KR20110097410A - Multilayer metal foil for lithium-battery and producing method thereof - Google Patents

Abstract

The present invention relates to a metal thin film used as a lithium battery material. According to the present invention a core layer made of a metal other than copper (Cu); A multi-layer metal thin film for a lithium battery is provided, including: a first copper layer formed on one surface of the core layer; and a second copper layer formed on the other surface of the core layer.

Description

Multi-layered metal thin film for lithium battery and manufacturing method thereof {MULTILAYER METAL FOIL FOR LITHIUM-BATTERY AND PRODUCING METHOD THEREOF}

The present invention relates to a metal thin film used as a material for lithium batteries, and more particularly, to a multilayer metal thin film for lithium batteries having a structure capable of reducing materials and improving physical properties and a method of manufacturing the same.

Lithium secondary battery has many advantages such as high energy density, high operating voltage and excellent storage and lifespan characteristics compared to other secondary batteries, which can be used for personal computers, camcorders, portable phones, portable CD players, PDAs, etc. Widely used in portable electronic devices.

In general, a lithium secondary battery includes a positive electrode and a negative electrode disposed with an electrolyte interposed therebetween, a positive electrode active material and a negative electrode active material included in the positive electrode and the negative electrode, and a positive electrode current collector and a negative electrode current collector in contact with the positive electrode active material and the negative electrode active material, respectively. It has a structure provided with.

Electrolytic copper foil is mainly used as a metal thin film used as a material of a negative electrode current collector in a lithium secondary battery, and the electrolytic copper foil is coated with an active material of a carbon-based slurry. Typically, the electrolytic copper foil is manufactured through a process for producing a raw foil by electroplating and a post-treatment process for imparting peel strength to the raw foil. In the electroplating process, the surface of the electrolytic copper foil has a relatively low roughness to form a shiny Shiny side, and on the other side, a so-called mountain structure has a relatively high roughness and a matt surface that is not glossy. Side is formed. In addition, the electrolytic copper foil undergoes a surface treatment of forming a copper nodule cluster on a mat surface in a post-treatment process to impart physical and chemical properties suitable as a current collector.

However, since the copper foil of the electrolytic copper foil is composed of a single copper layer 10 as shown in FIG. 1, a large amount of copper is required, and thus, a lot of material costs become obstacles to lowering the manufacturing cost of the lithium battery material. have.

On the other hand, the lithium secondary battery exhibits a property in which adhesion between the copper foil and the active material is greatly changed depending on the state of the copper foil used as the current collector. That is, when the surface of the copper foil is smooth and the adhesion is not good, there is a problem that the active material is detached from the surface of the copper foil during battery assembly work or during battery operation, resulting in a decrease in battery capacity or corrosion of the negative electrode.

In particular, the current collector copper foil is in contact with an active material such as a carbon-based slurry, and thus should be given an appropriate adhesion force, and has a surface property to prevent defects that concentrate charge and discharge currents at specific points. It is important.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and an object of the present invention is to provide a multilayer metal thin film for a lithium battery having a laminated structure capable of reducing copper material and improving physical properties of a thin film and a method of manufacturing the same.

Another object of the present invention is to provide a multilayer metal thin film for lithium batteries having a structure capable of preventing corrosion of electrodes and desorption of active materials, and a method of manufacturing the same.

The present invention to achieve the above object is a core layer made of a metal other than copper (Cu); It provides a multi-layer metal thin film for a lithium battery comprising a first copper layer formed on one surface of the core layer; and a second copper layer formed on the other surface of the core layer.

The core layer may be made of any one selected from aluminum (Al), nickel (Ni), manganese (Mn), zinc (Zn), tin (Sn), and iron (Fe), or two or more alloys.

It is preferable that the surface roughness Rz of at least one of both surfaces of the said core layer is 0.5-3.0 micrometers.

It is preferable that the thickness ratio of the said 1st copper layer or the said 2nd copper layer with respect to the metal thin film whole thickness is 0.5 to 50%.

At least one surface selected from the first copper layer and the second copper layer may be rust treated.

The rust preventive treatment is preferably performed by any one or two or more selected from chromium (Cr), a silane compound and a nitrogen compound.

According to another aspect of the invention, the first step of forming a core layer made of a metal other than copper (Cu); And a second step of forming a copper layer on both surfaces of the core thin film. A method of manufacturing a multilayer metal thin film for a lithium battery is provided.

In the first step, the core layer using any one selected from aluminum (Al), nickel (Ni), manganese (Mn), zinc (Zn), tin (Sn), and iron (Fe), or two or more alloys. Can be formed.

 In the first step, the core layer is preferably formed so that the surface roughness (Rz) of at least one surface is 0.5 ~ 3.0㎛.

In the second step, the step of rust-proof the surface of the copper layer may be further performed.

According to the present invention, the material cost of copper is reduced due to the structure in which the copper layer is formed only on both sides of the core layer, thereby reducing the manufacturing cost of a current collector for a lithium battery.

In addition, the multilayer metal thin film for lithium batteries provided in accordance with the present invention does not cause detachment because sufficient adhesion is ensured when contacting with the negative electrode active material, and no pinholes are generated in the copper layer, so that the electrolyte of the battery is transferred to the inner core layer. The problem of infiltration and causing corrosion can be prevented.

In addition, since it is possible to prevent the generation of voids during the coating of the active material, it is possible to prevent the phenomenon that the current is concentrated to a specific point of the current collector.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given below, serve to further the understanding of the technical idea of the invention. And should not be construed as limiting.
1 is a cross-sectional view showing the configuration of a metal thin film for a lithium battery according to the prior art;
2 is a cross-sectional view showing the configuration of a metal thin film for a lithium battery according to a preferred embodiment of the present invention;
3 is a flowchart illustrating a manufacturing process of a metal thin film for a lithium battery according to a preferred embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

2 is a cross-sectional view showing the configuration of a metal thin film for a lithium battery according to a preferred embodiment of the present invention.

Referring to FIG. 2, the metal thin film for a lithium battery according to an exemplary embodiment of the present invention includes a core layer 100 formed of at least one layer and a first copper layer 101 formed on both outermost surfaces of the core layer 100. And a second copper layer 102.

The core layer 100 is made of a metal other than copper (Cu). When the metal constituting the core layer 100 is a metal having a relatively low cost compared to copper (Cu), the manufacturing cost of the lithium battery material may be reduced. In addition, when the metal constituting the core layer 100 is a metal that is relatively superior in tensile strength or mechanical reliability compared to copper (Cu), the mechanical properties of the lithium battery material may be improved.

Considering the above points, any one of the metals constituting the core layer 100 is aluminum (Al), nickel (Ni), manganese (Mn), zinc (Zn), tin (Sn), and iron (Fe). At least two or more alloys thereof are preferably employed.

In addition, it is preferable that the surface roughness of one surface and / or the other surface of the core layer 100 is 0.5 to 3.0 μm based on JIS ten point average roughness (Rz). If the surface roughness of the core layer 100 is 3.0 μm or more, pinholes are generated in the process of forming the first copper layer 101 or the second copper layer 102, and the electrolyte solution penetrates the core layer 100 when applied to the fuel cell. This results in corrosion of the core layer 100. In addition, when the surface roughness of the core layer 100 is 0.5 μm or less, the adhesive force at the interface is lowered, so that the negative electrode active material detaches together with the first copper layer 101 or the second copper layer 102 in the fuel cell manufacturing process. This will occur.

The thickness ratio of the first copper layer 101 to the total thickness of the metal thin film or the thickness ratio of the second copper layer 102 to the total thickness of the metal thin film is preferably 0.5 to 50%. When the thickness ratio range is satisfied, the metal thin film may satisfy a thickness, electrical conductivity, material cost condition, and the like suitable for a lithium battery material.

The outer surface of the first copper layer 101 and / or the second copper layer 102 is preferably rust treated with any one or two or more of chromium (Cr), a silane compound and a nitrogen compound.

3 is a flowchart illustrating a manufacturing process of a metal thin film for a lithium battery according to a preferred embodiment of the present invention.

Referring to FIG. 3, a metal thin film for a lithium battery according to a preferred embodiment of the present invention includes a core thin film manufacturing process (step S100), a copper thin film forming process (step S110), and an antirust treatment process (step S120).

In the core thin film production process (step S100), the core layer 100 of the lithium battery metal thin film is formed by rolling a metal other than copper (Cu) or electroplating using a rotary drum to produce a core thin film. Here, the metal other than copper (Cu) is any one of aluminum (Al), nickel (Ni), manganese (Mn), zinc (Zn), tin (Sn) and iron (Fe), or at least two or more of these It is preferable that an alloy is employed.

In the copper thin film forming process (step S110), the first copper layer 101 and the second copper layer 102 are formed by coating a copper thin film on both surfaces of the core layer 100. As a process for coating a copper thin film on the surface of the core layer 100, an electroless plating method, a hot dip plating method, an electrolytic plating method, a sputtering method, a chemical vapor deposition method, or the like may be adopted.

In the antirust treatment process (step S120), one or two or more of chromium (Cr), a silane compound, and a nitrogen compound are coated on the outer surfaces of the first copper layer 101 and the second copper layer 102 to impart a rust prevention function. do.

By the manufacturing process as described above, a metal thin film for lithium battery having a laminated structure of the first copper layer 101 / core layer 100 / second copper layer 102 is provided.

Table 1 below shows the results of evaluating the characteristics of the metal thin film for lithium batteries manufactured according to the examples and comparative examples of the present invention. Samples 1 to 4 in Table 1 are metal thin films for lithium batteries having a laminated structure of the first copper layer 101 / core layer 100 / second copper layer 102 according to the present invention, and samples 5 and 6 are conventionally It is a metal thin film for lithium batteries which has a single layer copper foil structure according to a technique. Samples of the metal thin film for lithium batteries were prepared for the negative electrode current collector.

Referring to Table 1, Samples 1 to 4 are inexpensive compared to Samples 5 and 6 due to the structure in which a copper layer is formed only on both sides of an inner metal layer (core layer 100) made of aluminum (Al). It can be seen that it can be prepared.

On the other hand, in the case of Sample 3, it can be seen that the detachment of the negative electrode active material occurs because the surface roughness of the inner metal layer (core layer 100) is out of the lower limit of 0.5 ~ 3.0㎛. Here, the detachment of the negative electrode active material was determined by applying the negative electrode active material to the outermost layer surface of the metal thin film for lithium battery, and counting the number of desorption portions. To this end, 2 parts by weight of SBR (styrene butadiene rubber) and 2 parts by weight of CMC (carboxymethylcellulose) are mixed with 100 parts by weight of carbon commercially available for the negative electrode active material, a slurry is prepared using distilled water as a solvent, and a doctor blade. Using a (Doctor blade) was applied to the negative electrode active material on a 20cm wide sample to a thickness of 20 ~ 60㎛, dried at 120 ℃ was pressed (Press) at a pressure of 1ton / ㎠. Subsequently, the pressed sample was cut into a size of 10 cm × 10 cm, and then the surface of the sample coated with the negative electrode active material was irradiated using a magnification of 20 magnification, and the number of portions from which the negative electrode active material was detached was counted. It was judged that it was defective when one or more points detached.

In the case of Sample 4, the surface roughness of the inner metal layer (core layer 100) is out of the upper limit of 0.5 ~ 3.0㎛ it can be seen that the pinhole occurs in the outermost layer. Here, the presence or absence of the pinhole was judged by counting the number of discoloration portions by depositing a lithium battery metal thin film in an aqueous sulfuric acid solution. To this end, a sample cut into 10 cm × 10 cm size was immersed in a 10% sulfuric acid aqueous solution for 5 seconds, and then inspected on both sides of the sample using a magnification of 20 times to count the number of discolored parts. If it was abnormal, it was judged to be defective.

As described above, the metal thin film for lithium battery according to the present invention has a manufacturing cost higher than that of a single layer copper foil due to the structure in which the core layer 100 is interposed between the first copper layer 101 and the second copper layer 102. Since the adhesion between the first copper layer 101 and the second copper layer 102 and the core layer 100 is large, the detachment of the negative electrode active material can be prevented and the occurrence of pinholes on the outermost layer surface can be suppressed. There is remarkable effect of preventing the core layer 100 from corrosion.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto and will be described below by the person skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims.

100: core layer 101: first copper layer
102: second copper layer

Claims (10)

In the metal thin film used as a lithium battery material,
A core layer made of a metal other than copper (Cu);
A first copper layer formed on one surface of the core layer: and
And a second copper layer formed on the other surface of the core layer. The method of claim 1,
The core layer is any one selected from aluminum (Al), nickel (Ni), manganese (Mn), zinc (Zn), tin (Sn) and iron (Fe), or a lithium battery, characterized in that made of two or more alloys Multilayer metal thin film. The method of claim 1,
The surface roughness (Rz) of at least one of both surfaces of the said core layer is 0.5-3.0 micrometers, The multilayer metal thin film for lithium batteries characterized by the above-mentioned. The method of claim 1,
The thickness ratio of the first copper layer or the second copper layer to the total thickness of the metal thin film is a lithium metal multilayer metal thin film, characterized in that 0.5 to 50%. The method of claim 1,
The surface of at least one selected from the first copper layer and the second copper layer is subjected to rust treatment, characterized in that the multilayer metal thin film for lithium batteries. The method of claim 5,
The rust preventive treatment is a multilayer metal thin film for lithium batteries, characterized in that made of one or two or more selected from chromium (Cr), a silane compound and a nitrogen compound. In the method of manufacturing a metal thin film used as a lithium battery material,
A first step of forming a core layer made of a metal other than copper (Cu); And
Forming a copper layer on both sides of the core thin film; manufacturing method of a multilayer metal thin film for a lithium battery comprising a. The method of claim 7, wherein in the first step,
The core layer is formed using any one selected from aluminum (Al), nickel (Ni), manganese (Mn), zinc (Zn), tin (Sn), and iron (Fe), or two or more alloys. Method for producing a multilayer metal thin film for a lithium battery. The method of claim 7, wherein in the first step,
The core layer is a method for producing a multilayer metal thin film for lithium batteries, characterized in that the surface roughness (Rz) of at least one surface is formed to be 0.5 ~ 3.0㎛. The method of claim 7, wherein in the second step,
The method of manufacturing a multilayer metal thin film for a lithium battery, characterized in that it further comprises; rust-treating the surface of the copper layer.

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