WO2025182677A1 - Sealed battery - Google Patents

Abstract

Provided is a battery (10) comprising an electrode body (14) in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, an electrolyte, a bottomed cylindrical outer can (20) that accommodates the electrode body (14) and the electrolyte, a sealing body (21) that closes the open end (20B) of the outer can (20), and an annular gasket (19) that is interposed between the outer can (20) and the sealing body (21), wherein grooves (19C) that connect the radially inner side and the radially outer side are formed on the bottom surface of the gasket (19).

Description

sealed battery

This disclosure relates to a sealed battery.

Cylindrical batteries are well known as sealed batteries. Cylindrical batteries have, for example, an electrode assembly, a cylindrical outer can with a bottom that houses the electrode assembly, a sealing body that closes the open end of the outer can, and a gasket that is provided between the outer can and the sealing body (see, for example, Patent Document 1).

In the manufacturing process for cylindrical batteries, the electrode body is inserted into the outer can, an upper insulating plate is placed above the electrode body, a groove is machined into the upper side of the upper insulating plate at the open end of the outer can to form a grooved portion, a gasket is inserted into the grooved portion, electrolyte is injected into the outer can, and the sealing body is crimped and fixed to the open end of the outer can via the gasket.

Japanese Patent Application Laid-Open No. 2000-306557

In the manufacturing process for the cylindrical battery described above, when processing the grooves in the open end of the outer can, the outer can is rotated at high speed and a jig is pressed against the open end to form the groove. At this time, the jig presses downward on the radially outer side of the upper insulating plate, deforming the upper insulating plate so that the radially inner side of the upper insulating plate protrudes upward, and when the gasket is inserted, the gasket and upper insulating plate may come into close contact. If electrolyte is injected in this state, the electrolyte will not flow between the upper insulating plate and the gasket, which may reduce the fluidity of the electrolyte radially outward of the outer can.

If the fluidity of the electrolyte toward the radially outward direction of the outer can decreases, the electrolyte level on the radially inner side of the outer can may exceed the gasket, causing the electrolyte to creep up from the gasket and become trapped between components, such as between the positive electrode cap and positive electrode current collector plate, or between the positive electrode current collector plate and positive electrode tab. In this case, there is a risk of a decrease in welding quality when welding the positive electrode cap and positive electrode current collector plate.

The present disclosure therefore aims to provide a sealed battery that can improve the fluidity of the electrolyte solution radially outward from the outer can during the manufacturing process.

The sealed battery disclosed herein is a sealed battery comprising an electrode assembly in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, an electrolyte, a cylindrical outer can with a bottom that contains the electrode assembly and the electrolyte, a sealing body that closes the open end of the outer can, and an annular gasket that is interposed between the outer can and the sealing body, and is characterized in that a groove that connects the radially inner side and the radially outer side is formed in the bottom surface of the gasket.

The sealed battery disclosed herein can improve the fluidity of the electrolyte solution radially outward from the outer can during the manufacturing process.

1 is an axial cross-sectional view showing a sealed battery according to an embodiment of the present invention; FIG. 2 is a perspective view of a gasket according to an embodiment, as viewed from the bottom side. 1 is a flowchart of a manufacturing process for a sealed battery according to an embodiment. FIG. 4 is a schematic diagram showing the grooving step of FIG. 3 . FIG. 4 is a schematic diagram showing the liquid injection step of FIG. 3 .

Below, an example of an embodiment of the present disclosure is described in detail. In the following description, specific shapes, materials, directions, numerical values, etc. are examples intended to facilitate understanding of the present disclosure, and can be modified as appropriate to suit the application, purpose, specifications, etc.

[Sealed battery]
A battery 10 as an example of an embodiment will be described with reference to FIG.

Battery 10, which serves as a sealed battery, is a nonaqueous electrolyte secondary battery (lithium ion battery) that uses a nonaqueous electrolyte. However, the sealed battery of the present disclosure is not limited to the nonaqueous electrolyte secondary battery of this embodiment, and may be a primary battery or a battery that uses an aqueous electrolyte. Battery 10 is also a cylindrical battery. However, the sealed battery of the present disclosure is not limited to the cylindrical battery of this embodiment, and may be a prismatic battery, button battery, or coin battery.

In the following, each component may be described using the axial, radial, and circumferential directions of the battery 10. Furthermore, the sealing body 21 side in the axial direction (height direction) of the battery 10 may be referred to as "upper," and the bottom 20A side of the outer can 20 in the axial direction may be referred to as "lower."

The battery 10 comprises an electrode assembly 14, an electrolyte (not shown), and an outer can 20 that houses the electrode assembly 14 and the electrolyte. The electrode assembly 14 comprises a positive electrode, a negative electrode, and a separator, and has a wound structure in which the positive electrode and negative electrode are wound in a spiral shape with the separator interposed between them. The outer can 20 has a cylindrical shape with a bottom and an open top, and the opening of the outer can 20 is closed by a sealing body 21.

The positive electrode comprises a positive electrode current collector and a positive electrode composite layer formed on at least one surface of the current collector. The positive electrode current collector can be a foil of a metal stable within the potential range of the positive electrode, such as aluminum or an aluminum alloy, or a film with such a metal disposed on the surface. The positive electrode composite layer contains a positive electrode active material, a conductive material such as acetylene black, and a binder such as polyvinylidene fluoride, and is preferably formed on both surfaces of the positive electrode current collector. For example, a lithium-containing transition metal composite oxide is used as the positive electrode active material. The positive electrode can be manufactured by applying a positive electrode composite slurry containing a positive electrode active material, a conductive material, and a binder to the positive electrode current collector, drying the coating, and then compressing the coating to form a positive electrode composite layer on both surfaces of the positive electrode current collector.

The negative electrode comprises a negative electrode current collector and a negative electrode composite layer formed on at least one side of the current collector. The negative electrode current collector can be a foil of a metal stable within the potential range of the negative electrode, such as copper or a copper alloy, or a film with such a metal disposed on its surface. The negative electrode composite layer contains a negative electrode active material and a binder such as styrene-butadiene rubber (SBR), and is preferably formed on both sides of the negative electrode current collector. Examples of negative electrode active materials include graphite and silicon-containing compounds. The negative electrode can be manufactured by applying a negative electrode composite slurry containing a negative electrode active material and a binder to the negative electrode current collector, drying the coating, and then rolling the coating to form a negative electrode composite layer on both sides of the current collector.

For example, a porous sheet with ion permeability and insulating properties is used as the separator. Specific examples of porous sheets include microporous thin films, woven fabrics, and nonwoven fabrics. Suitable materials for the separator include olefin resins such as polyethylene and polypropylene, and cellulose. The separator may also be a laminate having a cellulose fiber layer and a thermoplastic resin fiber layer such as an olefin resin. It may also be a multilayer separator including a polyethylene layer and a polypropylene layer, and the surface of the separator may be coated with a material such as aramid resin or ceramic.

For example, a non-aqueous electrolyte is used as the electrolyte. The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. For example, esters, ethers, nitriles, amides, and mixed solvents of two or more of these may be used as the non-aqueous solvent. The non-aqueous solvent may contain a halogen-substituted compound in which at least a portion of the hydrogen atoms in these solvents are substituted with halogen atoms such as fluorine. The non-aqueous electrolyte is not limited to a liquid electrolyte, but may also be a solid electrolyte. For example, a lithium salt such as _LiPF6 is used as the electrolyte salt. The type of electrolyte is not particularly limited, and may also be an aqueous electrolyte.

The battery 10 comprises an upper insulating plate 17 and a lower insulating plate 18, respectively disposed above and below the electrode body 14. In the example shown in FIG. 1, the positive electrode lead 15 attached to the positive electrode passes through a through-hole in the upper insulating plate 17 and extends toward the sealing body 21, while the negative electrode lead attached to the negative electrode passes outside the lower insulating plate 18 and extends toward the bottom 20A of the outer can 20. The positive electrode lead 15 is connected by welding or the like to the positive electrode current collector plate 22, which is the bottom plate of the sealing body 21, and the cap 26, which is the top plate of the sealing body 21 and is electrically connected to the positive electrode current collector plate 22, serves as the positive electrode external terminal. The negative electrode lead is connected by welding or the like to the inner surface of the bottom 20A of the outer can 20, which serves as the negative electrode external terminal.

The outer can 20 is a cylindrical metal container with a bottom. A gasket 19 is provided between the outer can 20 and the sealing body 21, ensuring airtightness inside the battery 10. Details of the gasket 19 will be described later. Near the open end 20B of the outer can 20, a grooved portion 20C is formed, with part of the side surface protruding inward, to support the sealing body 21. The grooved portion 20C is preferably formed in an annular shape along the circumferential direction of the outer can 20, and supports the sealing body 21 on its upper surface. The sealing body 21, supported by the grooved portion 20C, is fixed to the outer can 20 by the open end 20B of the outer can 20, which is crimped to the sealing body 21.

A thin, easily breakable portion 20D is formed on the bottom 20A of the outer can 20. The easily breakable portion 20D is formed, for example, by stamping a circle or C-shape on the underside of the bottom 20A. By providing the easily breakable portion 20D on the bottom 20A, if the battery 10 generates abnormal heat, the easily breakable portion 20D 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 sealing body 21 has a structure in which, from the electrode body 14 side, a positive electrode current collector plate 22 and a cap 26 are stacked. Each member constituting the sealing body 21 is, for example, disk-shaped or ring-shaped, and is electrically connected to each other.

[gasket]
The gasket 19 will be described with reference to FIG.

As described above, the gasket 19 is a member interposed between the outer can 20 and the sealing body 21. The gasket 19 ensures that the interior of the battery 10 is sealed. The gasket 19 also ensures insulation between the outer can 20 and the sealing body 21. Furthermore, the groove portion 19C of the gasket 19, which will be described in detail later, improves the flow of the electrolyte radially outward from the outer can 20 during the manufacturing process of the battery 10.

The gasket 19 is made of an elastic insulating resin. Examples of elastic insulating resins that may be used include polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), perfluoroalkoxy fluororesin (PFA), nylon, etc.

The gasket 19 is formed in an annular shape. It has a ring-shaped main body 19A, a wall portion 19B formed by protruding upward from the outer periphery (radial outer end) of the main body 19A, and a groove portion 19C formed on the bottom surface of the main body 19A, each of which will be described in detail below.

The main body 19A is interposed between the positive electrode current collector plate 22 and the upper insulating plate 17. An opening is formed in the center of the main body 19A for injecting electrolyte. The wall portion 19B is interposed between the outer can 20 and the sealing body 21. After the sealing body 21 is crimped and fixed to the open end 20B of the outer can 20, the wall portion 19B is formed into a C-shape in cross section when viewed from the circumferential direction.

As described above, groove portion 19C is formed on the bottom surface of main body 19A. Groove portion 19C is formed so as to connect the radially inner side with the radially outer side. Multiple groove portions 19C are formed, and each of the multiple groove portions 19C is formed radially at equal intervals in the circumferential direction. The cross-sectional shape of groove portion 19C as viewed from the radial direction may be rectangular, square, trapezoidal, U-shaped, V-shaped, etc. Furthermore, the cross-sectional shape of groove portion 19C as viewed from the radial direction may be formed so as to become larger radially outward. This can further improve the fluidity of the electrolyte, as will be described in detail below.

As will be described in detail below, groove portion 19C makes it easier for the electrolyte to flow radially outward of outer can 20 when the electrolyte is injected during the manufacturing process of battery 10. This improves the fluidity of the electrolyte radially outward of outer can 20 during the manufacturing process of battery 10. As a result, the reliability of battery 10 can be improved.

[Sealed battery manufacturing process]
The manufacturing process of the battery 10 will be described with reference to Figures 3 to 5. In the following, Figures 1 and 2 may be referred to as appropriate.

As shown in FIG. 3, in step S11, the positive electrode and negative electrode are spirally wound with a separator interposed therebetween to produce the electrode assembly 14. In step S12, the electrode assembly 14, together with the lower insulating plate 18, is inserted into a cylindrical outer can 20 with a bottom made by drawing a steel plate. In step S13, the inner surface of the bottom 20A of the outer can 20 is welded to the negative electrode lead.

In step S14, the upper insulating plate 17 is inserted into the outer can 20. In step S15, a groove is machined into the upper side of the upper insulating plate 17 at the open end 20B of the outer can 20 to form a grooved portion 20C. In step S16, a gasket 19 is inserted into the grooved portion 20C. In step S17, the positive electrode current collector plate 22 and the positive electrode lead 15 are welded together. In step S18, an electrolyte is injected into the outer can 20.

Here, as shown in FIG. 4, in step S15 described above, the outer can 20 is rotated at high speed and a jig J is pressed against the open end 20B to form the grooved portion 20C. At this time, the jig J presses the radially outer side of the upper insulating plate 17 downward, which may deform the upper insulating plate 17 so that the radially inner side of the upper insulating plate 17 protrudes upward.

In this case, when the gasket 19 is inserted into the grooved portion 20C in step S16, the upper insulating plate 17 and the gasket 19 come into close contact with each other (see Figure 5). In this state, if electrolyte is injected into the outer can 20 in step S18, the electrolyte may not flow between the upper insulating plate 17 and the gasket 19, and the fluidity of the electrolyte radially outward from the outer can 20 may decrease.

If the fluidity of the electrolyte toward the radially outward direction of the outer can 20 decreases, the electrolyte level will exceed the gasket 19 on the radially inner side of the outer can 20, causing the electrolyte to creep up from the gasket 19 and become interposed between the positive electrode current collector 22 and the positive electrode lead 15. In this case, there is a risk of a decrease in welding quality when welding the positive electrode current collector 22 and the positive electrode lead 15 together in step S17, for example.

As described above, by forming a groove 19C in the bottom surface of the gasket 19 that connects the radially inner side to the radially outer side as shown in FIG. 5, even if the electrolyte is injected into the outer can 20 with the upper insulating plate 17 and the gasket 19 in close contact, the electrolyte solution will be more likely to flow radially outward from the outer can 20 (arrow in FIG. 5). This improves the fluidity of the electrolyte solution radially outward from the outer can 20 during the manufacturing process of the battery 10. As a result, the reliability of the battery 10 can be improved.

As shown in FIG. 3 again, in step S19, the sealing body 21 is inserted into the open end 20B of the outer can 20. In step S20, the sealing body 21 is crimped and fixed to the open end 20B of the outer can 20 via the gasket 19.

Note that this disclosure is not limited to the above-described embodiments and their variations, and various modifications and improvements are possible within the scope of the claims of this application.

10 Battery (sealed battery), 14 Electrode body, 15 Positive electrode lead, 16 Negative electrode lead, 17 Upper insulating plate, 18 Lower insulating plate, 19 Gasket, 19A Body, 19B Wall portion, 19C Groove portion, 20 Outer can, 20A Bottom portion, 20B Cylindrical portion, 20C Grooved portion, 20D Easy-to-break portion, 21 Sealing body, 22 Positive electrode current collector plate, 26 Cap

Claims (2)

A sealed battery comprising: an electrode assembly in which a positive electrode and a negative electrode are wound with a separator interposed therebetween; an electrolytic solution; a cylindrical outer can with a bottom that contains the electrode assembly and the electrolytic solution; a sealing body that closes an open end of the outer can; and an annular gasket that is interposed between the outer can and the sealing body,
A groove portion communicating the radially inner side and the radially outer side is formed on the bottom surface of the gasket.
Sealed battery. The sealed battery according to claim 1,
The groove portion is formed in plurality,
The plurality of grooves are formed radially.
Sealed battery.