JP2001351669A - Take-up spool for strip-shaped member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a take-up spool for taking up a strip-shaped member like an electrode element used for a secondary cell or a capacitor, which does not cause any deviation, loosening, or eccentricity, regardless of fine structure of the electrode accompanied by the enlargement or miniaturization of the size of the electrode. SOLUTION: The basic material of the take-up spool is hard metal and tungsten carbide or hard metal with hard phase grain composed of tungsten carbide and carbide, nitride, or carbonitride of 4a, 5a, 6a group metal of periodic table, and one or more kinds of mutual solid solution of above materials, and iron group metal, as a binder phase. Further, the take-up spool is coated by single or more layers of laminated hard films composed of one or more compounds chosen from carbide, nitride, or oxide of Al, Si, carbon with diamond structure, or diamond. The take-up spool shown by the figure is made of the hard metal of 87.5%WC-1.5%VC-11%Co, and the surface of which is coated with carbon with diamond structure by CVD method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a winding core for winding a belt-like member such as an electrode element used for a secondary battery or a capacitor.

[0002]

2. Description of the Related Art Such an electrode element is formed by laminating one or several kinds of belt-like members. The belt-shaped member is formed into a spiral shape by a winding device having a winding core. For example, a secondary battery represented by a lead storage battery, an alkaline storage battery, or the like includes a button type and a cylindrical type. Cylindrical batteries are
Generally, it has been obtained by spirally winding a positive electrode and a negative electrode such that a separator is interposed therebetween to produce a spiral electrode body, and inserting this into a battery.

After winding the electrode, the core is pulled out. At that time, the coefficient of friction between the core and the inner surface of the electrode is important. If the coefficient of friction is large, the separator made of polyethylene or the like may be damaged.For example, a silicone release agent may be applied to the surface of the core in contact with the separator, or a glass fiber tape may be attached. Reduction of the tension for winding and roughening of the state of the surface of the winding core have been performed. However, in some cases, the winding core may bite the electrode or the electrode may be damaged. JP-A-6-251774 discloses that the surface is coated with carbon or that the winding core is formed of carbon fiber. ing.

[0004] Further, since the thermal conductivity in the battery is better in the length direction than in the radial direction, when the size of the battery is increased, it is necessary to improve the heat radiation required to accompany the increase in capacity. In many cases, the battery will be elongated due to restrictions on the diameter. However, as the electric capacity of the battery increases, the battery becomes elongated in order to increase the volume energy density, and in a cantilever structure, a necessary tension is not applied so that "wrinkles" do not occur to some extent when winding the electrode which is a band-shaped member. Rai. In addition, the weight of the wound electrode itself causes the shaft to bend in a cantilevered thin shaft, which causes eccentricity.

On the other hand, Japanese Patent Application Laid-Open No. 9-92339 discloses a secondary battery characterized in that a winding core is built in an electrode. Further, Japanese Patent Application Laid-Open No. 7-335249
The publication discloses that the winding core is formed in a hollow cylindrical shape and the material is a metal material such as stainless steel, nickel, titanium, and steel.

[0006]

The thermal conductivity in the battery is better in the length direction than in the radial direction. Therefore, when the size of the battery is increased, the heat dissipation required for increasing the capacity is improved. In many cases, the battery is elongated in shape due to restrictions on the cylindrical diameter. Furthermore, as the electric capacity of the battery increases,
In order to increase the volume energy density, the electrode becomes elongated. In the case of the cantilever structure, there is a problem that it is difficult to apply a necessary tension so that "wrinkles" do not occur to some extent in winding the electrode which is a belt-shaped member. In addition, the weight of the wound electrode itself causes the shaft to bend in a cantilevered thin shaft, which causes eccentricity. In contrast, Japanese Patent Application Laid-Open No. 9-92339
Japanese Patent Application Laid-Open Publication No. H11-139,086 discloses a secondary battery characterized by having a winding core built into the electrode. However, it is necessary to change all the battery structure and production process, increase the weight, and limit the battery structure. There was a problem to receive.

Japanese Patent Application Laid-Open No. Hei 7-335249 discloses that a winding core is formed in a hollow cylindrical shape, and stainless steel, nickel,
It is disclosed that a metal material such as titanium and steel is used, but it is difficult to cope with miniaturization because the cross-sectional area of the core is widened by making it cylindrical, and if it is made thinner, it is made of metal Had limited rigidity. Therefore, when the winding core is extended due to the battery shape becoming slender due to the recent increase in capacity, there is a problem that when the cantilever is used, bending due to tension or necessary tension is not applied so that wrinkles do not occur. there were.

If the coefficient of friction between the winding core and the inner surface of the electrode is large when the winding core is pulled out after the winding of the electrode, the separator made of polyethylene or the like is in contact with the separator when it is damaged. In addition to applying a silicone release agent to the core surface, attaching a glass fiber tape, etc., lowering the tension for winding the belt-shaped member or roughening the surface state of the core is performed. I have.
However, the winding core may bite the electrode or the electrode may be damaged.
No. 774 discloses that the surface is coated with carbon or that the winding core is made of carbon fiber, but there is a problem that a desired effect is hardly obtained and the condition is not maintained under a condition where the winding tension is high. .

[0009]

The present inventors have conducted various studies focusing on the need for a structure in which the winding core is elongated along with the increase in capacity and which does not bend even when it is cantilevered. The present invention has been made. Specifically, the core is made of tungsten carbide, or hard phase particles composed of tungsten carbide and at least one of carbides, nitrides, carbonitrides and mutual solid solutions of metals belonging to groups 4a, 5a and 6a of the periodic table. It is characterized in that the iron group metal is a cemented carbide comprising a binder phase.

In addition, tungsten carbide or one of the carbides, nitrides, carbonitrides of tungsten carbide and metals of groups 4a, 5a and 6a of the periodic table and their mutual solid solutions
The base material is a cemented carbide having a hard phase particle composed of at least one species and an iron group metal as a binder phase.
a, 6a element, aluminum, silicon carbide, nitride, oxide and their mutual solid solution, or diamond-like carbon or one or more compounds selected from diamond, or a single layer or two or more layers 0.
By forming a coated cemented carbide by coating a hard film having a thickness of 5 to 20 μm, the mechanical wear resistance and the adhesion resistance to the electrode are further improved.

The core is pulled out after winding the electrode. If the core has a large coefficient of friction between the core and the inner surface of the electrode, the core may bite into the electrode or the electrode may be damaged. On the other hand, the surface of the core is 0.8 S or less.

[0012]

FIG. 1 shows a typical shape of a winding core to which the product of the present invention is applied. This core is made of tungsten carbide, or tungsten carbide and 4a, 5a of the periodic table.
a, a cemented carbide having a hard phase particle composed of at least one of carbides, nitrides, carbonitrides of a group 6a metal and a mutual solid solution thereof and an iron group metal as a binder phase, When high strength is required due to its high and extremely elongated shape, a WC-Co based sintered body is preferable.
Are more preferably fine particles having a particle size of 1.0 μm or less.
Is more preferably 10 to 40%. If adhesion resistance is required depending on the electrode material, use Ni
And the ratio of Ni in the binder phase is 40%
It is preferable to make the above.

When the inner diameter accuracy of the electrode is emphasized and wear resistance is required, tungsten carbide or a carbide of a metal of the group 4a, 5a, or 6a of the periodic table with tungsten carbide,
The base material is a hard phase particle composed of one or more of nitrides, carbonitrides and mutual solid solutions thereof and a cemented carbide having an iron group metal as a binder phase. 6a
A single layer of at least one compound selected from the group consisting of group elements, aluminum, carbides, nitrides, oxides of silicon, and oxides thereof, or diamond-like carbon or diamond; 0.5-20
Abrasion resistance is improved by forming a coated cemented carbide alloy coated with a μm hard film.

The coating on the cemented carbide can be obtained by a process such as plating or thermal spraying, but a vapor phase synthesis method such as a PVD method (physical vapor deposition method) or a CVD method (chemical vapor deposition method) is preferable. Ion plating, arc ion plating, sputtering, vapor deposition, and the like are suitable as the PVD method, and plasma CVD is suitable as the CVD method. Abrasion resistance increases proportionately as the film thickness increases, but the strength tends to decrease and the surface roughness tends to be rough. If the thickness is too small, the desired abrasion resistance cannot be obtained, so 0.5 to 20 μm
And limited. Among them, 0.6 to 7 μm is preferable,
1-4 μm is more preferred.

Further, in order to facilitate the removal after the winding, the surface is mirror-finished to a surface roughness of 0.8S. In the case of the conventional metal, the surface was active, so that the effect of facilitating removal was not obtained even if the surface roughness was smoothed, but the surface of the periodic table 4a, 5a ,
It is a single layer or a laminate of two or more layers of a group 6a element, aluminum, silicon carbide, nitride, oxide and their mutual solid solutions, or one or more compounds selected from diamond-like carbon and diamond. 0.5
In a core made of a sintered body coated with a hard film having a thickness of up to 20 μm, the effect of smoothing the surface roughness is remarkable, and desired characteristics can be obtained by setting it to 0.8 S or less. 0.2S or less is more preferable.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A winding core having the shape shown in FIG.
Invention 1 is made of a cemented carbide having a composition of% WC-1.5% VC-11% Co and a hard phase having an average particle size of the hard phase of 0.8 μm and mirror-finished to a surface roughness of 0.2S. And Inventive product 1 was used as a base material, and diamond-like carbon (hereinafter referred to as DLC)
Was abbreviated to 1 μm by a plasma CVD method to obtain invention product 2. Invention 1 with the same shape made of stainless steel
It was made to have the same surface roughness as that of Comparative Example 1. Comparative product 1 was coated with DLC by 1 μm by a plasma CVD method to obtain comparative product 2. These test articles were evaluated under the following conditions.

Test conditions The electrodes used for the test were prepared as follows. As a positive electrode active material, a mixture obtained by adding a composite oxide of cobalt and lithium as a main component, a binder made of carbon powder and an epoxy resin in a total amount of 10%, and further dispersing the mixture in a solvent to form a paste. After coating and drying on both sides, molding was performed to produce a positive electrode. Next, after oxygen-crosslinking the coal tar, a heat treatment is performed at 1300 K in an inert gas to obtain amorphous carbon, which is further pulverized, mixed with a 10% epoxy resin binder, dispersed in a solvent, and pasted. After coating and drying on both sides of a strip-shaped copper foil, a negative electrode was produced by molding. In addition, a microporous polypropylene film was used as an insulating separator between the positive electrode and the negative electrode. A positive electrode and a negative electrode together with a separator were sandwiched between slits of a winding core having a slit structure shown in FIG. Width 1
Table 1 shows the results of measuring the defective rate when the electrode having a diameter of 20 mm and an outer diameter of 18 mm was wound by the above-described manufacturing method to produce 50 electrodes, and the pulling force after the winding.

Table 1

[0019]

As shown in the examples, even in the case of a long and thin cantilever, excellent characteristics were exhibited. This is due to the fact that the rigidity has been extremely improved, and the bending during winding has been suppressed.
Since the product of the present invention also has a lower extraction force than the comparative product, the deformation of the electrode at the time of extraction is suppressed, so that the roundness is improved and the defect rate is reduced.

[Brief description of the drawings]

FIG. 1 Core

FIG. 2 is a sectional view

Claims (3)

[Claims] 1. Hard phase particles comprising tungsten carbide or at least one of carbides, nitrides, carbonitrides of tungsten carbide and metals of groups 4a, 5a and 6a of the periodic table and mutual solid solutions thereof, and iron group metal Core for winding a band-shaped member made of a cemented carbide having a binder phase of 2. Hard phase particles comprising tungsten carbide or at least one of carbides, nitrides, carbonitrides of tungsten carbide and metals of groups 4a, 5a and 6a of the periodic table and their mutual solid solutions, and iron group metal Is used as a base material, and the base material surface has a group 4a, 5a, or 6a element of the periodic table, aluminum, silicon carbide, nitride, oxide and their mutual solid solution, or diamond-like. A film thickness of 0.5 to 2 which is a single layer composed of one or more compounds selected from carbon and diamond or a multilayer composed of two or more layers
A core for winding a belt-shaped member made of a coated cemented carbide coated with a 0 μm hard film 3. The method according to claim 1, wherein the surface roughness of the winding core is 0.8 S or less represented by the JIS standard.
Item 3. The winding core for winding a belt-shaped member according to Item 2 or 2.