KR20210112924A - Composite electrolyte for lithium metal battery, preparing method thereof, and lithium metal battery comprising the same - Google Patents

Abstract

Provided are a composite electrolyte for a lithium metal battery including a lithium negative electrode, which inhibits growth of lithium dendrites, a manufacturing method thereof, and a lithium metal battery including the same. According to the present invention, the complex electrolyte comprises: a separator; a polymer electrolyte disposed on the separator and including a cross-linked polymer including a first monomer having at least two double bonds and a second monomer having one or more double bonds, lithium salt, and a nitrile-based compound; and a coating film disposed on the polymer electrolyte and including a cross-linked polymer of a first monomer having two or more double bonds and a second monomer having one or more double bonds. The first monomer contains at least three or more repeating units represented by chemical formula 1 and one selected from a group represented by chemical formula 2, which is bonded to both ends of the repeating unit.

Description

Composite electrolyte for lithium metal battery, manufacturing method thereof, and lithium metal battery comprising same

It relates to a composite electrolyte for a lithium metal battery, a manufacturing method thereof, and a lithium metal battery including the same.

A lithium secondary battery is a high-performance secondary battery having the highest energy density among currently commercialized secondary batteries, and may be used in various fields, such as, for example, an electric vehicle.

The polymer electrolyte of a lithium secondary battery contains a liquid electrolyte with high ion conductivity in a polymer matrix, has excellent lithium ion conductivity, and can realize electrochemical performance at room temperature despite being a semi-solid electrolyte.

However, when the polymer electrolyte reaches a region above the glass transition temperature (Tg) temperature of the polymer at a high temperature, it takes on the properties of an intermediate region between a solid and a liquid, or when a material such as a liquid electrolyte is collected inside, leakage of the liquid electrolyte may occur. can The leaked liquid electrolyte may cause a side reaction with the lithium metal anode.

Since the lithium metal anode has very high reactivity with the liquid electrolyte, in a lithium metal battery using a lithium metal anode, the interfacial resistance due to by-products on the surface of the lithium metal anode during the electrochemical reaction rapidly increases, causing vertical growth of dendrites and short circuit. This may cause a serious problem in terms of safety due to a decrease in battery life or an explosion due to a short circuit. Therefore, there is a need for a polymer electrolyte that has durability in a lithium metal battery using a lithium metal anode and does not have a risk of leakage of the liquid electrolyte contained therein even in a high-temperature environment.

One aspect is to provide a novel composite electrolyte for a lithium metal battery and a method for manufacturing the same.

Another aspect is to provide a lithium metal battery with improved performance, including the composite electrolyte described above.

According to one aspect, it is a composite electrolyte for a lithium metal battery including a lithium negative electrode,

The composite electrolyte comprises: a cross-linked polymer comprising i) a separator, ii) a first monomer having at least two double bonds and a second monomer having one or more double bonds on the separator; lithium salt; And a polymer electrolyte comprising a nitrile-based compound,

It is disposed on the polymer electrolyte and comprises a coating film containing a crosslinked polymer of a first monomer having two or more double bonds and a second monomer having one or more double bonds,

A composite electrolyte for a lithium metal battery is provided, wherein the first monomer contains at least three or more repeating units represented by Chemical Formula 1, and one selected from the group represented by Chemical Formula 2 is bonded to both ends of the repeating unit. .

[Formula 1]

,

,

In Formula 1, E is ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, diethylene glycol, alkanediol, ethoxylated alkanediol, propoxylated alkanediol , trimethylolpropane, ethoxylated trimethylolpropane, propoxylated trimethylolpropane, ditrimethylolpropane, ethoxylated ditrimethylolpropane, propoxylated ditrimethylolpropane, pentaerythritol, ethoxyl Lated pentaerythritol, propoxylated pentaerythritol, dipentaerythritol, ethoxylated dipentaerythritol, propoxylated dipentaerythritol, bisphenol A, ethoxylated bisphenol A, propoxylate It is a residue derived from the group selected from bisphenol A and combinations thereof,

n of each repeating unit is independently an integer from 1 to 20,

[Formula 2]

,

,

,

,

,

,

,

,

,

,

,

,

,

,

In Formula 2, R is independently a hydrogen atom, a C1-C10 alkyl group, a C6-C20 aryl group, or a combination thereof.

Anode according to another aspect; lithium negative electrode; and the above-mentioned composite electrolyte interposed therebetween; is provided.

According to another aspect, the separator includes a first monomer having at least two double bonds and a second monomer having one or more double bonds; lithium salt; and a first step of forming a polymer electrolyte on a separator by applying and curing a polymer electrolyte composition including a nitrile-based compound; and

On at least one surface of the polymer electrolyte, a coating film containing a crosslinked polymer of a first monomer having two or more double bonds and a second monomer having one or more double bonds is formed to form a coating film according to any one of claims 1 to 12. There is provided a method for manufacturing a composite electrolyte for a lithium metal battery comprising a second step of preparing the composite electrolyte.

The composite electrolyte for a lithium metal battery according to an exemplary embodiment has a low reactivity with lithium at high temperatures, so there is less concern about side reactions, and thus the growth of lithium dendrites can be suppressed. By using such a composite electrolyte, it is possible to manufacture a lithium metal battery that is safe and has a long lifespan.

1 schematically shows the structure of a composite electrolyte according to an embodiment.
2 and 3 are photographs showing the surface characteristics after disassembling the Li-Li symmetric cell of Preparation Example 1 and the Li-Li symmetric cell of Comparative Preparation Example 1, respectively.
4 is a graph showing the change in discharge voltage characteristics over time in the Li-Li symmetric cell employing the composite electrolyte of Examples 1 to 3;
5 shows the structure of a lithium metal battery according to an embodiment.

Hereinafter, an exemplary composite electrolyte for a lithium metal battery, a manufacturing method thereof, and a lithium metal battery including the same will be described in detail with reference to the accompanying drawings.

A composite electrolyte for a lithium metal battery including a lithium negative electrode is provided.

The composite electrolyte comprises: i) a separator; ii) a cross-linked polymer of a first monomer having at least two double bonds and a second monomer having one or more double bonds on the separator; lithium salt; and a polymer electrolyte comprising a nitrile compound, and a coating film disposed on the polymer electrolyte and containing a crosslinked polymer of a first monomer having two or more double bonds and a second monomer having one or more double bonds. .

The first monomer is a compound containing at least three or more repeating units represented by the formula (1), and one selected from the group represented by the following formula (2) is bonded to both ends of the repeating unit.

[Formula 1]

,

,

In Formula 1, E is ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, diethylene glycol, alkanediol, ethoxylated alkanediol, propoxylated alkanediol , trimethylolpropane, ethoxylated trimethylolpropane, propoxylated trimethylolpropane, ditrimethylolpropane, ethoxylated ditrimethylolpropane, propoxylated ditrimethylolpropane, pentaerythritol, ethoxyl Lated pentaerythritol, propoxylated pentaerythritol, dipentaerythritol, ethoxylated dipentaerythritol, propoxylated dipentaerythritol, bisphenol A, ethoxylated bisphenol A, propoxylate It is a residue derived from a group selected from tide bisphenol A and combinations thereof, and n of each repeating unit is independently an integer from 1 to 20;

[Formula 2]

,

,

,

,

,

,

,

,

,

,

,

,

,

,

In Formula 2, R is independently a hydrogen atom, a C1-C10 alkyl group, a C6-C20 aryl group, or a combination thereof.

Three or more repeating units represented by Formula 1 constituting the first monomer are selected to be the same as or different from each other. That is, the first monomer includes a repeating unit represented by Formula 1, but E of Formula 1 may be selected to be the same as or different from each other.

The crosslinked polymer has a network structure through chemical and/or physical bonding of the first monomer and the second monomer.

The first monomer has two or more double bonds at the terminal and is an oligomer having a weight average molecular weight of 500 or more, for example, 1,000 to 1,000,000, and has a structure including a structure of repetitive polyalkylene oxide, polyisocyanate, polyol, and the like. The weight average molecular weight of the oligomer is, for example, 10,000 to 50,000, 20,000 to 30,000, or 25,000.

The second monomer has one double bond and is an alkylene acrylate having 4 to 10 carbon groups and participates in random copolymerization and crosslinking together with the first monomer to form a structure of a polymer electrolyte.

The cross-linked polymer is present on the separator, and specifically may be present on the inside and the surface of the separator. The inside of the separator includes pores in the separator. The weight average molecular weight of the crosslinked polymer may be, for example, 10,000 to 600,000, 20,000 to 500,000, 30,000 to 400,000, 50,000 to 200,000, or 50,000 to 150,000.

Polymer electrolytes for general lithium metal batteries may cause leakage of liquid electrolytes, and the leaked liquid electrolytes have very high reactivity with lithium metal anodes, which may cause side reactions. As a result, the interfacial resistance due to by-products on the surface of the lithium metal negative electrode during the electrochemical reaction may rapidly increase or a short circuit may occur, thereby reducing the lifespan of the battery.

Accordingly, the inventors of the present invention have completed the present invention for a composite electrolyte that has no risk of leakage of the liquid electrolyte contained therein even in a high-temperature environment because durability is secured in a lithium metal battery using a lithium metal anode by solving the above problems.

1 schematically shows the structure of a composite electrolyte according to an embodiment.

Referring to FIG. 1 , the composite electrolyte has a structure containing a polymer electrolyte 11 and a coating film 12 and a coating film 13 disposed thereon. The polymer electrolyte 11 contains a separator, a crosslinked polymer, a lithium salt, and a nitrile-based compound. And the coating film 12 and the coating film 13 may have the same or different composition and/or thickness from each other.

The thickness of the polymer electrolyte 11 is 5 to 100 μm, 20 to 60 μm, or 25 to 45 μm. The total thickness of the coating film 12 and the coating film 13 is 5 to 100 μm, for example, 20 to 60 μm.

The polymer electrolyte constituting the composite electrolyte for a lithium metal battery according to an embodiment has a structure capable of collecting a liquid electrolyte with high ionic conductivity doped with a lithium salt and a random copolymer cross-linked structure in a separator. The liquid electrolyte is contained in the cross-linked structure to obtain the effect of blocking it from leaking out. Through this, it is possible to prevent leakage in a high-temperature environment, and by securing the durability of the polymer structure, there is no risk of leakage of the liquid electrolyte contained therein even in a high-temperature environment. In addition, it is possible to improve the stability of the electrochemical reaction with the effect of improving the side reaction with lithium metal.

Since the liquid electrolyte contains a nitrile-based compound and the polymer electrolyte has a plastic crystal electrolyte form, the polymer electrolyte and the composite electrolyte employing the same have excellent ion conductivity. As used herein, the term "plastic crystal electrolyte" has a property that the orientation or degree of freedom of chemical molecules constituting the electrolyte changes depending on the temperature range.

The nitrile-based compound may include succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, or a combination thereof.

As described above, the composite electrolyte contains a crosslinked polymer of the first and second monomers to supplement the fluidity of a general plastic crystal electrolyte. Heat stability is ensured because softening does not occur even when added.

In addition, the composite electrolyte according to an embodiment contains a polymer electrolyte without a change in structure when stored at a high temperature, and when this is used, the reactivity between the lithium metal and the composite electrolyte is suppressed. In addition, the composite electrolyte according to one embodiment is a lithium metal battery having low reactivity with lithium at high temperature, so there is little concern about side reactions, and safety is secured by inhibiting the growth of lithium dendrites, and a long lifespan is advantageous. These lithium metal batteries are used in mobile and automobile batteries to ensure stability, and high-capacity batteries can be implemented using lithium metal.

The second monomer cross-linked with the first monomer is a compound represented by the following formula (6), a compound represented by formula (7), a compound represented by formula (8), or a combination thereof.

[Formula 6]

In Formula 6, R is hydrogen, a C1-C10 alkyl group, or a C6-C20 aryl group, and L ₁ is hydrogen, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, or its a combination, and A represents, independently of each other, a chemical bond or -CH ₂ -,

[Formula 7]

In Formula 7, L ₁ is hydrogen, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, —CH ₂ CH ₂ NHC(=O)OL ₂ , —(CH ₂ ) _k OC(=O)L ₃ , or -(CH ₂ ) _k O(=O)NH-(CH ₂ )O(C=O)(C=CH ₂ )R, or a combination thereof, R is hydrogen; C1-C10 alkyl group or C6-C20 aryl group, k is an integer of 1 to 5;

L ₂ and L ₃ are each independently hydrogen, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, or a combination thereof,

[Formula 8]

In Formula 8, L ₁ is hydrogen, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, or a combination thereof.

The first monomer is, for example, a compound represented by Formula 3 or a compound represented by Formula 3-1.

[Formula 3]

[Formula 3-1]

In Formulas 3 and 3-1, EG is a residue derived from ethylene glycol, DEG is a residue derived from diethylene glycol, TMP is a residue derived from trimethylolpropane, and a, b and c are each independently 1 an integer of 7 to 7, an integer of 1 to 5, or an integer of 2 to 4, and l, m and n are each independently an integer of 1 to 20, or an integer of 1 to 10.

In Formulas 3 and 3-1, EG is, for example, -(OCH ₂ CH ₂ )-, and DEG is, for example, -(CH ₂ OCH ₂ )-. And in Formulas 3 and 3-1, TMP is, for example, -C{(CH ₂ O) _k (CH ₃ CH ₂ )} _z -, k is a number from 1 to 10, 1 to 8, or 1 to 5; z is a number from 1 to 10, from 1 to 10, from 1 to 8, or from 1 to 5.

As the first monomer, a compound represented by Formula 4 or a compound represented by Formula 5 may be used.

[Formula 4]

In Formula 4, EG is a residue derived from ethylene glycol, DEG is a residue derived from diethylene glycol, TMP is a residue derived from trimethylolpropane, and l, m, and n are independently integers from 1 to 20. ego,

[Formula 5]

In Formula 5, EG is a residue derived from ethylene glycol, DEG is a residue derived from diethylene glycol, TMP is a residue derived from trimethylolpropane, and l, m, and n are independently integers from 1 to 20. am.

In formulas 4 and 5, EG is for example -(OCH ₂ CH ₂ )-, DEG is for example -(CH ₂ OCH ₂ )-, and TMP is for example -C{(CH ₂ O) _k ( CH ₃ CH ₂ )} _z -, k is a number from 1 to 10, 1 to 8, or 1 to 5 and z is a number from 1 to 10, 1 to 10, 1 to 8, or 1 to 5.

The second monomer is, for example, a linear acrylate such as a compound (hexyl acrylate) represented by the following formula (9), butyl acrylate, pentyl acrylate, propyl acrylate, or a combination thereof.

[Formula 9]

The coating layer may further include a lithium salt.

The lithium salt includes, for example, salts such as LiPF ₆ , LiBF ₄ , LiFSI, and LiTFSI. FSI stands for bis(fluorosulfonyl)imide and TFSI stands for bis(trifluoromethanesulfonyl)imide. When the coating layer further includes a lithium salt, the ionic conductivity of the composite electrolyte may be further improved.

Since the composite electrolyte contains the cross-linked polymer, chain mobility is improved and lithium ions move smoothly, so that ion conductivity can be improved.

As the separator constituting the composite electrolyte, an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally 0.01 to 10 μm, and the thickness is generally 5 to 20 μm. Specific examples of the separator include polyethylene, polypropylene, polyimide, or a multilayer film of two or more layers thereof, a polyethylene/polypropylene two-layer separator, a polyethylene/polypropylene/polyethylene three-layer separator, and polypropylene/polyethylene/polypropylene 3 and mixed multilayer films such as layer separators and the like.

An electrolyte containing a lithium salt and an organic solvent may be further added to the separator.

The composite electrolyte and/or the polymer electrolyte may further include an organic solvent capable of dissolving the lithium salt. The organic solvent further includes at least one selected from a carbonate-based compound, an ether-based compound, a glyme-based compound, and an ester-based compound.

The carbonate-based solvent is, for example, ethylene carbonate, propylene carbonate, dimethyl carbonate, fluoroethylene carbonate, diethyl carbonate, or ethylmethyl carbonate.

The glyme solvent is, for example, poly(ethylene glycol) dimethyl ether (PEGDME, polyglyme), tetra(ethylene glycol) dimethyl ether (TEGDME, tetraglyme), tri (ethylene glycol) dimethyl ether (tri(ethylene glycol) dimethyl ether, triglyme), poly(ethylene glycol) dilaurate (PEGDL), poly(ethylene glycol) monoacrylate (poly(ethylene glycol) ) monoacrylate; PEGMA), and poly(ethylene glycol) diacrylate (poly(ethylene glycol) diacrylate; PEGDA).

Examples of the dioxolane-based compound include 3-dioxolane, 4,5-diethyl-dioxolane, 4,5-dimethyl-dioxolane, 4-methyl-1,3-dioxolane and 4-ethyl There is at least one selected from the group consisting of -1,3-dioxolane.

The organic solvent includes 2,2-dimethoxy-2-phenylacetophenone, dimethoxyethane, diethoxyethane, tetrahydrofuran, gamma butyrolactone, and the like.

In the composite electrolyte according to an embodiment, the thickness ratio of the polymer electrolyte and the coating film is 1:0.1 to 1:5, 1:0.12 to 1:3, 1:0.2 to 1:2.5, 1:0.3 to 1:2, or 1: 1.5 to 1:2. When the thickness ratio of the polymer electrolyte and the coating film is within the above range, a composite electrolyte having excellent ionic conductivity and strength can be obtained, and high-temperature storage characteristics are improved without deterioration of the lifespan of a lithium metal battery employing the composite electrolyte.

The ionic conductivity of the composite electrolyte is 1 X 10 ^-6 S/cm or more, 1 X 10 ^-4 S/cm or more, for example 5×10 ^-4 S/cm or more, specifically 1 at about 25° C. or 60° C. ×10 ^-3 S/cm or more, for example, may be 1 X 10 ^-6 S/cm to 1 X 10 ^-4 S/cm.

The composite electrolyte according to one embodiment has a puncture strength of 100 gf or more, 100 to 300 gf, for example, 150 to 250 gf.

Hereinafter, a method for manufacturing a composite electrolyte according to an embodiment will be described.

First, a first monomer having at least two double bonds and a second monomer having one or more double bonds in a separator; lithium salt; and coating and curing a polymer electrolyte composition including a nitrile-based compound to form a polymer electrolyte on the separator.

The mixing weight ratio of the first monomer and the second monomer is 95:5 (19:1) to 20:80 (1:4), for example, 10:1 to 1:1, 8:1 to 2:1, 5: 1-4:1, or 70:30 (2.3:1). When the mixing weight ratio of the first monomer and the second monomer is within the above range, a composite electrolyte having excellent ionic conductivity and strength can be obtained, and high-temperature storage characteristics are improved without deterioration of the lifespan of a lithium metal battery employing the composite electrolyte.

For the polymer electrolyte composition, for example, a first mixture is obtained by mixing a first monomer and a second monomer, and a second mixture is prepared by separately mixing a lithium salt and a nitrile-based compound, and the first mixture and the second mixture are mixed. It can be obtained according to the step of mixing. When the first mixture and the second mixture are mixed at a temperature of, for example, 20 to 70°C, or 30 to 65°C, a polymer electrolyte composition having a more uniform composition can be obtained.

The content of the nitrile-based compound in the polymer electrolyte composition is 10 to 70 parts by weight based on 100 parts by weight of the first monomer. And the content of the lithium salt is 10 to 50 parts by weight based on 100 parts by weight of the first monomer.

The polymer electrolyte composition may include a polymerization initiator by heat or light.

A method of forming a coating film on both surfaces of the polymer electrolyte includes, for example, the following two manufacturing methods.

According to the first manufacturing method, a desired composite electrolyte can be formed by forming a coating film/polymer electrolyte/coating film using a release film and then removing the release film.

According to the second manufacturing method, a desired composite electrolyte can be prepared by coating and curing the coating film composition on both sides of the polymer electrolyte.

The first manufacturing method will be described in more detail as follows.

A coating film composition comprising a first monomer having at least two double bonds and a second monomer having one or more double bonds and a lithium salt is applied on a release film, and a polymer electrolyte is laminated on the resultant, and then the coating film composition is applied and the curing reaction is carried out. Then, the release film is removed from the resultant to prepare a composite electrolyte including a polymer electrolyte and a coating film disposed on both sides of the polymer electrolyte.

The curing may be carried out by a polymerization reaction applying heat or light.

The coating film composition may include a polymerization initiator by heat or light.

As the thermal polymerization initiator, at least one selected from the group consisting of a persulfate-based initiator, an azo-based initiator, hydrogen peroxide, and ascorbic acid may be used.

The photopolymerization initiator is, for example, an acetophenone-based compound; benzophenone compounds; thioxanthone-based compounds; benzoin compounds; A triazine-based compound or the like can be used. The content of the polymerization initiator is, for example, 0.01 to 10 parts by weight, for example, 0.2 to 5 parts by weight based on 100 parts by weight of the total composition weight.

The release film serves to support the composition for forming a coating film, and as a non-limiting example, a polyethylene terephthalate film, a mylar film, and the like may be used.

According to the second manufacturing method, a coating film composition comprising a first monomer having two double bonds and a second monomer having one or more double bonds is applied to at least one surface of the polymer electrolyte obtained according to the first step and curing reaction to prepare a composite electrolyte. The coating film composition may be applied to both sides of the polymer electrolyte, for example.

A lithium metal battery includes a battery case including a positive electrode, a negative electrode, and a composite electrolyte interposed therebetween, and accommodating them.

For example, the lithium metal battery may be manufactured by the following method.

First, an anode is prepared. For example, a positive electrode active material composition in which a positive electrode active material, a conductive agent, a binder, and a solvent are mixed is prepared. The positive electrode active material composition is directly coated on a metal current collector to manufacture a positive electrode plate. Alternatively, the positive electrode active material composition may be cast on a separate support, and then a film peeled from the support may be laminated on a metal current collector to manufacture a positive electrode plate. The positive electrode is not limited to the above-listed shapes and may be in a shape other than the above-mentioned shapes.

The positive active material is a lithium composite oxide, and any one commonly used in the art may be used without limitation.

As a positive electrode active material for manufacturing a positive electrode, it 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, but is not necessarily limited thereto and any positive active material available in the art may be used.

The positive active material may be, for example, one or more of a complex oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof, and specific examples thereof include Li _a A _1-b B _b D ₂ (wherein 0.90 ≤ a ≤ 1.8, and 0 ≤ b ≤ 0.5); Li _a E _1-b B _b O _2-c D _c (in the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); LiE _2-b B _b O _4-c D _c (wherein 0 ≤ b ≤ 0.5 and 0 ≤ c ≤ 0.05); Li _a Ni _1-bc Co _b B _c D _α (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li _a Ni _1-bc 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-bc Co _b B _c O _2-α F ₂ (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α <2); Li _a Ni _1-bc Mn _b B _c D _α (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li _a Ni _1-bc 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 _1-bc Mn _b B _c O _2-α F ₂ (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 (in the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1); Li _a Ni _b Co _c Mn _d GeO ₂ (in the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0.001 ≤ e ≤ 0.1); Li _a NiG _b O ₂ (in the above formula, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li _a CoG _b O ₂ (in the above formula, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li _a MnG _b O ₂ (in the above formula, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); 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); Li _(3-f) Fe ₂ (PO ₄ ) ₃ (0 ≤ f ≤ 2); A compound represented by any one of the formulas of LiFePO _{4 may 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 a combination 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.

Of course, a compound having a coating layer on the surface of the compound may be used, or a mixture of the compound and a compound having a coating layer may be used. The coating layer may include a coating element compound of oxide or hydroxide of the coating element, oxyhydroxide of the coating element, oxycarbonate of the coating element, or hydroxycarbonate of the coating element. The compound constituting these coating layers may be amorphous or crystalline. As the coating element included in the coating layer, Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or a mixture thereof may be used. In the coating layer forming process, any coating method may be used as long as the compound can be coated by a method that does not adversely affect the physical properties of the positive electrode active material (eg, spray coating, dipping, etc.) by using these elements in the compound. Since the content can be well understood by those engaged in the field, a detailed description thereof will be omitted.

As the cathode active material, for example, a compound represented by the following Chemical Formula 10, a compound represented by the following Chemical Formula 11, or a compound represented by the Chemical Formula 12 may be used.

[Formula 10]

Li _a Ni _b Co _c Mn _d O ₂

In Formula 10, when 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, the sum of b, c and d is 1, and b, c and d are 0 at the same time is excluded,

[Formula 11]

Li ₂ MnO ₃

[Formula 12]

LiMO ₂

In Formula 12, M is Mn, Fe, Co, or Ni.

Examples of the conductive agent include carbon black, graphite fine particles, natural graphite, artificial graphite, acetylene black, Ketjen black, carbon fiber; metal powder or metal fibers or metal tubes such as carbon nanotubes, copper, nickel, aluminum, and silver; Conductive polymers such as polyphenylene derivatives may be used, but are not limited thereto, and any conductive agent may be used in the art.

Examples of the binder include vinylidene fluoride/hexafluoropropylene copolymer, polyvinylidene fluoride, polyimide, polyethylene, polyester, polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene (PTFE), A carboxymethyl cellulose-styrene-butadiene rubber (SMC/SBR) copolymer, a styrene-butadiene rubber-based polymer, or a mixture thereof may be used. The binder is not limited thereto, and any binder that can be used as a binder in the art may be used.

As the solvent, N-methylpyrrolidone, acetone, or water may be used, but the solvent is not limited thereto and any solvent that can be used in the art may be used.

The content of the positive electrode active material, the conductive agent, the binder and the solvent is a level commonly used in a lithium metal battery. At least one of the conductive agent, the binder, and the solvent may be omitted depending on the use and configuration of the lithium metal battery.

Next, a lithium metal thin film or a lithium alloy thin film is prepared as a lithium negative electrode.

As the lithium metal anode, a lithium metal thin film or a lithium metal alloy thin film may be used. The thickness of the lithium metal thin film or the lithium metal alloy thin film may be 100 μm or less. For example, the lithium battery may have stable cycle characteristics even with respect to a lithium metal thin film or a lithium metal alloy thin film having a thickness of 100 μm or less. For example, in the lithium battery, the thickness of the lithium metal thin film or the lithium metal alloy thin film may be 80 μm or less, for example 60 μm or less, specifically 0.1 to 60 μm.

The lithium metal battery uses a composite electrolyte according to an embodiment as an electrolyte.

In addition to the above-described electrolyte in the lithium metal battery according to an embodiment, one or more selected from a liquid electrolyte, a solid electrolyte, a gel electrolyte, and a polymer ionic liquid may be further used.

According to another embodiment, the lithium metal battery may further include a liquid electrolyte, at least one selected from a solid electrolyte, a gel electrolyte, and a polymer ionic liquid, and a separator.

The liquid electrolyte further includes at least one selected from an organic solvent, an ionic liquid, and a lithium salt. Any organic solvent can be used as long as it is commonly used in lithium metal batteries, and non-limiting examples include a carbonate-based compound, a glyme-based compound, and a dioxolane-based compound.

The gel electrolyte may be used as long as it is well known in the art as an electrolyte having a gel form.

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.

An ionic liquid has a melting point below room temperature and refers to a salt in a liquid state at room temperature or a molten salt at room temperature composed of only ions. Ionic liquids are for example N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide N-butyl-N-methylpyrrolidium bis(3-trifluoromethylsulfonyl)imi de, at least one selected from the group consisting of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide am.

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

Examples of the organic solid electrolyte include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphoric acid ester polymers, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, polymers containing ionic dissociation groups, etc. can be used

The inorganic solid _{electrolyte, Cu 3 N, Li 3 N} , LiPON, Li 3 PO 4 .Li 2 S.SiS 2, Li 2 S.GeS 2 .Ga 2 S 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 , NLi _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,Al,Ga) _x (Ge _1-y Ti _y ) _2-x (PO ₄ ) ₃ (0≤X≤0.8, 0≤Y≤1.0, M is Nd, Sm, Eu, Gd, Tb, Dy , Ho, Er, 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 or Ta), Li _7+x A _x La _3-x Zr ₂ O ₁₂ (0<x<3, A is Zn) and the like may be used.

Polymeric ionic liquids according to one embodiment are i) ammonium-based, pyrrolidinium-based, pyridinium-based, pyrimidinium-based, imidazolium-based, piperidinium-based, pyrazolium-based, oxazolium-based, pyridazinium-based, phospho At least one cation selected from nium-based, sulfonium-based, triazolium-based and mixtures thereof, and ii) 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 ^- may contain a repeating unit comprising at least one anion selected from among.

The lithium metal battery according to one embodiment has excellent capacity and lifespan characteristics, so it can be used in a battery cell used as a power source for a small device, as well as a medium or large battery pack including a plurality of battery cells used as a power source for a medium or large device. It can also be used as a unit cell in a battery module.

As shown in FIG. 5 , a lithium metal battery 51 according to an embodiment includes a positive electrode 53 , a lithium negative electrode 52 , and a composite electrolyte 54 according to an embodiment. The above-described positive electrode 53 , negative electrode 52 , and composite electrolyte 54 are wound or folded and accommodated in the battery case 55 . Next, the electrolyte according to an embodiment is injected into the battery case 55 and sealed with a cap assembly to complete the lithium metal battery 51 . The battery case may have a cylindrical shape, a prismatic shape, or a thin film type. For example, the lithium metal battery may be a large-sized thin-film battery. The lithium metal battery may be a lithium ion battery.

Since the lithium metal battery has excellent lifespan characteristics and high rate characteristics, it can be used in medium and large-sized devices. Examples of mid-to-large devices include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and the like. -bike) and an electric two-wheeled vehicle power tool power storage device including an electric scooter (E-scooter), but is not limited thereto. In addition, it can be used in fields requiring a large amount of power storage. For example, it can be used for electric bicycles, power tools, and the like.

It will be described in more detail through the following examples and comparative examples. However, the examples are for illustrative purposes and are not limited thereto.

(Production of composite electrolyte)

Example 1

The compound (DRIC) represented by Formula 4-1 and hexyl acrylate were mixed in a 5:2 weight ratio, and succinonitrile (SN) in which LiTFSI was dissolved in 3M was added and mixed. When dissolving LiTFSI in SN, after liquefying SN in an oven at 60° C., LiTFSI was added and then dissolved. Here, the total content of SN in which LiTFSI is dissolved in 3M, the compound represented by Formula 4-1, and hexyl acrylate are mixed in a 3:1 weight ratio, and 2,2'-azobis(2,4-dimethyl) as a polymerization initiator Valeronitrile) was added and mixed to obtain a polymer electrolyte composition. Here, the content of the polymerization initiator is 0.1 parts by weight based on 100 parts by weight of the total of the compound represented by Formula 4-1 and hexyl acrylate.

<Formula 4-1>

In Formula 4-1, EG is a residue derived from ethylene glycol -(OCH ₂ CH ₂ )-, DEG is a residue derived from diethylene glycol -(CH ₂ OCH ₂ )-, and TMP is trimethylolpropane As a residue derived from, -C(CH ₂ O)(CH ₃ CH ₂ )-, L is 5, m is 5, and n is 5.

The polymer electrolyte composition was coated on a nonwoven fabric separator (Hirose, thickness: 35um) by a doctor blade method, and then cured by UV irradiation. Then, the resultant was dried to form a polymer electrolyte with a thickness of about 40 um on the inside and surface of the nonwoven membrane.

에서 부가 및 용해한 다음 여기에 상기 화학식 4-1로 표시되는 화합물 및 중합개시제인 2,2'-아조비스(2,4-디메틸발레로니트릴를 부가 및 혼합하여 코팅막 조성물을 얻었다. 코팅막 조성물에서 화학식 4-1로 표시되는 화합물(DRIC) 및 헥실아크릴레이트의 혼합비는 5:2 중량비이고, 중합개시제의 함량은 화학식 4-1의 화합물 100 중량부 대비 0.1 중량부이다.Separately, 15 parts by weight of LITFSI to 85 parts by weight of hexyl acrylate 25 parts by weight

After addition and dissolution in the above formula 4-1 and 2,2'-azobis(2,4-dimethylvaleronitrile), which is a polymerization initiator, were added and mixed thereto to obtain a coating film composition. In the coating film composition, formula 4 The mixing ratio of the compound (DRIC) represented by -1 and the hexyl acrylate is 5:2 by weight, and the content of the polymerization initiator is 0.1 parts by weight based on 100 parts by weight of the compound of Formula 4-1.

A coating film composition was applied on a PET film, which is a release film, and a polymer electrolyte was laminated thereon, and then the coating film composition was applied. Then, a PET film, which is a release film, was laminated on the resulting product. Then, the resultant is cured by irradiating UV and removing the release film to obtain a composite electrolyte having a laminate structure of coating film (thickness: 30 µm)/polymer electrolyte (thickness: 40 µm)/coating film (thickness: 30 µm) prepared.

Example 2-3

A composite electrolyte was prepared in the same manner as in Example 1, except that the thickness of the coating film and the polymer electrolyte was changed as shown in Table 1 below.

Comparative Example 1

The compound (DRIC) represented by Formula 4-1 and hexyl acrylate were mixed in a weight ratio of 5:2, and succinonitrile (SN) in which LiTFSI was dissolved in 3M was added and mixed. When dissolving LiTFSI in SN, after liquefying SN in an oven at 60° C., LiTFSI was added and then dissolved. Here, the total content of SN in which LiTFSI was dissolved in 3M, the compound represented by Formula 4-1 and hexyl acrylate used in Example 1 were mixed in a 3:1 weight ratio, and 2,2'-azobis as a polymerization initiator was mixed. (2,4-dimethylvaleronitrile was added and mixed to obtain a polymer electrolyte composition. The content of the polymerization initiator was 0.1 parts by weight based on 100 parts by weight of the total of the compound represented by Formula 4-1 and hexyl acrylate.

The polymer electrolyte composition was coated on a nonwoven fabric separator (Hirose, thickness: 35 um) by a doctor blade method, and then cured by UV irradiation. Then, the resultant was dried to form a polymer electrolyte having a thickness of about 40 um on the inside and the surface of the nonwoven separator.

Comparative Example 2

A 7 wt% solution in which KF9300, a PVdF-based binder, was dissolved in acetone and DMAc mixed solvent, and a 10 wt% solution in which 21216 binder was dissolved in acetone were prepared, respectively. Alumina (LS235, Japan Light Metals) was added to acetone in an amount of 25% by weight and then dispersed with beads milling for 3 hours to prepare an alumina dispersion. The binder solution and the alumina dispersion were mixed so that the weight ratio of the binder solid content to the alumina solid content was 1/6 so that the weight ratio of the above KF9300 and 21216 binders was 5/5, and acetone was added so that the total solid content was 11% by weight. A coating solution was prepared. A coating separator having a total thickness of about 16 μm was manufactured using a coating solution of a polyethylene fabric (SK) having a thickness of 12 μm.

Comparative Example 3

An electrolyte was prepared in the same manner as in Comparative Example 2, except that a nonwoven fabric was used instead of the alumina-coated nonwoven fabric.

division Total thickness of composite electrolyte (㎛) Polyelectrolyte thickness (㎛) Total thickness of coating film (㎛) Example 1 100 60 40 Example 2 45 5 40 Example 3 140 50 40 Comparative Example 1 100 100 - Comparative Example 2 40 100 - Comparative Example 3 40 100 -

(Preparation of cells)

Production example 1

In a manner to confirm the durability and ionic conductivity of the composite electrolytes of Examples 1 to 3 and the electrolytes of Comparative Examples 1 to 3 as cell characteristics, 50 μm thick lithium metal (Li metal) was placed on the upper and lower portions of the composite electrolyte Thus, a Li-Li symmetric cell was prepared.

Production Examples 2 to 3

A Li-Li symmetric cell was manufactured in the same manner as in Preparation Example 1, except that the polymer electrolyte of Examples 2 to 3 was used instead of the polymer electrolyte of Example 1.

Comparative Production Example 1 to Comparative Production Example 3

A Li-Li symmetric cell was prepared in the same manner as in Preparation Example 1, except that the polymer electrolytes of Comparative Examples 1 to 3 were respectively used instead of the polymer electrolyte of Example 1.

Evaluation Example 1: Pricking strength evaluation

In order to measure the puncture strength of the composite electrolytes of Examples 1 to 3 and the electrolytes of Comparative Examples 1 to 3, the following experiment was performed.

Each of the separators prepared in Examples and Comparative Examples was cut at 10 different points to have a width (MD) 50 mm Х length (TD) 50 mm, and 10 specimens were prepared, and then using the GATO Tech G5 equipment After placing the specimen on a hole having a diameter of 10 cm, the force of piercing was measured while pressing it with a probe having a diameter of about 1 mm. The puncture strength of each specimen was measured three times, and then the average value was calculated.

Evaluation Example 2: High-temperature ionic conductivity

에서 solartron 社 multistate analyzer를 이용하여 이온전도도를 측정하였다.60 for the composite electrolytes of Examples 1 to 3 and the electrolytes of Comparative Examples 1 to 3

ion conductivity was measured using a solartron multistate analyzer.

Evaluation Example 3: High Temperature Storage

After the Li-Li symmetric cells of Preparation Examples 1 to 3 and the Li-Li symmetric cells of Comparative Preparation Examples 1 to 3 were stored in an oven at 60° C. for 48 hours, the cells were disassembled and surface properties were checked to evaluate high-temperature storage properties.

High-temperature storage is divided into Pass and Fail. Pass is when the shape of the polymer electrolyte does not change and the lithium metal surface is not damaged, and Fail is when the color of the lithium metal surface turns yellow when the polymer electrolyte is melted and deformed.

2 and 3 are photographs showing the surface characteristics after disassembling the cell of Preparation Example 1 and the cell of Comparative Preparation Example 1, respectively.

Evaluation Example 4: Lifetime Characteristics

In a manner to confirm the durability and ionic conductivity of the composite electrolytes of Examples 1 to 3 and the electrolytes of Comparative Examples 1 to 3 as cell characteristics, 50 μm thick lithium metal (Li metal) was placed on the upper and lower portions of the composite electrolyte Thus, a Li-Li symmetric cell was prepared.

The driving condition of the Li-Li symmetric cell is 60° C., and the charging/discharging conditions are as described later.

Charging and discharging were repeated twice for 1 hour at a constant current of 0.05 mA at 60°C, and charging and discharging were repeated twice for 1 hour at a constant current of 0.1 mA. Then, charging and discharging were repeatedly performed 47 times for 1 hour at a constant current of 0.05 mA, for a total of 51 cycles.

As for the lifespan characteristics, the case where the discharge capacity of 51 cycles was 80% or more compared to the discharge capacity of one cycle was indicated as “good”.

Table 2 below shows the evaluation results of the puncture strength and high-temperature conductivity of the composite electrolyte, and the high-temperature storage and lifespan of the Li-Li symmetric cell.

division Puncture strength (gf) high temperature storage life span(%) Example 1 (Production Example 1) 200 Pass Good Example 2 (Production Example 2) 151 Pass Good Example 3 (Production Example 3) 248 Pass Good Comparative Example 1 (Comparative Production Example 1) 96 Fail Good Comparative Example 2 (Comparative Production Example 2) 74 Fail Good Comparative Example 3 (Comparative Production Example 3) 147 Fail Good

Referring to Table 2, it can be seen that the composite electrolytes of Examples 1 to 3 have improved puncture strength compared to the electrolytes of Comparative Examples 1 to 3. In particular, the composite electrolytes of Examples 1 to 3 exhibited a puncture strength higher than that of the PET-based non-woven fabric separator (ir 130 gf) at a level of 150 gf or more.

In addition, the Li-Li symmetric cells of Preparation Examples 1 to 3 have significantly improved high-temperature storage properties compared to the Li-Li symmetric cells of Comparative Preparation Examples 1 to 3.

Evaluation Example 5: Voltage Profile

In a manner to check the durability and ionic conductivity of the composite electrolytes of Examples 1 to 3 and the electrolytes of Comparative Examples 1 to 3 as cell characteristics, 50 μm thick lithium metal (Li metal) is placed on the upper and lower portions of the composite electrolyte Thus, a Li-Li symmetric cell was prepared.

The driving condition of the Li-Li symmetric cell is 60° C., and the charging/discharging conditions are as described later.

Charging and discharging were repeated twice for 1 hour at a constant current of 0.05 mA at 60°C, and charging and discharging were repeated twice for 1 hour at a constant current of 0.1 mA. Then, charging and discharging were repeatedly performed 47 times for 1 hour at a constant current of 0.05 mA, for a total of 51 cycles.

The evaluation conditions are shown in FIG. 4 .

As shown in FIG. 4 , it was found that the discharge voltage characteristics of the symmetric cells employing the composite electrolytes of Examples 1 to 3 were improved over time.

In the above, one embodiment has been described with reference to the drawings and embodiments, but this is only an example, and those of ordinary skill in the art can understand that various modifications and equivalent other embodiments are possible therefrom. will be. Accordingly, the protection scope of the present invention should be defined by the appended claims.

51: lithium metal battery 52: lithium negative electrode
53: positive electrode 54: composite electrolyte
55: battery case

Claims (16)

It is a composite electrolyte for a lithium metal battery including a lithium negative electrode,
The composite electrolyte comprises: a cross-linked polymer comprising i) a separator, ii) a first monomer having at least two double bonds and a second monomer having one or more double bonds on the separator; lithium salt; And a polymer electrolyte comprising a nitrile-based compound,
It is disposed on at least one surface of the polymer electrolyte and comprises a coating film containing a crosslinked polymer of a first monomer having two or more double bonds and a second monomer having one or more double bonds,
The first monomer contains at least three or more repeating units represented by the formula (1), and is a compound in which one selected from the group represented by the following formula (2) is bonded to both ends of the repeating unit, a composite electrolyte for a lithium metal battery:
[Formula 1]

,
In Formula 1, E is ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, diethylene glycol, alkanediol, ethoxylated alkanediol, propoxylated alkanediol , trimethylolpropane, ethoxylated trimethylolpropane, propoxylated trimethylolpropane, ditrimethylolpropane, ethoxylated ditrimethylolpropane, propoxylated ditrimethylolpropane, pentaerythritol, ethoxyl Lated pentaerythritol, propoxylated pentaerythritol, dipentaerythritol, ethoxylated dipentaerythritol, propoxylated dipentaerythritol, bisphenol A, ethoxylated bisphenol A, propoxylate It is a residue derived from a group selected from tide bisphenol A and combinations thereof, and n of each repeating unit is independently an integer from 1 to 20;
[Formula 2]

,

,

,

,

,

,

,
In Formula 2, R is independently a hydrogen atom, a C1-C10 alkyl group, a C6-C20 aryl group, or a combination thereof. The composite electrolyte for a lithium metal battery according to claim 1, wherein the coating film has a thickness of 5 μm to 100 μm. The composite electrolyte for a lithium metal battery according to claim 1, wherein the first monomer is a compound represented by Formula 3 or a compound represented by Formula 3-1:
[Formula 3]

[Formula 3-1]

In Formulas 3 and 3-1, EG is a residue derived from ethylene glycol,
DEG is a residue derived from diethylene glycol, TMP is a residue derived from trimethylolpropane,
a, b and c are each independently an integer from 1 to 7, and l, m and n are each independently an integer from 1 to 20. The composite electrolyte for a lithium metal battery according to claim 1, wherein the first monomer is a compound represented by the following formula (4) or a compound represented by formula (5):
[Formula 4]

In Formula 4, EG is a residue derived from ethylene glycol,
DEG is a residue derived from diethylene glycol, TMP is a residue derived from trimethylolpropane,
l, m and n are each independently an integer from 1 to 20,
[Formula 5]

In Formula 5, EG is a residue derived from ethylene glycol, DEG is a residue derived from diethylene glycol, TMP is a residue derived from trimethylolpropane,
l, m and n are each independently an integer from 1 to 20. The composite electrolyte for a lithium metal battery according to claim 1, wherein the second monomer is a compound represented by Formula 6, a compound represented by Formula 7, a compound represented by Formula 8, or a combination thereof.
[Formula 6]

In Formula 6, R is hydrogen, a C1-C10 alkyl group, or a C6-C20 aryl group, and L ₁ is hydrogen, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, or its a combination, and A represents, independently of each other, a chemical bond or -CH ₂ -,
[Formula 7]

In Formula 7, L ₁ is hydrogen, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, —CH ₂ CH ₂ NHC(=O)OL ₂ , —(CH ₂ ) _k OC(=O)L ₃ , or -(CH ₂ ) _k O(=O)NH-(CH ₂ )O(C=O)(C=CH ₂ )R, or a combination thereof, R is hydrogen; C1-C10 alkyl group or C6-C20 aryl group, k is an integer of 1 to 5;
L ₂ and L ₃ are each independently hydrogen, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, or a combination thereof,
[Formula 8]

In Formula 8, L ₁ is hydrogen, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, or a combination thereof. The composite electrolyte for a lithium metal battery according to claim 1, wherein the second monomer is a compound represented by the following Chemical Formula 9, butyl acrylate, propyl acrylate, pentyl acrylate, or a combination thereof.
[Formula 9]

The composite electrolyte for a lithium metal battery according to claim 1, wherein the separator is polypropylene, polyethylene, polyimide, or a combination thereof. According to claim 1, wherein the nitrile-based compound succinonitrile (succinonitrile), glutaronitrile (glutaronitrile), adiponitrile (adiponitrile), pimelonitrile (pimelonitrile), suberonitrile (suberonitrile) or a combination thereof A composite electrolyte for a lithium metal battery that includes. The composite electrolyte for a lithium metal battery according to claim 1, wherein a thickness ratio of the polymer electrolyte and the coating film is 1:0.1 to 1:5. The composite electrolyte for a lithium metal battery according to claim 1, wherein the mixing weight ratio of the first monomer and the second monomer is 95:5 to 20:80. The composite electrolyte for a lithium metal battery according to claim 1, wherein the coating layer further comprises a lithium salt. anode; lithium negative electrode; and the composite electrolyte of any one of claims 1 to 11 interposed therebetween. The lithium metal battery according to claim 12, wherein the lithium metal battery is an all-solid-state secondary battery. a first monomer having at least two double bonds and a second monomer having one or more double bonds in the separator; lithium salt; and a first step of forming a polymer electrolyte on a separator by applying and curing a polymer electrolyte composition including a nitrile-based compound; and
On at least one surface of the polymer electrolyte, a coating film containing a crosslinked polymer of a first monomer having two or more double bonds and a second monomer having one or more double bonds is formed to form a coating film according to any one of claims 1 to 11 A method for manufacturing a composite electrolyte for a lithium metal battery, comprising the second step of preparing the composite electrolyte. 15. The method of claim 14,
In the second step, a coating film composition including a first monomer having at least two double bonds and a second monomer having one or more double bonds is applied on a release film, and a polymer electrolyte is laminated on the resultant applying the coating film composition and performing a curing reaction; and
A method for manufacturing a composite electrolyte for a lithium metal battery comprising the step of preparing a composite electrolyte by removing the release film from the resultant. 15. The method of claim 14,
In the second step, a coating film composition comprising a first monomer having two double bonds and a second monomer having one or more double bonds on at least one surface of the polymer electrolyte obtained according to the first step is applied and cured. A method for producing a composite electrolyte for a lithium metal battery comprising the step of preparing a composite electrolyte by carrying out the method.

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