TW201320454A - Metal foil with coating layer and method for producing same, secondary cell electrode and method for producing same, and lithium ion secondary cell - Google Patents

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, manufacturing method thereof, electrode for secondary battery, manufacturing method thereof and lithium ion secondary battery

The present invention relates to a metal foil having a coating layer which is used as an electrode for a lithium ion secondary battery and which is relatively good.

Furthermore, the present invention relates to a secondary battery electrode using the above-described metal foil having a coating layer, and a lithium ion secondary battery using the same.

Lithium-ion secondary batteries are used as an indispensable power source for mobile phones, small portable data collectors, and notebook computers. The current collector of the negative electrode of the lithium ion secondary battery generally uses a copper foil. The formation of the negative electrode current collector is performed by coating carbon particles as a negative electrode active material layer on the surface of the copper foil which is smooth on both sides, and then pressing to form a negative electrode.

The negative electrode current collecting system for a lithium ion secondary battery uses a copper foil having a small difference in surface roughness between the two surfaces, that is, a so-called rolled copper foil. Recently, the manufacturer has directed an electrolytic copper foil having a small difference in surface roughness between the two surfaces. A technique for suppressing problems such as a decrease in the charge and discharge efficiency of the battery has been actively carried out (see Patent Document 1).

An electrolytic copper foil having a small difference in surface roughness between the two surfaces is prepared by appropriately selecting a water-soluble polymer substance, a surfactant, an organic sulfur compound, a chloride ion, or the like, and adding it in a small amount. A well-known representative technique, for example, a compound having a hydrogenthio group, a chloride ion, a low molecular weight gel having a molecular weight of 10,000 or less, and a polymer polysaccharide, which are prepared by adding an electrolytic copper foil to the electrolyte. Manufacturing method (refer to Patent Document 2).

The electrolytic copper foil (current collector) produced by the production method is coated with black lead particles as an active material and a binder on both surfaces, and then heated and pressure-bonded to form copper having an active material. A foil is used as a negative electrode for a lithium ion secondary battery.

In recent years, in order to achieve a high capacity of a lithium ion secondary battery, a lithium ion secondary battery using a ruthenium, osmium, tin, or the like which can be electrochemically alloyed with lithium during charging has been proposed as a negative electrode active material. (Refer to Patent Document 3).

The negative electrode for a lithium ion secondary battery for the purpose of increasing the capacity is formed by depositing, for example, an amorphous ruthenium film and a microcrystalline ruthenium film on a base metal foil produced by a CVD method or a sputtering method. Since the thin film layer of the active material formed by the above method is in close contact with the current collector, the surface can be well charged and discharged (see Patent Document 4).

Further, in recent years, the industry has also developed a method for forming an electrode by forming a slurry of a tantalum powder and a melamine-based binder together with an organic solvent, coating, drying, and pressing on a copper foil. However, the powdery bismuth and tin generally have a small particle diameter of 0.1 to 3 μm, and it is difficult to apply a coating having an appropriate adhesion with a uniform thickness on both sides of the metal foil as the negative electrode current collector. The coating efficiency is not good.

Further, in the negative electrode for a lithium ion secondary battery, for example, the ruthenium active material absorbs lithium ions at the time of charging, and its volume expands by a maximum of about four times, and at the time of discharge, lithium ions are released and contracted. By the expansion and contraction of the volume of the active material accompanying charging and discharging, not only the problem that the active material is peeled off from the current collector but also the phenomenon that the current collector has stress or the like occurs.

An electrode including a metal foil having an active material layer having a large expansion and contraction is included in the battery. When the charge and discharge are repeated several times, the current collector (metal foil) is similarly shrunk, so that wrinkles are easily generated inside. In order to allow wrinkles, it is necessary to design the volume occupied by the electrodes in the battery to have a space elasticity, but relatively, there is a problem that the energy density per unit volume (charge and discharge capacity) is lowered.

In order to increase the energy density (charge and discharge capacity) per unit volume, the elasticity of the expansion and contraction of the current collector is reduced, causing the current collector to be unable to withstand internal stress and being broken, and it is impossible to maintain stable battery characteristics and the like.

Conventional technical literature

Patent literature

Patent Document 1: Japanese Patent No. 3742144

Patent Document 2: Japanese Patent No. 3313277

Patent Document 3: Japanese Patent Laid-Open Publication No. 10-255768

Patent Document 4: Japanese Patent Laid-Open Publication No. 2002-083594

Patent Document 5: Japanese Patent Showa No. 53-39376

When a metal foil having an electrode for a lithium ion secondary battery replaced with black lead and coated with an active material containing ruthenium, osmium, or tin as a main component is used as an electrode, with charging In the discharge reaction, the volume of the active material layer will expand and contract, causing the collector (metal foil) to withstand considerable stress and causing wrinkles and the like of the current collector. And when charging When the discharge is repeated a plurality of times, a small number of collectors may have a problem of fracture. When the current collector is physically deformed such as wrinkles, the area occupied by the electrodes in the battery is somewhat increased, and as a result, the energy density per unit volume is lowered.

Further, when the current collector is cracked/cracked, it is not only impossible to maintain the performance of the battery for a long period of time, but also a problem that the charge and discharge characteristics (cycle characteristics) are lowered.

Further, when the active material is coated and stacked, since the particle size of ruthenium and tin is small, when it is applied to the negative electrode current collector in a slurry form, it is difficult to form a uniform thickness on both sides. It has a suitable adhesion to coat and the coating efficiency is not good. In particular, when the difference in surface roughness between the front and back surfaces of the current collector is increased, it is more difficult to apply a uniform thickness of the active material on both the front and back sides. When the application of the active material is not performed uniformly, it will adversely affect the output characteristics and cycle characteristics of the battery.

Therefore, the main object of the present invention is to provide a lithium ion secondary battery which is used for coating and stacking a negative electrode formed by stacking an active material such as ruthenium, osmium or tin as a main component on a current collector. In a lithium ion secondary battery, the current collector will not cause wrinkles and the like, and the current collector will not be broken, and not only the adhesion between the active material and the current collector will increase, but also the stability can be maintained for a long time. Secondary battery characteristics. Further, an object of the present invention is to provide a metal foil as the current collector for a secondary battery electrode, and in particular to provide an electrolytic copper foil.

Meanwhile, an object of the present invention is to provide a metal foil for a current collector of a secondary battery electrode, which is used not only as a copper foil but also as a current collector for a lithium ion secondary battery for the same purpose as the above-mentioned electrolytic copper foil. Metal foil, Like the copper foil, wrinkles are not generated in the current collector, and the breakage of the current collector does not occur, and not only the adhesion between the active material and the current collector is increased, but also the stable secondary battery can be maintained for a long time. characteristic.

Further, an object of the present invention is to reduce the difference in electrical conductivity between the interface between the metal foil for a current collector of a lithium ion secondary battery electrode and an active material, to improve the conductivity of the active material layer, and to improve lithium ion II. The energy density per unit volume of the secondary battery.

Further, an object of the present invention is to provide a lithium ion secondary battery which is formed by coating and stacking an active material having a main component such as ruthenium, iridium or tin on a current collector (metal foil). The metal foil of the active material layer, the lithium ion secondary battery used as the electrode, does not wrinkle in the current collector, and the fracture of the current collector does not occur, not only between the active material and the current collector (metal The adhesion of the foil) is increased, and stable secondary battery characteristics can be maintained for a long time. Another object of the present invention is to provide a metal foil having an active material layer for the above secondary battery electrode.

In the metal foil having a coating layer of the present invention, a coating layer is disposed 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 containing free metal particles.

Further, the coating layer is preferably an active material layer containing free metal particles.

Preferably, the coating layer is a remeltable resin composition layer containing free metal particles, and an active material is preferably disposed above the resin composition layer. Floor.

A metal foil having a coating layer comprising: a roughening treatment layer disposed on at least one surface of the metal foil; and a coating layer disposed on the roughening treatment layer, wherein the coating layer contains free metal particles.

The metal foil with a coating layer of the present invention includes: a roughened layer disposed on at least one surface of the untreated metal foil; and a coating layer disposed on the roughened layer, wherein the coating layer contains free metal particle.

The free metal particles contained in the coating layer are preferably metal particles liberated from the roughened layer.

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

Further, the coating layer disposed on the roughening treatment layer is preferably an active material layer.

Further, the coating layer disposed on the roughening layer is preferably a remeltable resin composition layer, and an active material layer is disposed above the resin composition layer.

The particle diameter of the above free metal particles is preferably from 0.05 μm to 3.5 μm.

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

Preferably, a film or a release paper is disposed on the surface of at least the outermost layer of the metal foil having the coating layer.

The electrode for a secondary battery of the present invention, on at least one surface of the metal foil An active material layer is disposed, and the active material layer contains free metal particles.

In the electrode for a secondary battery of the present invention, a remeltable resin composition layer containing free metal particles is disposed on at least one surface of the metal foil, and an active material layer is disposed on the resin composition layer.

In the electrode for a secondary battery of the present invention, it is preferable that a roughening treatment layer is disposed on at least one surface of the metal foil, and an active material layer is disposed on the roughening treatment layer, and the active material layer contains free metal particles.

In the electrode for a secondary battery of the present invention, a roughening treatment layer is disposed on at least one surface of the metal foil, and a remeltable resin composition layer containing free metal particles is disposed on the roughening treatment layer. An active material layer is disposed on the composition layer.

In the electrode for a secondary battery of the present invention, a roughening treatment layer is disposed on at least one surface of the metal foil, and a remeltable resin composition layer containing free metal particles is disposed on the roughening treatment layer. An active material layer is disposed on the composition layer.

The particle diameter of the above free metal particles is preferably from 0.05 μm to 3.5 μm.

The roughened layer is preferably a roughened layer formed by treating a plating bath containing at least one of copper, nickel, manganese, iron, chromium, tungsten, molybdenum, vanadium, and indium.

On the surface of at least the outermost layer of the electrode for a secondary battery, a film or a release paper is preferably disposed.

A method for producing a metal foil having a coating layer according to the present invention is a method for producing a metal foil having a coating layer containing at least one surface of an untreated metal foil, wherein the coating layer contains free metal particles, and a coating method a method for forming a roughened layer having a particle diameter of 0.1 μm to 3.5 μm by using a plating bath and a current exceeding a limiting current density on a surface of the metal foil; forming a coating layer on the roughened layer; A part of the roughened particles are mixed in the coating layer as free metal particles.

The coating layer is preferably a remeltable resin composition layer.

Further, the coating layer is preferably an active material layer.

Further, the coating layer is preferably a remeltable resin composition layer, and an active material layer is preferably disposed on the resin composition layer.

A method for producing a metal foil having a coating layer according to the present invention is a method for producing a metal foil having a coating layer containing at least one surface of an untreated metal foil, wherein the coating layer contains free metal particles, including : on the surface of the metal foil, using a plating bath and passing a current above a limiting current density to form a roughened layer having a particle diameter of 0.1 μm to 3.5 μm; on the roughened layer, the coating is added with an active layer a substance, a binder, and a mixture of active materials mixed with a slurry or the like may be added as necessary to form an active material layer; and the metal foil on which the active material layer is formed is dried and pressurized. The metal-treated particles are introduced into the active material layer as a conductive auxiliary agent, and the roughened particles are contained in the active material layer as free metal particles.

In the method for producing a metal foil having a coating layer according to the present invention, a coating layer is disposed on at least one surface of the metal foil, and the coating layer includes a metal foil having a coating layer of free metal particles, and a plating tank is used for the surface of the metal foil. And passing a current above a limiting current density to form a roughened layer having a particle diameter of 0.1 μm to 3.5 μm; on the roughened layer, a resin composition layer; an active material mixture in which an active material, a binder, a tackifier, and a slurry are added to the resin composition layer to form an active material; The material layer; and the metal foil having the resin composition layer and the active material layer formed thereon are dried and pressurized to bring the roughened particles into the resin composition layer to form free metal particles. Although the embodiment of the present invention uses cathodic electroplating, the same effect can be obtained by anodic electroplating.

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

The electrode for a secondary battery of the present invention is a current collector using a metal foil produced by the above-described method for producing a metal foil having a coating layer.

A method for producing an electrode for a secondary battery according to the present invention comprises: a surface roughening treatment step of forming a particle diameter of 0.1 μm by using a plating bath and a current exceeding a limit current density on an untreated metal foil surface; 3.5 μm roughening treatment layer; active material granulation step, adding active material, binder, if necessary, adding tackifier, and slurry, etc.; mixing; first active material layer forming step, in the above roughening treatment a surface of one of the layers coated with the active material mixture produced in the granulation step of the active material; a second active material layer forming step of laminating the active material mixture on the film and laminating it on the metal foil And drying and pressurizing the metal foil having the active material layer formed in the first and second steps, and drying, to bring the roughened particles into the active material In the layer, as the conductive auxiliary agent, the roughened particles are contained as free metal particles in the active material layer.

A method for producing an electrode for a secondary battery according to the present invention includes a surface roughening treatment step (hereinafter referred to as "scorch plating"), and a surface of the metal foil is formed by using a plating bath and a current having a limit current density or more to form a pellet a roughening treatment layer having a diameter of 0.1 μm to 3.5 μm; a resin composition layer forming step, forming a resin composition layer on the roughening treatment layer; an active material granulation step, adding an active material, a binder, and adding if necessary a tackifier, a slurry, and the like; a first active material layer forming step, coated on the surface of one of the resin composition layers, and coated with the active material mixture produced in the active material granulation step; a second active material layer forming step of laminating the active material mixture on the film and laminating on the other surface of the resin composition layer; and drying and pressurizing the step, having the first step and the second step The metal foil of the formed active material layer is dried and pressurized to bring the roughened particles into the active material layer to serve as a conductive auxiliary agent, and the above roughening Physical particles as free metal particles contained in the active material layer.

The above resin composition is preferably a remeltable resin composition.

The lithium ion secondary battery of the present invention is a secondary battery in which the above electrodes are assembled.

In the metal foil having a coating layer of the present invention, since a coating layer of a remeltable resin composition layer in which free metal ions are mixed is formed on the surface of the metal foil, for example, adhesion between the active material layers formed on the surface of the coating layer can be improved. Further, it has an excellent effect of alleviating electrolysis or the like between the metal foil and the active material layer.

According to the metal foil for a current collector of the lithium ion secondary battery electrode of the present invention, when the metal foil is used as a current collector, since the metal constituting the roughened layer is mixed into the active material layer, conductivity can be improved, and It also has an effect of increasing the energy density per unit volume of the lithium ion secondary battery.

Further, when the metal foil of the present invention is used as a current collector, occurrence of wrinkles or the like due to expansion and contraction of the active material generated during charge and discharge can be suppressed, and the unit volume of the lithium ion secondary battery can be improved. Energy density. Further, the present invention can provide a current collector of a lithium ion secondary battery electrode having a current collector which is not broken by stress and which has an increased output force due to an increase in the adhesion between the active material and the current collector. Use metal foil.

In the lithium ion secondary battery of the present invention, since the metal foil is used for the negative electrode of the battery, the current collector does not wrinkle due to charge and discharge, and the energy density per unit volume of the lithium ion secondary battery can be increased. According to the present invention, it is possible to provide a lithium ion secondary battery electrode which has a stable output performance for a long period of time without causing breakage due to stress and an increase in adhesion between the active material and the current collector.

First embodiment

Hereinafter, a manufacturing flowchart of a metal foil having a coating layer according to the first embodiment of the present invention shown in Fig. 1 will be described.

Step 1 (Preparation of free metal particles)

Preparation of gold including copper, nickel, manganese, iron, chromium, tungsten, molybdenum, vanadium, indium Is a particle. The particle diameter of the metal particles is preferably in the range of 0.1 μm to 3.5 μm. The metal particles can be selected from one or a combination of two or more kinds depending on the conductivity of the following resin composition to be mixed.

Step 2 (Preparation of Remeltable Resin Composition)

A remeltable resin composition is prepared. As the remeltable resin composition, a commercially available thermoplastic resin composition (for example, polyvinylidene chloride resin (hereinafter referred to as PVDF)) and a thermosetting resin composition (for example, a thermosetting polyamidamide resin) can be used. ].

Further, in the present embodiment, it is preferable to provide an active material layer to be described later and a resin composition layer which can be subsequently provided on the resin composition layer.

Step 3 (Production of a conductive resin composition)

In the remeltable resin composition selected in the step 2, the free metal particles selected in the step 1 are mixed to prepare a conductive resin composition.

Step 4 (covered)

The resin composition of the metal particles prepared in the step 3 is coated on the surface of a metal foil (copper foil, aluminum foil, etc.). The coating method may be, for example, a method such as pressing, or a general method.

Specifically, a thermosetting resin composition using a thermosetting polyamidamide resin is dissolved in a solvent in a state in which free metal particles are added to the resin, and then applied to the surface of the metal foil, and thereafter, a solvent is used. Evaporation and drying are performed so that the thermosetting polyimide resin forms a B-stage resin, and a remeltable resin layer (B-stage resin) containing free metal particles is formed on the surface of the metal foil.

Alternatively, the resin composition containing the free metal particles is formed into a plate shape, and is pressed on the surface of the metal foil by press bonding or the like to form a metal foil having a coating layer.

In the above steps, a metal foil having a remeltable resin composition layer (coating layer) containing free metal particles can be produced.

2 is a cross-sectional view showing the metal foil 10 having a coating layer on which the refusible resin composition layers 11, 12 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, 12 are provided on both surfaces of the metal foil 10. If only a single surface can be satisfied, it is not necessary to provide a composition layer on both surfaces.

Second embodiment

Hereinafter, a manufacturing flowchart of a metal foil having a coating layer according to a second embodiment of the present invention shown in FIG. 3 will be described.

Step 21 (Preparation of free metal particles)

Metal particles including copper, nickel, manganese, iron, chromium, tungsten, molybdenum, vanadium, and indium are prepared. The particle diameter of the metal particles is preferably in the range of 0.1 μm to 3.5 μm. The metal particles may be selected from one or a combination of two or more depending on the conductivity of the active material layer to be mixed.

Step 22 (Step of producing active substance mixture)

The active material, the binder, and, if necessary, conductive carbon black, or a tackifier, and a slurry may be added to form an active material mixture. Further, when the active material mixture is formed, for example, polyimide as a binder may be mixed.

Step 23 (mixed)

In the active material mixture prepared in the step 2, the free metal particles in the step 1 are mixed to impart conductivity to the active material layer.

Step 24 (covered)

The coating and coating of the active material mixture prepared in the step 3 are carried out on a single surface of a metal foil (copper foil, aluminum foil, etc.) 30. The coating method can be, for example, a method such as press bonding, a general method, or the like.

In the above steps, a metal foil having a remeltable resin composition layer (coating layer) containing free metal particles can be produced.

4 is a cross-sectional view showing a metal foil having a coating layer on which a layer of the active material layer 32 is provided on a single surface of the metal foil 30. As shown in the figure, in the coating layer (active material layer) 32, the free metal particles 34 are dispersed in the gap of the active material 33.

In addition, FIG. 4 illustrates that the active material layer 32 is disposed on a single surface of the metal foil 30. If it is required to be disposed on both surfaces, the active material layer may be disposed on both surfaces of the metal foil in the following steps. .

Step 25 (covered)

Applying and coating the active material mixture of the step 3 on the other surface of the metal foil (copper foil, aluminum foil, etc.). The coating method can be, for example, a press-bonding method, a general method, or the like.

In the above steps, a metal foil having an active material layer (coating layer) containing free metal particles on a single surface or both surfaces can be produced.

Third embodiment

Hereinafter, a manufacturing flowchart of a metal foil having a coating layer according to a third embodiment of the present invention shown in FIG. 5 will be described.

Step 31 (Preparation of free metal particles)

Metal particles including copper, nickel, manganese, iron, chromium, tungsten, molybdenum, vanadium, and indium are prepared. The particle diameter of the metal particles is preferably in the range of 0.1 μm to 3.5 μm. The metal particles can be selected from one type or a combination of two or more types depending on the conductivity of the resin composition to be described later.

Step 32 (Preparation of Remeltable Resin Composition)

A remeltable resin composition is prepared. As the remeltable resin composition, a commercially available thermoplastic resin composition (for example, polyvinylidene chloride resin (hereinafter referred to as PVDF)) and a thermosetting resin composition (for example, a thermosetting polyamidamide resin) can be used. ].

Further, in the present embodiment, it is preferable to select an active material layer to be described later and a resin composition which can be attached to the resin composition layer.

Step 33 (mixed)

The metal particles selected in the step 31 are mixed in the remeltable resin composition selected in the step 32 to prepare a conductive resin composition.

Step 34 (covered)

On the surface of the metal foil (copper foil, aluminum foil, etc.), the coating of the metal particle resin composition is mixed in the step 3. The coating method can be, for example, a method such as press bonding, a general method, or the like.

Specifically, a thermosetting resin composition using a thermosetting polyamidamide resin is dissolved in a solvent in a state in which free metal particles are added to the resin, and then applied to the surface of the metal foil, and thereafter, a solvent is used. Evaporation and drying to form a thermosetting polyamido resin to form a B-stage resin, and to a metal A remeltable resin layer (B-stage resin) containing free metal particles is formed on the surface of the foil.

Step 35 (Step of producing active substance mixture)

The active material, the binder, and, if necessary, conductive carbon black, or a tackifier, and a slurry may be added to form an active material mixture. Further, when the active material mixture is formed, for example, polyimide as a binder may be mixed.

Step 36 (formation of active substances)

The active material layer is formed on the resin composition layer (coating layer) formed in the step 34 by using the active material mixture prepared in the step 35.

Fig. 6 is a cross-sectional view showing a metal foil having a resin composition layer provided on a single surface of the metal foil 30 and a coating layer of the active material layer 32 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 are also dispersed in the active material layer 32 thereon.

Further, in the figure, 37 is a binder.

4, the composition layer and the active material layer 32 are provided on a single surface of the metal foil 30, but if necessary, the composition layer and the active material may be disposed on both surfaces. Floor.

Step 37 (Production of Electrode)

A metal foil having the active material layer produced in the step 35 was used for the electrode.

Step 38 (Production of the battery)

The electrode prepared in the step 36 was fabricated into a battery having a positive electrode and a negative electrode.

Fourth embodiment

Hereinafter, a manufacturing flow chart of a metal foil having a coating layer according to a fourth embodiment of the present invention shown in FIG. 7 and a manufacturing apparatus shown in FIG. 8 will be described.

Step 41 (surface roughening treatment step)

As shown in FIG. 8, the metal foil 1 is introduced into the surface roughening treatment tank 2, and metal particles are grown on the surface of the metal foil 1 to form the roughened metal layer 3.

As shown in FIG. 8, the metal foil 1 is introduced into the surface roughening treatment tank 2 by the feeding electrode 20, and passes through the plating electrodes 22, 24, 26 disposed in the surface roughening treatment tank 2. In FIG. 8, the plating electrodes 22, 24, and 26 are disposed at three places to roughen the both surfaces of the metal foil 1, and if the roughening treatment is performed only on a single surface, the electrode 26 can be omitted, for example. The conditions of the roughening treatment and the like will be explained later.

Next, it is introduced into the water washing treatment tank 4 to perform water washing of the roughened metal layer 3.

The water-washed metal foil is further introduced into the rust-preventing treatment tank 5 to apply a rust preventive agent to the surface of the roughened metal layer 3. This rust-preventing treatment can be omitted if there is no concern about the oxidation of the roughened metal layer.

Step 42 (Preparation of Remeltable Resin Composition)

On the surface of the metal foil (copper foil, aluminum foil, etc.), the resin composition is coated on the surface of the roughened layer formed in step 2. The coating method may be, for example, a method such as pressing, or a general method. Here, as shown in FIG. 8, the resin composition is dissolved in a solvent, and the metal is roughened in step 41. The method of coating on the surface of the foil will be described.

As shown in FIG. 8, the resin composition was dissolved in a solvent and filled in the container 6. The metal foil provided with the rustproof layer is introduced into the container 6 (filled with the resin composition dissolved in the solvent), and a solution composed of the resin composition is applied onto the surface.

Step 43 (drying step)

After the resin composition is coated on the surface of the metal foil, the solvent is evaporated in the solvent evaporation device 8 to be dried.

Step 44 (rolling step)

The dried metal foil having the resin composition layer is taken up by a coiler 11. In the manufacturing step or the subsequent step, a part of the roughened particles are introduced into the resin composition, and as shown in FIG. 4, a remeltable resin layer containing metal particles may be formed on the surface of the metal foil ( B-stage resin).

The formation step of the remeltable resin composition layer in the step 42 will be described in further detail below with reference to FIG. The roughened layer formed by the above plating method is preferably subjected to a roughening treatment by scorching plating. The roughened layer of the burnt plating is subjected to an unsound state in which the roughened particles are easily peeled off (powder off) in this state. In this state, the metal foil may be immersed in a storage tank 6 of a solution formed by dissolving, for example, polyvinylidene chloride resin (hereinafter referred to as PVDF) in a solvent of 1-methyl-2-pyrrolidone (NMD). The weight ratio of PVDF can be controlled by appropriately adjusting the concentration of the solvent. Then, it is dried at a specific time required to evaporate the solvent, and the resin adhering to the surface of the metal foil does not fall off the roughened particles, and a roughened copper foil having a resin composition is formed.

Further, when the remeltable resin composition layer is a thermosetting polyimide resin, the polyamidene is adjusted in a weight ratio and dissolved in a suitable solvent, and the above-mentioned scorching is carried out in the same manner as described above. The copper foil in the roughened state of electroplating is immersed and passed through the container 6 of the solution. Thereafter, in order to form a thermosetting polyimine resin into a B-stage resin, the solvent is evaporated at a desired specific time, and dried to adhere to the surface of the copper foil. Thus, a metal foil having a coating layer in which roughened particles are mixed with a B-stage resin can be produced.

In the present invention, the resin composition is applied and dried on a dendritic roughened particle layer adhered in a fragile state. The dendritic roughened particles are destroyed during the coating of the resin composition, or during the expansion and contraction during drying, or in the subsequent steps, and the damaged particles are dispersed in the resin composition layer as shown in FIG. And enter the resin composition layer.

Fifth embodiment

Hereinafter, a manufacturing flow chart of a metal foil having a coating layer according to a fifth embodiment of the present invention shown in FIG. 9 and a manufacturing apparatus shown in FIG. 10 will be described.

Step 51 (surface roughening treatment step)

As shown in FIG. 9, the metal foil 1 is introduced into the surface roughening treatment tank 2, and metal particles are grown on the surface of the metal foil 1 to form the roughened metal layer 3.

As shown in FIG. 10, the metal foil 1 is introduced into the surface roughening treatment tank 2 by the feeding electrode 20, and passes through the plating electrodes 22, 24, 26 disposed in the surface roughening treatment tank 2. In FIG. 10, plating electrodes 22, 24, and 26 are disposed at three places to roughen both surfaces of the metal foil 1, If the roughening treatment is performed only on a single surface, the electrode 26 can be omitted, for example. The conditions of the roughening treatment and the like will be explained later.

Next, it is introduced into the water washing treatment tank 4 to perform water washing of the roughened metal layer 3.

The water-washed metal foil is further introduced into the rust-preventing treatment tank 5, and the surface of the roughened metal layer 3 is coated with a rust preventive agent. This rust-preventing treatment can be omitted if there is no concern about the oxidation of the roughened metal layer.

Step 52 (Step of producing active substance mixture)

The active material, the binder, and, if necessary, a conductive carbon black or a tackifier, and a slurry may be added to form the active material mixture 8, and then the active material mixture 8 is supplied to the storage tanks 6, 7.

When the active material layer is formed, it is preferred to use, for example, polymethyleneamine as a binder to form a homogeneous slurry coating layer.

Step 53 (first active material layer forming step)

If necessary, the surface of the metal foil subjected to the surface roughening treatment may be subjected to rustproof treatment by the rust-preventing treatment layer 5, and the active material mixture 8 may be uniformly flowed from the hopper 6 on the other surface, and then dried. Drying of the active material mixture 8 is performed to form the active material layer 31.

Step 54 (second active material layer forming step)

Next, the active material mixture 8 is uniformly flowed from the hopper 7 on the other surface, and then the active material mixture 8 is dried by the drying device 10 to form the active material layer 32.

Step 55 (drying ‧ pressurization step)

An active material having active material layers 31, 32 formed on both surfaces The metal foil of the layer is heated and pressurized by the press machine 11. By this heating and pressurizing step, the active material layers 31, 32 will be uniformly adhered to the surface of the metal foil, and thereby the pressing step forces the roughened particles to move, as shown in FIG. 4, which is not fixed to the base metal foil 1. The roughened metal particles will leave the base metal foil 1 and be dispersed into the active material layer 31 (32) to improve the electrical conductivity between the active material layer 31 (32) and the interface of the base metal foil 1. Further, in the figure, 33 is an active material, and 37 is a binder and a conductive material added as necessary. The characteristics of the roughened metal particle distribution are concentrated on the side of the base metal foil and are reduced toward the outermost surface of the active material layer.

Step 56 (rolling step)

The pressed and dried metal foil having the active material layer is taken up by the coiler 12, and then transported to the next electrode (step 47) and the battery (step 48).

Sixth embodiment

Hereinafter, a manufacturing flow chart of a metal foil having a coating layer according to a sixth embodiment of the present invention shown in FIG. 11 and a manufacturing flow chart shown in FIG. 12 will be described.

Step 61 (surface roughening treatment step)

As shown in FIG. 12, the metal foil 1 is introduced into the surface roughening treatment tank 2, and metal particles are grown on the surface of the metal foil 1 to form the roughened metal layer 3.

As shown in FIG. 12, the metal foil 1 is introduced into the roughening treatment tank 2 by the feeding electrode 20, and is passed between the plating electrodes 22, 24, 26 disposed in the roughening treatment tank 2. In FIG. 12, the electroplating electrode 22 is disposed at three places, 24 and 26, the roughening treatment is performed on both surfaces of the metal foil 1, and if the roughening treatment is performed only on a single surface, the electrode 26 can be omitted, for example. The conditions of the roughening treatment and the like will be explained later.

Next, it is introduced into the water washing treatment tank 4 to perform water washing of the roughened metal layer 3.

The water-washed metal foil is introduced into the rust-preventing treatment tank 5 to apply a rust preventive agent to the surface of the roughened metal layer 3. This rust-preventing treatment can be omitted if there is no concern about the oxidation of the roughened metal layer.

Step 62 (Step of producing active substance mixture)

The active material, the binder, and, if necessary, a conductive carbon black or a tackifier, and a slurry may be added to form the active material mixture 8, and then the active material mixture 8 is supplied to the storage tanks 6, 7.

When the active material layer is formed, it is preferred to use, for example, polymethyleneamine as a binder to form a homogeneous slurry coating layer.

Step 63 (first active material layer forming step)

If necessary, the surface of the metal foil subjected to the surface roughening treatment may be subjected to rust-preventing treatment by the rust-preventing treatment layer 5, and the active material mixture 8 may be uniformly flowed from the hopper 6 on the other surface to form an active material layer. 31. The surface of the active material layer 31 is provided by the film supply roller 15 and adhered to the plastic film or the release paper 13 (if the plastic film or the release paper does not need to be particularly distinguished, the two may only be the film 13 Express).

Step 64 (second active material layer forming step)

On the film 13 provided by the supply roller 14 of the film 13, the active material mixture 8 is uniformly flowed from the hopper 7 to the surface roughened portion. On the other surface of the metal foil, the active material mixture 8 carried by the film 13 is provided to form the active material layer 32.

Step 65 (drying, pressurizing step)

The metal foil having the active material layers on which the active material layers 31 and 32 are formed on both surfaces is passed through a dryer 9 and a press machine 11, and heated and pressurized. By this heating and pressurizing step, the active material layers 31, 32 are uniformly adhered to the surface of the metal foil, and by this pressurizing step, the metal particles of a part of the roughened metal layer 3 grown by the above surface treatment can be obtained. Bring into the active material layer. The step of bringing the free metal particles into the active material layer has been described in the fifth embodiment, and therefore will not be described again.

Step 66 (rolling step)

The pressed and dried metal foil having the active material layer is taken up by the coiler 12, and then transported to the next electrode and the battery.

In the present embodiment, the film 13 is provided on the active material layer 32. Therefore, when the coiler (for example, the spool) 12 is wound up, the active material layer 32 and the active material layer 32 do not directly contact each other, so that the active material layer is not damaged when wound up.

Further, the film can be used, for example, using the same separator as the electrode of the lithium ion secondary battery to reduce troubles in battery assembly. Further, when it is not necessary to cover the surface of the active material with a film, it may be removed after the drying step of the active material layer.

Seventh embodiment

Hereinafter, a manufacturing flow chart of a metal foil having a coating layer according to a seventh embodiment of the present invention illustrated in FIG. 13 and manufacturing as shown in FIG. 14 will be described. The device is explained.

Step 71 (surface roughening treatment step)

As shown in FIG. 13, the metal foil 1 is introduced into the surface roughening treatment tank 2, and metal particles are grown on the surface of the metal foil 1 to form a roughened metal layer 3.

As shown in FIG. 14, the metal foil 1 is introduced into the surface roughening treatment tank 2 by the feeding electrode 20, and passes through the plating electrodes 22, 24, 26 disposed in the surface roughening treatment tank 2. In FIG. 14, the plating electrodes 22, 24, and 26 are disposed at three places to roughen the both surfaces of the metal foil 1, and if the roughening treatment is performed only on a single surface, the electrode 26 can be omitted, for example. The conditions of the roughening treatment and the like will be explained later.

Next, it is introduced into the water washing treatment tank 4 to perform water washing of the roughened metal layer 3.

The water-washed metal foil is further introduced into the rust-preventing treatment tank 5, and the surface of the roughened metal layer 3 is coated with a rust preventive agent. This rust-preventing treatment can be omitted if there is no concern about the oxidation of the roughened metal layer.

Step 72 (step of forming the first remeltable resin composition layer)

A remeltable resin composition is provided on a single surface 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, the resin composition layer is preferably a resin composition which can be followed by the active material layer thereon.

As shown in Fig. 13, a film 40 of a remeltable resin composition is provided on a single surface of the metal foil 1, and the two are bonded by pressing the roller 41. It can be hot pressed if necessary.

Step 73 (Step of producing active substance mixture)

The active material, the binder, and, if necessary, a conductive carbon black or a tackifier, and a slurry may be added, and the active material mixture 8 is supplied to the storage tanks 6, 7.

When the active material layer is formed, the active material 31 is adhered to the metal foil 1 by the above-mentioned remeltable resin composition layer 40, and if necessary, for example, polybenzamine is preferably used as a binder to form a homogeneous slurry. Coating layer.

Step 74 (first active material layer forming step)

On the metal foil coated with a surface of the remeltable resin composition layer 40, the active material mixture 8 is uniformly flowed from the hopper 6, and the active material mixture 8 is dried by the drying device 9 to form an active material. Material layer 31.

Step 75 (step of forming a second remeltable resin composition layer)

In the same manner as in step 72, as shown in Fig. 13, a film 42 of a remeltable resin composition is provided on the other surface of the metal foil 1, and the two are bonded by pressing the roller 41. It can be hot pressed if necessary.

Step 76 (second active material layer forming step)

Next, on the surface of the film 42 of the remeltable resin composition layer, the active material mixture 8 is uniformly flowed from the hopper 7 and dried by the drying device 10 to form the active material layer 32.

Step 77 (drying, pressurizing step)

The metal foil having the active material layers on which the active material layers 31 and 32 are formed on both surfaces is passed through a press machine 11 to be heated and pressurized. By this heating and pressurizing step, the active material layers 31, 32 will be made of a remeltable resin composition. The layers 40, 42 are evenly adhered to the surface of the metal foil. Further, by the bonding step, the heating and the pressurizing step, the metal particles of a part of the roughened metal layer 3 grown by the above surface treatment can be brought into the remeltable resin composition layer.

As shown in FIG. 6, the roughened metal particles 35 are moved away from the surface of the metal foil in the bonding step of the remeltable resin composition layer and the pressing step of the active material, and further into the remeltable resin composition layer 40. (42) to improve the electrical conductivity between the interface between the active material layer 31 (32) and the metal foil 1. Further, in the figure, 33 is an active material, and 37 is a binder and a conductive material added as necessary. The characteristics of the roughened metal particle distribution are concentrated on the metal foil side and are reduced toward the active material layer.

Step 78 (rolling step)

The pressed and dried metal foil having the active material layer is taken up by the coiler 12, and then transported to the next electrode and the battery.

Further, the above film can reduce troubles in battery assembly by, for example, using the same separator as the electrode of the lithium ion secondary battery.

Eighth embodiment

Hereinafter, a manufacturing flow chart of a metal foil having a coating layer according to an eighth embodiment of the present invention shown in FIG. 15 and a manufacturing apparatus shown in FIG. 16 will be described.

Step 81 (surface roughening treatment step)

As shown in FIG. 16, the metal foil 1 is introduced into the surface roughening treatment tank 2, and metal particles are grown on the surface of the metal foil 1 to form the roughened metal layer 3.

As shown in FIG. 15, the metal foil 1 is introduced into the surface roughening treatment tank 2 by the feeding electrode 20, and passes through the plating electrodes 22, 24, 26 disposed in the surface roughening treatment tank 2. In FIG. 13, the plating electrodes 22, 24, and 26 are disposed at three places to roughen the both surfaces of the metal foil 1, and if the roughening treatment is performed only on a single surface, the electrode 26 can be omitted, for example. The conditions of the roughening treatment and the like will be explained later.

Next, it is introduced into the water washing treatment tank 4 to perform water washing of the roughened metal layer 3.

The water-washed metal foil is further introduced into the rust-preventing treatment tank 5, and the surface of the roughened metal layer 3 is coated with a rust preventive agent. This rust-preventing treatment can be omitted if there is no concern about the oxidation of the roughened metal layer.

Step 82 (Step of forming a remeltable resin composition layer)

On both surfaces of the roughened metal foil 1, a remeltable resin composition layer 40 is provided. As the remeltable resin composition, a commercially available thermoplastic resin composition can be used. In the present embodiment, it is preferred to select a resin composition which can be attached to the active material layer provided on the resin composition layer.

As shown in Fig. 16, a film 40 of a remeltable resin composition is provided on both surfaces of the metal foil 1, and the two are bonded by a roller 41. It can be hot pressed if necessary.

Further, the film can reduce troubles in battery assembly by, for example, using the same separator as the electrode of the lithium ion secondary battery.

Step 83 (Step of producing active substance mixture)

a mixed active material, a binder, and, if necessary, a conductive carbon black or a tackifier, and a slurry, and the active material mixture 8 is supplied to the storage tank 6, 7.

When the active material layer is formed, the active material 31 is adhered to the metal foil 1 by the above-mentioned remeltable resin composition layer 40, and if necessary, for example, polybenzamine is preferably used as a binder to form a homogeneous slurry. Coating layer.

Step 84 (first active material layer forming step)

On the surface of one of the metal foils formed of the remeltable resin composition layer, the active material mixture 8 is uniformly flowed from the hopper 6 to form the active material layer 31, and the surface of the active material layer 31 is The film 13 is supplied from the film supply roller 15 to be bonded.

Step 85 (second active material layer forming step)

On the film 13 provided by the supply roller 14 of the film 13, the hopper 14 is uniformly flowed into the active material mixture 8 on the other surface of the metal foil covered with the remeltable resin composition layer. The active material mixture 8 carried by the film 13 is provided to form the active material layer 32.

Step 86 (drying, pressurizing step)

The metal foil having the active material layers on which the active material layers 31 and 32 are formed on both surfaces is passed through a press machine 11 to be heated and pressurized. By this heating and pressurizing step, the active material layers 31, 32 are uniformly adhered to the surface of the metal foil by the remeltable resin composition layers 40, 42. Further, by the bonding step, the heating and the pressurizing step, the metal particles of a part of the roughened metal layer 3 grown by the surface treatment can be brought into the remeltable resin composition layer.

Step 87 (rolling step)

Pressurized and dried metal foil with active material layer as coiler 12 is taken up and then transported to the next electrode, battery process.

In the present embodiment, the film 13 is provided on the active material layer 32. Therefore, when the coiler (for example, the spool) 12 is wound up, the active material layer 32 and the active material layer 32 do not directly contact each other, so that the active material layer is not damaged when wound up.

Further, the film can be used, for example, using the same separator as the electrode of the lithium ion secondary battery to reduce troubles in battery assembly. Further, when it is not necessary to cover the surface of the active material with a film, it may be removed after the drying step of the active material layer.

Step 88

A battery electrode was produced using the metal foil having the active material layer produced as described above.

Step 89

The battery for the above electrode is assembled to complete the production of the battery.

In the metal foil having a coating layer of the present invention, the metal foil as the active material layer of the coating layer can be used as a battery electrode in this state because the active material layer is formed on the surface of the metal foil. Therefore, the metal foil can be selected from a suitable metal as a current collector constituting the battery electrode. For example, the positive electrode of the lithium ion secondary battery may be selected from an aluminum foil, and the negative electrode may be selected from a copper foil.

In the following description, an electrolytic copper foil is used as a metal foil as an example, but the electrolytic copper foil may be replaced with a rolled copper foil.

Further, not only the electrolytic copper foil, but also the metal foil for the lithium ion secondary battery used for the same purpose as the electrolytic copper foil or the battery current collector for other purposes, the copper foil is the same as the copper foil. The electric body does not wrinkle An electrode for a lithium ion secondary battery (with active material that can be folded, does not cause breakage of the current collector, and can increase the adhesion between the active material and the current collector metal foil, and can maintain stable secondary battery characteristics for a long period of time The metal foil of the metal foil of the layer, regardless of which metal foil is selected, can be used as the metal foil having the active material layer.

In the present embodiment, in the surface roughening step, a roughened layer is formed on the surface of the metal foil of the copper foil by a scoring plating method in which a current exceeding a limit current density flows in the electrolytic cell. The roughened layer formed by the roughening treatment by the scorch plating method is dendritic, and the front end portion of the dendritic roughened layer is fragile.

In the present embodiment, the roughened layer is formed by a scoring plating method on the surface of the base metal foil having a surface roughness Rz of 0.5 to 5 μm. In the roughening treatment, particles having a growth particle diameter of 0.1 to 3 μm are preferred. Further, when the active material layer is formed on both surfaces of the base metal, the difference in roughness Rz between the front and back surfaces of the base metal foil is preferably 2.5 μm or less.

In the step of growing the active material layer on the surface of the roughened layer before the roughening layer is formed, it is preferable to use the above-mentioned cathodic electrolytic plating method to remove the ‧ dispersion The strength is set on the active material layer.

However, the metal particles grown by the surface treatment can be grown in the above preferred range by electroplating, and are not limited to the scorch plating method. Further, the surface of the metal foil is subjected to a particle-like surface roughening treatment, and the front end portion where the particulate roughening treatment layer is grown is provided in the step of providing the active material layer on the surface of the roughening treatment layer as long as it is active material The plating method in which the strength of the peeling and the dispersion can be set in the layer can be selected and used regardless of the method.

Further, in the roughening treatment by the electroplating method on both the front and back surfaces of the metal foil, it is preferred to select a metal foil having a smooth surface, and to flow a current having a limit current density or more in the electrolytic cell to form a particle diameter of 0.1. A dendritic roughening layer of ~3.5 μm, the surface roughness Rz of the roughened layer is 0.5 to 5 μm, and the difference of the surface roughness Rz between the front and back surfaces is 2.5 μm or less.

Further, when the active material layer is formed on both the front and back surfaces, if the metal foil is electrolytic copper, the crystal structure of the cross section is preferably fine granular crystal. Since the crystal structure of the copper foil is a granular crystal, the difference in roughness between the front and back surfaces can be made small, because the difference in roughness Rz value after the roughened particles are applied is reduced. When the copper foil has a columnar crystal structure, the difference in the roughness of the front and back surfaces becomes large, and it is difficult to eliminate the difference even after the roughening treatment.

The metal foil for a lithium ion secondary battery electrode of the present invention is used in a electrolytic cell for causing a current having a current of a limit current or more to flow through a scorching plating (hereinafter referred to as a scorch plating), and a grain is formed on the front and back surfaces of the base metal foil. The layer of roughened particles having a diameter of 0.1 to 3 μm has a surface roughness Rz of 0.5 to 5 μm on the individual surfaces and a roughness Rz of 2.5 μm or less on the front and back surfaces.

When the metal foil is, for example, an electrolytic copper foil, the roughening particle treatment on the surface of the base copper foil not only improves the adhesion to the active material, but also can be roughened by the volume change of the expansion and contraction inside the battery. The resulting void space is used to soothe and absorb the stress.

When the metal foil is an electrolytic copper foil, the material forming the roughening treatment layer is preferably Cu roughened particles, or Cu as a main component, and contains Fe, Ni, Cr, W, Mo, V, or a plurality of species. Particles. By forming a roughened layer by roughening particles composed of Cu or a copper alloy containing Cu as a main component, the adhesion between the roughened particles and the base copper foil can be improved, or by appropriately controlling the charring The current density (limited current density) of the plating is used to control the particle diameter of the roughened particles, and the surface roughness Rz value can be adjusted more easily and arbitrarily.

The copper foil as the metal foil may be an electrolytic copper foil or a rolled copper foil, and preferably has a surface roughness of 0.8 to 2.0 μm, and the crystal grain boundary structure at room temperature is a granular crystal having a particle diameter of 5 μm or less. In terms of physical properties, the tensile strength (TS) is 300 MPa or more at normal temperature, and the elongation (E) is 3.5% or more, and the tensile strength after 150 ° C for 15 hours can be maintained at 250 MPa or more.

Generally, the larger the crystal grain size, the lower the tensile strength (T.S) of the metal foil and the higher the elongation (E). When ruthenium, osmium, tin, or the like is used as the negative electrode active material and the strength (TS) of the current collector (metal foil) is low, the expansion and contraction of the battery cannot be absorbed regardless of the roughening treatment. Moreover, the metal foil is prone to cracking and fracture. In order to avoid this, the tensile strength is preferably 300 MPa or more, the elongation is preferably 3.5% or more, and the crystal structure particle diameter is preferably 5 μm or less.

Further, there is a drying step in the process of the negative electrode current collector for a lithium ion secondary battery, and when the drying is incomplete, deterioration of battery characteristics is well known. The drying conditions at this time are generally 5 to 20 small at 100 to 200 ° C. Time. At this time, when the current collector (metal foil) is plastically deformed or softened, problems such as cracking of the metal foil during charging and discharging occur due to the above reasons, and therefore the strength (hardness) of the metal foil becomes important after the drying step. Physical factors.

Among the drying step conditions in which the metal foil is used, the most mechanical property changes are copper foil.

In the development of the electrolytic copper foil to the present, in the technique of suppressing recrystallization (plastic deformation) during heating of the electrolytic copper foil, it is preferable to use a foil forming method in which the concentration of the additive composition of the electrolytic solution is set to be different when the electrolytic copper foil is pressed. MPS (sodium 3-mercapto-1-propane sulfonate) is 3 to 10 ppm, HEC (hydroxyethyl cellulose ‧ polymeric polysaccharides) is 15 to 20 ppm, and animal glue is 30 to 70 ppm.

The surface area after the treatment of the roughened particles is preferably 2.5 to 5 times. The surface area ratio is measured using a VK-8500 manufactured by KEYENCE Corporation to measure the area of 2500 μm ² (50 μm x 50 μm) on the surface of the metal foil. The base metal foil (before roughening treatment) and roughening treatment are used. The area is expressed in proportion to the ratio obtained. That is, when the surface area ratio is 1, the surface of the electrode before and after the roughening treatment is not changed, and if the area after the roughening treatment is 5000 μm ² , the surface area is doubled.

The tensile strength (T.S) and the elongation (E) of the present invention are values obtained by measurement according to the method specified in Japanese Industrial Standards (JISK 6251).

Further, the surface roughness Rz is a value obtained by measuring a ten-point average roughness and an arithmetic surface roughness defined by Japanese Industrial Standards (JISB 0601-1994) using a general surface roughness meter.

Roughening the surface of the metal foil by scorch plating 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 scoring method is a plating method in which an electric current of a limit current density or more is passed through an electrolytic cell, and is applied to a roughening treatment method for imparting a uniform concave-convex pattern to a smooth base metal foil surface. By this scoring plating method, the front and back surfaces of the metal foil can be roughened.

For the method of roughening the surface of the metal foil, in particular, the surface of the electrolytic copper foil by the scoring method, for example, the method disclosed in Patent Document 5 (Japanese Patent Laid-Open No. 53-39376) can be used. Preferably, a method generally used for printing a copper foil for a circuit is used.

However, in the above-mentioned Patent Document 5, after the formation of the powdery copper plating layer by "scorch plating", the powdery copper plating layer is subjected to "capsule plating" without damaging the uneven shape, that is, the essence A smooth plating layer is formed to form a smooth seaweed ribbon-like copper roughening layer in which the powdery copper does not fall off (without falling off the powder).

The reason why the present invention is treated only by scorch plating is as follows.

When the surface of the base metal foil is subjected to scoring plating, the dendritic particles forming dendrites are uniformly attached to the front and back surfaces of the metal foil. The roughened particles which are dendritic are attached to the front and back surfaces of the metal foil in a fragile state in which the front end is easily broken and peeled off.

In the present invention, the active material layer is applied over the dendritic roughened particle layer adhered in the above-described fragile state. Coating and drying the active material composition having the active material and the binder on the remeltable resin roughened copper foil, followed by a pressing step, and the adhered resin is again formed For liquids, the dendritic roughened particles will be damaged when the active material is applied, or when it is expanded and contracted during drying, or when it is pressed, and the damaged particles will be dispersed in the active material composition, and the mixed particles become active. Part of the composition of matter.

Further, in the production step of the active material layer, the scorching of the plating layer does not cause hindrance.

After the application, drying, heating and pressurization steps of the active composition, the unnecessary solvent in the slurry-form active material is volatilized to form a consolidated active material. At this time, the dendritic particles will fall off, and the roughened particles which are detached will be mixed into the active material layer, and the portion where the dendritic active material does not fall off will constitute the roughness (concavity and convexity) of the surface of the copper foil on the roughened surface. The active material layer is closely adhered to the front and back surfaces of the copper foil by the adhesive. Therefore, by the roughening treatment by the scorch plating, the front end portion which is stretched into a dendritic shape is brought into the active material layer, and the active material layer is formed in a state where the copper particles in the active material are free. The basic part forms a roughened shape of the surface of the copper foil along the shape of the active material, which not only enhances the adhesion between the active material and the copper foil, but also has less internal residual stress than the conventional roughened copper foil. The rate is increased, and an electrode for generating a battery for heat generation is formed. Further, in the coating, drying, heating, and press-bonding processes of the active material composition, the roughened particles of the base portion are sintered and adhered to the surface of the copper foil due to exposure to a high temperature of 300 °C.

In addition to the above-described scorching plating, as disclosed in Japanese Laid-Open Patent Publication No. 2007-270184, the roughening treatment tank 2 can be replaced with a conductive aqueous solution containing a polymer dispersion medium to be untreated. The treatment of depositing copper nanoparticles on the surface of the copper foil. Since the copper particles are small, and thereafter, when used as a battery negative electrode, the copper nanoparticles can be brought into contact with the active material without a gap, and the effect of improving the electrical conductivity with the negative electrode current collector can be obtained.

In the roughening treatment step of the present embodiment, unlike conventionally, capsule plating is not performed after the scoring plating. Since the capsule plating is not performed, the roughened particles are not fixed to the base metal foil, and the active material forms roughened particles and moves by heating under pressure (pressing), and the roughened particles will follow along. The shape of the active material is moved in a state in which it is partially mixed into the active material layer, and the largest contact area is formed between the roughened particles and the active material. When the copper foil which is subjected to capsule electroplating after the above-mentioned scorching electroplating is used, since the roughened particles are fixed to the base metal foil, even if the roughened particles are mixed into the active material under the pressing pressure, the roughened particles do not move, and the roughened particles will not move. The residual stress is caused to occur between the active material and the base metal foil, and when it is used as the negative electrode of the battery, the base metal foil is broken.

In addition to the conventional black lead, the active material of the present invention may also be an active material which can absorb and release lithium and perform alloying by lithium alloying. The active material may be, for example, ruthenium, osmium, tin, lead, zinc, manganese, sodium, aluminum, potassium, indium or the like. Among them, ruthenium and tin have a high theoretical capacity and are easy to use because they are used as a negative electrode active material. Therefore, both of them are preferable, and they have been gradually used in recent years.

In addition to the black lead, the negative electrode active material layer of the lithium ion secondary battery is preferably an active material layer containing ruthenium or tin as a main component, and more preferably a thin layer mainly composed of ruthenium.

Further, the active material layer is preferably an amorphous layer or a microcrystalline layer, and when an anthracene is selected, an amorphous layer or a microcrystalline layer is preferred.

In the present embodiment, it is revealed that the thickness of the current collector is small, and the design of the secondary battery is preferably light and light. Therefore, the metal foil is preferably selected from a copper foil as a negative electrode current collector, and aluminum is selected as a positive electrode current collector. The active material layer can be formed by coating and stacking on a single surface or both surfaces of the current collector. When the active material layer is formed on both the front and back sides of the current collector, it is preferable that the surface roughness Rz of both surfaces of the current collector is in the range of 0.5 to 5 μm, and the Rz value of the front and back surfaces is also different from 2.5 μm. the following.

The thickness of the current collector (metal foil) is preferably 8 μm for the thinner and 20 μm for the thicker one. This is because the strength of the metal foil (as a current collector) cannot be maintained below 8 μm, and cracks and fractures are likely to occur during expansion and contraction of the active material. On the other hand, when it exceeds 20 μm, although the battery characteristics can be satisfied, the battery itself becomes large and becomes heavy, so it is preferably set to about 20 μm.

The Rz values of the two surfaces are set in the range of 0.5 to 5 μm. This is because if the Rz value is lower than the lower limit value, the adhesion to the anchoring effect between the active material layers is lowered. When the upper limit value is exceeded, the relatively active material does not uniformly enter the valley in the roughened unevenness. The recess is such that the adhesion between the current collector and the active material layer is insufficient, so it is preferable not to exceed this upper limit.

When the difference between the front and back of the surface roughness is too large, the thickness of the active material on the two surfaces in the coating process of the active material will be different, resulting in problems in the electrode characteristics of the battery. Therefore, the difference in the roughness Rz value between the front and back surfaces is set to 2.5 μm or less. That is, when the difference between the Rz values of the front and back surfaces is If it is different from 2.5 μm or more, the thickness of the active material on both surfaces in the coating process of the active material will be different, and the characteristics of the battery electrode cannot be sufficiently displayed.

The lithium ion secondary battery of the present invention includes a negative electrode which is coated and laminated with an active material layer of an active material for a lithium ion secondary battery mainly composed of black lead, bismuth or tin, and can be used for absorption and discharge. A positive electrode of a lithium substance, a nonaqueous electrolyte, and a separator.

The nonaqueous 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 nonaqueous electrolyte is not particularly limited as long as it is a solvent usable for a lithium ion secondary battery. For example, it is a cyclic carbonate such as ethylene carbonate, propylene carbonate, butylene carbonate or vinylene carbonate, a chain carbonate such as dimethyl carbonate, diethyl carbonate or ethyl methyl carbonate, and the like. A mixed solvent of a cyclic carbonate and a chain carbonate is used. Further, an ether solvent such as a cyclic carbonate and 1,2-dimethoxyethane or 1,2-diethoxyethane, γ-butyrolactone, cyclobutyl hydrazine, methyl acetate or the like may be used. A mixed solvent of a chain ester or the like.

The solute of the nonaqueous electrolyte is not particularly limited as long as it is a solute usable for a lithium ion secondary battery, and may be, 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 , Li ₂ B ₁₀ Cl ₁₀ , Li ₂ B ₁₂ Cl ₁₂ and the like.

Further, the non-aqueous electrolyte can be used as a colloidal polymer electrolyte for immersing an electrolyte in a polymer electrolyte such as polyethylene oxide, polyacrylonitrile or polyvinylidene chloride resin, and an inorganic solid electrolyte such as LiI or Li ₃ N.

The electrolyte of the lithium ion secondary battery of the present invention is only required to be charged and discharged in the battery Any electrolyte can be used without limitation in the range of electricity or when the voltage at the time of storage is not decomposed.

Further, the positive electrode active material used for the positive electrode may be, for example, a lithium-containing transition metal oxide such as LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiMnO ₂ , LiCo _0.5 Ni _0.5 O ₂ , LiNi _0.7 Co _0.2 Mn _0.1 O ₂ or the like. And a metal oxide or the like which does not contain lithium, such as MnO ₂ , but any substance which can absorb and release lithium ions in the battery can be used without limitation.

According to the present invention, when the active material mixture is applied, the conductive metal fine particles (the roughened layer to be peeled off) are mixed into the active material layer by the drying, the pressurization process, or the like, and are appropriately dispersed in the active material layer. The conductivity of the active material layer is increased, and wrinkles, cracks, and fractures of the negative electrode current collector during charge and discharge are suppressed, and the energy density per unit volume of the lithium ion secondary battery is improved, thereby providing long-term maintenance. Lithium ion secondary battery with stable performance.

In the embodiment shown in Figs. 11 and 15, when the metal foil having the active material layer is wound up, a film (separator) may be interposed in order to protect the surface of the active material layer which is overlapped.

As described above, since the film is disposed on one surface, when the metal foil having the active material layer is curled, the active material layers can be prevented from contacting each other in advance, and sometimes problems due to damage.

Further, when the metal foil having the active material layer is used as the electrode of the secondary battery, if the film is formed of the same material as the separator for the battery electrode, the separator and the electrode can be shared without removing .

In addition, in addition to the separator as an electrode, the film is preferably used Molded paper.

The battery separator is an important material for separating the positive electrode from the negative electrode and maintaining the electrolyte to ensure ionic conductivity between the positive electrode and the negative electrode. The type of the separator varies depending on the battery. In the lithium ion battery, a microporous membrane made of polyethylene (ultrahigh molecular weight PE) and polypropylene (PP) is used, which has a single layer type and a pair of PE/PP. Layer structure, type of three-layer structure of PP/PE/PP. In view of the characteristics of the glass transition temperature (TG) of these resins, the drying temperature or the conditions of heating and pressurization must be set to a temperature lower than the glass transition temperature (TG) of the resin. In the present embodiment, polyethylene (ultrahigh molecular weight PE) is used.

Example

In the following, an embodiment of the present invention will be described in detail with reference to an embodiment of the present invention. However, the present invention is not limited by the following examples, and may be within the scope of the spirit of the present invention. For appropriate changes, for example, a metal foil other than copper foil or the like is used.

[Examples 1 to 3 and Comparative Example 1]

[Manufacture of electrolytic copper foil]

Examples 1, 4 and Comparative Example 1

In the present embodiment, the metal foil is made of copper foil.

Electrolytic mother liquor for foil production

In a copper sulfate electrolytic cell having a metal copper of 70 to 130 g/l and a sulfuric acid of 80 to 140 g/l, MPS, HEC having the composition shown in Table 1 and chloride ions as an additive were added to prepare an electrolytic mother liquid for foil formation. In the table, MPS is sodium 3-mercapto-1-propane sulfonate, HEC (polymer polysaccharide) hydroxyethylcellulose Vitamin, a gel refers to a low molecular weight gel with a molecular weight of 3,000.

Here, the chloride ion concentration is adjusted to 30 ppm, but the chloride ion concentration can be appropriately changed depending on the electrolysis conditions, and is not limited to this concentration.

Foil

Using the prepared electrolytic mother liquid, a titanium electrode was coated with a noble metal oxide at the anode, a titanium cylinder was used for the cathode, and electrolytic copper having a thickness of 10 μm was produced by the electrolytic conditions (current density, liquid temperature) shown in Table 1. Foil. The surface roughness Rz and mechanical properties of the foil-formed electrolytic copper foil are shown in Table 2.

Sodium 3-hydrogenthio-1-propane sulfonate

Hydroxyethyl cellulose

Animal gum with a molecular weight of about 3,000

Further, each of the measured values shown in Table 2 was measured by the following method.

[Measurement of Thickness, Tensile Strength (T.S), Elongation (E) of Foil]

The measured values were measured by a micrometer, and the tensile strength (T.S.) and elongation (E) were measured by a tensile tester (Model 1122 manufactured by Instron Co., Ltd.). The surface roughness Rz is a value measured by a probe type surface roughness meter (SE-3C type manufactured by Otaru Laboratory).

[Roughening of the surface of metal foil]

The positive and negative surfaces of the 10 μm electrolytic copper foil produced under the above-described foil-forming conditions were subjected to scorch plating of copper under the following conditions using the apparatus shown in FIG.

That is, in the first embodiment, the electric heating shaft 20 shown in FIG. 8 is used as an anode, and the electric current electrode 20 disposed in the processing tank 3 is used as a cathode. The electrolytic copper foil of the above-mentioned foil is subjected to the following scoring conditions. The surface treatment is followed by water washing in the treatment tank 4. Although only one tank is shown in Fig. 8 in the treatment tank 4 for water washing, the treatment tank for water washing can be added as necessary. Next, if necessary, in the subsequent drying process, in the case where the copper foil does not change color, the rust-preventing treatment tank 5 may be added to perform rust-preventing treatment, and may be slightly dried before the slurry coating.

The property values assigned to the roughened particles are listed in Table 3.

The property values after the roughened particles imparted by the scoring plating are listed in Table 3.

Surface roughening treatment (scorch plating) conditions: metallic copper 22.5~24.0 g/l

Sulfuric acid 90~120 g/l

Mo added metal 0.35 g/l

Slot temperature 18~30°C

Current density 25~35 A/dm ²

Processing time 2.5~7.5 seconds

Other representative addition metals are, for example, Fe, Ni, Cr, W, V, and the like. Further, a plurality of the above metals may be selected and added.

In the fourth embodiment, the power supply shaft 20 shown in Fig. 8 was used as an anode, and the electric current electrode 20 was used as a cathode, and the roughening treatment was carried out under the following conditions.

Surface roughening treatment conditions

Generally copper electrolyte (copper sulfate 40~250 g/l, sulfuric acid 30~210 g/l, hydrochloric acid 10~800 ppm, additives such as brightener, prepared by the manufacturer's specified amount), electrolyte temperature Maintain 18~32 °C and set the current density of 1A/dm ² .

When the current density is lower than 1 A/dm ² , the amount of copper plating will be too small, and almost no copper particles can be precipitated. Therefore, in Example 4, it was carried out at 8 A/dm ² . When the current density is increased, the amount of precipitated copper particles is increased, and if necessary, the amount of precipitation of copper particles can be controlled by controlling the current density.

Example 2, 3

In Examples 2 and 3, a rolled copper foil was used, and the copper foil was subjected to the same surface treatment as in Example 1.

Example 2 and Comparative Example 2

In the present embodiment, a low-roughness rolled copper foil (copper for contacts) made by Nippon Foil Co., Ltd. was used.

Example 3

In the present embodiment, a tin-containing (0.15 wt%) copper alloy foil (C14410) made by Nippon Foil Co., Ltd. was used.

Example 4

In the embodiment 4, the same electrolytic copper foil as in the first embodiment was used, and the electric axis 20 was used as the anode and the electric electrode 20 was used as the cathode. The surface roughening treatment conditions similar to those in the example 1 were carried out to form copper particles on the surface of the foil (0.1). Μm~3.5 μm), followed by water washing in the treatment tank 4. Although the treatment tank for washing is shown in Fig. 2, only one tank is shown, but if necessary, the treatment tank for water washing can be added. Next, if necessary, in the subsequent drying process, in the case where the copper foil does not change color, the rust-preventing treatment tank 5 may be added to perform rust-preventing treatment, and may be slightly dried before the slurry coating.

The property values assigned by the roughened particles are listed in Table 3.

[Measurement of Rz value, surface area, crystal grain size]

The Rz value of the front and back of the copper foil was measured by a SE-3C type measuring apparatus manufactured by Otaru Laboratory, and the surface area of the copper foil after the roughening particle treatment was measured by VK-8500 manufactured by KEYENCE. The particle size profile of the crystal structure was judged by an SEM image taken by an eye visual scanning electron microscope.

Active material granulation

The active material may be cerium (SiO) mixed with cerium (SiO), acetylene black, PVDF (polyvinylidene chloride resin), NMP (1-methyl-2-pyrrolidone) to form a slurry.

Formation of active material layer

Each of the copper foils of the examples and the comparative examples is used as a current collector, and the active material formed in the slurry form is applied onto the current collector, and dried by heating and pressure-bonding to form a ruthenium-based buildup layer ( The active material layer) is used to produce a copper foil having an active material.

In order to facilitate the application by the curtain type flat coater, the active material mixture is a volatile solvent to adjust to a suitable slurry viscosity. Further, although a method of applying an active material mixture by a curtain type flat coater is used here, it is also applicable to a coating method using other rolls.

The method of manufacturing a thin metal having an active material layer is carried out by adding an active material or a binder as a main component, and if necessary, a viscosity-increasing material or a conductive auxiliary agent may be added to adjust the viscosity. The active material mixture formed by the kneading is applied to the surface of the metal foil on which the metal particles are deposited, and after drying, the metal particles are strongly contacted with the active material by heat-pressing, and a part of the metal particles as the conductive auxiliary agent will be dispersed. On the surface of the active material layer, the contact resistance between the active material layer and the current collector (metal foil) can be lowered. In addition, since a part of the roughening treatment layer as a conductive auxiliary agent is disposed from the surface of the metal foil toward the inside of the active material layer, and since the conductivity has a tendency to decrease from the surface of the metal foil toward the inside of the active material layer, contact with the metal foil The area is larger than the copper foil which is usually applied by capsule plating, and the contact area is maximized. Can contribute to the cycle characteristics of the battery.

The installation and evaluation of the anode current collector were carried out under the following conditions.

[Production of Electrolysis Cell]

The produced negative electrode current collector was used as an electrode, and a three-electrode electrolytic cell was fabricated in an argon-filled glove box. The electrolytic cell is composed of an anti-electrode (positive electrode), a working electrode (negative electrode), and a reference electrode in an electrolytic solution filled in a glass container.

The electrolytic solution was obtained by dissolving 1 mol/liter of LiPF _{6 with respect} to a solvent in which a ratio of ethylene carbonate to diethyl carbonate was 3:7 by volume. The counter electrode and the reference electrode system utilize lithium metal.

Evaluation of charge and discharge cycle characteristics

The electrolytic cell prepared by charging the working electrode (negative electrode) at a potential of 0 V (vsLi/Li ⁺ ) at a constant current of 4 mA at 25 ° C, and then applying a current of 4 mA to the working electrode (negative electrode) The potential was increased to a potential of 2 V (vsLi/Li ⁺ ), and the discharge capacity retention rate was evaluated after 100 cycles of charge and discharge efficiency.

The results of the assessment are listed in Table 3.

In addition, the presence or absence of cracking/fracture of the copper foil after repeated charge and discharge for 300 cycles was confirmed, and the results are also shown in Table 3.

As shown in Table 3, in the current collector of Example 1, the Rz value of the base copper foil was different from the standard value, and the roughened particle diameter and surface area after the roughened particles were supplied were also within the standard values.

The evaluation of the charge-discharge cycle characteristics of the electrolytic cell battery fabricated by using the copper foil of Example 1 as a current collector completely conforms to the standard and is repeated. No cracking/fracture was observed in the current collector after charging and discharging for 300 cycles.

The base copper foil of Example 2 and Example 3 was subjected to the same roughening treatment as the electrolytic copper foil of the above-described Example 1 by using a rolled copper foil, and the roughened copper foil was used as the current collector, and the examples were as follows. The same is done for the assembly of the battery and the evaluation of its battery characteristics. The results are shown in Table 3 together with Example 1.

On the other hand, in Comparative Example 1, the untreated copper foil was used in the same manner as in Example 1, but the roughness Rz value of both surfaces after the roughening treatment was increased, so that the discharge capacity retention rate after 100 cycles of charge and discharge efficiency could not be obtained. Meet the standard value.

Further, in Comparative Example 1, a phenomenon of cracking/fracture was observed in the current collector after repeated charge and discharge for 300 cycles.

According to the present invention, not only the energy density per unit volume of the lithium ion secondary battery but also the problem of deformation such as wrinkles and cracks of the current collector during charge and discharge can be suppressed, and even if the charge and discharge cycle is repeated, It is also possible to provide a lithium ion secondary battery which has a high life without causing a decrease in capacity and which can be miniaturized.

1‧‧‧metal foil

2‧‧‧Surface roughening treatment tank

3‧‧‧Roughened metal layer

4‧‧‧Washing treatment tank

5‧‧‧Anti-rust treatment tank

6‧‧‧ hopper

7‧‧‧ hopper

8‧‧‧Active substance mixture

9‧‧‧Drying device

10‧‧‧Drying device

11‧‧‧Compression machine

12‧‧‧Winding machine

13‧‧‧film

14‧‧‧ film supply device

15‧‧‧film supply device

16‧‧‧Fitting device

20‧‧‧Power electrode

22, 24, 26‧‧‧ electrodes

31, 32‧‧‧ active material layer

33‧‧‧Active substances

35‧‧‧Metal particles

37‧‧‧Binder (conductive material)

Fig. 1 is a flow chart showing the manufacture of a metal foil having a coating layer according to the first embodiment.

Fig. 2 is a cross-sectional view showing a metal foil having a coating layer according to the first embodiment.

Fig. 3 is a flow chart showing the manufacture of a metal foil having a coating layer according to the second embodiment.

Fig. 4 is a cross-sectional view showing a metal foil having a coating layer according to a second embodiment.

Fig. 5 is a flow chart showing the manufacture of a metal foil having a coating layer according to a third embodiment.

Fig. 6 is a cross-sectional view showing a metal foil having a coating layer according to a third embodiment.

Fig. 7 is a flow chart showing the manufacture of a metal foil having a coating layer according to a fourth embodiment.

Fig. 8 is a cross-sectional view showing a metal foil having a coating layer according to a fourth embodiment.

Fig. 9 is a flow chart showing the manufacture of a metal foil having a coating layer according to a fifth embodiment.

Fig. 10 is a view showing a manufacturing apparatus of a metal foil having a coating layer according to a fifth embodiment.

Fig. 11 is a view showing a manufacturing apparatus of a metal foil having a coating layer according to a sixth embodiment.

Fig. 12 is a flow chart showing the manufacture of a metal foil having a coating layer according to a sixth embodiment.

Fig. 13 is a flow chart showing the manufacture of a metal foil having a coating layer according to the seventh embodiment.

Fig. 14 is an explanatory view showing a manufacturing apparatus of a metal foil having a coating layer according to a seventh embodiment.

Fig. 15 is a flow chart showing the manufacture of a metal foil having a coating layer according to the eighth embodiment.

Fig. 16 is an explanatory view showing a manufacturing apparatus of a metal foil having a coating layer according to an eighth embodiment.

10‧‧‧metal foil

11‧‧‧Free metal ions

12‧‧‧ Coating resin

Claims (34)

A metal foil having a coating layer on which a coating layer is disposed on at least one surface 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 disposed above the resin composition layer. A metal foil having a coating layer on which at least one surface of a metal foil is disposed, and a coating layer is disposed on the roughened layer, wherein the coating layer contains free metal particles. The metal foil having a coating layer according to claim 5, wherein the free metal particles contained in the coating layer are metal particles liberated from the roughening treatment layer. A metal foil having a coating layer according to the invention of claim 5, wherein the coating layer is a remeltable resin composition. A metal foil having a coating layer according to claim 5 or 6, wherein the coating layer is an active material layer. The metal foil having a coating layer according to claim 5, wherein the coating layer is a remeltable resin composition layer, and an active material layer is disposed above the resin composition layer. The metal foil having 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. The metal foil having a coating layer according to any one of claims 1 to 9, wherein the free metal particles have a particle diameter of 0.05 μm to 3.5 μm. The metal foil with a coating layer according to any one of claims 5 to 9, wherein the roughening treatment layer comprises at least copper, nickel, manganese, iron, chromium, tungsten, molybdenum, vanadium, and indium. A roughening treatment layer of more than one metal. A metal foil having a coating layer on which a film or a release paper is disposed on a surface of at least the outermost layer of the metal foil having a coating layer according to any one of claims 1 to 9. An electrode for a secondary battery, wherein an active material layer is disposed on at least one surface of the 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 disposed on at least one surface of a metal foil, and an active material layer is disposed on the resin composition layer. An electrode for a secondary battery, wherein a roughened layer is disposed on at least one surface of the metal foil, and an active material layer is disposed on the roughened layer, and the active material layer contains free metal particles. The electrode for a secondary battery according to claim 16, wherein the free metal particles contained in the active material layer are metal particles liberated from the roughened layer. An electrode for a secondary battery on at least one surface of a metal foil A roughening treatment layer is disposed, and a remeltable resin composition layer containing free metal particles is disposed on the roughening treatment layer, and an active material layer is disposed on the resin composition layer. The electrode for a secondary battery according to claim 16, wherein the free metal particles contained in the remeltable resin composition layer are metal particles liberated from the roughened layer. The electrode for a secondary battery according to any one of claims 14 to 17, wherein the metal foil is an electrolytic copper foil or a rolled copper foil. The electrode for a secondary battery according to any one of claims 14 to 17, wherein the free metal particles have a particle diameter of 0.05 μm to 3.5 μm. The electrode for a secondary battery according to any one of claims 14 to 17, wherein the roughening treatment layer contains at least at least copper, nickel, manganese, iron, chromium, tungsten, molybdenum, vanadium, and indium. One or more metal plating baths are subjected to a roughened treatment layer formed by the treatment. An electrode for a secondary battery, wherein a film or a release paper is disposed on a surface of at least the outermost layer of the electrode for a secondary battery according to any one of claims 14 to 18. The electrode for a secondary battery according to claim 21, wherein the film is a separator for a battery. A method for producing a metal foil having a coating layer, wherein a coating layer is disposed on at least one surface of the metal foil, wherein the coating layer includes a metal foil having a coating layer of free metal particles, and the surface of the metal foil is coated with a plating bath Passing the limit current density a current is applied to form a roughened layer having a particle diameter of 0.1 μm to 3.5 μm; a coating layer is formed on the roughening layer; and a part of the roughened particles are mixed in the coating layer to serve as a free metal particle. The method for producing a metal foil having a coating layer according to claim 23, wherein the coating layer is a remeltable resin composition layer. The method for producing a metal foil having a coating layer according to claim 23, wherein the coating layer is an active material layer. The method for producing a metal foil having a coating layer according to claim 23, wherein the coating layer is a remeltable resin composition layer, and an active material layer is disposed on the resin composition layer. A method for producing a metal foil having a coating layer, wherein a coating layer is disposed on at least one surface of the metal foil, wherein the coating layer includes a metal foil having a coating layer of free metal particles, and the surface of the metal foil is coated with a plating bath Passing a current above the limiting current density to form a roughened layer having a particle diameter of 0.1 μm to 3.5 μm; on the roughening layer, an active material, a binder, and a viscosity-increasing layer may be added to the coating. a mixture of active materials mixed with a slurry or a slurry to form an active material layer; and drying and pressurizing the metal foil on which the active material layer is formed to bring the metal-treated particles into the active material layer In the above, the conductive material layer contains the roughened particles as the free metal particles. A method for producing a metal foil having a coating layer, wherein a coating layer is disposed on at least one surface of a metal foil, wherein the coating layer includes a metal foil having a coating layer of free metal particles, and a surface of the metal foil is coated with a plating bath a roughening treatment layer having a particle diameter of 0.1 μm to 3.5 μm is formed by a current exceeding a limit current density; a remeltable resin composition layer is formed on the roughening treatment layer; and the resin composition layer is formed on the resin composition layer And an active material mixture in which an active material, a binder, a tackifier, a slurry, or the like may be added to the coating to form an active material layer; and the resin composition layer is formed, The metal foil of the active material layer is dried and pressurized to bring the roughened particles into the resin composition layer to form free metal particles. An electrode for a secondary battery, which is a metal foil produced by the method for producing a metal foil having a coating layer as described in claims 23 to 28. A method for manufacturing an electrode for a secondary battery, comprising: a surface roughening treatment step of forming a surface having a particle diameter of 0.1 μm to 3.5 μm by using a plating bath and a current exceeding a limiting current density on a surface of the metal foil; a treatment layer; an active material granulation step, adding an active material, a binder, and if necessary, adding a tackifier, and a slurry, etc.; mixing; a first active material layer forming step on one surface of the roughening treatment layer Upper, applying the active substance mixture produced in the above-mentioned active material granulation step; a second active material layer forming step of laminating the active material mixture on the film and laminating on the other surface of the metal foil; and drying and pressurizing the step, having the first step and the second step formed The metal foil of the active material layer is dried and pressurized to bring the roughened particles into the active material layer to serve as a conductive auxiliary agent, and the roughened particles are contained as free metal particles in the active material layer. in. A method for manufacturing an electrode for a secondary battery, comprising: a surface roughening treatment step of forming a roughening of a particle diameter of 0.1 μm to 3.5 μm by using a plating bath and a current exceeding a limiting current density on a surface of the metal foil a treatment layer forming step of forming a remeltable resin composition layer on the roughening treatment layer; an active material granulation step, adding an active material, a binder, and if necessary, adding a tackifier, and a slurry or the like, which is mixed; a first active material layer forming step, coated on the surface of one of the resin composition layers, coated with the active material mixture produced in the active material granulation step; and a second active material layer a forming step of laminating the active material mixture on the film and laminating on the other surface of the resin composition layer; and drying and pressurizing the pair to have the active material formed in the first and second steps The metal foil of the layer is dried and pressurized to bring the roughened particles into the active material layer to serve as a conductive auxiliary agent, and the roughened particles will be used as Free metal particles, containing the active substance In the layer. A lithium ion secondary battery using the metal foil according to any one of claims 1 to 13 or the metal produced by the manufacturing method according to any one of claims 23 to 28 A foil, or an electrode for a secondary battery according to any one of claims 14 to 22, or an electrode produced by the production method according to any one of claims 30 to 31.