WO2025205032A1 - Method for producing cylindrical battery, device for producing cylindrical battery, and cylindrical battery - Google Patents

Abstract

This method for producing a cylindrical battery (10) comprises a welding step for welding, to a collector plate (19), an electrode core body exposed part (41) that constitutes a height direction end of an electrode body (14). The method for producing the cylindrical battery (10) comprises a partial load application step for, before the welding step, applying a height direction load to only part of an end face on the height direction end side of the electrode body (14). The partial load application step may be performed a plurality of times in which the region of the end face to which the height direction load is applied is changed. The method for producing a cylindrical battery according to the present disclosure makes it possible to reliably and stably weld, to the collector plate (19), the electrode core body exposed part (41) of the electrode body (14) positioned at said end, and makes it possible to suppress application of an unnecessary load to an electrode (11, 12) at an end on the opposite side from said end of the electrode body (14).

Description

Cylindrical battery manufacturing method, cylindrical battery manufacturing device, and cylindrical battery

This disclosure relates to a method for manufacturing a cylindrical battery, an apparatus for manufacturing a cylindrical battery, and a cylindrical battery.

A conventional cylindrical battery is described in Patent Document 1. In this cylindrical battery, the bottom end of the outer can in the axial direction of the electrode assembly is made up of a negative electrode, and this bottom end is pressed against the negative electrode current collector plate. In this way, a wide longitudinal area of the strip-shaped negative electrode is electrically connected to the negative electrode current collector plate, shortening the current path on the negative electrode side and reducing the electrical resistance of the cylindrical battery.

JP 2014-186912 A

By configuring the first axial end of the electrode body as an exposed negative electrode core portion, welding this exposed negative electrode core portion to the negative electrode current collector plate, and then welding the negative electrode current collector plate to the bottom of the outer can, a wide longitudinal area of the negative electrode can be reliably and stably electrically connected to the negative electrode current collector plate.

Furthermore, when welding the exposed portion of the negative electrode substrate to the negative electrode current collector plate, an axial load is applied to the second axial end of the electrode body to press the exposed portion of the negative electrode substrate against the negative electrode current collector plate, bringing the exposed portion of the negative electrode substrate into contact with the negative electrode current collector plate. Laser light is then irradiated from the outside of the negative electrode current collector plate to weld the negative electrode current collector plate and the exposed portion of the negative electrode substrate.

In light of this background, in order to reliably and stably weld the exposed portion of the negative electrode substrate to the negative electrode current collector plate, it is necessary to ensure that the exposed portion of the negative electrode substrate is in secure contact with the negative electrode current collector plate, and it is necessary to apply the load necessary to ensure good contact to the second end of the electrode body. However, applying such a load to the second end of the electrode body may result in unnecessary load being applied to the electrode plate located at the second end of the electrode body.

The object of the present disclosure is therefore to provide a cylindrical battery manufacturing method and cylindrical battery manufacturing apparatus that can reliably and stably weld the exposed portion of the electrode core located at the first axial end of the electrode body to the current collector plate, and that can suppress unnecessary load on the electrode at the second end of the electrode body. The object of the present disclosure is also to provide a cylindrical battery that is likely to have the exposed portion of the electrode core located at the first axial end of the electrode body reliably and stably welded to the current collector plate, and that is unlikely to have unnecessary load on the electrode at the second end of the electrode body.

In order to solve the above problems, the manufacturing method for a cylindrical battery according to the present disclosure is a manufacturing method for a cylindrical battery that includes a welding step of welding the exposed portion of the electrode core that constitutes the end portion in the height direction of the electrode body to a current collector plate, and includes a partial load application step, prior to the welding step, of applying a height direction load to only a portion of the end face of the electrode body on the end side in the height direction.

In addition, the cylindrical battery manufacturing apparatus according to the present disclosure includes a pressing surface and a pressing mechanism that moves the electrode body relative to the pressing surface to press only a portion of the end surface in the height direction of the electrode body against the pressing surface.

The cylindrical battery manufacturing method and manufacturing apparatus disclosed herein enable the exposed portion of the electrode core located at the first axial end of the electrode body to be reliably and stably welded to the current collector plate, preventing unnecessary load from being applied to the electrode at the second end of the electrode body.

1 is an axial cross-sectional view of a cylindrical battery that can be manufactured by the manufacturing method of the present disclosure. FIG. FIG. 2 is a perspective view showing a portion of the electrode body and the positive electrode lead. FIG. FIG. 2 is a plan view of the negative electrode current collector plate as viewed from below. 10 is a schematic diagram illustrating pre-processing performed on the negative electrode substrate exposed portion that constitutes the lower end portion of the electrode body before welding the electrode body and the negative electrode current collector plate. FIG. FIG. 10 is a diagram illustrating an example of a partial load applying step. 10A and 10B are diagrams for explaining the structure of a welding device used when welding a negative electrode substrate exposed portion to a negative electrode current collector plate, and a welding method. 10A and 10B are diagrams for explaining the structure of a manufacturing device that can be used in a partial load applying step and an example of the partial load applying step. FIG. 1 is a diagram illustrating a problem found by the present inventors. FIG. 2 is a schematic diagram showing the negative electrode of the first reference example developed into a long strip. FIG. 10 is a schematic diagram showing the negative electrode of the second reference example developed into a long strip. FIG. 10 is a schematic diagram showing the negative electrode of the third reference example developed into a long strip. 10A and 10B are diagrams illustrating an example of a second partial load applying step. 10A and 10B are diagrams illustrating an example of a process in which partial load application processing is performed four times. FIG. 10 is a schematic diagram illustrating the structure of a modified battery manufacturing apparatus.

Below, with reference to the drawings, a cylindrical battery manufacturing method and manufacturing apparatus according to the present disclosure, and a cylindrical battery that can be manufactured using the manufacturing method and manufacturing apparatus will be described in detail. Below, a cylindrical lithium-ion battery equipped with a non-aqueous electrolyte will first be described as an example of a cylindrical battery that can be manufactured using the manufacturing method and manufacturing apparatus. Note that cylindrical batteries that can be manufactured using the manufacturing method and manufacturing apparatus are not limited to this. Cylindrical batteries that can be manufactured using the manufacturing method and manufacturing apparatus may be primary batteries or secondary batteries. Furthermore, cylindrical batteries that can be manufactured using the manufacturing method and manufacturing apparatus may be batteries that use either an aqueous electrolyte or a non-aqueous electrolyte.

When the following includes multiple embodiments and variations, it is anticipated from the beginning that new embodiments can be constructed by appropriately combining their characteristic features. In the following embodiments, the same components are designated by the same reference numerals in the drawings, and redundant explanations will be omitted. Furthermore, the multiple drawings include schematic diagrams, and the dimensional ratios of the length, width, height, etc. of each component do not necessarily match between different drawings. In this specification, the side of the sealing body 17 in the axial direction (height direction) is referred to as the upper side, and the side of the bottom 68 of the outer can 16 in the axial direction is referred to as the lower side. Furthermore, in the following description, the radial direction refers to the radial direction of the outer can 16, which coincides with the radial direction of the cylindrical battery 10. Furthermore, the circumferential direction refers to the circumferential direction of the outer can 16, which coincides with the circumferential direction of the cylindrical battery 10. Furthermore, among the components described below, components not recited in the independent claims representing the highest concepts are optional components and are not required components.

FIG. 1 is an axial cross-sectional view of a cylindrical battery 10 according to one embodiment of the present disclosure. As shown in FIG. 1, the cylindrical battery (hereinafter simply referred to as battery) 10 comprises a wound electrode assembly 14, a non-aqueous electrolyte (not shown), a bottomed cylindrical outer can 16 that houses the electrode assembly 14 and the non-aqueous electrolyte, and a sealing body 17 that seals the outer can 16 via a gasket 28.

The electrode assembly 14 includes a long positive electrode 11, a long negative electrode 12, and a separator 13 interposed between the positive electrode 11 and the negative electrode 12, and has a wound structure in which the positive electrode 11 and the negative electrode 12 are wound with the separator 13 interposed therebetween.

The non-aqueous electrolyte has ion conductivity (e.g., lithium ion conductivity). The non-aqueous electrolyte may be a liquid electrolyte (electrolytic solution) or a solid electrolyte. The liquid electrolyte (electrolytic solution) includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of non-aqueous solvents include esters, ethers, nitriles, amides, and mixed solvents of two or more of these. Examples of non-aqueous solvents include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixed solvents of these. The non-aqueous solvent may contain a halogen-substituted solvent (e.g., fluoroethylene carbonate) in which at least a portion of the hydrogen atoms of these solvents are substituted with halogen atoms such as fluorine. The electrolyte salt may be, for example, a lithium salt such as _LiPF6 .

As the solid electrolyte, for example, a solid or gel-like polymer electrolyte, an inorganic solid electrolyte, etc. is used. The polymer electrolyte includes, for example, a lithium salt and a matrix polymer, or a non-aqueous solvent, a lithium salt, and a matrix polymer. As the matrix polymer, for example, a polymer material that absorbs the non-aqueous solvent and gels is used. As the polymer material, for example, fluororesin, acrylic resin, polyether resin, etc. is used. As the inorganic solid electrolyte, for example, a material known in all-solid-state lithium-ion secondary batteries (for example, oxide-based solid electrolytes, sulfide-based solid electrolytes, halide-based solid electrolytes, etc.) is used.

Figure 2 is a perspective view showing a portion of the electrode body 14 and positive electrode lead 20. As shown in Figure 2, the electrode body 14 has a long positive electrode 11, a long negative electrode 12, and two long separators 13, and has a wound structure in which the positive electrode 11 and negative electrode 12 are wound with the separator 13 interposed therebetween. One or more positive electrode leads 20 are joined to the positive electrode 11, and preferably six or more positive electrode leads 20 are joined; in this embodiment, eight positive electrode leads 20 are joined to the positive electrode 11 at intervals from one another in the longitudinal direction of the positive electrode.

The negative electrode 12 is formed with dimensions slightly larger than the positive electrode 11 to prevent lithium precipitation. The negative electrode 12 is formed to be longer than the positive electrode 11 in the winding direction and axial direction. The two separators 13 are formed with dimensions slightly larger than the positive electrode 11 and are arranged to sandwich the positive electrode 11. The separator 13 protrudes upward beyond the positive electrode 11 and negative electrode 12, and the negative electrode 12 protrudes downward beyond the positive electrode 11 and separator 13.

The negative electrode 12 has a negative electrode core exposed portion 41, where the negative electrode mixture layer 42 is not provided on the negative electrode core 40, at the lower axial end from the inner end to the outer end in the negative electrode longitudinal direction of the negative electrode 12. The negative electrode core exposed portion 41 is an example of an electrode core exposed portion. The lower axial end (height direction) of the electrode body 14 is formed by the negative electrode core exposed portion 41. The negative electrode 12 may form the inner end of the electrode body 14. However, typically, the separator 13 extends beyond the inner end of the negative electrode 12, and the inner end of the separator 13 becomes the inner end of the electrode body 14.

The positive electrode 11 has a positive electrode core and positive electrode mixture layers formed on both sides of the positive electrode core. The positive electrode core can be made of a metal foil, such as aluminum or an aluminum alloy, that is stable within the potential range of the positive electrode 11, or a film with such a metal disposed on the surface. The positive electrode mixture layer contains a positive electrode active material, a conductive agent, and a binder. The positive electrode 11 can be produced, for example, by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, and a binder onto the positive electrode core, drying the coating, and then compressing it to form positive electrode mixture layers on both sides of the positive electrode core.

The positive electrode active material is composed primarily of a lithium-containing metal composite oxide. Metal elements contained in the lithium-containing metal composite oxide include Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, Sn, Ta, and W. An example of a preferred lithium-containing metal composite oxide is a composite oxide containing at least one of Ni, Co, Mn, and Al.

Examples of conductive agents contained in the positive electrode mixture layer include carbon black such as acetylene black and ketjen black, and carbon materials such as graphite. Examples of binders contained in the positive electrode mixture layer include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide resin, acrylic resin, and polyolefin resin. These resins may be used in combination with cellulose derivatives such as carboxymethyl cellulose (CMC) or its salts, and polyethylene oxide (PEO).

The positive electrode 11 has one or more positive electrode core exposed portions where the positive electrode core is exposed, and in this embodiment, it has eight positive electrode core exposed portions arranged at intervals in the longitudinal direction of the positive electrode. Positive electrode leads 20 are joined one by one to the positive electrode core exposed portions by ultrasonic welding or the like. Effectively shortening the positive electrode side current path greatly reduces the electrical resistance, so it is preferable that the center positions of the eight positive electrode leads 20 in the longitudinal direction of the positive electrode be arranged at approximately equal intervals in the longitudinal direction of the positive electrode.

As shown in FIG. 2, the negative electrode 12 has a negative electrode core 40 and a negative electrode mixture layer 42 formed on both sides of the negative electrode core 40. The negative electrode core 40 can be made of a metal foil, such as copper or a copper alloy, that is stable within the potential range of the negative electrode 12, or a film with such a metal disposed on the surface. The negative electrode mixture layer 42 contains a negative electrode active material and a binder. The negative electrode 12 can be produced, for example, by applying a negative electrode mixture slurry containing a negative electrode active material and a binder to the negative electrode core 40, drying the coating, and then compressing it to form the negative electrode mixture layer 42 on both sides of the negative electrode core 40.

Anode active materials generally use carbon materials that reversibly absorb and release lithium ions. Preferred carbon materials are graphites such as natural graphites such as flake graphite, lump graphite, and amorphous graphite, and artificial graphites such as lump artificial graphite and graphitized mesophase carbon microbeads. To facilitate increased capacity, the anode active material of the anode mixture layer 42 preferably contains a Si material containing silicon (Si) particles, and the mass ratio of Si element in the anode mixture layer 42 is preferably 5.0 mass% or more. It is also preferable that 3.0 mass% or more of the anode mixture layer be composed of silicon oxide. Metals other than Si that alloy with lithium, alloys containing such metals, compounds containing such metals, etc. may also be used as anode active materials.

As with the positive electrode 11, the binder contained in the negative electrode mixture layer 42 may be fluororesin, PAN, polyimide resin, acrylic resin, polyolefin resin, etc., but styrene-butadiene rubber (SBR) or a modified version thereof is preferred. In addition to SBR, the negative electrode mixture layer 42 may also contain, for example, CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol, etc.

Separator 13 is made of a porous sheet that is ion permeable and insulating. Specific examples of porous sheets include microporous thin films, woven fabrics, and nonwoven fabrics. Preferred materials for separator 13 include polyolefin resins such as polyethylene and polypropylene, and cellulose. Separator 13 may have either a single-layer structure or a laminated structure. A heat-resistant layer or the like may be formed on the surface of separator 13.

As shown in FIG. 1, the battery 10 has a circular insulating plate 18 on the upper side of the electrode body 14. The positive electrode lead 20 attached to the positive electrode 11 passes through a through-hole in the insulating plate 18 and extends toward the sealing body 17. The sealing body 17 has a positive electrode current collector 26 and a terminal cap 27. The positive electrode current collector 26 is a circular metal plate member with a through-hole 26a in its radial center.

The terminal cap 27 is a metal plate-shaped member with no through holes and is located axially above the sealing body 17. The axially upper end face of the terminal cap 27 is exposed to the outside except for the outer edge, and this exposed portion forms the positive electrode terminal. The sealing body 17 further has a metal plate 25. The metal plate 25 is a metal annular member with a through hole.

Each positive electrode lead 20 passes from the positive electrode 11 through the through hole 26a of the positive electrode collector plate 26 and is bent along the upper surface of the positive electrode collector plate 26. The tip of each positive electrode lead 20 is sandwiched between the upper surface of the positive electrode collector plate 26 and the lower surface of the metal plate 25. Each positive electrode lead 20 is bonded to the upper surface of the positive electrode collector plate 26. The positive electrode collector plate 26 and the metal plate 25 are also bonded, and each positive electrode lead 20 and the metal plate 25 are also bonded. These bonds can be achieved, for example, by laser welding the tip of each positive electrode lead 20 sandwiched between the positive electrode collector plate 26 and the metal plate 25 by irradiating the metal plate 25 with a laser beam in the axial direction from above. By laser welding the tip of the positive electrode lead 20 sandwiched between the positive electrode collector plate 26 and the metal plate 25, the positive electrode lead 20 can be reliably and easily welded and bonded to the positive electrode collector plate 26.

The sealing body 17 has a laminated portion 30 on its outer periphery, in which a terminal cap 27 and a positive current collector plate 26 are laminated. By irradiating the laminated portion 30 with a laser beam from above, the terminal cap 27 and the positive current collector plate 26 are laser-welded and electrically connected. The annular upper surface of the positive current collector plate 26 has an annular recess 31 radially inward from the laminated portion 30. Because the upper surface of the positive current collector plate 26 has the recess 31 recessed downward, a space is provided between the terminal cap 27 and the recess 31 of the positive current collector plate 26. Each positive electrode lead 20 is joined to the positive current collector plate 26 within the recess 31. The positive electrode collector plate 26 does not have to be joined to the metal plate 25, and the positive electrode lead 20 does not have to be joined to the metal plate 25. The battery does not have to have a metal plate 25. The positive electrode lead 20 may also be joined to the underside of the positive current collector plate 26.

The battery 10 has a metallic negative electrode current collector 19 axially below the electrode body 14. Figure 3 is a perspective view of the negative electrode current collector 19, and Figure 4 is a plan view of the negative electrode current collector 19 as viewed from below. As shown in Figures 3 and 4, the negative electrode current collector 19 has a flat plate portion 51 that is approximately circular in plan view in its radial center. The flat plate portion 51 may have any flat plate shape other than circular, such as a rectangular shape. The negative electrode current collector 19 also has multiple radially extending portions 53 connected to the flat plate portion 51; in this embodiment, there are four radially extending portions 53. The radially extending portions 53 have a columnar shape and extend radially. It is preferable that the multiple radially extending portions 53 be arranged at equal intervals around the circumference.

1, the radially extending portion 53 is connected to the flat portion 51 via a step portion 54, and the bottom surface of the flat portion 51 is located lower than the bottom surface of the radially extending portion 53. By doing so, when joining the flat portion 51 as described below, the bottom surface of the flat portion 51 can be tightly adhered to the inner surface of the bottom 68 of the outer can 16 without any gaps, making it easier to achieve good joining of the flat portion 51. As shown in FIG. 3, the radially extending portion 53 has a protrusion portion 56 on its upper side. The protrusion portion 56 is provided in the widthwise center of the radially extending portion 53 and protrudes in the thickness direction. The protrusion portion 56 extends in the radial direction. A groove portion 57 extending in the radial direction is provided at a location on the underside of the radially extending portion 53 that overlaps the protrusion portion 56 in the thickness direction. The widthwise center portion of the underside of the radially extending portion 53 is pressed upward in the thickness direction by a predetermined radial distance. This press forming process forms the protrusions 56 and grooves 57.

The negative electrode core exposed portion 41 (see Figure 2) is joined to the protrusion portion 56. More specifically, while the negative electrode core exposed portion 41, which constitutes the lower end of the electrode body 14, is pressed against the protrusion portion 56, laser light is irradiated from below toward the bottom of the groove portion 57. This laser light irradiation joins the negative electrode core exposed portion 41 of the electrode body 14 to the protrusion portion 56 by laser welding over a wide radial area.

Then, a presser rod (not shown) inserted from above into the hollow portion 14a of the electrode body 14 (see Figure 1) presses the upper surface of the flat portion 51 against the inner surface of the bottom portion 68 of the outer can 16. With this in place, laser light is irradiated from below the outer can 16 to laser-weld the bottom portion 68 to the negative electrode current collector plate 19. This electrically connects the negative electrode 12 of the electrode body 14 to the outer can 16 via the negative electrode current collector plate 19. By joining the negative electrode core exposed portion 41 over a wide area to the upper surface of the negative electrode current collector plate 19, it is possible to prevent current from flowing long distances along the longitudinal direction of the elongated negative electrode 12, thereby reducing the electrical resistance of the battery 10.

As shown in FIG. 1, the outer can 16 has a cylindrical portion 39 and a bottom portion 68, and the cylindrical portion 39 includes an annular grooved portion 22 and an annular shoulder portion 29. The grooved portion 22 is formed by spinning a portion of the cylindrical portion 39 to recess it radially inward around the entire circumferential direction. The sealing body 17 is placed on the grooved portion 22 and is crimped and fixed to the opening of the outer can 16 via a resin gasket 28. The shoulder portion 29 is formed when the upper end of the cylindrical portion 39 is bent radially inward and crimped to the outer edge of the sealing body 17, and extends radially inward at the upper end of the cylindrical portion 39.

The internal space of the battery 10 is sealed by sealing the space between the outer can 16 and the sealing body 17 with an annular gasket 28. The gasket 28 is sandwiched between the outer can 16 and the sealing body 17, and insulates the sealing body 17 from the outer can 16. The gasket 28 serves as a sealant to maintain airtightness inside the battery, and as an insulating material to insulate the outer can 16 from the sealing body 17. The terminal cap 27 electrically connected to the positive electrode lead 20 serves as the positive electrode terminal, and the outer can 16 electrically connected to the negative electrode core exposed portion 41 via the negative electrode current collector plate 19 serves as the negative electrode terminal.

The battery 10 has a thin, easily breakable portion 68a on the bottom 68 of the outer can 16. The easily breakable portion 68a is formed, for example, by stamping a circle or C-shape on the underside of the bottom 68. By providing the easily breakable portion 68a on the bottom 68, if the battery 10 generates abnormal heat, the easily breakable portion 68a will break, allowing high-temperature gas inside the battery 10 to be released to the outside, thereby increasing the safety of the battery 10. The thin, easily breakable portion may also be provided on the terminal cap.

In the above description, the sealing body 17 does not have a rupture plate, and an easily breakable portion 68a is provided on the bottom 68 of the outer can. However, the bottom of the outer can does not have to have an easily breakable portion. The sealing body may also have two rupture plates (a lower valve body and an upper valve body) and a convex terminal cap that covers the rupture plates. Alternatively, the sealing body may be composed of only a rupture plate, or may have a structure in which an internal terminal plate, an insulating plate, and a rupture plate are stacked in this order from the electrode body side.

Next, a method for joining the electrode body 14 and the negative electrode current collector plate 19 in the battery 10 will be described in detail. Figure 5 is a schematic diagram illustrating the pre-processing performed on the negative electrode core exposed portion 41 that constitutes the lower end of the electrode body 14 before welding the electrode body 14 and the negative electrode current collector plate 19 together (before the welding process). Note that below, when simply referring to welding or during welding, welding refers to the welding of the electrode body 14 and the negative electrode current collector plate 19, and during welding refers to the welding of the electrode body 14 and the negative electrode current collector plate 19.

In this pre-processing, first, a bending process (bending step) is performed to bend the negative electrode substrate exposed portion 41 radially inward. Figure 5(a) is a plan view illustrating the bending process, showing the electrode body 14 as it is being bent, viewed from below in the height direction (below in the axial direction).

Referring to Figure 5(a), the bending of the negative electrode substrate exposed portion 41 radially inward during the bending process is performed as follows. First, the electrode body 14 is fixed at a predetermined position in three-dimensional space by a holding device (not shown). Next, multiple flat bending plates 80, 81 (not shown) are moved from the radially outer side to the radially inner side of the electrode body 14 on a plane approximately perpendicular to the height direction of the electrode body using multiple linear actuators (not shown). At this time, the bending plates 80, 81 are moved at a height position where they come into contact with the negative electrode substrate exposed portion 41. In this way, the negative electrode substrate exposed portion 41 is tilted radially inward, bent radially inward, and flexed radially inward.

In this embodiment, four first bending plates 80 and four second bending plates 81 are used to bend the negative electrode core exposed portion 41 radially inward. The four first bending plates 80 have a long, narrow rectangular planar shape. The four first bending plates 80 are arranged at equal intervals in the circumferential direction, and in Figure 5(a), with the central axis 80a of the first bending plate 80 approximately aligned with the radial direction of the electrode body 14, the first bending plate 80 moves from the radially outer side to the radially inner side of the electrode body 14.

On the other hand, the tip 81a of the second folded plate 81 has the shape of a right-angled isosceles triangle with an apex angle of 90 degrees. In Figure 5(a), when the extension line of the bisector 81b of the right-angled isosceles triangle forms approximately 45 degrees with the central axis 80a of the first folded plate 80, the second folded plate 81 moves from the radially outer side to the radially inner side of the electrode body 14. As the second folded plate 81 moves, a portion of the negative electrode core exposed portion 41 in the circumferential region sandwiched between the movement regions of the circumferentially adjacent first folded plates 80 is bent and tilted radially inward, and is formed radially inward.

The eight folded plates 80, 81 may simultaneously move from the radially outer side to the radially inner side, or the four first folded plates 80 may move from the radially outer side to the radially inner side, and then the four second folded plates 81 may move from the radially outer side to the radially inner side. Or, the four second folded plates 81 may move from the radially outer side to the radially inner side, and then the four first folded plates 80 may move from the radially outer side to the radially inner side.

FIG. 5(b) is a plan view showing the state of the first end surface 85 on the negative electrode core exposed portion 41 side of the electrode body 14 after bending. In FIG. 5(b), the light gray region 46 indicates the region where the negative electrode core exposed portion 41 bent radially inward is present, and the dark gray region 47 indicates the region where the negative electrode core exposed portion 41 is present, protruding downward in the height direction from the light gray region 46. The dark gray region 47 is a region where the negative electrode core exposed portion 41 is denser and harder. As shown in FIG. 5(b), four approximately V-shaped protruding portions of the negative electrode core exposed portion 41 (dark gray regions 47) are present on the first end surface 85 of the electrode body 14 after bending.

Once the bending process is complete, a partial load application process (partial load application step) is performed, in which a load in the height direction is applied only to a portion of the first end face 85. In the example shown in Figure 5(c), when the first end face 85 is divided into four, a load is applied only to the first region 85a located at the upper right and the third region 85c located at the lower left, and no load is applied to the second region 85b located at the lower right and the fourth region 85d located at the upper left. Each of the regions 85a, 85b, 85c, and 85d has the same shape and size, and is fan-shaped in plan view. The inner edge on the inner periphery and the outer edge on the outer periphery of each of the regions 85a, 85b, 85c, and 85d have concentric arc shapes.

Such partial load application can be performed, for example, using the manufacturing apparatus 60 shown in Figure 8. Note that when explaining the manufacturing apparatus 60 in Figure 8, the explanatory diagram of the partial load application process in Figure 6 will be referenced as appropriate. For ease of understanding, Figure 6 omits part of the manufacturing apparatus 60 and shows the positional relationship between the electrode body 14, pressure plate 62, and plate mounting portion 63. The manufacturing apparatus 60 includes the pressure surface 61 shown in Figure 6 and a pressure mechanism (reference numeral 65 in Figure 8) that moves the electrode body 14 relative to the pressure surface 61 to press only a portion of the first end surface 85 against the pressure surface 61. In this embodiment, as shown in Figure 6, the pressure surface 61 is formed by one side of the pressure plate 62 provided at a predetermined position in three-dimensional space, and the pressure plate 62 is fixed to the plate mounting portion 63 provided at a predetermined position in three-dimensional space.

As shown in Figure 6, the plate mounting portion 63 is composed of a plate-shaped portion with a cylindrical hole 63a having a diameter slightly larger than the outer diameter of the electrode body 14. The pressure plate 62 is fixed to the bottom surface of the cylindrical hole 63a with fixing means such as double-sided tape or adhesive. The pressure plate 62 may be detachable from the plate mounting portion 63, or may be configured integrally with the plate mounting portion 63.

As shown in FIG. 8, the pressing mechanism 65 includes a base stage 65a, a movable stage 65b that is movable relative to the base stage 65a in a first direction indicated by arrow A in FIG. 8, and a holding device 65c installed on the movable stage 65b. The movable stage 65b is slidable in the first direction relative to the base stage 65a. In this embodiment, the electrode body 14 is held by the holding device 65c and fixed to the movable stage 65b.

The first direction roughly coincides with the thickness direction of the plate mounting portion 63 (thickness direction of the pressing plate 62). With the extension of the central axis of the electrode body 14 held by the holding device 65c roughly coincident with the central axis of the cylindrical hole 63a in Figure 6, the moving stage 65b slides (moves relative to) the base stage 65a in the first direction. The pressing mechanism 65 is equipped with a pressing device (not shown) including a linear actuator. The pressing device has an extendable rod, and the tip surface of the rod presses with a predetermined force in the first direction against a second end face of the electrode body 14 held by the holding device 65c on the side opposite the negative electrode core exposed portion 41 in the axial direction.

As shown in FIG. 6, the pressure plates 62 have a planar shape corresponding to the above-mentioned regions 85a, 85b, 85c, and 85d. With the two pressure plates 62 fixed in the cylindrical hole 63a at locations corresponding to the first region 85a and third region 85c, the moving stage 65b in FIG. 8 is moved relative to the base stage 65a in the first direction as shown in (a) to (c) of FIG. 8, pressing the first end surface 85 of the electrode body 14 against the two pressure plates 62 fixed in the cylindrical hole 63a. In this way, a load can be applied only to the first region 85a and third region 85c of the first end surface 85 of the electrode body 14.

The exposed portions of the negative electrode substrate located in the first region 85a and the third region 85c are crushed toward the center of the height direction of the electrode body 14 during the partial load application process. Therefore, as shown in Figure 5(d), after the partial load application process, the exposed portions of the negative electrode substrate located in the first region 85a and the third region 85c are located closer to the center of the height direction of the electrode body 14 than the region (raised portion) 47 shown in dark gray.

Once the partial load application process is complete, the negative electrode substrate exposed portion 41 is welded to the negative electrode current collector plate 19. Figure 7 is a diagram illustrating the structure of a welding device 90 used to perform this welding, and the welding method. As shown in Figure 7, the welding device 90 includes a metal plate 91 and a pressing mechanism 92. The metal plate 91 is installed at a predetermined location in three-dimensional space and remains stationary at that location. The pressing mechanism 92 also includes a base stage 92a, a movable stage 92b that is movable relative to the base stage 92a in the direction indicated by arrow B in Figure 7, a holding device 92c installed on the movable stage 92b, and a pressing device (not shown).

The metal plate 91 is, for example, rectangular and has one or more slits in the thickness direction. The negative electrode current collector 19 (see Figure 3) is fixed to one side of the metal plate 91 with a magnet so that the four grooves 57 overlap the slits in the thickness direction of the metal plate 91.

With the negative electrode current collector 19 fixed to the metal plate 91, the second end face 86 on the axial side of the electrode body 14 opposite the exposed negative electrode core portion (the non-welded side in the axial direction) is pressed, and the first end face 85 is pressed with a predetermined force against the end face of the negative electrode current collector 19 on the side where the protrusion portion 56 is formed.

The load applied to the second end surface 86 of the electrode body 14 is received by the metal plate 91 and transferred to the first end surface 85 of the electrode body 14 according to the law of action and reaction. During this pressure, the bent portions of the negative electrode substrate exposed portion 41 that have been bent radially inward by the four first bent plates 80 (see Figure 5(a)) are pressed against the protrusion portions 56.

With the formed portion pressed against the protrusion 56, a laser beam is emitted toward the slit from the side of the metal plate 91 opposite the fixed side of the negative current collector plate 19, irradiating the groove 57 of the negative current collector plate 19. This laser beam welds the formed portion to the protrusion 56, thereby joining the electrode body 14 to the negative current collector plate 19 and integrating them. During laser welding, spatter occurs at the point irradiated with the laser beam. The metal plate 91 prevents this spatter from scattering toward the electrode body 14.

Next, the problem discovered by the inventors and the effects of the technology disclosed herein will be explained using Figure 9. By configuring the first axial end of the electrode body as a negative electrode substrate exposed portion, welding this negative electrode substrate exposed portion to the negative electrode current collector plate, and then welding the negative electrode current collector plate to the bottom of the outer can, a wide longitudinal area of the negative electrode can be reliably and stably electrically connected to the negative electrode current collector plate.

Furthermore, when welding the exposed portion of the negative electrode substrate to the negative electrode current collector plate, an axial load is applied to the second axial end of the electrode body to press the exposed portion of the negative electrode substrate against the negative electrode current collector plate, bringing the exposed portion of the negative electrode substrate into contact with the negative electrode current collector plate. Laser light is then irradiated from the outside of the negative electrode current collector plate to weld the negative electrode current collector plate and the exposed portion of the negative electrode substrate.

In this context, in order to reliably and stably weld the exposed portion of the negative electrode substrate to the negative electrode current collector plate, it is necessary to ensure that the exposed portion of the negative electrode substrate is in secure contact with the negative electrode current collector plate, and it is necessary to apply the load required to ensure good contact to the second end of the electrode body.

On the other hand, if the load necessary to ensure contact is applied to the second end of the electrode body, there is a risk that unnecessary load will be applied to the electrode. This issue is not limited to the following example, but it also becomes a significant problem in the following cases, for example. That is, when the electrode body is wound onto the winding core, the electrodes (positive and negative electrodes) may meander, and as shown in Figure 9, this meandering may cause electrodes 211 and 212 to locally protrude outward in the axial direction. For example, Figure 9 shows a state in which a part of electrode 212, i.e., electrode portion 212a, locally protrudes outward in the axial direction. In such a case, if the load necessary to ensure the above-mentioned contact is applied to the second end of electrode body 214, there is a risk that unnecessary load will be applied to electrode portion 212a protruding outward in the axial direction.

In contrast, according to the technology disclosed herein, a load is applied in advance to a portion of the negative electrode substrate exposed portion 41 that constitutes the lower end of the electrode body 14 by the partial load application process described above, before welding, and the portion of the negative electrode substrate exposed portion 41 is crushed toward the center in the height direction of the electrode body 14 in advance before welding. Furthermore, because the portion of the negative electrode substrate exposed portion that is crushed by the partial load application process is only a portion of the negative electrode substrate exposed portion 41, the load applied to the electrode body 14 by the partial load application process is smaller than the load that would be required to crush the entire negative electrode substrate exposed portion 41.

Furthermore, when welding the negative electrode substrate exposed portion 41 to the negative electrode current collector plate 19, the load applied to the electrode body 14 need only be the load necessary to crush the portion of the negative electrode substrate exposed portion 41 to which no load was applied during the partial load application process toward the center of the height of the electrode body 14, and this load can be used to preferentially crush this portion toward the center of the height of the electrode body 14.

Therefore, the load applied to the electrode assembly 14 when welding the negative electrode substrate exposed portion 41 to the negative electrode current collector plate 19 is also smaller than the load required to crush the entire negative electrode substrate exposed portion 41. Therefore, the technology disclosed herein can simultaneously achieve the exceptional and significant effect of reliably and stably welding the negative electrode substrate exposed portion 41 to the negative electrode current collector plate 19, which are in a trade-off relationship, and suppressing the application of unnecessary load to the electrode ends (positive electrode 11 end, negative electrode 12 end) on the axial side of the electrode assembly 14 opposite the negative electrode substrate exposed portion 41.

In this embodiment, a load is applied before welding to only approximately half of the negative electrode substrate exposed portion 41 that constitutes the first end surface 85 of the electrode body 14. Therefore, if the load required to crush the entire negative electrode substrate exposed portion 41 is defined as load N, the load required in the partial load application process and the load required in the welding process can both be approximately load N/2. In other words, according to this embodiment, the load applied to the electrode end portion on the opposite side of the electrode body 14 from the negative electrode substrate exposed portion 41 can be rapidly reduced to approximately half the load.

As shown in FIG. 6, the partial load application process is preferably performed by pressing only a portion of the first end surface 85 with the pressing surface 61, and a protrusion 62a is preferably provided on the pressing surface 61 at a location corresponding to the welding location of the negative electrode substrate exposed portion 41 to be welded in the welding process. In this embodiment, the protrusion 62a is formed as a ridge portion, and extends on a bisector that bisects the fan-shaped pressing surface 61 of the pressing plate 62. The protrusion 62a is provided to press the negative electrode substrate exposed portion that is joined to the ridge portion 56 of the negative electrode current collector plate 19 (see FIG. 3).

As described above, when the negative electrode substrate exposed portion 41 is bent radially inward using the flat folding plates 80, 81, a hard raised portion (area 47 shown in dark gray) is created. This raised portion is not easily crushed even when a load is applied, so if this raised portion falls toward the welded portion, it becomes difficult to perform a good weld. By providing a convex portion (protruding portion) 62a on the pressing surface 61, it is possible to effectively prevent the raised portion from falling toward the welded portion.

It is preferable that the pressing surface 61 does not overlap the electrode located at the innermost periphery on the first end face 85 in the height direction of the electrode body, and in the partial load application process, it is preferable that a load in the height direction is applied only to a portion of the area located radially outward from the electrode located at the innermost periphery on the first end face 85. When winding the electrode body 14 around the winding core, the electrode plate at the start of winding tends to meander. By doing so, it is possible to effectively prevent unnecessary load from being applied to the electrode plate at the start of winding.

FIG. 10 is a schematic diagram of the negative electrode 312 of the first reference example unfolded into a long strip, and FIG. 11 is a schematic diagram of the negative electrode 412 of the second reference example unfolded into a long strip. Furthermore, FIG. 12 is a schematic diagram of the negative electrode 512 of the second reference example unfolded into a long strip. The shaded areas in FIGS. 10 and 11 are the areas where the negative electrode mixture layers 342, 442, and 542 are arranged.

As shown in FIG. 10, in the negative electrode 312 of the first reference example, the negative electrode substrate exposed portions 341 are provided at intervals in the longitudinal direction of the negative electrode. Furthermore, as shown in FIG. 11, in the negative electrode 412 of the second reference example, the negative electrode substrate exposed portions 441 are not present at either end in the longitudinal direction of the negative electrode. Furthermore, as shown in FIG. 12, in the negative electrode 512 of the third reference example, a notch 541a is made in the negative electrode substrate exposed portion 541. In these cases, the rigidity of the negative electrode substrate exposed portions 341, 441, 541 is reduced, making the negative electrode substrate exposed portions 341, 441, 541 more likely to be crushed in the axial direction of the electrode body, and reducing the load applied to the electrode body when welding the negative electrode substrate exposed portions 341, 441, 541 to the negative electrode current collector plate 19.

In contrast, as shown in Figure 2, in this embodiment, the negative electrode substrate exposed portion 41 has a band shape that extends from the inner end of the winding to the outer end of the winding in the longitudinal direction of the negative electrode 12, and the negative electrode substrate exposed portion 41 does not have any notches. Therefore, the rigidity of the negative electrode substrate exposed portion 41 is high, the negative electrode substrate exposed portion 41 is less likely to be crushed in the axial direction, and the load required to press the negative electrode substrate exposed portion 41 in the axial direction is large. Therefore, the effects achieved by the technology disclosed herein are remarkable.

In this embodiment, the partial load application process was performed once by pressing the first end surface 85 of the electrode body 14 against the two pressure plates 62 while the two pressure plates 62 were fixed at locations corresponding to the first region 85a and third region 85c within the cylindrical hole 63a. However, the partial load application process may be performed multiple times by changing the end surface region to which the load is applied in the height direction of the electrode body.

For example, after performing the partial load application process (see FIG. 6 ) with two pressure plates 62 fixed in positions corresponding to the first region 85a and the third region 85c within the cylindrical hole 63a, a second partial load application process may be performed with two additional pressure plates 62 fixed in positions corresponding to the second region 85b and the fourth region 85d within the cylindrical hole 63a, as shown in FIG. 13 . In this way, the negative electrode substrate exposed portion 41 can be crushed toward the center in the height direction of the electrode body 14 along the entire circumferential direction before welding the negative electrode substrate exposed portion 41 to the negative electrode current collector plate 19. This further reduces the load applied to the electrode body 14 when welding the negative electrode substrate exposed portion 41 to the negative electrode current collector plate 19, significantly reducing the possibility of unnecessary load being applied to the electrode end of the electrode body 14 on the side opposite the negative electrode substrate exposed portion 41.

Alternatively, partial load applying processing may be performed three or more times. For example, as shown in FIG. 14, partial load applying processing may be performed four times with one more pressing plate 62 than in the previous partial load applying processing. In this case, four different plate mounting portions 63 may be spaced apart in a second direction indicated by arrow C, which is perpendicular to the first direction, to provide four stations for performing partial load applying processing. Then, once partial load applying processing other than the fourth is completed, the base stage 65a may be moved in the second direction using a ball screw, linear slider, conveyor, or the like to the processing position (station) for the next partial load applying processing, and the next partial load applying processing may be performed.

In this way, the load applied to the electrode body 14 in each partial load application process can be further rapidly reduced to approximately one-quarter of the load required to crush the entire negative electrode substrate exposed portion 41, and it is possible to almost reliably prevent unnecessary load from being applied to the electrode end portion of the electrode body 14 on the side opposite the negative electrode substrate exposed portion 41. In addition, in the mechanism that performs four partial load application processes shown in Figure 14, only one pressing plate 62 may be attached to four different plate attachment portions 63 at mutually different positions.

The present disclosure is not limited to the above-described embodiment and its variations, and various improvements and modifications are possible within the scope of the claims of the present application and their equivalents. For example, in the above-described embodiment, the electrode body 14 is moved toward the stationary pressing surface 61, and the first end surface 85 of the electrode body 14 is pressed by the pressing surface 61. However, the pressing surface may be moved toward the stationary first end surface of the electrode body and the first end surface may be pressed by the pressing surface, or both the electrode body and the pressing surface may move during partial load application processing, and the first end surface may be pressed by the pressing surface.

Figure 15 is a schematic diagram illustrating the structure of a modified battery manufacturing apparatus 160. More specifically, Figure 15(a) is a side view showing the rod 162 of the manufacturing apparatus 160 and the electrode body 14 before it comes into contact with the rod 162, and Figure 15(b) is a plan view of the rod 162 and electrode body 14 in the state shown in Figure 15(a) when viewed from the axial outside of the first end surface 85 of the electrode body 14.

As shown in Figure 15(b), the manufacturing apparatus 160 has four identical rods 162 arranged in two rows and two columns in a matrix. Each rod 162 is a rod of a linear actuator and is extendable in one direction relative to the linear actuator case (not shown). The tip surface 161 of the rod 162 has the same structure as the pressing surface 61 of the above-mentioned pressing plate 62, and has a convex portion 162a having the same structure as the convex portion 62a. The second axial end surface of the electrode body 14 is in contact with a stationary plane. The linear actuator case is fixed immovably at a predetermined position in three-dimensional space. The electrode body 14 is held movably in its height direction by a holding device (not shown). In this state, by extending the rod 162 of the linear actuator, the tip surface 161 of the rod 162 presses a partial area of the first end surface 85 of the electrode body 14. In this way, as the tip surface 161 presses against the first end surface 85 of the electrode body 14, the second end surface of the electrode body 14 is pressed against the stationary plane.

In such a case, for example, if two rods 162 are extended simultaneously and first, and then the remaining two rods 162 are extended simultaneously, a process equivalent to the two-stage partial load application process described above can be achieved. Furthermore, if four rods 162 are extended at different times with a time lag, a process equivalent to the four-stage partial load application process described using FIG. 14 can be achieved. Compared to manufacturing apparatus 60, the manufacturing apparatus 160 of the modified example can be constructed more compactly and can easily perform processing in a shorter time. Therefore, if the manufacturing apparatus 160 is used to perform partial load application processing, it is easy to shorten the cycle time and improve the mass productivity of the battery 10.

The manufacturing device may have only one rod 162. The case of the linear actuator may then be fixed to a rotary stage, and the rotary stage may be rotated to move the processing position of the rod 162 in the circumferential direction of the electrode body.

Furthermore, the partial region of the first end face 85 of the electrode body 14 to which a load is applied by the partial load application process has been described as being a partial region in the circumferential direction of the first end face 85. However, the region to which a load is applied by the partial load application process may be any partial region on the end face on the electrode core exposed portion side of the electrode body. For example, the partial region to which a load is applied by the partial load application process may be an outer peripheral region located radially outward over the entire circumferential direction on the end face on the electrode core exposed portion side of the electrode body, or an inner peripheral region located radially inward over the entire circumferential direction on the end face on the electrode core exposed portion side of the electrode body.

Furthermore, in the above description, the electrode core exposed portion is the negative electrode core exposed portion 41 that constitutes the end portion in the height direction of the electrode body 14, and the technology disclosed herein is used to prevent unnecessary loads from being applied to the electrodes (positive electrode 11 and negative electrode 12) when welding the negative electrode core exposed portion 41 to the negative electrode current collector plate 19. However, the electrode core exposed portion may also be a positive electrode core exposed portion that constitutes the end portion in the height direction of the electrode body, and the technology disclosed herein may also be used to prevent unnecessary loads from being applied to the electrodes (positive electrode and negative electrode) when welding the positive electrode core exposed portion to the positive electrode current collector plate.

The cylindrical battery manufacturing method, cylindrical battery manufacturing apparatus, and cylindrical battery of the present disclosure may also have the following configurations.
Configuration 1: A method for manufacturing a cylindrical battery, which includes a welding step of welding an exposed portion of an electrode core that constitutes an end portion in the height direction of an electrode body to a current collector plate, and which includes a partial load application step of applying a height direction load to only a portion of the end face on the end side in the height direction of the electrode body before the welding step.
Configuration 2: The method for manufacturing a cylindrical battery according to Configuration 1, wherein in the partial load application step, a height direction load is applied only to a portion of a region located radially outward from an electrode located radially innermost on the end face.
Configuration 3: The method for manufacturing a cylindrical battery according to Configuration 1 or 2, wherein the partial load application step is performed multiple times by changing the region of the end face to which the height direction load is applied.
Configuration 4: The method for manufacturing a cylindrical battery according to any one of Configurations 1 to 3, wherein the partial load application step is performed by pressing only a portion of the end face against a pressing surface, and a convex portion is provided on the pressing surface at a corresponding location that corresponds to a welding location of the electrode core exposed portion that is to be welded in the welding step.
Configuration 5: The method for manufacturing a cylindrical battery according to any one of Configurations 1 to 4, wherein the portion of the end face is included in a partial region of the end face in the circumferential direction.
Configuration 6: The method for manufacturing a cylindrical battery according to any one of Configurations 1 to 5, wherein the electrode substrate exposed portion has a band shape that extends from the inner end of the electrode to the outer end of the electrode in the longitudinal direction of the electrode, and the electrode substrate exposed portion does not have a notch.
Configuration 7: A cylindrical battery manufacturing device comprising: a pressing surface; and a pressing mechanism that moves the electrode body relative to the pressing surface to press only a portion of the height-wise end surface of the electrode body against the pressing surface.
Configuration 8: The cylindrical battery manufacturing apparatus according to Configuration 7, wherein, when a portion of the end face is pressed against the pressing surface, the pressing surface is positioned radially spaced apart from the radially inner side of the end face.
Configuration 9: A cylindrical battery manufacturing apparatus according to configuration 7 or 8, wherein the pressing mechanism comprises a linear actuator having one or more extendable rods, and the tip surface of at least one of the rods constitutes the pressing surface.
Configuration 10: The cylindrical battery manufacturing apparatus according to any one of Configurations 7 to 9, wherein the portion of the end face is included in a partial region of the end face in the circumferential direction.
Configuration 11: A cylindrical battery manufactured by the method for manufacturing a cylindrical battery according to any one of configurations 1 to 6.

REFERENCE SIGNS LIST 10 battery, 11 positive electrode, 12 negative electrode, 13 separator, 14 electrode body, 14a hollow portion, 16 outer can, 17 sealing body, 18 insulating plate, 19 negative electrode current collector plate, 20 positive electrode lead, 22 grooved portion, 25 metal plate, 26 positive electrode current collector plate, 26a through hole, 27 terminal cap, 28 gasket, 29 shoulder portion, 30 stacked portion, 31 recessed portion, 39 cylindrical portion, 40 negative electrode core, 41 negative electrode core exposed portion
42 Negative electrode mixture layer, 51 Flat plate portion, 53 Radial extending portion, 54 Step portion, 56 Protrusion portion, 57 Groove portion, 60 Manufacturing device, 61 Pressing surface, 62 Pressing plate, 62a Convex portion, 63 Plate mounting portion, 63a Cylindrical hole, 65 Pressing mechanism, 65a Base stage, 65b Moving stage, 65c Holding device, 68 Bottom portion, 68a Easy-to-break portion, 80 First folded plate, 80a Central axis, 81 Second folded plate, 81a Tip portion of second folded plate, 81b Bisector, 85 First end surface of electrode body, 85a First region of first end surface in plan view, 85b Second region of first end surface in plan view, 85c a third region of the first end surface in plan view; 85d a fourth region of the first end surface in plan view; 86 a second end surface of the electrode body; 90 welding device; 91 metal plate; 92 pressing mechanism; 92a base stage; 92b moving stage; 92c holding device; 160 manufacturing device; 161 tip surface; 162 rod; 162a convex portion.

Claims (11)

A method for manufacturing a cylindrical battery, comprising a welding step of welding an electrode core exposed portion that constitutes an end portion in the height direction of an electrode body to a current collector plate,
A method for manufacturing a cylindrical battery, comprising, before the welding step, a partial load applying step of applying a load in the height direction to only a portion of the end face on the end side in the height direction of the electrode body. The method for manufacturing a cylindrical battery described in claim 1, wherein, in the partial load application step, a height direction load is applied only to a portion of an area of the end face that is located radially outward from the electrode located at the innermost periphery in the radial direction. The method for manufacturing a cylindrical battery described in claim 1 or 2, wherein the partial load application process is performed multiple times by changing the area of the end face to which the height direction load is applied. the partial load applying step is performed by pressing only a portion of the end surface against a pressing surface,
The method for manufacturing a cylindrical battery according to claim 1 or 2, wherein a protrusion is provided on the pressing surface at a position corresponding to a welding position of the electrode core exposed portion to be welded in the welding step. The method for manufacturing a cylindrical battery according to claim 1 or 2, wherein a portion of the end face is included in a circumferential region of the end face. The method for manufacturing a cylindrical battery described in claim 1 or 2, wherein the electrode substrate exposed portion has a band shape extending from the inner end of the electrode to the outer end of the electrode in the longitudinal direction of the electrode, and the electrode substrate exposed portion does not have a notch. A pressing surface;
a pressing mechanism that moves the electrode body relative to the pressing surface to press only a portion of the end surface in the height direction of the electrode body against the pressing surface;
A cylindrical battery manufacturing apparatus comprising: The cylindrical battery manufacturing apparatus of claim 7, wherein, when a portion of the end face is pressed against the pressing surface, the pressing surface is positioned radially away from the radially inner side of the end face. the pressing mechanism includes a linear actuator having one or more extendable rods;
The cylindrical battery manufacturing apparatus according to claim 7 or 8, wherein a tip surface of at least one of the rods constitutes the pressing surface. The cylindrical battery manufacturing apparatus of claim 7 or 8, wherein a portion of the end face is included in a circumferential region of the end face. A cylindrical battery manufactured using the cylindrical battery manufacturing method described in claim 1.