JP7523452B2 - Electrode, lead-acid battery, current collector, and method for manufacturing current collector - Google Patents

Description

One aspect of the present invention relates to electrodes, lead-acid batteries, current collectors and methods for manufacturing current collectors.

Lead-acid batteries are widely used as secondary batteries for industrial and consumer use, and there is particularly high demand for them as lead-acid batteries (so-called batteries) for electric vehicles, and as backup lead-acid batteries for UPS (Uninterruptible Power Supply), disaster prevention (emergency) radios, telephones, etc.

The lead-acid battery comprises an electrode group including a plurality of electrodes, and a battery case that contains the electrode group. The electrode comprises a cylindrical body, a rod-shaped current collector (core metal) inserted into the cylindrical body, an electrode material including an active material filled inside the cylindrical body, and a sealing member (lower seat) that seals one end of the cylindrical body (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 61-232572

In the above-mentioned electrodes, one end of the rod-shaped current collector may be fitted into the sealing member. In such cases, it is necessary to improve the fit between the sealing member and the current collector, for example, taking into account use in various environments.

One aspect of the present invention aims to provide an electrode and a lead-acid battery that can improve the fit between a sealing member and a current collector.

An electrode according to one aspect of the present invention comprises a cylindrical body, a rod-shaped current collector inserted into the cylindrical body, an electrode material containing an active material filled inside the cylindrical body, and a sealing member that seals one end of the cylindrical body, the sealing member having a cylindrical main body into which one end of the current collector is fitted, the end face of the one end side of the current collector having an elongated shape with a longitudinal direction, and one and the other longitudinal sides of the elongated shape at one end of the current collector are recessed into the inner surface of the cylindrical hole of the main body.

In this electrode, the end face on one end side of the current collector has an elongated shape. One side and the other side of the elongated shape of one end of the current collector are embedded into the inner surface of the tubular hole of the main body part. This allows the one end of the current collector to be firmly fitted into the tubular hole of the main body part. This makes it possible to improve the fit between the sealing member and the current collector.

In an electrode according to one aspect of the present invention, the cylindrical hole of the main body portion may include a circular hole, and the long shape of the current collector may be an oval shape, a flattened circular shape, or an elliptical shape having a major axis larger than the diameter of the cylindrical hole as a circular hole. With this configuration, one end of the current collector can be effectively embedded into the inner surface of the cylindrical hole, effectively improving the fit between the sealing member and the current collector.

In an electrode according to one aspect of the present invention, at least the other end of the current collector may have a circular cross section. In this case, even if corrosion of the current collector progresses, at least the other end of the current collector is less likely to form a locally thin portion. This makes it possible to suppress breakage of the current collector. Also in this case, the active material is more likely to be used evenly inside the cylindrical body, at least around the other end of the current collector. This makes it possible to improve current collection properties.

In one aspect of the electrode of the present invention, the cylindrical body may have a cylindrical shape. In this case, the active material is more likely to be used evenly inside the cylindrical body, which makes it possible to improve current collection.

In an electrode according to one aspect of the present invention, when viewed from the axial direction of the tubular hole, a protruding portion that protrudes from the inner surface may be provided on one side, the other side, or both sides in the short side direction of the elongated shape of the current collector inserted in the tubular hole on the inner surface of the tubular hole. In this case, the protruding portion makes it possible to prevent the formation of a gap between the current collector and the inner surface of the tubular hole in the short side direction.

A lead-acid battery according to one aspect of the present invention is provided with the above-mentioned electrodes. This lead-acid battery also has the above-mentioned effect of improving the fit between the sealing member and the current collector.

The current collector according to one aspect of the present invention is a rod-shaped current collector inserted into a cylindrical body in an electrode comprising an electrode material containing an active material filled inside the cylindrical body, and a sealing member that seals one end of the cylindrical body, and the end face on the one end side has an elongated shape with a longitudinal direction. With this current collector, for example, when one end is fitted into the sealing member, it is possible to firmly fit the one end into the sealing member by embedding one side and the other side of the longitudinal direction of the elongated shape of the one end into the sealing member. This makes it possible to improve the fit between the sealing member and the current collector.

In the current collector according to one aspect of the present invention, the elongated shape may be an oval shape, a flattened circular shape, or an elliptical shape. In this case, for example, when one end of the current collector is fitted into a sealing member, the one end can be effectively embedded into the sealing member, and it is possible to effectively improve the fit between the sealing member and the current collector.

In the current collector according to one aspect of the present invention, at least the other end may have a circular cross section. In this case, even if corrosion of the current collector progresses, at least the other end of the current collector is less likely to form a locally thin portion. This makes it possible to suppress breakage of the current collector. Also, in this case, the active material is more likely to be used evenly inside the cylindrical body, at least around the other end of the current collector. This makes it possible to improve current collection properties.

A method for producing a current collector according to one aspect of the present invention is a method for producing the current collector, and includes a cutting step of cutting a rod-shaped member constituting the current collector, and a shaping step of shaping an end face on one end side of the cut rod-shaped member so as to have an elongated shape. With a current collector produced by this manufacturing method, it is possible to firmly fit one end of the current collector into a sealing member, and it is possible to improve the fit between the sealing member and the current collector.

In the method for producing a current collector according to one aspect of the present invention, the forming step may form the end face on one end side of the rod-shaped member by utilizing the force required for cutting the rod-shaped member in the cutting step. In this case, the elongated shape of the end face on one end side of the current collector can be easily and efficiently realized.

According to one aspect of the present invention, it is possible to provide an electrode, a lead-acid battery, a current collector, and a method for manufacturing a current collector that can improve the fit between a sealing member and a current collector.

FIG. 1 is a cross-sectional view that illustrates a lead-acid battery according to an embodiment. FIG. 2 is a partial cross-sectional view taken along line II-II in FIG. FIG. 3 is a perspective view showing the positive electrode of FIG. Fig. 4(a) is a plan view showing the upper linkage of Fig. 1. Fig. 4(b) is a front view showing the upper linkage of Fig. 1. FIG. 5 is a partial cross-sectional view taken along line VV in FIG. FIG. 6 is a front view showing the lower linkage of FIG. FIG. 7 is a partial cross-sectional view taken along line VII-VII in FIG. FIG. 7 is a partial plan view of the lower link seat of FIG. 9 is a front view showing the core, the connecting portion, and the lug portion of the positive electrode of FIG. Fig. 10(a) is a diagram showing an end face on the lower end side of the core metal in the positive electrode of Fig. 3. Fig. 10(b) is a partial cross-sectional view taken along line Xb-Xb in Fig. 9. Fig. 10(c) is a partial cross-sectional view taken along line Xc-Xc in Fig. 1. Fig. 11(a) is a view showing an end face on the lower end side of a core bar according to a first modified example. Fig. 11(b) is a view showing an end face on the lower end side of a core bar according to a second modified example. Fig. 11(c) is a view showing an end face on the lower end side of a core bar according to a third modified example. Fig. 11(d) is a view showing an end face on the lower end side of a core bar according to a fourth modified example. Fig. 11(e) is a view showing an end face on the lower end side of a core bar according to a fifth modified example.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, identical or equivalent elements are given the same reference numerals, and duplicate explanations will be omitted. The size of the components in each drawing is conceptual, and the relative relationship of the size between the components is not limited to that shown in each drawing.

Figure 1 is a cross-sectional view showing a schematic diagram of a lead-acid battery. Figure 2 is a partial cross-sectional view taken along line II-II in Figure 1. Figure 3 is a perspective view showing a positive electrode. In Figure 1, positive electrodes and negative electrodes are alternately arranged with separators between them from the front to the back of the drawing. Figure 1 shows a cross-sectional view of a portion of the positive electrode. Figure 2 shows the laminated structure of the positive electrode, negative electrode, and separator when the lead-acid battery is viewed from above. The terms "upper" and "lower" correspond to the upper and lower sides in the height direction of the battery case (the same applies below). The Z direction corresponds to the height direction of the battery case, the X direction corresponds to the direction perpendicular to the Z direction, and the Y direction corresponds to the direction perpendicular to both the Z direction and the X direction.

As shown in Figures 1 and 2, the lead-acid battery 100 of the embodiment includes an electrode group 110, a battery case 120 that houses the electrode group 110, connecting members 130a, 130b connected to the electrode group 110, poles 140a, 140b connected to the connecting members 130a, 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.

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 the negative electrodes 20 are alternately arranged in the X direction via the separators 30. The space around the positive electrodes 10 between the separators 30 is filled with an electrolyte 40. 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 40 to pass through. Examples of materials for the separator 30 include a mixture of microporous polyethylene, glass fiber, and synthetic resin.

1, 2, and 3, the positive electrode 10 is, for example, a plate-shaped electrode. The positive electrode 10 has a plurality of cylindrical bodies 12a, a plurality of core metals (current collectors) 14, a positive electrode material (electrode material) 16, a lower connecting seat (sealing member) 51, an upper connecting seat 1, a connecting portion 12e, and an ear portion 12d.

The multiple cylindrical bodies 12a are arranged in a row adjacent to each other along the Y direction. The multiple cylindrical bodies 12a constitute a group of tubes (clad tubes) for holding active material. The group of tubes for holding active material is also called a "gauntlet". The cylindrical bodies 12a extend in the Z direction. The structure in which the multiple cylindrical bodies 12a are arranged in a row may be obtained by the cylindrical bodies 12a being separate from each other, or may be obtained by forming multiple through holes between the substrates facing each other. A connection part such as a seam (seamed part) may be arranged between the adjacent cylindrical bodies 12a.

The cylindrical body 12a has a cylindrical shape. The cylindrical body 12a may have an elliptical cylindrical shape, a square cylindrical shape (e.g., a square cylindrical shape with rounded corners), or the like. The length of the cylindrical body 12a is, for example, 160 to 400 mm. The diameter of the cylindrical body 12a may be, for example, 5 mm or more. The diameter of the cylindrical body 12a may be, for example, 12 mm or less. The thickness of the cylindrical body 12a may be, for example, 100 μm or more. The thickness of the cylindrical body 12a may be, for example, 2000 μm or less.

The cylindrical body 12a is formed of a porous body. The cylindrical body 12a may be formed of a base material such as a woven fabric or a nonwoven fabric. An acid-resistant material can be used as the base material. Examples of the base material include resins such as polyolefin (polypropylene, polyethylene, etc.), polyethylene terephthalate (PET), polystyrene (PS), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polyvinylidene fluoride (PVDF), and polycarbonate (PC), and inorganic materials such as glass fiber, silicon carbide, and alumina. From the viewpoint of easily improving cycle characteristics, the cylindrical body 12a preferably contains a thermoplastic resin, and more preferably contains a polyolefin.

In the cylindrical body 12a, a resin may be held on the substrate. Examples of the resin include acrylic resin, epoxy resin, phenolic resin, melamine resin, and styrene resin. The resin may be held on the inner or outer surface of the substrate, or on the surface of the pores in the substrate, or may be attached to the substrate. The resin may be held on a part of the substrate, or on the entire substrate.

The core metal 14 is inserted into each cylindrical body 12a. The core metal 14 is rod-shaped. The core metal 14 extends along the Z direction inside the cylindrical body 12a. The core metal 14 can be obtained, for example, by casting (pressure casting). The constituent material of the core metal 14 may be any conductive material, such as a lead alloy such as a lead-calcium-tin alloy or a lead-antimony-arsenic alloy. The lead alloy may contain selenium, silver, bismuth, etc. The length of the core metal 14 is, for example, 170 to 400 mm.

The positive electrode material 16 is filled inside the cylindrical body 12a. The positive electrode material 16 includes an active material. The active material includes both the active material after chemical conversion and the raw material of the active material before chemical conversion. The positive electrode material 16 here contains the active material after chemical conversion. The positive electrode material 16 after chemical conversion can be obtained, for example, by chemical conversion of the unchemical positive electrode material 16 containing the raw material of the positive electrode active material. The positive electrode material 16 after chemical conversion can be obtained, for example, by aging and drying a positive electrode material paste containing the raw material of the positive electrode active material to obtain the unchemical positive electrode material 16, and then chemical conversion of the unchemical positive electrode material 16. Examples of the raw material of the positive electrode active material include lead powder and red lead. Examples of the positive electrode active material in the positive electrode material 16 after chemical conversion include lead dioxide. The positive electrode material 16 may further contain an additive as necessary. Examples of the additive of the positive electrode material 16 include short fibers for reinforcement. Examples of reinforcing short fibers include acrylic fibers, polyethylene fibers, polypropylene fibers, and polyethylene terephthalate fibers (PET fibers).

The cylindrical body 12a, the metal core 14, and the positive electrode material 16 constitute a cylindrical electrode (rod-shaped electrode). The cylindrical electrode of the positive electrode 10 is electrically connected to the pole 140a via the connecting portion 12e, the ear portion 12d, and the connecting member 130a.

The lower linking seat 51 is attached to the lower ends of the multiple cylindrical bodies 12a. The lower ends of the cylindrical bodies 12a are the terminal portion (one end) of one end of the cylindrical bodies 12a, in other words, the end of the cylindrical bodies 12a on the bottom side of the battery case 120. The lower linking seat 51 seals the lower ends of the multiple cylindrical bodies 12a. The lower linking seat 51 is fitted into the lower ends of the multiple cylindrical bodies 12a. The lower linking seat 51 may be fixed to the lower ends of the multiple cylindrical bodies 12a by a thermosetting adhesive or the like.

The upper linking seat 1 is attached to the upper end of the cylindrical body 12a. The upper end of the cylindrical body 12a is the terminal portion (other end) of the other end side of the cylindrical body 12a, in other words, the end of the cylindrical body 12a on the top side of the battery case 120. The upper linking seat 1 is fixed to the upper end of the cylindrical body 12a by welding. In welding, the boundary portion between the upper linking seat 1 and the cylindrical body 12a and the upper linking seat 1 may be integrated. Welding can be achieved by heating, ultrasonic irradiation, laser irradiation, etc. The upper linking seat 1 may be fixed to the upper end of multiple cylindrical bodies 12a by a thermosetting adhesive or the like.

1 and 2, 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 column 140b via a connecting member 130b. The negative electrode 20 has a negative electrode collector and a negative electrode material, which is an electrode material held by the negative electrode collector. A plate-shaped collector can be used as the negative electrode collector. The compositions of the negative electrode collector and the core metal 14 of the positive electrode 10 may be the same or different from each other. The negative electrode material contains an active material. The negative electrode material here contains the active material after chemical formation.

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

Examples of carbon materials include carbon black and graphite. Examples of carbon black include furnace black (Ketjen Black (registered trademark), etc.), 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. Examples of aminoarylsulfonic acids include aminobenzenesulfonic acid, aminonaphthalenesulfonic acid, etc.

The support member 160 is disposed on the bottom surface of the battery case 120 and supports the lower connecting seat 51. The support member 160 has a plurality of protrusions 160a extending in the Z direction. The protrusions 160a are provided on the bottom surface of the battery case 120. The protrusions 160a extend in the X direction. The protrusions 160a are aligned in the Y direction. The protrusions 160a abut against the lower connecting seat 51 (see FIG. 1). That is, the support member 160 supports the portion of the lower connecting seat 51 on the bottom side of the battery case 120 with each protrusion 160a. The protrusions 160a need only be in contact with the positive electrode 10, and do not need to be in contact with the negative electrode 20.

Figure 4(a) is a plan view showing the upper linking seat 1. Figure 4(b) is a front view showing the upper linking seat 1. Figure 5 is a partial cross-sectional view taken along line V-V in Figure 4(a). As shown in Figures 4(a), 4(b) and 5, the upper linking seat 1 includes a bottomed box-shaped base 2 having an elongated opening 2a, and a plurality of tubular portions 3 provided on the bottom surface 2b of the base 2.

The base 2 abuts against the upper end of the cylindrical body 12a. A predetermined number of cylindrical portions 3 are provided corresponding to the number of cylindrical bodies 12a. The cylindrical portions 3 are cylindrical with an outer diameter corresponding to the inner diameter of the cylindrical bodies 12a. The cylindrical portions 3 are inserted so as to communicate with each of the upper ends of the cylindrical bodies 12a. The cylindrical holes 3a of the cylindrical portions 3 communicate with the inside of the base 2.

The upper linking seat 1 is formed of a material including, for example, polystyrene. The material of the upper linking seat 1 is not particularly limited. For example, an acid-resistant material can be used as the material of the upper linking seat 1. Examples of materials for the upper linking seat 1 include resins such as polyolefin (polypropylene, polyethylene, etc.), polyethylene terephthalate (PET), polystyrene (PS), polyvinylidene fluoride (PVDF), and polycarbonate (PC).

Figure 6 is a front view showing the lower linking seat 51. Figure 7 is a partial cross-sectional view taken along line VII-VII in Figure 6. Figure 8 is a plan view showing a portion of the lower linking seat 51. The lower linking seat 51 fits onto the ends of a plurality of cylindrical bodies 12a. As shown in Figures 6, 7 and 8, the lower linking seat 51 comprises a plurality of main body portions 52, protruding pieces 53 provided on each of the plurality of main body portions 52, and a connecting portion 54 connecting the plurality of main body portions 52.

A portion of the main body 52 is fitted (inserted and fitted) into the lower end of the cylindrical body 12a. The main body 52 has a bottomed cylindrical shape with the Z direction as its axial direction and opening upward. The lower end (one end) of the core 14 is fitted into the cylindrical hole 52h of the main body 52. This allows the core 14 to be held in the cylindrical hole 52h. The cylindrical hole 52h of the main body 52 includes a circular hole. The circular hole of the cylindrical hole 52h here is a hole whose cross section along the XY plane has a perfect circular shape. A plurality of main bodies 52 are provided corresponding to a plurality of cylindrical bodies 12a. The plurality of main bodies 52 are arranged in parallel with a predetermined gap in the Y direction.

Four protruding pieces 53 are provided on each main body 52 so as to protrude along the Z direction. The protruding pieces 53 here are provided at four equally spaced positions (four equally spaced positions) around the axial direction of each main body 52 when viewed from above. The protruding pieces 53 are plate-shaped extending along the radial direction of the main body 52 and along the Z direction. The protruding pieces 53 are arranged inside the cylindrical body 12a. The upper part of the protruding piece 53 forms a pointed part that points upward. The tip of the upper part of the protruding piece 53 is rounded and chamfered. The connecting part 54 connects the multiple main body parts 52 in a state where they are arranged in parallel with a predetermined gap along the Y direction. The connecting part 54 extends along the Y direction. The connecting part 54 is provided so as to be integral (inseparably integrated) with the main body 52.

The lower linking seat 51 is formed of, for example, a material having acid resistance. Examples of the material of 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, it is preferable that the lower linking seat 51 contains these materials when the cylindrical body 12a contains polyolefin. The lower linking seat 51 may be formed of the same material as the cylindrical body 12a, or may be formed of a material different from the cylindrical body 12a. The material of the lower linking seat 51 is not particularly limited.

9 is a front view showing the core 14, the connecting portion 12e, and the ear 12d. As shown in FIG. 9, the connecting portion 12e connects the upper ends (other ends) of the multiple cores 14 arranged in the Y direction. The connecting portion 12e extends in the Y direction. The connecting portion 12e is provided so as to be continuous with the upper ends of the multiple cores 14. The connecting portion 12e is inserted and fitted into the base 2 of the upper link 1 (see FIG. 5). The connecting portion 12e abuts against the bottom surface 2b of the base 2. One end of the ear 12d is connected to the connecting portion 12e. The other end of the ear 12d is connected to the connecting member 130a (see FIG. 1). The core 14, the connecting portion 12e, and the ear 12d are formed integrally.

The manufacturing method of the lead-acid battery 100 described above includes at least an electrode manufacturing process (electrode manufacturing method) for manufacturing electrodes, and an assembly process (assembly method) for assembling each component to obtain the lead-acid battery 100.

In the electrode manufacturing process, the positive electrode 10 is obtained. The electrode manufacturing process includes the steps of forming a cylindrical body 12a, attaching an upper linking seat 1 to the upper end of the cylindrical body 12a, inserting a core metal 14 into the cylindrical body 12a, filling the cylindrical body 12a with a positive electrode material 16, and sealing the lower end of the cylindrical body 12a with a lower linking seat 51. In the step of inserting the core metal 14 into the cylindrical body 12a, with the upper linking seat 1 attached to the upper end of the cylindrical body 12a, the core metal 14 is inserted into the cylindrical body 12a from its lower end through the cylindrical portion 3 of the upper linking seat 1.

In the assembly process, for example, unformed positive electrodes 10 and unformed negative electrodes 20 are stacked via separators 30, and the current collectors of the electrodes of the same polarity are welded with straps to obtain an electrode group 110. The electrode group 110 is inserted and positioned inside a battery case 120 to produce an unformed battery. Dilute sulfuric acid is poured into the unformed battery and direct current is passed through it to form the battery case. The specific gravity of the sulfuric acid after formation is adjusted to an appropriate specific gravity to obtain a lead-acid battery 100. The formation process is not limited to being performed after the assembly method, and may be performed during the electrode manufacturing method (tank formation).

Next, we will explain the key parts of the positive electrode 10 in this embodiment.

Figure 10(a) is a diagram showing the end face 14a on the lower end side of the core bar 14. Figure 10(b) is a partial cross-sectional view taken along line Xb-Xb in Figure 9. Figure 10(c) is a partial cross-sectional view taken along line Xc-Xc in Figure 1. As shown in Figure 10(a), the end face 14a on the lower end side of the core bar 14 has an elongated shape having a longitudinal direction.

The elongated shape of the end face 14a is specifically a shape in which the Y direction, which is the direction in which the multiple core wires 14 are arranged side by side, is the longitudinal direction, and the X direction, which is the direction perpendicular to the juxtaposition direction, is the transverse direction. The elongated shape of the end face 14a is an ellipse having a major diameter D2 larger than the diameter D1 (see Figure 10 (c)) of the cylindrical hole 52h as a circular hole. The elongated shape of the end face 14a is a shape in which a perfect circle is crushed in the X direction. The elongated shape of the end face 14a is a shape in which a perfect circle is distorted in the X direction.

As shown in FIG. 10(b), at least the upper end of the core 14 has a circular cross section. Specifically, the upper end and central portion of the core 14 have a perfect circular cross section. As shown in FIG. 10(c), one side and the other side in the Y direction, which is the longitudinal direction, of one end of the core 14 are embedded in the inner surface of the tubular hole 52h of the main body 52. In other words, both longitudinal sides of one end of the core 14 enter the inner surface of the tubular hole 52h. In further other words, both longitudinal sides of one end of the core 14 are pressed into the inner surface of the tubular hole 52h so as to deform the inner surface of the tubular hole 52h. One end of the core 14 is fitted into the tubular hole 52h by pressing in such a way that both longitudinal sides are embedded into the inner surface of the tubular hole 52h. For example, one end of the core bar 14 fits inside the inner surface of the cylindrical hole 52h without any gap between it and the inner surface of the cylindrical hole 52h in the longitudinal direction, and is fixed there by the pressure (friction).

7, 8 and 10(c), when viewed from the Z direction, the inner surface of the tubular hole 52h has protruding portions 59 on one side and the other side in the X direction (the short direction of the elongated shape of the core bar 14 inserted into the tubular hole 52h) that protrude from the inner surface. The pair of protruding portions 59 correspond to each other in the X direction. When viewed from the Z direction, the pair of protruding portions 59 protrude (push out) in the X direction from the inner surface of the tubular hole 52h so as to approach each other. The protruding portions 59 have a flat surface 59a that is continuous with the inner surface of the tubular hole 52h and follows the YZ plane.

The manufacturing method of the core bar 14 described above includes a cutting process in which the end of the rod-shaped member constituting the core bar 14 is cut by a cutting device, and a molding process in which the end face on the lower end side of the cut rod-shaped member is shaped to have an elongated shape. In the molding process, when the rod-shaped member is cut by the cutting process, the force required for the cutting is used to shape the end face on the lower end side of the rod-shaped member. The molding process may be performed after the cutting process. In other words, instead of or in addition to forming the elongated shape of the end face when cutting (simultaneously with cutting), the elongated shape of the end face may be formed separately from cutting. As the cutting method and cutting device of the cutting process, various known methods and known devices may be adopted. As the molding method and molding device of the molding process, various known methods and known devices may be adopted.

As described above, in the positive electrode 10, the end face 14a on the lower end side of the core 14 has an elongated shape. The lower end of the core 14 is embedded into the inner surface of the tubular hole 52h of the main body 52 on one and the other longitudinal sides of the elongated shape. Therefore, one end of the core 14 can be firmly fitted into the tubular hole 52h of the main body 52. This makes it possible to improve the fit between the lower connecting seat 51 and the core 14.

The positive electrode 10 includes a cylindrical hole 52h in the main body 52. The elongated shape of the core metal 14 is an ellipse having a major axis larger than the diameter of the cylindrical hole 52h. With this configuration, the lower end of the core metal 14 can be effectively inserted into the inner surface of the cylindrical hole 52h, effectively improving the fit between the lower seat 51 and the core metal 14.

In the positive electrode 10, at least the upper end of the core 14 has a circular cross section. In this case, even if the corrosion of the core 14 progresses and the core 14 becomes thinner, at least the upper end of the core 14 is less likely to form a locally thin portion. This makes it possible to suppress breakage of the core 14. In this case, the active material is more likely to be used evenly around at least the upper end of the core 14 inside the cylindrical body 12a. This makes it possible to improve current collection.

The positive electrode 10 has a cylindrical body 12a. In this case, the active material is more likely to be used evenly inside the cylindrical body 12a. This makes it possible to improve current collection.

When viewed from the Z direction, the positive electrode 10 has a protruding portion 59 that protrudes from the inner surface of the tube hole 52h on one side and the other side in the X direction. If the end face 14a is elongated in the Y direction, a gap will be formed between the end face 14a and the inner surface of the tube hole 52h in the short direction, the X direction. However, the protruding portion 59 can prevent the gap from being formed.

The lead-acid battery 100 includes a positive electrode 10. Since the lead-acid battery 100 also includes a positive electrode 10, the above-mentioned effect of improving the fit between the lower seat 51 and the core metal 14 is achieved.

The core metal 14 is a rod-shaped current collector inserted into the cylindrical body 12a in the positive electrode 10 having the cylindrical body 12a, the positive electrode material 16, and the lower connecting seat 51, and the end face 14a on the lower end side, which is the lower connecting seat 51 side, has an elongated shape. With this core metal 14, for example, when the lower end is fitted into the lower connecting seat 51, one side and the other side of the elongated shape of the lower end can be driven into the lower connecting seat 51 in the longitudinal direction, so that the lower end can be firmly fitted into the lower connecting seat 51. This makes it possible to improve the fit between the lower connecting seat 51 and the core metal 14.

The elongated shape of the end face 14a of the core 14 is an ellipse. In this case, for example, when the lower end of the core 14 is fitted into the lower connecting seat 51, the lower end can be effectively inserted into the lower connecting seat 51, improving the fit between the lower connecting seat 51 and the core 14.

At least the upper end of the core metal 14 has a circular cross section. In this case, even if corrosion of the core metal 14 progresses, at least the upper end of the core metal 14 is less likely to form a locally thin portion. This makes it possible to suppress breakage of the core metal 14. In addition, in this case, the active material is more likely to be used evenly around at least the upper end of the core metal 14 inside the cylindrical body 12a. This makes it possible to improve current collection.

The method for manufacturing the core bar 14 includes a cutting process for cutting the rod-shaped member that constitutes the core bar 14, and a forming process for forming the end face on the lower end side of the cut rod-shaped member into an elongated shape. The core bar 14 manufactured by this manufacturing method allows the lower end of the core bar 14 to be firmly fitted into the lower connecting seat 51, and improves the fit between the lower connecting seat 51 and the core bar 14.

In the manufacturing method of the core bar 14, the forming process forms the end face on the lower end side of the rod-shaped member by utilizing the force required for cutting the rod-shaped member in the cutting process. In this case, the elongated shape of the end face 14a on the lower end side of the core bar 14 can be easily and efficiently realized.

Although the above describes an embodiment, one aspect of the present invention is not limited to the above embodiment.

In one embodiment of the present invention, the end face 14a of the core 14 has an elliptical shape, but is not limited to an elliptical shape and may have any elongated shape having a longitudinal direction. For example, as shown in FIG. 11(a), the end face 14a of the core 14 may have a flattened circular shape. Also, as shown in FIG. 11(b), the end face 14a of the core 14 may have an oval shape (track shape).

As shown in FIG. 11(c), the end face 14a of the core metal 14 may be a rounded rectangular shape. As shown in FIG. 11(d), the end face 14a of the core metal 14 may be a perfect circle on one side in the X direction and an ellipse or flattened circle on the other side in the X direction. As shown in FIG. 11(e), the end face 14a of the core metal 14 may be a shape in which the other side in the X direction is cut off (the edge on the other side in the X direction extends linearly in the Y direction). Incidentally, the end face 14a of the core metal 14 may be a shape that combines at least any of the shapes described above.

In the positive electrode 10 according to one embodiment of the present invention, the upper end and central portion of the core metal 14 have a circular cross section, but only the upper end portion of the core metal 14 may have a circular cross section.
In the positive electrode 10 according to one embodiment of the present invention, when viewed from the Z direction, the protrusions 59 are provided on one and the other sides in the X direction on the inner surface of the cylindrical hole 52h, but the protrusions 59 may be provided only on one or the other side in the X direction, and in some cases, the protrusions 59 may not be provided.

The shape and cross-sectional shape of the end face 14a of the core 14 according to one embodiment of the present invention can be measured by various known methods. The shape and cross-sectional shape of the end face 14a of the core 14 may be measured, for example, by non-destructive testing, X-ray testing, dissolution testing, or testing after removing other portions of the positive electrode 10 by grinding or polishing. The shape and cross-sectional shape of the end face 14a of the core 14 may be measured, for example, before being inserted into the cylindrical hole 52h of the main body 52.

The positive electrode 10 and the lead-acid battery 100 having the lower link seat 51 according to one aspect of the present invention can be used, for example, in an electric vehicle. Examples of electric vehicles include a forklift and a golf cart. In the present invention, the configurations of the above embodiment and the above modified examples may be appropriately combined. The present invention can be modified in various ways without departing from the spirit of the invention.

10...positive electrode (electrode), 12a...cylindrical body, 14...core metal (current collector), 14a...end surface, 16...positive electrode material (electrode material), 51...lower seat (sealing member), 52...main body, 52h...cylindrical hole, 59...protruding portion, 100...lead-acid battery.

Claims (5)

An electrode comprising a cylindrical body, a rod-shaped current collector inserted into the cylindrical body, an electrode material containing an active material filled inside the cylindrical body, and a sealing member sealing one end of the cylindrical body,
the sealing member has a cylindrical main body into which one end of the current collector is fitted,
The end surface of the current collector at the one end side has an elongated shape having a longitudinal direction,
one side and the other side of the elongated shape in the longitudinal direction of the one end of the current collector are embedded into an inner surface of the cylindrical hole of the main body portion,
The current collectors are arranged in parallel,
The other ends of the multiple current collectors are connected by a connecting portion,
An electrode, wherein the elongated shape of the end faces on the one end side of the plurality of current collectors has a longitudinal direction that corresponds to a direction in which the plurality of current collectors are arranged side by side. A lead-acid battery comprising the electrode according to claim 1. In an electrode including a cylindrical body, an electrode material containing an active material filled inside the cylindrical body, and a sealing member sealing one end of the cylindrical body, a rod-shaped current collector is inserted into the cylindrical body,
The end surface of the current collector at one end side has an elongated shape having a longitudinal direction,
The cross section of the other end of the current collector has a circular shape,
The current collectors are arranged in parallel,
The other ends of the multiple current collectors are connected by a connecting portion,
A current collector, wherein the elongated shape of the end faces on the one end side of the plurality of current collectors has a longitudinal direction that corresponds to a direction in which the plurality of current collectors are arranged side by side. A method for producing the current collector according to claim 3, comprising the steps of:
a cutting step of cutting a rod-shaped member constituting the current collector;
and a shaping step of shaping an end face on one end side of the cut rod-shaped member so as to have the elongated shape. A method for manufacturing a rod-shaped current collector to be inserted into a cylindrical body in an electrode including a cylindrical body, an electrode material containing an active material filled inside the cylindrical body, and a sealing member sealing one end of the cylindrical body, comprising the steps of:
The end surface of the current collector at one end side has an elongated shape having a longitudinal direction,
a cutting step of cutting a rod-shaped member constituting the current collector;
and a forming step of forming an end surface of one end of the cut rod-shaped member into the elongated shape,
In the shaping step, an end face on one end side of the rod-shaped member is shaped by utilizing a force required for cutting the rod-shaped member in the cutting step.

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