WO2013018473A1

WO2013018473A1 - Metal foil with coating layer and method for producing same, secondary cell electrode and method for producing same, and lithium ion secondary cell

Info

Publication number: WO2013018473A1
Application number: PCT/JP2012/066439
Authority: WO
Inventors: 了一小黒; 直文徳原; 勇曹
Original assignee: 古河電気工業株式会社
Priority date: 2011-07-29
Filing date: 2012-06-27
Publication date: 2013-02-07
Also published as: KR20140051375A; TW201320454A; JPWO2013018473A1; JP5435519B2; CN103718346A

Abstract

Provided is an electrolytic copper foil for use in a collector having consistent Li secondary cell characteristics, that does not give rise to wrinkles in the collector used in an Li secondary cell, that does not rupture, and that has high cohesion to the active material and the collector. This metal foil (copper foil) with a coating layer is furnished with the coating layer on at least one side of an untreated metal film, the coating layer containing free metal particles.

Description

Metal foil with coating layer and method for producing the same, electrode for secondary battery and method for producing the same, and lithium ion secondary battery

The present invention relates to a metal foil with a coating layer that is particularly excellent as an electrode for a lithium ion secondary battery.
Moreover, this invention relates to the electrode for secondary batteries using the said metal foil with a coating layer, and the lithium ion secondary battery using this electrode.

Lithium ion secondary batteries are used as an indispensable power source for mobile phones, mobile terminals, laptop computers and the like. Copper foil is generally used for the current collector on the negative electrode side of the lithium ion secondary battery. In the negative electrode current collector, carbon particles are applied as a negative electrode active material layer on the surface of a copper foil having a smooth front and back, and further pressed to form a negative electrode.

As a negative electrode current collector for a lithium ion secondary battery, a copper foil having a small difference in surface roughness between the front and back surfaces, that is, a so-called rolled copper foil has been used. A technique has been developed that suppresses a decrease in charge / discharge efficiency of the battery using a foil (see Patent Document 1).

An electrolytic copper foil having a small difference in surface roughness between the front and back surfaces is produced by appropriately selecting a water-soluble polymer substance, a surfactant, an organic sulfur-based compound, chlorine ions, and the like and adding a trace amount. A typical known technique discloses a method for producing an electrolytic copper foil in which a compound having a mercapto group, a chloride ion, a low molecular weight glue having a molecular weight of 10,000 or less, and a high molecular weight polysaccharide are added to an electrolytic solution. (See Patent Document 2).
The electrolytic copper foil (current collector) produced by the production method is coated with graphite particles as an active material on the front and back, and further heated and pressed to form a copper foil with an active material layer, The negative electrode for a lithium ion secondary battery is used.

In recent years, lithium-ion secondary batteries using germanium, silicon, tin, etc., which are electrochemically alloyed with lithium during charging, have been proposed as technologies for achieving higher capacities of lithium-ion secondary batteries. (See Patent Document 3).

A negative electrode for a lithium ion secondary battery intended for high capacity is formed by depositing, for example, silicon as an amorphous silicon thin film or a microcrystalline silicon thin film on a base metal foil manufactured by a CVD method or a sputtering method. ing. Since the thin film layer of the active material prepared by such a method is in close contact with the current collector, it has been found that it exhibits good charge / discharge cycle characteristics (see Patent Document 4).

Recently, a forming method has been developed in which powdered silicon is slurried with an imide-based binder in an organic solvent, applied onto a copper foil, dried and pressed to form an electrode. However, such powdery silicon or tin is generally applied with a small particle size of 0.1 to 3 μm, with a uniform thickness and appropriate adhesion on the front and back of the metal foil as the negative electrode current collector. The coating yield is extremely poor.

Further, in such a negative electrode for a lithium ion secondary battery, for example, the volume of silicon active material expands by a maximum of about 4 times due to occlusion of lithium ions during charging, and shrinks by discharging lithium ions during discharging. To do. Due to the expansion and contraction of the volume of the active material layer accompanying charging and discharging, not only the active material peels from the current collector, but also a phenomenon in which stress acts on the current collector is a problem.

When an electrode made of a metal foil with an active material layer having a large expansion and contraction is housed in a battery and repeated charging and discharging a number of times, the current collector (metal foil) expands and contracts in the same manner, so that wrinkles are generated inside. In order to allow wrinkles, it is necessary to provide a design with a sufficient volume occupied by the electrodes in the battery, but on the other hand, the battery has a problem in that the energy density per unit volume (charge / discharge capacity) decreases. .
When trying to improve the energy density per unit volume (charge / discharge capacity), there is no room for the expansion and contraction of the current collector, so the current collector breaks without being able to withstand the internal stress and stable battery characteristics are achieved. There is a problem that it cannot be maintained.

Japanese Patent No. 3742144 Japanese Patent No. 3313277 JP-A-10-255768 Japanese Patent Laid-Open No. 2002-083594 Japanese Patent Publication No.53-39376

When a metal foil with an active material layer coated with an active material mainly composed of silicon, germanium, or tin is used as an electrode instead of graphite for an electrode for a lithium ion secondary battery, a charge / discharge reaction occurs. The volume of the active material layer expands and contracts, and a large stress acts on the current collector (metal foil), which may cause problems such as wrinkles on the current collector. Furthermore, when charging / discharging is repeated many times, there is a problem that the current collector rarely breaks. When physical deformation such as wrinkles occurs in the current collector, the volume occupied by the electrode in the battery slightly increases, and as a result, the energy density per volume decreases.
In addition, when a fracture crack occurs in the current collector, stable battery performance cannot be maintained for a long time, and charge / discharge characteristics (cycle characteristics) are deteriorated.

In addition, when coating active materials, silicon and tin have a small particle size, so when coated on the negative electrode current collector in the form of a slurry, the front and back have an appropriate adhesive strength with a uniform thickness. It is difficult to apply and the coating yield is extremely poor. In particular, when the difference in surface roughness between the front and back surfaces of the current collector is large, it becomes more difficult to apply the active material to the front and back surfaces with a uniform thickness. If the active material cannot be applied uniformly, the battery output characteristics and cycle characteristics will be adversely affected.

The present invention relates to a lithium ion secondary battery using a negative electrode in which an active material mainly composed of silicon, germanium, or tin is applied and deposited on a current collector. The main object of the present invention is to provide a lithium ion secondary battery that does not cause breakage of the electric current, has high adhesion between the active material and the current collector, and can maintain stable secondary battery characteristics for a long time. It aims at providing the metal foil as an electrical power collector for electrodes, especially an electrolytic copper foil.

At the same time, the present invention applies not only to the electrolytic copper foil but also to a metal foil employed as a current collector for a lithium ion secondary battery used for the same purpose as the electrolytic copper foil. For the current collector of the secondary battery electrode, which does not cause wrinkles and does not break the current collector, has high adhesion between the active material and the current collector, and can maintain stable secondary battery characteristics for a long time An object is to provide a metal foil.

The present invention relaxes the difference in conductivity at the adhesive interface between the metal foil for the current collector of the lithium ion secondary battery electrode and the active material, improves the conductivity of the active material layer, and increases the volume of the lithium ion secondary battery. One purpose is to increase the energy density per unit.

The present invention particularly relates to a current collector in a lithium ion secondary battery using an active material layer-attached metal foil, in which an active material mainly composed of silicon, germanium, or tin is applied and deposited on a current collector (metal foil). Lithium ion secondary that does not cause wrinkles in the body, does not cause breakage of the current collector, has high adhesion between the active material and the current collector (metal foil), and can maintain stable secondary battery characteristics for a long time It is another object to provide a battery, and to provide a metal foil with an active material layer as an electrode of the secondary battery.

The metal foil with a coating layer of the present invention is characterized in that a coating layer is provided on at least one surface of the untreated metal foil, and the coating layer contains free metal particles.

The coating layer is preferably a remeltable resin composition layer containing free metal particles.
The covering layer is preferably an active material layer containing free metal particles.

The coating layer is a remeltable resin composition layer containing free metal particles, and an active material layer is preferably provided on the resin composition layer.

In the metal foil with a coating layer of the present invention, a roughened layer is provided on at least one surface of the untreated metal foil, a coating layer is provided on the roughened layer, and the coating layer contains free metal particles. It is characterized by being.

The free metal particles contained in the coating layer are preferably metal particles released from the roughening treatment layer.

The coating layer provided on the roughening treatment layer is preferably a resin composition layer that can be remelted.
Moreover, it is preferable that the coating layer provided on the said roughening process layer is an active material layer.
Moreover, it is preferable that the coating layer provided on the roughening treatment layer is a layer in which an active material layer is provided on a remeltable resin composition layer.

The particle size of the free metal particles is preferably 0.05 μm to 3.5 μm.

The roughening treatment layer is preferably a roughening treatment layer containing at least one metal of copper, nickel, manganese, iron, chromium, tungsten, molybdenum, vanadium, and indium.

It is preferable to provide a film or release paper on at least the outermost layer surface of the metal foil with a coating layer.

The electrode for a secondary battery of the present invention is characterized in that an active material layer is provided on at least one surface of a metal foil, and the active material layer contains free metal particles.

In the secondary battery electrode of the present invention, a remeltable resin composition layer in which free metal particles are dispersed is provided on at least one surface of a metal foil, and an active material layer is provided on the resin composition. It is characterized by.

The electrode for a secondary battery of the present invention is provided with a roughening treatment layer on at least one surface of a metal foil, an active material layer is provided on the roughening treatment layer, and the active material layer contains free metal particles. Preferably it is.

The electrode for a secondary battery of the present invention is provided with a roughening treatment layer on at least one surface of a metal foil, a resin composition layer in which free metal particles are dispersed is provided on the roughening treatment layer, and the resin composition An active material layer is provided thereon.

The electrode for a secondary battery of the present invention is provided with a roughening treatment layer on at least one surface of a metal foil, and a remeltable resin composition layer in which free metal particles are dispersed on the roughening treatment layer, An active material layer is provided on the resin composition.

The roughening treatment layer is a roughening treatment layer formed by treatment in a plating bath containing at least one metal of copper, nickel, manganese, iron, chromium, tungsten, molybdenum, vanadium, and indium. Is preferred.

It is preferable that a film or a release paper is provided on at least the outermost surface of the secondary battery electrode.

The method for producing a metal foil with a coating layer according to the present invention is a method for producing a metal foil with a coating layer in which a coating layer containing free metal particles is provided on at least one side of an untreated metal foil, the cathode foil being electrolyzed on the surface of the metal foil. In plating, a current greater than the limiting current density is passed, a roughening treatment layer having a particle size of 0.1 μm to 3.5 μm is applied, a coating layer is formed on the roughening treatment layer, A part is mixed in the coating layer as free metal particles.

The coating layer is preferably a resin composition layer that can be remelted.
Moreover, it is preferable that the said coating layer is an active material layer.
Moreover, it is preferable that the said coating layer is a resin composition layer which can be remelted, and the active material layer is provided on this resin composition.

The method for producing a metal foil with a coating layer according to the present invention is a method for producing a metal foil with a coating layer in which a coating layer containing free metal particles is provided on at least one side of an untreated metal foil, and the surface of the metal foil is electrolytically plated. Then, a current exceeding the limit current density is passed, and a roughening treatment layer having a particle size of 0.1 μm to 3.5 μm is applied. On the roughening treatment layer, an active material, a binder, and, if necessary, a thickener, a slurry, The active material mixture is added and mixed to form an active material layer, and the metal foil on which the active material layer is formed is dried and added so that the metal-treated particles are incorporated into the active material layer as a conductive additive. And the roughened particles are contained as free metal particles in the active material layer.

The method for producing a metal foil with a coating layer of the present invention is a method for producing a metal foil with a coating layer in which a coating layer containing free metal particles is provided on at least one side of the metal foil, and the surface of the metal foil is electrolytically plated. A current is passed over the limit current density, a roughening treatment layer having a particle diameter of 0.1 μm to 3.5 μm is applied, a resin composition layer is formed on the roughening treatment layer, and the resin composition layer is formed on the resin composition layer. Then, an active material, a binder, and a thickener and slurry are added if necessary, and a mixed active material mixture is applied to form an active material layer, and the resin composition layer and the metal foil on which the active material layer is formed The roughening-treated particles are dried and pressurized so as to be incorporated into the resin composition layer as free metal particles. In the embodiment of the present invention, cathodic electroplating is used, but anodic electroplating has the same effect.

The resin composition layer formed on the roughening treatment layer is preferably a remeltable resin.

The electrode for a secondary battery according to the present invention is characterized in that the metal foil produced by the method for producing a metal foil with a coating layer is used as a current collector.

In the method for producing an electrode for a secondary battery according to the present invention, a roughened layer having a particle size of 0.1 μm to 3.5 μm is formed by electrolytic plating on the surface of an untreated metal foil to cause a current to flow beyond a limit current density. A surface roughening treatment step, an active material granulation step of adding and mixing an active material, a binder, and a thickener and a slurry if necessary, and the active material granulation step on one surface of the roughening treatment layer A first active material film forming step of applying the active material mixture granulated in step, a second active material film forming step of depositing the active material mixture on a film and laminating it on the other surface of the metal foil, The metal foil in which the active material layer is formed in the first and second steps is dried and pressurized so that the roughened particles are incorporated into the active material layer as a conductive additive, and the roughened particles are activated as free metal particles. It comprises a drying and pressurizing step to be contained in the material layer.

In the method for producing an electrode for a secondary battery according to the present invention, a roughened layer having a particle size of 0.1 μm to 3.5 μm is formed by applying an electric current exceeding the limit current density by electrolytic plating on the surface of the metal foil. Surface roughening treatment step (hereinafter referred to as burn plating), resin composition layer forming step for forming a resin composition layer on the roughening treatment layer, active material, binder, and thickener and slurry added if necessary An active material granulation step of mixing the active material, a first active material film forming step of applying the active material mixture granulated in the active material granulation step on one surface of the resin composition layer, The second active material film forming step of depositing the substance mixture on the film and laminating it on the other surface of the resin composition layer, and the roughening of the metal foil formed with the active material layer in the first and second steps The roughened particles are dried and pressurized so that the treated particles are taken into the active material layer as a conductive additive. Characterized by comprising the dry pressing step to be contained in the active material layer as a free metal particles.

The resin composition is preferably a resin composition that can be remelted.

The lithium ion secondary battery of the present invention is a secondary battery incorporating the electrode.

Since the metal foil having the coating layer of the present invention has a remeltable resin composition layer in which free metal particles are mixed as a coating layer on the surface of the metal foil, for example, an active material layer provided on the surface of the coating layer Adhesiveness is improved, and excellent effects such as relaxation of electrolysis between the metal foil and the active material layer are obtained.

According to the metal foil for a current collector of a lithium ion secondary battery electrode of the present invention, when the foil is used as a current collector, the metal constituting the roughening treatment layer is mixed into the active material layer, so that it is conductive. Improves the energy density per volume of the lithium ion secondary battery.
In addition, when the metal foil of the present invention is used as a current collector, the generation of wrinkles and the like can be suppressed against the expansion and contraction of the active material that occurs during charging and discharging, and the energy density per volume of the lithium ion secondary battery Can be increased. Further, to provide a metal foil for a current collector of a lithium ion secondary battery electrode having stable output performance for a long time because the current collector is not stress-ruptured and the adhesiveness between the active material and the current collector is high. Can do.

Since the lithium ion secondary battery of the present invention uses a metal foil for the negative electrode of the battery, wrinkles and the like are not generated in the current collector due to charge and discharge, and the energy density per volume of the lithium ion secondary battery is increased. In addition, since the current collector is not stress-ruptured and the adhesiveness between the active material and the current collector is high, a lithium ion secondary battery with stable output performance for a long time can be provided.

It is a manufacturing process flowchart which shows 1st embodiment which manufactures metal foil with a coating layer. It is a schematic diagram which shows the cross section of the metal foil with a coating layer of 1st embodiment. It is a manufacturing process flowchart which shows 2nd embodiment which manufactures metal foil with a coating layer. It is a schematic diagram which shows the cross section of the metal foil with a coating layer of 2nd embodiment. It is a manufacturing process flowchart which shows 3rd embodiment which manufactures metal foil with a coating layer. It is a schematic diagram which shows the cross section of the metal foil with a coating layer of 3rd embodiment. It is a manufacturing process flowchart which shows 4th embodiment which manufactures metal foil with a coating layer. It is explanatory drawing which shows the manufacturing apparatus of 4th embodiment of metal foil with a coating layer. It is a manufacturing process flowchart which shows 5th embodiment which manufactures metal foil with a coating layer. It is a manufacturing apparatus of 5th embodiment of metal foil with a coating layer. It is a manufacturing apparatus of 6th embodiment of metal foil with a coating layer. It is explanatory drawing which shows the manufacture flowchart of 6th embodiment of metal foil with a coating layer. It is a manufacturing process flowchart which shows 7th embodiment which manufactures metal foil with a coating layer. It is explanatory drawing which shows the manufacturing apparatus of 7th embodiment of metal foil with a coating layer. It is a manufacturing process flowchart which shows 8th embodiment which manufactures metal foil with a coating layer. It is explanatory drawing which shows the manufacturing apparatus of 8th embodiment of metal foil with a coating layer.

1st embodiment It demonstrates with reference to the flowchart shown in FIG. 1 about 1st embodiment which manufactures the metal foil with a coating layer of this invention.
Step 1 (Preparation of free metal particles)
Metal particles made of copper, nickel, manganese, iron, chromium, tungsten, molybdenum, vanadium, and indium are prepared. The particle size of the metal particles is preferably in the range of 0.1 μm to 3.5 μm. One type or a combination of two or more types of metal particles is selected depending on the conductivity of the resin composition to be mixed.

Step 2 (Preparation of remeltable resin composition)
A remeltable resin composition is prepared. As the remeltable resin composition, commercially available thermoplastic resin compositions [for example, vinylidene fluoride resin (hereinafter PVDF)] and thermosetting resin compositions (for example, thermosetting polyimide resin) can be used.
In addition, as this embodiment, it is preferable to select the resin composition which can be adhere | attached with the following active material layer provided on a resin composition layer.

Step 3 (Preparation of conductive resin composition)
The free metal particles selected in Step 1 are mixed into the remeltable resin composition selected in Step 2 to create a resin composition imparted with conductivity.

Step 4 (Coating)
In step 3, the resin composition containing metal particles is coated on the surface of a metal foil (copper foil, aluminum foil, etc.). The coating can be performed by a general method such as a press method.
Specifically, a thermosetting polyimide resin is employed as the thermosetting resin composition, dissolved in a solvent with free metal particles added to the resin, and applied to the surface of the metal foil, and then the thermosetting polyimide resin. The solvent is evaporated so as to become a B-stage resin and dried to form a remeltable resin layer containing free metal particles (B-stage resin) on the surface of the metal foil.
Alternatively, a resin composition containing free metal particles is shaped into a plate shape and pasted on the surface of the metal foil with a press or the like to form a metal foil with a coating layer.
The metal foil which has the remeltable resin composition layer (coating layer) containing a free metal particle by the above process can be manufactured.
FIG. 2 is a schematic view of the metal foil 10 with a coating layer in which the resin composition layers 11 and 12 that can be remelted are provided on both surfaces of the metal foil 10. As shown in the figure, free metal particles are dispersed in the coating layers 11 and 12.
In FIG. 2, the composition layers 11 and 12 are provided on both surfaces of the metal foil 10, but if only one surface is satisfactory, it is not necessary to provide the composition layers on both surfaces.

Second Embodiment A second embodiment for producing a metal foil with a coating layer of the present invention will be described with reference to a flowchart shown in FIG.

Step 21 (Preparation of free metal particles)
Metal particles made of copper, nickel, manganese, iron, chromium, tungsten, molybdenum, vanadium, and indium are prepared. The particle size of the metal particles is preferably in the range of 0.1 μm to 3.5 μm. One type or two or more types of metal particles are selected depending on the conductivity of the active material layer to be mixed.

Step 22 (active material mixture creation process)
An active material mixture is prepared by mixing an active material, a binder, and, if necessary, conductive carbon black or a thickener and a slurry. In forming the active material layer, for example, polyimide is mixed as a binder.

Step 23 (formulation)
The free metal particles of Step 1 are mixed into the active material mixture prepared in Step 2 to impart conductivity to the active material layer.

Step 24 (coating)
The active material mixture blended in step 3 is applied to one side of a metal foil (copper foil, aluminum foil, etc.) 30 and coated. The coating can be performed by a general method such as a press method.
FIG. 4 is a schematic view of a metal foil with a coating layer in which an active material layer 32 is provided on one side of the metal foil 30. As shown in the figure, free metal particles 34 are dispersed in a gap between the active materials 33 in the coating layer (active material layer) 32.

In FIG. 4, the active material layer 32 is provided on one surface of the metal foil 30, but when it is necessary to provide the active material layer 32 on both surfaces, an active material layer is provided on both surfaces of the foil in the following steps.

Step 25 (coating)
The active material mixture of step 3 is applied and coated on the other surface of the metal foil (copper foil, aluminum foil, etc.). The coating can be performed by a general method such as a press method.
The metal foil which gave the active material layer (coating layer) containing a free metal particle on the single side | surface or both surfaces by the above process can be manufactured.

Third Embodiment A third embodiment for producing a metal foil with a coating layer of the present invention will be described with reference to a flowchart shown in FIG.

Step 31 (Preparation of free metal particles)
Metal particles made of copper, nickel, manganese, iron, chromium, tungsten, molybdenum, vanadium, and indium are prepared. The particle size of the metal particles is preferably in the range of 0.1 μm to 3.5 μm. One type or a combination of two or more types of metal particles is selected depending on the conductivity of the resin composition to be mixed.

Step 32 (Preparation of remeltable resin composition)
A remeltable resin composition is prepared. As a remeltable resin composition, a commercially available thermoplastic resin composition [for example, vinylidene fluoride resin (hereinafter referred to as PVDF)], a thermosetting resin composition (for example, a thermosetting polyimide resin) is used. it can.
In addition, as this embodiment, it is preferable to select the resin composition which can be adhere | attached with the following active material layer provided on a resin composition layer.

Step 33 (formulation)
The metal composition selected in step 31 is mixed into the meltable resin composition selected in step 32 to create a resin composition imparted with conductivity.

Step 34 (coating)
In step 3, the resin composition containing metal particles is coated on the surface of a metal foil (copper foil, aluminum foil, etc.). The coating can be performed by a general method such as a press method.
Specifically, a thermosetting polyimide resin is employed as the thermosetting resin composition, dissolved in a solvent with free metal particles added to the resin, and applied to the surface of the metal foil, and then the thermosetting polyimide resin. The solvent is evaporated so as to become a B-stage resin and dried to form a remeltable resin layer containing metal particles (B-stage resin) on the surface of the metal foil.

Step 35 (active material mixture creation process)
An active material mixture is prepared by mixing an active material, a binder, and, if necessary, conductive carbon black or a thickener and a slurry. In forming the active material layer, for example, polyimide is mixed as a binder.

Step 36 (formation of active material layer)
An active material layer is formed with the active material mixture blended in step 35 on the resin composition layer (coating layer) formed in step 34.
FIG. 6 is a schematic view of a metal foil with a coating layer in which a resin composition layer is provided on one surface of a metal foil 30 and an active material layer 32 is provided on the surface of the composition layer. As shown in the figure, free metal particles 33 are dispersed in the composition layer, and a part of the free metal particles enters the active material layer 32 thereon.
In the figure, reference numeral 37 denotes a binder.
In FIG. 4, the composition layer and the active material layer 32 are provided on one surface of the metal foil 30. However, when it is necessary to provide both surfaces, the composition layer and the active material layer are provided on both surfaces.

Step 37 (Create electrode)
The metal foil with an active material layer prepared in step 35 is formed for an electrode.
Step 38 (Battery creation)
The electrode created in step 36 is incorporated into the positive electrode or the negative electrode to complete the battery.

Fourth Embodiment A fourth embodiment for producing a metal foil with a coating layer according to the present invention will be described with reference to a flowchart shown in FIG. 7 and a production apparatus shown in FIG.

Step 41 (surface roughening process)
As shown in FIG. 8, the metal foil 1 is guided to the surface roughening treatment tank 2, and metal particles are grown on the surface of the metal foil 1 by plating to form the roughened metal layer 3.
As shown in FIG. 8, the metal foil 1 is guided to the roughening treatment tank 2 through the feeding electrode 20 and passes between the plating

electrodes

22, 24, and 26 arranged in the roughening treatment tank 2. Led. In FIG. 8, the plating

electrodes

22, 24, and 26 are arranged at three locations to roughen both surfaces of the metal foil 1. However, when the roughening treatment is performed only on one side of the foil, for example, the electrode 26 is omitted. can do. The roughening process conditions will be described later.
Next, the roughened metal layer 3 is guided to the water washing tank 4 and washed with water.
The metal foil washed with water is guided to the antirust treatment tank 5 and a rust preventive agent is applied to the surface of the roughened metal layer 3. In addition, when there is no possibility that a roughening metal layer will oxidize, a rust prevention process can be abbreviate | omitted.

Step 42 (Formation of remeltable resin composition layer)
The resin composition is coated on the surface of the metal foil (copper foil, aluminum foil, etc.) on which the roughened layer is formed in step 2. The coating method can be performed by a general method such as a press method. Here, as shown in FIG. 8, the resin composition is melted in a solvent and roughened in step 41. The method of applying to will be described.

As shown in FIG. 8, the resin composition is dissolved in a solvent and filled in the container 6. The metal foil provided with the rust prevention layer is guided to the container 6 (filled with a resin composition dissolved in a solvent), and a solution made of the resin composition is applied to the surface.

Step 43 (drying process)
After applying the resin composition to the surface of the metal foil, the solvent is evaporated and dried by the solvent evaporation device 8.

Step 44 (winding process)
The dried metal foil with a resin composition layer is wound on a winder 11. In this manufacturing process or in a subsequent process, some of the roughened particles enter the resin composition, and a remeltable resin layer containing metal particles on the surface of the metal foil as shown in FIG. Resin) can be formed.

With reference to FIG. 8, it demonstrates still in detail about the formation process of the remeltable resin composition layer of step 42. FIG. The roughening treatment layer formed by the plating method is preferably applied by roughening treatment by burnt plating. In this state, the roughened layer applied by burnt plating maintains an unhealthy state in which the roughened particles fall off (powder off). In this state, a metal foil is immersed and passed through a tank 6 of a solution in which, for example, vinylidene fluoride resin (hereinafter referred to as PVDF) is dissolved in a 1-methyl-2-pyrrolidone (NMD) solvent on the roughened surface. The weight ratio of PVDF controls the amount of adhesion by appropriately adjusting the solvent concentration. Then, the resin adhered to the surface of the metal foil is dried over a predetermined time required to evaporate the solvent, and the roughened particles do not fall off, and become a roughened copper foil with a resin composition. .
When a thermosetting polyimide resin is used as the remeltable resin composition, the polyimide is dissolved in an appropriate solvent by adjusting the weight ratio, and the solution vessel 6 is roughened by the burnt plating as described above. The treated copper foil is immersed and passed through. Thereafter, the solvent is evaporated over a predetermined period of time so that the thermosetting polyimide resin becomes a B-stage resin, dried, and attached to the surface of the metal foil. Thus, the metal foil with a coating layer in which the roughened particles are mixed into the B-stage resin can be produced.
In the present invention, the resin composition layer is applied and dried on the dendritic rough particle layer adhering in such a brittle state. Dendritic roughened particles are destroyed during application of the resin composition, during expansion / contraction during drying, or in subsequent steps, and the broken particles are dispersed in the resin composition layer as shown in FIG. It is taken in in the resin composition layer.

Fifth Embodiment A fifth embodiment for manufacturing a metal foil with a coating layer according to the present invention will be described with reference to a flowchart shown in FIG. 9 and a manufacturing apparatus shown in FIG.

Step 51 (surface roughening process)
As shown in FIG. 9, the metal foil 1 is guided to the surface roughening treatment tank 2, and metal particles are grown on the surface of the metal foil I by plating to form the roughened metal layer 3.
As shown in FIG. 10, the metal foil 1 is guided to the roughening treatment tank 2 through the feeding electrode 20 and passes between the plating

electrodes

22, 24, and 26 arranged in the roughening treatment tank 2. Led. In FIG. 10, plating

electrodes

22, 24, and 26 are arranged at three locations for roughening both surfaces of the metal foil 1. However, when roughening is performed only on one surface of the foil, for example, the electrode 26 is omitted. can do. The roughening process conditions will be described later.
Next, the roughened metal layer 3 is guided to the water washing tank 4 and washed with water.
The metal foil washed with water is guided to the antirust treatment tank 5 and a rust preventive agent is applied to the surface of the roughened metal layer 3. In addition, when there is no possibility that a roughening metal layer will oxidize, a rust prevention process can be abbreviate | omitted.

Step 52 (active material mixture creation process)
An active material, a binder, and, if necessary, conductive carbon black or a thickener and a slurry are mixed to prepare an active material mixture 8, and the active material mixture 8 is supplied to the hoppers 6 and 7.
In forming the active material layer, it is preferable to use, for example, polyimide as a binder to form a homogeneous slurry coating film.

Step 53 (first active material layer forming step)
If necessary, the surface of the metal foil subjected to the surface roughening treatment is rust-prevented with the rust-preventing treatment layer 5, and the active material mixture 8 is poured uniformly from the hopper 6 onto one surface thereof. 8 is dried to form an active material layer 31.

Step 54 (second active material layer forming step)
Next, the active material mixture 8 is poured uniformly from the hopper 7 onto the other surface and dried by the drying device 10 to form the active material layer 32.

Step 55 (drying / pressurizing process)
A metal foil with an active material layer having active material layers 31 and 32 formed on both sides is passed through a press 11 and heated and pressurized. In this heating / pressurizing step, the active material layers 31 and 32 are uniformly adhered to the surface of the metal foil, and are moved by being pressed against the roughened particles in the pressing step, as shown in FIG. Roughened metal particles 35 that are not fixed to the foil I are separated from the base metal foil 1 and taken into and dispersed in the active material layer 31 (32), so that the interface between the active material layer 31 (32) and the base metal foil 1 is dispersed. Improve conductivity. In the figure, 33 is an active material, 37 is a binder and a conductive material to be added if necessary. The distribution of the roughened metal particles is characterized by being concentrated on the base metal foil side and decreasing toward the outermost surface of the active material layer.

Step 56 (winding process)
The pressed and dried metal foil with the active material layer is taken up by the winder 12 and conveyed to the manufacturing process of the electrode (step 47) and battery (step 48) as the next process.

Sixth Embodiment A sixth embodiment for manufacturing a metal foil with a coating layer according to the present invention will be described with reference to a flowchart shown in FIG. 11 and a manufacturing process diagram shown in FIG.

Step 61 (surface roughening process)
As shown in FIG. 12, the metal foil 1 is guided to the surface roughening treatment tank 2, and metal particles are grown on the surface of the metal foil I by plating to form the roughened metal layer 3.
As shown in FIG. 12, the metal foil 1 is guided to the roughening treatment tank 2 through the feeding electrode 20 and passes between the plating

electrodes

22, 24, and 26 arranged in the roughening treatment tank 2. Led. In FIG. 12, plating

electrodes

22, 24, and 26 are disposed at three locations for roughening both surfaces of the metal foil 1. However, when roughening is performed only on one surface of the foil, for example, the electrode 26 is omitted. can do. The roughening process conditions will be described later.
Next, the roughened metal layer 3 is guided to the water washing tank 4 and washed with water.
The metal foil washed with water is guided to the antirust treatment tank 5 and a rust preventive agent is applied to the surface of the roughened metal layer 3. In addition, when there is no possibility that a roughening metal layer will oxidize, a rust prevention process can be abbreviate | omitted.

Step 62 (active material mixture creation process)
An active material, a binder, and, if necessary, conductive carbon black or a thickener and a slurry are mixed to prepare an active material mixture 8, and the active material mixture 8 is supplied to the hoppers 6 and 7.
In forming the active material layer, it is preferable to use, for example, polyimide as a binder to form a homogeneous slurry coating film.

Step 63 (first active material layer forming step)
If necessary, the surface of the metal foil subjected to the surface roughening treatment is subjected to a rust prevention treatment with the rust prevention treatment layer 5, and the active material mixture 8 is poured uniformly from one surface of the hopper 6 to form an active material layer 31. The surface of the active material layer 31 is supplied with a plastic film or release paper 13 from the film supply roll 15 (when it is not necessary to distinguish between the plastic film and the release paper, both are simply expressed as the film 13) and attached.

Step 64 (second active material layer forming step)
The active material mixture 8 is uniformly poured from the hopper 7 into the film 13 supplied from the supply roll 14 of the film 13, and the active material mixture 8 conveyed from the film 13 is applied to the other surface of the surface-roughened metal foil. Then, the active material layer 32 is formed.

Step 65 (drying / pressurizing process)
The metal foil with an active material layer having active material layers 31 and 32 formed on both sides is heated and pressurized through a dryer 9 and a press 11. In this heating / pressing step, the active material layers 31 and 32 are uniformly adhered to the surface of the metal foil, and some of the metal particles of the roughened metal layer 3 grown by the surface treatment in this pressing step are active material. Incorporated into the layer. In addition, since the process in which a free metal particle is taken in in an active material layer was demonstrated in the said 5th embodiment, it abbreviate | omits here.

Step 66 (winding process)
The pressed and dried metal foil with an active material layer is taken up by the winder 12 and conveyed to the electrode / battery manufacturing process, which is the next process.
In the present embodiment, the film 13 is provided on the active material layer 32. Therefore, the active material layer 32 and the active material layer 32 are not in direct contact with each other when wound on the winder (for example, bobbin) 12, and the active material layer is not damaged by winding.
Moreover, the trouble at the time of battery assembly can be reduced by using the same thing as the separator used for the electrode of a lithium ion secondary battery, for example. In addition, when it is not necessary to cover the active material layer surface with a film, it can be deleted after the active material layer drying step.

Seventh Embodiment A seventh embodiment for manufacturing a metal foil with a coating layer according to the present invention will be described with reference to a flowchart shown in FIG. 13 and a manufacturing apparatus shown in FIG.

Step 71 (surface roughening process)
As shown in FIG. 13, the metal foil 1 is guided to the surface roughening treatment tank 2, and metal particles are grown on the surface of the metal foil I by plating to form the roughened metal layer 3.
As shown in FIG. 14, the metal foil 1 is guided to the roughening treatment tank 2 through the feeding electrode 20 and passes between the plating

electrodes

22, 24, 26 arranged in the roughening treatment tank 2. Led. In FIG. 14, plating

electrodes

Step 72 (first remeltable resin composition layer forming step)
A remeltable resin composition is supplied to one side of the roughened metal foil. As the remeltable resin composition, a commercially available thermoplastic resin composition can be used. In the present embodiment, as described above, it is preferable to select a resin composition that can adhere to the active material layer provided on the resin composition layer.
As shown in FIG. 13, a film 40 of a remeltable resin composition is supplied to one side of the metal foil 1, and both are attached by a pressure roll 41. If necessary, thermocompression bonding.

Step 73 (active material mixture creation process)
The active material, binder, conductive carbon black or thickener and slurry are mixed as necessary, and the active material mixture 8 is supplied to the hoppers 6 and 7.
In forming the active material layer, the active material 31 and the metal foil 1 are in close contact with the remeltable resin composition layer 40. If necessary, for example, polyimide is used as a binder to form a homogeneous slurry coating film. Is preferred.

Step 74 (first active material layer forming step)
The active material mixture 8 is uniformly poured from the hopper 6 into the metal foil whose one surface is coated with the remeltable resin composition 40, and the active material mixture 8 is dried by the drying device 9 to form the active material layer 31. .
Step 75 (second remeltable resin composition layer forming step)
As in step 72, as shown in FIG. 13, a remeltable resin composition film 42 is supplied to the other surface of the metal foil 1, and the both are pasted by the pressure roll 41. If necessary, thermocompression bonding.
Step 76 (second active material layer forming step)
Next, the active material mixture 8 is uniformly poured from the hopper 7 onto the surface of the remeltable resin composition film 42, and is dried by the drying device 10 to form the active material layer 32.

Step 77 (drying / pressurizing process)
A metal foil with an active material layer having active material layers 31 and 32 formed on both sides is passed through a press 11 and heated and pressurized. In this heating / pressurizing step, the active material layers 31 and 32 are uniformly adhered to the surface of the metal foil via the remeltable resin composition layers 40 and 42. In addition, a part of the metal particles of the roughened metal layer 3 grown by the surface treatment is taken into the resin composition layer that can be remelted in the attaching step and the heating / pressurizing step.
As shown in the schematic diagram of FIG. 6, the roughened metal particles 35 move away from the surface of the metal foil in a remeltable resin composition layer sticking step and an active material layer pressurizing step, and can be remelted. It is taken in and dispersed in the resin composition layer 40 (42), and the conductivity at the interface between the active material layer 31 (32) and the metal foil 1 is improved. In the figure, 33 is an active material, 37 is a binder and a conductive material to be added if necessary. The distribution of the roughened metal particles is characterized by being concentrated on the metal foil side and decreasing toward the active material layer side.

Step 78 (winding process)
The pressed and dried metal foil with an active material layer is taken up by the winder 12 and conveyed to the electrode / battery manufacturing process, which is the next process.
In addition, by using the same film as the separator used for the electrode of the lithium ion secondary battery, for example, the labor at the time of battery assembly can be reduced.

Eighth Embodiment An eighth embodiment for manufacturing a metal foil with a coating layer according to the present invention will be described with reference to a flowchart shown in FIG. 15 and a manufacturing process diagram shown in FIG.

Step 81 (surface roughening process)
As shown in FIG. 16, the metal foil 1 is guided to the surface roughening treatment tank 2, and metal particles are grown on the surface of the metal foil I by plating to form the roughened metal layer 3.
As shown in FIG. 15, the metal foil 1 is guided to the roughening treatment tank 2 through the feeding electrode 20 and passes between the plating

electrodes

22, 24, 26 arranged in the roughening treatment tank 2. Led. In FIG. 13, plating

electrodes

Step 82 (Remeltable resin composition layer forming step)
A remeltable resin composition layer 40 is supplied to both surfaces of the roughened metal foil 1. As the remeltable resin composition, a commercially available thermoplastic resin composition can be used. In addition, as this embodiment, it is preferable to select the resin composition which can adhere | attach with the active material layer provided on a resin composition layer.
As shown in FIG. 16, a remeltable resin composition film 40 is supplied to both surfaces of the metal foil 1, and both are pasted with a pressure-bonding roll 41. If necessary, thermocompression bonding.
In addition, by using the same separator as the separator used for the electrode of the lithium ion secondary battery, for example, the labor at the time of battery assembly can be reduced.

Step 83 (active material mixture creation process)
The active material, binder, conductive carbon black or thickener and slurry are mixed as necessary, and the active material mixture 8 is supplied to the hoppers 6 and 7.
In forming the active material layer, the active material 31 and the metal foil 1 are in close contact with the remeltable resin composition layer 40. If necessary, for example, polyimide is used as a binder to form a homogeneous slurry coating film. Is preferred.

Step 84 (first active material layer forming step)
The active material mixture 8 is poured uniformly from the hopper 6 onto one surface of the metal foil on which the remeltable resin composition layer is formed, the active material layer 31 is formed, and a film is supplied to the surface of the active material layer 31 The film 13 is supplied from the roll 15 and attached.

Step 85 (second active material layer forming step)
The active material mixture 8 is uniformly poured from the hopper 7 into the film 13 supplied from the supply roll 14 of the film 13, and the active material mixture 8 conveyed from the film 13 is coated with a remeltable resin composition layer The active material layer 32 is formed by supplying the other surface of the foil.

Step 86 (drying / pressurizing process)
A metal foil with an active material layer having active material layers 31 and 32 formed on both sides is passed through a press 11 and heated and pressurized. In this heating / pressurizing step, the active material layers 31 and 32 are uniformly adhered to the surface of the metal foil via the remeltable resin composition layers 40 and 42. In addition, a part of the metal particles of the roughened metal layer 3 grown by the surface treatment is taken into the resin composition layer that can be remelted in the attaching step and the heating / pressurizing step.

Step 87 (winding process)
The pressed and dried metal foil with an active material layer is taken up by the winder 12 and conveyed to the electrode / battery manufacturing process, which is the next process.
In the present embodiment, the film 13 is provided on the active material layer 32. Therefore, the active material layer 32 and the active material layer 32 are not in direct contact with each other when wound on the winder (for example, bobbin) 12, and the active material layer is not damaged by winding.
Moreover, the trouble at the time of battery assembly can be reduced by using the same thing as the separator used for the electrode of a lithium ion secondary battery. In addition, when it is not necessary to cover the active material layer surface with a film, it can be deleted after the active material layer drying step.

Step 88
The metal foil having the prepared active material layer is finished into a battery electrode.
Step 89
The battery is completed by incorporating the above electrode into the battery.

Among the metal foils with a coating layer of the present invention, the metal foil provided with the active material layer as the coating layer can be directly used as a battery electrode because the active material layer is formed on the surface of the metal foil. Therefore, a metal suitable for the current collector constituting the battery electrode is selected as the metal foil. For example, an aluminum foil is selected as the positive electrode of the lithium ion secondary battery, and a copper foil is selected as the negative electrode.
In the following description, an electrolytic copper foil may be selected and described as the metal foil, but the electrolytic copper foil can be replaced with a rolled copper foil.
Moreover, not only for the electrolytic copper foil, but also for the metal foil employed as a current collector for a lithium ion secondary battery used for the same purpose as the electrolytic copper foil, or other batteries, like the copper foil, Lithium ion secondary that does not cause wrinkles in the current collector, does not cause breakage of the current collector, has high adhesion between the active material and the current collector metal foil, and can maintain stable secondary battery characteristics for a long time Of course, any metal foil that can be selected as a battery electrode (metal foil with an active material layer) can be used as a metal foil with an active material layer.

In this embodiment, the roughening process layer is provided by the burnt plating method which sends the electric current more than the limiting current density in an electrolytic bath on the surface of metal foil, for example, copper foil, in the surface roughening process. The roughening layer formed by the roughening process by the burnt plating method is formed in a dendritic shape, and the tip of the dendritic roughening layer is formed brittle.
In this embodiment, a roughened layer is formed on the surface of the base metal foil having a surface roughness Rz of 0.5 to 5 μm by a burnt plating method. In the roughening treatment, the particle size is preferably grown to 0.1 μm to 3 μm. Moreover, when providing an active material layer on both surfaces of a base metal, it is preferable that the difference in roughness Rz between the front and back surfaces of the base metal foil is 2.5 μm or less.

In the step of growing in the form of particles and providing the tip portion of the roughened layer with the strength to drop and disperse in the active material layer in the step of providing the active material layer on the surface of the roughened layer, the cathode electrolytic plating It is preferable to apply by the burn plating method.
However, the plating method is not limited to the burn plating method as long as the metal particles grown by the surface treatment can be grown in the above preferred range. The surface of the metal foil is subjected to a surface roughening treatment, and the grown tip portion of the particle roughening treatment layer is a step of providing an active material layer on the surface of the roughening treatment layer. Of course, any method can be adopted as long as it is a plating method provided with the strength of dropping and dispersing.

Also, when roughening is performed on the front and back surfaces of the metal foil by the burnt plating method, a metal foil having a smooth surface is selected, and a current is passed beyond the limit current density in the electrolytic bath, so that the particle size is 0.1 μm to 3 μm. A dendritic roughening treatment layer of .5 μm is formed so that the surface roughness Rz of the roughening treatment layer is 0.5 to 5 μm and the difference in surface roughness Rz between the front and back surfaces is 2.5 μm or less. Is preferred.

When providing the active material layers on both the front and back surfaces, if the metal foil is an electrolytic copper foil, the crystal structure of the cross section is preferably composed of fine granular crystals. This is because when the crystal structure of the copper foil is a granular crystal, the difference in roughness between the front and back surfaces can be reduced, and the difference in the roughness Rz value after applying the roughened particles can be further reduced. If the copper foil has a columnar crystal structure, the difference between the front and back roughness becomes large, and it becomes difficult to eliminate the difference even after the roughening treatment.

The metal foil for a lithium ion secondary battery electrode of the present invention has a particle size of 0 by burnt plating (hereinafter sometimes simply referred to as burnt plating) in which a current equal to or higher than the limiting current density in the electrolytic bath is applied to the front and back surfaces of the base metal foil. A layer of roughened particles of 1 μm to 3 μm is provided, the surface roughness Rz of each surface is 0.5 to 5 μm, and the difference between the front and back surface roughness Rz is 2.5 μm or less.
When the metal foil is, for example, an electrolytic copper foil, the roughening particles are applied to the surface of the base copper foil, thereby improving and improving the adhesion with the active material and changing the volume accompanying expansion and contraction inside the battery. Stress relaxation can be absorbed by the void space obtained by roughening.

When the metal foil is an electrolytic copper foil, the material for forming the roughened layer is Cu roughened particles, or particles containing Cu, the main component of which is Fe, Ni, Cr, W, Mo, V, or a plurality thereof. It is preferable that By forming a roughened layer with roughened particles comprising Cu or a copper alloy composition containing Cu as a main component, the adhesion between the roughened particles and the base copper foil is improved, and the particle size of the roughened particles is reduced. By appropriately controlling the current density (limit current density) of the burnt plating, it becomes easy to arbitrarily adjust the surface roughness Rz value.

The copper foil as the metal foil may be an electrolytic copper foil or a rolled copper foil, the surface roughness is about 0.8 to 2.0 μm, and the grain boundary structure at room temperature is from a granular crystal having a particle size of 5 μm or less. In terms of physical properties, it is preferable that the tensile strength (TS) is 300 MPa or more at room temperature, the elongation (E) is 3.5% or more, and in addition, the copper capable of maintaining the tensile strength after 150 ° C. × 15 hours is 250 MPa or more. A foil is particularly preferred.

Generally, as the crystal grain size increases, the tensile strength (T.S) of the metal foil decreases and the elongation (E) tends to increase. When germanium, silicon, tin, etc. are used for the negative electrode active material, if the strength (TS) of the current collector (metal foil) is low, the battery will expand and contract regardless of the roughening treatment. The metal foil cannot be absorbed and cracks occur in the metal foil. In order to avoid this, it is preferable that the tensile strength is 300 MPa or more and the elongation is 3.5% or more. In this case, the crystal structure grain size is preferably 5 μm or less.

Also, it is well known that there is a drying step during the manufacturing process of the negative electrode current collector for a lithium ion secondary battery, and that the characteristics of the battery deteriorate if this drying is insufficient. The drying conditions at this time are generally about 100 to 200 ° C. and about 5 to 20 hours. If the current collector (metal foil) is plastically deformed or softened at this time, the foil breaks and breaks during charging and discharging for the reasons described above, so the strength (hardness) of the foil after the drying process Is also an important component of physical properties.

It is copper foil that has the most mechanical property fluctuation under the drying process conditions using metal foil.
As a technology to suppress recrystallization (plastic deformation) during heating of the electrolytic copper foil, the additive composition concentration in the electrolytic solution during the electrolytic foil production is changed to MPS (3-mercapto 1- A foil production method is recommended in which 3 to 10 ppm of sodium propanesulfonate), 15 to 20 ppm of HEC (hydroxyethyl cellulose / polymer polysaccharide), and 30 to 70 ppm of animal glue are set.

The surface area ratio after the roughening particle application treatment is preferably 2.5 to 5 times. The surface area ratio is measured by using KEYENCE VK-8500 to measure the area of 2500μm ² (50μm × 50μm) on the surface of the metal foil. Based on this value, the base metal foil (before roughening) and the area after roughening Is expressed as a ratio. That is, when the surface area ratio is 1, it means that the surface area does not change before and after the roughening treatment. When the area after the roughening treatment is 5000 μm ² , the surface area ratio is doubled.

The tensile strength (TS) and elongation (E) of the present invention are values measured by a method defined in Japanese Industrial Standard (JISK6251).
The surface roughness Rz is a ten-point average roughness and an arithmetic surface roughness defined in Japanese Industrial Standards (JIS B0601-1994), and is a value measured with a general-purpose surface roughness meter.

In the case where the front and back surfaces of the metal foil are roughened by the burn plating method, the surface roughness Rz of the front and back surfaces of the base metal foil is preferably a smooth surface of 0.5 to 5 μm.
The burnt plating method is a plating method in which a current equal to or higher than the limiting current density in the electrolytic bath is passed, and is suitable as a roughening treatment method for imparting uniform unevenness to the surface of a smooth base metal foil. The front and back surfaces of the metal foil are roughened by this burnt plating method.

As a method for roughening the surface of a metal foil, particularly an electrolytic copper foil by burn plating, for example, a method used for a copper foil for printed circuit disclosed in Patent Document 5 (Japanese Patent Publication No. 53-39376) is used. General and preferably used.
However, in Patent Document 5, after forming a grainy copper plating layer by “yake plating”, “capsule plating” is performed on the grainy copper plating layer so as not to impair the uneven shape, This is a technique for forming a smooth, rough copper-like copper layer that does not drop off (does not fall off) granular copper by forming a smooth plating layer.

The present invention does not implement the capsule plating technique pointed out in Patent Document 5, and is in a state of roughening treatment by burnt plating, that is, an unhealthy state in which the roughened particles fall off (powder off). It is characterized by holding.

In the present invention, the reason why the process is stopped only by the burn plating is as follows.
When burnt plating is applied to the surface of the base metal foil, dendritic roughened particles uniformly adhere to the front and back surfaces of the foil. The roughening particles extending in a dendritic shape are attached to the front and back surfaces of the foil in a brittle state where the tip is easily broken and dropped off.
In this invention, an active material is apply | coated on the dendritic roughening particle layer adhering in such a brittle state. When an active material composition having an active material and a binder is applied to the remeltable roughened copper foil with resin, and dried and pressed, the attached resin becomes liquid again and dendritic roughening The particles are broken during application of the active material, during expansion / contraction during drying, or during pressing, and the broken particles are dispersed in the active material composition and taken in as part of the active material composition.

In addition, the burnt plating layer does not become an obstacle in the process of creating the active material layer.
After the active material composition is applied, dried, and subjected to a heat and pressure press process, an unnecessary solvent that has formed the active material in a slurry state is volatilized and the active material is solidified. At that time, the dendritic particles fall off, but the dropped coarse particles are taken into the active material layer, and the portion where the dendritic active material does not fall off constitutes the roughening (unevenness) of the copper foil surface. On the surface, the active material layer is firmly bonded to the front and back of the copper foil with a binder. Accordingly, in the roughening treatment by burn plating, the active material layer is formed in a state where the tip portion extended in a dendritic state enters the active material layer and the copper particles are liberated in the active material. The base part is formed with a roughened shape on the surface of the copper foil along the shape of the active material, not only improving the adhesion between the active material and the copper foil, but also the internal residual stress compared to the conventional roughened copper foil Therefore, the conductivity is increased and the battery negative electrode with less heat generation is obtained. In addition, since the active material composition is exposed to a high temperature of 300 ° C. during the application, drying, heating, and pressure pressing processes, the roughened particles in the base portion are sintered and fixed to the copper foil surface. .

Except for the above-mentioned discoloration plating, as disclosed in Japanese Patent Application Laid-Open No. 2007-270184, the roughening tank 2 is replaced with a conductive aqueous solution containing a polymer dispersion medium, and copper is applied to the surface of the untreated copper foil. A treatment for depositing nanoparticles can also be handled. When the copper particles become smaller and later formed into the negative electrode of the battery, the copper nanoparticles can come into contact with the active material without any gaps, so that the conductivity with the negative electrode current collector can be further improved.

In this embodiment, in the roughening treatment step, capsule plating is not performed after burnt plating as in the past. By not performing the capsule plating, the roughened particles are not fixed to the base metal foil, and the active material is pressed against the roughened particles by the pressure of the heating / pressurizing step (press) and moved, so that the roughened particles become active. It can move in a state where a part is taken into the active material layer along the shape of the material, and the contact area between the roughened particles and the active material is maximized. In the case of using copper foil to be encapsulated after the above conventional burnish plating, the roughened particles are fixed to the base metal foil. Therefore, even if the active material is pressed against the roughened particles by the pressure of the press, the roughened particles Cannot move, and a residual stress remains between the active material and the base metal foil. When the negative electrode of the battery is formed, the base metal foil is also broken.

As the active material in the present invention, in addition to the conventional graphite material, an active material that occludes lithium by alloying with a material that occludes and releases lithium can be selected. As such an active material, silicon, germanium, tin, lead, zinc, magnesium, sodium, aluminum, potassium, indium and the like are known. Among these, silicon or tin is preferred as a negative electrode active material in recent years because it is preferred because of its high theoretical capacity and ease of handling.

The negative electrode active material layer of the lithium ion secondary battery is preferably an active material layer containing silicon or tin as a main component in addition to graphite, and particularly preferably a layer containing silicon as a main component.
The active material layer is preferably an amorphous layer or a microcrystalline layer. When a silicon-based material is selected, the active material layer is preferably an amorphous silicon layer or a microcrystalline silicon layer.

This embodiment is based on the premise that the current collector is thin, and it is preferable that the secondary battery is lightweight and light in design. Accordingly, as the metal foil, copper foil is selected for the negative electrode current collector, and aluminum is selected for the positive electrode current collector. The active material layer is formed by coating and depositing on one surface or front and back surfaces of the current collector. When the active material layer is formed on the front and back of the current collector, the surface roughness Rz on both sides of the current collector is in the range of 0.5 to 5 μm, and the difference between the Rz values on the front and back is 2.5 μm or less. It is preferable.

The thickness of the current collector (metal foil) is preferably about 8 μm for a thin one and about 20 μm for a thick one. If the thickness is 8 μm or less, the strength of the foil (as a current collector) cannot be maintained, and crack fracture occurs when the active material expands and contracts. If the thickness exceeds 20 μm, the battery characteristics can be satisfied, but the battery itself is large and heavy.

The Rz values on the front and back surfaces are in the range of 0.5 to 5 μm. When the Rz value is lower than the lower limit, the adhesion due to the anchor effect with the active material layer becomes poor, and when the Rz value is higher than the upper limit value, the active material does not uniformly enter the concaves corresponding to the roughened irregularities, and the current collector and the active material This is not preferable because the adhesion of the layer becomes insufficient.
If the surface roughness is large between the front and back surfaces, the thickness of the active material is different on both sides in the active material coating process, which causes a problem in battery electrode characteristics. Therefore, the difference in the roughness Rz between the front and back sides is set to 2.5 μm or less. That is, when the difference in roughness Rz between the front and back surfaces is 2.5 μm or more, the thickness of the active material is different on both sides in the active material coating process, and sufficient battery electrode characteristics cannot be obtained.

The lithium ion secondary battery of the present invention comprises a negative electrode on which an active material layer mainly composed of graphite, silicon, or tin is applied and deposited as an active material for a lithium ion secondary battery; A positive electrode using a substance to be released, a nonaqueous electrolyte, and a separator are provided.

The non-aqueous electrolyte used in the lithium ion secondary battery of the present invention is an electrolyte in which a solute is dissolved in a solvent, and the solvent of the non-aqueous electrolyte is not particularly limited as long as it is a solvent used in a lithium ion secondary battery. Examples include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate, and chain carbonates such as dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. Preferably, a mixed solvent of cyclic carbonate and chain carbonate is used. Is used. A mixed solvent of a cyclic carbonate and an ether solvent such as 1,2-dimethoxyethane or 1,2-diethoxyethane, or a chain ester such as γ-butyrolactone, sulfolane, or methyl acetate may be used.

The solute of the nonaqueous electrolyte is not particularly limited as long as it is a solute used for a lithium ion secondary battery. For example, LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , LiAsF ₆ , LiClO ₄ , Examples include Li ₂ B ₁₀ Cl ₁₀ and Li ₂ B ₁₂ Cl ₁₂ .

As the non-aqueous electrolyte, a gel polymer electrolyte obtained by impregnating a polymer electrolyte such as polyethylene oxide, polyacrylonitrile, or polyvinylidene fluoride with an electrolytic solution, or an inorganic solid electrolyte such as LiI or Li ₃ N can be used.

The electrolyte of the lithium ion secondary battery of the present invention can be used without restriction unless it is decomposed by the voltage at the time of charge / discharge or storage.

As the positive electrode active material used for the positive _electrode, and _{_{LiCoO 2, LiNiO 2, LiMn 2}} O4, LiMnO 2, LiCo 0.5 Ni 0.5 O 2, LiNi 0.7 Co 0.2 Mn 0.1 lithium-containing transition metal oxides such as O _2, MnO Examples of the metal oxide that does not contain lithium such as ₂ can be used without limitation as long as the material can accept and release lithium ions in the battery.

According to the present invention, when the active material mixture is applied, conductive metal fine particles (dropped roughening treatment layer) are mixed in the active material layer in a drying / pressurizing process and the like, and appropriately dispersed in the active material layer. The conductivity of the active material layer is improved, and the negative electrode current collector can be prevented from wrinkling and cracking during charging / discharging, and the energy density per volume of the lithium ion secondary battery is increased and stable for a long time. A lithium ion secondary battery that maintains the performance can be provided.

When winding the metal foil with an active material layer in the embodiment shown in FIGS. 11 and 15, a film (separator) is interposed to protect the surface of the active material layer overlapped.
As described above, since a film is present on one surface, when the metal foil with an active material layer is wound up, an accident in which the active material layers are in contact with each other and possibly damaged can be prevented. .
Moreover, when this metal foil with an active material layer is used as an electrode of a secondary battery, if the film is made of the same material as the battery electrode separator, the separator can be shared as an electrode, and there is no need to remove it.
In addition, it is preferable to use a release paper as the film except that the separator is used as an electrode.
The battery separator is an important material that separates the positive electrode and the negative electrode in the battery and retains the electrolytic solution to ensure the ionic conductivity between the positive electrode and the negative electrode. Although the type of separator varies depending on the battery, microporous membranes made of polyethylene (ultra-high molecular weight PE) or polypropylene (PP) are used for lithium ion batteries. There are three types of layer structure, PP / PE / PP. Depending on the characteristics of the glass transition point (TG) of these resins, it is necessary to set the drying temperature and the heating and pressing conditions to be equal to or lower than the glass transition point (TG) temperature of the resin. In this embodiment, polyethylene (ultra high molecular weight PE) is used.

Hereinafter, although one embodiment of the present invention will be described in detail in an example using an electrolytic copper foil as an example, the present invention is not limited to the following example in any way, and may be applied to a metal foil other than a copper foil. The present invention can be implemented with appropriate modifications within a range not changing the gist thereof.
[Examples 1 to 3 and Comparative Example 1]

[Manufacture of electrolytic copper foil]
Examples 1 and 4 and Comparative Example 1
In this embodiment, copper foil is used as the metal foil.
70 to 130 g / l as electrolytic mother liquor metal foil for foil making,
80-140 g / l as sulfuric acid
An electrolytic solution for foil production was prepared by adding MPS, HEC and chloride ions having the composition shown in Table 1 as additives to the acidic copper electrolytic bath. In the table, MPS is sodium 3-mercapto-1-propanesulfonate, HEC (high molecular polysaccharide) is hydroxyethyl cellulose, and glue is a low molecular weight glue having a molecular weight of 3000.
Although the chloride ion concentration was adjusted to 30 ppm, the chloride ion concentration is appropriately changed depending on the electrolysis conditions, and is not limited to this concentration.

Foil Production Using the prepared electrolytic mother liquor, using a noble metal oxide-coated titanium electrode as the anode and a titanium rotating drum as the cathode, an electrolytic copper foil having a thickness of 10 μm was prepared under the electrolysis conditions (current density, liquid temperature) shown in Table 1. Made foil. Table 2 shows the surface roughness Rz and mechanical properties of the electrolytic copper foil that was made.

In addition, each measured value shown in Table 2 is a value measured as follows.
[Measurement of foil thickness, tensile strength (TS), elongation (E)]
These are actual values measured with a micrometer, and tensile strength (TS) and elongation (E) are values measured using a tensile tester (type 1122 manufactured by Instron). The surface roughness Rz is a value measured with a stylus type surface roughness meter (SE-3C type manufactured by Kosaka Laboratory).

[Roughening of metal foil surface]
The front and back surfaces of the 10 μm electrolytic copper foil produced under the above-mentioned foil making conditions were subjected to copper burn plating under the following conditions using the apparatus shown in FIG.
That is, in Example 1, the electrolytic copper foil made as described above was subjected to surface treatment under the following burnt plating conditions using the feeding roll 20 shown in FIG. 8 as an anode and the feeding electrode 20 arranged in the treatment layer 2 as a cathode, and then treated in the treatment tank. 4. Wash with water. Although the tank 4 for water washing shows one tank in FIG. 8, you may increase the tank for water washing as needed. Next, if necessary, in a subsequent drying step, the rust prevention treatment tank 5 may be spread and rust prevention treatment may be performed so that the copper foil is not discolored and lightly dried before slurry application.
Table 3 shows the characteristic values after applying the roughened particles.
Table 3 shows the characteristic values after applying the roughening particles by the burnt plating.

Surface roughening treatment (bake plating) conditions:
22.5 to 24.0 g / l as metallic copper
90-120 g / l as sulfuric acid
The additive metal is 0.35 g / l as Mo.
Bath temperature 18-30 ° C
Current density 25-35A / dm ²
Treatment time 2.5 to 7.5 seconds Note that typical examples of the additive metal include Fe, Ni, Cr, W, and V. A plurality of the metals may be selected and added.

In Example 4, the feed roll shown in FIG. 8 was used as a cathode and the feed electrode 20 was used as an anode, and roughening was performed under the following conditions.
Surface roughening conditions In normal electrolytic copper plating solution (copper sulfate 40-250 g / l, sulfuric acid 30-210 g / l, hydrochloric acid 10-80 ppm, additives such as brightener specified by the manufacturer) The temperature was kept at 18 to 32 ° C., and the current density was 1 A / dm ² or more.
When the current density was lower than 1 A / dm ^2, it was found that the amount of copper plating was too small and almost no copper fine particles were deposited. Therefore, Example 4 was performed at 8 A / dm ² . If the current density is increased, a large amount of copper fine particles are precipitated. Therefore, if necessary, the amount of copper fine particles deposited may be controlled by controlling the current density.

Examples 2 and 3
In Examples 2 and 3, rolled copper foil was used, and the same surface treatment as in Example 1 was performed on the copper foil.
Example 2 and Comparative Example 2
In this example, a low roughness rolled copper foil (Tough Bitch) manufactured by Nippon Foil Co., Ltd. was used.
Example 3
In this example, a copper alloy foil (C14410) containing tin (0.15 wt%) manufactured by Nippon Foil Co., Ltd. was used.

Example 4
In Example 4, the same electrolytic copper foil as used in Example 1 was used. The feeding roll 0 was a cathode, the feeding electrode 0 was an anode, and copper fine particles (0.1 μm) were used under the same surface roughening treatment conditions as in Example 1. ~ 3.5 μm) is produced on the foil surface and then washed in the treatment tank 4 with water. Although the tank for water washing shows one tank in FIG. 2, you may increase the tank for water washing as needed. Next, if necessary, a rust prevention treatment tank 5 may be provided to prevent the copper foil from discoloring in a subsequent drying step, and the rust prevention treatment may be performed and lightly dried before slurry application.
The characteristic values after the application of the roughened particles are also shown in Table 3.

[Measurement of Rz value, surface area, crystal grain size]
The Rz values of the front and back surfaces of the copper foil were measured with an SE-3C type measuring instrument manufactured by Kosaka Laboratory, and the surface area of the copper foil after the roughening particle application treatment was measured using VK-8500 manufactured by KEYENCE. The grain size of the crystal structure of the cross section was judged by visual observation of an SEM image taken with a scanning electron microscope.

Active Material Granulation Silicon (SiO) was employed as the active material, and silicon (SiO), acetylene black, PVDF (polyvinylidene fluoride), and NMP (N-methyl-2-pyrrolidone) were mixed to form a slurry.
Formation of active material layer The active material in the form of a slurry was used as a current collector for the copper foils of the examples and comparative examples, and coated on the current collector, heated and dried, and heated and pressed to form a silicon-based deposited layer. A copper foil with an active material layer was prepared as (active material layer).
The active material mixture was adjusted to a suitable slurry viscosity with a demonstrable solvent so that it could be easily applied by a curtain coater. Moreover, although the method of apply | coating an active material mixture with a curtain coater was employ | adopted, the application method by the other roll etc. can also be applied for the application method.

According to the method for producing a metal foil with an active material layer, a thickener or a conductive aid for adjusting the viscosity is added and kneaded as necessary, with the active material and binder as main components. The kneaded active material mixture is applied to the surface of the metal foil on which the metal particles are deposited, and after drying, the metal particles and the active material are in strong contact with each other by a hot roll press. As a result, the contact resistance between the active material layer and the current collector (metal foil) can be reduced. In addition, since a part of the roughening treatment layer is blended as a conductive additive from the surface of the metal foil toward the inside of the active material layer, it has a gradient in which the conductivity decreases from the surface of the metal foil toward the inside of the active material layer. Therefore, the contact area with the metal foil can be increased to the maximum as compared with the copper foil subjected to normal cup cell plating, and can contribute to cycle characteristics as a battery.

The assembly and evaluation of the negative electrode current collector were performed under the following conditions.

[Preparation of beaker cell]
A three-electrode beaker cell was produced in a glove box under an argon gas atmosphere using the produced negative electrode current collector as an electrode. The beaker cell was configured by immersing a counter electrode (positive electrode), a working electrode (negative electrode), and a reference electrode in an electrolytic solution placed in a glass container.
As the electrolytic solution, an electrolytic solution in which 1 mol / liter of LiPF ₆ was dissolved in a solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 3: 7 was used. Lithium metal was used as the counter electrode and the reference electrode.

Evaluation of charge / discharge cycle characteristics After charging the beaker cell produced as described above at a constant current of 4 mA in a 25 ° C. environment until the potential of the working electrode (negative electrode) reaches 0 V (vs. Li / Li +). The discharge was performed at a constant current of 4 mA until the potential of the working electrode reached 2 V (vs. Li / Li +), and the discharge capacity retention rate after 100 cycles of charge / discharge efficiency was evaluated.
The evaluation results are also shown in Table 3.
Moreover, the result confirmed about the presence or absence of the crack fracture of the copper foil after repeating 300 cycles charging / discharging was written together in Table 3.

As shown in Table 3, in the current collector of Example 1, the difference in Rz value of the base copper foil was within the reference value, and the particle size and surface area of the roughened particles after the application of the roughened particles were also within the standard values. It was.
The evaluation of the charge / discharge cycle characteristics in the beaker cell battery prepared using the copper foil of Example 1 as a current collector is all satisfactory, and the current collector after 300 cycles of charge / discharge is also cracked and broken. I couldn't see it.

In Examples 2 and 3, a rolled copper foil is used as the base copper foil, the same roughening treatment as that of the electrolytic copper foil in Example 1 is performed, and the roughened rolled copper foil is used as a current collector. The battery was assembled and the battery characteristics were evaluated. The results are shown in Table 3 together with Example 1.

On the other hand, Comparative Example 1 used the same untreated copper foil as Example 1, but the difference in roughness Rz value between both surfaces after the roughening treatment was large, and thus the discharge capacity retention after 100 cycles of charge / discharge efficiency was high. It became unsatisfactory.
Moreover, in the comparative example 1, the crack fracture | rupture was seen by the collector after repeating 300 cycles charging / discharging.

According to the present invention, it is possible to increase the energy density per volume of the lithium ion secondary battery, to suppress the occurrence of deformation such as wrinkles and crack fracture of the current collector during charging and discharging, It is possible to provide a lithium ion secondary battery that can be downsized with a long lifetime in which the capacity does not decrease even when the discharge cycle is repeated.

DESCRIPTION OF SYMBOLS 1 Metal foil 2 Surface roughening processing tank 3 Roughening metal layer 4 Water washing processing tank 5 Rust prevention processing tank 6 Hopper 7 Hopper 8 Active material mixture 9 Drying apparatus 10 Drying apparatus 11 Press 12 Winder 13 Film 14 Film supply apparatus DESCRIPTION OF SYMBOLS 15 Film supply apparatus 16 Laminating apparatus 20

Feeding electrode

22, 24, 26

Electrode

31, 32 Active material layer 33 Active material 35 Metal particle 37 Binder (conductive material)

Claims

A metal foil with a coating layer in which a coating layer is provided on at least one side of the metal foil, and the coating layer contains free metal particles.
The metal foil with a coating layer according to claim 1, wherein the coating layer is a remeltable resin composition containing free metal particles.
The metal foil with a coating layer according to claim 1, wherein the coating layer is an active material layer containing free metal particles.
The metal foil with a coating layer according to claim 1, wherein the coating layer is a remeltable resin composition layer containing free metal particles, and an active material layer is provided on the resin composition layer.
A metal foil with a coating layer in which a roughening treatment layer is provided on at least one surface of the metal foil, a coating layer is provided on the roughening treatment layer, and free metal particles are contained in the coating layer.
The metal foil with a coating layer according to claim 5, wherein the free metal particles contained in the coating layer are metal particles released from the roughening treatment layer.
The metal foil with a coating layer according to claim 5 or 6, wherein the coating layer is a remeltable resin composition.
The metal foil with a coating layer according to claim 5 or 6, wherein the coating layer is an active material layer.
The metal foil with a coating layer according to claim 5 or 6, wherein the coating layer is a remeltable resin composition layer, and an active material layer is provided on the resin composition.
The metal foil with a coating layer according to any one of claims 1 to 9, wherein the metal foil is an electrolytic copper foil or a rolled copper foil.
10. The metal foil with a coating layer according to claim 1, wherein a particle diameter of the free metal particles is 0.05 μm to 3.5 μm.
The roughening treatment layer according to any one of claims 5 to 9, wherein the roughening treatment layer is a roughening treatment layer containing at least one metal of copper, nickel, manganese, iron, chromium, tungsten, molybdenum, vanadium, and indium. Metal foil with coating layer.
10. A metal foil with a coating layer in which a film or a release paper is provided on at least the outermost layer surface of the metal foil with a coating layer according to claim 1.
An electrode for a secondary battery in which an active material layer is provided on at least one surface of a metal foil, and the active material layer contains free metal particles.
An electrode for a secondary battery in which a remeltable resin composition layer containing free metal particles is provided on at least one surface of a metal foil, and an active material layer is provided on the resin composition layer.
An electrode for a secondary battery in which a roughening treatment layer is provided on at least one surface of a metal foil, an active material layer is provided on the roughening treatment layer, and free metal particles are contained in the active material layer.
The secondary battery electrode according to claim 16, wherein the free metal particles contained in the active material layer are metal particles released from the roughening treatment layer.
A roughened layer is provided on at least one surface of the metal foil, a remeltable resin composition layer containing free metal particles is provided on the roughened layer, and an active material layer is provided on the resin composition layer. A secondary battery electrode.
The secondary battery electrode according to claim 16, wherein the free metal particles contained in the remeltable resin composition layer are metal particles released from the roughening treatment layer.
The secondary battery electrode according to any one of claims 14 to 17, wherein the metal foil is an electrolytic copper foil or a rolled copper foil.
The secondary battery electrode according to any one of claims 14 to 17, wherein a particle diameter of the free metal particles is 0.05 µm to 3.5 µm.
The roughening treatment layer is a roughening treatment layer treated with a plating bath containing at least one metal of copper, nickel, manganese, iron, chromium, tungsten, molybdenum, vanadium, and indium, and Heisei. Item 18. The secondary battery electrode according to any one of Items 14 to 17.
A secondary battery electrode comprising a film or a release paper provided on at least the outermost layer surface of the secondary battery electrode according to any one of claims 14 to 18.
The secondary battery electrode according to claim 21, wherein the film is a battery separator.
A method for producing a metal foil with a coating layer, wherein a coating layer is provided on at least one side of the metal foil, and the coating layer contains free metal particles,
Electrolytic plating is applied to the surface of the metal foil to apply a roughening treatment layer having a particle size of 0.1 μm to 3.5 μm by passing a current exceeding the limit current density.
Forming a coating layer on the roughened layer;
The manufacturing method of the metal foil with a coating layer which mixes a part of said roughening process particle | grains as a free metal particle in a coating layer.
The method for producing a metal foil with a coating layer according to claim 23, wherein the coating layer is a remeltable resin composition layer.
The method for producing a metal foil with a coating layer according to claim 23, wherein the coating layer is an active material layer.
The method for producing a metal foil with a coating layer according to claim 23, wherein the coating layer is a remeltable resin composition layer, and an active material layer is provided on the resin composition layer.
A method for producing a metal foil with a coating layer, wherein a coating layer is provided on at least one side of the metal foil, and the coating layer contains free metal particles,
The surface of the metal foil is electrolytically plated, a current exceeding the limit current density is applied, and a roughening treatment layer having a particle size of 0.1 μm to 3.5 μm is applied.
On the roughened layer, an active material mixture obtained by adding and mixing an active material, a binder, and, if necessary, a thickener and a slurry is applied to form an active material layer,
The metal foil on which the active material layer is formed is dried and pressurized so as to incorporate the metal-treated particles into the active material layer as a conductive additive,
The manufacturing method of the metal foil with a coating layer which makes the active material layer contain the said roughening process particle | grains as a free metal particle.
A method for producing a metal foil with a coating layer, wherein a coating layer is provided on at least one side of the metal foil, and the coating layer contains free metal particles,
Electrolytic plating is applied to the surface of the metal foil to apply a roughening treatment layer having a particle size of 0.1 μm to 3.5 μm by passing a current exceeding the limit current density.
Forming a remeltable resin composition layer on the roughened layer,
On the resin composition layer, an active material layer is formed by applying an active material mixture in which an active material, a binder, and, if necessary, a thickener and a slurry are added and mixed,
A method for producing a metal foil with a coating layer, wherein the metal foil on which the resin composition layer and the active material layer are formed is dried and pressed so that the roughened particles are incorporated into the resin composition layer as free metal particles.
An electrode for a secondary battery using a metal foil produced by the method for producing a metal foil with a coating layer according to any one of claims 23 to 28.
A surface roughening treatment step of forming a roughening treatment layer having a particle size of 0.1 μm to 3.5 μm by passing an electric current exceeding a limit current density by electrolytic plating on the surface of the metal foil;
An active material granulating step of adding and mixing an active material, a binder, and, if necessary, a thickener and a slurry;
A first active material film forming step of applying the active material mixture granulated in the active material granulation step on one surface of the roughened layer;
A second active material film forming step of depositing the active material mixture on a film and laminating it on the other surface of the metal foil;
The metal foil in which the active material layer is formed in the first and second steps is dried and pressurized so that the roughened particles are taken into the active material layer as a conductive additive, and the roughened particles are used as free metal particles. The manufacturing method of the electrode for secondary batteries which consists of the drying pressurization process contained in an active material layer.
A surface roughening treatment step of forming a roughening treatment layer having a particle diameter of 0.1 μm to 3.5 μm by passing an electric current exceeding a limit current density by electrolytic plating on the surface of the metal foil;
A resin composition layer forming step of forming a remeltable resin composition layer on the roughened layer;
An active material granulating step of adding and mixing an active material, a binder, and, if necessary, a thickener and a slurry;
A first active material film forming step of applying the active material mixture granulated in the active material granulation step on one surface of the resin composition layer;
A second active material film forming step of depositing the active material mixture on a film and laminating it on the other surface of the resin composition layer;
The metal foil in which the active material layer is formed in the first and second steps is dried and pressurized so that the roughened particles are taken into the active material layer as a conductive additive, and the roughened particles are used as free metal particles. The manufacturing method of the electrode for secondary batteries which consists of the drying pressurization process contained in an active material layer.
The metal foil according to any one of claims 1 to 13, the metal foil produced by the production method according to any of claims 23 to 28, or the secondary electric power according to any of claims 14 to 22. A lithium ion secondary battery using an electrode or an electrode produced by the production method according to any one of claims 30 to 31.