Cylindrical secondary battery

Abstract

A cylindrical secondary battery (10) includes: an electrode group (14); a cylindrical metal can (16) having an opening at one end, the electrode group being accommodated in the metal can; a current collecting component connected to the electrode group inside the metal can; a sealing body having an electrode terminal exposed to the outside, the sealing body closing off the opening; and a conductive component (60) connected to the current collecting component and the sealing body inside the metal can. The conductive component has a central-side plate part (61) following a plane orthogonal to the central axis, inclined parts (62) extending from a plurality of positions in the circumferential direction of the outer periphery of the central-side plate part toward the outer peripheral side in an oblique direction, and an outer-peripheral-side plate part connected to the outer-peripheral-side end of each inclined part. In each inclined part, a thin part (68), which extends so as to reach both circumferential-direction ends of the inclined part and has a smaller thickness than portions adjacent to both sides, is formed in a part connected to the central-side plate part.

Description

Cylindrical secondary battery

[0001] The present disclosure relates to a cylindrical secondary battery.

[0002] Cylindrical secondary batteries using cylindrical metal cans have been known. For example, in nonaqueous electrolyte secondary batteries, an electrode group including a positive electrode plate, a negative electrode plate, and a separator between the positive and negative electrode plates, and a nonaqueous electrolyte are housed in a metal can. Cylindrical nonaqueous electrolyte secondary batteries include a wound electrode group in which the positive electrode plate and the negative electrode plate are spirally wound with the separator interposed therebetween.

[0003] Patent Document 1 describes a cylindrical secondary battery in which a wound electrode group is housed in a cylindrical metal battery can (metal can), and leads (conductive components) are welded to the inner surface of a lid (sealing body) that closes the opening of the battery can and to the upper surface of an upper current collector plate (current collecting component). The lead has a plate-shaped top portion and a side wall portion that extends diagonally downward from the outer periphery of the top portion. Slits are formed in the side wall portion vertically from the lower end at intervals around the circumference. The lower end of the side wall portion is bent radially outward. This allows for easy and reliable welding of the upper current collector plate and the lead with an appropriate pressure, and is said to result in a battery with low resistance and excellent output characteristics.

[0004] Japanese Patent Application Laid-Open No. 2006-331993

[0005] In the configuration described in Patent Document 1, when the conductive component is placed on the current collecting component and then pressure is applied to bring the sealing body closer to the current collecting component to crimp the conductive component and the sealing body together, the conductive component may not be able to fully absorb variations in height between the current collecting component and the sealing body in the circumferential direction, which raises concerns that a large load may be concentrated on one part of the current collecting component in the circumferential direction and applied to the electrode group.

[0006] The cylindrical secondary battery according to the present disclosure comprises an electrode group in which a positive electrode plate and a negative electrode plate are wound with a separator interposed therebetween, a cylindrical metal can having an opening at one end and containing the electrode group, a current collecting component connected to the electrode group inside the metal can, a sealing body having electrode terminals exposed to the outside and closing the opening, and a conductive component connected to the current collecting component and the sealing body inside the metal can, wherein the conductive component has a central side plate portion along a plane perpendicular to the central axis, inclined portions extending diagonally outward from multiple circumferential positions on the outer periphery of the central side plate portion, and an outer side plate portion connected to the outer periphery ends of each of the multiple inclined portions and having one side connected to the sealing body, and in each of the multiple inclined portions, a thin-walled portion is formed at the connection portion with the central side plate portion, extending to both circumferential ends of the inclined portion and having a thickness smaller than that of the adjacent portions on both sides.

[0007] According to the cylindrical secondary battery according to the present disclosure, when the conductive part and the sealing body are crimped together, it is possible to prevent excessive load from being applied to the electrode group from a portion of the current collecting part in the circumferential direction.

[0008] 2 is an axial cross-sectional view of a cylindrical secondary battery that is an example of an embodiment; FIG. 3 is a perspective view of a conductive part taken out from an obliquely upper side in an example of an embodiment; FIG. 4 is an A-A cross-sectional view of the conductive part shown in FIG. 2; FIG. 5 is a view of the conductive part shown in FIG. 2 from above; FIG. 6 is a perspective view of a cylindrical secondary battery that is another example of an embodiment, of a conductive part taken out from an obliquely upper side;

[0009] Hereinafter, an example of an embodiment of a cylindrical secondary battery according to the present disclosure will be described in detail with reference to the drawings. Note that the cylindrical secondary battery according to the present disclosure is not limited to the embodiment described below.

[0010] In the following, an example will be shown in which the cylindrical secondary battery is a non-aqueous electrolyte secondary battery, but the present disclosure is not limited to this, and the cylindrical secondary battery may also be an aqueous electrolyte secondary battery.

[0011] Fig. 1 is a cross-sectional view of a cylindrical secondary battery 10 according to an embodiment. As shown in Fig. 1, the cylindrical secondary battery 10 is a non-aqueous electrolyte secondary battery having a positive electrode plate 11, a negative electrode plate 12, and a separator 13, and is provided with an electrode group 14 in which the positive electrode plate 11 and the negative electrode plate 12 are wound with the separator 13 interposed therebetween. The cylindrical secondary battery 10 also includes a cylindrical metal can 16 with a bottom that houses the electrode group 14, a sealing body 17 that closes the opening of the metal can 16, an upper current collecting component 50, and a conductive component 60.

[0012] The upper current collecting component 50 is connected to the electrode group 14 as described below. The conductive component 60 connects the upper current collecting component 50 and the sealing body 17 as described below. Furthermore, when the conductive component 60 is placed on the upper current collecting component 50 and then pressure is applied to the sealing body 17 to crimp the conductive component 60 and the sealing body 17 together, the conductive component 60 can absorb variations in height in the circumferential direction between the upper current collecting component 50 and the sealing body 17. This makes it possible to prevent excessive load from being applied to the electrode group 14 from a portion of the upper current collecting component 50 in the circumferential direction. This will be described in detail later.

[0013] The metal can 16 contains a nonaqueous electrolyte together with the electrode group 14. The metal can 16 has a groove 22 formed in its sidewall, and the sealing body 17 is supported by the groove 22 and closes an opening 16a at the top end of the metal can 16. For ease of explanation, the sealing body 17 side of the cylindrical secondary battery 10 is referred to as the top, and the bottom side of the metal can 16 is referred to as the bottom. The metal can 16 is generally made of a metal primarily composed of iron, such as nickel-plated iron, but may also be made of a metal primarily composed of aluminum or other metals. A locally thin-walled portion at the bottom of the metal can can also be formed to form a fragile portion that easily breaks when the internal pressure of the battery increases. In this case, when the internal pressure of the battery increases, the fragile portion breaks, deforming the inside of the fragile portion and pushing down, allowing high-temperature and high-pressure gas inside the battery to be released through the opening formed inside.

[0014] The non-aqueous electrolyte has ion conductivity (e.g., lithium ion conductivity). The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The non-aqueous electrolyte is not limited to a liquid electrolyte (nonaqueous electrolytic solution), and may be a solid electrolyte using a gel polymer or the like. The cylindrical secondary battery 10 is preferably a lithium ion battery. The electrolyte salt may be, for example, LiBF ４ , LiPF ６ Examples of the non-aqueous solvent include esters such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and methyl propionate (MP), ethers, nitriles, amides, and mixed solvents of two or more of these. The non-aqueous solvent may contain a halogen-substituted product in which at least a portion of the hydrogen atoms of these solvents are substituted with halogen atoms such as fluorine.

[0015] Examples of halogen-substituted compounds include fluorinated cyclic carbonates such as fluoroethylene carbonate (FEC), fluorinated chain carbonates, and fluorinated chain carboxylic acid esters such as methyl fluoropropionate (FMP). From the viewpoint of suppressing a decrease in the charge-discharge cycle characteristics of a nonaqueous electrolyte secondary battery or improving input characteristics, the nonaqueous electrolyte preferably contains 5% by mass or more of FEC, and more preferably 5% by mass to 15% by mass of FEC, relative to the mass of the nonaqueous electrolyte.

[0016] Examples of the solid electrolyte include solid or gel polymer electrolytes and inorganic solid electrolytes. 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. Examples of the matrix polymer include a polymer material that absorbs the non-aqueous solvent and gels. Examples of the polymer material include fluororesin, acrylic resin, and polyether resin. Examples of the inorganic solid electrolyte include materials known in all-solid-state lithium ion secondary batteries (e.g., oxide-based solid electrolytes, sulfide-based solid electrolytes, halide-based solid electrolytes, etc.).

[0017] As described above, the electrode group 14 has a wound structure in which the positive electrode plate 11 and the negative electrode plate 12 are spirally wound with the separator 13 interposed therebetween. The positive electrode plate 11, the negative electrode plate 12, and the separator 13 are all long, strip-shaped bodies that are spirally wound and alternately stacked in the radial direction of the electrode group 14. The negative electrode plate 12 is formed to be slightly larger than the positive electrode plate 11 in order to prevent lithium deposition. That is, the negative electrode plate 12 is formed to be longer in both the longitudinal and lateral directions than the positive electrode plate 11. The separator 13 is formed to be at least slightly larger than the positive electrode plate 11, and, for example, two separators 13 are arranged to sandwich the positive electrode plate 11.

[0018] In the electrode group 14, an upper lead-out portion 31 that is longer upward than the remaining longitudinal portion is formed in a longitudinal portion of the positive electrode core 30 that forms the positive electrode plate 11. The upper end of the upper lead-out portion 31 is welded to the lower surface of an upper current collecting component 50 that is arranged above the electrode group 14 inside the metal can 16. The upper current collecting component 50 is formed in a disk shape from metal and has a central hole formed in its center. This electrically connects the upper current collecting component 50 to the positive electrode core 30. The upper current collecting component 50 is electrically connected to the sealing body 17 (described later) via a conductive component 60 (described later).

[0019] Furthermore, in the electrode group 14, the negative electrode core 40 forming the negative electrode plate 12 extends downwardly from the other portion located at the lower end of the electrode group 14. The lower end of the negative electrode core 40 is welded to the upper surface of a lower current collecting part 52 arranged below the electrode group 14. The lower current collecting part 52 has a bottomed lower cylindrical part 54 that bulges downward at the center of a disc part 53, and the lower surface of the lower cylindrical part 54 is welded to the bottom of the metal can 16. In this way, the negative electrode core 40 is electrically connected to the metal can 16, and the metal can 16 serves as a negative electrode terminal.

[0020] The positive electrode plate 11 includes a positive electrode core 30 and a positive electrode mixture layer 33 formed on both sides of the core. The positive electrode core 30 may be a foil of a metal, such as aluminum or an aluminum alloy, that is stable within the potential range of the positive electrode plate 11, or a film with such a metal disposed on the surface. The positive electrode mixture layer 33 preferably contains a positive electrode active material, a conductive agent such as acetylene black, and a binder such as polyvinylidene fluoride (PVdF), and is formed on both sides of the positive electrode core 30. The thickness of the positive electrode mixture layer 33 is, for example, 40 μm or more and 100 μm or less. The positive electrode active material may be, for example, a lithium transition metal composite oxide containing Ni, Co, Mn, Al, or the like.

[0021] The negative electrode plate 12 has a negative electrode core 40 and a negative electrode mixture layer 41 formed on both sides of the negative electrode core 40. The negative electrode core 40 can be made of a foil of a metal, such as copper or a copper alloy, that is stable within the potential range of the negative electrode plate 12, or a film with such a metal disposed on the surface. The negative electrode mixture layer 41 contains a negative electrode active material and a binder such as styrene-butadiene rubber (SBR). The thickness of the negative electrode mixture layer 41 is, for example, 40 μm or more and 100 μm or less. For example, graphite, a Si-containing material, or the like is used as the negative electrode active material.

[0022] A gasket 28 is provided between the metal can 16 and the sealing body 17 to seal the inside of the battery. The metal can 16 has a groove 22 formed, for example, by pressing the side surface from the outside, that supports the sealing body 17. The groove 22 is preferably formed in an annular shape along the circumferential direction of the metal can 16, and supports the sealing body 17 on its top surface. The top end of the metal can 16 is also bent inward and crimped to the periphery of the sealing body 17. As a result, the sealing body 17 closes the opening 16a of the metal can 16.

[0023] The sealing body 17 is made of metal and has a hat shape with a cylindrical portion 20 at the center of a disk portion 18, which bulges upward and whose upper end is closed by an electrode terminal 19. An upper current collecting component 50 is electrically connected to the underside of the disk portion 18 via a conductive component 60 (described below). This makes the electrode terminal 19 of the sealing body 17 a positive terminal exposed to the outside. It is also possible to form an easily breakable portion that easily breaks when the internal pressure of the battery increases by forming a thin-walled portion having an annular or C-shape on the underside or upper side of the electrode terminal 19. In this case, when the internal pressure of the battery increases, the easily breakable portion breaks, pushing the inside of the easily breakable portion up and deforming, allowing high-temperature and high-pressure gas inside the battery to be released through an opening formed inside.

[0024] At the upper end of the metal can 16, a negative electrode external terminal 70 is fitted and connected around the entire outer surface of a bent portion 16b, which is bent inward from the outer peripheral end of the upper surface of the inner portion of the grooved portion 22. The negative electrode external terminal 70 is made of metal and has a generally L-shaped cross section, including a cylindrical portion 71 and a flange-like disk portion 72 provided at the upper end of the cylindrical portion 71. The lower end of the cylindrical portion 71 is engaged with the outer peripheral end of the upper surface of the inner portion of the grooved portion by an inwardly protruding engaging portion. The lower surface of the disk portion 72 may be welded to the upper surface, which is the outer surface of the bent portion 16b of the metal can 16, around the entire circumference. An outer insulating part 74 is disposed between the negative electrode external terminal 70 and the upper surface of the disk portion 18 and the outer peripheral surface of the cylindrical portion 20 of the sealing body 17, thereby providing insulation between the sealing body 17 and the negative electrode external terminal 70. As a result, a negative electrode external terminal 70 is disposed around the cylindrical portion 20 of the sealing body 17 at the top of the cylindrical secondary battery 10. An external negative electrode lead (not shown) is welded to the negative electrode external terminal 70. An external positive electrode lead (not shown) is welded to the upper end of the sealing body 17. As a result, electrical components for extracting power can be connected to both the positive and negative electrodes from above the cylindrical secondary battery 10.

[0025] Furthermore, an insulating component 90 made of an insulating material such as resin is disposed inside the metal can 16 between the upper end of the electrode group 14 and the upper current collecting component 50 and the metal can 16. The insulating component 90 functions to provide insulation between the upper end of the electrode group 14 and the upper current collecting component 50 and the metal can 16, and also functions as a backup member that suppresses downward deformation of the conductive component 60, which will be described later.

[0026] The insulating component 90 has an inner circular plate portion 91 and an outer circular plate portion 93 connected by an inclined cylindrical portion 94. The inner circular plate portion 91 is positioned above the outer circular plate portion 93. The outer circular plate portion 93 is placed on the upper end of the electrode group 14 and is positioned between the electrode group 14 and the lower end of the grooved portion 22 of the metal can 16. The inner circular plate portion 91 is placed on the upper end of the outer periphery of the upper current collecting component 50, and its inner end faces the lower side, which is the electrode group side, of the outermost periphery of the conductive component 60 (described below). The inner end of the inner circular plate portion 91 is formed with an annular protrusion 92, which has a rectangular cross-section and is continuous around the entire circumference, protruding upward. The upper end of the annular protrusion 92 contacts the lower surface of the outermost periphery of the conductive component 60. The function of the insulating component 90 as a backup member will be described in detail later.

[0027] The configuration of the conductive component 60 will be described in detail below with reference to Figures 1, 2, and 3. Figure 2 is a perspective view of the conductive component 60 removed from the cylindrical secondary battery 10 and viewed obliquely from above. Figure 3 is a cross-sectional view of the conductive component 60 taken along line A-A. Figure 4 is a view of the conductive component 60 viewed from above.

[0028] As described above, the conductive part 60 is electrically connected to the upper current collecting part 50 and the sealing body 17. For this purpose, the lower end surface of the conductive part 60 is connected by welding to the upper surface of the upper current collecting part 50. Furthermore, the upper end surface of the conductive part 60 is crimped to the lower surface of the disk part 18 of the sealing body 17, and then welded to the lower surface of the disk part 18.

[0029] The conductive component 60 is made of a metal plate and includes a circular central side plate portion 61 provided at the radially inner end portion and a plurality of inclined portions 62 extending radially from multiple circumferential positions on the outer periphery of the central side plate portion 61 and obliquely outward toward the upper side corresponding to the upper end of the cylindrical secondary battery 10. In FIG. 2 , the conductive component 60 includes four inclined portions 62, but this is not limited thereto; two, three, five or more inclined portions may be provided as long as they are multiple. The conductive component 60 is formed, for example, by pressing a metal plate such as nickel or nickel-plated steel. The conductive component 60 may also be formed from a conductive metal such as copper or aluminum.

[0030] Furthermore, the inclined portions 62 are connected only via the flat central side plate portion 61. The circumferential side surfaces of the inclined portions 62 are not connected to each other via an inclined plate portion inclined with respect to the central axis O1 along the up-down direction. This allows the inclined portions 62 to move without being affected by the movement of the other inclined portions during the above-mentioned crimping. This makes it easy to absorb variations in the circumferential height between the lower surface of the circular plate portion 18 of the sealing body 17 and the upper surface of the upper current collecting component 50.

[0031] Furthermore, the conductive component 60 has an outer peripheral plate 64 that is provided on the outer periphery and connected to the outer peripheral ends of each inclined portion 62. The outer peripheral plate 64 is arc-shaped, and multiple outer peripheral plate 64 are provided so as to be positioned on the same circle and are spaced apart from each other in the circumferential direction. The outer peripheral plate 64 has a larger circumferential width than the inclined portions 62. One side surface of the outer peripheral plate 64, that is, an upper surface, is connected to the lower surface of the circular portion 18 of the sealing body 17. Because the circumferential width of the outer peripheral plate 64 is larger than the circumferential width of the inclined portions 62, even if the height-wise distance between the lower surface of the circular portion 18 of the sealing body 17 and the upper surface of the upper current collecting component 50 changes in the circumferential direction, the wider area of ​​the outer peripheral plate 64 makes it easier for the conductive component 60 to contact the circular portion 18.

[0032] The central side plate portion 61 is a plate-like portion along a plane perpendicular to the central axis O1 along the up-down direction of the conductive component 60. Furthermore, as shown in FIG. 3 , grooves 66, 67 are formed on the lower surface of each of the inclined portions 62 of the conductive component 60 at both ends in the radial direction. The cross-sectional shape of the grooves 66, 67 is generally semicircular, but is not limited thereto and may be V-shaped, rectangular valley-shaped, or the like. The grooves are also not limited thereto and may be flush with the upper surface or may be separated into upper and lower portions.

[0033] The lower groove 66 is formed on the lower surface of the inclined portion 62 at the connection portion with the center side plate 61, and extends to reach both circumferential ends of the inclined portion 62. This groove 66 causes the thin-walled portion 68 to extend to both circumferential ends of the inclined portion 62, making the thin-walled portion 68 thinner than the adjacent portions on either side of the thin-walled portion 68. The thin-walled portion 68 corresponds to a first thin-walled portion. This makes it easier for the inclined portion 62 to bend upward and downward relative to the center side plate 61, making it easier for the outer side plate 64 to move up and down. Therefore, each outer side plate 64 of the conductive component 60 can easily absorb any circumferential height discrepancy between the sealing body 17 and the upper current collecting component 50.

[0034] The upper groove 67 is formed on the lower surface of the inclined portion 62 at the connection portion with the outer peripheral side plate 64 and extends to both circumferential ends of the inclined portion 62. This groove 67 allows the thin-walled portion 69 to extend to both circumferential ends of the inclined portion 62, making the thin-walled portion 69 thinner than the adjacent portions on either side of the thin-walled portion 69. The thin-walled portion 69 corresponds to a second thin-walled portion. This makes the outer peripheral side plate 64 more likely to bend upward and downward around the upper end of the inclined portion 62. Therefore, by contacting the upper end of the annular protrusion 92 of the insulating component 90 with the lower surface of the outer peripheral side plate 64, downward deformation of the conductive component 60 is suppressed, resulting in a synergistic effect of making it easier for the upper surface of the outer peripheral side plate 64 to come into surface contact with the lower surface of the circular plate 18 of the sealing body 17. This effectively prevents the upper corners of the outer peripheral side plate 64 from coming into corner contact with the lower surface of the circular plate 18, resulting in poor welding. In addition, if the insulating part 90 is not in contact with the lower surface of the outer peripheral side plate part 64, the upper groove part 67 and the upper thin part 69 may not be formed.

[0035] Furthermore, the radial side surfaces S1, S2 and the circumferential side surfaces S3, S4 of the four outer peripheral side plates 64 do not contact other components. The four outer peripheral side plates 64 are independent and separate from one another. As a result, as described below, when the lower surface of the central side plate 61 of the conductive part 60 is welded to the upper surface of the upper current collecting part 50 and then the sealing body 17, which is fixed by crimping to the upper end of the metal can 16, is pressed from above to crimp the sealing body 17 to the conductive part 60, the outer peripheral side plates 64 are allowed to move radially and circumferentially. Therefore, as the inclined portions 62 are bent, the outer peripheral side plates 64 move radially and circumferentially as shown by the arrows in FIG. 1 , making it easier for the conductive part 60 to absorb variations in the circumferential height between the upper current collecting part 50 and the sealing body 17.

[0036] 4 , when the conductive component 60 is viewed from one side in the vertical direction, which is one side in the direction of the central axis O1, the valley lines of the grooves 66 that form the thin-walled portions 68 of the conductive component 60 are linear. Therefore, unlike when each valley line is arc-shaped along the shape of the connection between the inclined portions 62 and the central side plate portion 61, the inclined portions 62 are more likely to bend relative to the central side plate portion 61.

[0037] Furthermore, when the conductive component 60 is viewed from one side in the vertical direction, the valley lines of the grooves 67 that form the thin-walled portions 69 of the conductive component 60 are linear. Therefore, unlike when each valley line is arc-shaped along the shape of the connection between the inclined portion 62 and the outer peripheral side plate portion 64, the outer peripheral side plate portion 64 is more likely to bend relative to the inclined portion 62. Note that the grooves 66, 67 may be configured so that the valley lines are arc-shaped.

[0038] When manufacturing the cylindrical secondary battery 10, the lower current collecting element 52 is welded to the upper surface of the bottom of the metal can 16, and then the electrode group 14 and the upper current collecting element 50 above it are housed inside the metal can 16.

[0039] Next, the insulating component 90 and the central plate portion 61 of the conductive component 60 are placed, in that order, on the upper surface of the upper current collecting component 50, and then a nonaqueous electrolyte is poured into the upper opening of the metal can 16 before the upper end of the metal can 16 is bent and crimped. At this time, the central plate portion 61 of the conductive component 60 may be pre-welded to the upper surface of the upper current collecting component 50. The sealing body 17 is then crimped and fixed to the upper end of the metal can 16. In this state, the upper end of the annular protrusion 92 of the insulating component 90 and the lower surface of the outer peripheral plate portion 64 of the conductive component 60 are vertically spaced apart. Furthermore, the upper surface of the outer peripheral plate portion 64 and the lower surface of the disc portion 18 of the sealing body 17 are vertically spaced apart. In this state, the grooved portion 22 is vertically wider than in the state shown in FIG. 1 .

[0040] Then, pressure is applied from above to the sealing body 17 and the upper end of the metal can 16, deforming the grooved portions 22 while crimping the disk portion 18 of the sealing body 17 to each outer peripheral plate portion 64 of the conductive component 60. At this time, the conductive component 60 is easily bent by the thin-walled portions 68 below each inclined portion 62. Furthermore, since other components do not contact both circumferential and radial sides of the outer peripheral plate portion 64, circumferential and radial movement of the outer peripheral plate portion 64 is permitted. Therefore, each outer peripheral plate portion 64 can easily move up and down without being restricted by the movement of other outer peripheral plate portions 64. Therefore, variations in the circumferential height between the upper current collecting component 50 and the sealing body 17 are easily absorbed by the conductive component 60. Therefore, when crimping the conductive component 60 to the sealing body 17, excessive load on the electrode group 14 from a circumferential portion of the upper current collecting component 50 can be prevented.

[0041] After the conductive part 60 and the sealing body 17 have been crimped together in this manner, a welding current is passed between the positive and negative terminals of the cylindrical secondary battery 10, thereby welding the conductive part 60 and the sealing body 17, the negative electrode core 40 of the electrode group 14 and the lower current collecting part 52, and the upper lead-out portion 31 of the electrode group 14 and the upper current collecting part 50. At this time, the upper current collecting part 50 and the center side plate portion 61 of the conductive part 60 may also be welded.

[0042] At this time, a radial gap is formed between the gasket 28 and the radially outer surface S1 of the outer peripheral side plate portion 64 of the conductive component 60, and gaps are also formed on the circumferential outer sides of both circumferential side surfaces of each outer peripheral side plate portion 64. This allows steam generated by the heat during welding to easily escape into these gaps, thereby efficiently preventing holes from being formed in the sealing body 17 due to steam.

[0043] Note that after the cylindrical secondary battery 10 is completed, no radial gap may be formed between the radially outer surface S1 of the outer peripheral side plate portion 64 of the conductive component 60 and the gasket 28, and the radially outer surface S1 may be in contact with the gasket 28. Even in this case, gaps are formed on the circumferential outer sides of both circumferential side surfaces of each outer peripheral side plate portion 64, making it easier for the steam to escape into those gaps. Even in this case, although the effect is less than that of the configuration shown in FIG. 1 , it is possible to efficiently prevent holes from being formed in the sealing body 17 due to steam.

[0044] After the cylindrical secondary battery 10 has been welded as described above, the outer insulating part 74 and the negative electrode external terminal 70 are fixed to the top of the metal can 16 .

[0045] In the above, we have described a case where the outer peripheral side plate portion 64 is arc-shaped and has a larger circumferential width than the inclined portion 62.However, as long as the outer peripheral side plate portion is connected to the outer peripheral end of each inclined portion 62 and its upper surface is connected to the lower surface of the sealing body 17, its circumferential width may be the same as that of the inclined portion 62 and it may be in the form of a plate extending radially.

[0046] 5 is a perspective view of a conductive component 60a in a cylindrical secondary battery according to another embodiment, viewed from diagonally above. In the conductive component 60a of this example, multiple inclined portions 80 connecting the central side plate 61 and the outer side plate 64 extend obliquely upward toward the outer periphery, sloping in a curved manner from multiple positions around the periphery of the central side plate 61 toward one side in the circumferential direction. Grooves are formed at both upper and lower ends of the underside of each inclined portion 80, thereby forming thin-walled portions 81, 82 at both upper and lower ends of each inclined portion.

[0047] 1 to 4 without increasing the outer diameter of the conductive part 60a. Therefore, each inclined portion 80 can be more easily deformed with a smaller force, and the conductive part 60a can more easily absorb variations in the height in the circumferential direction between the upper current collecting part 50 and the sealing body 17. Other configurations and functions of this example are the same as those of the configurations of FIGS. 1 to 4. Note that in the configuration of this example, each inclined portion may be configured to extend upward and diagonally toward the outer periphery while sloping "linearly" from multiple circumferential positions on the outer periphery of the center side plate portion 61 toward one side in the circumferential direction.

[0048] In addition, in the configurations of the above examples, the grooves provided at both the upper and lower ends of each inclined portion 62, 80 are provided on the underside of each inclined portion 62, 80, but the grooves may also be provided on the upper surface of each inclined portion. On the other hand, in order to make it easier to bend the inclined portions 62, 80 and the outer peripheral side plate portion 64 above the center side plate portion 61 and the inclined portions 62, 80 with a small force, it is preferable to provide grooves on the underside of the inclined portions 62, 80 as in the configurations of the above examples. In addition, grooves may be formed on both the upper and lower surfaces of each inclined portion 62, 80 to form thin-walled portions.

[0049] In the above embodiment, the sealing body 17 is formed from a single member, but the sealing body may be formed by joining multiple components. In the above embodiment, the insulating component 90 functions as a backup member, but a resin member separate from the insulating component may be disposed between the upper current collecting component 50 and the outer peripheral side plate 64 of the conductive component 60, 60a as a backup member.

[0050] The present disclosure will be further described by the following embodiments. Configuration 1: A cylindrical secondary battery comprising: an electrode group in which positive and negative electrode plates are wound with a separator interposed therebetween; a cylindrical metal can having an opening at one end and containing the electrode group; a current collecting component connected to the electrode group inside the metal can; a sealing body having electrode terminals exposed to the outside and closing the opening; and a conductive component connected to the current collecting component and the sealing body inside the metal can, wherein the conductive component has a central side plate portion along a plane perpendicular to a central axis, inclined portions extending diagonally outward from multiple circumferential positions on the outer periphery of the central side plate portion, and an outer side plate portion connected to the outer periphery ends of each of the multiple inclined portions and having one side surface connected to the sealing body, and each of the multiple inclined portions has a first thin-walled portion formed at the connection portion with the central side plate portion, the first thin-walled portion extending to reach both circumferential ends of the inclined portion and having a thickness smaller than that of adjacent portions on both sides. Configuration 2: The cylindrical secondary battery according to configuration 1, wherein the outer peripheral side plate portion has a larger circumferential width than the inclined portion.Configuration 3: The cylindrical secondary battery according to claim 2, wherein the radial and circumferential side surfaces of the outer peripheral side plate portion do not contact other members.Configuration 4: The cylindrical secondary battery according to any one of configurations 1 to 3, wherein, when the conductive component is viewed from one side in the direction of the central axis, a valley line forming the first thin-walled portion of the conductive component is straight.Configuration 5: The cylindrical secondary battery according to any one of configurations 1 to 4, further comprising: a resin backup member placed on the sealing body side of the current collecting component so as to face the electrode group side of the outermost peripheral portion of the conductive component. Configuration 6: The cylindrical secondary battery according to configuration 5, wherein each of the plurality of inclined portions has a second thin-walled portion formed at a connection portion with the outer peripheral side plate portion, the second thin-walled portion extending to reach both circumferential ends of the inclined portion and having a thickness smaller than that of adjacent portions on both sides.

[0051] REFERENCE SIGNS LIST 10 Cylindrical secondary battery, 11 Positive electrode plate, 12 Negative electrode plate, 13 Separator, 14 Electrode group, 16 Metal can, 16a Opening, 16b Folded portion, 17 Sealing body, 18 Disk portion, 19 Top plate portion, 20 Cylindrical portion, 22 Grooved portion, 28 Gasket, 30 Positive electrode core, 31 Upper lead-out portion, 33 Positive electrode mixture layer, 40 Negative electrode core, 41 Negative electrode mixture layer, 50 Upper current collecting part, 52 Lower current collecting part, 53 Disk portion, 54 Lower cylindrical portion, 60, 60a Conductive part, 61 Center side plate portion, 62 Inclined portion, 64 Outer peripheral side plate portion, 66, 67 Groove portion, 68, 69 Thin-walled portion, 70 Negative electrode side external terminal, 71 Cylindrical portion, 72 Disk portion, 74 outer insulating part, 80 inclined portion, 81, 82 thin-walled portion, 90 insulating part, 92 annular protrusion.

Claims

1. A cylindrical secondary battery comprising: an electrode group in which positive and negative electrode plates are wound with a separator interposed therebetween; a cylindrical metal can having an opening at one end and containing the electrode group; a current collecting part connected to the electrode group inside the metal can; a sealing body having electrode terminals exposed to the outside and closing the opening; and a conductive part connected to the current collecting part and the sealing body inside the metal can, wherein the conductive part has a central side plate portion along a plane perpendicular to a central axis, inclined portions extending diagonally outward from a plurality of circumferential positions on the outer periphery of the central side plate portion, and an outer periphery side plate portion connected to each of the outer periphery ends of the plurality of inclined portions and having one side surface connected to the sealing body, and each of the plurality of inclined portions has a first thin-walled portion formed at the connection portion with the central side plate portion, the first thin-walled portion extending to reach both circumferential ends of the inclined portion and having a thickness smaller than that of adjacent portions on both sides.

2. A cylindrical secondary battery as claimed in claim 1, wherein the outer peripheral side plate portion has a circumferential width greater than that of the inclined portion.

3. A cylindrical secondary battery as claimed in claim 2, wherein the radial and circumferential sides of the outer peripheral side plate portion are not in contact with other members.

4. A cylindrical secondary battery as claimed in claim 1, wherein when the conductive component is viewed from one side in the direction of the central axis, a valley line forming the first thin-walled portion of the conductive component is straight.

5. A cylindrical secondary battery as claimed in claim 1, further comprising a resin back-up member placed on the sealing body side of the current collecting component so as to face the electrode group side of the outermost periphery of the conductive component.

6. A cylindrical secondary battery as described in claim 5, wherein in each of the plurality of inclined portions, a second thin-walled portion is formed at the connection portion with the outer peripheral side plate portion, the second thin-walled portion extending to reach both circumferential ends of the inclined portion and having a thickness smaller than the adjacent portions on both sides.

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