KR20170126404A - Negative electrode for lithium metal battery and lithium metal battery comprising the same - Google Patents

Abstract

Disclosed are a negative electrode for a lithium metal battery and the lithium metal battery including the same. The negative electrode for a lithium metal battery includes: a lithium metal electrode including lithium metal or lithium metal alloy materials; and a protective film arranged on at least one part of the lithium metal electrode. Youngs modulus of the protective film is 10^6 Pa or greater. The protective film can include one or more particles selected from a group including organic particles, inorganic particles, and organic-inorganic particles in the size of 1-100 m while having a crosslinked product of polymerizable oligomers present between the particles therein.

Description

[0001] The present invention relates to a negative electrode for a lithium metal battery and a lithium metal battery including the negative electrode,

A negative electrode for a lithium metal battery and a lithium metal battery including the same are presented.

Lithium secondary batteries are high performance secondary batteries having the highest energy density among currently commercialized secondary batteries and can be used in various fields such as electric vehicles.

As the cathode of the lithium secondary battery, a lithium metal thin film may be used. When such a lithium metal thin film is used as a negative electrode, reactivity with a liquid electrolyte during charging and discharging is high due to high reactivity of lithium. Or a dendrite is formed on the lithium negative electrode thin film, so that the lifetime and stability of the lithium secondary battery employing the lithium metal thin film may be deteriorated, and improvement is required.

One aspect is to provide a negative electrode for a lithium metal battery having a protective film excellent in mechanical properties.

Another aspect is to provide a lithium metal battery including the above-described cathode and having improved cell performance.

On one side

A lithium metal electrode comprising a lithium metal or a lithium metal alloy; And

And a protective film disposed on at least a portion of the lithium metal electrode,

Young's modulus of the protective film is 10 ⁶ Pa or more,

Wherein the protective film comprises at least one particle selected from organic particles, inorganic particles and organic particles having a size of more than 1 탆 and not more than 100 탆,

There is provided a negative electrode for a lithium metal battery containing a crosslinked material of a polymerizable oligomer existing between particles in the protective film.

The polymerizable oligomer may have ionic conductivity.

According to another aspect, an anode; The cathode described above; And an electrolyte interposed therebetween are provided.

The negative electrode for a lithium metal battery according to an embodiment has a protective film in which a crosslinked body of a polymerizable oligomer is present between particles, thereby improving mechanical properties such as strength. When a negative electrode having such a protective film is used, it is possible to manufacture a lithium metal battery in which the volume change during charging and discharging of the battery is effectively suppressed and the cycle life and discharge capacity are improved.

FIGS. 1A to 1D schematically illustrate structures of cathodes for a lithium metal battery according to one embodiment.
FIGS. 1E and 1F are diagrams for explaining the principle of the lithium dendrite growth inhibition and guide in the cathode for a lithium metal battery according to one embodiment. FIG.
FIGS. 1G to 1K are views schematically showing a structure of a lithium metal battery according to an embodiment.
FIGS. 11 and 12 show the structure of a cathode for a lithium metal battery according to an embodiment.
FIG. 1n shows a structure of a protective film according to an embodiment.
2A to 2D are electron micrograph (SEM) photographs showing cross sections of the lithium negative electrode prepared according to Example 1. Fig.
3A to 3C are SEM photographs showing the surface of a lithium negative electrode manufactured according to Example 5. FIG.
FIGS. 3D and 3E show scanning electron microscopy (SEM) / energy dispersive spectroscopy (SEM / EDS) analysis results of the negative electrode prepared in Example 1. FIG.
FIGS. 3F and 3G show the results of the thickness variation distribution of the lithium metal battery produced according to Example 10 and Comparative Example 1, respectively.
3H is a SEM photograph of a lithium negative electrode manufactured according to Example 23. Fig.
4A is a schematic cross-sectional view of a cathode in which a lithium electrodeposited layer is formed in the lithium metal battery according to the thirteenth embodiment.
4B and 4C are SEM photographs showing the surface of the negative electrode in the lithium metal battery manufactured according to Example 1. FIG.
FIG. 4D is a SEM photograph showing a cross-sectional state of a lithium negative electrode having a lithium electrodeposited layer formed on a negative electrode in a lithium metal battery manufactured according to Example 1. FIG.
5A schematically shows a cross-sectional structure of a negative electrode in a lithium metal battery according to Comparative Example 1. FIG.
5B and 5C are SEM photographs showing the surface of a negative electrode in a lithium metal battery manufactured according to Comparative Example 1. FIG.
FIG. 5D is an SEM photograph showing a cross-sectional state of a lithium negative electrode having a lithium electrodeposited layer formed on a negative electrode in a lithium metal battery manufactured according to Comparative Example 1. FIG.
6 shows the impedance measurement results of the lithium metal battery produced according to Examples 18 and 20 and Comparative Example 1. Fig.
7 shows the capacity retention rate change of the lithium metal battery produced according to Example 22 and Comparative Example 5. Fig.
Fig. 8 is a graph showing changes in discharge capacity with respect to the lithium metal battery produced in Example 13 and Comparative Example 1. Fig.
9A to 9C show a state in which particles are arranged on the surface of a lithium metal electrode in a protective film according to an embodiment.
10 is a graph showing changes in cell thickness according to a cycle in a lithium metal battery manufactured according to Example 22 and Comparative Example 1. Fig.
Fig. 11 shows the discharge capacity change in the lithium metal battery produced according to Example 9 and Comparative Example 1. Fig.
12 is a graph showing cell resistance characteristics after repeating 100 cycles in the lithium metal battery according to Example 9 and Comparative Example 1. Fig.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an exemplary negative electrode for a lithium metal battery and a lithium metal battery including the same will be described in detail with reference to the accompanying drawings.

A lithium metal electrode comprising a lithium metal or a lithium metal alloy; And a protective film disposed on at least a portion of the lithium metal electrode. The protective film has a Young's modulus of 10 ⁶ Pa or more, and the protective film has a size of more than 1 탆 and less than 100 탆. a crosslinked polymeric oligomer having at least one particle selected from organic particles, inorganic particles and orgnic-inorganic particles and having a weight average molecular weight of not more than 5,000 existing between the particles in the protective film A negative electrode for a lithium metal battery is provided.

The lithium metal or the lithium metal alloy has a large electric capacity per unit weight, and it is possible to realize a high capacity battery. However, in the case of the lithium metal or the lithium metal alloy, the dendrite may grow during the process of removing / attaching lithium ions, which may cause a short circuit between the anode and the cathode. The lithium metal or lithium metal alloy electrode has a high reactivity to the electrolyte, which may cause side reactions with the electrolyte, thereby deteriorating the cycle life of the battery. In order to compensate for this, a protective film that can complement the surface of lithium metal or lithium metal alloy is required. Accordingly, the present inventors provide a negative electrode for a lithium metal battery having a novel protective film of a lithium metal electrode that can overcome the above-described problems.

The protective film may be at least one particle selected from among organic particles, inorganic particles and orgnic-inorganic particles having a size of more than 1 탆 and not more than 100 탆, And a crosslinked product of a polymerizable oligomer. The crosslinked product of the polymerizable oligomer fills voids and pores between the particles described above. By having such a structure, the protective film has an integral high strength.

The polymerizable oligomer is an oligomer having a crosslinkable functional group and has a weight average molecular weight of 5,000 or less, for example, 2,000 or less, such as 1,000 or less, such as 200 to 1,000, specifically 200 to 500. With such a weight average molecular weight, the polymerizable oligomer is in a liquid state or dissolved in a solvent to be easily injected. Such polymerizable oligomers will have low viscosity characteristics in the range of 3 to 50 cP. In the case of having such a viscosity range, the composition containing the polymerizable oligomer can easily pass through the space between the particles of the protective film to fill the protective film, thereby making it possible to manufacture a protective film having high strength.

The weight average molecular weight of the crosslinked product of the polymerizable oligomer may be from 10,000 to 30.

The cross-linking degree of the cross-linked product of the polymerizable oligomer is, for example, 90 to 100%.

Polymerizable oligomers include, for example, diethylene glycol diacrylate (DEGDA), triethylene glycol diacrylate (TEGDA), tetraethylene glycol diacrylate (TTEGDA), polyethylene glycol diacrylate (PEGDA), dipropylene glycol di Acrylate (DPGDA), tripropylene glycol diacrylate (TPGDA), ethoxylated trimethylolpropane triacrylate (ETPTA), acrylate-functionalized ethylene oxide Ethoxylated neopentyl glycol diacrylate (NPEOGDA), propoxylated neopentyl glycol diacrylate (NPPOGDA), trimethylolpropane triacrylate (TMPTA), trimethylolpropane triacrylate Tri (meth) acrylate (TMPTMA), pentaerythritol triacryl (PETA), ethoxylated propoxylated trimethylolpropane triacrylate (TMPEOTA) / (TMPPOTA), propoxylated glyceryl triacrylate, tris (2-hydroxyethyl) isocyanurate tri Acrylate (THEICTA), pentaerythritol tetraacrylate (PETTA), and dipentaerythritol pentaacrylate (DPEPA).

The polymerizable oligomer and the crosslinked product of the polymerizable oligomer formed therefrom may have ionic conductivity. When the cross-linked product of the polymerizable oligomer and the polymerizable oligomer has ionic conductivity, the conductivity of the protective film can be further improved.

In the protective film according to an exemplary embodiment, the content of the crosslinking product of the polymerizable oligomer is 10 to 50 parts by weight, for example, 20 to 40 parts by weight, based on 100 parts by weight of the particles. When the content of the cross-linked product of the polymerizable oligomer is in the above range, the mechanical properties of the protective film are excellent.

The protective film according to another exemplary embodiment may be formed of one or more selected from among organic particles, inorganic particles, and orgnic-inorganic particles having a size of more than 1 탆 and not more than 100 탆. In addition to the particles, the particles and the second particles having a small size. In addition to the second particle, a plurality of particles having different sizes may be included.

The size of the second particles is selected to be smaller than the size of the first particles. The size of the second particle ranges from 1 to 100 mu m. The first particles of the protective film may have a size of, for example, 3 mu m and the second particles may have a size of 1 mu m. The mixing ratio of the first particle and the second particle is not particularly limited, and may be, for example, from 1:99 to 99: 1 by weight, specifically from 10: 1 to 2: 1 by weight.

Young's modulus of the protective film is 10 ⁶ Pa or more, for example, 10 ⁸ to 10 ¹⁰ Pa, and thus the Young's modulus of the protective film is very excellent and the mechanical properties are excellent.

The Young's modulus has the same meaning as the tensile modulus. The tensile modulus is measured using a dynamic mechanical analysis system (DMA800, TA Instruments), and the protective film specimen is prepared using ASTM standard D412 (Type V specimens). And the tensile modulus of the protective film is measured at a rate of 5 mm per minute at 25 ^° C and a relative humidity of about 30%. The tensile modulus is evaluated from the slope of the thus obtained stress-strain curve.

At least one of the particles in the protective film may have a crosslinked structure. The particles having a chemically or physically crosslinked structure are defined as including organic particles of a crosslinked polymer obtained from a polymer having a crosslinkable functional group, inorganic particles having a structure crosslinked by a crosslinking functional group present on the surface, and the like . Examples of the crosslinkable functional group include functional groups participating in the crosslinking reaction such as acrylic group, methacrylic group and vinyl group.

Cross-linking may proceed by applying heat or by irradiating light such as UV. Here, heat or light can be applied in a range that does not adversely affect the lithium metal electrode.

The particles having a chemically crosslinked structure are crosslinked using chemical methods (i.e., chemical reagents) so as to enable bonding of crosslinkable functional groups present in the material constituting the particles. And particles having a physically crosslinked structure are crosslinked by a physical method. Physical methods include, for example, heating to reach the glass transition temperature of the polymer constituting the particles, although the crosslinking is not formed by the chemical reagent so as to enable the bonding of the crosslinkable functional groups. Crosslinking may occur within the particle itself and may also proceed between adjacent particles in the protective film.

The lithium metal or lithium metal alloy used as the lithium metal electrode has a thickness of 100 mu m or less, for example, 80 mu m or less, or 50 mu m or less, or 30 mu m or less, or 20 mu m or less. According to another embodiment, the thickness of the lithium metal electrode is 0.1 to 60 占 퐉. Specifically, the thickness of the lithium metal or the lithium metal alloy is 1 to 25 占 퐉, for example, 5 to 20 占 퐉.

The particles may be spherical, microsphere, rod-shaped, ellipsoidal, radial, etc., or combinations thereof. When the particles are spherical, for example, they may be microspheres having an average particle size exceeding 1 탆 and a size of 100 탆 or less. The average particle size of the microspheres may be, for example, 1.5 to 75 占 퐉, for example 1.5 to 50 占 퐉, or 1.5 to 20 占 퐉 or, for example, 1.5 to 10 占 퐉.

FIG. 1L is a view for explaining the protective role of the lithium metal electrode in the case where the particle size of the microspheres contained in the protective film in the anode for a lithium metal battery according to an embodiment is more than about 1 μm and 100 μm, This is to explain the protective role of the lithium metal electrode when the average particle diameter of the microspheres contained in the protective film in the negative electrode for a lithium metal battery is 1 탆 or less.

Referring to this, a protective film 12 including a microsphere 13a is laminated on a lithium metal electrode 11. The surface coating fraction of the microspheres contained in the protective film formed on the lithium metal electrode and the particle spacing of the microspheres are factors that directly affect the protective film function of the lithium metal electrode. As used herein, the term "surface coating fraction" refers to the surface area of a lithium metal electrode comprising a protective film over the entire surface area of the lithium metal electrode. The surface coating fraction is, for example, about 80%, about 85%, about 90%, or about 100% of the total surface area of a lithium metal electrode.

The lithium metal electrode 11 is, for example, a lithium metal, and the lithium metal electrode 11, as shown in FIG. 11, has a thickness of, for example, 5 to 50 占 퐉, For example, 10 to 30 占 퐉, for example, 15 to 25 占 퐉, and has a surface step difference of about 占 1 占 퐉. In protecting the lithium metal electrode having such a surface step difference, when the average particle diameter is more than 1 占 퐉 and less than 100 占 퐉, the use of the microspheres 13a is very excellent in protecting the lithium metal electrode.

On the other hand, when the protective film 12 stacked on the lithium metal electrode 11 as shown in FIG. 1M contains microspheres having an average particle diameter of 1 μm or less, for example, a microsphere having a particle diameter of 5 nm to 300 nm The aggregation and surface coating fraction of the microspheres are reduced. As a result, the degree of porosity in the protective film becomes large, so that it is advantageous for the liquid electrolyte to contact the lithium metal.

When the particles are of the spherical type, the size indicates the average particle diameter, and when the particles are the rod-shaped type, the size indicates the long axis length. If the particles are of the rod-type type, the ratio of the transverse and longitudinal axes can be, for example, from 1: 1 to 1:30, for example from 1: 2 to 1:25, for example from 1: 5 to 1:20 .

As used herein, the term "average particle size" or "average particle diameter" means that 50% or more of the particles in a distribution curve, (D50). ≪ / RTI > The total number of accumulated particles here is 100%. The average particle size is measurable according to methods known to those skilled in the art. For example, the average particle size can be measured using a particle size analyzer, TEM or SEM image. As another method of measuring the average particle size, there is a method using a measuring device using dynamic light scattering. According to this method, the number of particles having a predetermined size range can be counted, from which the average particle size can be calculated.

Porosity is defined herein as the void volume (i.e., voids or pores) measured in a material and is determined by the volume percentage of voids in the material based on the total volume of the material.

The particles of the protective film may be any polymer used for forming a protective film.

According to another embodiment, the particles of the protective film may be made of a polymer having a low wettability to a liquid electrolyte.

The particles of the protective film may include at least one selected from i) a copolymer containing polystyrene, a styrene repeating unit, a copolymer containing a repeating unit having a crosslinkable functional group, and ii) a crosslinking polymer.

The particles of the protective film may be a polymer (homopolymer or copolymer) containing a styrene-based repeating unit. In the case of a polymer having a styrenic repeating unit, the polymer has hydrophobicity so that it does not adversely affect the lithium metal electrode and has little electrolyte wettability, so that the reactivity between the lithium metal electrode and the electrolyte can be minimized.

At least one of the particles is selected from the group consisting of polystyrene, poly (styrene-divinylbenzene) copolymer, poly (methyl methacrylate-divinylbenzene) copolymer, poly (ethyl methacrylate- divinylbenzene) (Methacrylate-divinylbenzene) copolymer, poly (butyl methacrylate-divinylbenzene) copolymer, poly (propyl methacrylate-divinylbenzene) (Styrene-acrylonitrile) copolymer, poly (styrene-vinylidene chloride) copolymer, poly (acrylonitrile-butadiene-styrene) copolymer, poly Acrylonitrile-butadiene-styrene) copolymer, poly (methacrylate-butadiene-styrene) copolymer, poly (styrene- (C1 -C9alkyl Acrylate copolymer) and at least one polymer A selected from the group consisting of poly (acrylonitrile-styrene- (C1-C9 alkyl) acrylate) copolymers and crosslinked polymers.

The cross-linking polymer may be, for example, a poly (styrene-divinylbenzene) copolymer, a poly (methyl methacrylate-divinylbenzene), or a cross-linked product formed by cross- .

When the above-mentioned copolymer contains a styrene-based repeating unit, the content of the styrene-based repeating unit is from 65 to 99 parts by weight, from 80 to 99 parts by weight, from 90 to 99 parts by weight, based on 100 parts by weight of the total amount of the copolymer, 96 to 99 parts by weight.

In the case where the copolymer contains divinylbenzene, the content of divinylbenzene is 1 to 35 parts by weight, 1 to 20 parts by weight, 1 to 10 parts by weight, 1 to 4 parts by weight, In the range of 3 to 7 parts by weight, specifically 5 parts by weight.

The above-mentioned copolymers include all of block copolymers, random copolymers, alternating copolymers, graft copolymers and the like. The weight average molecular weight of such copolymers is from 10,000 to 200,000 daltons. The copolymer may be, for example, a block copolymer.

The block constituting the copolymer in the copolymer is successively divided into a block (first block) containing a first repeating unit, a block including a second repeating unit (second block) and a block including a third repeating unit Third block).

The block containing the first repeating unit has a weight average molecular weight of 10,000 Daltons or more, for example, 10,000 to 500,000 Daltons, specifically 15,000 to 400,000 Daltons. According to another embodiment, the weight average molecular weight of the block containing the first repeating unit is 20,000 to 200,000 Daltons. The content of the block containing the first repeating unit is 20 to 50 parts by weight, for example, 20 to 40 parts by weight, for example, 22 to 30 parts by weight, based on 100 parts by weight of the total weight of the block copolymer. When such a polymer block is used, a protective film excellent in mechanical properties such as strength can be obtained.

The weight average molecular weight of the block containing the second repeating unit is at least 10,000 Daltons, for example 10,000 to 510,000 Daltons, specifically 15,000 to 400,000 Daltons. According to another embodiment, the weight average molecular weight of the block containing the second repeating unit is 20,000 to 200,000 Daltons. When such a hard block having a weight average molecular weight is used, a protective film excellent in ductility, elasticity and strength can be obtained.

The weight average molecular weight herein is measurable using methods well known to those skilled in the art. For the weight average molecular weight, for example, gel permeation chromatography (GPC) is used.

The block copolymer is at least one selected from a diblock copolymer (A-B) and a triblock copolymer (A-B-A 'or B-A-B').

The total content of the first block and the third block in the above-mentioned triblock copolymer including the first block, the second block and the third block is 20 to 35 parts by weight, preferably 20 to 40 parts by weight based on 100 parts by weight of the total weight of the block copolymer, For example, 22 to 30 parts by weight, and the content of the second block is 65 to 80 parts by weight, for example, 70 to 78 parts by weight, based on 100 parts by weight of the block copolymer.

The particles of the protective film may be selected from the group consisting of polyvinylpyridine, polyvinylcyclohexane, polyglycidyl acrylate, poly (2,6-dimethyl-1,4-phenylene oxide), polyolefin, poly (tertbutyl vinyl ether), polycyclohexyl At least one selected from the group consisting of vinyl ether, polyvinyl fluoride, poly (styrene-maleic anhydride) copolymer, polyglycidyl methacrylate, polyacrylonitrile and polymeric ionic liquids (PIL) . ≪ / RTI >

The particles of the protective film may be selected from the group consisting of a poly (styrene-divinylbenzene) copolymer, a poly (methyl methacrylate-divinylbenzene) copolymer, a poly (ethyl methacrylate-divinylbenzene) Poly (methyl methacrylate-divinylbenzene) copolymers, poly (butyl methacrylate-divinylbenzene) copolymers, poly (propyl methacrylate-divinylbenzene) (Ethyl acrylate-divinylbenzene) copolymer, poly (pentyl acrylate-divinylbenzene) copolymer, poly (butyl acrylate-divinylbenzene) copolymer, poly (propyl acrylate-divinylbenzene) And poly (acrylonitrile-butadiene-styrene) copolymers.

When the particles of the protective film include the above-mentioned crosslinked polymer, the particles are connected to each other through crosslinking, so that the mechanical strength of the protective film is excellent. The crosslinked polymer of the protective film has a degree of crosslinking of 10 to 30%, for example, 12 to 28%, for example, 15 to 25%, based on the total volume of the crosslinked polymer.

The protective film according to one embodiment may include a lithium salt or a liquid electrolyte. When the protective film includes a liquid electrolyte, an ion conductive path can be formed through the liquid electrolyte, thereby improving the conductivity of the cathode. And a lithium metal battery having stable cycle characteristics can be produced.

The liquid electrolyte includes at least one selected from an organic solvent, an ionic liquid, and a lithium salt. The liquid electrolyte may comprise from 30 to 60 vol%, for example from 35 to 55 vol%, for example from 40 to 50 vol%, based on the total volume of the protective film in the protective film. The liquid electrolyte accounts for, for example, 40 to 50% by volume in the protective film

The size of at least one particle selected from among organic particles, inorganic particles and organic particles in the protective film according to one embodiment is, for example, 1.1 to 50 μm, for example, 1.1 to 25 μm, for example, 1.5 to 20 μm , Specifically 1.5 to 10 mu m.

The particles may be, for example, poly (styrene-co-divinylbenzene) copolymer microspheres having an average particle size of about 3 탆 in a weight ratio of 1: 1 and poly (styrene-co-divinylbenzene) Poly (styrene-co-divinylbenzene) copolymer microspheres containing copolymer microspheres or having an average particle size of about 3 占 퐉 in a 1: 1 weight ratio and poly (styrene-co-divinylbenzene ) Copolymer microspheres or poly (styrene-co-divinylbenzene) copolymer microspheres having an average particle size of about 3 mu m in a 1: 1 weight ratio and poly (styrene-co-di Vinylbenzene) copolymer microspheres. Here, the mixing weight ratio of microspheres having different average particle diameters can be selected in a weight ratio range of 1: 9 to 9: 1 other than the above-mentioned 1: 1 mixture weight ratio.

According to one embodiment, the particles are microspheres having a monomodal particle size distribution. The monomodal particle size distribution can be measured using a particle diameter analyzer (Dynamic Light Scattering: DLS, Nicomp 380) with a standard deviation of less than 40%, for example up to 20%, for example up to 10% , For example, 1% or more to less than 40% or 2% to 25%, for example, 3% to 10%

When the particles include particles having different sizes from each other, for example, particles having a size of about 8 占 퐉 and particles having a size of about 3 占 퐉 may be contained as large diameter particles. Or particles having a size of about 3 占 퐉 as large diameter particles and particles having a size of about 1.1 占 퐉 or 1.3 占 퐉 as small particle diameter particles. Here, the mixing weight ratio of the large diameter particles to the small particle diameter particles is, for example, 8: 2 to 9: 1.

For example, greater than or equal to 85%, such as greater than or equal to 90%, such as greater than or equal to 95%, such as greater than or equal to 98%, such as greater than or equal to 98 to 100% of the pores of the protective film according to one embodiment. Lt; RTI ID = 0.0 > oligomer. ≪ / RTI >

1A to 1D, a structure of a cathode for a lithium metal battery according to an embodiment will be described. In Figures 1A to 1D, the particles of the protective film have a microsphere shape as a non-limiting example.

1A, a lithium metal electrode 11 made of lithium metal or a lithium metal alloy is laminated on the collector 10, and a protective film 12 is disposed on the lithium metal electrode 11 . The protective film (12) includes particles (13). The protective film 12 can realize a mono disperse layer without aggregation of the particles 13.

Between the particles 13 contained in the protective film, a crosslinked product 15 of a polymerizable oligomer is present. The crosslinked product 15 of the polymerizable oligomer is present in the void space between the particles 13, and the protective film 12 has an integral structure, so that it can have excellent mechanical properties. Therefore, employing such a protective film not only greatly improves the effect of suppressing the growth of lithium dendrite, but also improves the electrodeposition density of lithium at the charge and discharge and is excellent in the conductivity characteristic.

When the crosslinked product 15 of the polymerizable oligomer has ionic conductivity, ions can be transferred through it. Therefore, when such a protective film is employed, the ion conductivity of the cathode can be improved.

The lithium metal alloy includes a metal / metalloid or an oxide thereof capable of being alloyed with a lithium metal and a lithium metal. Sn, Al, Ge, Pb, Bi, Sb, and Si-Y alloys (wherein Y is an alkali metal, an alkaline earth metal, a Group 13 to Group 16 element, (Wherein Y is an alkali metal, an alkaline earth metal, a Group 13 to Group 16 element, a transition metal, a rare earth element, or a combination element thereof, and Sn is a metal element, a rare earth element or a combination element thereof and not Si) , MnOx (0 < x? 2), and the like.

The element Y may be at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ge, P, As, Sb, Bi, Te, Po, or a combination thereof. For example, the metal / metalloid oxide that can be alloyed with the lithium metal may be lithium titanium oxide, vanadium oxide, lithium vanadium oxide, SnO ₂ , SiO _x (0 <x <2), and the like.

As shown in FIG. 1B, the ion conductive polymer 14 may be present around the particle 13. Although not shown in the figure, a crosslinked body 15 of a polymerizable oligomer is present in a space between the particles 13, and a liquid electrolyte may be present.

The ion conductive polymer 14 may further be contained in the protective film 12. And may have a structure surrounding the particles 13 as shown in Fig. 1 (b). The ion-conducting polymer acts as a binder to help immobilize the particles on the lithium metal electrode in the protective film while improving the mechanical strength. The content of the ion conductive polymer is 10 parts by weight or less, for example, 5 parts by weight or less, for example, 2 parts by weight or less, based on 100 parts by weight of the particles. According to another embodiment, the content of the ion conductive polymer is 1 to 10 parts by weight, for example, 1 to 5 parts by weight, specifically 1 to 2 parts by weight, based on 100 parts by weight of the particles. When the content of the ion conductive polymer is within the above range, the mechanical strength of the protective film is excellent, and the lithium dendrite growth can be effectively suppressed.

The ion conductive polymer may be applied to any polymer having ion conductivity selected from, for example, homopolymers and copolymers commonly used in lithium metal batteries.

As the homopolymer, polystyrene, polyvinylidene fluoride, polymethyl methacrylate, polyvinyl alcohol and the like can be used.

The copolymers may be block copolymers, random copolymers, graft copolymers, alternating copolymers, or combinations thereof.

The ion conductive polymer may be, for example, at least one selected from block copolymers including polystyrene and styrene-based repeating units. The ion conductive polymer includes, for example, polystyrene, poly (styrene-divinylbenzene) block copolymer, poly (styrene-isoprene) block copolymer, poly (styrene-isoprene- (Styrene-butadiene-styrene) block copolymer, poly (styrene-butadiene-styrene) block copolymer, poly Poly (styrene-vinylpyridine) block copolymers, poly (acrylonitrile-butadiene-styrene) copolymers, poly (acrylonitrile-ethylene-propylene-styrene) (Methacrylate-butadiene-styrene) copolymers, poly (styrene- (C1-C9 alkyl) acrylate) copolymers and poly (acrylonitrile- Reel-it may be at least one selected from the group consisting of (C1-C9 alkyl) acrylate), copolymers of styrene.

Examples of the poly (C1-C9 alkyl) methacrylate-butadiene-styrene copolymer include poly (methacrylate-butadiene-styrene) ) Copolymer is a poly (styrene-acrylate) copolymer.

The poly (styrene-divinylbenzene) copolymer may be a polymer represented by the following formula (1).

[Chemical Formula 1]

In the general formula (1), a and b are mole fractions, 0.01 to 0.99, respectively, and the sum of a and b is 1. In formula (1), a is, for example, from 0.95 to 0.99, for example from 0.96 to 0.99, specifically from 0.98 to 0.99, and b is from 0.01 to 0.05, for example from 0.01 to 0.04, .

According to another embodiment, a in the general formula (1) is, for example, 0.6 to 0.99 and b is 0.01 to 0.4.

The poly (styrene-divinylbenzene) copolymer may be a polymer represented by the following formula (1a).

[Formula 1a]

The poly (styrene-divinylbenzene) copolymer may be a polymer represented by the following formula (1b).

[Chemical Formula 1b]

4: 1, 5: 1, 6: 1, 7: 1, 8: 1 or 9: 1 by weight, for example, 3: 1 to 9: 1 by weight of the poly (styrene-divinylbenzene) 1.

The poly (acrylonitrile-butadiene-styrene) copolymer is a polymer represented by the following formula (2).

(2)

In Formula 2, x, y and z are mole fractions, 0.01 to 0.99 regardless of each other, and the sum of x, y, and z is 1.

In Formula 2, x is 0.1 to 0.35, y is 0.05 to 0.55, and z is 0.2 to 0.7. For example, x is 0.15-0.35, y is 0.05-0.3, and z is 0.4-0.6.

The poly (acrylonitrile-butadiene-styrene) copolymer has a blend weight ratio of, for example, a polyacrylonitrile block, a polybutadiene block and a polystyrene block of 0.25: 0.25: 0.5. 0.3: 0.3: 0.4, 0.2: 0.2: 0.6, 0.35: 0.35: 0.3, or 0.1: 0.1: 0.8.

The degree of polymerization of the copolymer including the poly (styrene-divinylbenzene) copolymer represented by Chemical Formula 1 and the poly (acrylonitrile-butadiene-styrene) copolymer represented by Chemical Formula 2 is 2 to 5,000, It is a number of 1,000.

The poly (styrene-divinylbenzene) copolymer represented by Formula 1 and the poly (acrylonitrile-butadiene-styrene) copolymer represented by Formula 2 may be, for example, block copolymers.

The protective film according to one embodiment can form the single film structure of the particles 13 as shown in Figs. 1A and 1B.

As shown in FIG. 1C, the protective film according to another embodiment has a two-layer film structure in which the particles 13 are laminated in two layers on the lithium metal electrode 11. The ion conductive polymer 14 may be present around the particle 13 as in the case of Figure 1b and the crosslinked product 15 of the polymerizable oligomer may be present between the spaces between the particles 13. [ The protective layer 12 may have a multi-layered structure by mixing particles 13a, 13b, and 13c having different sizes as shown in FIG. 1d. Between the particles 13a, 13b, and 13c of different sizes in the multilayer film, there is a crosslinked product 15 of a polymerizable oligomer. In the case where the protective film 12 has a multi-layer structure in which the particles 13a, 13b and 13c having different sizes are mixed, the porosity is lowered or the packing density is improved, , Thereby minimizing the lithium metal contact of the electrolyte. It is also possible to suppress the growth of dendrite by increasing the thickness of the protective film.

The particles of the protective film may contain, for example, a poly (styrene-divinylbenzene) copolymer or a crosslinked polymer thereof. When the particles are made of a crosslinked polymer, the particles may be chemically connected to each other. Such a chemically connected structure can form a high-strength microsphere network structure.

The porosity of the protective film is 5% or less, for example, 0.01 to 5%. The pore size and porosity of the protective film are determined according to the particle size.

It is possible to form a uniform thickness because there is substantially no aggregation of particles in the protective film according to one embodiment. The thickness of the protective film is 1 to 10 탆, for example, 2 to 9 탆, for example, 3 to 8 탆. The thickness variation of the protective film is 0.1 to 4 탆, for example, 0.1 to 3, for example, 0.1 to 2 탆.

The protective film includes a lithium salt or a liquid electrolyte. The liquid electrolyte includes a lithium salt and an organic solvent. The lithium salt contained in the protective layer is, for example, _{LiSCN, LiN (CN) 2,} LiClO 4, LiBF 4, LiAsF 6, LiPF 6, LiCF 3 SO 3, LiC (CF 3 SO 2) 3, LiN (SO 2 C 2 _{F 5) 2, LiN (SO} 2 CF 3) 2, LiN (SO 2 F) 2, LiSbF 6, LiPF 3 (CF 2 CF 3) 3, LiPF 3 (CF 3) 3, and LiB (C ₂ O ₄ ) _{2. &} Lt; / RTI &gt;

The content of the lithium salt in the protective film is 10 to 70 parts by weight, for example, 15 to 60 parts by weight, for example, 20 to 50 parts by weight, based on 100 parts by weight of the particles. The ionic conductivity of the protective film is excellent when the content of the lithium salt is in the above range.

Examples of the organic solvent include a carbonate compound, a glycol compound, and a dioxolane compound. The carbonate-based compound includes ethylene carbonate, propylene carbonate, dimethyl carbonate, fluoroethylene carbonate, diethyl carbonate, or ethyl methyl carbonate.

The glycine compound may be selected from the group consisting of poly (ethylene glycol) dimethyl ether (PEGDME, polyglyme), tetra (ethylene glycol) dimethyl ether (TEGDME, tetraglyme) Poly (ethylene glycol) monoacrylate (PEGDL), poly (ethylene glycol) monoacrylate, poly (ethylene glycol) (PEGMA) and poly (ethylene glycol) diacrylate (PEGDA). Examples of the dioxolane-based compound include 3-dioxolane, 4,5-diethyl-1,3-dioxolane, 4,5-dimethyl- 3-dioxolane and 4-ethyl-1,3-dioxolane. The organic solvent may be selected from the group consisting of 2,2-dimethoxy-2-phenylacetophenone, dimethyl ether (DME), 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, gamma butyrolactone, 1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (1,1,2,2-Tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether).

Examples of the organic solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, fluoroethylene carbonate, gamma butyrolactone, dimethoxyethane, diethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether , Tetraethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, succinonitrile, sulfolane, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, adiponitrile and 1,1,2,2-tetrafluoroethyl 2,2 , 3,3-tetrafluoropropyl ether, and the like.

1E and 1F are diagrams for explaining the action and effect of the lithium anode according to one embodiment.

1E, a lithium anode according to an embodiment includes a solid-electrolyte interphase (SEI) formed on a lithium metal electrode 11 and a protective layer 12 containing particles 13 disposed thereon Structure. The lithium metal electrode 11 and the SEI have soft characteristics due to their thickness and the like, and are pressed by the particles 13. As a result, a groove is formed on the lithium metal electrode 11 and the SEI 17. [

The step of the groove is, for example, a maximum of ± 1 um. A crosslinked body 14 of a polymerizable oligomer is disposed in a space between the particles 13. The mechanical strength of the protective film 12 can be further increased due to the cross-linked body 15 of the polymerizable oligomer.

In Fig. 1E, the particles 13 use crosslinked polystyrene (PS) microspheres, for example. The lithium dendrite growth can be suppressed by the force applied by the particles 13 and guided to form lithium dendrites in the space between the particles 13. [ When the negative electrode using such a protective film is filled, the lithium electrodeposition proceeds. As shown in FIG. 1F, the lithium electrodeposited layer 16 is formed on the lithium metal electrode 11, the SEI 17 is stacked thereon, A protective film 12 containing a particle 13 and a crosslinked product 15 of a polymerizable oligomer are stacked. When the protective film described above is employed, the lithium electrodeposition density is greatly improved. And dendrite growth is controlled by providing a dendrite growth space using a network structure and a pore structure, thereby having a function of adsorbing by-products obtained from the anode by controlling dendrite growth. Thus, the lithium metal battery employing such a lithium anode has improved lifetime and high temperature stability .

The electrodeposition density of lithium electrodeposited on the surface of the lithium metal electrode charged in the lithium metal battery employing the negative electrode for a lithium metal battery according to an embodiment is 0.3 to 0.4 g / cm &lt; ³ &gt; (g / cc), for example, 0.325 to 0.4 g / cm &lt; ^{3 &} gt ;. Here, the term &quot; non-pressurized condition "refers to a condition in which the outer surface of the pouch cell is not subjected to pressurization using a glass plate or an additional substrate, and conditions in which there is no external pressurization.

FIG. 1n shows a structure of a cathode protection film of a lithium metal battery according to another embodiment.

Referring to this, the particles 13 in the protective film are interconnected, and the pores between the particles 13 are filled with a crosslinked polymerizable oligomer. The crosslinked product of the polymerizable oligomer has a structure filled with not less than 85%, for example, not less than 90%, such as not less than 95%, for example, not less than 98%, for example, not less than 98% If the particles comprise a block copolymer, the interconnected structure is more robust.

The protective film having the above-described structure has a high strength network and is excellent in lithium ion guiding effect, thereby effectively suppressing lithium resin phase growth.

In a lithium metal battery according to an embodiment, when the lithium negative electrode according to an embodiment is employed, the lithium electrodeposited density may be a lithium metal battery having no protective film (that is, a lithium metal battery employing bare lithium metal as a negative electrode) Lt; / RTI &gt; When a lithium negative electrode according to an embodiment is used in comparison with a lithium metal battery employing a lithium negative electrode according to an embodiment of the lithium metal battery in which lithium metal is not provided with a protective film, the rate of increase of the electrodeposited density of lithium is 50% For example greater than or equal to 55%, such as greater than or equal to 58%, such as between 50 and 75%, such as between 50 and 60%. The reason why the electrodeposition density is greatly improved is that the lithium negative electrode employs a protective film having high strength. Here, the Young's modulus of the protective film is 25 to 10 ⁶ Pa or more, for example, 6 to 8 GPa.

When the Young's modulus of the protective film is in the above range, the function of suppressing the volume change of the negative electrode generated during charging and discharging is excellent, and the attacked part due to the dendrite formed on the surface of the lithium metal is less likely to form a short.

The interface resistance between the lithium metal electrode derived from the Nyquist plot obtained from the impedance measurement and the protective film is reduced by 10% or more at 25 DEG C as compared with the bare lithium metal. When the electrolyte according to one embodiment is used as a protective layer of a lithium metal electrode, the interfacial resistance is reduced as compared with the case where the lithium metal electrode alone is used, so that the interfacial property is excellent. Also, the cathode has an oxidation current or a reduction current of 0.05 mA / cm ² or less in a voltage range of 0.0 to 6.0 V versus a lithium metal.

Further, when the protective film according to one embodiment is used, there is substantially no swelling problem of the battery after repeated charge and discharge. The thickness of the lithium metal battery employing the protective film is 20 to 30 占 퐉, for example, 22 to 27 占 퐉, which is 20% or more, for example, 40% or more of the bare lithium metal, Or more, specifically, 40 to 60%.

Figures 9a-9c illustrate microspheres disposed on a lithium metal surface at a lithium anode for a lithium metal battery according to one embodiment.

Referring to this, a micro-sphere 13 having a diameter of 3 탆 is disposed on the lithium metal electrode 11. 9A to 9C, the length of the lithium metal electrode 11 is about 5.4 mu m. And

In Figures 9a, 9b and 9c a is for example about 1.2 탆, 0.9 탆 and 0.5 탆, respectively. In this case, the regions in which the liquid electrolyte of the protective film is in direct contact with the lithium metal electrode are about 33.3%, 50%, and 72.2% in FIGS. 9A, 9B and 9C, respectively.

A method of manufacturing a negative electrode for a lithium metal battery according to an embodiment will be described below.

First, a composition for forming a protective film is prepared by mixing particles having a size exceeding 1 탆 and a size of 100 탆 or less and a solvent.

When a protective film is formed using the composition for forming a protective film, a composition for forming a protective film is applied on the upper surface of a lithium metal electrode and then dried to form a protective protective film containing particles.

As the solvent, tetrahydrofuran, N-methylpyrrolidone and the like can be used. The content of the solvent is 100 to 5000 parts by weight based on 100 parts by weight of the particles.

An ion conductive polymer may be further added to the protective film forming composition.

The composition for forming a protective film may include at least one selected from an ionic liquid and a polymeric ionic liquid; And a lithium salt may be further added.

The above-mentioned coating method can be used as long as it is a commonly available method for forming a protective film. For example, methods such as spin coating, roll coating, curtain coating, extrusion, casting, screen printing, inkjet printing, doctor blading and the like can be used.

Drying is carried out at 20 to 25 ° C. Drying proceeds at a low temperature as described above, so that deformation of the lithium metal electrode does not occur. A protective film having a monodispersed single layer structure can be formed by directly coating a composition for forming a protective film on a lithium metal electrode, thereby significantly improving the film processability. Such a protective film has excellent mechanical strength and improved ionic conductivity.

The electrode for a lithium metal battery can be manufactured through a process of coating and drying a composition containing a polymerizable oligomer and a solvent on a preliminary protective film formed and dried according to the above process. The process of applying the composition containing the polymerizable oligomer and the solvent may be carried out in one step or in several steps in two or more steps. The application process may be spin coating, roll coating, curtain coating, extrusion, casting, screen printing, inkjet printing, doctor blading, or the like.

Instead of the above coating process, the preliminary protective film may be dipped in a composition containing a polymerizable oligomer and a solvent.

As the solvent in the composition containing the polymerizable oligomer and the solvent, tetrahydrofuran, N-methylpyrrolidone, etc. may be used. The content of the solvent is 100 to 5000 parts by weight based on 100 parts by weight of the polymerizable oligomer. And the content of the polymerizable oligomer in the composition containing the polymerizable oligomer and the solvent is, for example, 20 to 50% by weight. The content of the polymerizable oligomer is, for example, 10 to 40 parts by weight based on 100 parts by weight of particles having a size of more than 1 탆 and not more than 100 탆. The viscosity of the composition containing the polymerizable oligomer and the solvent is preferably not more than 10 cP , For example, in the range of 0.1 to 10 cP, so that it gets wet between the particles of the protective film during casting to occupy a space between the particles.

The content of the polymerizable oligomer in the composition containing the polymerizable oligomer and the solvent is 10 to 40 parts by weight based on 100 parts by weight of the particles. When the content of the polymerizable oligomer is in the above range, a crosslinked product of the polymerizable oligomer is disposed in the space between the particles, so that the strength of the protective film can be kept high.

In the above-described method of manufacturing a negative electrode, particles are laminated on a preliminary protective film by using a composition containing particles to form a preliminary protective film, and a composition containing a polymerizable oligomer and a solvent is cast on the preliminary protective film. A negative electrode for a lithium metal battery is produced.

The anode according to one embodiment can form a protective film by a one-step process using a composition containing particles and a polymerizable oligomer in addition to the above-described production method.

The crosslinking reaction of the polymerizable oligomer can proceed through the process of applying the composition containing the above-mentioned polymerizable oligomer and the solvent on the lithium metal electrode containing the particles and drying the polymerizable oligomer. The drying is carried out in a temperature range that does not cause deformation of the lithium metal electrode including the lithium metal or the lithium metal alloy. The drying can be carried out, for example, at 20 to 40 占 폚. During the drying process, the thermal crosslinking reaction of the polymerizable oligomer can proceed. In the thermal crosslinking reaction, a thermal polymerization initiator may be used.

According to another embodiment, it is also possible to carry out a crosslinking reaction of the polymerizable oligomer by irradiating light at 20 to 40 캜. At this time, UV light is used as light.

A photopolymerization initiator is used in the crosslinking reaction in which the light is irradiated. The photopolymerization initiator

Any compound capable of forming a radical by light such as ultraviolet rays can be used without limitation of its constitution. Examples of the photopolymerization initiator include 2-hydroxy-2-methyl-1-phenyl-propan-1-one (HMPP), benzoin ether, dialkyl acetophenone, At least one member selected from the group consisting of hydroxyl alkylketone, phenyl glyoxylate, benzyl dimethyl ketal, acyl phosphine and alpha-aminoketone, Can be used. For example, 2,4,6-trimethyl-benzoyl-trimethyl phosphine oxide may be used as the acylphosphine.

As the thermal polymerization initiator, at least one selected from persulfate-based initiators, azo-based initiators, initiators consisting of hydrogen peroxide and ascorbic acid can be used. Specifically, examples of persulfate-based initiators include sodium persulfate (Na2S2O8), potassium persulfate (K2S2O8), ammonium persulfate (NH4) 2S2O8, and the like. Azo Examples of the initiator include 2, 2-azobis (2-amidinopropane) dihydrochloride, 2,2-azobis- (N, N-dimethylene) isobutane Azobis- (N, N-dimethylene) isobutyramidine dihydrochloride, 2- (carbamoyl azo) isobutylonitrile, 2, 2-azobis Azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride), 4,4-azobis- ( 4-azobis- (4-cyanovaleric acid), and the like.

The photopolymerization initiator or the thermal polymerization initiator may be contained in an amount of 0.005 to 5.0 parts by weight based on 100 parts by weight of the polymerizable oligomer. When the content of the photopolymerization initiator or the thermal polymerization initiator is in the above range, the reactivity of the polymerization reaction is excellent.

The drying process may be followed by a rolling process. The porosity and pore size in the protective film can be changed by the rolling process. And the current density and electrodeposition density of the electrode finally obtained through the rolling process can be further improved.

The rolling process can be carried out under the same process conditions as the conventional battery manufacturing process. The rolling process is carried out using, for example, a pressure of 1 to 1.5 kgf / cm.

The oxidation current or the reduction current is 0.05 mA / cm ² or less in a voltage range of 0.0 V to 6.0 V versus lithium metal. The protective film may be electrochemically stable with respect to lithium at a voltage range of 0 V to 6.0 V, for example, a voltage range of 0 V to 5.0 V, specifically, 0 V to 4.0 V. The protective film according to one embodiment can be applied to an electrochemical device operated at a high voltage by having an electrochemically stable wide voltage window.

The particles of the protective film may be organic particles. The organic particles include, for example, polystyrene or poly (styrene-divinylbenzene) copolymers.

The particles of the protective film may be inorganic particles. The above-mentioned inorganic particles include, for example, _{SiO 2, TiO 2, ZnO,} Al 2 O 3, or BaTiO _3.

The particles of the protective film may be organic particles. The organic or inorganic particles are at least one selected from, for example, silsesquioxane having a cage structure and metal-organic framework (MOF).

The silsesquioxane of the cage structure may be, for example, Polyhedral Oligomeric Silsesquioxane (POSS). There are no more than eight silicones present in such POSS, for example six or eight. The silsesquioxane having a cage structure may be a compound represented by the following formula (3).

(3)

^{_{Si k O 1 .5k (R 1}} ) a (R 2) b (R 3) c

In the above formula R ¹ , R ² , and R ³ are independently of each other hydrogen,

A substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C2-C30 alkenyl group, a substituted or unsubstituted C2-C30 alkynyl group, A substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C6-C30 aryloxy group, a substituted or unsubstituted C2-C30 heteroaryl group, a substituted or unsubstituted C4-C30 carbon ring Group, or a silicon-containing functional group.

The range of 0 <a <20, 0 <b <20, 0 <c <20, k = a + b + c and a and b c in the above formula 3 is selected to satisfy 6?

The silsesquioxane of the cage structure may be a compound represented by the following formula (4) or a compound represented by the following formula (5).

 [Chemical Formula 4]

In the general formula (4), R _{1 to} R ₈ independently represent hydrogen, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C2-C30 Substituted or unsubstituted C2-C30 alkynyl group, substituted or unsubstituted C6-C30 aryl group, substituted or unsubstituted C6-C30 aryloxy group, substituted or unsubstituted A C2-C30 heteroaryl group, a substituted or unsubstituted C4-C30 carbon ring group, or a silicon-containing functional group.

 [Chemical Formula 5]

In the formula 5, R ₁ -R ₆ are independently hydrogen, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C2-C30 to each other Substituted or unsubstituted C2-C30 alkynyl group, substituted or unsubstituted C6-C30 aryl group, substituted or unsubstituted C6-C30 aryloxy group, substituted or unsubstituted A C2-C30 heteroaryl group, a substituted or unsubstituted C4-C30 carbon ring group, or a silicon-containing functional group.

According to one embodiment, the silsesquioxane of the cage structure is R _{1 -} R ₇ is a heptathobutyl group. The silsesquioxane of the cage structure may be, for example, heptaisobutyl-t8-silsesquioxane.

The metal-organic skeleton structure is a porous crystalline compound in which a metal ion of group 2 to 15 or a metal ion cluster of group 2 to 15 is formed by a chemical bond with an organic ligand.

The organic ligand means an organic group capable of chemical bonding such as coordination bond, ionic bond or covalent bond. For example, the organic ligand is an organic group having two or more sites capable of binding to the metal ion described above, A structure can be formed.

The Group 2 to Group 15 metal ions may be at least one selected from the group consisting of Co, Ni, Mo, W, Ru, Os, Cd, beryllium, (Ba), Sr, Fe, Mn, Cr, V, Al, Ti, Zr, Zr, (Pt), copper (Cu), zinc (Zn), magnesium (Mg), hafnium (Hf), Nb, tantalum (Ta), Re, rhodium (Rh), iridium (Ir), palladium , Ag, Sc, Y, In, Thl, Si, Ge, Sn, Pb, As, Sb) and bismuth (Bi), and the organic ligand is at least one selected from aromatic dicarboxylic acid, aromatic tricarboxylic acid, imidazole compound, tetrazole compound, 1,2,3- A sulfonic acid, an aromatic phosphoric acid, an aromatic sulfinic acid, an aromatic phosphinic acid, a bipyridine, an amino group, an imino group, an acyl group, A compound having at least one functional group selected from the group consisting of a methine group, a methane group, a methane group, a methane dithio acid (-CS ₂ H) group, a methane dithioate anion (-CS ₂ ^- ) group, a pyridine group and a pyrazine group.

Examples of the above aromatic dicarboxylic acid or aromatic tricarboxylic acid include benzene dicarboxylic acid, benzenetricarboxylic acid, biphenyldicarboxylic acid and triphenyldicarboxylic acid.

The above-mentioned organic ligands may specifically be a group derived from a compound represented by the following formula (6).

[Chemical Formula 6]

The metal-organic skeleton structure can be, for example, Ti ₈ O ₈ (OH) ₄ [O ₂ CC ₆ H ₄ -CO ₂ ] _6, Cu (bpy) (H ₂ O) ₂ (BF ₄ ) ₂ = 4, 4'-bipyridine}, Zn 4 O (O 2 CC 6 H 4 -CO 2) 3 (Zn-terephthalic acid-MOF, Zn-MOF) or _{Al (OH) {O 2 CC} 6 H 4 -CO ₂ }.

The protective film may be formed of a material selected from the group consisting of i) silsesquioxane having a cage structure, metal-organic framework (MOF), Li _{1 + x + y} Al _x Ti _{2 - x} Si _y P _{3 - y} O ₁₂ (0 <x <2, 0? Y <3), BaTiO ₃ , Pb (Zr _p Ti _1-p ) O ₃ (0 _{? P? 1} ) (PZT), Pb _{1 - x} La _x Zr _{1 - y} Ti _{y O 3 (PLZT) (O≤x} <1, O≤y <1), Pb (Mg 3 Nb 2/3) O 3 -PbTiO 3 (PMN-PT), HfO 2, SrTiO 3, SnO 2, CeO _{2, Na 2 O, MgO,} NiO, CaO, BaO, ZnO, ZrO 2, y 2 O 3, Al 2 O 3, TiO 2, SiO 2, SiC, lithium phosphate _{(Li 3 PO 4), Li} x Ti y _{(PO 4) 3 (lithium titanium} phosphate, 0 <x <2,0 <y <3), Li x Al y Ti z (PO 4) 3 (lithium aluminum titanium phosphate, 0 <x <2, 0 <y < 1, 0 <z <3), Li _{1 + x + y} (Al _p Ga _{1 -p} ) _x (Ti _q Ge _{1 -q} ) _2-x Si _y P _{3 -y} O ₁₂ 0 < y < 1), Li _x La _y TiO ₃ (0 <x <2, 0 <y <3), LixGeyPzSw (lithium germanium thiophosphate, <z <1, 0 <w <5), \ Li x N y (lithium nitride, 0 <x <4, 0 <y <2), Li x Si y S z (SiS 2 based glass, 0≤x < 3,0 <y <2, 0 < z <4), Li x P y S z (P 2 S 5 based glass, 0≤x <3, 0 <y <3, 0 <z <7), Li 2 O, LiF, LiOH, Li ₂ CO ₃ , LiAlO ₂ , Li ₂ O-Al ₂ O ₃ -SiO ₂ -P ₂ O ₅ -TiO ₂ -GeO ₂ , Li _{3 + x} La ₃ M ₂ O ₁₂ Te, Nb, or Zr) (0? X? 5) At least one particle selected from the group consisting of luer; Or ii) the particles have cross-linkable functional groups and may have structures cross-linked by these functional groups.

The crosslinkable functional group may be any functional group that can be crosslinked, and examples thereof include an acrylate group, a methacrylate group, and an epoxy group.

When a crosslinkable functional group is present on the particle surface, the particles are covalently linked to each other, and the mechanical strength of the protective layer made of such particles can be further improved.

The ionic liquid refers to a salt in a liquid state or a room-temperature molten salt at room temperature, which has a melting point below room temperature and is composed of only ions. The ionic liquid may be selected from the group consisting of i) an ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, And at least one cation selected from the group consisting of BF ₄ ^- , PF ₆ ^- , AsF ₆ ^- , SbF ₆ ^- , AlCl ₄ ^- , HSO ₄ ^- , ClO ₄ ^- , CH ₃ SO ₃ ^- , CF _{3 ^{CO 2 -, Cl -, Br}} -, I -, SO 4 -, CF 3 SO 3 -, (FSO 2) 2 N -, (C 2 F 5 SO 2) 2 N -, (C 2 F 5 SO 2 ) (CF ₃ SO ₂ ) N ^- , and (CF ₃ SO ₂ ) ₂ N ^- .

Ionic liquids include, for example, N-methyl-N-propylpyrrolidinium bis (trifluoromethanesulfonyl) imide N-butyl-N-methylpyrrolidiumbis (trifluoromethylsulfonyl) 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) amide and 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) amide.

The content of the ionic liquid is 5 to 40 parts by weight, for example, 7.5 to 30 parts by weight, for example, 10 to 20 parts by weight, based on 100 parts by weight of the particles of the protective film. When the content of the ionic liquid is within the above range, a protective film excellent in ionic conductivity and mechanical properties can be obtained.

(IL / Li) of the ionic liquid (IL) / lithium ion (Li) is 0.1 to 2.0, for example, 0.2 to 1.8, . The polymer electrolyte having such a molar ratio has excellent lithium ion mobility and ion conductivity as well as excellent mechanical properties and can effectively inhibit lithium dendrite growth on the surface of a negative electrode.

The polymeric ionic liquid may be obtained by polymerizing an ionic liquid monomer, or may be a polymeric compound. Such a polymeric ionic liquid has a high solubility in an organic solvent and has an advantage that ionic conductivity can be further improved when added to an electrolyte.

In the case of obtaining a polymeric ionic liquid by polymerizing the above-mentioned ionic liquid monomer, the polymeric reaction product is washed and dried, and then anion substitution reaction is carried out to obtain an appropriate anion capable of imparting solubility to the organic solvent do.

The polymeric ionic liquid according to one embodiment may be selected from the group consisting of i) ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, At least one cation selected from the group consisting of BF ₄ ^- , PF ₆ ^- , AsF ₆ ^- , SbF ₆ ^- , AlCl ₄ ^- , HSO ₄ ^- , ClO ₄ ^- , CH _{3 ^{SO 3 -, CF 3 CO 2}} -, (CF 3 SO 2) 2 N -, (FSO 2) 2 N -, Cl -, Br -, I -, SO 4 -, CF 3 SO 3 -, (C 2 ^{_{F 5 SO 2) 2 N -}} , (C 2 F 5 SO 2) (CF 3 SO 2) N -, NO 3 -, Al 2 Cl 7 -, (CF 3 SO 2) 3 C -, (CF 3) ^{_{2 PF 4 -, (CF 3}} ) 3 PF 3 -, (CF 3) 4 PF 2 -, (CF 3) 5 PF -, (CF 3) 6 P -, SF 5 CF 2 SO 3 -, SF 5 CHFCF ^{_{2 SO 3 -, CF 3 CF}} 2 (CF 3) 2 CO -, (CF 3 SO 2) 2 CH -, (SF 5) 3 C -, (O (CF 3) 2 C 2 (CF 3) 2 O ) ₂ PO-. &Lt; ^/ RTI &gt;

According to another embodiment, the polymeric ionic liquid can be prepared by polymerizing an ionic liquid monomer. The ionic liquid monomer preferably has a functional group capable of polymerizing with a vinyl group, an allyl group, an acrylate group, a methacrylate group and the like, and is selected from the group consisting of ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, The anion may have at least one cation selected from the group consisting of a pyrazolium series, an oxazolium series, a pyridazinium series, a phosphonium series, a sulfonium series, a triazolium series and mixtures thereof.

Examples of the ionic liquid monomer include 1-vinyl-3-ethylimidazolium bromide and a compound represented by the following general formula (7) or (8).

(7)

[Chemical Formula 8]

Examples of the above polymeric ionic liquid include a compound represented by the following formula (9) or a compound represented by the following formula (10).

[Chemical Formula 9]

Wherein R ₁ and R ₃ are independently selected from the group consisting of hydrogen, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C2-C30 alkenyl group, a substituted or unsubstituted C2-C30 A substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C2-C30 heteroaryl group, and a substituted or unsubstituted C4-C30 carbon ring group. In the formula (10), R ₂ represents a chemical bond or represents a C1-C30 alkylene group, a C6-C30 arylene group, a C2-C30 heteroarylene group or a C4-C30 divalent carbon ring group,

X ^- represents an anion of the ionic liquid,

and n is 500 to 2800.

[Chemical formula 10]

In the formula 10 ^Y-X is of formula (9) ^- is defined in the same manner as, n is from 500 to 2800.

Y ^- in formula (10) is, for example, bis (trifluoromethanesulfonyl) imide (TFSI), bis (fluorosulfonyl) imide, BF ₄ or CF ₃ SO ₃ .

Polymeric ionic liquids include, for example, poly (1-vinyl-3-alkylimidazolium), poly (1-allyl-3-alkylimidazolium), poly (1- (methacryloyloxy- and selected from imidazolium) ^{_{cation, CH 3 COO -, CF 3}} COO -, CH 3 SO 3 -, CF 3 SO 3 -, (CF 3 SO 2) 2 N -, (FSO 2) 2 N -, ( ^{_{CF 3 SO 2) 3 C -}} , (CF 3 CF 2 SO 2) 2 N -, C 4 F 9 SO 3 -, C 3 F 7 COO - , and _{(CF 3 SO 2) (CF} 3 CO) N - from Selected anions.

The compound represented by the above formula (10) includes polydiallyldimethylammonium bis (trifluoromethanesulfonyl) imide.

According to another embodiment, the polymeric ionic liquid may comprise a low molecular weight polymer, a thermally stable ionic liquid and a lithium salt. The low molecular weight polymer may have an ethylene oxide chain. The low molecular weight polymer may be glyme. Examples of the glyme include polyethylene glycol dimethyl ether (polyglyme), tetraethylene glycol dimethyl ether (tetraglyme), and triethylene glycol dimethyl ether (triglyme).

The weight average molecular weight of the low molecular weight polymer is 75 to 2000 Daltons, for example 100 to 1000 Daltons, for example 250 to 500 Daltons. And the thermally stable ionic liquid is as defined in the above ionic liquid. The lithium salt may be any of the compounds in the case where the alkali metal is lithium among the above alkali metal salts.

The protective film may further include an oligomer. The oligomer is at least one selected from the group consisting of polyethylene glycol dimethyl ether and polyethylene glycol diethyl ether. The weight average molecular weight of the oligomer is from 200 to 2,000 Daltons, for example from 300 to 1800 Daltons, for example from 400 to 1500 Daltons, and the oligomer content is from 5 to 50 parts by weight, based on 100 parts by weight of the protective film, 10 to 40 parts by weight, for example, 10 to 30 parts by weight. When the oligomer is added in this manner, the film forming property, the mechanical property, and the ionic conductivity of the protective film are superior.

The ionic conductivity of the protective film may be 1 X 10 ^-4 S / cm or more, for example, 5 × 10 ^-4 S / cm or more, specifically 1 × 10 ^-3 S / cm or more at about 25 ° C.

The lithium metal battery may include, for example, a lithium air battery, a lithium ion battery, a lithium polymer battery, and a lithium sulfur battery.

The protective film according to one embodiment is suitable as a high-voltage lithium metal battery protective film. Here, "high voltage" refers to a case where the charging voltage is in the range of 4.0V to 5.5V.

According to another aspect, there is provided a lithium metal battery including an anode, a cathode for a lithium metal battery according to an embodiment, and an electrolyte interposed therebetween.

The electrolyte may be a mixed electrolyte type including two or more selected from a liquid electrolyte, a solid electrolyte, a gel electrolyte, and a polymer ionic liquid. The lithium metal battery may further include a separator.

The lithium metal battery may further include at least one selected from a liquid electrolyte, a polymer ionic liquid, a solid electrolyte, and a gel electrolyte.

At least one selected from a liquid electrolyte, a polymeric ionic liquid, a gel electrolyte, and a solid electrolyte may be interposed between the anode and the cathode. As described above, the conductivity and mechanical properties of the electrolyte can be further improved by further including at least one selected from a liquid electrolyte, a polymeric ionic liquid, a solid electrolyte, and a gel electrolyte.

The gel electrolyte is an electrolyte having a gel form, and any of those known in the art can be used. The gel electrolyte may contain, for example, a polymer and a polymeric ionic liquid. The polymer may be, for example, a solid graft (block) copolymer electrolyte.

The solid electrolyte can be an organic solid electrolyte or an inorganic solid electrolyte.

Examples of the organic solid electrolyte include a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, a polyelectrolytic lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene chloride, And the like can be used.

The inorganic solid _{electrolyte, Li 3 N, LiI, Li} 5 NI 2, Li 3 N-LiI-LiOH, Li 2 SiS 3, Li 4 SiO 4, Li 4 SiO 4 -LiI-LiOH, Li 3 PO 4 - _{Li 2 S-SiS 2, Cu} 3 N, LiPON, Li 2 S.GeS 2 .Ga 2 S 3, Li 2 O.11Al 2 O 3, (Na, Li) 1+ x Ti 2 - x Al x (PO ₄ ) ₃ (0.1? _X ? 0.9), Li _{1 + x} Hf _{2 - x} Al _x (PO ₄ ) ₃ (0.1? X? 0.9), Na ₃ Zr ₂ Si ₂ PO ₁₂ , Li ₃ Zr ₂ Si ₂ PO ₁₂ , Na ₅ ZrP ₃ O ₁₂ , Na ₅ TiP ₃ O ₁₂ , Na ₃ Fe ₂ P ₃ O ₁₂ , Na ₄ NbP ₃ O ₁₂ , Na-Silicates, Li _{0 . 3} La _{0 . 5} TiO ₃ , Na ₅ MSi ₄ O ₁₂ (M is a rare earth element such as _{Nd, Gd, Dy) Li 5} ZrP 3 O 12, Li 5 TiP 3 O 12, Li 3 Fe 2 P 3 O 12, Li 4 NbP 3 O 12, Li 1 + x (M, Eu, Gd, Tb, Dy, Ho, Er, Ga) _x (Ge _1-y Ti _y ) _{2 -x} (PO ₄ ) ₃ (x? 0.8, _{0? Y} ? 1.0, M is Nd, Tm or Yb), Li _{1 + x + y} Q _x Ti _{2 -x} Si _y P _{3 -y} O ₁₂ (0 <x? 0.4, 0 < _y ? 0.6, Q is Al or Ga), Li ₆ BaLa ₂ Ta ₂ O ₁₂ , Li ₇ La ₃ Zr ₂ O ₁₂ , Li ₅ La ₃ Nb ₂ O ₁₂ , Li ₅ La ₃ M ₂ O ₁₂ (M is Nb, Ta), Li _{7 + x} A _x La _{3 - x} Zr ₂ O ₁₂ (0 < x < 3, A is Zn).

The protective film according to one embodiment may include at least one selected from an ionic liquid, a metal salt containing a Group 1 or 2 element and a nitrogen-containing additive, boron nitride, or a mixture thereof.

Wherein the metal salt containing the Group 1 element or the Group 2 element is at least one metal salt containing at least one selected from Cs, Rb, K, Ba, Fr, Ca, Na and Mg, (Li ₃ N), inorganic nitrate, organic nitrate, inorganic nitrite, organic nitrite, organic nitro compound, organic nitric compound, NO compound and lithium nitride Lt; / RTI &gt;

At least one selected from the group consisting of a metal salt containing a group I or II element and a nitrogen-containing additive is insoluble in an organic solvent of a liquid electrolyte. In view of solubility characteristics, when a protective film is used which is stably present only on the surface of a lithium metal anode and is limited in at least one of mobility and a nitrogen-containing additive selected from the group consisting of metal salts containing Group 1 or Group 2 elements, And does not interfere with the movement.

In addition, the metal of the metal salt containing the Group 1 or Group 2 element has a larger atomic size than that of lithium, and if it is contained in the protective layer, the metal stain hindrance effect causes a lithium dendrite Can be inhibited from growing. The metal cation (for example, Cs or rubidium ion) of the metal salt has a small effective reduction potential as compared with the reduction potential of lithium ion, so that the metal salt is reduced or applied during the lithium deposition process Without process, metal cations form a positive charge electrostatic shield around the initial growth tip of the protuberance on the surface of the lithium metal cathode. When such a positive electrostatic shield is formed, the growth of lithium dendrites on the surface of the lithium metal cathode can be effectively inhibited. As described above, the content of the metal salt is important for the metal salt to have a small effective reduction potential as compared with the reduction potential of lithium. The content of the metal salt is controlled in the range of 0.1 to 100 parts by weight, for example, 1 to 75 parts by weight, for example, 10 to 50 parts by weight, based on 100 parts by weight of the protective film.

In addition, the protective film is excellent in mechanical strength and flexibility, so that the effect of suppressing the formation of lithium dendrite is excellent, and an ion conductive film having high ion conductivity is formed between the lithium metal anode and the protective film. The ion conductive film reduces the interfacial resistance between the lithium metal cathode and the protective film by increasing the ionic conductivity and the lithium ion mobility of the protective film. The ion conductive film contains, for example, lithium nitride (Li ₃ N).

In addition, the protective layer improves the electrophoresis morphology of the lithium metal cathode by chemically improving the lithium desorption / desorption process to increase the electrodeposition density on the surface of the lithium metal cathode, Thereby improving ion mobility. As described above, at least one selected from the metal salt and the nitrogen-containing additive is present in a protective film on the surface of the lithium metal anode, and at least one selected from the metal salt and the nitrogen-containing additive is dispersed in the liquid electrolyte or approaches the anode, Thereby preventing the reaction from occurring. As a result, it is possible to produce a lithium metal battery with improved rateing performance and life.

The nitrogen containing additive contained in the protective film can be, but not limited to, inorganic nitrate, organic nitrate, inorganic nitrite, organic nitrite, organic nitro compound, organic An organic compound, an organic compound, a nitric compound, an NO compound, and lithium nitride (Li ₃ N).

The inorganic nitrate is at least one selected from the group consisting of lithium nitrate, potassium nitrate, cesium nitrate, barium nitrate and ammonium nitrate, and the organic nitrate is, for example, a dialkyl imidazolium nitride Is at least one selected from the group consisting of guanidine nitrate, ethylnitrite, propylnitrite, butylnitrite, pentylnitrite, and octylnitrite. And the organic nitrite is at least one selected from the group consisting of ethylnitrite, propylnitrite, butylnitrite, pentylnitrite, and octylnitrite.

Examples of the organic nitro compound include at least one selected from the group consisting of nitromethane, nitropropane, nitrobutane, nitrobenzene, dinitrobenzene, nitrotoluene, dinitrotoluene and nitropyridine. And the N-O compound is at least one selected from the group consisting of, for example, pyridine N-oxide, alkylpyridine N-oxide, and tetramethylpiperidine N-oxyl (TEMPO).

In the protective film according to another embodiment, the nitrogen-containing additive is at least one selected from LiNO ₃ and Li ₃ N, and the metal salt containing the group I or II element is cesium bistrifluoromethylsulfonylimide (CsTFSI), and _{CsNO 3, CsPF 6, CsFSI,} CsAsF 6, CsClO 4, or CsBF _4, for example, be CsTFSI.

The content of at least one selected from a metal salt containing a group 1 or group 2 element and a nitrogen-containing additive in the protective film is 0.1 to 100 parts by weight, for example, 0.1 to 30 parts by weight, based on 100 parts by weight of the particles. When the content of at least one selected from the group consisting of metal salts containing Group 1 or Group 2 elements and nitrogen containing additives is within the above range, the effect of inhibiting the growth of lithium dendrites and the effect of reducing the interface resistance between the lithium metal anode surface and the protective film, Can be produced.

According to one embodiment, the protective film may comprise only a metal salt containing a group I or II element. The content of the metal salt containing a Group 1 or Group 2 element is 0.1 to 100 parts by weight, for example, 0.1 to 50 parts by weight, for example, 0.1 to 30 parts by weight, based on 100 parts by weight of the particles.

According to another embodiment, the protective film may contain only a nitrogen-containing additive. At this time, the content of the nitrogen-containing additive is 0.1 to 100 parts by weight, for example, 0.1 to 50 parts by weight, for example, 0.1 to 30 parts by weight, based on 100 parts by weight of the particles.

The protective film may contain, for example, both a metal salt containing a Group 1 or 2 element and a nitrogen-containing additive. In this case, the content of the metal salt containing a Group 1 or Group 2 element is 0.01 to 99.99 parts by weight, for example, 0.1 to 50 parts by weight, for example, 0.1 to 30 parts by weight, based on 100 parts by weight of the particles, Is from 0.01 to 99.99 parts by weight, for example, from 0.1 to 50 parts by weight, for example, from 0.1 to 30 parts by weight, based on 100 parts by weight of the particles.

The weight ratio of the metal salt containing the Group 1 or Group 2 element to the nitrogen containing additive in the protective film according to one embodiment is 1: 9 to 9: 1, for example, 1: 2 to 2: 1, specifically 1: 1 . When the mixing ratio by weight of the metal salt containing a Group 1 or Group 2 element and the nitrogen-containing additive is within the above range, the electrodeposition density on the surface of the lithium metal anode and the lithium ion mobility property in the electrolyte are excellent, .

The lithium metal electrode may be a lithium metal electrode or a lithium metal alloy electrode, and a liquid electrolyte containing at least one selected from an organic solvent, an ionic liquid and a lithium salt may be further interposed between the cathode and the anode.

When a negative electrode according to an embodiment is employed, a lithium metal battery having improved capacity retention rate can be manufactured. Such a lithium metal battery has high voltage, capacity, and energy density and is widely used in the fields of portable telephones, notebook computers, batteries for power generation facilities such as wind power and solar power, electric vehicles, uninterruptible power supplies, and household batteries.

Figures 1G-1J schematically illustrate the structure of a lithium metal battery according to one embodiment.

As shown in FIG. 1G, the lithium metal battery has a structure in which an electrolyte 24 is interposed between the anode 21 and another cathode 22 in one embodiment. A protective film (23) is included between the electrolyte (24) and the cathode (22). The electrolyte (24) may further include at least one selected from a liquid electrolyte, a polymer ionic liquid, a solid electrolyte, and a gel electrolyte. The lithium metal battery may further include a separator.

As the protective film 23 described above is disposed on at least a part of the cathode 22, the cathode surface can be stabilized electrochemically while being mechanically stabilized. Therefore, the formation of dendrites on the surface of the negative electrode during charging and discharging of the lithium metal battery can be suppressed, and the interface stability between the negative electrode and the electrolyte is improved. Therefore, the cycle characteristics of the lithium metal battery can be improved.

The electrolyte 24 may have a two-layer structure in which a liquid electrolyte 24a and a solid electrolyte 24b are sequentially stacked as shown in FIG. 1H. Here, the liquid electrolyte may be disposed adjacent to the protective film 23. This lithium metal battery has a stacking order of a negative electrode / a protective film / an electrolyte (liquid electrolyte / solid electrolyte) / an anode.

Referring to FIG. 1I, the lithium metal battery according to one embodiment may use a separator 24c. The separator may be a single layer film made of polyethylene, polypropylene, polyvinylidene fluoride or a combination thereof, or a multilayer film of two or more thereof. The separator may be a polyethylene / polypropylene double layer separator, a polyethylene / polypropylene / polyethylene triple layer separator , A polypropylene / polyethylene / polypropylene three-layer separator, or the like can be used. The separator may further include an electrolyte containing a lithium salt and an organic solvent.

As shown in FIG. 1J, the lithium metal battery according to one embodiment may be arranged with the liquid electrolyte 24a. Here, the composition of the liquid electrolyte, which may be contained in the protective film 23, may be the same as or different from that of the liquid electrolyte.

1K is a schematic view of a lithium metal battery structure according to another embodiment.

The lithium metal battery 30 includes a battery case 34 that includes an anode 31, a cathode 32 according to one embodiment, and accommodates them.

In Figures 1G-1K, the anode may be a porous anode. The porous anode includes pores which contain pores or which do not exclude the formation of an anode intentionally so that the liquid electrolyte can be permeated into the inside of the anode by capillary phenomenon or the like.

For example, the porous anode includes a cathode obtained by coating and drying a cathode active material composition comprising a cathode active material, a conductive agent, a binder and a solvent. The thus obtained positive electrode may contain pores existing between the positive electrode active material particles. Such a porous anode may be impregnated with a liquid electrolyte.

According to another embodiment, the anode may comprise a liquid electrolyte, a gel electrolyte, or a solid electrolyte. The liquid electrolyte, the gel electrolyte, and the solid electrolyte can be used as an electrolyte of a lithium metal battery in the related art, and can be any material that does not deteriorate the cathode active material by reacting with the cathode active material during charging and discharging.

The constituent elements constituting the lithium metal battery including the negative electrode according to one embodiment and the method for manufacturing the lithium metal battery having such constituent elements will be described in detail as follows.

The positive electrode active material for producing the positive electrode may include at least one selected from the group consisting of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, and lithium manganese oxide. And any cathode active material available in the art may be used.

For example, Li _a A _{1 - b} B _b D ₂ (in the above formula, 0.90? A?? 1.8, and 0? B? 0.5); Li _a E _{1 - b} B _b O _{2 - c} D _c wherein, in the formula, 0.90? A? 1.8, 0? B? 0.5, 0? C? LiE _{2 - b} B _b O _{4 - c} D _{c where} 0? B?? 0.5, 0? _C ? 0.05; Li _a Ni _{1 -bc} Co _b B _c D _? Wherein _? 0.90 _{? A?} 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, 0 <?? _{Li a Ni 1 -b- c Co b} B c O 2 - α F α ( wherein, 0.90≤≤a≤≤1.8, 0≤≤b≤≤0.5, 0≤≤c≤≤0.05, 0 <α <2); _{Li a Ni 1 -b- c Mn b} B c D α ( in the above formula, 0.90≤≤a≤≤1.8, 0≤≤b≤≤0.5, 0≤≤c≤≤0.05, 0 <α≤≤2) ; _{Li a Ni 1 -b- c Mn b} B c O 2 - α F α ( wherein, 0.90≤≤a≤≤1.8, 0≤≤b≤≤0.5, 0≤≤c≤≤0.05, 0 <α <2); Li _a Ni _b E _c G _d O ₂ wherein 0.90? A? 1.8, 0? B? 0.9, 0? C? 0.5, and 0.001? D? 0.1. Li _a Ni _b Co _c Mn _d GeO ₂ wherein 0.90? A? 1.8, 0? B? 0.9, 0? C? 0.5, 0? D? 0.5, 0.001? E Lt; = 0.1); Li _a NiG _b O ₂ (in the above formula, 0.90?? A?? 1.8, and 0.001? _B ?? 0.1); Li _a CoG _b O ₂ wherein, in the above formula, 0.90?? A?? 1.8, and 0.001? B? Li _a MnG _b O ₂ wherein, in the above formula, 0.90?? A?? 1.8, and 0.001? B? Li _a Mn ₂ G _b O ₄ (in the above formula, 0.90? A?? 1.8, 0.001? B?? 0.1); QO _2; QS ₂ ; LiQS ₂ ; V ₂ O ₅ ; LiV ₂ O ₅ ; LiIO ₂ ; LiNiVO _4; Li _(3-f) J ₂ (PO ₄ ) ₃ (0? F?? 2); _{(0≤≤f≤≤2) Li (3-f} ) Fe 2 (PO 4) 3; A compound represented by any one of the formulas of LiFePO ₄ can be used.

In the above formula, A is Ni, Co, Mn, or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or combinations thereof; Q is Ti, Mo, Mn, or a combination thereof; I is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

As the cathode active material, for example, one selected from compounds represented by the following general formulas (11) to (14) may be used.

(11)

Li _a Ni _b Co _c Mn _d O ₂

In the above formula (11), 0.90? A? 1.8, 0? B? 0.9, 0? C? 0.5, and 0? D?

[Chemical Formula 12]

Li ₂ MnO ₃

[Chemical Formula 13]

LiMO ₂

In the above formula (12), M is Mn, Fe, Co, or Ni.

[Chemical Formula 14]

Li _a Ni _b Co _c Al _d O ₂

In the above formula (14), 0.90? A? 1.8, 0? B? 0.9, 0? C? 0.5, and 0? D?

The anode is prepared according to the following method.

A cathode active material composition in which a cathode active material, a binder and a solvent are mixed is prepared.

A conductive agent may further be added to the cathode active material composition.

The positive electrode active material composition is directly coated on the metal current collector and dried to produce a positive electrode plate. Alternatively, the cathode active material composition may be cast on a separate support, and then the film peeled from the support may be laminated on the metal current collector to produce a cathode plate.

The binder is a component that assists in bonding between the active material and the conductive agent and bonding to the current collector. Non-limiting examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoro And examples thereof include ethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber, fluorine rubber and various copolymers. The content thereof is 1 to 50 parts by weight, for example, 2 to 5 parts by weight based on 100 parts by weight of the total weight of the cathode active material. When the content of the binder is in the above range, the binding force of the active material layer to the current collector is good.

The conductive agent is not particularly limited as long as it has electrical conductivity without causing a chemical change in the battery, and examples thereof include graphite such as natural graphite and artificial graphite; Carbonaceous materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Carbon fluoride; Metal powders such as aluminum and nickel powder; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The conductive agent is used in an amount of 1 to 10 parts by weight, for example, 2 to 5 parts by weight based on 100 parts by weight of the total weight of the cathode active material. When the content of the conductive agent is in the above range, the conductivity of the finally obtained electrode is excellent.

As a non-limiting example of the solvent, N-methylpyrrolidone or the like is used.

The solvent is used in an amount of 100 to 2000 parts by weight based on 100 parts by weight of the cathode active material. When the content of the solvent is within the above range, the work for forming the active material layer is easy.

The content of the cathode active material, the conductive agent, the binder, and the solvent is a level commonly used in a lithium metal battery. Depending on the use and configuration of the lithium metal battery, one or more of the conductive agent, the binder and the solvent may be omitted.

The negative electrode may be a lithium metal thin film or a lithium metal alloy thin film as described above.

The lithium metal alloy may comprise lithium and a metal / metalloid capable of alloying with lithium. For example, the metal / metalloid capable of being alloyed with lithium may be at least one selected from the group consisting of Si, Sn, Al, Ge, Pb, Bi, Sb, Si-Y alloy (Y is an alkali metal, an alkali earth metal, (Y is an alkali metal, an alkaline earth metal, a Group 13 to Group 16 element, a transition metal, a rare earth element, or a combination element thereof, Sn is a rare earth element or a combination element thereof, Or the like). The element Y may be at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ge, P, As, Sb, Bi, Te, Po, or a combination thereof.

As the electrolyte, a separator and / or a lithium salt-containing nonaqueous electrolyte conventionally used in a lithium metal battery may be used.

The separator is made of an insulating thin film having high ion permeability and mechanical strength. The pore diameter of the separator is generally 0.01 to 10 mu m and the thickness is generally 5 to 20 mu m. As such a separator, for example, an olefin-based polymer such as polypropylene; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like is used. When a solid polymer electrolyte is used as the electrolyte, the solid polymer electrolyte may also serve as a separator.

Specific examples of the separator may include polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more thereof. The separator may be a polyethylene / polypropylene double layer separator, a polyethylene / polypropylene / polyethylene triple layer separator, a polypropylene / / Polypropylene three-layer separator, and the like.

The lithium salt-containing nonaqueous electrolyte is composed of a nonaqueous electrolyte and a lithium salt.

As the non-aqueous electrolyte, a non-aqueous electrolyte, an organic solid electrolyte, or an inorganic solid electrolyte is used.

The nonaqueous electrolytic solution includes an organic oil. These organic solvents may be used as long as they can be used as organic solvents in the art. Examples of the solvent include propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate , Fluoroethylene carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, gamma -butyrolactone, 1,3-dioxolane, 4-methyldioxolane, N, Amides, N, N-dimethylacetamide, dimethylsulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether or mixtures thereof. And an example wherein the lithium salt is, for _{example, LiPF 6, LiBF 4, LiSbF} 6, LiAsF 6, LiClO 4, LiCF 3 SO 3, Li (CF 3 SO 2) 2 N, Li (FSO 2) 2 N, LiC 4 _{F 9 SO 3, LiAlO 2,} LiAlCl 4, LiN (C x F 2x + 1 SO2) (C y F 2y + 1 SO 2) ( with the proviso that x and y are natural numbers), there is LiCl, LiI and mixtures thereof.

 For the purpose of improving the charge-discharge characteristics and the flame retardancy, non-aqueous electrolytes include, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, hexamethylphosphoamide hexamethyl phosphoramide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrroles, 2-methoxyethanol, Etc. may be added. In some cases, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further added to impart nonflammability.

The lithium metal battery according to one embodiment can be used not only for a battery cell used as a power source of a small device because of its excellent capacity and life characteristics, but also as a middle- or large-sized battery pack including a plurality of battery cells used as a power source for a medium- The battery module may also be used as a unit battery.

Examples of the medium and large-sized devices include an electric vehicle (EV) including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV) E-bike, an electric motorcycle electric power tool electric power storage device including an electric scooter (E-scooter), but the present invention is not limited thereto.

As used herein, alkyl refers to fully saturated branched or unbranched (or straight chain or linear) hydrocarbons.

Non-limiting examples of "alkyl" include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n- pentyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, n-heptyl and the like.

"Alkyl" at least one hydrogen atom of an alkyl group of a halogen atom, halogen-substituted C1-C20 (for _{example: CCF 3, CHCF 2, CH} 2 F, CCl 3 , etc.), an alkoxy of C1-C20 alkoxy, C2-C20 of A sulfamoyl group, a sulfonic acid group or a salt thereof, a phosphoric acid or a salt thereof, a C1-C20 alkyl group, a hydroxyl group, a nitro group, a cyano group, an amino group, an amidino group, a hydrazine, a hydrazone, a carboxyl group or a salt thereof, C20 alkenyl, C2-C20 alkynyl, C1-C20 heteroalkyl, C6-C20 aryl, C7-C20 arylalkyl, C6-C20 heteroaryl, C7-C20 heteroaryl An alkyl group, a C6-C20 heteroaryloxy group, or a C6-C20 heteroaryloxyalkyl group.

The term &quot; halogen atom &quot; includes fluorine, bromine, chlorine, iodine and the like.

&Quot; Alkenyl &quot; refers to branched or unbranched hydrocarbons having at least one carbon-carbon double bond. Non-limiting examples of the alkenyl group include vinyl, allyl, butenyl, isopropenyl, isobutenyl and the like, and at least one hydrogen atom of the alkenyl may be substituted with the same substituent as the alkyl group described above .

&Quot; Alkynyl &quot; refers to branched or unbranched hydrocarbons having at least one carbon-carbon triple bond. Non-limiting examples of the "alkynyl" include ethynyl, butynyl, isobutynyl, propynyl, and the like.

At least one hydrogen atom of &quot; alkynyl &quot; may be substituted with the same substituent as in the alkyl group described above.

&Quot; Aryl &quot; also includes groups wherein the aromatic ring is optionally fused to one or more carbon rings. Non-limiting examples of &quot; aryl &quot; include phenyl, naphthyl, tetrahydronaphthyl, and the like.

Also, at least one hydrogen atom in the &quot; aryl &quot; group may be substituted with the same substituent as in the case of the above-mentioned alkyl group.

&Quot; Heteroaryl &quot; means a monocyclic or bicyclic aromatic organic group containing one or more heteroatoms selected from N, O, P, or S and the remaining ring atoms carbon. The heteroaryl group may contain, for example, from 1 to 5 hetero atoms, and may include 5-10 ring members. The S or N may be oxidized to have various oxidation states.

Examples of heteroaryl include thienyl, furyl, pyrrolyl, imidazolyl, pyrazolyl, thiazolyl, isothiazolyl, 1,2,3-oxadiazolyl, 1,2,4-oxadiazolyl, , 5-oxadiazolyl, 1,3,4-oxadiazolyl group, 1,2,3-thiadiazolyl, 1,2,4-thiadiazolyl, 1,2,5-thiadiazolyl, Thiadiazolyl, isothiazol-3-yl, isothiazol-4-yl, isothiazol-5-yl, oxazol- Yl, isoxazol-3-yl, 1,2,4-triazol-5-yl, Yl, pyrid-3-yl, pyrazin-2-yl, pyrid-2-yl, , Pyrazin-4-yl, pyrazin-5-yl, pyrimidin-2-yl, pyrimidin-4-yl or pyrimidin-5-yl.

The term &quot; heteroaryl &quot; includes those where the heteroaromatic ring is optionally fused to one or more aryl, cyclyaliphatic, or heterocycle.

The &quot; carbon ring &quot; group used in the formula refers to a saturated or partially unsaturated non-aromatic monocyclic, bicyclic or tricyclic hydrocarbon group.

Examples of monocyclic hydrocarbons include cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl, and the like. Examples of bicyclic hydrocarbons are bornyl, decahydronaphthyl, bicyclo [2.1.1] hexyl, bicyclo [2.2.1] heptyl, bicyclo [2.2.1] heptenyl, or bicyclo [2.2.2] octyl. And examples of tricyclic hydrocarbons include adamantly.

A &quot; heterocycle &quot; may contain from 5 to 20, for example from 5 to 20, carbon atoms as a cyclic group containing at least one heteroatom. Wherein the heteroatom is one selected from sulfur, nitrogen, oxygen and boron.

Alkoxy, aryloxy, heteroaryloxy means alkyl, aryl and heteroaryl, respectively, attached to an oxygen atom herein.

Will be explained in more detail through the following examples and comparative examples. However, the embodiments are for illustrative purposes only and are not intended to be limiting.

Example  1: Manufacture of cathode

(EPR-PSD-3, manufactured by EPRUI) was added to anhydrous tetrahydrofuran to obtain a mixture containing 5% by weight of a block copolymer (hereinafter, abbreviated as &quot; poly (styrene-b-divinylbenzene) &Lt; / RTI &gt;

In the block copolymer, the mixing ratio of the polystyrene block and the polydivinylbenzene block was about 9: 1 by weight, and the weight average molecular weight of the poly (styrene-b-divinylbenzene) block copolymer was about 100,000 Daltons.

Lithium bis (fluorosulfonyl) imide (LiFSI) {LiN (SO ₂ F) ₂ } was added to the block copolymer-containing mixture to obtain a composition for forming a protective film. Here, the content of LiFSI was about 30 parts by weight based on 100 parts by weight of the poly (styrene-b-divinylbenzene) copolymer.

The composition for forming a protective film was coated on the upper portion of a lithium metal thin film (thickness: about 20 mu m) formed on the copper thin film with a doctor blade to a thickness of about 3 mu m.

The coated product was dried at about 25 DEG C and then dried under vacuum at about 40 DEG C for about 24 hours.

Separately, diethylene glycol diacrylate (DEGDA) was dissolved in tetrahydrofuran to prepare a 30 wt% solution. The content of DEGDA was 30 parts by weight based on 100 parts by weight of poly (styrene-b-divinylbenzene) block copolymer microspheres. The solution was cast on top of the dried product. Subsequently, the cast product was dried at about 25 DEG C for 12 hours, and then irradiated with UV at about 40 DEG C for 1 hour to obtain a solution of diethylene glycol diacrylate (hereinafter referred to as &quot; 0.0 &gt; DEGDA). &Lt; / RTI &gt; The content of the crosslinked product of diethylene glycol diacrylate (DEGDA) was 20 parts by weight based on 100 parts by weight of the poly (styrene-b-divinylbenzene) block copolymer microspheres.

Example  2-3: Preparation of cathode

A negative electrode was produced in the same manner as in Example 1 except that the thickness of the protective film was changed to about 1 탆 and 8 탆.

Example  4: Manufacture of cathode and lithium metal battery

A negative electrode having a protective film containing a cross-linked product of diethylene glycol diacrylate (DEGDA) disposed in the space between the microspheres and the microspheres was formed on the lithium metal thin film. The content of the crosslinked product of diethylene glycol diacrylate (DEGDA) was 20 parts by weight based on 100 parts by weight of the poly (styrene-b-divinylbenzene) block copolymer microspheres.

Separately, a composition for forming a positive electrode active material layer was obtained by mixing LiCoO ₂ , Super-P (Timcal Ltd.), polyvinylidene fluoride (PVdF) and N-methylpyrrolidone. The mixing weight ratio of LiCoO ₂ , the conductive agent and the PVDF in the composition for forming the positive electrode active material layer was 97: 1.5: 1.5. The content of N- methylpyrrolidone is LiCoO ₂ When 97 g was used, about 137 g was used.

The composition for forming the cathode active material layer was coated on an aluminum foil (thickness: about 15 탆), dried at 25 캜, and dried. The dried product was vacuum dried at about 110 캜 to prepare a positive electrode.

A lithium metal battery (pouch cell) was produced through a polyethylene separator (porosity: about 48%) between the positive electrode and the negative electrode (thickness: about 20 μm) obtained according to the above procedure. Here, a liquid electrolyte was added between the positive electrode and the lithium metal negative electrode. As the liquid electrolyte, 1,2-dimethoxyethane (DME) in a 2: 8: volume ratio and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (1,1 , And 2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE) dissolved in a mixed solvent of 1.0 M LiN (SO ₂ F) ₂ (hereinafter referred to as LiFSI) was used.

The lithium metal battery (pouch cell) manufactured according to the above process was not subjected to a pressing process using a glass plate and a clip on the outside of the cell.

Example  5: Manufacture of cathode and lithium metal battery

A negative electrode was prepared in the same manner as in Example 1 except that a poly (acrylonitrile-b-butadiene-b-styrene) block copolymer was further added during the preparation of the protective film forming composition.

The content of the poly (acrylonitrile-b-butadiene-b-styrene) block copolymer was 10 parts by weight based on 100 parts by weight of poly (styrene-co-divinylbenzene) copolymer microspheres. The weight average molecular weight of the poly (acrylonitrile-b-butadiene-b-styrene) block copolymer was about 100,000 Daltons, and the mixing weight ratio of the polyacrylonitrile block, polybutadiene block and polystyrene block was 0.25: 0.25: 0.5 .

A lithium metal battery was prepared in the same manner as in Example 4 using the negative electrode.

Example  6: Manufacture of cathode

The content of the poly (acrylonitrile-b-butadiene-b-styrene) block copolymer is Except that 1 part by weight of poly (styrene-b-divinylbenzene) copolymer was changed to 100 parts by weight based on 100 parts by weight of the poly (styrene-b-divinylbenzene) copolymer.

Example  7-8: Preparation of cathode

Except that the average particle size of the poly (styrene-b-divinylbenzene) block copolymer microspheres was changed to about 1.3 占 퐉 and 50 占 퐉, respectively, to prepare a negative electrode.

Example  9: Manufacture of lithium metal battery

A lithium metal battery was produced in the same manner as in Example 4, except that the lithium metal battery (pouch cell) manufactured in Example 4 was subjected to a pressing process using a glass plate and a clip outside the cell.

Example  10-16: Manufacture of Lithium Metal Battery

A lithium metal battery (pouch cell) manufactured in accordance with Example 4 was subjected to a pressing process using a glass plate and a clip on the outside of the cell using the negative electrode obtained in Examples 2 to 8 instead of the lithium negative electrode obtained in Example 1 The procedure of Example 4 was otherwise repeated to produce a lithium metal battery.

Example  17: Manufacture of cathode and lithium metal battery

A negative electrode was prepared in the same manner as in Example 1 except that the average particle diameter of the poly (styrene-b-divinylbenzene) block copolymer microspheres was changed to about 5 탆. The same procedure as in Example 9 To prepare a lithium metal battery.

Example  18: Manufacture of lithium metal battery

LiCoO _{2 was used} instead of LiNi _{0 . 6} Co _{0 . 2} Al _{0 . 2} O ₂ was used in place of lithium aluminum hydride to prepare a lithium metal battery.

Example  19: Manufacture of lithium metal battery

LiCoO _{2 was used} instead of LiNi _{0 . 6} Co _{0 . 2} Al _{0 . 2} O ₂ was used in place of lithium aluminum hydride to prepare a lithium metal battery.

Example  20: Manufacture of cathode and lithium metal battery

(Styrene-b-divinylbenzene) copolymer microspheres (average particle size: about 3 탆) represented by the general formula (1) (large particle diameter: about 3 탆) in preparing a mixture containing 5% by weight of a block copolymer for producing a protective film- Except that poly (styrene-b-divinylbenzene) copolymer microspheres (average particle diameter = about 1.3 占 퐉) (small particle size particles) represented by the formula (1) (EPR-PSD-3, manufactured by EPRUI) , The same procedure as in Example 1 was carried out to prepare a negative electrode. The weight ratio of the large diameter particles to the small particle diameter particles in the protective film forming composition was 8: 2. The protective film contained a crosslinked product of diethylene glycol diacrylate (DEGDA) disposed in the space between the microspheres and the microspheres. Here, the content of the crosslinked product of diethylene glycol diacrylate (DEGDA) was 20 parts by weight based on 100 parts by weight of the poly (styrene-b-divinylbenzene) block copolymer microspheres.

Example 6 time of manufacturing the negative electrode instead of using the negative electrode prepared according to the process, a composition for forming a positive electrode active material LiCoO ₂ instead of LiNi _{0. 6} Co _{0 . 2} Al _{0 . 2} O ₂ was used in place of lithium aluminum hydride to prepare a lithium metal battery.

Example  21: Manufacture of Lithium Metal Battery

The procedure of Example 20 was repeated to produce a negative electrode having a protective film formed on a lithium metal. The protective film contained a crosslinked product of diethylene glycol diacrylate (DEGDA) disposed in the space between the microspheres and the microspheres.

Separately, LiNi _{0 . 6} Co _{0 . 2} Al _{0 . 2} O ₂ , Super-P (Timcal Ltd.), polyvinylidene fluoride (PVdF) and N-methyl pyrrolidone were mixed to obtain a composition for forming a positive electrode active material layer. The mixing weight ratio of LiNi _0.6 Co _0.2 Al _0.2 O ₂ , the conductive agent, and PVDF in the composition for forming the positive electrode active material layer was 97: 1.5: 1.5.

The composition for forming the cathode active material layer was coated on an aluminum foil (thickness: about 15 탆), dried at 25 캜, and dried. The dried product was vacuum dried at about 110 캜 to prepare a positive electrode.

A lithium metal battery (pouch cell) was produced through a polyethylene separator (porosity: about 48%) between the positive electrode and the negative electrode (thickness: about 20 μm) obtained according to the above procedure. Here, a liquid electrolyte was added between the positive electrode and the lithium metal negative electrode. As the liquid electrolyte, 1,2-dimethoxyethane (DME) in a 2: 8: volume ratio and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (1,1 , And 2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE) dissolved in a mixed solvent of 1.0 M LiN (SO ₂ F) ₂ (hereinafter referred to as LiFSI) was used.

Example  22: Manufacture of cathode and lithium metal battery

Except that a poly (styrene-b-isoprene-b-styrene) block copolymer was used in place of the poly (acrylonitrile-b-butadiene-b-styrene) block copolymer of Formula 2 Thereby preparing a negative electrode. In the poly (styrene-b-isoprene-b-styrene) block copolymer, the blend weight ratio of polystyrene block, polyisoprene and polystyrene block was 22:56:22.

A lithium metal battery was produced in the same manner as in Example 19 using the negative electrode.

Example  23: Manufacture of cathode and lithium metal battery

(Styrene-b-divinylbenzene) copolymer microsphere having an average particle diameter of about 3 占 퐉 and a poly (styrene-b-divinylbenzene) copolymer microsphere having an average particle diameter of about 3 占 퐉 and an average particle diameter of about 8 (Styrene-b-divinylbenzene) copolymer microspheres at a weight ratio of 1: 1 was prepared in the same manner as in Example 9 to prepare a negative electrode.

Example  24: Manufacture of cathode and lithium metal battery

(Styrene-b-divinylbenzene) block copolymer instead of the poly (styrene-b-divinylbenzene) block copolymer in the weight ratio of 9: A negative electrode was prepared, and a lithium metal battery was produced in the same manner as in Example 9.

Example  25: Manufacture of cathode

Except that the average particle size of the poly (styrene-b-divinylbenzene) block copolymer microspheres was changed to about 8 mu m, respectively, to prepare a negative electrode. The same procedure as in Example 9 was carried out A lithium metal battery was prepared.

Example  26-27: Preparation of protective film

Instead of the poly (styrene-b-divinylbenzene) block copolymer microsphere having a weight ratio of styrene block and divinylbenzene block of 9: 1 was 98: 2 (49: 1) instead of styrene block and divinylbenzene block. Or 95: 5 was used instead of the poly (styrene-b-divinylbenzene) copolymer microspheres prepared in Example 1. The procedure of Example 1 was repeated to prepare a negative electrode, and lithium A metal battery was produced.

Example  28: Manufacture of cathode and lithium metal battery

A negative electrode was prepared in the same manner as in Example 1 except that the average particle diameter of the poly (styrene-b-divinylbenzene) block copolymer microspheres was changed to 9 탆, and the same procedure as in Example 9 was carried out Thereby preparing a lithium metal battery.

Comparative Example  1: Manufacture of cathode and lithium metal battery

LiCoO ₂ , Super-P (Timcal Ltd.), polyvinylidene fluoride (PVdF) and N-methyl pyrrolidone were mixed to obtain a positive electrode composition. The mixing ratio by weight of LiCoO ₂ , the conductive agent and PVDF in the positive electrode composition was 97: 1.5: 1.5.

The above cathode composition was coated on an aluminum foil (thickness: about 15 탆), dried at 25 캜, and dried, and dried at about 110 캜 under vacuum to prepare a cathode.

A lithium metal battery (coin cell) was produced through a polyethylene separator (porosity: about 48%) between the positive electrode obtained by the above procedure and a lithium metal negative electrode (thickness: about 20 μm). Here, a liquid electrolyte was added between the positive electrode and the lithium metal negative electrode. As the liquid electrolyte, 1,2-dimethoxyethane (DME) in a 2: 8: volume ratio and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (1,1 , And 2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE) dissolved in a mixed solvent of 1.0 M LiN (SO ₂ F) ₂ (hereinafter referred to as LiFSI) was used.

Comparative Example  2: Manufacture of cathode and lithium metal battery

Polystyrene (weight average molecular weight = 100,000) was added to anhydrous tetrahydrofuran to obtain a 5 wt% polystyrene-containing mixture. The weight average molecular weight of polystyrene was about 100,000 Daltons.

Lithium bis (fluorosulfonyl) imide (LiFSI) {LiN (SO ₂ F) ₂ } was added to the polystyrene-containing mixture to obtain a composition for forming a protective film. Here, the content of LiFSI was about 30 parts by weight based on 100 parts by weight of the polystyrene.

The composition for forming a protective film was coated on the top of a lithium metal thin film (thickness: about 20 mu m) with a doctor blade to a thickness of about 3 mu m.

The coated product was dried at about 25 캜 and then dried under vacuum at about 40 캜 for about 24 hours to prepare a negative electrode having a protective film on lithium metal.

Using the negative electrode, the same procedure as in Comparative Example 1 was carried out to prepare a lithium metal battery.

Comparative Example  3-4: Preparation of cathode and lithium metal battery

(Styrene-b-divinylbenzene) block copolymer microspheres having a mean particle size of 1 mu m and 0.2 mu m, respectively, were prepared in the same manner as in Example 1 to prepare a negative electrode . The negative electrode was used in the same manner as in Comparative Example 1 to prepare a lithium metal battery.

Comparative Example  5: Manufacture of lithium metal battery

Instead of LiCoO ₂ , LiNi _{0 . 6} Co _{0 . 2} Al _{0 . 2} O ₂ was used in place of the lithium metal battery of Comparative Example 1 to produce a lithium metal battery.

Comparative Example  6-7: Preparation of cathode and lithium metal battery

(Al ₂ O ₃ ) was used instead of the poly (styrene-b-divinylbenzene) block copolymer microsphere in the preparation of the protective film forming composition and the average particle size of alumina was 10 nm (0.01 탆) and 50 nm (0.05 탆) The procedure of Example 1 was otherwise repeated to produce a negative electrode. The negative electrode was used in the same manner as in Comparative Example 1 to prepare a lithium metal battery.

Evaluation example  1: Scanning electron microscope analysis

1) Example 1

The surface and cross-sectional states of the negative electrode prepared according to Example 1 were analyzed using a scanning electron microscope (SEM). The scanning electron microscope (SEM) was a SU-8030 manufactured by Hitachi.

SEM cross-sectional photographs of the lithium negative electrode prepared according to Example 1 are shown in FIGS. 2A and 2B.

Referring to this, it can be seen that the protective film in the negative electrode manufactured according to Example 1 has microspheres arranged in a single layer structure on the surface of the lithium metal thin film and does not cause aggregation between the microspheres.

Also, scanning electron microscopy / energy dispersive spectroscopy (SEM / EDS) analysis was performed on the negative electrode prepared in Example 1.

The results of the analysis are shown in FIG. 3D and FIG. 3E.

Referring to this, it was confirmed that the protective film contained an oxygen component derived from a crosslinked product of diethylene glycol diacrylate (DEGDA).

2) Example 5

The state of the cathode surface prepared according to Example 5 was analyzed by using an electron scanning microscope, and the results are shown in Figs. 3A to 3C. 3A shows a monodisperse single layer, and the anode protective layer shown in Figs. 3B and 3C has a bilayer structure.

As shown in FIGS. 3A to 3C, it was found that the protective film in the lithium negative electrode manufactured according to Example 5 had microspheres arranged in a monolayer structure on the surface of lithium metal, and no aggregation occurred between the microspheres. It was also found that the protective film formed on the surface of the lithium metal had a monospaced microsphere and a closed packed arrangement.

3) Example 23

The state of the lithium negative electrode surface prepared according to Example 23 was analyzed using a scanning electron microscope (SEM). The SEM analysis photograph is shown in Fig. 3H.

Referring to this, it can be seen that the lithium negative electrode of Example 23 has uniformly well dispersed microspheres of two sizes on the lithium metal.

Evaluation example  2: Lithium electrodeposition density  And Electronic scanning microscope  analysis

) Examples 10, 19 and 20 and Comparative Examples 1 and 2

When the lithium metal battery prepared according to Examples 10, 19 and 20 and Comparative Examples 1 and 2 reached a voltage of 4.40 V (vs. Li) at a current of 0.1 C rate (0.38 mA / cm ² ) at 25 ° C. , And then cut off at a current of 0.05 C rate while maintaining 4.40 V in the constant voltage mode. After one charge, the change in thickness of the pouch exterior was measured using a lithium micrometer in a lithium metal battery, and the results are shown in Table 1 below. The thickness, thickness variation, and lithium electrodeposition density of the lithium electrodeposited layer formed on the cathode were measured, and the results of the electrodeposition density evaluation are shown in Table 2 below.

division Thickness Change (㎛) Example 10 27 Example 19 23 Example 20 22 Comparative Example 1 68

division Lithium electrodeposition density (g / cc) Thickness (탆) of the lithium electrodeposited layer The thickness variation (占 퐉) of the lithium electrodeposition layer Example 10 0.334 27 ± 3 Example 19 0.325 23 ± 3 Example 20 0.343 22 ± 3 Comparative Example 1 0.113 68 ± 10 Comparative Example 2 0.262 29 ± 5

With reference to Tables 1 and 2, the lithium metal batteries of Examples 10, 19, and 20 had a reduced thickness variation as compared with the case of Comparative Example 1.

Referring to Table 2, the lithium metal batteries prepared according to Examples 10, 19, and 20 had an increased electrodeposited density as compared with Comparative Examples 1 and 2.

2) Example 13 and Comparative Example 1

The surface and the cross-sectional state of the negative electrode having the lithium electrodeposited layer formed in the lithium metal battery according to Example 13 and Comparative Example 1 were analyzed by an electron scanning microscope. FIG. 4A schematically shows a cross-sectional structure of a cathode having a lithium electrodeposited layer formed in the lithium metal battery according to Example 13. FIG. 5A schematically shows a sectional structure of a negative electrode in the lithium metal battery according to Comparative Example 1. FIG.

Referring to FIG. 5A, in the lithium metal battery of Comparative Example 1, a lithium metal 51 is stacked on the anode current collector 50, and a lithium dendrite 52 is formed thereon. On the other hand, in the lithium metal battery of Example 13, a lithium metal 41 is stacked on an anode current collector 40 such as a copper thin film as shown in FIG. 4A, and particles 43 and spaces A protective film 42 containing a crosslinked product 45 of a polymerizable oligomer present in the polymerizable oligomer is disposed. A lithium electrodeposited layer 46 is formed between the lithium metal 41 and the protective film 42.

The SEM state of the cathode in the lithium metal battery manufactured according to Example 13 is as shown in Figs. 4B and 4C. The surface state of the negative electrode in the lithium metal battery manufactured according to Comparative Example 1 is as shown in FIG. 5B and FIG. 5C.

With reference to this, in the case of Comparative Example 1, lithium dendrite was largely grown, whereas in the lithium metal battery according to Example 13, lithium dendrite was hardly observed.

As shown in FIGS. 4D and 5D, unlike the negative electrode of Comparative Example 1, the negative electrode of Example 13 has a structure in which a very dense lithium electrodeposited layer is formed on the upper portion of the lithium metal thin film.

3) Example 9, Example 15, Example 17, Example 28, Comparative Example 6 and Comparative Example 7

The lithium metal battery prepared in Example 9, Example 15, Example 17, Example 28, Comparative Example 6, and Comparative Example 7 was subjected to a voltage of 0.1 C rate (0.38 mA / cm ² ) at 25 ° C After constant current charging until reaching 4.40 V (vs. Li), it was then cut off at a current of 0.05 C rate while maintaining 4.40 V in constant voltage mode. After one-time charging, the change in the thickness of the pouch exterior was measured using a lithium micrometer in a lithium metal battery, and it is shown in Table 3 below. The thickness, thickness variation and lithium electrodeposition density of the lithium electrodeposited layer formed on the cathode were measured, and the results of the electrodeposition density evaluation are shown in Table 3 below. Here, the lithium electrodeposition density is calculated from the change in the thickness of the pouch exterior, and the thickness of the lithium electrodeposited layer is a result obtained by observing the lithium electrodeposited layer after cell decomposition with an SEM.

division Lithium electrodeposition density
(g / cc) (g / cm 3) Exterior pouch thickness
change
(탆) The lithium electrodeposition layer
thickness
(탆) The lithium electrodeposition layer
Thickness deviation (탆) Example 9 / P (S-DVB) 3 m 0.343 21-23 19-21 ± 2 Example 15 / P (S-DVB) 1.3 占 퐉 0.32-0.33 22-24 20-22 ± 2 Example 17 / P (S-DVB) 5 占 퐉 0.32-0.33 22-24 20-22 ± 2 Example 28 / P (S-DVB) 9 m 0.31-0.32 23-26 21-24 ± 3 Comparative Example 6 / Al ₂ O ₃ 10 nm (0.01 탆) 0.255-0.265 29-32 27-30 ± 3 Comparative Example 7 / Al ₂ O ₃ 50 nm (0.05 탆) 0.25 29-33 28-31 ± 3

With reference to Table 3, the lithium metal batteries of Examples 9, 15, 17, and 28 were compared with those of Comparative Examples 6 and 7

The thickness of the outer pouch, the variation of the thickness and the thickness of the lithium electrode layer were decreased, and the lithium electrodeposition density was increased.

4) Examples 18 and 20, Comparative Examples 6 and 7

The lithium metal cells prepared in accordance with Examples 18 and 20 and Comparative Examples 6 and 7 were subjected to a constant current of 0.40 mA / cm ² at a current of 0.1 C rate (0.38 mA / cm ² ) at 25 캜 until the voltage reached 4.40 V After charging, it was then cut off at a current of 0.05 C while maintaining 4.40 V in constant voltage mode. After one-time charging, the change in the thickness of the pouch exterior was measured using a lithium micrometer in a lithium metal battery, and it is shown in Table 4 below. The lithium electrodeposited density was calculated from the change in the thickness of the external pouch, and the thickness of the lithium electrodeposited layer was obtained by observing the lithium electrodeposited layer after cell decomposition with an SEM.

The results of measurement of the thickness of the lithium electrodeposited layer formed on the negative electrode, the thickness deviation of the lithium electrodeposited layer, and the lithium electrodeposited density are shown in Table 4 below.

division Lithium electrodeposition density
(g / cc) (g / cm3) Exterior pouch thickness
change
(탆) The lithium electrodeposition layer
Thickness (㎛) The thickness variation (占 퐉) of the lithium electrodeposition layer Example 18 / P (S-DVB) 3 m 0.343 21-23 19-21 ± 2 Example 20 / P (S-DVB)
(3 mu m + 1.3 mu m) 0.356 20-22 18-20 ± 2 Comparative Example 6 / Al ₂ O ₃ 10 nm (0.01 탆) 0.255-0.265 29-32 27-30 ± 3 Comparative Example 7 / Al ₂ O ₃ 50 nm (0.05 탆) 0.25 29-33 28-31 ± 3

Referring to Table 4, the lithium metal batteries of Examples 18 and 20 showed a decrease in the thickness of the outer pouch, a variation in thickness and thickness of the lithium electrodeposition layer, and an increase in the lithium electrodeposition density, as compared with Comparative Examples 6 and 7 Could know.

Evaluation example  3: Lithium electrodeposition density

The lithium metal battery produced according to Example 10 and Comparative Example 1 was subjected to constant current charging at a current of 0.1 C rate (0.38 mA / cm ² ) at 25 ° C until the voltage reached 4.40 V (vs. Li) Followed by cut-off at a current of 0.05 C rate while maintaining 4.40 V in the constant voltage mode. After one charge, the thickness variation of the pouch exterior thickness and the thickness of the lithium electrodeposition layer were measured by using a lithium micrometer in the lithium metal battery, and the results are shown in Tables 1 and 2. Also, the distribution of the thickness variation of the lithium electrodeposited layer formed on the lithium metal cathode was examined. The thickness variation distribution results of the lithium metal battery produced according to Example 10 and Comparative Example 1 are shown in FIGS. 3F and 3G, respectively. Referring to the results, it can be seen that the lithium metal battery manufactured according to Example 10 has a uniform thickness of the electrodeposited layer compared with the case of Comparative Example 1.

Evaluation example  4: Charging and discharging  Cell thickness variation with cycle monitoring

The lithium metal battery prepared in Example 20 and Comparative Example 1 was subjected to constant current charging until the voltage reached 4.40 V (vs. Li) at a current of 0.1 C rate at 25 ° C, followed by 4.40 V in the constant voltage mode And cut off at a current of 0.05 C rate. Then, the discharge was performed at a constant current of 0.1 C rate until the voltage reached 2.8 V (vs. Li) during the discharge (Mars phase, 1 ^st cycle). The charging and discharging process was performed two more times to complete the conversion process.

The lithium secondary battery having undergone the above conversion step was charged at a constant current of 0.7 C at room temperature (25 ° C) until the voltage reached 4.4 V versus the lithium metal, and then cut to a cut-off voltage of 4.4 V Lt; RTI ID = 0.0 &gt; of &lt; / RTI &gt;

The charging / discharging process was repeated 35 times repeatedly.

The cell thickness variation was monitored as the charge and discharge cycles were repeated. As a result of the monitoring, it was found that the lithium metal battery produced according to Example 20 had a reduced cell thickness change as compared with the case of Comparative Example 1.

Evaluation example  5: Impedance measurement

1) Examples 18 and 20 and Comparative Example 1

The resistance of the lithium metal battery manufactured according to Examples 18 and 20 and Comparative Example 1 was measured at 25 ° C. by the 2-probe method using an impedance analyzer (Solartron 1260A Impedance / Gain-Phase Analyzer). The amplitude was ± 10 mV, and the frequency range was 0.1 Hz to 1 MHz.

A Nyguist plot of the impedance measurement results when the elapsed time after manufacture of the lithium secondary battery according to Examples 18 and 20 and Comparative Example 1 was 24 hours is shown in FIG. In FIG. 6, the interface resistance between the electrode and the protective film is determined by the position and size of the semicircle. In the lithium metal batteries produced according to Examples 18 and 20 and Comparative Example 1, the bulk resistance was examined and shown in Table 5 below.

In the lithium secondary battery of Example 18, MS having an average particle diameter of 3 占 퐉 was used in the production of the cathode protecting film, MS in the lithium secondary battery of Example 20 having an average particle diameter of about 3 占 퐉 and an average particle diameter of about 1.3 占Lt; / RTI &gt;

division Bulk Resistance (Ω) Example 18 0.53 Example 20 0.6 Comparative Example 1 0.44

6 and Table 5, it was found that the lithium metal batteries of Examples 18 and 20 had excellent interfacial resistance characteristics.

2) Example 9 and Comparative Example 1

In Example 9 and Comparative Example 1, a lithium metal battery was charged at a constant current of 0.1 C rate at 25 DEG C until the voltage reached 4.40 V (vs. Li), and then maintained at 4. 0 V in constant voltage mode, rate cut-off. &lt; / RTI &gt; Then, the discharge was performed at a constant current of 0.1 C rate until the voltage reached 2.8 V (vs. Li) during the discharge (Mars phase, 1 ^st cycle). The charging and discharging process was performed two more times to complete the conversion process.

The lithium metal battery having undergone the above conversion step was charged at a constant current of 0.7 C at room temperature (25 캜) until the voltage reached a voltage range of 4.4 V versus lithium metal. Then, a cut-off voltage Lt; 0 &gt; C).

The charging / discharging process was repeatedly performed 100 times repeatedly. The change in resistance characteristics before and after elapse of 100 cycles is shown in Fig.

Referring to FIG. 12, it can be seen that the increase in cell resistance of the lithium metal battery of Example 9 is reduced after 100 cycles have elapsed as compared with the case of Comparative Example 1.

Evaluation example  6: Charging and discharging  Characteristics (discharge capacity)

1) Example 22 and Comparative Example 5

The lithium metal battery prepared in accordance with Example 22 and Comparative Example 5 was subjected to constant current charging at a current of 0.1 C rate at 25 DEG C until the voltage reached 4.40 V (vs. Li), followed by 4.40 V in the constant voltage mode And cut off at a current of 0.05 C rate. Then, the discharge was performed at a constant current of 0.1 C rate until the voltage reached 2.8 V (vs. Li) during the discharge (Mars phase, 1 ^st cycle). The charging and discharging process was performed two more times to complete the conversion process.

The lithium metal battery having undergone the above conversion step was charged at a constant current of 0.7 C at room temperature (25 캜) until the voltage reached 4.4 V versus lithium metal, and then cut to a cut-off voltage of 3.0 V Lt; 0 &gt; C).

The charging / discharging process was repeated 200 times repeatedly. The change in discharge capacity according to the charge-discharge cycle is shown in Fig.

Referring to FIG. 7, it can be seen that the lithium metal battery manufactured according to Example 22 had improved life characteristics as compared with Comparative Example 5.

2) Example 9 and Comparative Example 1

The lithium metal battery prepared in Example 9 and Comparative Example 1 was subjected to constant current charging at a current of 0.1 C rate at 25 DEG C until the voltage reached 4.40 V (vs. Li), followed by 4.40 V in the constant voltage mode And cut off at a current of 0.05 C rate. Then, the discharge was performed at a constant current of 0.1 C rate until the voltage reached 2.8 V (vs. Li) during the discharge (Mars phase, 1 ^st cycle). The charging and discharging process was performed two more times to complete the conversion process.

The lithium metal battery having undergone the above conversion step was charged at a constant current of 0.7 C at room temperature (25 캜) until the voltage reached 4.4 V versus lithium metal, and then cut to a cut-off voltage of 3.0 V Lt; 0 &gt; C).

The charging / discharging process was repeatedly performed for a total of 190 times. The change in discharge capacity according to the charge-discharge cycle is shown in Fig.

Referring to Fig. 11, the lithium metal battery of Example 9 exhibited a capacity retention rate of about 90% in a cycle of 190 times. On the other hand, the lithium metal battery of Comparative Example 1 exhibited a capacity retention rate of 90% at 146 cycles. From these results, it was found that the capacity maintenance ratio of the lithium metal battery of Example 9 was improved by about 30% as compared with that of Comparative Example 1.

Evaluation example  7: Rate  characteristic

The rate-limiting characteristics of the lithium metal battery produced according to Example 13 and Comparative Example 1 were examined. The results of the rate-limiting characteristic evaluation are shown in Fig.

The lithium metal batteries prepared in Example 13 and Comparative Example 1 were subjected to constant current charging at a current of 0.1 C rate at 25 DEG C until the voltage reached 4.4 V (vs. Li), and then 4.4 V was maintained in the constant voltage mode And cut off at a current of 0.05 C rate. Then, at the time of discharging, the battery was discharged at a constant current of 0.1 C rate until the voltage reached 3.0 V (vs. Li). The charging and discharging process was performed two more times to complete the conversion process.

Subsequently, the batteries were charged under the conditions of constant current (A1) and constant voltage (4.4 V, 0.05 C cut-off) according to the conditions 1 to 5 of Table 6, respectively, and then rested for 10 minutes. Then, discharge was performed under the condition of the constant current (A2) according to the conditions 1 to 5 in Table 6 until the voltage reached 3.0 V. The rate capability of the lithium metal battery was evaluated by charging / discharging at 5 different current conditions. The rate-limiting performance of each lithium battery was evaluated under the additional conditions shown in Fig. 8, in addition to the conditions shown in Table 6 below.

Condition 1 Condition 2 Condition 3 Condition 4 Condition 5 Current A1 (C) 0.2 0.7 0.7 0.7 0.7 Current A2 (C) 0.2 0.5 1.0 1.5 2.0

8 shows the rate-limiting performance of the lithium metal battery manufactured according to Example 13 and Comparative Example 1. Referring to FIG. 8, the lithium metal battery manufactured according to Example 13 has a lithium metal And it is found that the rate-limiting performance is improved by bracing the battery.

On the other hand, with respect to the lithium metal battery produced according to Examples 23 to 27,

The rate-limiting performance was evaluated in the same manner as in the case of the lithium metal battery of Example 13.

As a result of the evaluation, the lithium metal battery produced according to Examples 23 to 27 exhibited a rate-limiting performance equivalent to that of Example 13.

Evaluation example  8: Tensile modulus

Tetrahydrofuran (THF) was dissolved in an argon glove box for 24 hours at a temperature of about 25 DEG C in the result of casting and casting the composition for forming a protective film according to Examples 1-4 and Comparative Example 2-4 on a substrate Evaporated slowly and dried at 25 &lt; 0 &gt; C for 24 hours under vacuum to form a protective film in film form. At this time, the thickness of the protective film was about 50 탆.

The tensile modulus of the protective film was measured using DMA800 (TA Instruments), and the protective film specimen was prepared through ASTM standard D412 (Type V specimens). The tensile modulus is also called Young's modulus.

The protective film was measured for strain at 25 ° C and at a relative humidity of about 30% at a rate of 5 mm per minute. The tensile modulus was obtained from the slope of the stress-strain curve.

As a result of the measurement of the tensile modulus of elasticity, it was found that the tensile modulus of the protective film prepared according to Examples 1 to 4 was 10 ⁶ Pa or more, as compared with the case of Comparative Example 3-5. Using the protective film prepared according to Example 1 having such characteristics, the volume change of the lithium metal anode and the growth of lithium dendrite can be effectively suppressed.

Evaluation example  9: ion conductivity

The ionic conductivity of the protective film prepared according to Examples 1 and 5 was measured according to the following method.

The protective film was subjected to a voltage bias of 10 mV in the frequency range of 1 Hz to 1 MHz and the temperature was scanned and the ion conductivity was evaluated by measuring the resistance.

As a result of the evaluation, the protective films prepared according to Examples 1 and 5 exhibited excellent ion conductivity.

Evaluation example  10: Cell thickness change

The lithium metal battery prepared in Example 22 and Comparative Example 1 was subjected to constant current charging at a current of 0.1 C rate at 25 DEG C until the voltage reached 4.4 V (vs. Li), and then 4.4 V was maintained in the constant voltage mode And cut off at a current of 0.05 C rate. Then, at the time of discharging, the battery was discharged at a constant current of 0.1 C rate until the voltage reached 3.0 V (vs. Li). The charging and discharging process was performed two more times to complete the conversion process.

next, The battery was charged at a constant current of 0.7 C rate at 25 캜, charged at a constant voltage (4.4 V, 0.05 C cut-off), and then rested for 10 minutes. Subsequently, the battery was discharged at a current of 0.5 C at a constant current (under the condition of 3.0 V). This charging and discharging process was repeatedly performed for a total of 200 times.

The change in cell thickness at each cycle repeat was investigated and is shown in FIG.

Referring to FIG. 10, it was found that the lithium metal battery of Example 22 had a decrease in cell thickness change as compared with that of the lithium metal battery of Comparative Example 1.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the exemplary embodiments or constructions. It will be apparent to those skilled in the art that various modifications and variations are possible in light of the above teachings will be. Accordingly, the scope of protection of the present invention should be determined by the appended claims.

10: collector 11: lithium metal electrode
12: protective film 13: particles
14: ion conductive polymer 15: crosslinked polymeric oligomer
16: lithium electrodeposition layer 17: SEI
21: anode 22: cathode
23: protective film 24: electrolyte
30: lithium metal battery 34: case

Claims (32)

A lithium metal electrode comprising a lithium metal or a lithium metal alloy; And
And a protective film disposed on at least a portion of the lithium metal electrode,
Young's modulus of the protective film is 10 ⁶ Pa or more,
Wherein the protective film comprises at least one particle selected from organic particles, inorganic particles and organic particles having a size of more than 1 탆 and not more than 100 탆,
Wherein the protective film comprises a crosslinked material of a polymerizable oligomer present between the particles. The method according to claim 1,
Wherein the polymerizable oligomer has a weight average molecular weight of 5,000 or less. The method according to claim 1,
The polymerizable oligomer may be selected from the group consisting of diethylene glycol diacrylate (DEGDA), triethylene glycol diacrylate (TEGDA), tetraethylene glycol diacrylate (TTEGDA), polyethylene glycol diacrylate (PEGDA), dipropylene glycol diacrylate (DPGDA), tripropylene glycol diacrylate (TPGDA), ethoxylated trimethylolpropane triacrylate (ETPTA), acrylate-functionalized ethylene oxide, ethoxylated Propoxylated neopentyl glycol diacrylate (NPPOGDA), trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate (TMPTA), trimethylolpropane trimethacrylate (TMPTMA), pentaerythritol triacrylate (PETA), ethoxylated propoxylated trimethylolpropane triacrylate (TMPEOTA) / (TMPPOTA), propoxylated glyceryl triacrylate, tris (2-hydroxyethyl) isocyanurate tri Wherein the negative electrode is at least one selected from the group consisting of acrylate (THEICTA), pentaerythritol tetraacrylate (PETTA) and dipentaerythritol pentaacrylate (DPEPA). The method according to claim 1,
Wherein the amount of the cross-linked product of the polymerizable oligomer is 10 to 50 parts by weight based on 100 parts by weight of the particles. The method according to claim 1,
Wherein the particles of the protective film are chemically or physically crosslinked. The method according to claim 1,
Wherein the particles are microspheres having an average particle diameter of 1.1 to 50 占 퐉. The method according to claim 1,
Wherein the particles of the protective film comprise at least one polymer selected from the group consisting of polystyrene, a copolymer containing a styrene repeating unit, a copolymer containing a repeating unit having a crosslinkable functional group, and a crosslinked polymer. 8. The method of claim 7,
The polymer may be selected from the group consisting of polystyrene, a poly (styrene-divinylbenzene) copolymer, a poly (methyl methacrylate-divinylbenzene) copolymer, a poly (ethyl methacrylate-divinylbenzene) (Methacrylate-divinylbenzene) copolymer, poly (butyl methacrylate-divinylbenzene) copolymer, poly (propyl methacrylate-divinylbenzene) (Acrylonitrile-butadiene-styrene) copolymer, poly (styrene-acrylonitrile) copolymer, poly (styrene-acrylonitrile) (C1-C9 alkyl) methacrylate-butadiene-styrene) copolymer, poly (methyl methacrylate-acrylonitrile-butadiene-styrene) copolymer, - (C1-C9alkyl) At least one polymer selected from poly (acrylonitrile-styrene- (C1-C9 alkyl) acrylate) copolymers, and crosslinked polymers. The method according to claim 1,
The inorganic particles and the organic particles of the protective film may be selected from the group consisting of i) silsesquioxane having a cage structure, metal-organic framework (MOF), Li _{1 + x + y} Al _x Ti _{2 - x} Si _y P _{3 - y} O ₁₂ (0 <x <2, 0? Y <3), BaTiO ₃ , Pb (Zr _p Ti _1-p ) O ₃ (0 _{? P? 1} ) (PZT), Pb _{1 - x} La _x Zr _{1 - y} Ti _{y O 3 (PLZT) (O≤x} <1, O≤y <1), Pb (Mg 3 Nb 2/3) O 3 -PbTiO 3 (PMN-PT), HfO 2, SrTiO 3, SnO 2, CeO _{2, Na 2 O, MgO,} NiO, CaO, BaO, ZnO, ZrO 2, y 2 O 3, Al 2 O 3, TiO 2, SiO 2, SiC, Li 3 PO 4, Li x Ti y (PO 4) _{3 (0 <x <2,0 <} y <3), Li x Al y Ti z (PO 4) 3 (0 <x <2, 0 <y <1, 0 <z <3), Li 1 + x _{+ y (Al p Ga 1 -p} ) x (Ti q Ge 1-q) 2-x Si y P 3-y O 12 (O≤x≤1, O≤y≤1), Li x La y TiO 3 1, 0 <w <5), Li _x N _y (0 <x <2, 0 <y <3), LixGeyPzSw 4, 0 <y <2) , Li x Si y S z (0≤x <3,0 <y <2, 0 <z <4), Li x P y S z (0≤x <3, 0 < y <3, 0 <z < 7), Li 2 O, LiF, LiOH, Li 2 CO 3, LiAlO 2, Li 2 O-Al 2 O 3 -SiO 2 -P 2 O 5 -TiO 2 -GeO 2, At least one particle A selected from the group consisting of Li _{3 + x} La ₃ M ₂ O ₁₂ (M = Te, Nb, or Zr) (0? X? 5)
(ii) the cathode A has a crosslinkable functional group and has a structure crosslinked by these functional groups. The method according to claim 1,
Wherein the organic particles of the protective film are selected from the group consisting of a poly (styrene-divinylbenzene) copolymer, a poly (methyl methacrylate-divinylbenzene) copolymer, a poly (ethyl methacrylate-divinylbenzene) Poly (butyl methacrylate-divinylbenzene) copolymer, poly (butyl methacrylate-divinylbenzene) copolymer, poly (propyl methacrylate-divinylbenzene) Poly (styrene-acrylonitrile) copolymers, poly (styrene-methyl methacrylate) copolymers, poly (styrene-acrylonitrile) (Methacrylate-butadiene-styrene) copolymer, poly (styrene-acrylate) copolymer, poly (styrene-acrylonitrile) copolymer coalescence And a poly (acrylonitrile-styrene-acrylate) copolymer. The negative electrode for a lithium metal battery according to claim 1, wherein the block copolymer is a block copolymer. The method according to claim 1,
Wherein the protective film comprises a lithium salt or a liquid electrolyte. 12. The method of claim 11,
Wherein the liquid electrolyte occupies 30 to 60% by volume in the protective film. 12. The method of claim 11,
Wherein the liquid electrolyte comprises a lithium salt and an organic solvent. The method according to claim 1,
Wherein the protective film further comprises an ion conductive polymer. 14. The method of claim 13,
Wherein the ion conductive polymer is a homopolymer, a copolymer, or a crosslinked polymer. 15. The method of claim 14,
Wherein the negative electrode is a block copolymer containing the ion conductive polymeric polystyrene or the styrene repeating unit. The method according to claim 1,
The protective film may have a smaller size than one or more particles selected from among organic particles, inorganic particles, and organic particles having a size of more than 1 탆 and not more than 100 탆. Further comprising a second particle,
And the second particles have a size of 1 to 100 占 퐉. The method according to claim 1,
Wherein the protective film is a single layer or a multilayer including at least one particle selected from organic particles, inorganic particles and organic-inorganic particles having different sizes. The method according to claim 1,
The particles were prepared by mixing poly (styrene-co-divinylbenzene) copolymer microspheres having an average particle size of about 3 탆 and a poly (styrene-co-divinylbenzene) copolymer microparticle having an average particle diameter of about 8 탆 in a weight ratio of 1: Poly (styrene-co-divinylbenzene) copolymer microspheres having a mean particle size of about 3 占 퐉 or a 1: 1 weight ratio of poly (styrene-co-divinylbenzene) copolymer having an average particle diameter of about 1.1 占 퐉 or 1.3 占 퐉 Benzene) copolymer microspheres. The method according to claim 1,
The particles of the protective film include a crosslinked polymer,
Wherein the crosslinking polymer has a degree of crosslinking of 10 to 30%. The method according to claim 1,
And the porosity of the protective film is 5% or less. The method according to claim 1,
Wherein at least 80% of the pores of the protective film are filled with the crosslinked product of the polymerizable oligomer
Cathode for lithium metal batteries. The method according to claim 1,
Wherein the protective film further comprises at least one selected from the group consisting of an ionic liquid, a metal salt containing a Group 1 or Group 2 element and a nitrogen-containing additive, boron nitride, or a mixture thereof. 24. The method of claim 23,
Wherein the ionic liquid is selected from the group consisting of i) ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, At least one cation selected from triazolium-based compounds and mixtures thereof,
_{^{ii) BF 4 -, PF 6}} -, AsF 6 -, SbF 6 -, AlCl 4 -, HSO 4 -, ClO 4 -, CH 3 SO 3 -, CF 3 CO 2 -, Cl -, Br -, I - _{^{, SO 4 -, CF 3 SO}} 3 -, (FSO 2) 2 N -, (C 2 F 5 SO 2) 2 N - N, (C 2 F 5 SO 2) (CF 3 SO 2) -, and ( And at least one anion selected from at least one selected from the group consisting of CF ₃ SO ₂ ) ₂ N ^- . 24. The method of claim 23,
Wherein the metal salt containing the Group 1 element or the Group 2 element is at least one metal salt containing at least one selected from Cs, Rb, K, Ba, Sr, Ca, Na and Mg,
The nitrogen-containing additive may be selected from the group consisting of inorganic nitrate, organic nitrate, inorganic nitrite, organic nitrite, organic nitroso compound, organic nitroso compound, NO compound, Lithium (Li ₃ N). 14. The method of claim 13,
The lithium salt _{LiSCN, LiN (CN) 2,} LiClO 4, LiBF 4, LiAsF 6, LiPF 6, LiCF 3 SO 3, LiC (CF 3 SO 2) 3, LiN (SO 2 C 2 F 5) 2, LiN _{(SO 2 CF 3) 2,} LiN (SO 2 F) 2, LiSbF 6, LiPF 3 (CF 2 CF 3) 3, LiPF 3 (CF 3) 3 , and LiB (C ₂ O _{4) 2} is at least one lithium selected from the group consisting of Cathode for metal cells. 14. The method of claim 13,
Wherein the organic solvent is selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, fluoroethylene carbonate, gamma butyrolactone, dimethoxyethane, diethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl Ether, tetraethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, succinonitrile, sulfolane, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, adiponitrile, tetraethylene glycol dimethyl ether and 1,1,2,2- And tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether. A lithium metal battery comprising a positive electrode, a negative electrode of claim 1, and an electrolyte interposed therebetween. 29. The method of claim 28,
Wherein the electrolyte comprises at least one selected from a liquid electrolyte, a solid electrolyte, a gel electrolyte, and a polymer ionic liquid. 29. The method of claim 28,
Wherein the lithium metal battery comprises a separator. 29. The method of claim 28,
Wherein the lithium electrodeposited density in the lithium metal battery is 0.2 to 0.4 g / cm &lt; ³ &gt;. The method according to claim 1,
And the thickness of the protective film in the negative electrode is 0.1 to 4 占 퐉.

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