KR20190076769A - Lithium metal negative electrode, manufanturing method thereof and lithium metal battery including the same - Google Patents

Abstract

The present invention relates to a lithium metal negative electrode, a method for manufacturing the same, and a lithium secondary battery comprising the lithium metal negative electrode. The lithium metal negative electrode comprises: a current collector which is at least one of a current collector including a recess on at least one surface and a porous current collector including a void; a protective layer on at least one surface of the current collector; and a lithium metal layer including metal lithium positioned in the recess or the void of the current collector.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium metal cathode, a method of manufacturing the same, and a lithium secondary battery including the same. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

Embodiments of the present invention relate to a lithium metal cathode in which a lithium metal is located in a void or a concave portion of a current collector in which a protective layer is formed by using an electrodeposition process, a method for manufacturing the same, and a lithium secondary battery comprising the same.

2. Description of the Related Art [0002] In recent years, miniaturization and weight reduction of a battery used as a power source have been demanded due to the trend toward miniaturization and weight reduction of electronic products.

Lithium metal secondary batteries have recently been actively developed as a battery capable of charging and discharging at a high capacity with miniaturization and light weight.

 The lithium metal secondary battery uses lithium metal as the cathode. However, lithium metal reacts with moisture in the air with high reactivity of lithium to produce various by-products. Therefore, it is necessary to develop a technique for preventing the reaction of the lithium metal contained in the negative electrode in the process of manufacturing, storing, transporting, and assembling the lithium metal secondary battery and forming the electrode assembly in the case.

In general, a lithium metal secondary battery includes a positive electrode, a negative electrode, and an electrode assembly including a separator interposed between the positive electrode and the negative electrode. The electrode assembly has a structure in which an electrolyte is injected into the battery case. However, when a negative electrode containing a lithium metal is exposed to an electrolyte, it reacts with an electrolyte solution to form a product causing high resistance, thereby deteriorating the performance of the battery. In addition, lithium dendrites can grow on the surface of the cathode by the reaction between the lithium metal and the electrolytic solution, and internal short-circuiting occurs when the lithium dendrites penetrate the separation membrane.

Therefore, it is urgent to develop a lithium metal anode capable of improving safety without deteriorating the performance of a lithium metal secondary battery when it is applied to a battery at the same time as easy storage and transportation.

The present embodiments provide a lithium metal cathode capable of facilitating storage and transportation in the air during a process, improving structural stability and performance of a battery when employed in a lithium secondary battery, a method for producing the same, and a lithium secondary battery comprising the same I want to.

In one aspect, a lithium metal anode according to an embodiment includes a current collector, at least one of a current collector including a concave portion on at least one surface thereof and a porous current collector including a void, A protective layer, and a lithium metal layer including metallic lithium located in the recess or pore of the current collector.

In another aspect, a method of manufacturing a lithium metal anode according to an embodiment includes the steps of: preparing a current collector that is at least one of a current collector including a concave portion on at least one surface thereof and a porous current collector including a void; Forming a protective layer on at least one side of the protective layer, positioning a current collector on which the protective layer is formed in the plating liquid, and positioning a lithium source at a predetermined interval from the protective layer, And forming a lithium metal layer by applying a current between the source and the lithium metal in the recess or the cavity of the current collector.

In another aspect, a lithium secondary battery according to an embodiment includes a cathode, an anode, and an electrolyte, and the cathode may be a lithium metal cathode according to an embodiment.

Since the lithium metal anode according to the embodiments has lithium metal located in the concave portion or the pore of the current collector and the protective layer covering the current collector is located, it is possible to prevent the moisture and carbon dioxide in the air from reacting with the release metal at low cost .

 In addition, when the lithium metal anode according to the embodiments is applied to a lithium secondary battery, since it is not affected by the increase or decrease in the volume of lithium metal in the charging and discharging process, it is excellent in structural stability and the side reaction between the electrolyte and lithium metal is blocked. Performance can be improved.

FIGS. 1 to 4 schematically show cross sections of a lithium metal cathode according to an embodiment, respectively.
5 schematically shows a method of manufacturing a lithium metal anode according to an embodiment.
6A and 6B show the step of forming the lithium metal layer in more detail.
7 schematically shows a structure of a lithium secondary battery according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

In addition, since the sizes and thicknesses of the respective components shown in the drawings are arbitrarily shown for convenience of explanation, the present invention is not necessarily limited to those shown in the drawings.

Also, throughout the specification, when an element is referred to as "including" an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise.

In the drawings, the thickness is enlarged to clearly represent the layers and regions. Like parts are designated with like reference numerals throughout the specification. It will be understood that when an element such as a layer, film, region, plate, or the like is referred to as being "on" another portion, it includes not only the element directly over another element, Conversely, when a part is "directly over" another part, it means that there is no other part in the middle.

Hereinafter, the lithium metal cathode according to the embodiments will be described.

FIG. 1 schematically shows a lithium metal cathode 111 according to an embodiment.

Referring to FIG. 1, a lithium metal cathode 111 according to an embodiment may include a current collector 10, a protective layer 20, and a lithium metal layer 30.

Referring to FIG. 1, the current collector 10 includes a concave portion 10a on at least one surface thereof.

The horizontal cross-sectional area (xy plane) of the concave portion 10a may be 30% to 60%, more specifically 40% to 50% of the horizontal cross-sectional area of the current collector 10. When the horizontal cross-sectional area of the concave portion 10a is less than 30%, there is a problem that it is difficult to secure sufficient space for charging the lithium metal. If the horizontal cross-sectional area of the concave portion 10a exceeds 60%, the area of the opening is widened, and the area for supporting the protective layer 20 is reduced, thereby deteriorating the mechanical stability of the protective layer 20. [ Therefore, the horizontal cross-sectional area of the concave portion 10a preferably satisfies the above range.

The current collector 10 may be any metal that is stable in a voltage range of a lithium secondary battery to be applied. Specifically, for example, the current collector 10 may be made of at least one of copper, nickel, iron, chromium, zinc, stainless steel, and a mixture thereof.

The average thickness of the current collector 10 including the concave portion 10a on at least one surface thereof may be in the range of 30 占 퐉 to 100 占 퐉, more specifically, 50 占 퐉 to 70 占 퐉. When the average thickness of the current collector 10 is less than 30 탆, a sufficient amount of lithium metal can not be supported in the electrodeposition process, resulting in a problem that the energy density is lowered. If the thickness of the current collector 10 exceeds 100 mu m, the amount of lithium metal filled in the concave portion 10a of the current collector 10 is sufficient. However, since the diffusion distance of lithium ions increases, At the speed, the filled lithium can not be used again. Accordingly, there is a problem that the volume energy density is only reduced due to the increase of the thickness of the collector 10.

On the other hand, the protective layer 20 is located on at least one surface of the current collector 10 including at least one surface of the concave portion 10a.

The protective layer 20 may be made of a material having lithium ion conductivity and may be made of a material such as polyethylene oxide (PEO), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polyvinylidene fluoride (PVDF-co-HFP), LiPON, Li ₃ N, Li _x La _{1 - x} TiO ₃ (0 <x <1), Li ₂ S-GeS-Ga ₂ S ₃ , and mixtures thereof.

The average thickness of the protective layer 20 may be in the range of 0.01 탆 to 50 탆, more specifically in the range of 1 탆 to 10 탆. The thinner the thickness of the protective layer, the more favorable the output characteristics of the battery when the lithium metal anode according to this embodiment is applied to the lithium secondary battery. However, the lithium dendrite formed during charging / discharging of the battery can be prevented from being grown only if it is formed to a thickness exceeding a certain thickness. Therefore, when the thickness of the protective layer 20 satisfies the above range, the output characteristics of the battery can be improved and the growth of the lithium dendrite can be effectively blocked.

Next, the lithium metal layer 30 includes metallic lithium located in the concave portion 10a of the current collector 10.

At this time, the purity of the lithium metal contained in the lithium metal layer 30 may be 98% or more, more specifically 99.9% to 100%.

Meanwhile, the lithium metal layer 30 may be formed so that the lithium metal fills 40 to 60% by volume of the entire volume of the concave portion 10a of the current collector 10.

When the lithium metal layer 30 is formed in a form filled with lithium metal so as to exceed 60% by volume of the entire volume of the concave portion 10a, the lithium moved from the cathode active material enters the space and insufficient, thereby deteriorating the performance of the battery .

If the lithium metal layer 30 is filled with lithium metal so that the volume of the lithium metal layer 30 is less than 40% by volume of the total volume of the concave portion 10a, the performance of the battery employing the lithium metal negative electrode of the present embodiment is degraded.

Therefore, the lithium metal layer 30 is formed such that the lithium metal fills the volume of 40% by volume to 60% by volume of the entire volume of the concave portion 10a of the current collector 10, thereby realizing a lithium secondary battery having excellent performance .

In addition, when the content of the lithium metal contained in the lithium metal layer satisfies the above-described range, a protective layer (not shown) made of a material having lithium ion conductivity is formed on at least one surface of the current collector 10 including the concave portion 10a 20 are directly in contact with each other, it is possible to prevent peeling of the protective layer 20 from occurring during charging and discharging of the battery.

2 schematically shows a lithium metal anode according to another embodiment.

2, the lithium metal cathode 111 according to the present embodiment may include a current collector 10, a protective layer 20, and a lithium metal layer 30.

In the present embodiment, the current collector 10 includes a concave portion 10a on both sides.

The protective layer 20 may be positioned on both sides of the current collector 10 including the concave portion 10a.

1 except that recesses 10a are provided on both sides of the current collector 10 and the protective layer 20 is located on both surfaces of the current collector 10. In the present embodiment, And detailed description of other elements will be omitted.

3 schematically shows a lithium metal anode according to another embodiment.

3, the lithium metal cathode 111 according to the present embodiment may include a current collector 10, a protective layer 20, and a lithium metal layer 30.

In the present embodiment, the current collector 10 is a porous current collector including a cavity 10a.

The porosity of the porous current collector may be 20% to 80%, more specifically 30% to 50%. In addition, the average diameter of the voids included in the porous current collector may be in the range of 5 탆 to 500 탆, more specifically, in the range of 10 탆 to 100 탆 or 20 탆 to 30 탆. It is preferable that the porosity of the porous current collector and the average diameter of the pores satisfy the above range in order to form a protective layer excellent in mechanical stability.

On the other hand, the average thickness of the porous current collector including the voids may be 20 탆 to 200 탆, more specifically 50 탆 to 100 탆. If the average thickness of the current collector 10 is less than 20 占 퐉, a sufficient amount of metallic lithium can not be carried, so that the energy density can be lowered. If the average thickness of the current collector 10 exceeds 200 mu m, the amount of lithium metal in the pores is sufficient, but the diffusion distance of lithium ions increases, so that the charged lithium can not be used again at a charging / discharging rate higher than a certain level. Accordingly, there is a problem that the volume energy density is only reduced due to the increase of the thickness of the collector 10.

In this embodiment, the lithium metal layer 30 includes lithium metal located in the gap 10a.

At this time, the lithium metal layer 30 may be formed so that the lithium metal fills 40 to 60 volume% of the total volume of the gap 10a of the current collector 10. [

When the lithium metal layer 30 is formed in a form filled with lithium metal to exceed 60% by volume of the total volume of the voids 10a, the lithium moved from the cathode active material enters the space, resulting in a problem of deteriorating the performance of the battery.

If the lithium metal layer 30 is filled with lithium metal so that the volume of the lithium metal layer 30 is less than 40 vol% of the total volume of the void 10a, the performance of the battery employing the lithium metal negative electrode of the present embodiment is degraded.

Therefore, it is preferable that the lithium metal layer 30 is formed so that the lithium metal fills 40 to 60% by volume of the total volume of the pores 10a of the current collector 10 in order to realize a lithium secondary battery having excellent performance. .

On the other hand, a protective layer 20 is disposed on one side of the current collector 10 including the gap 10a.

1 except that the current collector 10 includes the void 10a and the lithium metal layer 30 in which the lithium metal is located is included in the gap 10a, The detailed description of other components will be omitted.

4 schematically shows a lithium metal anode according to another embodiment.

Referring to FIG. 4, the lithium metal cathode 111 according to the present embodiment may include a current collector 10, a protective layer 20, and a lithium metal layer 30.

In the present embodiment, the current collector 10 is a porous current collector including a cavity 10a.

The details of the porous collector are the same as those described with reference to FIG. 3, and will not be described here.

On the other hand, in this embodiment, the protective layer 20 is located on both sides of the porous current collector.

1 and 3, except that the current collector 10 includes the gap 10a and the protective layer 20 is located on both sides of the current collector 10 in the present embodiment, The detailed description of the other components is omitted.

Next, a method of manufacturing a lithium metal anode according to an embodiment of the present invention will be described.

FIG. 5 schematically shows a method of manufacturing a lithium metal anode according to an embodiment.

Referring to FIG. 5, a method of manufacturing a lithium metal anode according to the present invention includes the steps of preparing a current collector (S10), forming a protective layer (S20) covering at least one surface of the current collector Placing a current collector on which the protective layer is formed, placing a lithium source at a predetermined distance from the protective layer, and applying a current between the current collector and the lithium source to form a lithium metal To form a lithium metal layer (S30).

First, in the step of preparing the current collector (S10), at least one of the current collector including the concave portion and the porous current collector is provided on the current collector, for example, at least one surface.

At this time, the current collector including the concave portion on one surface can be manufactured by a method of forming a concave portion on the surface of the flat current collector by, for example, etching.

The porous current collector including the void may be formed by forming a porous current collector including voids by adjusting the process conditions for sintering the metal powder constituting the current collector such as copper or by forming a gap In the presence of a catalyst.

Next, a step (S20) of forming a protective layer to cover at least one surface of the current collector is performed.

At this time, the step of forming the protective layer may be performed by at least one of physical vapor deposition, scribe printing, vacuum deposition, spray coating, spin coating, dip coating, gravure coating, bar coating and hot pressing .

Here, the hot-pressing may be performed by forming a separate film by a process such as tape casting, extrusion, roll compaction, etc., and then applying heat to at least one surface of the current collector to press- can do. At this time, the hot pressing may be performed by applying heat in the range of 40 to 80 ° C, if necessary.

Thereafter, a step (S30) of forming a lithium metal layer on the collector on which the protective layer is formed is performed.

6A and 6B show more specifically the step of forming the lithium metal layer.

6A, a current collector 10 having a protective layer 20 formed thereon is placed in a plating liquid 300, and a lithium source 210 is placed at a predetermined interval on one side of the protective layer 20 And then a current is applied between the current collector 10 and the lithium source 210 to form a lithium metal layer.

That is, a lithium metal layer in which a lithium metal is located in a concave portion or a cavity of the current collector 10 is formed by using an electroplating (electrodeposition) process, which is one of the electrochemical methods.

6A, the current collector 10 and the lithium source 210 in which the protection layer 20 is formed are positioned and a current is supplied to the current collector 10 and the lithium source 210 using a power supply device . At this time, the current collector 10 is connected to the (-) electrode and the lithium source 210 is connected to the (+) electrode.

At this time, since the protective layer 20 is nonconductive to electrons, it can conduct without reacting with lithium ions (Li ⁺ ) emitted from the lithium source 210.

That is, when the positive electrode is connected to the lithium supply source 210 and the current collector 10 is connected to the negative electrode, Li + ions emitted from the lithium source 210 pass through the protective layer 20, 10) and is placed in a lithium metal (Li ⁰ ) state in the recess or the cavity of the current collector 10. [Li ⁺ + e- = Li ⁰ (metal)]

6B, after the current collector 10 having the protective layer 20 formed on both surfaces thereof is positioned in the plating liquid 300, the lithium secondary battery 10 is placed at a predetermined interval from the protective layer 20, A lithium metal layer may be formed by placing an electric current between the current collector 10 and the lithium source 210 after locating the current collector 210.

Except for placing the lithium source 210 above and below the protective layer 20 to perform the electrodeposition process, details of the same process as that described with reference to FIG. 6A will be omitted.

6B, in the step of forming the lithium metal layer, the porous insulating layer 220 can be positioned between the lithium supply source 210 and the protective layer 20, if necessary. As the porous insulating film 220, for example, a polyolefin-based separation membrane, a polyethylene or polypropylene separation membrane used for a lithium secondary battery, and the like will be described in detail later.

When the porous separator 220 is positioned between the lithium supply source 210 and the protection layer 20 without a predetermined gap therebetween, the lithium supply source 210 and the protection layer 20, the porous separator, When the pressure is applied to the entire surface, the gap between the electrode and the current collector is minimized. Accordingly, the voltage applied to flow the same current decreases, and the generated lithium metal layer can contribute to forming the lithium metal layer densely without growing into a porous or dendritic structure.

At this time, the plating solution includes an auxiliary solvent capable of conducting lithium ion and an additive.

The auxiliary solvent is an organic solvent such as ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2- (DEC), diethyl carbonate (DEC), dipropyl carbonate (DEC), ethylmethyl carbonate (DMC), methyl ethyl ketone The solvent may be selected from the group consisting of carbonate (EMC), methylpropyl carbonate, ethylpropyl carbonate, dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methylpropyl ether, ethylpropyl ether, methyl acetate, ethyl acetate, Ethyl propionate, propyl propionate,? -Butyrolactone,? -Valerolactone,? -Caprolactone,? -Valerolac , Ε- caprolactone may include a lactone, and at least one of the mixtures thereof.

The additive is selected from the group consisting of F ^- , Cl ^- , Br ^- , I ^- , NO ₃ ^- , N (CN) ₂ ^- , BF ₄ ^- , ClO ₄ ^- , PF ₆ ^- , (CF ₃ ) ₂ PF ₄ ^{- _{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 ^- .

The lithium metal anode manufactured by the method according to the above embodiments can be usefully used as a cathode of a lithium secondary battery. That is, the lithium secondary battery according to one embodiment includes the anode, the electrolyte, and the separator together with the lithium metal cathode described above.

7 schematically shows a structure of a lithium secondary battery according to an embodiment of the present invention.

7, the lithium secondary battery 100 includes an electrode assembly including a cathode 112, a cathode 111, and a separation membrane 113 disposed between the anode 112 and the cathode 111 can do.

Such an electrode assembly is wound or folded and housed in a battery container.

Thereafter, an electrolyte is injected into the battery container and sealed to complete the lithium secondary battery 100. At this time, the battery container may have a cylindrical shape, a square shape, a pouch shape, a coin shape, or the like.

The cathode 10 uses the lithium metal cathode 10 according to the above-described embodiments.

The anode 70 may include a cathode active material layer and a cathode current collector.

The cathode active material layer may include at least one of, for example, LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiCoPO ₄ , LiFePO ₄ , LiNiMnCoO ₂ and a compound represented by the following general formula (1) or a mixture thereof.

[Chemical Formula 1]

LiNi _1-xyz Co _x M1 _y M2 _z O ₂

In Formula 1, M 1 and M 2 are independently at least one of Al, Ni, Co, Fe, Mn, V, Cr, Ti, W, Ta, Mg and Mo, 0.5, 0? Z < 0.5, and x + y + z?

Optionally, a conductive material may be added to the cathode active material layer.

The conductive material may be, for example, carbon black and ultrafine graphite particles, fine carbon such as acetylene black, nano metal particle paste, and the like, but is not limited thereto.

The positive electrode collector serves to support the positive electrode active material layer. As the positive electrode collector, for example, an aluminum foil, a nickel foil or a combination thereof may be used, but the present invention is not limited thereto.

As the electrolyte 80 to be filled in the lithium secondary battery 100, a non-aqueous electrolyte or a solid electrolyte may be used.

The non-aqueous liquid electrolyte may include an organic solvent and an electrolyte salt.

The organic solvent is, for example, ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate , 2,3-pentylene carbonate, vinylene carbonate, vinylethylene carbonate, fluoroethylene carbonate (FEC), dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate Methyl ethyl ketone, ethyl propyl carbonate, dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, Propionate, γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, ε-capro Of the tone, and mixtures thereof can include at least one.

The electrolyte salt may, for ^{example, 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 - at least one ^- and _{(CF 3 CF 2 SO 2)} 2 N .

As the solid electrolyte, for example, a gel polymer electrolyte obtained by impregnating a polymer electrolyte such as polyethylene oxide or polyacrylonitrile with an electrolytic solution, or an inorganic solid electrolyte such as LiI or Li ₃ N can be used.

The separator 113 separates the positive electrode and the negative electrode and provides a passage for lithium ion, and any separator may be used as long as it is commonly used in a lithium secondary battery. That is, it is possible to use an electrolyte having a low resistance to ion movement and an excellent ability to impregnate an electrolyte. The separation membrane may be formed of a material selected from the group consisting of, for example, polyethylene, polypropylene, polybutylene, polypentene, polyethylene terephthalate, polybutylene terephthalate, But are not limited to, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenylene oxide, oxide, polyphenylene sulfide and polyethylene naphthalate, or a mixture thereof, and may be in the form of a nonwoven fabric or a woven fabric.

When the solid electrolyte is used as the electrolyte, the solid electrolyte may also serve as the separation membrane 113.

Hereinafter, the present invention will be described in more detail with reference to experimental examples. These experimental examples are only for illustrating the present invention, and the present invention is not limited thereto.

Example  One

(1) Preparation of positive electrode

95% by weight of LiCoO ₂ as a cathode active material, 2.5% by weight of carbon black (Super-P) as a conductive material, and 2.5% by weight of polyvinylidene fluoride as a binder were mixed to prepare a cathode active material slurry.

Next, the above-mentioned cathode active material slurry was applied to an aluminum foil current collector and dried to prepare a cathode.

(2) Manufacture of cathodes

A copper collector current collector having an average pore size of 5 탆 and a porosity of 60% was prepared.

A polyvinylidene fluoride-hexafluoropropylene (PVDF-co-HFP) film having a thickness of 5 μm was hot-pressed on both sides of the copper foams to produce a negative electrode current collector having a protective layer formed thereon.

Next, a lithium metal anode was produced by the same process as shown in FIG.

First, a plating solution 300 composed of DME (dimethyl ether) solution in which 3M LiFSI (lithium bis (fluorosulfonyl) imide) was dissolved was prepared.

A lithium supply source 210 and an anode current collector 10 having the protection layer 20 formed thereon are stacked in the plating liquid 300 at predetermined intervals and then a lithium source 20 and a protective layer A lithium metal layer is formed so that the lithium metal is located inside the voids of the current collector 10 by applying a current to the current collector 10 formed with the positive electrode 20 as a positive electrode and a negative electrode respectively, . At this time, the average current density of the process was 0.2 mA / cm ² and the process time was about 20 hours. The amount of lithium metal electrodeposited to the void portion of the current collector 10 was set to 25 wt% based on the total weight of the negative electrode collector and the protective layer.

(3) Production of lithium secondary battery

An electrode assembly was prepared by interposing a polypropylene porous film between the prepared anode and cathode.

The electrode assembly was inserted into the case of the coin cell 2032, the electrolyte was injected, and the battery was sealed to fabricate a lithium secondary battery. At this time, a mixed solvent (EC: EMC = 3: 7, volume ratio) of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) was used as the electrolyte.

Comparative Example  One

(1) Preparation of positive electrode

A positive electrode was prepared in the same manner as in (1) of Example 1 above.

(2) Manufacture of cathodes

A 20 탆 thick lithium metal layer was formed on both sides of a copper foil by physical vapor deposition (PVD). A polyvinylidene fluoride-hexafluoropropylene (PVDF-co-HFP) film having a thickness of 5 탆 was hot-pressed on the lithium metal layer to form a negative electrode having a lithium metal layer and a protective layer successively laminated on both sides of the current collector .

(3) Production of lithium secondary battery

A lithium secondary battery was produced in the same manner as in (3) of Example 1 above.

Experimental Example  1 - measure the short-circuit point of the battery and Charging and discharging  Life evaluation

The lithium secondary battery produced in Example 1 and Comparative Example 1 was repeatedly charged and discharged, and the short circuit point of the battery was measured. The results are shown in Table 1 below.

Table 2 shows the results of evaluating the charge-discharge lifetime based on 80% of the initial discharge capacity.

The charging step was charged with a constant current up to 4.25V at 0.2C and then charged up to 4.25V to 0.05C. The discharging step was discharged at a constant current of 0.5C to 3.0V.

division When the battery is short-circuited Example 1 After 150 cycles Comparative Example 1 After 40 cycles

division Charge / discharge life (times) Example 1 57 Comparative Example 1 7

Referring to Table 1, in the case of the lithium secondary battery produced according to Example 1, the battery short-circuit occurred after 150 cycles of charging and discharging. On the other hand, in the case of the lithium secondary battery produced according to Comparative Example 1, a short circuit of the battery occurred after 40 cycles, which is about a quarter of the level of Example 1, which is about 26%.

Therefore, a lithium metal cathode having a structure including a lithium metal layer formed by electrodeposition of lithium metal in a concave portion or pore of a current collector including a concave portion or a pore and a protective layer covering the current collector and the lithium metal layer, It can be confirmed that the stability and lifetime characteristics of the battery are remarkably improved when applied to a lithium secondary battery.

The charge / discharge characteristics of the lithium secondary battery including the lithium metal negative electrode according to Example 1 were 8 times or more superior to those of Comparative Example 1, as shown in Table 2. Therefore, when a lithium metal anode according to the embodiments is applied, a lithium secondary battery having excellent charge / discharge characteristics can be realized.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. As will be understood by those skilled in the art. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

100: Lithium secondary battery
111: Lithium metal cathode
112: anode
113: Membrane
10: The whole house
20: Protective layer
30: Lithium metal layer
10a: concave portion, air gap
300: plating solution
210: source of lithium
220: porous insulating film

Claims (18)

A current collector which is at least one of a current collector including a concave portion on at least one side and a porous current collector including a gap;
A protective layer disposed on at least one surface of the current collector; And
A lithium metal layer including metal lithium located in a concave portion or a gap of the current collector;
&Lt; / RTI &gt; The method according to claim 1,
And the concave portion is located on both surfaces of the current collector. The method according to claim 1,
And the horizontal cross-sectional area of the concave portion is 30% to 50% of the horizontal cross-sectional area of the current collector. The method according to claim 1,
Wherein the porosity of the porous collector is 20% to 80%.
Wherein the average diameter of the pores contained in the porous current collector is 5 to 500 占 퐉. The method according to claim 1,
Wherein an average thickness of the current collector including the concave portion on at least one surface thereof is 30 占 퐉 to 100 占 퐉. The method according to claim 1,
Wherein the average thickness of the porous current collector including the void is 20 占 퐉 to 200 占 퐉. The method according to claim 1,
The protective layer may be formed,
(PEO), polyacrylonitrile (PAN), polymethylmethacrylate (PMMA), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF- HFP), LiPON, Li ₃ N, Li _x La _{1 - x} TiO ₃ (0 <x <1), Li ₂ S-GeS-Ga ₂ S ₃ and mixtures thereof. The method according to claim 1,
Wherein the average thickness of the protective layer is 0.01 탆 to 50 탆. The method according to claim 1,
Wherein the lithium metal layer comprises
Wherein the lithium metal is formed so as to fill 40% by volume to 60% by volume of the total volume of the concave portion or the pore of the current collector. Preparing a current collector that is at least one of a current collector including a concave portion on at least one side thereof and a porous current collector including a gap;
Forming a protective layer to cover at least one surface of the current collector;
Placing a current collector on which the protective layer is formed in a plating solution and locating a lithium source at a predetermined distance from the protective layer; And
A current is applied between the current collector and the lithium source to form a lithium metal layer by locating a lithium metal in a recess or a cavity of the current collector
And a cathode. 11. The method of claim 10,
Wherein the forming the lithium metal layer comprises:
Wherein lithium ions supplied from the lithium source are passed through the protective layer so that lithium metal is located in the concave portion or the pore of the current collector. 11. The method of claim 10,
The step of forming the protective layer may include:
A method for producing a lithium metal anode, which is carried out by at least one of physical vapor deposition, scribe printing, vacuum deposition, spray coating, spin coating, dip coating, gravure coating, bar coating and hot pressing. 13. The method of claim 12,
Wherein the step of forming the protective layer comprises a step of heat treating at a temperature in the range of 40 to 80 占 폚. 11. The method of claim 10,
The step of locating the current collector on which the protective layer is formed in the plating solution and locating the lithium source at a predetermined distance from the protective layer,
And placing a porous insulating film between the protective layer and the lithium source. 11. The method of claim 10,
Wherein the plating liquid comprises an auxiliary solvent and an additive. 16. The method of claim 15,
The co-
Ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methyl propyl carbonate, ethyl propyl carbonate (DMSO), and the like. Dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, Butyrolactone,? -Valerolactone,? -Caprolactone,? -Valerolactone,? -Caprolactone, and mixtures thereof Method for producing a lithium metal cathode comprising one. 16. The method of claim 15,
Preferably,
^{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 -, At least one of 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 ^- . cathode;
anode; And
Comprising an electrolyte,
The negative electrode is the lithium metal negative electrode according to any one of claims 1 to 9.

Images