b on the side opposite to the first end 352a. As shown in FIG. 2, let the length of the core metal 35 in the direction DL in which the tube 31 extends be L0, and the length of the rod-shaped part 352 in the direction DL be L1.

[0072] As shown in FIG. 4, at the first end 352a, the center 352c1 of the rod-shaped part 352 is offset from the center 35c1 of the tube 31. That is, the distance G1 (mm) between the center 352c1 and the center 35c1 at the first end 352a is greater than 0. At the first end 352a, the shortest distance Lmin between the rod-shaped part 352 and the tube 31 is 2.0 mm or less. For ease of understanding, Lmin is shown greater than 0 mm in FIGS. 3 and 4, but in a preferred example, Lmin is 0 mm. In that case, the rod-shaped part 352 contacts the inner peripheral surface of the tube 31. In that case, the distance G1 = 0.5Dt1 - 0.5Db1. Here, Dt1 (mm) is the inner diameter of the tube 31 at the first end 352a, and Db1 (mm) is the diameter of the rod-shaped part 352 at the first end 352a.

[0073] In the cross-section at the first end 352a shown in FIG. 4, on the straight line A passing through the center 352c1 and the center 35c1, there exist a distance Lmin and a distance Lmax as the distances between the rod-shaped portion 352 and the tube 31. The distance Lmax is the longer distance. The distance Lmin may be in the range of 0 to 0.5 times (for example, in the range of 0 to 0.2 times) of the distance Lmax.

[0074] In an example shown in FIG. 4, the center 352c2 of the second end 352b is located in a direction opposite to the center 352c1 of the first end 352a with respect to the central axis of the tube 31. Here, being located in a direction opposite to the center 352c1 of the first end 352a with respect to the central axis of the tube 31 means, for example, in the figure obtained by projecting the cross-section of FIG. 4, being located in the region sandwiched by two lines B whose angle with the straight line A passing through the center 352c1 and the central axis (center 35c1) of the tube 31 is a predetermined angle (for example, 30°). As shown in FIG. 4, the line B is a line starting from the center 352c1.

[0075] In addition, FIGS. 2 to 4 show an example in which the first end 352a of the rod-shaped portion 352 is eccentric in a direction parallel to the in-plane direction of the positive electrode plate 30 with respect to the central axis of the tube 31. However, the first end 352a of the rod-shaped portion 352 may be eccentric in a direction other than the illustrated direction. For example, the first end 352a of the rod-shaped portion 352 may be eccentric in a direction perpendicular to the in-plane direction of the positive electrode plate 30.

[0076] FIG. 5 is a perspective view schematically showing an example in which the lid of the lead storage battery 1 according to an embodiment of the present invention is removed. FIG. 6A is a front view of the lead storage battery of FIG. 5, and FIG. 6B is a schematic cross-sectional view when the cross-section taken along the line VIB-VIB of FIG. 6A is viewed from the arrow direction.

[0077] 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 a plurality of positive plates 30 with a separator 4 interposed therebetween. The positive plate 30 is the clad-type positive plate described above. In this embodiment, a sheet-like separator 4 is sandwiched between the negative plate 2 and the clad-type positive plate 30, but the form of the separator is not particularly limited.

[0078] On each upper portion of the plurality of negative plates 2, there are provided current collecting ears (not shown) that protrude upward. On each upper portion of the plurality of clad-type positive plates 30, 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 30 are connected and integrated by a positive strap 5b. The lower end of a negative terminal post 6a is fixed to the upper portion of the negative strap 5a. The lower end of a positive terminal post 6b is fixed to the upper portion of the positive strap 5b.

[0079] (Evaluation of degree of formation) The degree of formation of the positive electrode material is evaluated by the following procedure using the clad-type positive plate taken out by disassembling the lead-acid battery after the formation is completed. First, for the taken-out positive plate, the portion where the core metal exists is divided into three equal parts: the upper part, the middle part, and the lower part from the current collecting part side along the direction DL in which the tube (T) extends. Then, the positive electrode materials of the upper, middle, and lower parts are taken out separately. Hereinafter, the analysis of the positive electrode material of the upper part will be described, but the positive electrode materials of the middle and lower parts are analyzed in the same manner. About 1.5 g is sampled from the taken-out positive electrode material of the upper part, and its mass W (g) is measured.

[0080] Next, about 1.5 g of the sampled positive electrode material is put into a beaker, and further 50 cm of an acetic acid aqueous solution (concentration: 5 mass%) is added. 3Add. Next, heat the aqueous acetic acid solution in the beaker and bring it to a boil for 10 minutes. By this step, lead monoxide in the positive electrode material is dissolved. Next, after cooling the heated solution, filter it with filter paper (Type 6 of JIS3801-1995), and further wash the residue on the filter paper with distilled water. In this way, the dissolved matter (including dissolved lead monoxide) is removed. Next, pour the above residue (including lead dioxide) into another beaker with distilled water. Further, dissolve the residue remaining on the filter paper with a mixed solution of 10 cm 3 of 30% nitric acid solution and 1 cm 3 of hydrogen peroxide solution, and put it into the beaker. Next, heat the liquid in the beaker to 80 °C for 10 minutes and then cool it. Next, filter the liquid in the beaker and put the filtrate (including dissolved lead dioxide) into a volumetric flask. Further, wash the filter paper with distilled water and put the washing liquid into the volumetric flask, and make the liquid in the volumetric flask 250 cm 3 . Take 50 cm 3 of this filtrate, and add 1 g of tartaric acid and 20 cm 3 of 28 mass% aqueous ammonia solution to it. Add a few drops of BT indicator to the obtained liquid, and then titrate it with a 0.1 mol / L aqueous solution of EDTA (ethylenediaminetetraacetic acid). Take the point where the color of the solution changes from red-violet to blue as the end point of the titration, and record the amount of the EDTA solution at that time. Calculate the content rate (mass%) of lead dioxide by the following formula. FA is the titer of the 0.1 mol / L aqueous solution of EDTA. Content rate (mass%) of PbO2 = 100×(Drop volume of EDTA solution (cm 3 ))×23.92×5×FA / (Mass of sample W (g))

[0081] Since the content rate (mass%) of PbO2 obtained by the above method reflects the degree of formation, use the value of the content rate (mass%) as the value of the degree of formation (%) which is a relative evaluation value of the degree of formation.

[0082] The clad type positive electrode plate and the lead storage battery according to one aspect of the present invention are summarized and described below.

[0083] (1) A clad-type positive electrode plate for a lead-acid battery, comprising at least one porous tube, a positive electrode material filled in the porous tube, and a positive electrode current collector, wherein the positive electrode current collector includes at least one core metal and a current collecting portion connected to an end of the core metal, the core metal is disposed in the tube and is in contact with the positive electrode material, the core metal includes a rod-shaped portion having a first end on the current collecting portion side and a second end opposite to the first end, at the first end, the center of the rod-shaped portion is displaced from the center of the tube, and at the first end, the shortest distance between the rod-shaped portion and the tube is 2.0 mm or less. A clad-type positive electrode plate for a lead-acid battery.

[0084] (2) In the clad-type positive electrode plate for a lead-acid battery according to (1) above, the center of the second end may be located in a direction opposite to the center of the first end with respect to the central axis of the tube.

[0085] (3) In the clad-type positive electrode plate for a lead-acid battery according to (1) or (2) above, at the first end, the distance G1 (mm) between the center of the rod-shaped portion and the center of the tube, the inner diameter Dt1 (mm) of the tube, and the diameter Db1 (mm) of the rod-shaped portion may satisfy (0.5Dt1 - 0.5Db1 - 2.0) ≦ G1 ≦ (0.5Dt1 - 0.5Db1).

[0086] (4) In the clad-type positive electrode plate for a lead-acid battery according to any one of (1) to (3) above, the second end may be in contact with the inner peripheral surface of the tube.

[0087] (5) The clad-type positive electrode plate for a lead-acid battery according to any one of (1) to (4) above may include a plurality of the tubes arranged in a row, and the positive electrode current collector may include a plurality of the core metals each having an end connected to the current collecting portion.

[0088] (6) In the clad-type positive electrode plate for a lead-acid battery according to (5) above, the plurality of the core metals may be inclined in the same direction.

[0089] A lead-acid battery comprising the clad-type positive electrode plate according to any one of (1) to (6) above.

[0090] [Examples] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to the following examples. Note that all of the lead-acid batteries in the following examples are single-cell batteries with a rated voltage of 2V.

[0091] "Lead-acid batteries A1 to A7, CA1 to CA2" (1) Fabrication of the clad-type positive electrode plate The clad-type positive electrode plate having a grid as shown in FIGS. 2 and 3 is fabricated by the following procedure. The fabricated positive electrode plate has substantially the same configuration as the positive electrode plate shown in FIG. 1, except for the number of tubes and grids.

[0092] First, the positive current collector is manufactured by casting. At this time, a plurality of positive current collectors are manufactured by changing the distance between the center of the rod-shaped portion at the first end and the center of the tube (T). Specifically, at the first end, a plurality of positive current collectors are fabricated by changing the shortest distance Lmin between the rod-shaped portion of the grid and the tube (T) so as to be the values shown in Table 1. Note that the rod-shaped portion of the grid is cylindrical (diameter: 3.0 mm). The length L0 of each grid is 295 mm.

[0093] The number of grids included in one positive current collector is 15. The 15 grids of the manufactured positive current collector are accommodated in 15 tubes. Next, the current collecting portion and one end of the tube are covered with resin to form an upper resin connecting seat. The material of the positive current collector is a Pb-Sb-based alloy. A porous tube made of glass fiber is used for the tube. The length of the tube is 310 mm, the outer diameter is 9.5 mm, and the inner diameter is 9.0 mm.

[0094] Next, the positive electrode slurry is filled from the opening of the tube (the opening on the side opposite to the current collector). At this time, the integrated positive current collector and tube are tilted, and the positive electrode slurry is filled with the second end of the core metal in contact with the tube. Specifically, when the rod-shaped portion is eccentric at the first end, the tube is tilted so as to be arranged as shown in FIG. 4, and the positive electrode slurry is filled.

[0095] The positive electrode slurry is prepared by kneading lead powder (containing 80% by mass of lead oxide and 20% by mass of metallic lead), lead red lead, water, and dilute sulfuric acid. The mass ratio of lead powder to lead red lead is 9:1. Next, the opening of the tube is sealed with the lower seat. In this way, an unformed clad positive electrode plate is manufactured. Note that the filling amount of the positive electrode slurry is adjusted so that the positive electrode plate after completion of formation contains 841 ± 8 g of positive electrode active material per sheet in terms of PbO2 after formation.

[0096] (2) Fabrication of negative electrode Lead powder (containing 80% by mass of lead oxide and 20% by mass of metallic lead), 0.15% by mass of an organic anti-shrinkage agent (sodium lignin sulfonate), and 1.2% 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 made of an Sb-based alloy as a negative current collector and dried to produce an unformed negative electrode plate. At this time, a negative electrode plate (negative electrode plate A) with a thickness of 2.7 mm is manufactured using a grid-shaped current collector with a thickness of 2.6 mm, and a negative electrode plate (negative electrode plate B) with a thickness of 4.5 mm is manufactured using a grid-shaped current collector with a thickness of 4.4 mm. The same number of negative electrode plates A and B are manufactured. The filling amount of the negative electrode paste is adjusted so that the amount of negative electrode active material contained in one negative electrode plate A is 420 ± 6 g in terms of Pb, and the amount of negative electrode active material contained in one negative electrode plate B is 750 ± 6 g in terms of Pb. The length of the negative electrode plate is the same as the length of the tube of the positive electrode plate, and the width of the negative electrode plate is the same as the width of the positive electrode plate.

[0097] (3) Fabrication of lead storage battery Four unformed negative plates and three unformed clad positive plates are stacked alternately with a separator (a microporous membrane made of polypropylene) interposed therebetween. Thereby, a plate group as shown in FIG. 6B is formed. As the two outer negative plates of the plate group, negative plate A is used, and as the two inner negative plates, negative plate B is used.

[0098] Next, the plate group is housed in a polypropylene battery case, and dilute sulfuric acid (concentration: 14% by mass) is poured into the battery case. Next, a lid is adhered to the opening of the battery case. Next, formation is carried out while maintaining the battery case in a water bath at 30°C. The formation is carried out by high-speed formation. The high-speed formation is carried out by passing a formation current of 31.5 A at a constant current for a formation time of 40 hours. In this way, lead-acid batteries A1 to A7 and CA1 to CA2 are obtained.

[0099] (4) Evaluation of the degree of formation The degree of formation of the positive electrode material of the above lead-acid battery is evaluated according to the described procedure.

[0100] Table 1 shows the value of the shortest distance Lmin in the above battery and the degree of formation of the positive electrode material. Table 1 shows the degree of formation of the positive electrode material of each part and the degree of formation of the entire positive electrode material. The degree of formation of the entire positive electrode material is the average value of the degrees of formation of the positive electrode materials of each part. Note that the degree of formation shown in Table 1 is the average value of the evaluation results of three batteries produced for each battery.

[0101]

Table 1

[0102] The core metal of the positive current collector of battery CA1 has the center of the tube and the center of the core metal rod portion coinciding at the end on the current collection part side. That is, the positive current collector of battery CA1 is a general positive current collector that has been conventionally used. Regarding the batteries shown in Table 1, the relationship between the shortest distance Lmin and the degree of formation of the entire positive electrode material is shown in FIG. 7. As shown in Table 1 and FIG. 7, by setting the shortest distance Lmin to 2.0 mm or less, the degree of formation of the entire positive electrode material can be improved. In batteries CA1 and CA2 where the shortest distance is greater than 2.0 mm, the difference in the degree of formation between the upper part and the lower part is large. On the other hand, in batteries A1 to A7 where the shortest distance is 2.0 mm or less, the variation in the degree of formation is small, and as a result, the degree of formation of the entire positive electrode material is high. From the viewpoint of increasing the degree of formation of the entire positive electrode material, it is preferable that the shortest distance Lmin is small, preferably 1.5 mm or less, more preferably 1.0 mm or less, and particularly preferably 0.5 mm or less.

[0103] (Example 2) In Example 2, batteries CB1 and B1 are produced under the same conditions as the above-described batteries CA1 and A6, except that the formation conditions of the positive electrode plate are changed. The positive electrode plate is formed by normal formation instead of high-speed formation. Normal formation is performed by passing a formation current of 18.5 A at a constant current for a formation time of 68 hours. Table 2 shows the value of the shortest distance Lmin and the degree of formation of the positive electrode material in the produced batteries.

[0104]

Table 2

[0105] As shown in Table 2, the degree of formation of the entire positive electrode material of battery B1 where the shortest distance Lmin is 2.0 mm or less is higher than that of battery CB1. Thus, even when normal formation is performed, it is effective to set the shortest distance Lmin to 2.0 mm or less.

Industrial Applicability

[0106] The present invention is used for a clad positive electrode plate and a lead storage battery including the same. There is no limitation on the use of the lead storage battery, and it can be used for various applications. The lead storage battery of the present invention is preferably used for an industrial long-life battery and a battery for an electric vehicle (such as a forklift). Further, the lead storage battery of the present invention may be used for a battery for vehicles such as an automobile and a motorcycle.

Explanation of Reference Numerals

[0107] 1: Lead storage battery 30: Clad positive electrode plate 30: Positive electrode plate 31: Tube 32: Positive electrode material 33: Positive electrode current collector 34: Current collecting portion 35: Core wire 35c1, 352c1, 352c2: Center 352: Rod-shaped portion 352a: First end 352b: Second end

Claims

1. At least one porous tube, a positive electrode material filled in the porous tube, and a positive current collector, and the positive current collector includes at least one core metal and a current collecting portion connected to an end of the core metal, the core metal is disposed in the tube and is in contact with the positive electrode material, the core metal includes a rod-shaped portion having a first end on the current collecting portion side and a second end opposite to the first end, at the first end, the center of the rod-shaped portion is offset from the center of the tube, at the first end, the shortest distance between the rod-shaped portion and the tube is 2.0 mm or less, a clad type positive electrode plate for a lead storage battery, wherein the center of the second end is located in a direction opposite to the center of the first end across the central axis of the tube.

2. At least one porous tube, a positive electrode material filled in the porous tube, and a positive current collector, and the positive current collector includes at least one core metal and a current collecting portion connected to an end of the core metal, the core metal is disposed in the tube and is in contact with the positive electrode material, the core metal includes a rod-shaped portion having a first end on the current collecting portion side and a second end opposite to the first end, at the first end, the center of the rod-shaped portion is offset from the center of the tube, at the first end, the shortest distance between the rod-shaped portion and the tube is 2.0 mm or less, the tube is cylindrical, a clad type positive electrode plate for a lead storage battery, wherein there is one core metal disposed in one of the tubes.

3. The clad type positive electrode plate for a lead storage battery according to claim 1 or 2, wherein at the first end, the distance G1 (mm) between the center of the rod-shaped portion and the center of the tube, the inner diameter Dt1 (mm) of the tube, and the diameter Db1 (mm) of the rod-shaped portion satisfy (0.5Dt1 - 0.5Db1 - 2.0) ≦ G1 ≦ (0.5Dt1 - 0.5Db1).

4. The clad type positive electrode plate for a lead storage battery according to any one of claims 1 to 3, wherein the second end is in contact with the inner peripheral surface of the tube.

5. including a plurality of the tubes arranged in a row, the clad type positive electrode plate for a lead storage battery according to any one of claims 1 to 4, wherein the positive current collector includes a plurality of the core metals each having an end connected by the current collecting portion.

6. The clad type positive electrode plate for a lead storage battery according to claim 5, wherein the plurality of the core metals are inclined in the same direction.

7. A lead storage battery including the clad type positive electrode plate for a lead storage battery according to any one of claims 1 to 6.

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