JP2023087895A - Cylindrical battery and method of manufacturing cylindrical battery - Google Patents

Abstract

To provide a cylindrical battery whose resistance is easily reduced and whose mass productivity is easily enhanced.SOLUTION: A cylindrical battery 10 includes: an electrode body 14 in which a positive electrode 11 and a negative electrode 12 are wound with a separator 13 interposed therebetween; a cylindrical outer can 16 with a bottom that houses the electrode body 14; and a current collector plate 60 electrically connected to the negative electrode 12. A cylindrical portion 30 of the outer can 16 has an inner protruding portion 50 that protrudes radially inward toward a bottom plate 68 of the outer can 16 in the axial direction. An outer peripheral surface 60c of the current collecting plate 60 is brought into contact with an inner peripheral surface 50a of the inner protruding portion 50.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to cylindrical batteries and methods of making cylindrical batteries.

A conventional cylindrical battery is shown in FIG. 4 of Patent Document 1. FIG. In this cylindrical battery, a non-coating portion having no negative electrode mixture layer is provided on one axial side of the negative electrode of the electrode body. The non-coated portion is welded to a disk-shaped current collector, and the current collector is welded to the inner bottom of the outer can. In this manner, the negative electrode is electrically connected to the outer can, and the outer can serves as a negative electrode terminal.

JP-A-9-161837

In the cylindrical battery described above, since the non-coated portion of the negative electrode is electrically connected to the outer can via the current collecting plate, the current collecting property is excellent and high discharge can be performed. However, the current collecting plate is welded to the outer can in order to ensure electrical connection of the current collecting plate to the outer can, which increases the resistance of the welded portion. In addition, there is a risk that the cylindrical battery will deteriorate due to spatter generated when the current collecting plate is welded to the outer can, and that the deterioration will reduce the productivity of the battery.

Accordingly, an object of the present disclosure is to provide a cylindrical battery that can easily reduce resistance and can be easily mass-produced.

In order to solve the above problems, a cylindrical battery according to the present disclosure includes an electrode body in which a first electrode and a second electrode are wound with a separator interposed therebetween, a bottomed cylindrical outer can containing the electrode body, a collector plate electrically connected to the first electrode, wherein the cylindrical portion of the outer can has an inner protruding portion that protrudes radially inward toward the bottom plate side of the outer can in the axial direction. , the side surface of the current collecting plate contacts the inner protrusion.

In addition, the method for manufacturing a cylindrical battery according to the present disclosure includes a tubular portion and a bottom plate, and the end portion of the tubular portion on the bottom plate side has an outer protruding portion that protrudes radially outward and is thick. A cylindrical outer can with a bottom is prepared, and the first electrode in the electrode body in which the first electrode and the second electrode are wound with a separator interposed is joined to the current collector plate, and the electrode body is joined The current collecting plate is placed on the bottom side of the outer can, and the outer protrusion is plastically deformed radially inward to form an inner protrusion that protrudes radially inward from the bottom plate side end of the tubular portion. By forming a portion and pressing the side surface of the current collector plate with the inner protruding portion, the current collector plate is constrained to the bottom side inside the outer can.

According to the cylindrical battery according to the present disclosure, it is easy to reduce the resistance, and it is easy to increase the productivity. In addition, according to the method of manufacturing a cylindrical battery according to the present disclosure, it is possible to manufacture a cylindrical battery with low internal resistance and high productivity.

1 is an axial cross-sectional view of a cylindrical battery according to a first embodiment of the present disclosure; FIG. 3 is a perspective view of an electrode body of the cylindrical battery; FIG. FIG. 3 is a plan view of a long negative electrode before being wound as viewed from one side in the thickness direction; 1 is an axial cross-sectional view of a cylindrical battery in the process of being manufactured; FIG. FIG. 4 is an enlarged axial cross-sectional view of the periphery of the outer projecting portion of the bottomed cylindrical outer can in the middle of production. FIG. 4 is an axial cross-sectional view of a cylindrical battery according to a second embodiment of the present disclosure; It is a figure explaining the manufacturing method of the cylindrical battery of 2nd Embodiment. It is a figure explaining the manufacturing method of the cylindrical battery of 2nd Embodiment. 3 is a plan view of the negative electrode of the cylindrical battery of Comparative Example 1. FIG. 3 is an axial cross-sectional view of a cylindrical battery of Comparative Example 1. FIG. 3 is an axial cross-sectional view of a cylindrical battery of Comparative Example 2. FIG.

Hereinafter, embodiments of the cylindrical battery according to the present disclosure will be described in detail with reference to the drawings. Note that the cylindrical battery of the present disclosure may be a primary battery or a secondary battery. Also, a battery using an aqueous electrolyte or a battery using a non-aqueous electrolyte may be used. Non-aqueous electrolyte secondary batteries (lithium ion batteries) using a non-aqueous electrolyte are exemplified below as the cylindrical batteries 10 and 110 of the embodiments, but the cylindrical battery of the present disclosure is not limited to this.

From the beginning, it is assumed that the features of the first and second embodiments and modifications described below will be appropriately combined to construct a new embodiment. Further, in the following embodiments, the same reference numerals are given to the same configurations in the drawings, and redundant explanations are omitted. In addition, a plurality of drawings include schematic diagrams, and the dimensional ratios of length, width, height, etc. of each member do not necessarily match between different drawings. Further, in this specification, the axial (height) side of the sealing member 17 of the cylindrical battery 10 is referred to as "top", and the axial side of the outer can 16 toward the bottom plate 68 is referred to as "bottom". In addition, among the constituent elements described below, constituent elements that are not described in independent claims indicating the highest concept are optional constituent elements and are not essential constituent elements.

(First embodiment)
FIG. 1 is an axial cross-sectional view of a cylindrical battery 10 according to a first embodiment of the present disclosure, and FIG. 2 is a perspective view of an electrode body 14 of the cylindrical battery 10. FIG. FIG. 3 is a plan view of the elongated negative electrode 12 before being wound as viewed from one side in the thickness direction. As shown in FIG. 1, a cylindrical battery 10 includes a wound electrode body 14, a non-aqueous electrolyte (not shown), and a bottomed cylindrical metal outer can containing the electrode body 14 and the non-aqueous electrolyte. 16, and a sealing member 17 that closes the opening of the outer can 16. As shown in FIG. 2, the electrode assembly 14 has a wound structure in which a long positive electrode 11 and a long negative electrode 12 are wound with two long separators 13 interposed therebetween.

The negative electrode 12 constitutes a first electrode, and the positive electrode 11 constitutes a second electrode. The negative electrode 12 is formed with a size one size larger than that of the positive electrode 11 in order to prevent deposition of lithium. That is, the negative electrode 12 is formed longer than the positive electrode 11 in the longitudinal direction and the width direction (transverse direction). Moreover, the two separators 13 are formed to have a dimension slightly larger than that of the positive electrode 11, and are arranged so as to sandwich the positive electrode 11, for example. The separator 13 protrudes above the positive electrode 11 and the negative electrode 12 , and the negative electrode 12 protrudes below the positive electrode 11 and the separator 13 .

As shown in FIGS. 2 and 3 , the negative electrode 12 is formed by winding the negative electrode current collector 40 at the negative electrode current collector exposed portion 41 where the negative electrode mixture layer 42 is not provided, in the longitudinal direction of the long negative electrode 12 . It has an axially lower end from the side end to the end of the winding end. Therefore, as shown in FIG. 2 , the axially lower end portion of the electrode body 14 is composed of the negative electrode current collector exposed portion 41 . The negative electrode 12 may constitute the winding start end of the electrode body 14 . Generally, however, the separator 13 extends beyond the winding start end of the negative electrode 12 , and the winding start end of the separator 13 becomes the winding start end of the electrode body 14 .

The non-aqueous electrolyte contains a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of the non-aqueous solvent include esters, ethers, nitriles, amides, and mixed solvents of two or more thereof. The non-aqueous solvent may contain a halogen-substituted product obtained by substituting at least part of the hydrogen atoms of these solvents with halogen atoms such as fluorine. The non-aqueous electrolyte is not limited to a liquid electrolyte, and may be a solid electrolyte using a gel polymer or the like. A lithium salt such as LiPF ₆ is used as the electrolyte salt.

The positive electrode 11 has a positive electrode current collector and positive electrode mixture layers formed on both sides of the positive electrode current collector. As the positive electrode current collector, a metal foil stable in the potential range of the positive electrode 11, such as aluminum or an aluminum alloy, or a film in which the metal is arranged on the surface layer can be used. The positive electrode mixture layer contains a positive electrode active material, a conductive agent, and a binder. For example, the positive electrode 11 is formed by coating a positive electrode current collector with a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, a binder, and the like, drying the coating film, and compressing the positive electrode mixture layer to form a positive electrode. It can be produced by forming on both sides of the current collector.

The positive electrode active material is mainly composed 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, W, and the like. An example of a preferable lithium-containing metal composite oxide is a composite oxide containing at least one of Ni, Co, Mn and Al.

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

As shown in FIG. 3 , the negative electrode 12 has a negative electrode current collector 40 and negative electrode mixture layers 42 formed on both sides of the negative electrode current collector 40 . For the negative electrode current collector 40, a metal foil such as copper or a copper alloy that is stable in the potential range of the negative electrode 12, a film having the metal on the surface layer, or the like can be used. The negative electrode mixture layer 42 contains a negative electrode active material and a binder. For the negative electrode 12, for example, a negative electrode mixture slurry containing a negative electrode active material, a binder, and the like is applied onto the negative electrode current collector 40, the coating film is dried, and then compressed to form the negative electrode mixture layer 42 as the negative electrode collector. It can be produced by forming on both sides of the electric body 40 .

A carbon material that reversibly absorbs and releases lithium ions is generally used as the negative electrode active material. Preferred carbon materials are graphite such as natural graphite such as flake graphite, massive graphite and earthy graphite, massive artificial graphite and artificial graphite such as graphitized mesophase carbon microbeads. The negative electrode mixture layer 42 may contain a Si material containing silicon (Si) as a negative electrode active material. In addition, a metal other than Si that forms an alloy with lithium, an alloy containing the metal, a compound containing the metal, or the like may be used as the negative electrode active material.

As in the case of the positive electrode 11, the binder contained in the negative electrode mixture layer 42 may be fluorine resin, PAN, polyimide resin, acrylic resin, polyolefin resin, or the like, but preferably styrene-butadiene rubber ( SBR) or its modified form is used. The negative electrode mixture layer may contain, for example, CMC or its salt, polyacrylic acid (PAA) or its salt, polyvinyl alcohol, etc. in addition to SBR or the like.

A porous sheet having ion permeability and insulation is used for the separator 13 . Specific examples of porous sheets include microporous thin films, woven fabrics, and non-woven fabrics. As the material of the separator 13, polyolefin resins such as polyethylene and polypropylene, cellulose, and the like are preferable. The 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 the separator 13 .

As shown in FIG. 1 , a positive electrode lead 20 is joined to the positive electrode 11 . Cylindrical battery 10 has an insulating plate 18 above electrode body 14 . The positive electrode lead 20 extends through the through hole of the insulating plate 18 toward the sealing member 17 . The positive electrode lead 20 is connected to the lower surface of the bottom plate 23 of the sealing member 17 by welding or the like. A terminal cap 27 forming a top plate of the sealing member 17 is electrically connected to the bottom plate 23, and the terminal cap 27 serves as a positive electrode terminal.

In the example shown in FIG. 1, the positive electrode lead 20 is electrically connected to an intermediate portion such as a central portion in the winding direction of the positive electrode current collector. In the example shown in FIG. 1, only one positive lead 20 is used to electrically connect the positive electrode 11 to the terminal cap 27, but the positive electrode may be electrically connected to the terminal cap in any configuration. good too. For example, the positive electrode may be electrically connected to the terminal cap in a multi-lead configuration. Specifically, one side end of a plurality of positive electrode leads is joined to the positive electrode current collector exposed portion of the positive electrode at intervals in the longitudinal direction of the positive electrode by welding or the like, and the other side end of each of the plurality of positive electrode leads is connected. , directly or indirectly through a conductive portion, to the terminal cap. Alternatively, the exposed portion of the positive electrode current collector may be joined to a conductive current collector plate by welding or the like, and the current collector plate may be directly or indirectly joined to the terminal cap via a conductive portion. When adopting this configuration, the current collector plate can be made of, for example, a metal such as aluminum or an aluminum alloy.

The cylindrical battery 10 is provided with a metallic collector plate 60 made of nickel, a nickel alloy, or the like, below the electrode assembly 14 in the axial direction. The current collector plate 60 has a disk shape, and the negative electrode current collector exposed portion 41 of the electrode body 14 is joined to the upper surface 60 a of the current collector plate 60 . Before inserting the electrode assembly 14 into the outer can 16, the upper surface 60a of the current collector plate 60 is pressed against the negative electrode current collector exposed portion 41 forming the lower end portion of the electrode assembly 14 in the axial direction. The lower surface 60b of 60 is irradiated with laser light.

In this way, when the negative electrode current collector exposed portion 41 is pressed against the current collector plate 60 , the portion of the negative electrode current collector exposed portion 41 that is bent and extends along the upper surface 60 a of the current collector plate 60 . By laser-welding 41 a to the upper surface 60 a of the current collector plate 60 , the negative electrode current collector exposed portion 41 can be joined to the current collector plate 60 . Ultrasonic welding or resistance welding may be used to join the negative electrode current collector exposed portion 41 to the current collector plate 60 .

The cylindrical portion 30 of the outer can 16 has an inner protruding portion 50 that protrudes radially inward toward the bottom plate 68 of the outer can 16 in the axial direction. The inner protruding portion 50 is an annular protruding portion that protrudes radially inward along the entire circumference. The outer peripheral surface 60c of the current collector plate 60 contacts the inner peripheral surface 50a of the inner protrusion 50, and a force is applied radially inward from the inner peripheral surface 50a. The current collector plate 60 is stationary with respect to the inner protrusion 50 by static frictional force, and is positioned in the axial direction. The outer can 16 to which the negative electrode current collector exposed portion 41 is electrically connected via the current collector plate 60 constitutes a negative electrode terminal.

It is preferable that the outer peripheral surface 60c of the current collector plate 60 is in contact with the inner peripheral surface 50a of the inner protrusion 50 over the entire circumference, because the current collector plate 60 can be reliably restrained by the inner protrusion 50. FIG. However, even if the outer peripheral surface 60c of the current collecting plate 60 does not contact the inner peripheral surface 50a of the inner projecting portion 50 partially in the circumferential direction due to tolerances of the current collecting plate 60 and the outer can 16 or manufacturing errors. good. The point is that the current collector plate 60 is stationary with respect to the inner projecting portion 50 by static frictional force, and the axial position of the current collector plate 60 is positioned.

The cylindrical battery 10 further includes a resin gasket 28 arranged between the outer can 16 and the sealing member 17 . The sealing member 17 is crimped and fixed to the opening of the outer can 16 via a gasket 28 . Thereby, the internal space of the cylindrical battery 10 is sealed. The gasket 28 is sandwiched between the outer can 16 and the sealing member 17 to insulate the sealing member 17 from the outer can 16 . The gasket 28 has the role of a sealing material for keeping the inside of the battery airtight and the role of an insulating material for insulating the outer can 16 and the sealing body 17 .

The outer can 16 contains the electrode body 14 and the non-aqueous electrolyte, and has a shoulder portion 38 , a grooved portion 34 , a tubular portion 30 and a bottom plate 68 . The grooved portion 34 can be formed, for example, by spinning a portion of the side surface of the outer can 16 radially inward to form an annular depression radially inward. The shoulder portion 38 is formed by bending the upper end portion of the outer can 16 inward toward the peripheral edge portion 45 of the outer can 17 when the sealing member 17 is crimped and fixed to the outer can 16 .

The sealing body 17 has a structure in which a bottom plate 23, a lower valve body 24, an insulating member 25, an upper valve body 26, and a terminal cap 27 are layered in this order from the electrode body 14 side. Each member constituting the sealing member 17 has, for example, a disk shape or a ring shape, and each member except for the insulating member 25 is electrically connected to each other. The bottom plate 23 has at least one through hole 23a. The lower valve body 24 and the upper valve body 26 are connected at their central portions, and an insulating member 25 is interposed between their peripheral edge portions.

When the cylindrical battery 10 generates abnormal heat and the internal pressure of the cylindrical battery 10 rises, the lower valve body 24 deforms and breaks so as to push the upper valve body 26 upward toward the terminal cap 27, thereby separating the lower valve body 24 and the upper valve body. A current path between the valve bodies 26 is cut off. When the internal pressure further increases, the upper valve body 26 is broken, and the gas is discharged from the through hole 27a of the terminal cap 27. As shown in FIG. This gas discharge prevents the cylindrical battery 10 from bursting due to an excessive increase in the internal pressure of the cylindrical battery 10, thereby enhancing the safety of the cylindrical battery 10. FIG.

Next, a method for manufacturing the cylindrical battery 10 will be described. First, referring to FIG. 7, it includes a tubular portion 30' and a bottom plate 68', and the end portion of the tubular portion 30' on the side of the bottom plate 68' has an outer projecting portion 70 projecting radially outward. Then, a cylindrical outer can 16' having a thick wall and a bottom is prepared. In the present embodiment, the outer protruding portion 70 protrudes radially outward over the entire circumference and has an annular structure. This outer can 16' has not been subjected to the above-described spinning process and caulking, and does not have the shoulder portion 38 or the grooved portion 34. As shown in FIG.

Next, referring to FIG. 1, the negative electrode 12 in the electrode body 14 in which the positive electrode 11 and the negative electrode 12 are wound with the separator 13 interposed therebetween is joined to the collector plate 60 by the method described above. Next, the collector plate 60 to which the electrode assembly 14 is joined is placed on the bottom side of the outer can 16'. After that, the above-mentioned spinning processing and crimping are performed, and as shown in FIG. A battery 10' having outer cans 16'' with different values is fabricated.

After that, drawing is performed so that the outer diameter of the outer protruding portion 70 becomes substantially the same as the outer diameter of the cylindrical portion 30''a that does not have the outer protruding portion 70 in the cylindrical portion 30''. conduct. This drawing is performed by moving the drawing portion 81 of the drawing device 80 relative to the cylindrical portion 30 in the axial direction indicated by the arrow A. The throttle portion 81 is an annular member and has a cylindrical inner peripheral surface 81a. The inner diameter of the cylindrical inner peripheral surface 81a is substantially the same as the outer diameter of the cylindrical portion 30''a. Therefore, by performing the squeezing process, the outer protruding portion 70 is plastically deformed inward in the radial direction, so that the outer protruding portion 70 does not exist and the bottom plate of the cylindrical portion 30 (see FIG. 1) can be removed. An inner protrusion 50 that protrudes radially inward can be formed at the end on the 68 (see FIG. 1) side.

Further, referring to FIG. 5, that is, an enlarged axial cross-sectional view of the periphery of the outer projecting portion 70 in the bottomed cylindrical outer can 16'', the inner peripheral surface of the outer projecting portion 70 and the cylindrical portion 30' are shown. The inner peripheral surface of 'a is included in the same cylindrical inner peripheral surface 85 . Further, 2×(t2−t1), which is twice the value obtained by subtracting the radial thickness t1 of the cylindrical portion 30″a from the radial thickness t2 of the outer protruding portion 70, is the inner diameter of the cylindrical inner peripheral surface 85. is larger than the value obtained by subtracting the outer diameter of the current collector plate 60 before joining the negative electrode current collector exposed portion 41 from the above. Therefore, the inner projecting portion 50 can reliably press the outer peripheral surface 60c of the current collector plate 60 (the outer peripheral surface 60c is an example of the side surface of the current collector plate), and the current collector plate 60 can be pushed toward the bottom side of the outer can 16. It can be reliably restrained, and the battery 10 shown in FIG. 1 can be manufactured. The current collector plate 60 is not joined to the outer can 16 by welding or the like, and the current collector plate 60 is not configured integrally with the outer can 16 . The current collector plate 60 is bound to the outer can 16 by static friction.

As described above, the cylindrical battery 10 includes the electrode body 14 in which the positive electrode 11 and the negative electrode 12 are wound with the separator 13 interposed therebetween; and a connected current collector plate 60 . In addition, the cylindrical portion 30 of the outer can 16 has an inner protruding portion 50 that protrudes radially inward toward the bottom plate 68 side of the outer can 16 in the axial direction, and the outer peripheral surface 60c of the current collector plate 60 extends inward. It contacts the inner peripheral surface 50a of the projecting portion 50 .

According to the present disclosure, the current collector plate 60 can be secured to the outer can 16 by static friction, so there is no need to weld the current collector plate 60 to the outer can 16 . Therefore, the welded portion, which is generated when the current collector plate is welded to the outer can and has a large resistance, can be omitted, and as a result, the internal resistance of the battery 10 can be reduced.

Moreover, since no spatter occurs when the current collector plate 60 is fixed to the outer can 16, the battery 10 is not deteriorated by the spatter. Therefore, the quality of the battery 10 can be improved, the yield rate of the battery 10 can be increased, and the mass productivity of the battery 10 can be improved.

Furthermore, the collector plate 60 can be fixed to the outer can 16 simply by plastically deforming the outer can 16'' without using a large-scale welding device.

Alternatively, the inner protrusion 50 may be an annular protrusion that protrudes radially inward along the entire circumference.

According to this configuration, the inner peripheral surface of the inner protrusion 50 can constrain a wide circumferential portion of the side surface of the current collector plate 60 , so that the current collector plate 60 can be fixed to the outer can 16 more reliably.

(Second embodiment)
FIG. 6 is an axial cross-sectional view of a cylindrical battery 110 according to a second embodiment of the present disclosure. The battery 110 of the second embodiment differs from the cylindrical battery 10 of the first embodiment only in that it has a bent portion 161 in which a disk-shaped collector plate 160 is bent. In the second embodiment, the same reference numerals as in the first embodiment are given to the same configurations as in the first embodiment, and the description thereof is omitted. In addition, in the second embodiment, the description of the effects and modifications similar to those of the first embodiment will be omitted.

In FIG. 6 , the first portion 165 of the current collector plate 160 positioned radially outside the bent portion 161 is indicated by hatching different from the second portion 166 of the current collector plate 160 other than the bent portion 161 . . The first portion 165 coincides with the annular outer edge of the current collector plate 160 .

Battery 110 can be produced, for example, by the following method. Specifically, as shown in FIG. 7, as a current collector plate 160′ before being joined to the negative electrode current collector exposed portion 41, at least a part of the outer edge portion is bent toward the first side in the thickness direction. adopt those with Further, the outer diameter of the collector plate 160' is smaller than the inner diameter of the inner peripheral surface of the bottomed cylindrical outer can 16'.

After joining the negative electrode current collector exposing portion 41 of the electrode body 14 to the current collector plate 160' by the same method as in the first embodiment, the tip of the bent portion 170 of the current collector plate 160' is attached to the bottom plate of the outer can 16'. The current collecting plate 160' and the electrode assembly 14 are accommodated in the outer can 16' so as to contact the inner surface of 68'. In this state, the bent portion 170 extends from the radially outer end of the central portion 175 of the collector plate 160' other than the bent portion 170 to the radially outer side of the outer can 16' toward the bottom plate 68' in the axial direction. Extend.

After that, a force F is applied to the electrode body 14 from the upper side in the axial direction to the lower side in the axial direction. As shown in FIG. 7, the positive electrode lead 20 is joined to the positive electrode 11 before housing the collector plate 160' in the outer can 16', and the axial direction of the collector plate 160' side of the electrode body 14 is After placing the insulating plate 18 on the opposite side, the electrode body 14 may be accommodated in the exterior can 16'. Then, an axially downward force F may be applied to the upper surface 18 a of the insulating plate 18 . In this manner, an axial downward force may be applied indirectly to the electrode body 14 via the insulating plate 18 .

By applying a downward axial force to the electrode body 14, a force is applied to the center portion 175 of the collector plate 160' in the axial direction toward the bottom plate 68', and as shown in FIG. The bent portion 170 is plastically deformed so as to extend substantially in the radial direction, thereby fabricating the current collector plate 160 described above. This plastic deformation causes a bent portion 161 in the current collector plate 160 . The bent portion 161 can be identified because it is slightly deformed in comparison with other portions. After that, the outer projecting portion 70 is plastically deformed into the inner projecting portion 50 by the same method as in the first embodiment to fabricate the battery 110 shown in FIG.

According to the second embodiment, the current collecting plate 160' can be accommodated in the outer can 16' while the outer diameter of the current collecting plate 160' is small. can accommodate. Further, by plastically deforming the current collecting plate 160' after the current collecting plate 160' is accommodated in the outer can 16', the outer diameter of the current collecting plate 160 after plastic deformation is equal to the inner peripheral surface of the outer can 16'. , and the radial gap between the inner peripheral surface of the outer can 16' and the outer peripheral surface of the collector plate 160 can be reduced. Therefore, the inner protruding portion 50 formed by plastically deforming the outer protruding portion 70 can apply a large radially inner force to the current collecting plate 160 , and the current collecting plate 160 can be securely fixed to the inner protruding portion 50 .

(Internal resistance confirmation test)
The inventors of the present application produced cylindrical batteries of Comparative Examples 1 and 2 and cylindrical batteries of Examples 1 and 2, and tested each cylindrical battery at 25°C, 0.2C discharge capacity, and AC (Alternating current) Internal resistance (1 kHz) was measured, and AC internal resistance (1 kHz) was measured after performing a storage test at 4.2 V, 60° C., and 20 days.

<Battery of Comparative Example 1>
A negative electrode 212 whose plan view is shown in FIG. 9 was used. Specifically, a negative electrode current collector exposed portion 241 where the negative electrode mixture layer 242 is not provided is formed at the end portion of the negative electrode current collector 240 of the negative electrode 212 on the winding end side in the longitudinal direction. Then, the negative electrode lead 221 was joined to the negative electrode current collector exposed portion 241 . An electrode body 214 was produced by winding the negative electrode 212 together with the positive electrode 11 and two separators 13 . The electrode body 14 was inserted into a bottomed cylindrical outer can 216 , the negative electrode lead 221 was welded to the can bottom, and the positive electrode lead 20 was welded to the sealing member 17 . After pouring the electrolyte, the can opening was crimped through the gasket 28 to obtain a cylindrical battery 210 having an outer diameter of 18 mm, a height of 65 mm, and a capacity of 2000 mAh, the axial cross-sectional view of which is shown in FIG. made. The battery 210 uses a negative electrode lead 221, the separator 13 constitutes the lower end portion of the electrode body 214, and the cylindrical portion 230 is a bottomed cylindrical outer can 216 that does not have an inwardly projecting portion. and that an insulating plate 19 is arranged between the electrode body 214 and the bottom plate 268 of the outer can 216. The battery 210 is different from the battery 10 shown in FIG. It is the same as the battery 10 shown.

<Battery of Comparative Example 2>
A cylindrical battery 310 whose axial cross-sectional view is shown in FIG. 11 was used as a cylindrical battery of Comparative Example 2. Specifically, in comparison with the battery 10 shown in FIG. 1, the only difference is that a bottomed cylindrical outer can 216 in which the cylindrical portion 230 does not have an inward protrusion is used instead of the bottomed cylindrical outer can 16. However, unlike the battery 10 shown in FIG. 1, a cylindrical battery 310 having the same configuration as the battery 10 shown in FIG. 1 was fabricated. The cylindrical battery 310 had an outer diameter of 18 mm, a height of 65 mm and a capacity of 2000 mAh.

<Battery of Example 1>
The cylindrical battery 10 of the first embodiment was used as the cylindrical battery 10 of Example 1. FIG. To briefly explain the configuration again, the current collector plate 60 was welded to the negative electrode current collector exposed portion 41 . A cylindrical outer can 16' with a bottom having a large outer diameter and a constant inner diameter was prepared, and the electrode body 14 was inserted so that the collector plate 60 was in contact with the bottom of the can. The positive electrode lead 20 was connected to the sealing member 17 . After pouring the electrolytic solution, the sealant 17 was crimped to the opening of the can via a gasket 28 . Thereafter, the outer can 16' is subjected to a drawing process to form an inner protruding portion 50 on the bottom side of the outer can 16 to reduce the inner diameter of the bottom side. The electric plate 60 and the outer can 16 were brought into contact with each other. Thus, a cylindrical battery 10 having an outer diameter of 18 mm, a height of 65 mm and a capacity of 2000 mA was produced.

<Battery of Example 2>
The cylindrical battery 110 of the second embodiment was used as the cylindrical battery 110 of Example 2. FIG. Briefly explaining the structure again, a bottomed cylindrical outer can 16' having a large outer diameter at the bottom side and a constant inner diameter, and a current collecting plate 160' made of Ni whose ends are bent to one side. was prepared, and the current collector plate 160' was welded to the negative electrode current collector exposed portion 41 so that the side warped away from the electrode body 14 side faced, and then the electrode body 14 was inserted into the outer can 16'. The electrode assembly 14 was pressed from above to transform the collector plate 160 ′ into a flat collector plate 160 . The positive electrode lead 20 was connected to the sealing body 17, and after the electrolytic solution was injected, the sealing body 17 was crimped to the opening of the can with a gasket 28 interposed therebetween. Thereafter, the outer can 16' is subjected to a drawing process to form an inner protruding portion 50 on the bottom side of the outer can 16 to reduce the inner diameter of the bottom side. The electric plate 160 and the outer can 16 were brought into contact with each other. Thus, a cylindrical battery 110 with an outer diameter of 18 mm, a height of 65 mm, and a capacity of 2000 mA was produced.

[Test results]
The test results are shown in Table 1 below.

According to the test results, substantially the same discharge capacity was obtained in all of the batteries of Comparative Examples 1 and 2 and Examples 1 and 2. Regarding the initial AC internal resistance, the initial AC internal resistance of the battery of Comparative Example 2 is 7.5 mΩ lower than that of the battery of Comparative Example 1, and the initial AC internal resistance of the batteries of Examples 1 and 2 is Compared to the battery of Comparative Example 1, 8 mΩ was pulled. In the battery of Comparative Example 1, current is collected via the negative electrode lead 221 joined to the end of the winding end of the negative electrode 212 . Therefore, in the battery of Comparative Example 1, it is considered that the resistance is increased due to reasons such as the longer current collection path of the charge passing through the winding start side of the negative electrode 212 .

After the storage test, the resistance of the battery of Comparative Example 1 increased by only 2 mΩ compared to the initial stage, while the resistance of the battery of Comparative Example 2 increased by 5 mΩ compared to the initial stage. This is presumably because gas was generated inside the cell during the storage test, the internal pressure increased, and the bottom of the can swelled, reducing the contact area between the bottom of the can and the current collector plate.

On the other hand, in the battery of Example 1, the resistance increased by only 3 mΩ compared to the initial stage, and compared with Comparative Example 2, the increase in resistance could be suppressed. Furthermore, in the battery of Example 2, the resistance increased by only 2 mΩ compared to the initial state, and a result equivalent to that of the battery of Comparative Example 1 in which the negative electrode lead 221 was welded to the bottom of the can was obtained.

The reason why the increase in the internal resistance of the batteries of Examples 1 and 2 could be reduced compared to the increase of the internal resistance of the battery of Comparative Example 2 after the storage test is that the current collector plates 60 and 160 and the outer can 16 The contact area increased by the contact area between the side surfaces, and in the battery of Comparative Example 2, the contact with the bottom surface of the can decreased due to the swelling of the bottom of the can. It is believed that this is because the contact with the side surface of the outer can is stable, and good conduction performance can be maintained. In addition, in the battery of Example 2, the end of the current collector plate 160' on the outer edge side was warped before being inserted into the outer can 16', and was processed so as to be flat after being inserted into the outer can 16'. are doing. Therefore, the current collector plate 160' can be easily inserted into the outer can 16', and the handleability of the current collector plate 160' can be improved. stable contact can also be realized.

(Modification)
The present disclosure is not limited to the above embodiments and modifications thereof, 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 embodiments, the disk-shaped collector plates 60 and 160 are used, and the outer can 16 has the annular inner projecting portion 50 . However, the current collector does not have to have a disk shape. For example, as current collectors, a plate-shaped portion arranged only in the radial center portion of the battery, and a plurality of collectors extending radially from the outer edge portion of the plate-shaped portion in the radial direction and arranged at intervals in the circumferential direction A current collector having a radially extending portion of . Then, the side surface of the current collector plate may be configured by the distal end surfaces of the plurality of radially extending portions. Even in this case, the current collector plate can be fixed to the outer can by bringing the tip surface of each radially extending portion into contact with the radially inner tip surface of the inner projecting portion.

Also, the inner protrusions may not be annular. For example, the inner protrusions may be spaced apart in the circumferential direction and extend radially inward from the cylindrical portion of the outer can. It may consist of a plurality of radially extending protrusions. Even in this case, the current collector plate can be fixed to the outer can by bringing the radially inner end surface of each radially extending projecting portion into contact with the side surface of the current collector plate.

Also, the case where the first electrode is the negative electrode 12 and the second electrode is the positive electrode 11, the terminal cap 27 constitutes the positive terminal, and the outer can 16 constitutes the negative terminal has been described. However, the first electrode may be the positive electrode, the second electrode may be the negative electrode, the terminal cap 27 may constitute the negative terminal, and the outer can may constitute the positive terminal.

10,110 Cylindrical Battery 11 Positive Electrode 12 Negative Electrode 13 Separator 14 Electrode Body 16 Outer Can 17 Sealing Body 18 Insulating Plate 18a Upper Surface of Insulating Plate 20 Positive Electrode Lead 23 Bottom Plate 23a Through Hole 24 Lower valve body 25 Insulating member 26 Upper valve body 27 Terminal cap 27a Through hole 28 Gasket 30 Cylindrical part 30a Cylindrical part 34 Groove part 38 Shoulder part 40 Negative electrode current collector 41 Negative electrode Exposed current collector 42 Negative electrode mixture layer 45 Peripheral edge 50 Inner protrusion 50a Inner peripheral surface of inner protrusion 60,160 Current collector 60a Upper surface of current collector 60b Lower surface of current collector , 60c Outer peripheral surface of collector plate 68 Bottom plate of outer can 70 Outer protrusion 80 Drawing device 81 Drawn portion 81a Cylindrical inner peripheral surface of drawn portion 85 Cylindrical inner peripheral surface 161 Bent portion 165 first portion 166 second portion 170 bend 175 central portion;

Claims (6)

an electrode body in which the first electrode and the second electrode are wound with a separator interposed therebetween;
a cylindrical outer can with a bottom that houses the electrode body;
a collector plate electrically connected to the first electrode;
The cylindrical portion of the outer can has an inner protruding portion that protrudes radially inward toward the bottom plate of the outer can in the axial direction,
A cylindrical battery, wherein a side surface of the current collector plate contacts the inner protrusion. 2. The cylindrical battery according to claim 1, wherein said inner protrusion is an annular protrusion that protrudes radially inward over the entire circumference. 3. The cylindrical battery according to claim 1 or 2, wherein the current collector plate has a bent portion. The first electrode has an elongate current collector and a mixture layer provided on the current collector,
4. The cylindrical battery according to any one of claims 1 to 3, wherein an exposed current collector portion on which said mixture layer is not provided on said current collector is joined to said current collector plate. A bottomed cylindrical outer can including a cylindrical portion and a bottom plate, wherein the end portion of the cylindrical portion on the bottom plate side has an outer protruding portion that protrudes radially outward and is thick. prepare,
joining the first electrode in the electrode body in which the first electrode and the second electrode are wound with a separator interposed to a current collector plate;
disposing the current collector plate to which the electrode body is joined on the bottom side in the outer can;
By plastically deforming the outer protruding portion inward in the radial direction, an inner protruding portion protruding inward in the radial direction is formed at the end portion of the cylindrical portion on the bottom plate side, and the inner protruding portion protrudes inward in the radial direction. A method for manufacturing a cylindrical battery, wherein the side surface of the current collector plate is pressed to constrain the current collector plate to the bottom side of the outer can. At least a part of the outer edge of the current collector has a bent portion that bends to a first side in the thickness direction before the current collector is housed in the outer can;
the electrode body is joined to a second side in the thickness direction of the electrode body;
The current collector plate to which the electrode assembly is joined is arranged in the outer can so that the first side is positioned on the bottom plate side,
Before plastically deforming the outer protruding portion, a force is applied to the electrode body from a side opposite to the bottom plate side in the axial direction of the electrode body, so that the bent portion is deformed to the second side in the thickness direction. 6. The method of manufacturing a cylindrical battery according to claim 5, wherein force is applied to plastically deform the bent portion.

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