KR20170034773A - Metal mesh foil for current collector of lithium secondary battery, electrode for lithium secondary battery and lithium secondary battery comprising the same - Google Patents

Abstract

The present invention relates to a metal mesh foil for current collector of a lithium secondary battery, the metal mesh foil having a hydrophobic deposition film formed on a surface thereof, being a deposition layer in which a hydrophobic material is deposited, and having a thickness range of 1-100 . Since the metal mesh foil for current collector of a lithium secondary battery according to the present invention can solve a flowing down of slurry that may occur during coating of the slurry on the metal mesh foil by forming a hydrophobic deposition layer on a surface of the metal mesh foil to modify the property of the metal mesh foil to the hydrophobicity in a process of a lithium secondary battery, the metal mesh foil can be usefully used in the manufacturing of the lithium secondary battery, and the lithium secondary battery including the metal mesh foil can exhibit excellent performances in swelling issue, output property and lifespan property.

Description

TECHNICAL FIELD The present invention relates to a metal mesh thin plate for a current collector of a lithium secondary battery, an electrode for a lithium secondary battery including the metal mesh thin plate, and a lithium secondary battery comprising the same. BACKGROUND ART < RTI ID = 0.0 >

The present invention relates to a metal mesh thin plate for a current collector of a lithium secondary battery, an electrode for a lithium secondary battery comprising the metal thin plate, and a lithium secondary battery, and more particularly to a metal mesh thin plate modified by a hydrophobic vapor deposition film formed on the surface thereof, An electrode for a lithium secondary battery including the same, and a lithium secondary battery.

As technology development and demand for mobile devices have increased, there has been a rapid increase in demand for secondary batteries as energy sources. Among such secondary batteries, lithium secondary batteries, which exhibit high energy density and operating potential, long cycle life, Batteries have been commercialized and widely used.

The lithium secondary battery generally comprises a positive electrode containing a positive electrode active material, a negative electrode including a negative electrode active material, a separator and an electrolyte, and is charged and discharged by intercalation-decalation of lithium ions. The lithium secondary battery has a high energy density, a large electromotive force, and a high capacity, so it is applied to various fields.

The positive electrode and the negative electrode of the lithium secondary battery are manufactured by coating a metal thin plate such as aluminum or copper, respectively, with a cathode active material and a negative electrode active material, followed by rolling. However, in the case of an electrode plate subjected to a post-process after the active material is coated on a collector such as a flat aluminum or copper foil plate, the active material is peeled off from the thin metal plate, causing swelling, Life characteristics and the like are deteriorated.

In order to overcome this problem, attempts have been made to prevent the above-mentioned peeling phenomenon by coating a metal thin plate with a mesh, and coating the metal thin plate with an active material.

However, when the slurry containing the active material is coated on the mesh-treated metal thin plate, there is a problem in that the slurry flows down between the meshes.

Therefore, it is necessary to develop a new technology that can solve the above-described problems in the process, while using a metal thin plate processed as a current collector of the lithium secondary battery.

A problem to be solved by the present invention is to provide a method for producing a metal mesh thin plate by forming a hydrophobic vapor deposition film on the surface of a metal mesh thin plate and modifying the hydrophobic vapor deposition film to a hydrophobic property, Which is capable of solving the problems of the metal mesh laminate for a lithium secondary battery.

It is another object of the present invention to provide a current collector for a lithium secondary battery including a metal mesh thin plate for a current collector of the lithium secondary battery and an electrode for a lithium secondary battery comprising the same.

Another object of the present invention is to provide a lithium secondary battery including the electrode for the lithium secondary battery.

In order to solve the above problems,

A metal mesh thin plate having a hydrophobic deposition film formed on its surface,

The hydrophobic vapor deposition layer is a vapor deposition layer on which a hydrophobic substance is deposited, and has a thickness of 1 to 100 A, and provides a metal mesh thin plate for a current collector for a lithium secondary battery.

In order to solve the above-mentioned other problems,

A current collector for a lithium secondary battery including a metal mesh thin plate for a current collector of the lithium secondary battery, and an electrode for a lithium secondary battery including the current collector for the lithium secondary battery.

Further, in order to solve the above-mentioned problems,

The present invention also provides a lithium secondary battery including the electrode for the lithium secondary battery.

The metal mesh thin plate for a current collector of a lithium secondary battery of the present invention may be formed by forming a hydrophobic vapor deposition film on the surface of the metal mesh thin plate to modify it to be hydrophobic so that when the slurry is coated on the metal mesh thin plate in the process of the lithium secondary battery, The present invention can provide a lithium rechargeable battery including the lithium rechargeable battery which is excellent in the swelling problem, the output characteristics, the life characteristics, etc. Can be exercised.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram schematically showing a cross section of a metal mesh thin plate for a current collector of a lithium secondary battery according to an example of the present invention. Fig.
2 is a plan view schematically showing a metal mesh thin plate for a current collector of a lithium secondary battery according to an example of the present invention.

Hereinafter, the present invention will be described in detail in order to facilitate understanding of the present invention.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

A metal mesh thin plate for a current collector of a lithium rechargeable battery according to the present invention is a metal mesh thin plate having a hydrophobic deposition film formed on its surface, wherein the hydrophobic deposition film is a vapor deposition film deposited with a hydrophobic substance and has a thickness of 1 to 100 angstroms.

The metal mesh thin plate may have fine unevenness formed on a thin metal plate or may have a mesh screen shape or may have a plurality of holes formed on a thin metal plate. In the specification of the present invention, the metal thin plate may be in the form of a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven fabric, or the like.

In the metal mesh thin plate for current collector of a lithium secondary battery according to an example of the present invention, the hydrophobic substance may be an organosilane compound, and specific examples of the organosilane compound include triethoxyvinylsilane, dimethylethoxyvinylsilane , 3-mercaptopropyltrimethoxysilane, trimethoxyfluorosilane, and trichloro (1H, 1H, 2H, 2H-perfluorooctyl) silane. More specifically, the hydrophobic substance may be trichloro (1H, 1H, 2H, 2H-perfluorooctyl) silane.

The vapor deposition layer may be formed by depositing a single layer or several layers through a chemical vapor deposition (CVD) method or the like.

The vapor deposition layer may have a thickness of 1 to 100 angstroms, specifically, a thickness of 1 to 50 angstroms, a thickness of 10 to 50 angstroms, and more specifically, a thickness of 10 to 30 angstroms.

When the vapor deposition layer has a thickness of 1 A or more, the surface of the metal mesh thin plate may be modified to appropriately hydrophobize. When the vapor deposition layer has a thickness of 100 A or less, resistance of the vapor deposition layer increases to form the vapor deposition layer It is possible to prevent the resistance value of the metal mesh thin plate from excessively increasing.

Specifically, when the hydrophobic vapor deposition layer is formed of the metal mesh thin plate, the metal mesh thin plate can be smoothly hydrophobically modified as the thickness of the metal mesh thin plate is increased. However, since the resistance value of the metal mesh thin plate having the vapor deposition layer is increased The electrochemical characteristics of the electrode for a lithium secondary battery and the lithium secondary battery containing the same are deteriorated, and therefore, it is necessary to control the thickness of the hydrophobic vapor deposition film to an appropriate degree. On the other hand, when the hydrophobic deposition film is deposited as thinly as possible in a thickness range of less than the proper range, it is advantageous in that the increase in the resistance value of the metal mesh thin plate on which the hydrophobic deposition film is formed can be reduced, The degree of modifying the surface of the metal mesh thin plate to be hydrophobic becomes insignificant. This is because when the thickness of the hydrophobic deposition layer is too small, a portion corresponding to a defect initially generated in the process of depositing the hydrophobic substance is not filled with the hydrophobic substance deposited thereafter And is not modified by the hydrophobic property. Therefore, in order to impart the hydrophobic property to the metal mesh thin plate, the thickness of the hydrophobic vapor deposition film must satisfy the above range in order to maintain the resistance value to an appropriate level.

The metal mesh thin plate for the current collector of the lithium secondary battery is modified to be hydrophobic through the hydrophobic vapor deposition film so that the metal mesh thin plate for current collector of the lithium secondary battery has a water contact angle of 80 to 130 °, A water contact angle of from 130 DEG to 130 DEG, a water contact angle of from 105 DEG to 125 DEG, more specifically from 105 DEG to 110 DEG.

In the case where the water contact angle of the metal mesh thin plate for current collector of the lithium secondary battery is 80 ° or more, when the slurry is coated on the metal mesh thin plate using the metal mesh thin plate for current collector of the lithium secondary battery as a current collector, It is possible to prevent the slurry from flowing down due to the interaction with the slurry due to the hydrophobicity due to the interaction with the slurry. When the water contact angle is 130 ° or less, the thickness of the hydrophobic vapor deposition film becomes excessively thick Can be prevented from being excessively increased.

Accordingly, the metal mesh thin plate having the hydrophobic deposition film formed on the surface thereof can have a resistance value of 105 to 130% based on the metal mesh thin film on which the hydrophobic vapor deposition film is not formed, specifically, a resistance value of 105 to 120% And more specifically may have a resistance value of 105 to 110%.

The resistance value of the metal mesh thin plate for the current collector of the lithium secondary battery may be 0.9 to 1.3 m? · Cm ² and may be specifically 1 to 1.22 m? · Cm ² and 1.05 to 1.22 m? · Cm ² , more specifically 1.05 To 1.13 m? · Cm < ² >.

The current collector of the lithium secondary battery is not particularly limited and may be used as a current collector for a positive electrode or a current collector for a negative electrode, but may be a current collector for a negative electrode of a lithium secondary battery.

The metal mesh thin plate is not particularly limited as long as it is a metal mesh thin plate used as an anode current collector of a lithium secondary battery. Examples of the metal mesh thin plate include copper, gold, stainless steel, aluminum, nickel, titanium, Copper, or stainless steel surface-treated with carbon, nickel, titanium, or silver; Or an aluminum-cadmium alloy thin plate, and more specifically, a copper mesh thin plate.

The thickness of the metal mesh thin plate may be from 3 탆 to 500 탆.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a metal mesh thin plate for a current collector of a lithium secondary battery of the present invention will be described in detail with reference to the drawings, but the drawings are for illustrating the present invention only and the scope of the present invention is not limited thereto. In the drawings of the present invention, the size of each component may be exaggerated for illustrative purposes and may differ from the size actually applied.

FIG. 1 is a schematic cross-sectional view of a metal mesh thin plate for a current collector of a lithium secondary battery according to an embodiment of the present invention. FIG. 2 is a schematic view of a metal mesh thin plate for a current collector of a lithium secondary battery according to an embodiment of the present invention And a plan view thereof.

1, a metal mesh thin plate 100 for a current collector of a lithium secondary battery according to an exemplary embodiment of the present invention is formed on a metal mesh thin plate 110, that is, on one side of a metal mesh thin plate 110 ) Or the both surfaces (Fig. 1 (b)).

Referring to FIG. 2, when a metal mesh thin plate 100 for a current collector for a lithium secondary battery according to an exemplary embodiment of the present invention is placed on a plane, a mesh 101 (see FIG. 2) of a metal mesh thin plate 100 for a current collector of a lithium secondary battery, 1), and the hydrophobic vapor deposition film 120 is formed on the surface of the metal mesh thin plate 110 (see FIG. 1) to form the mesh 101 It is possible to prevent the problem that the slurry flows down into the space of the mesh 101 due to its affinity with the slurry when the slurry is coated.

The metal mesh thin plate for a current collector of the lithium secondary battery according to the present invention can be effectively used as a collector of a lithium secondary battery. Accordingly, the present invention provides a lithium secondary battery comprising a lithium metal secondary battery, A current collector for a secondary battery, and an electrode for a lithium secondary battery including the current collector for the lithium secondary battery.

The current collector for a lithium secondary battery may be a current collector for a negative electrode of a lithium secondary battery, and thus the electrode for the lithium secondary battery may be a negative electrode.

The present invention also provides a lithium secondary battery including the electrode for the lithium secondary battery.

The lithium secondary battery may include a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode.

The anode may be prepared by a conventional method known in the art. For example, a slurry may be prepared by mixing and stirring a solvent, a binder, a conductive material, and a dispersant as necessary in a cathode active material, and then coating (coating) the mixture on a current collector of a metal material, have.

The current collector of the metal material is a metal having high conductivity and is a metal which can easily adhere to the slurry of the cathode active material and is not particularly limited as long as it has high conductivity without causing chemical change in the battery in the voltage range of the battery But not limited to, stainless steel, aluminum, nickel, titanium, sintered carbon, or aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, or the like. In addition, fine unevenness may be formed on the surface of the current collector to increase the adhesive force of the positive electrode active material. The current collector can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric, and may have a thickness of 3 to 500 탆.

The cathode active material may include, for example, lithium cobalt oxide (LiCoO ₂ ); Lithium nickel oxide (LiNiO _2); Li [Ni _a Co _b Mn _c M ¹ _d ] O ₂ wherein M ¹ is any one or a combination of two or more elements selected from the group consisting of Al, Ga and In, B? 0.5, 0? C? 0.5, 0? D? 0.1, a + b + c + d = 1); ^{_{Li (Li e M 2 fe-}} f 'M 3 f') O 2 - g A g ( wherein, 0≤e≤0.2, 0.6≤f≤1, 0≤f'≤0.2, 0≤g≤0.2 and M ² is at least one element selected from the group consisting of Mn, Ni, Co, Fe, Cr, V, Cu, Zn and Ti, M ³ is at least one element selected from the group consisting of Al, And A is at least one member selected from the group consisting of P, F, S and N) or a compound substituted with one or more transition metals; Li _{1 + h} Mn _{2 - h} O ₄ (where 0 _{? H?} 0.33), lithium manganese oxides such as LiMnO ₃ , LiMn ₂ O ₃ and LiMnO ₂ ; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; Formula ^{_{LiNi 1 - i M 4 i O}} 2 Ni site type lithium nickel oxides represented by (wherein, M = ^4, and Co, Mn, Al, Cu, Fe, Mg, B or Ga, 0.01≤y≤0.3); Formula ^{_{LiMn 2 - j M 5 j O}} 2 ( ^{wherein, M 5 = Co, Ni,} Fe, Cr, and Zn, or Ta, 0.01≤y≤0.1) or ^{_{Li 2 Mn 3 M 6 O 8}} ( wherein, M ⁶ = Fe, Co, Ni, Cu or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; LiFe ₃ O ₄ , Fe ₂ (MoO ₄ ) ₃ , and the like, but are not limited thereto.

Examples of the solvent for forming the positive electrode include organic solvents such as NMP (N-methylpyrrolidone), DMF (dimethylformamide), acetone, and dimethylacetamide, and water. These solvents may be used alone or in combination of two or more Can be mixed and used. The amount of the solvent used is sufficient to dissolve and disperse the cathode active material, the binder and the conductive material in consideration of the coating thickness of the slurry and the production yield.

Examples of the binder include polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate, Polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM) Sulfonated EPDM, styrene butadiene rubber (SBR), fluorine rubber, poly acrylic acid, and polymers in which hydrogen is substituted with Li, Na, or Ca, or Various kinds of binder polymers such as various copolymers can be used.

The conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, and examples thereof include graphite such as natural graphite and artificial graphite; Carbon black such as acetylene black, Ketjen black, channel black, panes black, lamp black, and thermal black; Conductive fibers such as carbon fiber and metal fiber; Conductive tubes such as carbon nanotubes; Metal powders such as fluorocarbon, aluminum and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used. The conductive material may be used in an amount of 1 wt% to 20 wt% based on the total weight of the positive electrode slurry.

The dispersing agent may be an aqueous dispersing agent or an organic dispersing agent such as N-methyl-2-pyrrolidone.

The negative electrode may be prepared by a conventional method known in the art. For example, an additive such as a binder, a conductive material, and a thickener may be mixed and stirred with the negative active material to prepare a negative active material slurry, To a current collector for a lithium secondary battery, drying it, and then compressing it.

As the negative electrode active material used for the negative electrode, a carbon material capable of occluding and releasing lithium ions, lithium metal, silicon or tin may be used. Preferably, carbon materials can be used, and carbon materials such as low-crystalline carbon and highly-crystalline carbon can be used. Examples of the low crystalline carbon include soft carbon and hard carbon. Examples of highly crystalline carbon include natural graphite, kish graphite, pyrolytic carbon, liquid crystal pitch carbon fiber high-temperature sintered carbon such as mesophase pitch based carbon fiber, meso-carbon microbeads, mesophase pitches and petroleum or coal tar pitch derived cokes.

The binder may be used to bind the negative electrode active material particles to maintain the formed body. Any conventional binder used in preparing the slurry for the negative electrode active material is not particularly limited, and examples thereof include polyvinyl alcohol, carboxymethyl cellulose, Polyvinylidene fluoride (PTFE), polyvinylidene fluoride (PVdF), polyethylene or polypropylene, and the like can be used. In addition, an acrylic resin such as acrylic resin (polyvinyl chloride), polyvinyl pyrrolidone, polytetrafluoroethylene Acrylonitrile-butadiene rubber, styrene-butadiene rubber, styrene-butadiene rubber, and acrylic rubber, or a mixture of two or more thereof. The aqueous binders are economical, environmentally friendly, harmless to the health of workers, and are superior to non-aqueous binders, and have a better binding effect than non-aqueous binders. Thus, the ratio of the active materials of the same volume can be increased and the capacity of the aqueous binders can be increased. Preferably styrene-butadiene rubber can be used.

The binder may be contained in an amount of 10 wt% or less, specifically 0.1 wt% to 10 wt%, based on the total weight of the slurry for the negative electrode active material. If the content of the binder is less than 0.1 wt%, the effect of the binder is insufficient, which is undesirable. If the content of the binder is more than 10 wt%, the relative content of the active material may decrease to increase the binder content. not.

The conductive material is not particularly limited as long as it has conductivity without causing chemical changes in the battery, and examples of the conductive material include graphite such as natural graphite and artificial graphite; Carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; And conductive materials such as polyphenylene derivatives. The conductive material may be used in an amount of 1 wt% to 9 wt% with respect to the total weight of the slurry for the negative electrode active material.

As the thickener, any thickener conventionally used in a lithium secondary battery may be used, and examples thereof include carboxymethyl cellulose (CMC) and the like.

As the separator, a conventional porous polymer film conventionally used as a separator, such as a polyolefin-based polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene-butene copolymer, an ethylene-hexene copolymer and an ethylene-methacrylate copolymer Porous nonwoven fabric such as high melting point glass fiber, polyethylene terephthalate fiber or the like may be used as the nonwoven fabric, but the present invention is not limited thereto.

The lithium salt that can be used as the electrolyte used in the present invention may be any of those commonly used in electrolytes for lithium secondary batteries, and examples thereof include F ^- , Cl ^- , Br ^- , I ^- , NO _{3 ^{-, N (CN) 2 -}} , BF 4 -, ClO 4 -, PF 6 -, (CF 3) 2 PF 4 -, (CF 3) 3 PF 3 -, (CF 3) 4 PF 2 -, (CF ^{_{3) 5 PF -, (CF}} 3) 6 P -, CF 3 SO 3 -, CF 3 CF 2 SO 3 -, (CF 3 SO 2) 2 N -, (FSO 2) 2 N -, CF 3 CF 2 ^{_{(CF 3) 2 CO -,}} (CF 3 SO 2) 2 CH -, (SF 5) 3 C -, (CF 3 SO 2) 3 C -, CF 3 (CF 2) 7 SO 3 -, CF 3 CO ₂ ^- , CH ₃ CO ₂ ^- , SCN ^-, and (CF ₃ CF ₂ SO ₂ ) ₂ N ^- .

Examples of the electrolyte used in the present invention include an organic-based liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, and a molten inorganic electrolyte that can be used in the production of a lithium secondary battery. no.

The external shape of the lithium secondary battery of the present invention is not particularly limited, but may be a cylindrical shape, a square shape, a pouch shape, a coin shape, or the like using a can.

The lithium secondary battery according to the present invention can be used not only in a battery cell used as a power source of a small device but also as a unit cell in a middle- or large-sized battery module including a plurality of battery cells.

Preferable examples of the above medium and large-sized devices include, but are not limited to, electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and electric power storage systems.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples, but the present invention is not limited by these Examples and Experimental Examples. The embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of the present invention are provided to enable those skilled in the art to more fully understand the present invention.

Example 1

2 ㎕ of a 50 탆 thick copper mesh foil (100 mesh, wire diameter 50 탆) and trichloro (1H, 1H, 2H, 2H-perfluorooctyl) silane having a plurality of holes formed on the surface thereof were placed in a vacuum drier (1H, 1H, 2H, 2H-perfluorooctyl) silane was formed on the surface of the copper mesh foil by heating at 90 ° C. for 60 minutes in a vacuum state to form a metal film on which a hydrophobic deposition film of trichloro Mesh laminate. At this time, the thickness of the hydrophobic deposition film was about 30 Å.

Example 2

(1H, 1H, 1H-1H) was added to the surface of the copper mesh foil in the same manner as in Example 1, except that the amount of trichloro (1H, 1H, 2H, 2H-perfluorooctyl) , 2H, 2H-perfluorooctyl) silane formed thereon was prepared. The thickness of the hydrophobic vapor deposition film was about 10 Å.

Example 3

(1H, 1H, 1H) was added to the surface of the copper mesh foil in the same manner as in Example 1, except that the amount of trichloro (1H, 1H, 2H, 2H-perfluorooctyl) , 2H, 2H-perfluorooctyl) silane formed thereon was prepared. The thickness of the hydrophobic vapor deposition film was about 50 Å.

Example 4

(1H, 1H, 1H) was added to the surface of the copper mesh foil in the same manner as in Example 1, except that the amount of trichloro (1H, 1H, 2H, 2H-perfluorooctyl) , 2H, 2H-perfluorooctyl) silane formed thereon was prepared. The thickness of the hydrophobic vapor deposition film was about 100 Å.

Comparative Example 1

A copper mesh foil (100 mesh, wire diameter 50 占 퐉) having a thickness of 50 占 퐉 and having a plurality of holes formed on its surface was used without any treatment.

Comparative Example 2

A hydrophobic vapor deposition film was formed on the copper mesh foil in the same manner as in Example 1 except that 11 μl of trichloro (1H, 1H, 2H, 2H-perfluorooctyl) silane was used in Example 1, A metal mesh thin plate was prepared. The thickness of the hydrophobic deposition film was about 110 Å.

Comparative Example 3

A hydrophobic vapor deposition film was formed on the copper mesh foil in the same manner as in Example 1, except that 20 l of trichloro (1H, 1H, 2H, 2H-perfluorooctyl) silane was used in Example 1, A metal mesh thin plate was prepared. At this time, the thickness of the hydrophobic deposition film was about 200 Å.

Comparative Example 4

A hydrophobic vapor deposition film was formed on the copper mesh foil in the same manner as in Example 1, except that 0.2 mu l of trichloro (1H, 1H, 2H, 2H-perfluorooctyl) silane was used in Example 1, A metal mesh thin plate was prepared. At this time, the thickness of the hydrophobic vapor deposition film was between 0.5 and 1 angstrom.

Comparative Example 5

A hydrophobic vapor deposition film was formed on the copper mesh foil in the same manner as in Example 1, except that 0.1 mu l of trichloro (1H, 1H, 2H, 2H-perfluorooctyl) silane was used in Example 1, A metal mesh thin plate was prepared. At this time, the thickness of the hydrophobic deposition film was between 0.1 and 0.5 Å.

Experimental Example 1: Evaluation of surface properties

The contact angle was measured using a contact angle meter (pheonix300, manufactured by SEO Co.) on the metal mesh thin plate for current collectors of the lithium secondary batteries of Examples 1 to 4 and Comparative Examples 1 to 5, Were measured. The contact angle measurement was performed by placing a specimen on a flat plate, dropping a small amount of water using a syringe cylinder, placing the lens of the camera in a direction perpendicular to the substrate surface (side surface of the substrate) The contact angle was measured by a method of measuring the contact angle. The results are shown in Table 1 below.

Water contact angle (°) Surface resistance (mΩ · cm ² ) Example 1 110 1.1 Example 2 105 1.05 Example 3 110 1.13 Example 4 125 1.22 Comparative Example 1 60 One Comparative Example 2 130 1.25 Comparative Example 3 150 1.4 Comparative Example 4 70 One Comparative Example 5 65 One

Referring to Table 1, since the metal mesh thin plates of Examples 1 to 4 have a water contact angle of 105 ° to 125 °, when compared with the 60 ° water contact angle of Comparative Example 1 in which a hydrophobic vapor deposition film is not formed, And it was confirmed that the surface was modified.

The metal mesh thin plates of Comparative Examples 2 and 3 exhibited water contact angles of 130 ° and 150 °, respectively, and it was confirmed that the surface modification to hydrophobicity was most performed. However, as the hydrophobic vapor deposition film becomes thicker, , Respectively.

On the other hand, in the case of Comparative Examples 4 and 5, it was confirmed that the thickness of the hydrophobic vapor deposition layer did not reach an appropriate thickness, and the water contact angles were only 65 ° and 70 °, and the surface modification was not performed properly.

Experimental Example 2: Evaluation of affinity with slurry

Negative electrode slurry was prepared by mixing 86 wt% of graphite, 1 wt% of Denka black (conductive material), 2 wt% of SBR (binder), and 1 wt% of CMC (thickener) as a negative active material. The prepared negative electrode active material slurry was applied to a metal mesh thin plate for collectors of lithium secondary batteries of Example 1 and Comparative Examples 1, 3 and 4 in an amount capable of forming an active material layer having a thickness of 100 탆, And dried.

The thickness of the active material layer formed on each was measured and shown in Table 2.

The thickness of the formed active material layer
(Except copper mesh) Example 1 100 탆 Comparative Example 1 10 탆 Comparative Example 3 100 탆 Comparative Example 4 15 탆

As shown in Table 2, the metal mesh thin plates of Examples 1 and Comparative Example 3 having surfaces with water contact angles of 110 ° and 150 °, respectively, were modified to be sufficiently hydrophobic that the slurry did not flow between the meshes and the thickness of the desired active material layer The metal mesh thin sheets of Comparative Examples 1 and 4 in which the surface was not sufficiently hydrophobic could cause the slurry to flow down between the meshes to cause the active material layer to have a thickness of only 10 占 퐉 and 15 占 퐉 And it was confirmed that the coating of the anode active material slurry was not achieved as intended.

Example 5: Preparation of lithium secondary battery

An anode slurry was prepared by mixing 98 wt% of artificial graphite, 1 wt% of SBR (binder), and 1 wt% of CMC (thickener) as an anode active material with NMP as a solvent. The prepared negative electrode active material slurry was applied to a metal mesh thin plate for a current collector of a lithium secondary battery of Example 1 in an amount capable of forming an active material layer having a thickness of 100 mu m and then dried and then subjected to a roll press Thereby preparing a negative electrode.

A separator composed of three layers of polypropylene / polyethylene / polypropylene (PP / PE / PP) was interposed between the anode and the Li metal thus produced, and then EC (ethylene carbonate): DEC (diethyl carbonate): EMC (ethyl methyl carbonate) = 4: 3: 3 (volume ratio) was dissolved LiPF ₆ electrolyte in a mixed solvent at a concentration of 1 M was injected into a non-aqueous electrolyte prepared was prepared a coin-type half cell.

Comparative Example 6: Preparation of lithium secondary battery

Except that a metal mesh thin plate for current collector of the lithium secondary battery of Comparative Example 1 was used in place of the metal mesh thin plate for current collector of the lithium secondary battery of Example 1 as the negative electrode collector in Example 5, To prepare a negative electrode.

However, in the production of the negative electrode, when the metal mesh thin plate for the current collector of the lithium secondary battery of Comparative Example 1 was used, the slurry flowed down between the meshes of the metal mesh thin plate, As a result, it was impossible to manufacture a negative electrode.

Comparative Example 7: Preparation of lithium secondary battery

Except that a copper foil having a smooth surface and a thickness of 50 占 퐉 was used in place of the metal mesh thin plate for current collector of the lithium secondary battery of Example 1 as the negative electrode collector in Example 5, To prepare a coin type half cell.

Experimental Example 3: Measurement of Discharge Capacity and Thickness of Cathode

The charging and discharging current density was 0.2 C, the charging end voltage was 0.05 V (Li / Li ⁺ ) and the discharge end voltage was 1.5 V (Li / Li) Li ^< ⁺ >). Subsequently, the discharge capacity was measured at a charge current density of 0.2 C and a discharge current density of 2 C, and the discharge capacity was divided by the second discharge capacity to determine the 2 C discharge capacity (%). The results are shown in Table 3 below.

Charging and discharging tests were carried out up to 15 times under the same conditions as above. Then, the battery was charged with a charging current density of 0.2 C, and then the battery was disassembled to measure the thickness of the negative electrode.

The thickness of the negative electrode prepared in Example 5 and Comparative Example 7 was compared with the thickness of the negative electrode after the 15 times charge and discharge test and the rate of increase in the thickness of the negative electrode after 15 charge and discharge tests is shown in Table 3 below.

2 C
Discharge capacity (%) Cathode Thickness Growth Rate after 15 Charging / Discharging (%) Example 5 99% 23% Comparative Example 6 -
(Negative electrode production not possible) -
(Negative electrode production not possible) Comparative Example 7 97% 33%

(Comparative Example 7) in which a negative electrode was manufactured using the metal mesh thin plate of Example 1 (Example 5) and a negative electrode was manufactured using a general copper foil (Comparative Example 7) It was confirmed that the discharge capacity of the doll half cell was excellent. As a result, it was confirmed that the metal mesh thin plate having the hydrophobic deposition film on the surface thereof was more effectively coated with the negative electrode active material slurry, so that the output characteristics of the electrode were improved as compared with the case of using a general copper foil.

In the case of a metal mesh thin plate having a hydrophobic deposition film formed on its surface, the adhesion of the negative electrode active material slurry is superior to that of the general copper foil in that the thickness increase rate of the negative electrode prepared in Example 5 after 15 charge / Which is smaller than the thickness increase rate of the negative electrode prepared in this study.

In addition, when the negative electrode active material slurry is coated on the surface of the metal mesh thin plate, the negative electrode active material slurry flows down and the electrode coating is not smoothly performed, thereby making it difficult to manufacture the negative electrode (Comparative Example 6) It can be solved by forming a hydrophobic vapor deposition film.

100: Metal mesh thin plate for current collector of lithium secondary battery
101: Mesh
110: Metal mesh sheet
120: hydrophobic deposition film

Claims (16)

A metal mesh thin plate having a hydrophobic deposition film formed on its surface,
Wherein the hydrophobic vapor deposition layer is a vapor deposition layer on which a hydrophobic substance is deposited and has a thickness of 1 to 100 angstroms.
The method according to claim 1,
Wherein the hydrophobic substance is an organosilane-based compound.
3. The method of claim 2,
The organosilane compound may be at least one selected from the group consisting of triethoxyvinylsilane, dimethylethoxyvinylsilane, 3-mercaptopropyltrimethoxysilane, trimethoxyfluorosilane and trichloro (1H, 1H, 2H, 2H-perfluorooctyl ) Silane, wherein at least one selected from the group consisting of silicon carbide and silicon carbide is used.
The method according to claim 1,
Wherein the hydrophobic substance is trichloro (1H, 1H, 2H, 2H-perfluorooctyl) silane.
The method according to claim 1,
Wherein the hydrophobic vapor deposition layer is formed by chemical vapor deposition (CVD).
The method according to claim 1,
Wherein the metal mesh thin plate for a current collector of the lithium secondary battery has a water contact angle of 80 to 130 °.
The method according to claim 1,
Wherein the metal mesh thin plate on which the hydrophobic deposition film is formed has a resistance value of 105 to 130% based on the metal mesh thin plate on which the hydrophobic deposition film is not formed.
The method according to claim 1,
Wherein the metal mesh thin plate for a current collector of the lithium secondary battery has a resistance value of 0.9 to 1.3 m? Cm ² .
The method according to claim 1,
Wherein the current collector of the lithium secondary battery is a current collector for a negative electrode.
The method according to claim 1,
Wherein the metal mesh thin plate is selected from the group consisting of copper, gold, stainless steel, aluminum, nickel, titanium, sintered carbon; Copper, or stainless steel surface-treated with carbon, nickel, titanium, or silver; Or an aluminum-cadmium alloy mesh laminate for a lithium secondary battery.
The method according to claim 1,
Wherein the metal mesh thin plate is a copper mesh thin plate, and a metal mesh thin plate for a current collector for a lithium secondary battery.
The method according to claim 1,
Wherein the metal mesh thin plate has a thickness of 3 to 500 占 퐉.
An electrode for a lithium secondary battery comprising a metal mesh thin plate for a current collector of a lithium secondary battery according to any one of claims 1 to 12.
14. A current collector for a lithium secondary battery according to claim 13 and an electrode for a lithium secondary battery comprising the active material.
15. The method of claim 14,
Wherein the active material is a negative electrode active material.
A lithium secondary battery comprising the electrode for a lithium secondary battery according to claim 15.

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