lead-acid batteries

Abstract

To provide a lead accumulator battery capable of improving the short circuit resistance between a separator and a positive electrode composed of an active material holding member.SOLUTION: A lead accumulator battery 100 comprises an electrode group 110 in which a negative electrode 20 and a positive electrode 10 that is configured to include an active material holding member 11 composed of a plurality of cylindrical members 12 and a positive electrode material 16 filled in the cylindrical members 12, are laminated via a separator 30. The cylindrical members 12 configuring the active material holding member 11 include a first cylindrical member 12A formed by welding a longitudinal end part 13c of a belt-like base material 13 when the base material 13 is spirally wound. At least a part of a welded portion 70 welded in the first cylindrical member 12A is formed with a projection 71 protruded outside an outer surface of the base material 13 and having a density higher than that of the base material 13. The projection 71 of the cylindrical member 12 is protruded in a direction where the separator 30 is arranged.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] One aspect of the present invention relates to a lead-acid battery. [Background technology]

[0002] Lead-acid batteries are widely used as secondary batteries for industrial or consumer use, and there is particularly high demand for lead-acid batteries for electric vehicles (e.g., automotive lead-acid batteries, so-called batteries), uninterruptible power supplies (UPS), power sources for disaster prevention (emergency) radios, power sources for telephones, and other backup applications.

[0003] In lead-acid batteries, an active material holding member including a plurality of tubular members arranged side by side as tubular members capable of holding (accommodating) active material is sometimes used. For example, a lead-acid battery includes an active material holding member including tubular members, an electrode including a metal core (current collector) inserted into the tubular members, and an electrode material (electrode material containing an active material) filled between the tubular members and the metal core (see, for example, Patent Document 1 listed below). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-203506 Summary of the Invention [Problem to be solved by the invention]

[0005] In such lead-acid batteries, an electrode group is formed in which positive and negative electrodes each made of an active material holding member are stacked with a separator interposed therebetween. Although various measures have been taken to prevent short circuits from occurring in the electrode group, there is a demand for reducing short circuits that occur at the contact point between the positive electrode made of the active material holding member and the separator.

[0006] Therefore, an object of one aspect of the present invention is to provide a lead-acid battery that can improve the short-circuit resistance between the separator and a positive electrode made of an active material holding member. [Means for solving the problem]

[0007] A lead-acid battery according to one aspect of the present invention is a lead-acid battery including an electrode group in which a positive electrode and a negative electrode each including an active material holding member in which tubular members extending in a first direction between a first end and a second end are arranged in a second direction perpendicular to the first direction, and an active material filled in the tubular member are stacked with a separator interposed therebetween, wherein the tubular members constituting the active material holding member include at least one of a first tubular member formed by welding a longitudinal end of a strip-shaped substrate when the substrate is spirally wound from the first end to the second end, and a second tubular member formed by welding a winding-end end of the substrate when the substrate is wound once, and at least a part of the welded portions of the first tubular member and the second tubular member protrudes outward from the outer surface of the substrate, and forms a protruding portion with a density higher than that of the substrate, and at least one of the tubular members of the active material holding member constituting the positive electrode is the first tubular member or the second tubular member, and the protruding portion of the tubular member protrudes in the direction in which the separator is arranged.

[0008] In a lead-acid battery having this configuration, at least one of the cylindrical members of the active material retention member constituting the positive electrode is a first cylindrical member or a second cylindrical member, and the cylindrical member contacts the separator via the protrusion. As a result, even if the cylindrical member of the active material retention member and the separator come into contact with each other, the contact is always via the protrusion. That is, even if the cylindrical member of the active material retention member and the separator come into contact with each other, the outer surface of the cylindrical member and the separator do not come into contact with each other, and a gap is formed between the cylindrical member of the active material retention member and the separator. As a result, the short-circuit resistance between the positive electrode made of the active material retention member and the separator can be improved.

[0009] In a lead-acid battery according to one aspect of the present invention, the tubular member constituting the positive electrode and the separator may be in contact with each other via a protrusion. In this configuration, the outer surface of the tubular member of the active material holding member does not contact the separator, and a gap is formed between the tubular member and the separator. As a result, it is possible to improve the short-circuit resistance between the separator and the positive electrode made of the active material holding member.

[0010] In the lead-acid battery according to one aspect of the present invention, the protrusion may be formed so that the protrusion height from the outer surface of the substrate is 1.02 to 2.00 times the thickness of the substrate. This configuration can more reliably improve the short-circuit resistance between the separator and the positive electrode made of the active material retention member.

[0011] In the lead-acid battery according to one aspect of the present invention, the protrusions may be formed so that their density is 1.4 to 5.0 times that of the substrate. This configuration can increase the durability of the protrusions, which come into contact with the separator.

[0012] In a lead-acid battery according to one aspect of the present invention, the first cylindrical member may be formed such that the entire welded portion extending spirally from the first end to the second end constitutes a protrusion. With this configuration, when constructing an active material retention member in which the cylindrical members are arranged in the second direction, the cylindrical members can be arranged without regard to the direction in which the protrusions are formed, thereby improving production efficiency.

[0013] In the lead-acid battery according to one aspect of the present invention, the plurality of cylindrical members constituting the active material holding member may all be first cylindrical members. In this configuration, it is only necessary to prepare the first cylindrical members when forming the active material holding member, thereby improving productivity.

[0014] In a lead-acid battery according to one aspect of the present invention, at least one first cylindrical member or at least one second cylindrical member may be disposed on one end side and the other end side in the second direction from a center position in the second direction of the active material retention member. With this configuration, when the active material retention member and the separator are disposed in contact with each other in the battery case with the protrusions interposed therebetween, the active material retention member and the separator can be stably disposed. [Effects of the Invention]

[0015] According to one aspect of the present invention, it is possible to improve the short-circuit resistance between the separator and the positive electrode made of the active material holding member. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a cross-sectional view of a lead-acid battery according to one embodiment, as viewed from the Y-axis direction. [Figure 2] FIG. 2 is a cross-sectional view of the lead-acid battery according to one embodiment as viewed from the Z-axis direction. [Figure 3] Fig. 3(A) is a perspective view showing the configuration of a cylindrical member according to one embodiment, and Fig. 3(B) is a perspective view showing the configuration of a cylindrical member according to a modified example. [Figure 4] Fig. 4(A) is a front view illustrating a method for manufacturing a tubular member according to an embodiment, and Fig. 4(B) is a cross-sectional view of the tubular member according to an embodiment as viewed from the extending direction. [Figure 5] FIG. 5 is a partially enlarged front view of an active material holding member according to one embodiment. [Figure 6] FIG. 2 is an enlarged front view of a portion of a laminate according to an embodiment. [Figure 7] Fig. 7(A) is a front view illustrating a method for manufacturing a tubular member according to Modification 2. Fig. 7(B) is a cross-sectional view of the tubular member according to Modification 2 as seen from the extending direction. [Figure 8] Fig. 8(A) is an explanatory diagram showing the types of cylindrical members constituting the active material holding member according to Modification 1. Fig. 8(B) is an explanatory diagram showing the types of cylindrical members constituting the active material holding member according to Modification 2. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, a lead-acid battery according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated descriptions will be omitted.

[0018] In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper or lower limit of a numerical range in a certain stage can be arbitrarily combined with the upper or lower limit of a numerical range in another stage. "A or B" may include either A or B, or may include both. Unless otherwise specified, the materials exemplified in this specification can be used alone or in combination of two or more types. The term "process" does not only refer to an independent process, but also includes a process that cannot be clearly distinguished from other processes as long as the intended effect of the process is achieved.

[0019] An example of a lead-acid battery 100 according to this embodiment will be described using Figures 1 to 6. For ease of description, the drawings may be labeled with an X-axis, a Y-axis, and a Z-axis that are perpendicular to one another. The X-axis direction (third direction) is the direction in which the cylindrical members 12 that constitute the positive electrodes (electrodes) 10 are arranged, the Y-axis direction (second direction) is the direction in which the positive electrodes 10 and the negative electrodes 20 are alternately arranged with the separators 30 interposed therebetween, and the Z-axis direction (first direction) is the direction along the extension direction of the cylindrical members 12 and is an axis along the vertical direction.

[0020] As shown in Figures 1 and 2, a lead-acid battery 100 according to one embodiment includes an electrode group 110, a battery case 120 that houses the electrode group 110, connecting members 130a and 130b connected to the electrode group 110, poles 140a and 140b connected to the connecting members 130a and 130b, a liquid inlet plug 150 that closes the liquid inlet of the battery case 120, and a support member 160 connected to the battery case 120.

[0021] The electrode group 110 includes a plurality of positive electrodes 10, a plurality of negative electrodes 20, and a plurality of separators 30. The positive electrodes 10 and negative electrodes 20 are alternately arranged in the Y-axis direction with the separators 30 interposed therebetween. An electrolyte solution 40 is filled in the space between the separators 30 around the positive electrodes 10. The material of the separator 30 is not particularly limited as long as it prevents electrical connection between the positive electrodes 10 and the negative electrodes 20 and allows the electrolyte solution 40 to pass through. Examples of materials for the separator 30 include a mixture of microporous polyethylene, glass fiber, and synthetic resin.

[0022] The positive electrode 10 is, for example, a plate-shaped electrode and includes an active material holding member 11, a plurality of metal cores 14, a positive electrode material (active material) 16, a lower connecting seat 51, an upper connecting seat 61, a connecting portion 18a, and an ear portion 18b.

[0023] The active material holding member 11 is configured to include a plurality of cylindrical members 12. The plurality of cylindrical members 12 are arranged adjacent to each other in a row along the X-axis direction. The plurality of cylindrical members 12 form a group of tubes (clad tubes) for holding active material. The cylindrical members 12 extend in the Z-axis direction. A structure in which a plurality of cylindrical members 12 are arranged side by side can be formed by cylindrical members 12 that are separate from each other.

[0024] The tubular member 12 extends in one direction (first direction) between the first end 13a and the second end 13b and is formed into a cylindrical shape. The tubular member 12 may be formed into an elliptical or rectangular shape (for example, a square cylinder with rounded corners), etc. The center of gravity of the cross section of the tubular member 12 may be used as the central axis of the tubular member 12. The tubular member 12 is a member for holding an active material of a battery, and can hold (accommodate) the active material inside (internal space) of the tubular member 12. The "active material" includes both an active material after chemical conversion and raw materials for the active material before chemical conversion.

[0025] The substrate 13 may be wound at least once, or may be wound more than once, or may be wound multiple times. In the cylindrical member 12 of this embodiment, the substrate 13 is wound multiple times, and is wound in a spiral shape as shown in Fig. 3(A). "Spiral shape" means that the substrate 13 moves in the extension direction of the central axis while circling a periphery at a predetermined distance from the central axis extending in a predetermined direction.

[0026] 4, the tubular member 12 has end faces perpendicular to the axial direction of the tubular member 12, for example, at the first end 13a and the second end 13b. The end faces may be formed by spirally winding a strip-shaped base material 13 to form the tubular member 12, and then cutting both ends of the tubular member 12 perpendicular to the axial direction of the tubular member 12. The width (size in the short direction) of the strip-shaped base material 13 is 5 mm to 35 mm. Alternatively, by using a base material 13 having a shape that allows for end faces perpendicular to the axial direction of the tubular member 12, the end faces can be formed without cutting both ends.

[0027] When the strip-shaped base material 13 is wound spirally, it is possible to wind it so that the longitudinal ends 13c of the base material 13 (hereinafter referred to as "longitudinal ends 13c") overlap, as in this embodiment, or to wind it so that the base materials 13 do not overlap (so that no overlapping portions of the base materials 13 are formed). The tubular member 12 of this embodiment is formed by winding the strip-shaped base material 13 spirally from the second end 13b toward the first end 13a, with an overlapping portion in which a portion of the inner circumferential side base material 13 is covered by the outer circumferential side base material 13. The overlapping portion has a width of 0.5 mm to 5 mm, and preferably a width of 1 mm to 3 mm. If the width of the overlapping portion is smaller than four times the thickness T0 of the substrate 13 (see Figure 4(B)), the overlapping portion, which is the welded portion, will be more likely to break than the substrate 13 portion, increasing the possibility that it will not be able to withstand the expansion and contraction of the active material that accompanies charging and discharging. Therefore, it is preferable that the width of the overlapping portion be four or more times the thickness T0 of the substrate 13.

[0028] An example of the winding angle θ with respect to the horizontal direction of the base material 13 (the arrangement direction of the tubular members) is 10° to 90°. The winding angle θ is the angle of the base material 13 at the center of the X-axis direction of the tubular member 12 with respect to the horizontal direction when the tubular member 12 is viewed from the Y-axis direction. The range of the winding angle θ is preferably 30° to 50°, and more preferably 35° to 45°. Note that in FIGS. 4 and 5, the angle of the base material 13 is depicted as being uniformly the same regardless of the position in the X-axis direction of the tubular member 12; however, when viewed from the Y-axis direction, the angle actually appears to become steeper as it approaches the end in the X-axis direction.

[0029] The tubular member 12 is formed by spirally winding a strip-shaped substrate 13 from a first end 13a to a second end 13b and then welding (e.g., ultrasonically welding) a longitudinal end 13c of the substrate 13. As shown in FIGS. 4(A) and 4(B), at least a portion of the welded portion 70 in the tubular member 12 protrudes outward from the outer surface of the substrate 13, forming a protruding portion 71 having a density higher than that of the substrate 13. In other words, the amount of voids formed in the protruding portion 71 is smaller than the amount of voids formed in the substrate 13. In yet another way, the amount of resin per unit volume in the protruding portion 71 is greater than the amount of resin per unit volume in the substrate 13. The tubular member 12 of this embodiment is formed such that the entire welded portion 70 extending spirally from the first end 13a to the second end 13b becomes the protruding portion 71. 4(A) and 4(B) will be referred to hereinafter as a “first cylindrical member 12A.” All of the multiple cylindrical members 12 constituting the active material holding member 11 of this embodiment are this first cylindrical member 12A.

[0030] The protrusion height (protrusion amount) T of the protrusions 71 of the cylindrical member 12 thus formed, i.e., the protrusion height T from the outer surface of the substrate 13, is, for example, 0.01 mm to 0.3 mm. The protrusion height T of the protrusions 71 is formed to be 1.02 to 2.00 times the thickness T0 of the substrate 13. The protrusions 71 are also formed to have a density 1.4 to 5.0 times the density of the substrate 13. The protrusions 71 protrude in a direction along which adjacent cylindrical members 12 face each other. In the positive electrode 10 of this embodiment, which is composed of active material retention members 11 all formed of the first cylindrical member 12A, adjacent cylindrical members 12 in the active material retention member 11 are in contact with each other via the protrusions 71. 5, the protrusions 71, 71 of adjacent cylindrical members 12, 12 do not overlap each other, and a gap G (G=T) that matches the protrusion height T of the protrusions 71 described above is formed between the adjacent cylindrical members 12, 12. Note that the protrusions 71, 71 of adjacent cylindrical members 12, 12 may overlap each other, and a gap G (G=2T) that matches twice the protrusion height T of the protrusions 71 described above may be formed between the adjacent cylindrical members 12, 12.

[0031] 2, the active material holding member 11 is sandwiched between separators 30, 30 in the Y-axis direction. The multiple tubular members 12 constituting the active material holding member 11 are arranged in contact with the separators 30. The electrode group 110 is housed in a battery case 120 having a relatively narrow space, so that the active material holding member 11 is sandwiched between the separators 30 in a pressed state.

[0032] As shown in Fig. 6, the cylindrical member 12 and separator 30 that constitute the positive electrode 10 are in contact with each other via a protruding portion 71. In the active material holding member 11 that is entirely composed of the first cylindrical member 12A, a gap G2 is formed between the cylindrical member 12 and the separator 30. The size of the gap G2 is equal to the protruding height T of the protruding portion 71 described above. Note that, if a protruding portion (rib) is formed on the outer surface facing outward, the protruding portion 71 and the protruding portion (rib) may be arranged to be in contact with each other.

[0033] The substrate 13 forming the tubular member 12 may be formed to include nonwoven fabric, woven fabric, etc., and is formed to include nonwoven fabric, for example. The substrate 13 can contain a resin material. Examples of resin materials include polyester (e.g., polyalkylene terephthalate such as polyethylene terephthalate), polyolefin (polyethylene, polypropylene, etc.), polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinylidene fluoride, polycarbonate, etc. The substrate can contain, for example, polyester, and can include nonwoven fabric containing polyester.

[0034] When the substrate 13 contains fibers, the fibers may be oriented. For example, a nonwoven fabric may have an MD (machine direction) in the production of the nonwoven fabric and a CD (cross direction) perpendicular to the MD. Because fibers tend to be oriented in the MD direction, the mechanical strength in the MD direction tends to be higher than that in the CD direction. Therefore, a resin sheet with high mechanical strength in the CD direction also has high mechanical strength in the direction (CD direction) where the mechanical strength is relatively low. When the substrate 13 contains a nonwoven fabric, it is preferable that the MD and CD directions of the nonwoven fabric are inclined with respect to the axial direction (Z-axis direction) of the tubular member 12 in at least one of the active material holding members 11, from the viewpoint of easily suppressing the influence of the mechanical strength due to the fiber orientation and thus easily suppressing leakage of the active material.

[0035] The inclination angle of the MD or CD direction with respect to the axial direction of the cylindrical member 12 is preferably in the following range, from the viewpoint of easily suppressing the influence of fiber orientation on mechanical strength and thus easily suppressing leakage of active material. The inclination angle is preferably greater than 0°, more preferably 10° or greater, even more preferably 20° or greater, particularly preferably 30° or greater, extremely preferably 40° or greater, and very preferably 43° or greater. The inclination angle is preferably less than 90°, more preferably 80° or less, even more preferably 70° or less, particularly preferably 60° or less, extremely preferably 50° or less, and extremely preferably 47° or less. From these viewpoints, the inclination angle is preferably greater than 0° and less than 90°, more preferably 10° to 80°, and even more preferably 43° to 47°. It is estimated that an inclination angle of 45° is most likely to suppress the influence of fiber orientation on mechanical strength.

[0036] The substrate 13 may be a porous body having pores. The substrate 13 preferably has a portion having an average pore diameter in the following range. From the viewpoint of easily suppressing the outflow of the electrode material, the average pore diameter of the substrate 13 is preferably 60 μm or less, more preferably 50 μm or less, even more preferably 45 μm or less, and particularly preferably 40 μm or less. From the viewpoint of easily reducing electrical resistance, the average pore diameter of the substrate 13 is preferably greater than 2 μm, more preferably 5 μm or more, even more preferably 10 μm or more, particularly preferably 20 μm or more, extremely preferably 30 μm or more, and very preferably 35 μm or more. From these viewpoints, the average pore diameter of the substrate 13 is preferably greater than 2 μm and less than 60 μm. The average pore diameter can be measured using a pore size distribution measuring device (e.g., AUTO PORE IV 9520, manufactured by Shimadzu Corporation).

[0037] At least one cylindrical member 12 in the active material holding member 11 may have a portion having a thickness T0 (also referred to as the wall thickness or the thickness of the wall portion constituting the cylindrical member 12. The thickness T0 is the thickness of the substrate 13. The same applies below) within the following range. The thickness T0 of the cylindrical member 12 may be within the following range. The thickness T0 of the cylindrical member 12 may be 0.05 mm or more, 0.1 mm or more, or 0.2 mm or more. The thickness T0 of the cylindrical member 12 may be 1 mm or less, 0.8 mm or less, 0.6 mm or less, or 0.4 mm or less. From these perspectives, the thickness T0 of the cylindrical member 12 may be 0.05 mm to 1 mm.

[0038] The length of at least one cylindrical member 12 in the active material holding member 11 may be within the following ranges. The length of the cylindrical member 12 may be 50 mm or more, 100 mm or more, 120 mm or more, 160 mm or more, or 200 mm or more. The length of the cylindrical member 12 may be 800 mm or less, 750 mm or less, 700 mm or less, 650 mm or less, 600 mm or less, or 580 mm or less. From these perspectives, the length of the cylindrical member 12 may be 50 mm to 800 mm.

[0039] The core metal 14 is inserted into each cylindrical member 12. The core metal 14 is formed in a rod shape. The core metal 14 extends along the Z-axis direction inside the cylindrical member 12. The core metal 14 can be obtained by, for example, casting (pressure casting). The constituent material of the core metal 14 may be any conductive material, and examples thereof include lead alloys such as lead-calcium-tin alloys and lead-antimony-arsenic alloys. The lead alloy may contain selenium, silver, bismuth, etc. The length of the core metal 14 is, for example, 45 mm to 805 mm.

[0040] The cathode material 16 is filled inside the cylindrical member 12. The cathode material 16 includes an active material. The active material includes both a chemically converted active material and raw materials for the active material before chemical conversion. The cathode material 16 here includes the chemically converted active material. The chemically converted cathode material 16 can be obtained, for example, by chemically converting an unchemically converted cathode material 16 containing raw materials for the cathode active material. The chemically converted cathode material 16 can be obtained, for example, by aging and drying a cathode material paste containing raw materials for the cathode active material to obtain the unchemically converted cathode material 16, and then chemically converting the unchemically converted cathode material 16. Examples of raw materials for the cathode active material include lead powder and red lead. Examples of the cathode active material in the chemically converted cathode material 16 include lead dioxide. The cathode material 16 may further contain additives as needed. Examples of additives for the cathode material 16 include short reinforcing fibers. Examples of reinforcing short fibers include acrylic fibers, polyethylene fibers, polypropylene fibers, polyethylene terephthalate fibers (PET fibers), and the like.

[0041] The cylindrical member 12, the metal core 14, and the positive electrode material 16 constitute a cylindrical electrode. The cylindrical electrode of the positive electrode 10 is electrically connected to the electrode post 140a via the connecting portion 18a, the lug portion 18b, and the connecting member 130a.

[0042] As shown in FIG. 1 , the lower connecting seat 51 is attached to a first end 13a, which is the lower end of the plurality of cylindrical members 12 that constitute the active material holding member 11. The lower connecting seat 51 seals the lower ends of the plurality of cylindrical members 12. The lower connecting seat 51 is fitted to the lower ends of the plurality of cylindrical members 12. The first end 13a, which is the lower end of the cylindrical members 12, may be welded by melting a resin, which will be described in detail later in the process of forming the lower connecting seat 51. Alternatively, the lower connecting seat 51 may be integrally formed with the cylindrical members 12 when injection molding.

[0043] The lower linking seat 51 is formed of, for example, an acid-resistant material. Examples of materials for the lower linking seat 51 include resins such as polyolefin (polypropylene, polyethylene, etc.), polyethylene terephthalate (PET), polystyrene (PS), polyvinylidene fluoride (PVDF), and polycarbonate (PC). From the viewpoint of easily improving cycle characteristics, the lower linking seat 51 preferably contains a thermoplastic resin, more preferably contains a polyolefin, and even more preferably contains polypropylene. From the viewpoint of easily improving cycle characteristics, when the cylindrical member 12 contains a polyolefin, the lower linking seat 51 preferably contains the same material. The lower linking seat 51 may be formed of the same material as the cylindrical member 12, or may be formed of a different material from the cylindrical member 12. The material for the lower linking seat 51 is not particularly limited.

[0044] As shown in FIG. 1 , the upper linking seat 61 is attached to the second end portion 13b, which is the upper end portion of the plurality of cylindrical members 12 constituting the active material holding member 11. The upper linking seat 61 is fixed to the upper end portion of the cylindrical member 12 by welding. When welding, the boundary portion between the upper linking seat 61 and the cylindrical member 12 and the upper linking seat 61 may be integrated. Welding can be achieved by heating, ultrasonic irradiation, laser irradiation, or the like. The upper linking seat 61 may also be fixed to the upper end portions of the plurality of cylindrical members 12 by a thermosetting adhesive or the like.

[0045] The upper linking seat 61 is formed of a material containing, for example, polystyrene. The material of the upper linking seat 61 is not particularly limited. For example, examples of materials for the upper linking seat 61 include acid-resistant materials. Examples of materials for the upper linking seat 61 include resins such as polyolefin (polypropylene, polyethylene, etc.), polyethylene terephthalate (PET), polystyrene (PS), polyvinylidene fluoride (PVDF), and polycarbonate (PC).

[0046] The negative electrode 20 is, for example, a plate-shaped electrode. The negative electrode 20 is, for example, a paste-type negative electrode plate. The negative electrode 20 is electrically connected to the electrode post 140b via a connecting member 130b. The negative electrode 20 has a negative electrode current collector and a negative electrode material, which is an electrode material held by the negative electrode current collector. A plate-shaped current collector can be used as the negative electrode current collector. The compositions of the negative electrode current collector and the core metal 14 of the positive electrode 10 may be the same or different. The negative electrode material contains an active material. The negative electrode material here contains the active material after chemical conversion.

[0047] The chemically formed negative electrode material can be obtained, for example, by chemically forming an unformed negative electrode material containing raw materials for the negative electrode active material. The chemically formed negative electrode material can be obtained, for example, by aging and drying a negative electrode material paste containing raw materials for the negative electrode active material to obtain an unformed negative electrode material, and then chemically forming the unformed negative electrode material. Examples of raw materials for the negative electrode active material include lead powder. Examples of negative electrode active materials in the chemically formed negative electrode material include porous spongy lead. The negative electrode material may further contain additives as needed. Examples of additives for the negative electrode material include barium sulfate, reinforcing short fibers, carbon materials (carbonaceous conductive materials), and resins having at least one selected from the group consisting of sulfonic groups and sulfonate groups (resins having sulfonic groups and / or sulfonate groups). The reinforcing short fibers can be the same as those used for the positive electrode material.

[0048] Examples of carbon materials include carbon black, graphite, etc. Examples of carbon black include furnace black (such as Ketjen Black (registered trademark)), channel black, acetylene black, thermal black, etc. Examples of resins having sulfonic groups and / or sulfonate groups include lignin sulfonic acid, lignin sulfonate salts, condensates of phenols, aminoarylsulfonic acid, and formaldehyde, etc. Examples of lignin sulfonate salts include alkali metal salts of lignin sulfonic acid, etc. Examples of phenols include bisphenol-based compounds such as bisphenol, etc. Examples of aminoarylsulfonic acids include aminobenzenesulfonic acid, aminonaphthalenesulfonic acid, etc.

[0049] The support member 160 is disposed on the bottom surface of the battery case 120 and supports the lower linking seat 51. The support member 160 has multiple ridges 160a that protrude in the Z-axis direction. The ridges 160a are provided on the bottom surface of the battery case 120. The ridges 160a extend in the X-axis direction. The ridges 160a are aligned in the Y-axis direction. The ridges 160a abut against the lower linking seat 51. In other words, the support member 160 supports the portion of the lower linking seat 51 that faces the bottom surface of the battery case 120 with each ridge 160a. The ridges 160a only need to be in contact with the positive electrode 10, and do not have to be in contact with the negative electrode 20.

[0050] The effects of the lead-acid battery 100 including the active material retention member 11 of the above embodiment will be described. In the positive electrode 10 of the lead-acid battery 100 of the above embodiment, at least one of the tubular members 12 of the active material retention member 11 constituting the positive electrode 10 is the first tubular member 12A or the second tubular member 12B, and the tubular member 12 is in contact with the separator 30 via the protrusion 71. As a result, the outer surface of the tubular member 12 of the active material retention member 11 does not come into contact with the separator 30, and a gap G is formed between the tubular member 12 and the separator 30. As a result, the short-circuit resistance between the positive electrode 10 made of the active material retention member 11 and the separator 30 can be improved.

[0051] In the positive electrode 10 of the lead-acid battery 100 of the above embodiment, the cylindrical member 12 (first cylindrical member 12A) is formed so that the entire welded portion 70 extending spirally from the first end 13a to the second end 13b becomes the protruding portion 71. As a result, when forming an active material holding member 11 in which the cylindrical members 12 are arranged in the X direction (second direction), it is sufficient to arrange the cylindrical members 12 without considering the direction in which the protruding portion 71 is formed (i.e., without considering whether the protruding portion 71 faces the separator 30), thereby improving production efficiency.

[0052] In the positive electrode 10 of the lead-acid battery 100 of the above embodiment, the protrusion 71 is formed so that the protrusion height from the outer surface of the substrate 13 is 1.02 to 2.00 times the thickness T0 of the substrate 13. This makes it possible to more reliably improve the short-circuit resistance between the separator 30 and the positive electrode 10 made of the active material holding member 11.

[0053] In the positive electrode 10 of the lead-acid battery 100 of the above embodiment, the protrusion 71 is formed so that its density is 1.4 to 5.0 times the density of the substrate 13. This can increase the durability of the protrusion 71, which is the portion that comes into contact with the separator 30.

[0054] In the positive electrode 10 of the lead-acid battery 100 of the above embodiment, the plurality of cylindrical members 12 constituting the active material holding member 11 are all first cylindrical members 12A formed by spirally winding a strip-shaped base material 13 from a first end 13a to a second end 13b and welding a longitudinal end 13c of the base material 13 (see FIG. 4). This allows only the above-described first cylindrical members 12A to be prepared when forming the active material holding member 11, thereby improving productivity.

[0055] Although one embodiment has been described above, one aspect of the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of one aspect of the present invention.

[0056] <Variation 1> In the above embodiment, an example in which the active material retention member 11 is formed solely from a first cylindrical member 12A as shown in FIG. 4 has been described, but the present invention is not limited thereto. For example, the active material retention member 11 may be formed from the above-described first cylindrical member 12A and a cylindrical member 12 having a flat shape and no protrusions 71 on the outer peripheral surface of the substrate 13 (hereinafter, such a cylindrical member 12 is referred to as a "third cylindrical member 12C"). Even in this case, by incorporating an appropriate number of first cylindrical members 12A among the multiple cylindrical members 12 (for example, the area of ​​all protrusions 71 per surface area of ​​one side of the positive electrode 10 formed by the multiple cylindrical members 12 is 8% to 33%), a gap G is formed between the cylindrical member 12 and the separator 30. As a result, the short-circuit resistance between the positive electrode 10 formed from the active material retention member 11 and the separator 30 can be improved.

[0057] Furthermore, when the active material holding member 11 is configured with a first cylindrical member 12A and a third cylindrical member 12C, at least one first cylindrical member 12A may be disposed on each of one end side R and the other end side L in the X direction (second direction) from the center position of the active material holding member 11 in the X direction (second direction), as shown in Fig. 8(A). In the example shown in Fig. 8(A), the first cylindrical members 12A, 12A are disposed at both ends in the X direction. This allows the active material holding member 11 and the separator 30 to be stably disposed when they are placed in contact with each other in the battery container 120 with the protrusion 71 of the cylindrical member 12 interposed therebetween. <Variation 2> In place of the first cylindrical member 12A constituting the active material holding member 11 in the above embodiment and modified examples, a second cylindrical member 12B as shown in Figures 7(A) and 7(B) may be applied, which is formed by welding the end portion 13d of the base material 13 when the base material 13 is wound around once, as shown in Figure 3(B).

[0058] More specifically, the substrate 13 constituting the second tubular member 12B is wound in a spiral shape as shown in FIG. 3(B). When the substrate 13 is wound in a spiral shape, for example, the second tubular member 12B can be formed by winding a rectangular substrate 13 along one side of the substrate 13. "Spiral" means to wind around in the same plane. For example, in the case of a spiral shape, the tubular member 12 elongates as the substrate 13 is wound, whereas in the case of a spiral shape, the tubular member 12 thickens as the substrate 13 is wound, but the tubular member 12 does not elongate. In the case of a spiral shape, the winding direction refers to the direction of rotation of the substrate 13 relative to the central axis. In the case of a spiral shape, the winding direction refers to the direction in which the substrate 13 is wound from the inner layer to the outer layer of the tubular member 12.

[0059] 8(B), even in the case of a positive electrode 10 constituted by an active material holding member 11 according to such a modified example, by orienting the protruding direction of the protrusion 71 in the Y direction (i.e., the direction facing the separator 30), a gap G is formed without direct contact between the outer surface of the tubular member 12 constituting the active material holding member 11 and the separator 30. As a result, the short-circuit resistance between the positive electrode 10 constituted by the active material holding member 11 and the separator 30 can be improved.

[0060] <Other variations> In the positive electrode 10 of the lead-acid battery 100 of the above-described embodiment and modified example, at least one of the adjacent cylindrical members 12, 12 in the active material holding member 11 is the first cylindrical member 12A and is in contact with each other via the protrusion 71. However, this is not limiting. For example, at least one of the adjacent cylindrical members 12, 12 in the active material holding member 11 may be the first cylindrical member 12A (see FIG. 4(A)) or the second cylindrical member 12B (see FIG. 7(B)). Although the protrusion 71 of the first cylindrical member 12A or the second cylindrical member 12B protrudes in the direction along which the adjacent cylindrical members 12, 12 face each other, the adjacent cylindrical members 12, 12 do not necessarily have to be in contact with each other. In this configuration, even if the adjacent cylindrical members 12, 12 come into contact with each other, the contact is always via the protrusion 71. That is, even if the cylindrical members 12, 12 come into contact with each other, the outer surfaces do not come into contact with each other, and a gap G is formed between the cylindrical members 12, 12. As a result, the fluidity of the electrolyte can be increased during gassing.

[0061] In the lead-acid battery 100 of the above embodiment and modified example, the cylindrical member 12 constituting the positive electrode 10 and the separator 30 are in contact with each other via the protruding portion 71. However, the present invention is not limited to this. For example, the protruding portion 71 of the cylindrical member 12 constituting the positive electrode 10 may protrude in the direction in which the separator 30 is disposed without contacting the separator 30.

[0062] The cylindrical member 12 in the above embodiment and modified example has been described using an example in which the cross section of the outer shape when viewed from the extension direction is formed to be circular, but as long as it is cylindrical, it may be elliptical, rectangular, diamond-shaped, square, etc.

[0063] The active material holding member 11, the electrode group 110, and the lead-acid battery 100 according to one embodiment of the present invention can be used in, for example, an electric vehicle. Examples of the electric vehicle include a forklift and a golf cart.

[0064] In one aspect of the present invention, the configurations of the above-described embodiment and the above-described modified examples may be combined as appropriate. [Explanation of symbols]

[0065] 10...positive electrode, 11...active material holding member, 12...cylindrical member, 12A...first cylindrical member, 12B...second cylindrical member, 12C...third cylindrical member, 13...substrate, 13a...first end, 13b...second end, 13c...longitudinal end, 13d...side end, 16...positive electrode material (active material), 20...negative electrode, 30...separator, 40...electrolyte, 70...welded portion, 71...protrusion, 100...lead-acid battery, 110...electrode group, 120...battery case

Claims

1. A lead-acid battery comprising: an active material retention member in which cylindrical members extending in a first direction between a first end and a second end are arranged in a second direction perpendicular to the first direction; and an active material filled in the cylindrical members; and an electrode group in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween, the cylindrical members constituting the active material holding member include at least one of a first cylindrical member formed by welding longitudinal ends of a strip-shaped substrate when the substrate is spirally wound from the first end toward the second end, and a second cylindrical member formed by welding a winding end of the substrate when the substrate is wound once around, At least a part of the welded portions of the first cylindrical member and the second cylindrical member protrudes outward from an outer surface of the base material, and a protrusion having a density higher than a density of the base material is formed, at least one of the cylindrical members of the active material holding member constituting the positive electrode is the first cylindrical member or the second cylindrical member, and the protruding portion of the cylindrical member protrudes in a direction in which the separator is disposed; the cylindrical member constituting the positive electrode and the separator are in contact with each other via the protrusion, and an outer surface of the cylindrical member constituting the positive electrode and the separator are not in contact with each other.

2. A lead-acid battery as described in claim 1, wherein at least one of the adjacent tubular members in the active material holding member is the first tubular member or the second tubular member, and they are in contact with each other via the protrusion, and the outer surfaces of the tubular members are not in contact with each other.

3. The lead-acid battery according to claim 1 or 2, wherein the protrusion is formed so that the protrusion height from the outer surface of the base is 1.02 to 2.0 times the thickness of the base.

4. The lead acid battery according to any one of claims 1 to 3, wherein the protrusion is formed so that its density is 1.4 to 5.0 times the density of the substrate.

5. The first cylindrical member is formed so that all of the welded portion extending spirally from the first end to the second end becomes the protrusion. The lead acid battery according to any one of claims 1 to 4.

6. The lead-acid battery according to any one of claims 1 to 5, wherein all of the plurality of cylindrical members constituting the active material holding member are the first cylindrical members.

7. At least one of the first cylindrical member or the second cylindrical member is arranged on one end side and the other end side in the second direction from the center position in the second direction of the active material holding member. The lead acid battery according to any one of claims 1 to 6.

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