WO2018070728A1 - Anode for lithium metal secondary battery and lithium metal secondary battery comprising same - Google Patents

Abstract

The present invention relates to an anode for a lithium metal secondary battery, the anode having excellent lifespan characteristics and being less prone to form irregular dendrites on a surface thereof, and a lithium metal secondary battery comprising the same. The anode according to the present invention includes a polymer layer arranged in a lattice structure, with empty spaces interposed therein, to increase in specific surface area and thus to make uniform distribution of current densities therein, thereby exhibiting excellent lifespan characteristics and restraining the formation of irregular dendrites.

Description

Anode for lithium metal secondary battery and lithium metal secondary battery comprising same

[Citations with Related Applications]

This application claims the benefit of priority based on Korean Patent Application Nos. 10-2016-0131411 filed on October 11, 2016 and Korean Patent Application No. 10-2017-0125952 filed on September 28, 2017, and all contents disclosed in the documents of the Korean patent application. Is included as part of this specification.

[Technical Field]

The present invention relates to a lithium metal secondary battery negative electrode and a lithium metal secondary battery comprising the same having excellent life characteristics and less irregular dendritic formation on the surface.

 As the development and demand for mobile devices increases, the demand for secondary batteries as energy sources is rapidly increasing. Among them, lithium secondary batteries exhibiting high energy density and operating potential and low self discharge rate have been commercialized.

The lithium metal secondary battery is the first commercially available lithium secondary battery and uses lithium metal as a negative electrode. However, the lithium metal secondary battery is a lithium resin phase formed on the surface of the lithium metal negative electrode, the volume expansion of the cell, the gradual decrease in capacity and energy density, short circuit caused by the continuous growth of the dendrite, cycle life decrease and cell stability problems (explosion and Ignition) production stopped just a few years after commercialization. Thus, a carbon-based negative electrode was used instead of lithium metal, which is more stable and stably stores lithium in a lattice or empty space, and commercialization and dissemination of a full-scale lithium secondary battery has been advanced due to the use of the carbon-based negative electrode.

To date, lithium secondary batteries are mainly made of carbon-based or non-carbon anode materials, and most of the development of anode materials is made of carbon-based (graphite, hard carbon, soft carbon, etc.) and non-carbon-based (silicon, tin, titanium oxide, etc.) materials. Focused on the fields. However, carbon-based materials do not exceed the theoretical capacity of 400 mAh / g, non-carbon based materials are more than 1000 mAh / g, but there is a problem of volume expansion and performance degradation during charging and discharging.

On the other hand, in recent years, as the medium-large-size lithium secondary battery is activated, high capacity and high energy density characteristics are required, but existing carbon-based or non-carbon-based negative electrode materials have a limit in meeting such performance.

Accordingly, recent studies are being actively conducted to utilize lithium metal like lithium-air batteries, and at the same time, interest in lithium metal secondary batteries is increasing again. Lithium is very light and has the potential to achieve excellent energy densities above theoretical capacity of 3800 mAh / g.

However, there are a number of problems to overcome in order to apply lithium metal as a negative electrode material of a secondary battery. First of all, unlike the graphite-based negative electrode material, the lithium metal negative electrode, unlike the graphite-based negative electrode material, is converted into neutral lithium through electrochemical reaction with electrons passing from the external conductor. The mass is easily formed into a dendritic shape. The non-uniform surface thus formed provides an overall expanded volume, and during discharge, lithium is more likely to dissociate directly from the lithium metal without selectively falling off from the lithium resin phase. The metal cathode surface not only causes very extreme volume changes, but also results in irregular and complex morphologies of the formed dendrite. This complex aspect of the surface is not stabilized at all as the cycle progresses, resulting in a very irregular cycle life with continuous generation and decay. In addition, the lithium dendritic phase formed during discharge dissociates to the electrolyte region as a whole, and the dendritic phase continues to grow in the vertical direction to penetrate the separator and directly or indirectly contact the anode surface positioned on the opposite side to cause a short circuit.

Therefore, in order to commercialize the lithium metal secondary battery, a situation in which a method of improving the charge and discharge characteristics of the lithium metal negative electrode and improving the life characteristics is required.

The present invention has been made in order to solve the problems of the prior art, a specific surface area and a current density distribution can be implemented uniformly to provide a negative electrode for a lithium metal secondary battery having excellent life characteristics and less irregular dendritic formation on the surface For the purpose of

Another object of the present invention is to provide a lithium metal secondary battery having excellent charge and discharge characteristics by including the electrode.

In order to solve the above problems, the present invention is a current collector; And a polymer layer formed on at least one surface of the current collector, wherein the polymer layers are arranged in a lattice structure with empty spaces, and the empty spaces are filled with lithium. do.

In addition, the present invention comprises the steps of filling the lithium polymer layer consisting of a lattice structure (step 1); And forming a lithium-filled polymer layer on at least one surface of a current collector (step 2).

In addition, the present invention is the negative electrode; anode; A separator disposed between the cathode and the anode; And it provides a lithium metal secondary battery comprising an electrolyte.

The negative electrode according to the present invention includes a polymer layer arranged in a lattice structure with an empty space, so that the specific surface area of the negative electrode can be increased, and the current density distribution can be uniformly implemented, thereby providing excellent life characteristics and irregular dendritic formation. Can be suppressed.

In addition, since the lithium metal secondary battery according to the present invention includes the negative electrode, charging and discharging efficiency may be increased by lithium filled in the empty space of the polymer layer, and thus life characteristics may be improved.

Therefore, the negative electrode and the lithium metal secondary battery including the same according to the present invention can be usefully applied to the battery industry.

The following drawings, which are attached to this specification, illustrate exemplary embodiments of the present invention, and together with the contents of the present invention serve to further understand the technical idea of the present invention, the present invention is limited to the matters described in such drawings. It should not be construed as limited.

FIG. 1 schematically shows the structure of a negative electrode 100 according to an embodiment of the present invention, and FIG. 1A schematically shows one cross section of the negative electrode 100 (filled with lithium). 1B schematically shows a plan view of the cathode 100 (not shown in which an empty space is filled with lithium).

FIG. 2 is an SEM image of the dendritic shape formed on the negative electrode of the coin-shaped half cell of Example 1 according to an embodiment of the present invention after charging and discharging, wherein (a) is measured at a magnification X2,000. (b) is measured at magnification X5,000.

3 is a SEM image of the dendritic shape formed on the negative electrode after charge and discharge of the coin-type half-cell of Comparative Example 3 according to an embodiment of the present invention, (a) is measured at a magnification X2,000. (b) is measured at magnification X5,000.

[Description of the code]

100: cathode

10: whole house

20: polymer layer

21, 22: lattice structure

P: empty space

L: lithium

Hereinafter, the present invention will be described in more detail to aid in understanding the present invention.

The terms or words used in this specification and claims are not to be construed as limiting in their usual or dictionary meanings, and the inventors may appropriately define the concept of terms in order to best describe their invention. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that the present invention.

The present invention can be uniformly implemented in the current density distribution, to provide a negative electrode for a lithium metal secondary battery that can improve the charge and discharge efficiency and life characteristics of the lithium metal secondary battery comprising the same.

The negative electrode for a lithium metal secondary battery according to an embodiment of the present invention is a current collector; And a polymer layer formed on at least one surface of the current collector, wherein the polymer layer is arranged in a lattice structure with an empty space, and the empty space is filled with lithium.

Hereinafter, the electrode according to an exemplary embodiment of the present invention will be described in detail with reference to FIG. 1.

FIG. 1 schematically shows the structure of a negative electrode according to an embodiment of the present invention, FIG. 1A schematically shows a cross section of the negative electrode, and FIG. 1B schematically shows a plan view of the negative electrode. .

As shown in Figure 1, the negative electrode 100 according to an embodiment of the present invention is a current collector (10); And a polymer layer 20, wherein the polymer layer 20 is arranged in a lattice structure 21, 22 with an empty space P, and the empty space P is filled with lithium (L). It may be.

The current collector 10 is not particularly limited as long as it has high conductivity without causing chemical change in the battery. For example, the current collector 10 may be formed on a surface of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel. And surface-treated with carbon, nickel, titanium, silver, or the like. Specifically, the current collector 10 may be copper.

In addition, the current collector 10 may be one having a thickness of typically 3 ㎛ to 500 ㎛.

The polymer layer 20 is positioned on at least one surface of the current collector 10 and has a lattice structure. For example, the polymer layer 20 may have a mesh structure.

Specifically, the polymer layer 20 may be formed in a lattice structure as described above, the lattice structure may be arranged with an empty space (P). In this case, the lattice structure is arranged at a predetermined interval, and thus the empty space P in the polymer layer 20 may have a predetermined size.

In addition, the empty space P may occupy an area of 40% to 60% of the total area of the polymer layer 20, and specifically, may occupy an area of 50%. That is, the open area of the polymer layer 20 may be 40% to 60%.

In the negative electrode according to the embodiment of the present invention, the polymer layer has a mesh structure and the above-described empty space may increase the specific surface area of the negative electrode including the same, thereby providing a uniform current density distribution. Charging of lithium ions transferred from the positive electrode during charging of the lithium metal secondary battery may be easy. In addition, the polymer layer may serve as a protective layer to block direct contact with the electrolyte.

In addition, the negative electrode 100 according to an embodiment of the present invention may be a lithium (L) is filled in the empty space (P) as described above, specifically, the lithium (L) is a polymer layer The empty space P may be filled to cover an area of 5% to 20% of the total area. Specifically, it may be filled to cover an area of 5% to 10%. If the lithium (L) is filled in the above range, it is possible to improve the electrochemical charge and discharge reversibility without significantly reducing the pore and specific surface area of the polymer layer.

Here, the lithium (L) may be filled in the empty space (P) by the manufacturing method described below, wherein the lithium (L) is located in the empty space (P) between the lattice structure and the polymer layer It may be attached to.

Meanwhile, the polymer layer 20 may have a thickness of 10 μm to 100 μm. Specifically, it may have a thickness of 20 μm to 50 μm.

In addition, the polymer layer may be made of nylon, the lattice width of the lattice structure may be 1 ㎛ to 10 ㎛. Specifically, the lattice width of the lattice structure may be 2 ㎛ to 5 ㎛. If the lattice width of the lattice structure is out of the range, the size of the empty space P formed by the lattice structure may be too large or small, and as a result, when charging and discharging a lithium metal secondary battery using the negative electrode including the same, Lithium ion migration may not be smooth.

In addition, the present invention provides a method for producing a negative electrode for a lithium metal secondary battery.

The manufacturing method according to an embodiment of the present invention comprises the steps of filling the lithium polymer layer consisting of a lattice structure (step 1); And forming a lithium-filled polymer layer on at least one surface of a current collector (step 2).

Step 1 is a step for manufacturing a lithium-filled polymer layer, it may be performed by applying a current after manufacturing a coin-type half-cell using a lithium source and a polymer for providing lithium.

Specifically, Step 1 is performed by applying a current of 0.5 mA to 1 mA after producing a coin-type half-cell through a separator and an electrolyte between the lithium thin film and the polymer using a lithium thin film as a positive electrode, a polymer as a negative electrode. It may be. At this time, lithium is transferred from the lithium thin film to the polymer may be filled in the empty space between the lattice structure in the polymer.

In this case, the polymer may be manufactured and used to have a desired empty space by arranging nylon wires in a lattice structure, or may be used by purchasing a commercially available nylon mesh (nylon mesh).

Step 2 is a step for manufacturing a negative electrode for a lithium metal secondary battery including a polymer layer made of a lattice structure, it may be performed by placing and attaching the lithium-filled polymer layer on at least one surface of the current collector.

In addition, the present invention provides a lithium metal secondary battery including the negative electrode.

The lithium metal secondary battery according to an embodiment of the present invention the negative electrode; anode; A separator disposed between the cathode and the anode; And an electrolyte.

The positive electrode is not particularly limited, but may be a lithium thin film or a positive electrode active material layer formed on one surface of a current collector. If the positive electrode is a positive electrode active material layer formed on one surface of the current collector, the positive electrode may be prepared by applying a positive electrode active material slurry containing a positive electrode active material on one surface of the current collector and then drying it. The slurry may further include additives such as a binder and a conductive material, a filler, and a dispersant in addition to the positive electrode active material.

The positive electrode active material is not particularly limited, but may be, for example, a manganese spinel active material, a lithium metal oxide, or a mixture thereof, and the lithium metal oxide may be lithium-manganese oxide, lithium-nickel-manganese oxide, lithium Manganese cobalt-based oxides and lithium-nickel-manganese-cobalt-based oxides. Specifically, the positive electrode active material is LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , Li (Ni _a Co _b Mn _c ) O ₂ (where 0 <a <1, 0 <b <1, 0 < c <1, a + b + c = 1), LiNi _1-y Co _y O ₂ , LiCo _1-y Mn _y O ₂ , LiNi _1-y Mn _y O ₂ (where 0 ≦ y <1), Li (Ni _d Co _e Mn _f ) O ₄ (where 0 <d <2, 0 <e <2, 0 <f <2, d + e + f = 2), LiMn _2-z Ni _z O ₄ , LiMn _2-z Co ₂ O ₄ , where 0 <z <2.

The binder is a component that assists the bonding between the positive electrode active material and the conductive material and the current collector, and may generally be added in an amount of 1 wt% to 30 wt% based on the total amount of the positive electrode active material slurry. Such binders are not particularly limited but include, for example, vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate. Polymethylmethacrylate, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene- It may be one, or a mixture of two or more selected from the group consisting of diene monomer (EPDM), sulfonated EPDM, styrene-butyrene rubber (SBR) and fluorine rubber.

The conductive material is not particularly limited, but for example, graphite such as natural graphite or artificial graphite; Carbon blacks such as carbon black (super-p), acetylene black, ketjen black, channel black, furnace black, lamp black and thermal black; Conductive fibers such as carbon fibers and metal fibers; Metal powders such as carbon fluoride powder, aluminum powder 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. The conductive material may typically be in an amount of 0.05 wt% to 5 wt% based on the total weight of the cathode active material slurry.

The filler may be used as necessary to determine whether or not to be used as a component for inhibiting the expansion of the positive electrode, and if the fibrous material without causing chemical changes in the battery is not particularly limited, for example, olefin polymers such as polyethylene polypropylene; It may be a fibrous material such as glass fiber, carbon fiber.

The dispersant (dispersion) is not particularly limited, but may be, for example, isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or the like.

The coating may be performed by a method commonly known in the art, but for example, the positive electrode active material slurry may be distributed on an upper surface of one side of the positive electrode current collector, and then uniformly dispersed using a doctor blade or the like. Can be. In addition, the method may be performed by a die casting method, a comma coating method, a screen printing method, or the like.

The drying is not particularly limited, but may be performed within one day in a vacuum oven at 50 ℃ to 200 ℃.

The separator may be an insulating thin film having high ion permeability and mechanical strength, and may generally have a pore diameter of 0.01 μm to 10 μm and a thickness of 5 μm to 300 μm. As such a separator, a porous polymer film, such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, or the like, is made of a porous polymer film alone. Or these can be laminated | stacked and used. In addition, a conventional porous nonwoven fabric, for example, a non-woven fabric made of glass fibers, polyethylene terephthalate fibers and the like of high melting point may be used, but is not limited thereto.

The electrolyte may include an organic solvent and a lithium salt commonly used in the electrolyte, and are not particularly limited.

With the lithium salt of the anion is ^{F -, Cl -, 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 SO 2) 2 N -, (FSO 2 _{^{) 2 N -, CF 3 CF}} 2 (CF 3) 2 CO -, (CF 3 CO 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 - may be at least one member selected from the group consisting of ^- and _{(CF 3 CF 2 SO 2)} 2 N.

Typical organic solvents include propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, methylpropyl carbonate, dipropyl carbonate, dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane and vinylene. It may be one or more selected from the group consisting of carbonate, sulfolane, gamma-butyrolactone, propylene sulfide and tetrahydrofuran.

In particular, ethylene carbonate and propylene carbonate, which are cyclic carbonates among the carbonate-based organic solvents, may be preferable because of high dielectric constant and high dissociation of lithium salts in the electrolyte, and dimethyl carbonate and diethyl carbonate in such cyclic carbonates. By using a low viscosity, low dielectric constant linear carbonate, such as mixed in an appropriate ratio it can be more preferably used to make an electrolyte having a high electrical conductivity.

In addition, the electrolyte may be pyridine, triethyl phosphate, triethanolamine, cyclic ether, ethylene diamine, n-glyme, hexaphosphate triamide, nitrobenzene derivative, if necessary, in order to improve charge and discharge characteristics and flame retardancy characteristics. , Sulfur, quinone imine dye, N-substituted oxazolidinone, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxy ethanol, aluminum trichloride, and the like. . In some cases, the solvent may further include a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride to impart nonflammability, may further include carbon dioxide gas to improve high temperature storage characteristics, and may further include fluoro-ethylene carbonate. ), PRS (propene sultone), FPC (fluoro-propylene carbonate) may further include.

In the lithium metal secondary battery of the present invention, an electrode assembly is formed by disposing a separator between a positive electrode and a negative electrode, and the electrode assembly may be prepared by putting an electrolyte into a cylindrical battery case or a square battery case. Alternatively, after stacking the electrode assembly, it may be prepared by impregnating it in an electrolyte and sealing the resultant obtained in a battery case.

The battery case may be adopted that is commonly used in the art, there is no limitation on the appearance according to the use of the battery, for example, cylindrical, square, pouch (coin) type or coin (coin) using a can, etc. This can be

The lithium secondary battery according to the present invention may not only be used in a battery cell used as a power source for a small device, but also preferably used as a unit battery in a medium-large battery module including a plurality of battery cells. Preferred examples of the medium-to-large device include, but are not limited to, electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, power storage systems, and the like.

EMBODIMENT OF THE INVENTION Hereinafter, an Example is given and it demonstrates in detail in order to demonstrate this invention concretely. However, embodiments according to the present invention can be modified in many different forms, the scope of the present invention should not be construed as limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

Example 1

1) Preparation of Cathode

1M LiPF ₆ is added to a solvent in which a polyolefin separator is interposed between the lithium thin film and the polymer with a lithium thin film having a thickness of 150 μm as a positive electrode and a nylon mesh as a negative electrode. A coin-type half cell was prepared by injecting the dissolved electrolyte solution. Then, a lithium mesh-filled nylon mesh was prepared by applying a current of 0.5 mA to the cell. In this case, the nylon mesh was formed in a lattice structure with a blank space, the void space was 50% of the total area of the nylon mesh, the thickness is 50 ㎛ and the grid width was 5 ㎛. In addition, lithium was charged at a rate of 10% of the total area of the nylon mesh void space.

The prepared lithium-filled nylon mesh was bonded to a 20 μm thick copper thin film to prepare a negative electrode.

2) Lithium metal secondary battery manufacturing

The prepared negative electrode was used as a working electrode, and a lithium thin film having a thickness of 150 μm was used as a positive electrode. After interposing the polyolefin separator between the negative electrode and the positive electrode, an electrolyte solution in which 1M LiPF ₆ was dissolved was injected into a solvent in which ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 50:50, thereby preparing a coin-type half cell.

Example 2

1) Preparation of Cathode

1M LiPF ₆ is added to a solvent in which a polyolefin separator is interposed between the lithium thin film and the polymer with a lithium thin film having a thickness of 150 μm as a positive electrode and a nylon mesh as a negative electrode. A coin-type half cell was prepared by injecting the dissolved electrolyte solution. Then, a lithium mesh-filled nylon mesh was prepared by applying a current of 0.5 mA to the cell. In this case, the nylon mesh is formed in a lattice structure with a blank space, the void space was 50% of the total area of the nylon mesh, the thickness is 50 ㎛, the grid width was 2 ㎛. In addition, lithium was charged at a rate of 10% of the total area of the nylon mesh void space.

The prepared lithium-filled nylon mesh was bonded to a 20 μm thick copper thin film to prepare a negative electrode.

2) Lithium metal secondary battery manufacturing

The prepared negative electrode was used as a working electrode, and a lithium thin film having a thickness of 150 μm was used as a positive electrode. After interposing the polyolefin separator between the negative electrode and the positive electrode, an electrolyte solution in which 1M LiPF ₆ was dissolved was injected into a solvent in which ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 50:50, thereby preparing a coin-type half cell.

Example 3

1) Preparation of Cathode

1M LiPF ₆ is added to a solvent in which a polyolefin separator is interposed between the lithium thin film and the polymer with a lithium thin film having a thickness of 150 μm as a positive electrode and a nylon mesh as a negative electrode. A coin-type half cell was prepared by injecting the dissolved electrolyte solution. Then, a lithium mesh-filled nylon mesh was prepared by applying a current of 0.5 mA to the cell. In this case, the nylon mesh is formed in a lattice structure with a blank space, the void space was 50% of the total area of the nylon mesh, the thickness is 50 ㎛, the grid width was 5 ㎛. In addition, lithium was filled at a rate of 5% of the total area of the nylon mesh void space.

The prepared lithium-filled nylon mesh was bonded to a 20 μm thick copper thin film to prepare a negative electrode.

2) Lithium metal secondary battery manufacturing

The prepared negative electrode was used as a working electrode, and a lithium thin film having a thickness of 150 μm was used as a positive electrode. After interposing the polyolefin separator between the negative electrode and the positive electrode, an electrolyte solution in which 1M LiPF ₆ was dissolved was injected into a solvent in which ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 50:50, thereby preparing a coin-type half cell.

Example 4

1) Preparation of Cathode

1M LiPF ₆ is added to a solvent in which a polyolefin separator is interposed between the lithium thin film and the polymer with a lithium thin film having a thickness of 150 μm as a positive electrode and a nylon mesh as a negative electrode. A coin-type half cell was prepared by injecting the dissolved electrolyte solution. Then, a lithium mesh-filled nylon mesh was prepared by applying a current of 0.5 mA to the cell. In this case, the nylon mesh is formed in a lattice structure with a blank space, the void space was 50% of the total area of the nylon mesh, the thickness is 50 ㎛, the grid width was 5 ㎛, lithium is a nylon mesh It is filled at 25% of the total space.

The prepared lithium-filled nylon mesh was bonded to a 20 μm thick copper thin film to prepare a negative electrode.

2) Lithium metal secondary battery manufacturing

The prepared negative electrode was used as a working electrode, and a lithium thin film having a thickness of 150 μm was used as a positive electrode. After interposing the polyolefin separator between the negative electrode and the positive electrode, an electrolyte solution in which 1M LiPF ₆ was dissolved was injected into a solvent in which ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 50:50, thereby preparing a coin-type half cell.

Example 5

1) Preparation of Cathode

1M LiPF ₆ is added to a solvent in which a polyolefin separator is interposed between the lithium thin film and the polymer with a lithium thin film having a thickness of 150 μm as a positive electrode and a nylon mesh as a negative electrode. A coin-type half cell was prepared by injecting the dissolved electrolyte solution. Then, a lithium mesh-filled nylon mesh was prepared by applying a current of 0.5 mA to the cell. In this case, the nylon mesh is formed in a lattice structure with a blank space, the void space was 50% of the total area of the nylon mesh, the thickness is 50 ㎛, the grid width was 5 ㎛, lithium is a nylon mesh It was filled at a rate of 3% of the total area of empty space.

The prepared lithium-filled nylon mesh was bonded to a 20 μm thick copper thin film to prepare a negative electrode.

2) Lithium metal secondary battery manufacturing

The prepared negative electrode was used as a working electrode, and a lithium thin film having a thickness of 150 μm was used as a positive electrode. After interposing the polyolefin separator between the negative electrode and the positive electrode, an electrolyte solution in which 1M LiPF ₆ was dissolved was injected into a solvent in which ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 50:50, thereby preparing a coin-type half cell.

Comparative Example 1

A copper thin film having a thickness of 20 μm was used as a cathode as a working electrode, and a lithium thin film having a thickness of 150 μm was used as a positive electrode as a counter electrode. After interposing the polyolefin separator between the negative electrode and the positive electrode, an electrolyte solution in which 1M LiPF ₆ was dissolved was injected into a solvent in which ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 50:50, thereby preparing a coin-type half cell.

Comparative Example 2

A current collector in which a nylon layer was formed on a copper thin film having a thickness of 20 μm was used as a working electrode as a cathode, and a lithium thin film having a thickness of 150 μm was used as a positive electrode as a counter electrode. In this case, the nylon layer used a nylon mesh formed in a lattice structure with a blank space of the nylon wire, the void space in the nylon mesh was 50% of the total area of the nylon layer, the thickness is 50 ㎛, the grid width is 5 [Mu] m.

After interposing the polyolefin separator between the negative electrode and the positive electrode, an electrolyte solution in which 1M LiPF ₆ was dissolved was injected into a solvent in which ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 50:50, thereby preparing a coin-type half cell.

Comparative Example 3

A current collector in which a nylon layer was formed on a copper thin film having a thickness of 20 μm was used as a working electrode as a cathode, and a lithium thin film having a thickness of 150 μm was used as a positive electrode as a counter electrode. In this case, the nylon layer used a nylon mesh formed in a lattice structure with a blank space of the nylon wire, the void space in the nylon mesh was 50% of the total area of the nylon layer, the thickness is 50 ㎛, the grid width is 5 [Mu] m. After interposing the polyolefin separator between the negative electrode and the positive electrode, an electrolyte solution in which 1M LiPF ₆ was dissolved was injected into a solvent in which ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 50:50, thereby preparing a coin-type half cell.

Experimental Example 1

Charge and discharge capacity characteristics of the batteries prepared in Examples 1, 2, and Comparative Examples 1 to 3 were charged and discharged using an electrochemical charger. The results are shown in Tables 1 and 2, Table 1 shows each cell charged at 1 mA / cm ² and Table 2 shows the results obtained by charging each cell at 2 mA / cm ² .

Specifically, each battery was charged at 1 mA / cm ² or 2 mA / cm ² from 1 hour to 2 hours and the voltage was 1 V vs. Discharge was performed until Li / Li ⁺ . That is, the charge capacity was fixed to a certain amount and the discharge capacity was given a voltage cut-off to obtain the discharge capacity value and the charge / discharge efficiency value.

division	Initial Charge Capacity (mAh)	50 cycles discharge capacity (mAh)	50 cycles charge / discharge capacity retention rate (%)
Example 1	3.99	3.82	95.74
Example 2	4.00	3.78	94.50
Example 3	3.98	3.80	95.50
Example 4	4.00	1.25	31.25
Example 5	3.96	1.36	34.3
Comparative Example 1	3.97	0.78	19.65
Comparative Example 2	4.03	0.96	23.82
Comparative Example 3	4.02	0.68	16.92

division	Initial Charge Capacity (mAh)	50 cycles discharge capacity (mAh)	50 cycles charge / discharge capacity retention rate (%)
Example 1	3.99	3.24	81.20
Example 2	4.00	3.15	78.75
Example 3	3.98	3.18	79.90
Example 4	4.00	1.06	26.50
Example 5	9.36	1.07	27.00
Comparative Example 1	3.97	0.15	3.78
Comparative Example 2	4.03	0.47	11.66
Comparative Example 3	4.02	0.32	7.96

As shown in Table 1 and Table 2, the battery of Examples 1 to 5 is significantly less charge and discharge capacity reduction rate compared to the batteries of Comparative Examples 1 to 3 under both charging conditions and excellent life characteristics It was confirmed.

Meanwhile, Examples 4 and 3, in which lithium is filled to cover an area of 5% to 20% of the total area of the polymer layer empty space, are filled in to cover 25% and 3%, respectively. It was confirmed that there was a markedly improved lifespan characteristic compared to Example 5. Through this, it was confirmed that more significant effects can be achieved by filling lithium in a specific ratio in the empty space of the polymer layer.

Experimental Example 2

After charging and discharging each lithium metal secondary battery prepared in Example 1 and Comparative Example 3, the battery was disassembled and the dendritic formation was observed by measuring SEM on the negative electrode surface, and the results are shown in FIGS. 2 and 3.

As shown in FIGS. 2 and 3, in the case of the negative electrode of Comparative Example 3, a sharp and thread-like resin phase was formed as a whole, whereas in the negative electrode of Example 1, a sharp and yarn-like dendritic phase was not observed. Did.

Claims (10)

1. Current collector; And

   A polymer layer formed on at least one surface of the current collector;

   The polymer layers are arranged in a lattice structure with empty spaces,

   Lithium is filled in the empty space lithium metal secondary battery negative electrode.
2. The method according to claim 1,

   The empty space is a lithium metal secondary battery negative electrode that occupies an area of 40% to 60% of the total area of the polymer layer.
3. The method according to claim 1,

   The lithium is a lithium metal secondary battery negative electrode that is filled to cover an area of 5% to 20% of the total area of the empty space of the polymer layer.
4.  The method according to claim 1,

   The polymer layer is a lithium metal secondary battery negative electrode made of nylon.
5. The method according to claim 1,

   The polymer layer is a lithium metal secondary battery negative electrode having a thickness of 10 ㎛ to 100 ㎛.
6. The method according to claim 1,

   The lattice width of the lattice structure is a negative electrode for a lithium metal secondary battery of 1 ㎛ to 10 ㎛.
7. 1) filling lithium into a lattice structure polymer layer; And

   2) A method of manufacturing a negative electrode for a lithium metal secondary battery according to claim 1, comprising forming the lithium-filled polymer layer on at least one surface of a current collector.
8. The method according to claim 7,

   The polymer layer is a method of manufacturing a negative electrode for a lithium metal secondary battery that is made of nylon.
9. The method according to claim 7,

   Step 1) is performed by applying a current of 0.5 mA to 1 mA after producing a coin-type half-cell through a separator and an electrolyte between the lithium thin film and the polymer using a lithium thin film as a positive electrode, a polymer as a negative electrode. Method of manufacturing a negative electrode for a lithium metal secondary battery.
10. A negative electrode according to claim 1; anode; A separator disposed between the cathode and the anode; And a lithium metal secondary battery comprising an electrolyte.

Images