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 positive electrode plate includes at least one porous tube 31, a positive electrode material 32 filling the tube, and a positive electrode current collector 33. The positive electrode current collector includes at least one core grid 35 with first and second end parts, and a current collector part 34 connecting to the first end part 35a. The core grid is disposed in the tube, and is in contact with the positive electrode material. The core grid includes at least one fin 352 protruding from a surface of a core part 351. The fin includes a function unit in which a height Hf (mm) from a central axis of the core part and an inner diameter Dt (mm) of the tube satisfy (0.5Dt-2.0)≤Hf≤0.5Dt. A ratio Lf / L0 of a total length Lf of a core grid part including the function unit in a direction where the tube extends to a length L0 of the core grid in the same direction is 0.05 or more.SELECTED DRAWING: Figure 2

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 accommodated 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]

[0004] Patent Document 1 (Japanese Utility Model Publication No. 49-113), Patent Document 2 (Japanese Patent Application Laid-Open No. 56-167272), and Patent Document 3 (Japanese Patent Application Laid-Open No. 8-203505) disclose a positive electrode current collector including a core metal formed with a plurality of protrusions or a plurality of blades.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] ​ In a conventional clad-type positive electrode plate, there are cases where the degree of formation of the positive electrode material cannot be sufficiently increased. In such a situation, one of the objects 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 tube, and a positive electrode current collector. The positive electrode current collector includes at least one core bar having first and second ends, and a current collecting portion connected to the first end. The core bar is disposed in the tube and is in contact with the positive electrode material. The core bar includes a core portion and at least one fin protruding from the surface of the core portion. The fin includes a functional portion in which the height Hf (mm) of the fin from the central axis of the core portion and the inner diameter Dt (mm) of the tube satisfy (0.5Dt - 2.0) ≤ Hf ≤ 0.5Dt. The ratio Lf / L0 of the total length Lf of the core bar portion where the functional portion exists in the direction to the length L0 of the core bar in the direction in which the tube extends is 0.05 or more, and at least a part of the functional portion is formed in a region between the first end and a position at a length of 0.6L0 from the first end.

[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 that can increase 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 5A

Figure 5B

Figure 6

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 positive electrode plate of this embodiment is used in a lead-acid battery. The positive electrode plate includes at least one porous tube, a positive electrode material filled in the 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 grid having first and second ends, and a current collecting portion connected to the first end. The grid is disposed in the tube and is in contact with the positive electrode material. The grid includes a core portion and at least one fin protruding from the surface of the core portion. The fin includes a functional portion where the height Hf (mm) of the fin from the central axis of the core portion and the inner diameter Dt (mm) of the tube satisfy (0.5Dt - 2.0) ≤ Hf ≤ 0.5Dt. The ratio Lf / L0 of the total length Lf of the grid portion where the functional portion exists in the direction in which the tube extends to the length L0 of the grid in the same direction is 0.05 or more. At least a part of the functional portion is formed in a region between the first end and a position at a length of 0.6L0 from the first end. This region may be hereinafter referred to as "region (R)".

[0013] The direction in which the tube (T) extends may be hereinafter referred to as "direction DL". 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] The fin is a plate-like protruding portion. The fin is formed to extend parallel to direction DL. The fin may protrude in a direction parallel to the in-plane direction of the positive electrode plate, or may protrude in another direction (for example, a direction perpendicular to the in-plane direction of the positive electrode plate). From the perspective of reducing the variation in the degree of formation, it is preferable that the fins formed on the plurality of grids all protrude in the same direction.

[0015] When the core portion is cylindrical, the central axis of the core portion is the center of the circular cross-section (cross-section perpendicular to direction DL) of the core portion. When the core portion is not cylindrical, the position of the centroid of the cross-section (cross-section perpendicular to direction DL) of the core portion can be regarded as the position of the central axis of the core portion. That is, in this case, a line connecting the centroids along direction DL can be regarded as the central axis.

[0016] 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. 6.

[0017] The positive electrode plate shown in FIG. 6 includes a tube 1031, a positive electrode electrode 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 electrode 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. 6, the portion away from the tube 1031 may be referred to as a separation portion 1035a, and the 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. 6, the core metal 1035 at a position close to the current collecting portion 1034 is the separation portion 1035a, and the core metal 1035 at a position away from the current collecting portion 1034 is the proximity portion 1035b.

[0018] The positive electrode material contains a large amount of lead monoxide PbO with low electrical conductivity (hereinafter sometimes referred to as "unformed active material"). Also, the ions involved in the forming reaction move through the pores of the positive electrode material. Therefore, in the positive electrode material around the vicinity portion 1035b, the resistance of the unformed active material and the resistance when the ions pass through the pores are relatively small. For this reason, in the vicinity of the vicinity portion 1035b, a larger 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 material around the vicinity portion 1035b, due to the originally small resistance and the electrical conductivity that improves as the forming progresses, the forming reaction proceeds rapidly.

[0019] Forming also proceeds simultaneously in the negative electrode plate facing the positive electrode plate. Therefore, also in the negative electrode plate, forming proceeds first from the negative electrode material in the portion facing the vicinity portion 1035b. When the forming of the active material is almost completed in the positive electrode material around the vicinity portion 1035b and the negative electrode material in the portion facing the vicinity portion 1035b (for example, in the latter stage of forming), most of the forming current flows into the separation portion 1035a. However, in addition to the current density increasing due to the concentration of the forming current in the separation portion 1035a, since the resistance of the positive electrode material around the separation portion 1035a is originally large, in the separation portion 1035a, the increase rate of PbO2 (that is, the forming efficiency) with respect to the applied amount of electricity is significantly lower than that of the vicinity portion 1035b.

[0020] Due to the mechanism as described above, in the conventional clad type positive electrode plate having an eccentric core metal, compared with the positive electrode plate provided with a non-eccentric core metal, the variation in the degree of forming of the positive electrode material in the entire positive electrode plate becomes larger, and the degree of forming of the positive electrode material itself in the entire positive electrode plate tends to decrease.

[0021] Note that the variation in the degree of formation of the positive electrode material is relatively small when the formation current applied during formation is small. However, when the formation current is large (for example, when high-speed formation is performed), in the initial stage of formation, the difference between the formation current density in the proximity portion 1035b and the formation current density in the spaced-apart portion 1035a becomes extremely large. Furthermore, in the later stage of formation when the formation of the proximity portion 1035b is almost completed, the formation current concentrates in the spaced-apart portion 1035a with high resistance, resulting in a decrease in the formation efficiency. Therefore, when the formation current is large, the variation in the degree of formation of the positive electrode material becomes significant.

[0022] The core metal of the positive current collector used in this embodiment includes fins having functional portions. The functional portions have a predetermined height and length and are formed at positions away from the tip (second end) of the core metal. The inventors of the present application have newly found that by using the positive current collector including the above functional portions, the degree of formation of the entire positive electrode material can be increased. That is, this functional portion with a small distance between the tube or the electrolytic solution and the current collecting portion (core metal) serves as the starting point of the formation reaction because the resistance in the formation reaction process is smaller. As a result, the formation proceeds rapidly. The present invention is based on this new finding.

[0023] In the positive current collector used in this embodiment, the distance between the functional portion and the tube (T) is small. Therefore, unlike the example shown in FIG. 6, it is possible to suppress the concentration of the formation current only in the proximity portion 1035b of the core metal at the initial stage of formation. As a result, the degree of formation of the entire positive electrode material can be increased.

[0024] The core metal has first and second ends. The core metal is a portion of the positive current collector that has a surface in contact with the positive electrode material. The current collecting portion is not in contact with the positive electrode material. The first end is present at the boundary between the core metal and the current collecting portion. The second end is the end on the side opposite to the first end.

[0025] In the functional part, the fin height Hf (mm) and the inner diameter Dt (mm) of the tube satisfy (0.5Dt - a) ≦ Hf ≦ 0.5Dt. As described above, the value a is 2.0 or less, and may be 1.5 or less, 1.25 or less, 1.0 or less, or 0.6 or less. a may be in the range between these upper and lower limits (for example, 0 or more). For example, a may be in the range of 0 to 2.0 (for example, in the range of 0 to 1.5, in the range of 0 to 1.25, in the range of 0 to 1.0, or in the range of 0 to 0.6).

[0026] a may be 0. When a is 0, Hf = 0.5Dt. In the region where the position of the central axis of the core part coincides with the position of the central axis of the tube, when a is 0, the functional part contacts the inner peripheral surface of the tube.

[0027] There is no particular limitation on the thickness of the fin and the functional part included therein. The thickness may be 0.1 mm or more, 0.2 mm or more, or 0.3 mm or more, and may be 0.8 mm or less, 0.7 mm or less, 0.6 mm or less, or 0.5 mm or less. These lower and upper limits can be arbitrarily combined. For example, the thickness may be in the range of 0.2 to 0.6 mm, in the range of 0.2 to 0.5 mm, in the range of 0.3 to 0.6 mm, or in the range of 0.3 to 0.5 mm.

[0028] In the positive electrode plate of the present embodiment, it is preferable that the functional part is formed only in the region (R). For example, it is preferable that the fins are formed only in the region (R). In the above-mentioned patent documents, examples are illustrated in which protrusions and blades are formed on the tip side (second end side) of the core metal. However, if there are protrusions or blades in the vicinity of the tip of the core metal, when filling the tube (T) with the positive electrode material, variations in the filling density of the positive electrode material are likely to occur due to the influence of the protrusions and blades. Furthermore, if a blade or the like near the tip of the core metal comes into contact with the tube (T), current is more likely to concentrate at the tip where the rod-shaped portion of the core metal is already in contact with the tube due to the eccentricity of the core metal. As a result, current does not concentrate on the current collecting portion side (the separated portion 1035a in FIG. 6) at the initial stage of formation, and as a result, variations in the degree of formation cannot be suppressed. On the other hand, by forming the functional part (fins) only in the region (R), variations in the filling density of the positive electrode material can be suppressed. Furthermore, by forming the functional part (fins) only in the region (R), a larger current can be distributed to the region (R), suppressing variations in the degree of formation and improving the degree of formation of the entire positive electrode plate.

[0029] The functional part may be formed only in the region between the first end and the position at a length of 0.43L0 (or 0.37L0, 0.30L0, or 0.25L0) from the first end.

[0030] There is no limitation on the length L0 of the core metal 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).

[0031] In the positive electrode plate of the present embodiment, the core part may include a rod-shaped part. The rod-shaped part means a region having a substantially constant diameter. For example, the rod-shaped part may be a part where the maximum diameter and the minimum diameter of the rod-shaped part are within the range of ±15% (preferably ±5%) of their average value. 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 circular, 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.

[0032] The rod-shaped portion typically has a cylindrical shape. There is no particular limitation on the diameter (e.g., the diameter) of the rod-shaped portion, and it may be in the range of 0.25 to 0.45 times the inner diameter of the tube (e.g., in the range of 0.30 to 0.38 times). The rod-shaped portion may have a shape other than a cylindrical shape (e.g., a prismatic shape).

[0033] In the positive electrode plate of the present embodiment, in a cross-section perpendicular to the direction DL in which the tube (T) extends and passing through the rod-shaped portion, the cross-sectional area Sf (mm 2 ) of the fin, the cross-sectional area St (mm 2 ) inside the tube (T) in the cross-section, and the cross-sectional area Sc (mm 2 ) of the core portion in the cross-section may satisfy Sf ≦ 0.03(St - Sc) over the entire portion of the rod-shaped portion. That is, in any of the above cross-sections, the cross-sectional area Sf of the fin may be 3% or less of (St - Sc). By satisfying these conditions, it is possible to suppress the reduction in the filling amount of the positive electrode material in the portion where the fin is formed due to the fin, and maintain high battery capacity and high cycle characteristics.

[0034] In the positive electrode plate of the present embodiment, the functional portion may be continuously formed from the first end portion toward the second end portion side.

[0035] In the positive electrode plate of the present embodiment, the length Lf may be 0.05L0 or more, 0.1L0 or more, 0.2L0 or more, 0.3L0 or more, or 0.4L0 or more. Note that the length Lf may be 0.6L0 or less, or 0.5L0 or less. These lower limits and upper limits can be arbitrarily combined. For example, the length Lf may be in the range of 0.05L0 to 0.6, or in the range of 0.05 to 0.5L0. These lower limits of the ranges may be 0.1L0, 0.2L0, 0.3L0, or 0.4L0.

[0036] In this specification, the length along the direction DL of one functional part may be referred to as "length La". In the positive electrode plate of the present embodiment, the total of the lengths La of all the functional parts may be 0.98L0 or less. From the viewpoint of increasing the filling amount of the positive electrode material, the total of the lengths La of all the functional parts is preferably 0.74L0 or less, and more preferably 0.60L0 or less. In a preferred example of the positive electrode plate of the present embodiment, the length La of one functional part satisfies the relationship satisfied by the length Lf.

[0037] The number of fins included in the core bar may be one or a plurality (for example, two). In the positive electrode plate of the present embodiment, the number of fins included in one core bar may be one. In this case, the number of functional parts included in one core bar is 1. Alternatively, one core bar may include only two fins symmetrically arranged with the core part interposed therebetween as the at least one fin. In this case, the number of functional parts included in one core bar is 2.

[0038] The above-mentioned patent documents disclose an example in which four or more protrusions or blades are formed on one core bar. By setting the number of fins formed on one core bar to 2 or less, the variation in the filling density of the positive electrode active material can be reduced.

[0039] In the positive electrode plate of the present embodiment, the core bar may be made of an alloy containing lead and antimony.

[0040] Generally, 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 bars each having a first end connected to a current collecting part. The number of tubes (T) is the same as the number of core bars. There is no limitation on the number of tubes (T) and core bars, and they may be in the range of 1 to 30 (for example, in the range of 3 to 20), respectively.

[0041] (Lead-acid battery) The lead-acid battery of the present embodiment includes the clad-type positive electrode plate for the lead-acid battery of the present embodiment. As a result, it becomes possible to suppress the initial self-discharge of the battery and also 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.

[0042] Hereinafter, examples of the main components of the clad-type positive electrode plate of the present embodiment and the lead-acid battery including the same 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.

[0043] (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 characteristics described above. The clad-type positive electrode plate usually includes a connecting seat that connects a plurality of tubes (T). The positive electrode current collector has the characteristics described above.

[0044] (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 necessary.

[0045] 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 shape (including a shape similar to a frustum). 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 cylinder). 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 in the gap between a part of the tapered portion and the columnar portion and the inner peripheral surface of the tube.

[0046] There is no particular limitation on the method for manufacturing 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 die casting method). According to the casting method, a core metal having fins can be easily formed.

[0047] (porous tube) The porous tube (tube (T)) houses the core metal and the positive electrode material therein. The tube (T) as a whole has a hollow cylindrical shape. The tube (T) is porous and the electrolytic solution can pass through it. 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), resin fibers, and the like. The tube (T) may be heat-treated as necessary. The tube (T) may be formed by impregnating a tubular fiber aggregate with a resin.

[0048] 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.

[0049] 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 the cross-section perpendicular to the longitudinal direction of the tube (T). 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 perfect circle.

[0050] There is no particular limitation on the thickness of the tube (T), and it may be a thickness that functions as a tube of the 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).

[0051] The positive electrode material 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.

[0052] There is no limitation on the manufacturing method of the clad type positive electrode plate, and it may be manufactured, for example, by the following method. First, each of the plurality of core metals is accommodated in a plurality of tubes (T). Next, an unformed positive electrode material (a material that becomes a 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.

[0053] When filling the unformed positive electrode material into the tube (T), the tube (T) may be tilted in a predetermined direction for filling. For example, the tube (T) may be tilted for filling so that the second end portion and the tube (T) are in contact with each other in the direction in which the fins protrude. By tilting in such a manner, it becomes easy to realize the arrangement as shown in FIG. 2.

[0054] 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 opening at the other end of each of the plurality of tubes (T). Next, the opening at the other end of each of the plurality of tubes (T) is sealed with a lower connecting seat. In this way, an unformed positive electrode plate is obtained.

[0055] As the unformed positive electrode material, a known material used in lead-acid batteries may be used. 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, lead red oxide, and lead sulfate. The unformed positive electrode material may contain an additive as necessary.

[0056] 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, a 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 an additive as necessary.

[0057] In a conventional clad-type positive electrode plate, in the case of wet filling compared to dry filling, it is difficult in the manufacturing process to fix the grid core on the central axis of the tube, and the grid core 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.

[0058] The unformed positive electrode plate is formed. Lead dioxide is generated by the formation. The formation may be performed by charging the electrode plate group including the unformed electrode plate in a state where the electrode plate group is immersed in the electrolyte in the battery case of the lead-acid battery. Alternatively, the formation of the positive electrode plate may be performed before the assembly of the electrode plate group.

[0059] (Lead-acid battery) The lead-acid battery of this 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 this embodiment. There are no particular limitations on the components other than the clad-type positive electrode plate, and known components used in lead-acid batteries may be used.

[0060] 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.

[0061] (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 portion of the negative electrode plate excluding the negative electrode current collector. Note that members such as a mat and pasting paper may be attached to the negative electrode plate. Since such a member (pasting member) is used integrally with the negative electrode plate, it is included in the negative electrode plate. Further, when the negative electrode plate includes such a member, the negative electrode electrode material is the portion excluding the negative electrode current collector and the pasting member.

[0062] 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 carry the negative electrode electrode material.

[0063] 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.

[0064] The negative electrode material contains, as an essential component, a negative electrode active material (lead or lead sulfate) that exhibits capacitance through a redox reaction. The negative 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.

[0065] As the organic anti-shrinkage agent, at least one of lignins and synthetic organic anti-shrinkage agents 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 salts). The synthetic organic anti-shrinkage agent is an organic polymer containing sulfur element. Examples of the synthetic organic anti-shrinkage agent 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.

[0066] (Fully charged state) In this specification, the fully charged state of a lead-acid battery refers to the state after constant current charging is performed until reaching 2.8 V / cell with a current (A) that is 0.2 times the numerical value described as the rated capacity (a numerical value with the unit of Ah) in a water tank at 25°C, and then further performing constant current charging for 2 hours with a current that is 0.2 times the numerical value described as the rated capacity.

[0067] A fully charged lead-acid battery refers to a lead-acid battery obtained by fully charging a formed lead-acid battery. The full charge of a lead-acid battery may be performed immediately after formation if it is after formation, or may be performed after a certain 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 elapsed much time since the start of use and has hardly deteriorated.

[0068] Examples of the carbonaceous material contained in the negative electrode material include carbon black, graphite, and the like. Examples of carbon black include acetylene black, furnace black, lamp black, and the like. Graphite may be any carbon material having a graphite-type crystal structure, and may be either artificial graphite or natural graphite.

[0069] There is no limitation on 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, the negative electrode plate is obtained by forming the unformed negative electrode plate.

[0070] 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 assembling the lead storage battery or the electrode plate group.

[0071] (Separator) Non-woven fabrics, microporous membranes, and the like are used for the separator disposed between the negative electrode plate and the positive electrode plate. 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, and polyethylene terephthalate fibers), pulp fibers, and the like can be used. The non-woven fabric may contain components other than fibers (such as inorganic powders and polymers as binders).

[0072] The separator may be in a sheet shape or 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.

[0073] (Electrolyte) The electrolyte is an aqueous solution containing sulfuric acid. The specific gravity of the electrolyte at 20°C in a fully charged lead-acid battery is, for example, 1.20 or more, and may be 1.23 or more. The specific gravity of the electrolyte at 20°C is, for example, 1.32 or less, and may be 1.30 or less. The specific gravity of the electrolyte at 20°C in a fully charged lead-acid 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.

[0074] 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. Also, 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-acid battery of the present invention may be omitted.

[0075] 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 schematically shows a cross-section passing through the functional part 352a and perpendicular to the direction DL in which the tube 31 extends. In FIG. 3, the illustration of the positive electrode material 32 is omitted.

[0076] 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 current collecting part 34 and a plurality of grid bars 35. The plurality of grid bars 35 are arranged in a row. One grid bar 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 grid bars 35 not shown in FIGS. 2 and 3 also have the same structure as the structure shown in FIGS. 2 and 3.

[0077] As shown in FIG. 2, the current collector 35 is a portion of the positive current collector 33 that is housed in the tube 31 and has a surface that contacts the positive electrode material 32. The current collector 35 has a first end 35a and a second end 35b. One ends (the first ends 35a) of the plurality of current collectors 35 are connected by the current collecting portion 34.

[0078] One ends and the other ends of the plurality of tubes 31 arranged in a row are fixed by the upper connecting seat 38 and the lower connecting seat 39, respectively. The opening on the current collecting portion 34 side of the tube 31 is sealed by the current collector 35 and the upper connecting seat 38. The other opening of each tube 31 is sealed by the lower connecting seat 39. An ear portion 34a for collecting current from the clad type positive electrode plate 30 is formed at one longitudinal end of the current collecting portion 34. The ear portion 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.

[0079] The current collector 35 includes a core portion 351 and fins 352 protruding from the surface of the core portion 351 toward the inner peripheral surface of the tube 31. In the cross section shown in FIG. 3, the fins 352 protrude along the radial direction of the columnar core portion 351. In an example shown in FIGS. 2 and 3, the core portion 351 includes a tapered portion 351a on the current collecting portion 34 side and a rod-shaped portion 351b extending from the tapered portion 351a.

[0080] A part of the fin 352 is the functional part 352a. The functional part 352a is the part of the fin 352 where the height Hf (mm) of the fin 352 from the central axis 351t of the core part 351 and the inner diameter Dt (mm) of the tube 31 satisfy (0.5Dt - 2.0) ≦ Hf ≦ 0.5Dt. In FIG. 3, an example is shown where the position of the central axis 351t of the core part 351 coincides with the position of the central axis 31t of the tube 31 and Hf = 0.5Dt. The ratio Lf / L0 of the total length Lf of the core part where the functional part 352a exists in the direction DL to the length L0 of the core wire 35 in the direction DL in which the tube 31 extends is 0.05 or more. The functional part 352a is formed in the region R between the first end part 35a and the position at a length of 0.6L0 from the first end part 35a. According to these configurations, the degree of formation of the positive electrode material can be increased.

[0081] The core wire 35 is usually formed such that the central axis of the tapered part 351a coincides with the central axis of the tube 31. Further, the core wire 35 is usually formed such that the central axes of both coincide at the boundary between the tapered part 351a and the rod-shaped part 351b.

[0082] Let the cross-sectional area of the fin 352 in a cross-section perpendicular to the direction DL in which the tube 31 extends and passing through the rod-shaped part 351b (FIG. 3) be Sf (mm 2 ), let the cross-sectional area inside the tube 31 in the said cross-section be St (mm 2 ), and let the cross-sectional area of the core part 351 in the said cross-section be Sc (mm 2 ). In all of the above cross-sections, it is preferable that Sf, St, and Sc satisfy Sf ≦ 0.03(St - Sc) over the entire part of the rod-shaped part 351b.

[0083] In an example shown in FIG. 2, the second end portion 35b is inclined in the same direction as the direction in which the fins 352 (functional portions 352a) protrude, and is in contact with the inner peripheral surface of the tube 31. Also, in an example shown in FIG. 2, the fins 352 protrude along a direction perpendicular to the in-plane direction of the positive electrode plate 30. However, the fins 352 may protrude along another direction (for example, the in-plane direction of the positive electrode plate 30). Here, the in-plane direction of the positive electrode plate is a direction parallel to the plane of the paper in FIG. 1, and is a direction parallel to both the direction in which the tubes 31 are arranged and the direction DL in which the tubes 31 extend. The fins protruding along the in-plane direction of the positive electrode plate 30 have the advantage of being easily formed by casting.

[0084] FIG. 4 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. 5A is a front view of the lead storage battery of FIG. 4, and FIG. 5B is a schematic cross-sectional view when the cross-section taken along line VB-VB of FIG. 5A is viewed from the arrow direction.

[0085] The lead storage 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 electrode plates 2 and a plurality of positive electrode plates 30 with a separator 4 interposed therebetween. The positive electrode plate 30 is the clad type positive electrode plate described above. In this embodiment, a state in which a sheet-like separator 4 is sandwiched between the negative electrode plate 2 and the positive electrode plate 30 is shown, but the form of the separator is not particularly limited.

[0086] On the upper part of each of the plurality of negative electrode plates 2, there is provided an ear portion (not shown) for current collection that protrudes upward. On the upper part of each of the plurality of clad type positive electrode plates 30, there is also provided an ear portion (not shown) for current collection that protrudes upward. Then, the ear portions of the negative electrode plates 2 are connected and integrated by a negative electrode strap 5a. Similarly, the ear portions of the clad type positive electrode plates 30 are also connected and integrated by a positive electrode strap 5b. The lower end portion of the negative electrode post 6a is fixed to the upper part of the negative electrode strap 5a. The lower end portion of the positive electrode post 6b is fixed to the upper part of the positive electrode strap 5b.

[0087] (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 electrode plate taken out by disassembling the lead storage battery after the formation is completed. When taking out the positive electrode material, the mass (filling amount) of the positive electrode material in each part is measured.

[0088] First, for the taken-out positive electrode plate, the part where the core metal exists is divided into three equal parts: the upper part, the middle part, and the lower part from the current collector side along the direction DL in which the tube (T) extends. Then, the positive electrode materials in the upper part, the middle part, and the lower part are taken out separately. Hereinafter, the analysis of the positive electrode material in the upper part will be described, but the positive electrode materials in the middle part and the lower part are also analyzed in the same manner. About 1.5 g is sampled from the taken-out upper positive electrode material, and its mass W (g) is measured.

[0089] 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% by mass) is added. 3 Next, the acetic acid aqueous solution in the beaker is heated and boiled for 10 minutes. By this step, lead monoxide in the positive electrode material is dissolved. Next, after cooling the heated solution, it is filtered with a filter paper (type 6 of JIS3801-1995), and the residue on the filter paper is further washed with distilled water. In this way, the dissolved matter (including dissolved lead monoxide) is removed. Next, the above residue (including lead dioxide) is poured into another beaker with distilled water. Further, the residue remaining on the filter paper is dissolved using a mixed solution of 10 cm of 30% nitric acid solution and 1 cm of hydrogen peroxide solution and distilled water and put into the beaker. Next, the liquid in the beaker is heated to 80 °C for 10 minutes and then cooled. Next, the liquid in the beaker is filtered, and the filtrate (including dissolved lead dioxide) is put into a volumetric flask. Further, the filter paper is washed with distilled water and the washing liquid is put into the volumetric flask to make the liquid in the volumetric flask 250 cm. 3 and 1 cm of hydrogen peroxide solution 3 Next, 50 cm of this filtrate is aliquoted, and 1 g of tartaric acid and 20 cm of 28% by mass ammonia water are added thereto. 3 to make. 3 Next, 50 cm of this filtrate is aliquoted, and 1 g of tartaric acid and 20 cm of 28% by mass ammonia water are added thereto. 3Add the following. To the resulting liquid, after adding several drops of BT indicator to the resulting solution, titrate with a 0.1 mol / L aqueous solution of EDTA (ethylenediaminetetraacetic acid). Take the point at which the color of the solution changes from reddish purple 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 using the following formula. FA is the titer of the 0.1 mol / L aqueous solution of EDTA. Content rate (mass %) of PbO2 = 100×(Drop amount of EDTA solution (cm 3 ))×23.92×5×FA / (Mass W (g) of sample)

[0090] Since the content rate (mass %) of PbO2 obtained by the above method reflects the degree of formation, the value of the content rate (mass %) is used as the value of the degree of formation (%) which is a relative evaluation value of the degree of formation.

[0091] The clad type positive electrode plate and the lead storage battery according to one aspect of the present invention are summarized below.

[0092] (1) A clad type positive electrode plate for a lead storage battery, comprising at least one porous tube, a positive electrode material filled in the tube, and a positive electrode current collector, wherein the positive electrode current collector includes at least one core metal having first and second ends, and a current collecting portion connected to the first end, the core metal is disposed in the tube and is in contact with the positive electrode material, the core metal includes a core portion and at least one fin protruding from the surface of the core portion, the fin includes a functional portion in which the height Hf (mm) of the fin from the central axis of the core portion and the inner diameter Dt (mm) of the tube satisfy (0.5Dt - 2.0) ≦ Hf ≦ 0.5Dt, and the ratio Lf / L0 of the total length Lf of the core metal portion where the functional portion exists in the direction to the length L0 of the core metal in the direction in which the tube extends is 0.05 or more, and at least a part of the functional portion is formed in a region between the first end and a position at a length of 0.6L0 from the first end, a clad type positive electrode plate for a lead storage battery.

[0093] (2) In the clad type positive electrode plate for a lead storage battery according to (1) above, the functional part may be formed only in the region.

[0094] (3) In the clad type positive electrode plate for a lead storage battery according to (1) or (2) above, the core part may include a rod-shaped part, and in a cross-section perpendicular to the direction in which the tube extends and passing through the rod-shaped part, the cross-sectional area Sf of the fin, the cross-sectional area St inside the tube in the cross-section, and the cross-sectional area Sc of the core part in the cross-section may satisfy Sf ≦ 0.03(St - Sc) over the entire part of the rod-shaped part.

[0095] (4) In the clad type positive electrode plate for a lead storage battery according to any one of (1) to (3) above, the functional part may be continuously formed from the first end portion toward the second end portion side.

[0096] (5) In the clad type positive electrode plate for a lead storage battery according to any one of (1) to (4) above, the length Lf may be 0.3L0 or more.

[0097] (6) In the clad type positive electrode plate for a lead storage battery according to any one of (1) to (5) above, the number of fins included in the core wire may be one.

[0098] (7) In the clad type positive electrode plate for a lead storage battery according to any one of (1) to (6) above, the core wire may include only two fins symmetrically arranged with the core part interposed therebetween as the at least one fin.

[0099] (8) In the clad type positive electrode plate for a lead storage battery according to any one of (1) to (7) above, the core wire may be made of an alloy containing lead and antimony.

[0100] (9) The clad type positive electrode plate for a lead storage battery according to any one of (1) to (8) 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 the first end connected at the current collecting portion.

[0101] (10) A lead storage battery including the clad type positive electrode plate for a lead storage battery according to any one of (1) to (9) above.

[0102] [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 storage batteries in the following examples are single cell batteries with a rated voltage of 2V.

[0103] (Example 1) In Example 1, a plurality of batteries are manufactured and evaluated by changing the length of the core metal portion where the functional portion exists. Specifically, lead storage batteries A1 to A11 and CA1 are manufactured and evaluated according to the following procedure.

[0104] (1) Manufacture of clad type positive electrode plate The positive electrode plate to be manufactured has substantially the same configuration as the positive electrode plate shown in FIGS. 1 to 3 except for the number of tubes and core metals and the direction in which the fins protrude. In the batteries manufactured below, the fins are formed parallel to the in-plane direction of the positive electrode plate.

[0105] First, the positive electrode current collector is manufactured by casting. At this time, a plurality of positive electrode current collectors are manufactured by changing the above ratio Lf / L0 as shown in Table 1. The height of the fin from the central axis of the core metal is (0.5Dt - 1.0) mm. Here, Dt is the inner diameter (mm) of the tube. The diameter of the core portion in the rod-shaped portion is 3.0 mm. The thickness of the fin is 0.5 mm. The fin and the functional portion of the fin are continuously formed from the first end.

[0106] The positive current collectors of batteries A10 and A11 have two fins formed symmetrically with a core part in between. The positive current collector of battery CA1, which is a comparative example, has no fins. The number of core wires included in one positive current collector is 15. The 15 core wires of the manufactured positive current collector are accommodated in 15 tubes. Next, the current collecting part 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. The length L0 of each core wire is 295 mm. A porous tube made of glass fiber is used for the tube. The length of the tube is 310 mm, the outer diameter is 10.0 mm, and the inner diameter is 9.0 mm.

[0107] Next, the positive electrode slurry is filled from the opening of the tube (the opening on the side opposite to the current collecting part). At this time, with the positive current collector and the tube integrated and tilted, the positive electrode slurry is filled in a state where the second end of the core wire is in contact with the tube. Specifically, the positive electrode slurry is filled with the tube tilted so that the second end is tilted in the direction in which the fins protrude. The positive electrode slurry is prepared by kneading lead powder (containing 80% by mass of lead oxide and 20% by mass of metallic lead), red lead, water, and dilute sulfuric acid. The mass ratio of lead powder to red lead is 9:1. Next, the opening of the tube is sealed with a lower connecting seat. In this way, an unformed clad type 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 the positive electrode active material in terms of PbO2 per sheet after formation.

[0108] (2) Fabrication of the 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 lignosulfonate), 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 electrode 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 produced 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 produced using a grid-shaped current collector with a thickness of 4.4 mm. The same number of negative electrode plates A and negative electrode plates B are produced. 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 made the same as the length of the tube of the positive electrode plate, and the width of the negative electrode plate is made the same as the width of the positive electrode plate.

[0109] (3) Fabrication of lead-acid battery Four unformed negative electrode plates and three unformed clad-type positive electrode plates are alternately stacked with a separator (a microporous membrane made of polypropylene) interposed therebetween. Thereby, a group of electrode plates as shown in Fig. 5B is formed. Negative electrode plate A is used as the two outer negative electrode plates of the group of electrode plates, and negative electrode plate B is used as the two inner negative electrode plates.

[0110] Next, the group of electrode plates 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 A11 and CA1 are obtained.

[0111] (4) Evaluation of degree of formation The degree of formation of the positive electrode material of the fabricated lead-acid battery is evaluated according to the described procedure.

[0112] Table 1 shows the value of the ratio Lf / L0 in the manufactured 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. The degree of formation shown in Table 1 is the average value of the results obtained by manufacturing and evaluating six batteries for each battery.

[0113] (Evaluation of cycle life) For the above battery, the cycle life is evaluated. Specifically, first, for each battery, a cycle test is performed by the following method. The cycle test is performed by repeating a charge-discharge process in which a discharge process and a charge process are defined as one cycle. The discharge process is performed by discharging at a constant current (50 A) for 3 hours so as to discharge 75% (150 Ah) of the nominal capacity (200 Ah) of each battery in 3 hours. The charge process is performed by charging at 45 A for 3 hours and then charging at 20 A for 2 hours. In the first charge, 90% of the discharge amount (150 Ah) is charged, and in the entire charge process, 117% of the discharge amount (150 Ah) is charged. These conditions are conditions close to the usage conditions of a forklift battery.

[0114] Every 100 cycles of the cycle test, the discharge capacity of the battery is measured. First, the battery is charged at 40 A for 5 hours to sufficiently stir the electrolyte. Then, at the end of the charge, the specific gravity of the electrolyte is adjusted to 1.280 (converted to 20 °C). Next, after storing the battery in a water tank at 30 °C for 12 hours, the discharge capacity is measured in the water tank under the conditions of a discharge current of 40 A and a cut-off voltage of 1.70 V.

[0115] Let the number of cycles when the measured discharge capacity falls below 135 A be X2, and the discharge capacity at that time be C2. Further, let the discharge capacity at the time of the previous discharge capacity measurement be C1. The life cycle number X is calculated by the following formula. The life cycle number X is shown in Table 1. X = X2 - 100 + 100×(C1 - 135) / (C1 - C2)

[0116]

Table 1

[0117] The filling amount of the positive electrode material in each part is shown in Table 2. In Table 2, the overall filling amount reduction rate is obtained by the following formula based on the filling amount of battery CA1. Overall filling amount reduction rate (%) = 100×(total filling amount of positive electrode material (g) - 803) / 803

[0118] The upper filling amount reduction rate is obtained by the following formula. Upper filling amount reduction rate (%) = 100×(lower filling amount (g) - upper filling amount (g)) / lower filling amount (g)

[0119]

Table 2

[0120] As described above, the fins and functional parts of batteries A1 to A11 are continuously formed from the first end. Therefore, all the functional parts of the fins of batteries A1 to A11 are formed in the region R between the first end and the position where the length from the first end is 0.6L0.

[0121] As shown in Table 1, in battery CA1 without fins, the degree of formation of the upper part close to the current collector is low, and as a result, the degree of formation of the entire positive electrode material is low. On the other hand, in batteries A1 to A11 where Lf / L0 is 0.05 or more, the degree of formation of the entire positive electrode material is high. From the viewpoint of increasing the degree of formation of the positive electrode material, it is preferable to increase the length Lf. On the other hand, from the viewpoints of increasing the filling amount of the positive electrode material and increasing the number of life cycle times, it is preferable to shorten the length Lf.

[0122] When the upper filling amount reduction rate increases, the number of life cycle times decreases. From the viewpoint of the number of life cycle times, batteries A1 to A10 with an upper filling amount reduction rate of 3.0% or less have more life cycle times than battery CA1. For this reason, as described above, the cross-sectional area Sf (mm 2 ) of the fin in the cross-section perpendicular to the direction DL in which the tube (T) extends, and the inner cross-sectional area St (mm of the tube (T) in the cross-section2 ) and the cross-sectional area Sc (mm of the core part in the cross-section 2 ) preferably satisfies Sf ≦ 0.03(St - Sc) over the entire rod-shaped part.

[0123] (Example 2) In Example 2, a plurality of batteries are manufactured and evaluated by changing the height of the functional part. Specifically, lead-acid batteries B1 to B7 and CB1 are manufactured and evaluated according to the following procedure.

[0124] A lead-acid battery is manufactured in the same manner as in Example 1 except that the positive current collector is changed. In Example 2, the height Hf of the functional part is set to (0.5Dt - a) mm, and the value of a is changed as shown in Table 3. Note that the positive current collector of battery CA1 with a = 3 mm has no fins, and the results of battery CA1 in Example 1 are used for the results of battery CB1 in Example 2. Also, battery B5 with a = 1.0 mm is the same as battery A5 in Example 1, and the results of battery A5 are used for the results of battery B5. Lf / L0 is 0.37. The thickness of the fins is 0.5 mm.

[0125] The manufactured batteries are evaluated in the same manner as in Example 1. Some of the manufacturing conditions and the evaluation results are shown in Table 3. Note that the degree of formation shown in Table 3 is the average value of the results of manufacturing and evaluating six batteries for each battery.

[0126]

Table 3

[0127] As shown in Table 3, by setting the a value to 2.0 mm or less, the degree of formation of the entire positive electrode material can be increased.

Industrial Applicability

[0128] 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 suitably used for industrial long-life storage batteries and storage batteries for electric vehicles (such as forklifts). Further, the lead storage battery of the present invention may be used for storage batteries for vehicles such as automobiles and motorcycles.

Explanation of symbols

[0129] 1: Lead storage battery 30: Clad positive electrode plate 30: Positive electrode plate 31: Tube 31t: Central axis 32: Positive electrode material 33: Positive electrode current collector 34: Current collecting part 35: Core wire 35a: First end 35b: Second end 351: Core part 351b: Rod-shaped part 351t: Central axis 352: Fin 352a: Functional part

Claims

1. At least one porous tube, A positive electrode material filled in the tube, And a positive electrode current collector, The positive electrode current collector includes at least one core metal having first and second ends, and a current collecting portion connected to the first end, The core metal is disposed in the tube and is in contact with the positive electrode material, The core metal includes a core portion and at least one fin protruding from the surface of the core portion, The fin includes a functional portion in which the height Hf (mm) of the fin from the central axis of the core portion and the inner diameter Dt (mm) of the tube satisfy (0.5Dt - 2.0) ≤ Hf ≤ 0.5Dt, The ratio Lf / L0 of the total length Lf of the core metal portion where the functional portion exists in the direction to the length L0 of the core metal in the direction in which the tube extends is 0.05 or more, At least a part of the functional portion is formed in a region between the first end and a position at a length of 0.6L0 from the first end, A clad type positive electrode plate for a lead storage battery, wherein the functional portion is formed only in the region.

2. The clad type positive electrode plate for a lead storage battery according to Claim 1, wherein the number of fins included in the core metal is one.

3. At least one porous tube, A positive electrode material filled in the tube, And a positive electrode current collector, The positive electrode current collector includes at least one core metal having first and second ends, and a current collecting portion connected to the first end, The core metal is disposed in the tube and is in contact with the positive electrode material, The core metal includes a core portion and at least one fin protruding from the surface of the core portion, The fin includes a functional portion where the height Hf (mm) of the fin from the central axis of the core portion and the inner diameter Dt (mm) of the tube satisfy (0.5Dt - 2.0) ≤ Hf ≤ 0.5Dt. The ratio Lf / L0 of the total length Lf of the core metal portion where the functional portion exists in the direction to the length L0 of the core metal in the direction in which the tube extends is 0.05 or more. At least a part of the functional portion is formed in a region between the first end portion and a position at a length of 0.6L0 from the first end portion. The core metal includes only two fins symmetrically arranged with the core portion therebetween as the at least one fin, and is a clad type positive electrode plate for a lead storage battery.

4. The core portion includes a rod-shaped portion. In a cross section perpendicular to the direction in which the tube extends and passing through the rod-shaped portion, the cross-sectional area Sf of the fin, the cross-sectional area St inside the tube in the cross section, and the cross-sectional area Sc of the core portion in the cross section satisfy Sf ≤ 0.03(St - Sc) over the entire portion of the rod-shaped portion. The clad type positive electrode plate for a lead storage battery according to any one of claims 1 to 3.

5. The functional portion is continuously formed from the first end portion toward the second end portion side. The clad type positive electrode plate for a lead storage battery according to any one of claims 1 to 4.

6. The length Lf is 0.3L0 or more. The clad type positive electrode plate for a lead storage battery according to any one of claims 1 to 5.

7. The core metal is made of an alloy containing lead and antimony. The clad type positive electrode plate for a lead storage battery according to any one of claims 1 to 6.

8. It includes a plurality of the tubes arranged in a row. The positive electrode current collector includes a plurality of the core metals each having the first end portion connected by the current collecting portion. The clad type positive electrode plate for a lead storage battery according to any one of claims 1 to 7.

9. A lead-acid battery comprising the clad-type positive electrode plate for lead-acid batteries according to any one of claims 1 to 8.

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