JPH11297331A - Secondary battery and its current collector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current collector for a secondary battery formed into a thin film, having high open pore rate and moreover formed into an arbitrary pore pattern, and the secondary battery using the collector. SOLUTION: A secondary battery, such as an alkaline secondary battery and a lithium secondary battery, is constituted using a current collector formed as electrolyzed foil provided with a large number of meshed pores 2 of triangular shapes, hexagonal shapes or the like, and having 50 μm or less for film thickness and 10% or more for open pore rate. A fine particulate layer formed by a smaller current density than a forming current density for an electrodeposition layer main body is provided along the separation face of the electrodeposition layer main body of the foil and its electrodeposition growth face.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a current collector used for forming an electrode of a secondary battery. More specifically, the present invention relates to an improvement of a current collector suitable for use as an electrode material of a secondary battery such as an alkaline secondary battery and a lithium secondary battery.

[0002]

2. Description of the Related Art Conventionally, as an electrode of an alkaline secondary battery, a nickel-plated thin steel plate, or a metal current collector such as a nickel foil or a copper foil filled with an active material and applied thereto has been used. Such a current collector is manufactured by, for example, a cladding method in order to increase the surface area in contact with the active material by using the peripheral portion of the mesh hole and to move electrolyte ions existing on both front and back surfaces of the current collector. A large number of mesh holes, such as expanded metal, are formed by inserting fine slits into the metal foil and pulling the metal foil to increase the opening ratio. As described above, the mesh holes formed in the current collector increase the surface area of the current collector, and from the viewpoint of moving electrolyte ions on the front and back of the current collector, it is preferable to increase the porosity. It is known. It is also known that in order to obtain a high-capacity battery in a limited battery capacity, it is better to reduce the thickness of the current collector as much as possible and increase the amount of the active material to be filled.

[0003]

However, in the case of the conventional current collector, if a mesh hole having a high aperture ratio is formed by forming a fine slit in a metal foil and pulling the metal foil, the mesh hole has a sharp angle. Therefore, the tensile strength of the metal foil is insufficient, and there is a limit in increasing the aperture ratio in the production method. Further, there is a limitation in the hole diameter, the pattern of the holes cannot be changed, and above all, there is a disadvantage that a mesh hole cannot be formed in a current collector such as aluminum due to insufficient strength. Further, even if the current collector is formed into a thin film to increase the filling amount of the active material, the current collector cannot be formed into a thin film having a thickness of 70 μm or less by the above-described manufacturing method. It has a disadvantage that it cannot be formed into

An object of the present invention is to solve the above problems, and it is possible to form a thin film with a high porosity.
Moreover, it is an object of the present invention to provide a current collector for a secondary battery that can be configured in an arbitrary opening pattern and a secondary battery using the current collector.

[0005]

According to the present invention, there is provided a current collector for a secondary battery, wherein the current collector is formed as an electrolytic foil having a large number of mesh holes to achieve the above object. . Further, the current collector of the secondary battery according to the present invention is a current collector for a secondary battery, comprising a large number of mesh holes and configured as an electrolytic foil having a thickness of 50 μm or less. The current collector for a secondary battery according to claim 3 is the current collector for a secondary battery according to claim 2, wherein the electrolytic foil is 10 to 45.
It is characterized in that it has a thickness of μm. Further, the current collector of the secondary battery according to claim 4 includes a large number of mesh holes,
A current collector for a secondary battery, wherein the current collector is configured as an electrolytic foil having an aperture ratio of 0% or more. The current collector for a secondary battery according to claim 5 is the current collector for a secondary battery according to claim 4, wherein the porosity of the electrolytic foil is 20 to 70%. According to a sixth aspect of the present invention, there is provided a current collector for a secondary battery according to any one of the first to fifth aspects, wherein the mesh holes have a triangular shape. According to a seventh aspect of the present invention, there is provided a current collector for a secondary battery according to any one of the first to fifth aspects, wherein the mesh holes have a hexagonal shape. The current collector for a secondary battery according to claim 8 is the current collector for a secondary battery according to any one of claims 1 to 7,
A projection piece integrally formed on the periphery of the mesh hole is projected. According to a ninth aspect of the present invention, there is provided a current collector for a secondary battery according to any one of the first to eighth aspects, wherein the reinforcing portion is integrally formed. Further, the current collector of the secondary battery according to claim 10 is the current collector of the secondary battery according to claim 9, wherein the reinforcing portion is obtained by cutting a current collector material. Features. According to an eleventh aspect of the present invention, there is provided a current collector for a secondary battery according to any one of the first to tenth aspects, wherein a lead portion is integrally formed. The current collector of the secondary battery according to claim 12 is:
The current collector for a secondary battery according to any one of claims 1 to 11, wherein a fine particle layer having a current density smaller than a formation current density of the electrodeposited layer main body is provided on the separation surface side of the electrodeposited layer main body of the electrolytic foil. It is characterized by becoming. The current collector for a secondary battery according to claim 13 is the current collector for a secondary battery according to any one of claims 1 to 12, wherein the current collector extends along the electrodeposition growth surface of the electrodeposition layer body of the electrolytic foil. And a fine particle layer having a current density smaller than the formation current density of the electrodeposition layer main body is provided. The current collector for a secondary battery according to claim 14 is the current collector for a secondary battery according to any one of claims 1 to 13, wherein the electrolytic foil is a copper electrolytic foil, a copper alloy electrolytic foil, nickel Electrolytic foil,
Alternatively, it is a nickel alloy electrolytic foil.
In addition, the current collector of the secondary battery according to claim 15 is the same as claim 4.
14. The current collector for a secondary battery according to any one of claims 13 to 13,
The electrolytic foil is a copper electrolytic foil, a copper alloy electrolytic foil, a nickel electrolytic foil, or a nickel alloy electrolytic foil as a core, on both surfaces of which the core is a dissimilar metal, a copper electrolytic foil, a copper alloy electrolytic foil,
Alternatively, it is characterized by providing an aluminum coating by hot-dip plating. A secondary battery according to a sixteenth aspect is a secondary battery using the current collector according to any one of the first to fifteenth aspects as an electrode material.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The current collector of the present invention is formed as an electrolytic foil 1 having a large number of mesh holes 2 as shown in FIG.
By utilizing 0, it is possible to continuously produce an arbitrary thin film having a size of 50 μm or less and an arbitrary opening ratio of 10% or more in an arbitrary pattern. If the film thickness of the electrolytic foil is less than 10 μm, the mechanical strength is insufficient, and it is difficult to peel off from the drum mandrel 22 of the electrolytic mesh foil manufacturing apparatus 20 at the time of manufacturing, and the handleability is deteriorated. The film thickness is
If it exceeds 50 μm, it is too thick as a current collector,
Since the filling amount of the active material is also insufficient, a film having a film thickness of 10 to 45 μm is particularly preferable. The opening ratio of the electrolytic foil is 1
If it is less than 0%, the electrolyte existing on the front and back of the electrolytic foil cannot be moved, and if it exceeds 70%, the mechanical strength is insufficient, and it is difficult to peel off the drum mandrel during manufacturing. 20
Those having an aperture ratio of 70% are particularly preferred. In the electrolytic mesh foil manufacturing apparatus 20, a rotatable stainless steel, titanium, or chrome-plated drum mandrel (cathode) 22 is disposed at the center of an electrolytic tank 21 made of a vinyl chloride resin tank. In the electrolytic cell 21, a plurality of electrodes (anodes) 23 are arranged along the outer peripheral surface of the drum mandrel 22, and seven electrodes 23 are arranged in the illustrated example. In the drawing, reference numeral 24 denotes a feed roll, which continuously winds the electrolytic foil material 10 formed on the outer peripheral surface of the drum mandrel 22.

In particular, if the mesh holes 2 of the electrolytic foil 1 are formed in a triangular shape as shown in FIG. 2 or a hexagonal shape as shown in FIG. Can be arranged at equal intervals, the strength can be configured to be high, the aperture ratio can be increased, and the mesh hole pattern is optimal for forming the electrolytic foil into a thin film. In particular, in the case of a hexagonal shape, since an acute angle portion does not appear in the mesh holes, an optimum mesh hole pattern is obtained.

Further, as shown in FIGS. 4 (a), 4 (b) and 4 (c), a projecting piece 4 is formed integrally with the periphery of the mesh hole 2 of the electrolytic foil 1 and is bent or the like to form a mesh surface. 5A, 5B and 5C, a fluid pressure such as a gas or a liquid is applied to the electrolytic foil 1 thus obtained. As shown in the figure, the projection 4 can be made to project to form a current collector having a three-dimensional structure. The current collector configured as described above is stacked as shown in FIG. 6 or folded back as shown in FIG. 7 to form a current collector having a three-dimensionally higher aperture ratio. You can also.

As described above, the current collector can be formed in an arbitrary pattern. For example, as shown in FIG. 8, the reinforcing portion 5 can be formed integrally, or as shown in FIG. Alternatively, the lead portion 6 can be formed integrally. The reinforcing portion 4 is formed by a current collector material 1 formed along the outer peripheral surface of the drum mandrel 22 as shown by a cutting line in FIG.
Cutting margin 1 when cutting 0 into individual current collectors (electrolytic foils) 1
It is preferable to use the one obtained from No. 1 in order to increase the handling strength of the current collector material. In the drawing, reference numeral 12 denotes an alignment hole of the current collector material 10 with respect to the drum mandrel 22.

The current collector is formed by adjusting the current density of the anode-side electrode 23 so that, for example, as shown in FIG. A fine particle layer 1B having a current density smaller than the current density formed in the main body 1A can be provided. In this case, the brittle electrodeposition layer main body 1A can be reinforced by the fine particle layer 1B, and the handleability during current collector production, electrode production, or battery assembly is improved. Similarly, by using the above-described manufacturing apparatus, as shown in FIG. 12, the current density is smaller than the formation current density of the electrodeposition layer main body 1A along the electrodeposition growth surface 1c of the electrodeposition layer main body 1A of the electrolytic foil 1. A fine particle layer 1C can be provided. Although the electrodeposition layer main body 1A has a structure capable of filling the active material in a close state, it has a disadvantage that it is brittle, but like the fine particle layer 1B, the brittle electrodeposition layer main body 1A has a disadvantage.
A can be reinforced with the fine particle layer 1C, so that the handleability during current collector production, electrode production, or battery assembly is improved.

As described above, the current collector of the present invention is formed as an electrolytic foil by the electrolytic mesh foil manufacturing apparatus.
Electrode material and selection of electrolyte, or combination of electrolytic plating and hot-dip plating multiple times, as copper electrolytic foil, copper alloy electrolytic foil, nickel electrolytic foil, or nickel alloy electrolytic foil, or these electrolytic foils The core body, the core body and dissimilar metals on both sides thereof, copper electrolytic foil, copper alloy electrolytic foil,
Alternatively, it can be simply configured as a current collector provided with aluminum foil by hot-dip plating.

Using the current collector obtained as described above, a current collector having a copper foil or a nickel foil as a core and copper electrolytic foils provided on both surfaces thereof is made of a carbon paste of a graphite intercalation compound. It can be applied to form a negative electrode of a lithium ion secondary battery. In addition, a current collector having a nickel electrolytic foil as a core and an aluminum coating provided on both surfaces thereof by hot-dip aluminum plating is Li
A positive electrode of a lithium ion secondary battery can be formed by applying a paste of CoO ₂ .

[0013] The current collector made of nickel electrolytic foil is
A negative electrode or a positive electrode of a nickel-cadmium storage battery can be formed by filling spherical particles of cadmium hydroxide or by filling particles of nickel oxyhydroxide and nickel hydroxide.

The current collector made of nickel electrolytic foil is
A negative electrode or a positive electrode of a nickel-metal hydride storage battery can be formed by filling a hydrogen storage alloy powder paste or by filling nickel oxyhydroxide and nickel hydroxide fine particles.

Using these electrodes, a lithium-ion secondary battery, a nickel-cadmium battery, a nickel-hydrogen secondary battery and the like can be constructed. In this case, the current collector is turned into a thin film,
In addition, since the aperture ratio can be configured to be high, a compact and high capacity secondary battery can be obtained. In addition, it is optional to include various additives such as a brightener and a plating aid in the electrolytic foil constituting the current collector.

[0016]

Next, a specific embodiment will be described. Example 1 Production of Copper Electrolyte Foil Current Collector Using the electrolytic film production apparatus shown in FIG.
23b, 23c, 23d, 23e, 23f, and 23g were used as copper electrodes, the electrolytic solution was used as a copper sulfate plating bath, and the current density was 5 A /
dm ² , and the electrodeposition was performed for 20 minutes.
A μm copper electrolytic foil was obtained. The mesh pattern shown in FIGS. 1 and 2 had an aperture ratio of 41.2%. Further, the reinforcing portion and the lead portion were also integrally formed. Observation of the obtained copper electrolytic foil current collector revealed that the peeled surface side of the electrodeposited layer main body from the drum mandrel was formed smoothly, and the electrodeposited growth surface side of the electrodeposited layer main body was formed rough. .

(Example 2) Production of a copper electrolytic foil current collector provided with a fine particle layer Next, as in Example 1, except that eight electrodes 23 were used.
a, 23b, 23c, 23d, 23e, 23f, 23g
To 3 A / dm ² , 5 A / dm ² , 5 A / d
m ² , 10 A / dm ² , 10 A / dm ² , 10 A / dm ² ,
Electrodeposition was performed at a current density of 5 A / dm ² and 3 A / dm ² for 20 minutes, and a copper electrolytic foil having a thickness of 30 μm was obtained. Observation of the obtained copper electrolytic foil current collector revealed that a fine particle layer was formed on the side of the peeling surface of the electrodeposited layer main body from the drum mandrel, and that the electrodeposited layer was grown on the electrodeposited growth side of the electrodeposited layer main body. A fine particle layer was formed along the surface. Then, the obtained copper electrolytic foil current collector has a constant current density of 5 A according to the first embodiment.
The mechanical strength was much higher than that obtained by electrodeposition at m / dm ² , and the handleability was excellent.

(Example 3) Manufacture of an aluminum-coated current collector The copper electrolytic foil obtained in Examples 1 and 2 was used as a core, washed with water and dipped in flux, and then dipped in a molten aluminum tank. Excess aluminum was removed, and aluminum coatings of 10 μm each were formed on both surfaces of the copper electrolytic foil by hot-dip aluminum plating.

Example 4 Production of Nickel Electrolytic Foil Current Collector In the same manner as in Example 2, except that the copper electrode was replaced with a nickel electrode, and the copper sulfate plating bath was replaced with a nickel sulfamate bath, and the mixture was heated for 20 minutes. When electrodeposition was performed, a 30 μm-thick nickel-copper electrolytic foil was obtained. Observation of the obtained copper electrolytic foil current collector revealed that a fine particle layer was formed on the peeling surface side of the electrodeposition layer main body from the drum mandrel. Also, a fine particle layer was formed on the electrodeposition growth surface side of the electrodeposition layer body along the electrodeposition growth surface.

[0020]

As described above, according to the present invention, a thin film
In addition, it is possible to provide a current collector for a secondary battery which can be configured to have a high aperture ratio and an arbitrary aperture pattern, and a secondary battery using the current collector.

[Brief description of the drawings]

FIG. 1 is a plan view of a current collector of the present invention.

FIG. 2 is a plan view showing a pattern of mesh holes of the current collector of the present invention.

FIG. 3 is a plan view showing a mesh hole pattern of the current collector of the present invention.

FIGS. 4A, 4B and 4C are plan views showing respective patterns of three-dimensional mesh holes of the current collector of the present invention.

5 (a), 5 (b) and 5 (c) are perspective views showing respective patterns of three-dimensional mesh holes of the current collector of the present invention.

FIG. 6 is a side view showing a stacked state of a current collector having a three-dimensional mesh hole pattern of the present invention.

FIG. 7 is a side view showing a state in which a current collector having a three-dimensional mesh hole pattern according to the present invention is stacked by folding back;

FIG. 8 is a plan view of a current collector provided with a guide section of the present invention.

FIG. 9 is a plan view of a current collector having a lead portion of the present invention.

FIG. 10 is a plan view of a current collector material for obtaining the current collector of the present invention.

FIG. 11 is a diagram schematically showing a cross section of the current collector of the present invention.

FIG. 12 is a diagram schematically showing a cross section of the current collector of the present invention.

FIG. 13 is a configuration diagram of a manufacturing apparatus for manufacturing the current collector of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrolytic coating 1A Electrodeposition layer main body 1B Fine particle layer 1C Fine particle layer 1b Separation surface 1c Electrodeposition growth surface 2 Mesh hole 3 Forming interval (current collection part) 4 Projection piece 5 Reinforcement part 6 Lead part 10 Collector material 11 Cutting margin DESCRIPTION OF SYMBOLS 12 Alignment hole 20 Electrolyzed mesh foil manufacturing apparatus 21 Electrolytic tank 22 Drum mandrel (cathode) 23 Electrode (anode) 24 Feed roll

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01M 10/40 H01M 10/40 Z (72) Inventor Assho Oki 2-9-1-1, Minami Suita, Suita City, Osaka Sumitomo Special Metals Inside Suita Manufacturing Co., Ltd. (72) Inventor Katsuhiro Nakamura 1-12-26 Kashiwada Nishi, Higashi-Osaka City, Osaka Teikoku Aeon Co., Ltd. (72) Keiichi Nisato 3-12 Suwa, Joto-ku, Osaka City, Osaka Prefecture No. 33 Inside Showa Electroplating Co., Ltd.

Claims (16)

[Claims] 1. A current collector for a secondary battery, wherein the current collector is configured as an electrolytic foil having a large number of mesh holes. 2. A current collector for a secondary battery comprising a large number of mesh holes and constituted as an electrolytic foil having a thickness of 50 μm or less. 3. The current collector for a secondary battery according to claim 2, wherein said electrolytic foil has a thickness of 10 to 45 μm. 4. A current collector for a secondary battery, comprising a large number of mesh holes and configured as an electrolytic foil having an aperture ratio of 10% or more. 5. The current collector for a secondary battery according to claim 4, wherein the porosity of the electrolytic foil is 20 to 70%. 6. The current collector for a secondary battery according to claim 1, wherein the mesh holes have a triangular shape. 7. The current collector for a secondary battery according to claim 1, wherein the mesh holes have a hexagonal shape. 8. A method according to claim 1, wherein a projecting piece integrally formed on a peripheral portion of said mesh hole is projected.
The current collector for a secondary battery according to any one of the above. 9. The current collector for a secondary battery according to claim 1, wherein the reinforcing portion is integrally formed. 10. The current collector for a secondary battery according to claim 9, wherein the reinforcing portion is obtained from a margin of a current collector material. 11. The current collector for a secondary battery according to claim 1, wherein the lead portion is formed integrally. 12. The method according to claim 1, wherein a fine particle layer having a current density smaller than the current density of the electrodeposited layer main body is provided on the side of the electrolytic foil where the electrodeposited layer main body is peeled off. 4. The current collector for a secondary battery according to claim 1. 13. The method according to claim 1, wherein a fine particle layer having a current density smaller than a formation current density of the electrodeposited layer main body is provided along an electrodeposition growth surface of the electrodeposited layer main body of the electrolytic foil. The current collector for a secondary battery according to any one of the above. 14. The electrolytic foil is a copper electrolytic foil, a copper alloy electrolytic foil,
The current collector for a secondary battery according to any one of claims 1 to 13, wherein the current collector is a nickel electrolytic foil or a nickel alloy electrolytic foil. 15. The electrolytic foil is a copper electrolytic foil, a copper alloy electrolytic foil,
Nickel electrolytic foil or nickel alloy electrolytic foil as a core body, copper electrolytic foil which is a metal different from the core body, a copper alloy electrolytic foil, or an aluminum coating by hot-dip plating provided on both surfaces. The current collector of a secondary battery according to claim 4, wherein A secondary battery using the current collector according to any one of claims 1 to 15 as an electrode material.