KR100824048B1 - A negative electrode for a lithium battery, a manufacturing method thereof and a lithium battery employing the same - Google Patents

Abstract

The present invention relates to a negative electrode for a lithium battery, a manufacturing method thereof, and a lithium battery employing the same, and more specifically, a conductive substrate; And it relates to a negative electrode for a lithium battery comprising a lithium metal dispersion electrodeposition layer formed on one surface of the conductive substrate, a manufacturing method and a lithium battery employing the same.

According to the present invention, dissolution and deposition of charge and discharge of lithium ions by dispersing and depositing lithium metal on a metal substrate using a lithium metal dispersion electrodeposition layer comprising a non-conductive polymer layer or a non-conductive oxide layer. ), A negative electrode for a lithium battery which ensures that the electrode is generated evenly over the entire surface of the electrode, and consequently suppresses the formation of pitch and dendrite on the surface of the electrode, thereby improving the reversible capacitance of the lithium battery, and a method of manufacturing the same. And a lithium battery employing the same.

Description

An anode for a lithium battery, a manufacturing method and a lithium battery employing the same {An anode for lithium battery, a method for preparing the anode and a lithium battery employing the same}

1A and 1B perform 0, 50, and 100 charge / discharge cycles (1 mAcm ⁻² , 1 Ccm ⁻² ) on the lithium metal negative electrode 1a and the lithium metal negative electrode 1b in the form of a thin film, respectively. Scanning electron micrographs showing the phenomenon that the dendritic phase is formed on the electrode surface afterwards.

2 is a schematic perspective view of a negative electrode for a lithium battery according to the present invention.

3A to 3B are schematic perspective views of a negative electrode for a lithium battery according to the present invention, respectively, when the lithium metal layer pattern is formed of the stripe pattern 3a and the amorphous pattern 3b.

4a to 4d illustrate a schematic view of an electrode stack structure according to a process in the method of manufacturing a negative electrode for a lithium battery according to the present invention.

<Short description of drawing symbols>

21, 41: conductive substrate

22a, 42a: layer of non-conductive material

22b, 42b: lithium metal layer

The present invention relates to a negative electrode for a lithium battery, a method of manufacturing the same, and a lithium battery employing the same, and more particularly, to a lithium metal on a metal substrate using a lithium metal dispersion electrodeposition layer including a non-conductive polymer layer or a non-conductive oxide layer. Dispersing electrodepositing ensures that dissolution and deposition due to charge and discharge of lithium ions are generated evenly throughout the electrode surface, resulting in the formation of pitch and dendrite at the electrode surface. The present invention relates to a negative electrode for a lithium battery, a method of manufacturing the same, and a lithium battery employing the same.

Lithium battery is a generic term for a battery using a lithium metal or a lithium compound as a negative electrode, lithium batteries employing a variety of materials as a negative electrode has a high voltage and high energy density characteristics, many studies have been made in the past. Among them, lithium metal has a very good battery capacity, and when replacing the negative electrode (having a structure in which lithium is present in an ion state in the carbon electrode) of a commercially available lithium battery with lithium metal, the capacity of the battery is 10 times or more based on the negative electrode. This is known to increase.

In the early stages of the development of lithium batteries, lithium metal was attracting attention as a negative electrode material. However, when lithium metal itself is used as a negative electrode, a dendrite is formed on the surface of the lithium metal as the charge and discharge cycle proceeds, and reaction with the electrolyte is performed. There is a problem in that the charge and discharge efficiency or the electric capacity is lowered and a short circuit with the positive electrode is caused, and the lithium metal itself has a very high reactivity.

The mechanism of dendritic formation is as follows. In other words, when lithium metal in the form of a thin film is used as a cathode, during discharging, lithium ions are not uniformly dissolved throughout the surface of the cathode, but local dissolution occurs to generate holes or pitches in the surface of the cathode. At the time of charging, the dissolved lithium ions are not returned to their original dissolved sites but are deposited only to a specific portion, thereby forming a resinous phase. The formation of the dendritic phase is more severe when the lithium metal in the form of a thin film is used as the negative electrode rather than the lithium metal in the form of powder. Scanning electron micrographs showing the phenomenon of dendritic formation on the electrode surface after 50 and 100 charge and discharge (1 mAcm ⁻² , 1 Ccm ⁻² ) were shown. On the other hand, when the electrolyte and the lithium metal are in direct contact, both react to form a solid electrolyte interface (SEI), thereby promoting irreversible lithium loss.

Therefore, in order to solve the above problems, a technique for suppressing expansion and contraction due to charging and discharging using a carbon-based material as a cathode material has also been proposed (Japanese Patent Laid-Open Nos. 199-286763 and 1998-003920, etc.). ), This also has a problem that the capacity is lowered and the initial charge and discharge efficiency is lower than when using a lithium metal or a lithium alloy.

In addition, since alloys such as lithium, lithium-aluminum, lithium-lead, lithium-tin, and lithium-silicon are known to have a larger capacitance than carbon-based materials, there have been attempts to employ such alloys as negative electrode materials. In addition, when such alloys or metals are used alone, problems such as precipitation of dendritic lithium and sudden volume changes may occur, so that they have to be properly mixed with carbon-based materials.

Therefore, in order to solve the problems of the prior art, the charge and discharge of lithium ions by dispersing electrodepositing lithium metal on a metal substrate using a lithium metal dispersion electrodeposition layer comprising a non-conductive polymer layer or a non-conductive oxide layer. To ensure that dissolution and deposition are evenly generated across the electrode surface, and consequently to suppress the formation of pitch and dendrite on the electrode surface, thereby reversible capacitance of the lithium battery An object of the present invention is to provide a negative electrode for a lithium battery, a method for manufacturing the same, and a lithium battery employing the same.

The present invention to achieve the above technical problem,

Conductive substrates; And

Provided is a negative electrode for a lithium battery including a lithium metal dispersion electrode layer laminated on one surface of the conductive substrate.

According to a preferred embodiment of the present invention, the lithium metal dispersion electrodeposition layer includes a lithium metal layer pattern in the non-conductive polymer layer or the non-conductive oxide layer.

According to a preferred embodiment of the present invention, the lithium metal layer pattern is a dot pattern, a stripe pattern or an amorphous pattern.

According to a preferred embodiment of the present invention, the average diameter of the dots is 20nm to 5㎛, the width of the stripe is 100nm to 5㎛.

According to a preferred embodiment of the present invention, the surface area of the lithium metal layer pattern accounts for 5 to 60 area% of the total surface area of the lithium metal dispersion electrodeposition layer.

The present invention to achieve the above other technical problem,

Stacking a non-conductive material layer on one surface of the conductive substrate;

Forming a pattern on the non-conductive material layer to expose a portion of the conductive substrate; And

It provides a method for producing a negative electrode for a lithium battery comprising the step of electrodepositing a lithium metal layer on the exposed conductive substrate.

According to a preferred embodiment of the present invention, the nonconductive material is a nonconductive polymer or a nonconductive oxide.

According to a preferred embodiment of the present invention, the pattern is a dot pattern, a stripe pattern or an irregular pattern.

According to a preferred embodiment of the present invention, the average diameter of the dots is 20nm to 5㎛, the width of the stripe is 100nm to 5㎛.

According to a preferred embodiment of the present invention, the surface area of the pattern accounts for 5 to 60 area% of the total surface area of the non-conductive material layer.

According to a preferred embodiment of the present invention, the thickness of the non-conductive material layer is 100nm to 300nm.

According to a preferred embodiment of the present invention, the formation of the pattern is carried out by nanoimprinting, etching or scratching.

According to a preferred embodiment of the present invention, the electrodeposition of the lithium metal layer is a gas reaction method, thermal vapor deposition method, sputtering method, chemical vapor deposition method, plasma treatment chemical vapor deposition method, laser treatment chemical vapor deposition method, ion plating method, cathode arc treatment method, Or by jet vapor deposition.

In addition, the present invention to achieve the above another technical problem,

The lithium battery which employ | adopted the said negative electrode for lithium batteries is provided.

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

According to the present invention, by using the lithium metal dispersion electrodeposition layer, it is possible to suppress the generation of pitch and dendrite on the negative electrode surface of the lithium battery, and consequently to improve the reversible capacitance of the lithium battery. .

Thus, the lithium battery negative electrode according to the present invention, a conductive substrate; And a lithium metal dispersion electrode layer laminated on one surface of the conductive substrate.

2 is a schematic perspective view of a negative electrode for a lithium battery according to the present invention. Referring to FIG. 2, the lithium battery negative electrode according to the present invention is a lithium metal dispersion electrodeposition layer on one surface of a conductive substrate or a current collector 21. 22 has the structure shown.

The lithium metal dispersion electrodeposition layer 22 is formed of a pattern of the lithium metal layer 22b in the non-conductive material layer 22a. The surface area of the lithium metal participating in the electrode reaction by this structure is a thin film of lithium metal. It is reduced compared to the case of employing a. That is, as described above, when using a lithium metal in the form of a thin film as a negative electrode, the formation of pitch and dendrite generated during charging and discharging causes problems such as reversible reduction of the lithium battery capacity. .

This dendritic formation phenomenon is more severe in the lithium metal negative electrode in the form of a thin film than the lithium metal negative electrode in the powder form, it is determined that the battery reaction occurs only in a specific portion compared to the thin film form in the powder form. Therefore, it is preferable to employ a powder-type negative electrode in terms of suppressing dendritic formation, but the negative electrode in powder form also has a disadvantage in that dendritic formation proceeds when the number of charge and discharge cycles increases.

Therefore, the present invention focuses on the excellent physical properties of such a powder form compared to the thin film form, and restricts the formation of the dendritic phase by limiting the electrode surface participating in the electrode reaction of the lithium battery to a predetermined region using a non-conductive material. An anode for a lithium battery is provided. In particular, the negative electrode for a lithium battery according to the present invention has more excellent dendritic formation inhibiting effect than the powder type negative electrode and can be manufactured by a simple and economical method, and thus has an excellent effect compared to the conventional powder type negative electrode. .

The lithium metal dispersion electrodeposition layer 22 may be completed by forming a pattern of the lithium metal layer 22b in the non-conductive material layer 22a,

The non-conductive material layer 22a may be a non-conductive polymer layer or a non-conductive oxide layer, but is not limited thereto. The non-conductive polymer may include a polybenzyl acrylate-based polymer and a track-etched polymer membrane. polymer membrane), self-assembled diblock copolymer templates, and the like. Examples of the non-conductive oxide include anodized aluminum oxide (AAO) and the like. Can be mentioned.

The lithium metal layer pattern may be formed in a dot pattern as shown in FIG. 2, but may be formed in various patterns such as a stripe pattern as shown in FIG. 3A or an irregular pattern as shown in FIG. 3B. For example, when forming a pattern of the lithium metal layer in a dot pattern, the average diameter of the dot may be 20nm to 5㎛, when forming a pattern of the lithium metal layer in a stripe pattern, the width of the stripe is 100nm to 5 May be μm.

The surface area of the lithium metal layer to the total surface area of the lithium metal dispersion electrodeposited layer, which adds the surface areas of the non-conductive material layer and the lithium metal layer, is preferably 5 to 60 area%, in which case the surface area of the lithium metal layer is out of the above range. It is not preferable because of the manufacturing problems caused by the constraints.

On the other hand, the present invention, the step of laminating a non-conductive material layer on one surface of the conductive substrate; Forming a pattern on the non-conductive material layer to expose a portion of the conductive substrate; And it provides a method for producing a negative electrode for a lithium battery comprising the step of electrodepositing a lithium metal layer on the exposed conductive substrate.

4A to 4D illustrate schematic views of an electrode stack structure according to a process in the method of manufacturing a negative electrode for a lithium battery according to the present invention.

4A to 4D, in the method of manufacturing a negative electrode for a lithium battery according to the present invention, first, a conductive substrate 41 is prepared (FIG. 4A), and then a non-conductive material layer 42a is laminated on the conductive substrate. (FIG. 4B).

On the other hand, the thickness of the non-conductive material layer is preferably 100nm to 300nm, when the thickness exceeds 300nm, the ratio of the dot depth to the size of the dot pattern becomes large (deposition) of lithium There is a problem that this is not done properly, and if the thickness of the laminate is less than 100 nm, there is a problem that it is difficult to manufacture due to the constraint of the device is not preferable.

After the stacking of the non-conductive material layer 42a, a pattern is formed on the non-conductive material layer 42a to expose a portion of the conductive substrate (FIG. 4C). The pattern forming step is performed by, but not limited to, nanoimprinting, etching or scratching.

Finally, the electrode for lithium battery according to the present invention can be manufactured by performing the step (FIG. 4D) of electrodepositing the lithium metal layer 42b on the conductive substrate partially exposed by pattern formation. This is possible because the electrodeposition of lithium metal is selectively made only on the conductive substrate, not on the non-conductive material layer.

As a method for electrodeposition of lithium metal, methods such as gas reaction method, thermal vapor deposition method, sputtering method, chemical vapor deposition method, plasma treatment chemical vapor deposition method, laser treatment chemical vapor deposition method, ion plating method, cathode arc treatment method, or jet vapor deposition method, etc. For example.

Moreover, this invention provides the lithium battery which employ | adopted the said negative electrode for lithium batteries.

The lithium battery according to the present invention may be manufactured as follows by employing a negative electrode for a lithium battery including a conductive substrate and a lithium metal dispersion electrode layer laminated on one surface of the conductive substrate.

First, a cathode active material, a conductive material, a binder, and a solvent are mixed to prepare a cathode active material composition, and then the cathode active material composition is directly coated and dried on a conductive substrate, that is, a metal current collector, to prepare a cathode plate, or the cathode active material The composition may be cast on a separate support, and then a film obtained by peeling from the support may be laminated on a metal current collector to prepare a positive electrode plate.

As the cathode active material, lithium-containing metal oxides, all commonly used in the art may be used, for example, LiCoO ₂ , LiMn _x O _2x , LiNi _{1 - x} MnO _2x (x is 1 or 2), Ni _{1 -x- y Co x Mn y O} 2 (0≤x≤0.5, 0≤y≤0.5) and the like, than the volume of the sphere is _{LiMn 2 O 4, LiCoO 2,} LiNiO 2, LiFeO 2, V Examples of compounds capable of redox, such as ₂ O ₅ , TiS or MoS, can be given.

Carbon black may be used as the conductive material, and vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate, polytetrafluoroethylene and the like A mixture, a styrene butadiene rubber-based polymer may be used, and N-methylpyrrolidone, acetone, water and the like may be used as the solvent. At this time, the content of the positive electrode active material, the conductive material, the binder and the solvent may be determined within a range conventional in the art. In addition, as the conductive substrate, a surface treatment of carbon, nickel, titanium, silver, or the like may be used on the surface of stainless steel, nickel, copper, titanium or alloys thereof, copper or stainless steel, and the form thereof is a foil or a film. , Sheets, punched, porous or foams, and the like.

On the other hand, the separator is preferably a material having low resistance to the ion migration of the electrolyte and excellent in the ability to hydrate the electrolyte, specifically, materials such as glass fiber, polyester, Teflon, polyethylene, polypropylene or polytetrafluoroethylene are used. The form may be any form of nonwoven fabric or woven fabric.

Examples of the electrolyte include propylene carbonate, ethylene carbonate, diethyl carbonate, ethylmethyl carbonate, methylpropyl carbonate, butylene carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, and dioxo Column, 4-methyldioxolane, N, N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, dimethyl A solvent such as carbonate, methyl isopropyl carbonate, ethyl propyl carbonate, dipropyl carbonate, dibutyl carbonate, diethylene glycol or dimethyl ether or a mixed solvent thereof, such as LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiAlO ₄ , LiAlCl ₄ , LiN (C _x F _{2x +1} SO ₂ ) (C _y F _{2y +1} SO ₂ ), Group consisting of lithium salts such as LiCl and LiI From may be selected from a mixture of one or more electrolytes selected.

The separator is disposed between the positive electrode plate and the negative electrode plate as described above to form a battery structure, which is wound or folded, placed in a cylindrical battery case or a square battery case, and then injected with an organic electrolyte to complete the lithium battery according to the present invention. do.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are only for illustrating the present invention and are not intended to limit the scope of the present invention.

Example 1. Preparation of a negative electrode for a lithium battery according to the present invention

As a conductive substrate, NIP-K28 (manufactured by Chemoptics), a polybenzyl acrylate-based polymer, was coated on a stainless steel foil as a non-conductive material at a thickness of 200 nm. The non-conductive material layer was opposed to the coated substrate surface. Subsequently, a rubber plate was applied to the stamp and a pressure of 5 megapascals was applied to the rubber plate so that the dot pattern of the stamp was printed on the non-conductive material layer. The substrate on which the dot pattern was printed was cut to a size of 1 cm × 1 cm, and then a nickel current collector was connected thereto.

Meanwhile, the lithium foil is cut into a size of 1.5 cm x 1.5 cm, and then a nickel current collector terminal is connected thereto so that the stainless steel foil having the dot pattern is used as a working electrode, and the lithium foil is used as a counter electrode. After the half cells (electrodes) were assembled, they were assembled into beaker cells using 250cc glass bottles with plastic lids. At this time, the ratio of EC: DMC was 1: 1, and the electrolyte solution using 1M of LiClO ₄ as a salt was filled up to a height of 2 cm at the bottom of the glass bottle. A hole was then made between the plastic lids so that the electrical current collector protruded out of the vial and then sealed with a glue gun. At this time, in order to seal the electrical current collector, the lithium foil and the stainless steel foil having the dot pattern should be immersed in the electrolyte and kept in parallel with each other. Assembly of the cell was carried out in a glove box filled with argon gas.

The assembled beaker cell was connected to a battery cycler (One ATEC WBCS3000), and then a lithium electrodeposited on the conductive metal surface of a stainless steel foil having a dot pattern flowing a constant current of 1 mA / cm ² for 10 hours. It was carried out, and the lithium battery negative electrode according to the present invention was prepared by filling lithium between the dot pattern.

Example 2 Fabrication of Lithium Battery According to the Present Invention

The negative electrode for a lithium battery prepared according to Example 1 was taken out of the beaker cell and used as a negative electrode. In addition, a slurry prepared by mixing vanadium oxide (V ₂ O ₅ ) as an active material as a positive electrode, Ketjen black as a conductive material, and PVDF as a binder in a ratio of 85: 10: 5 was cast on an aluminum foil. As a separator, Celgard PP was used, and a solution in which 1M LiPF ₆ salt was dissolved in a mixed solvent consisting of Merck's EC: DMC: EMC = 1: 1: 1 was used as an electrolyte.

The separator was immersed in the electrolyte solution before cell assembly to sufficiently absorb the electrolyte solution, and the lithium cobalt oxide was cut into a size of 1 cm × 1 cm to attach an electrical current collector. In addition, the separator was cut | disconnected and used for 1.5 cm x 1.5 cm size. An aluminum lamination film was cut to a size of 3 cm × 3 cm, laminated between two aluminum lamination films in the order of a negative electrode, a separator, and a positive electrode, and sealed using a vacuum packaging machine to prepare a lithium battery according to the present invention.

According to the present invention, dissolution and deposition of charge and discharge of lithium ions by dispersing and depositing lithium metal on a metal substrate using a lithium metal dispersion electrodeposition layer comprising a non-conductive polymer layer or a non-conductive oxide layer. ), A negative electrode for a lithium battery that ensures that the electrode is generated evenly over the entire surface of the electrode, and consequently suppresses the formation of pitch and dendrite on the surface of the electrode, thereby improving the reversible electric capacity of the lithium battery, and its manufacture A method and a lithium battery employing the same can be provided.

Claims (14)

In the negative electrode for a lithium battery comprising a conductive substrate and a lithium metal dispersion electrode layer laminated on one surface of the conductive substrate, The lithium metal dispersion electrodeposition layer includes a lithium metal layer pattern, The surface area of the lithium metal layer pattern is a negative electrode for a lithium battery, characterized in that occupies 5 to 60 area% of the total surface area of the lithium metal dispersion electrodeposition layer. The negative electrode of claim 1, wherein the lithium metal layer pattern is formed in a non-conductive polymer layer or a non-conductive oxide layer. The negative electrode of claim 1, wherein the lithium metal layer pattern is a dot pattern, a stripe pattern, or an irregular pattern. The negative electrode of claim 3, wherein the dot has an average diameter of 20 nm to 5 μm, and the stripe has a width of 100 nm to 5 μm. delete Stacking a non-conductive material layer on one surface of the conductive substrate; Forming a pattern with a surface area of 5 to 60 area% relative to the total surface area of the non-conductive material layer to expose a portion of the conductive substrate; And Electrode manufacturing method of a negative electrode for a lithium battery comprising the step of electrodepositing a lithium metal layer on the exposed conductive substrate. The method of claim 6, wherein the nonconductive material is a nonconductive polymer or a nonconductive oxide. The method of claim 6, wherein the pattern is a dot pattern, a stripe pattern, or an irregular pattern. The method of claim 8, wherein the average diameter of the dots is 20 nm to 5 μm, and the width of the stripes is 100 nm to 5 μm. delete The method of claim 6, wherein the thickness of the non-conductive material layer is 100 nm to 300 nm. The method of claim 6, wherein the formation of the pattern is performed by nanoimprinting, etching, or scratching. The method of claim 6, wherein the electrodeposition of the lithium metal layer is a gas reaction method, thermal vapor deposition method, sputtering method, chemical vapor deposition method, plasma treatment chemical vapor deposition method, laser treatment chemical vapor deposition method, ion plating method, cathode arc treatment method, or jet vapor deposition method Method for producing a negative electrode for a lithium battery, characterized in that carried out by. The lithium battery which employ | adopted the negative electrode for lithium batteries as described in any one of Claims 1-4.

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