Electrolyte for lithium metal battery and lithium metal battery comprising the same

Abstract

An electrolyte for lithium metal batteries and a lithium metal battery comprising the electrolyte are provided. The electrolyte for lithium metal batteries comprises: a lithium salt; an organic solvent; and a bottle-brush polymer comprising repeating units represented by Chemical Formula 1, wherein the bottle-brush polymer has a bottle-brush structure comprising side chains in the repeating units connected to a backbone in the repeating units and arranged in an outward direction with uniform spacing between the side chains, and the side chain packing density, defined by the value of x / (x+y) in Chemical Formula 1, is 1 / 8 to 1. [Chemical Formula 1] In Chemical Formula 1, A1, A2, B, x, y, and t are as defined in the specification.

Description

[0001] This application claims priority and benefit to Korean Patent Application No. 10-2024-0176688, filed with the Korean Intellectual Property Office on December 2, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to electrolytes for lithium metal batteries and lithium metal batteries including the electrolyte. Background Technology

[0003] Lithium metal batteries are batteries that use lithium metal or lithium alloys as the negative electrode and have very high energy capacity.

[0004] However, due to the uneven current distribution on the surface of the lithium negative electrode, lithium metal batteries may form lithium dendrites as dendritic deposits, resulting in lithium being deposited only in certain areas. These lithium dendrites may reach the positive electrode and pose a risk of short-circuiting or even exploding the battery. Improvements in the safety and lifespan of lithium metal batteries are needed. Summary of the Invention

[0005] Examples provide an electrolyte for lithium metal batteries that exhibits excellent cycle stability by improving lithium-ion conductivity due to superior lithium-ion deposition characteristics on the surface of the negative electrode.

[0006] Another embodiment provides a lithium metal battery including the electrolyte for a lithium metal battery.

[0007] The embodiments provide an electrolyte for lithium metal batteries, the electrolyte comprising: a lithium salt; an organic solvent; and a bottle-brush polymer comprising repeating units represented by Chemical Formula 1, wherein the bottle-brush polymer may have a bottle-brush structure comprising side chains in the repeating units connected to a backbone in the repeating units and arranged in an outward direction and wherein the spacing between the side chains may be uniformly arranged, and the side chain packing density defined by the value of x / (x+y) in Chemical Formula 1 may be from about 1 / 8 to about 1.

[0008] [Chemical Formula 1]

[0009] In chemical formula 1, A1 and A2 can both be independent skeletons, which are linked groups formed by ring-opening of norbornene or norbornene derivatives, or linked groups derived from acrylates. B can be a side chain, which is a substituted or unsubstituted C1 to C20 alkyl group, wherein at least one -CH2- group of the alkyl group can be replaced by a substituted or unsubstituted C1 to C20 oxoalkylene group, -O-, -CO-, -CO-O-, -O-CO-, -S-, -Si-, -O-Si-, -ROR-, a linking group derived from a heterocyclic compound, or a linking group derived from bisphenol A, wherein R can be a substituted or unsubstituted C1 to C20 haloalkylene group. x can be an integer in the range of approximately 1 to approximately 500. y can be an integer in the range of approximately 0 to approximately 500. t can be an integer in the range of approximately 1 to approximately 500.

[0010] Bottle-brush polymers may include repeating units in chemical formula 1 in which y is about 0 to about 7 when x is about 1.

[0011] The side chain packing density can be about 1 / 4 to about 1.

[0012] Bottle brush polymers can have structures in which adjacent side chains are arranged in different outward orientations.

[0013] Bottle brush polymers can have flexible, curved structures or rigid, rod-like structures.

[0014] The bottle brush polymer may include at least one of a compound containing a structural unit represented by chemical formula 2, a compound containing a structural unit represented by chemical formula 3, and a compound containing a structural unit represented by chemical formula 4.

[0015] [Chemical Formula 2]

[0016] [Chemical Formula 3]

[0017] [Chemical Formula 4]

[0018] In chemical formulas 2 to 4 A1, A2, and B can be the same as those defined in Chemical Formula 1, and t1 to t3 can all be integers in the range of approximately 1 to approximately 500.

[0019] The bottle-brush polymer may include at least one of repeating units represented by chemical formula 5 and repeating units represented by chemical formula 6.

[0020] [Chemical Formula 5]

[0021] [Chemical Formula 6]

[0022] In chemical formulas 5 and 6, R' can be a substituted or unsubstituted C1 to C20 alkyl group. Both B1 and B2 can be side chains, which are substituted or unsubstituted C1 to C20 alkyl groups. At least one -CH2- group of this alkyl group can be replaced by a substituted or unsubstituted C1 to C20 oxoalkylene group, -O-, -CO-, -CO-O-, -O-CO-, -S-, -Si-, -O-Si-, -ROR-, a linking group derived from a heterocyclic compound, or a linking group derived from bisphenol A. R can be a substituted or unsubstituted C1 to C20 haloalkylene group. x1 and x2 can both be integers in the range of approximately 1 to approximately 500. y1 and y2 can both be integers in the range of approximately 0 to approximately 500, and t4 and t5 can both be integers in the range of approximately 1 to approximately 500.

[0023] In Formula 1, B may include a substituent derived from at least one compound selected from the group consisting of polyethylene glycol, polypropylene glycol, polycarbonate, polycaprolactone, and perfluoropolyether.

[0024] In chemical formula 1, B may include at least one substituent selected from chemical formulas 7-1 to 7-6.

[0025] [Chemical Formula 7-1] [Chemical Formula 7-2] [Chemical Formula 7-3] [Chemical Formula 7-4] [Chemical Formula 7-5] [Chemical Formula 7-6] In chemical formulas 7-1 to 7-6 n1 to n13 can all be integers in the range of approximately 1 to approximately 20.

[0026] Based on the total amount of electrolyte, the bottle brush polymer may be included in amounts from about 0.1 wt% to about 20 wt%.

[0027] Lithium salts may include at least one of LiSCN, LiN(CN)2, LiClO4, LiBF4, LiAsF6, LiPF6, LiCF3SO3, LiC(CF3SO2)3, LiN(SO2C2F5)2, LiN(SO2CF3)2, LiN(SO2F)2, LiSbF6, LiPF3(CF2CF3)3, LiPF3(CF3)3, and LiB(C2O4)2.

[0028] Organic solvents may include at least one selected from the group consisting of propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butenyl carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, isopropyl methyl carbonate, dipropyl carbonate, dibutyl carbonate, benzyl nitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, 1,3-dioxolane, 4-methyldioxolane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, and dimethyl ether.

[0029] Electrolytes can also include ionic liquids.

[0030] Ionic liquids may include at least one selected from the group consisting of: i) at least one cation selected from the group consisting of ammonium, pyrrolidineonium, pyridinium, pyrimidineonium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazineonium, phosphonium, strontium, and triazolium; and ii) at least one cation selected from the group consisting of BF4. - PF6 - AsF6 - SbF6 - AlCl4 - HSO4 - ClO4 - CH3SO3 - CF3CO2 - Cl - ,Br - I - F - SO4 - CF3SO3 - (FSO2)2N - (C2F5SO2)2N - (C2F5SO2)(CF3SO2)N - and (CF3SO2)2N - At least one anion selected from the group.

[0031] Another embodiment provides a lithium metal battery comprising: a negative electrode containing lithium metal or a lithium metal alloy; a positive electrode; and an electrolyte disposed between the negative electrode and the positive electrode.

[0032] The electrolyte for lithium metal batteries according to the embodiments can have the property of allowing lithium ions to be deposited uniformly and densely on the surface of the negative electrode, thereby ensuring that the lithium metal battery has excellent lithium-ion conductivity, low overvoltage and stable cycle performance. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of an example structure of a bottle brush-like polymer according to an embodiment.

[0034] Figure 2 This is a schematic diagram illustrating the variation of the structure of the bottle brush polymer according to the embodiment based on the side chain packing density.

[0035] Figure 3 This is a schematic diagram illustrating the structure of a bottle brush polymer according to an embodiment based on the side chain packing density.

[0036] Figure 4 This is a schematic diagram illustrating the degree of coordination bonding with lithium ions depending on the structure of the bottle-brush polymer according to an embodiment.

[0037] Figure 5 This is the NMR spectrum of the bottle brush polymer synthesized in Example 1.

[0038] Figure 6 This is the NMR spectrum of the bottle-brush polymer synthesized in Synthesis Example 2.

[0039] Figure 7 This is the NMR spectrum of the bottle-brush polymer synthesized in Example 3.

[0040] Figure 8A and Figure 8B All images show scanning electron microscope (SEM) analysis images of the surface of the lithium metal negative electrode according to Example 1 and Comparative Example 1 and Comparative Example 2.

[0041] Figure 9A and Figure 9B All images show scanning electron microscope (SEM) analysis images of the surface of the lithium metal negative electrode according to Examples 1 to 3.

[0042] Figure 10 A graph illustrating the cycle performance of the lithium metal battery according to Example 1 and Comparative Example 1 and Comparative Example 2.

[0043] Figure 11 The graph shows the cycle performance of lithium metal batteries according to Examples 1 to 3.

[0044] Figure 12 The graphs are from the electrochemical impedance spectroscopy (EIS) analysis of lithium metal batteries according to Example 1 and Comparative Example 1 and Comparative Example 2.

[0045] Figure 13 The graphs are from the electrochemical impedance spectroscopy (EIS) analysis of lithium metal batteries according to Examples 1 to 3 and Comparative Example 1.

[0046] Figure 14 This is a graph showing the viscosity of the electrolyte according to Example 1 and Comparative Example 1 and Comparative Example 2.

[0047] Figure 15 For the electrolytes according to Example 1 and Comparative Example 1 and Comparative Example 2 7 Li NMR analysis diagram.

[0048] Figure 16 For the electrolytes according to Examples 1 to 3 and Comparative Example 1 7 Li NMR analysis diagram.

[0049] Figure 17 A graph illustrating the rate performance of lithium metal batteries according to Examples 1 to 3 and Comparative Examples 1 and 2.

[0050] Figure 18 A graph illustrating the cycle durability of lithium metal batteries according to Examples 1 to 3 and Comparative Examples 1 and 2.

[0051] Figure 19 A graph showing the voltage change over time of lithium metal batteries according to Examples 1 to 3 and Comparative Examples 1 and 2.

[0052] Figure 20 A graph showing the coulombic efficiency of lithium metal batteries according to Examples 1 to 3 and Comparative Examples 1 and 2.

[0053] Figure 21 A diagram illustrating the nucleation overvoltage of a lithium metal battery according to Example 1 and Comparative Examples 1 and 2.

[0054] Figure 22 A graph showing the exchange current density of lithium metal batteries according to Example 1 and Comparative Example 1 and Comparative Example 2.

[0055] Figure 23 A graph showing the exchange current density of lithium metal batteries according to Examples 1 to 3 and Comparative Example 1.

[0056] Figure 24 Raman spectra of the electrolytes according to Examples 1 to 3 and Comparative Example 1. Detailed Implementation

[0057] Embodiments of this disclosure will be described in detail below so that those skilled in the art will understand them. However, this disclosure may be implemented in many different forms and is not to be construed as limited to the embodiments set forth herein.

[0058] In the accompanying drawings, the thickness of layers, films, panels, regions, etc., is exaggerated for clarity. Throughout the specification, the same reference numerals denote the same elements. It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it may be directly on said other element, or an intervening element may be present. Conversely, when an element is referred to as being "directly on" another element, no intervening element is present.

[0059] As used herein, unless otherwise specifically defined, “substitution” means that the hydrogen atoms of a compound are replaced by the following substituents: halogen atom, hydroxyl, nitro, cyano, amino, azide, amido, hydrazine, hydrazone, carbonyl, carbamoyl, thiol, ester, carboxyl or a salt thereof, sulfonic acid or a salt thereof, phosphate or a salt thereof, C1 to C30 alkyl, C2 to C30 alkenyl, C2 to C30 alkynyl, C6 to C30 aryl, C7 to C30 aralkyl, C1 to C30 alkoxy, C1 to C20 heteroalkyl, C3 to C20 heteroaryl, C3 to C20 heteroaryl, C3 to C30 cycloalkyl, C3 to C15 cycloalkenyl, C6 to C15 cycloalkynyl, C3 to C30 heterocycloalkyl, or combinations thereof.

[0060] In the following, an electrolyte for a lithium metal battery according to an embodiment is described.

[0061] The electrolyte for lithium metal batteries according to the embodiments includes: a lithium salt; an organic solvent; and a bottle brush polymer.

[0062] In the following text, reference will be made to Figures 1 to 3 Describe the structure of the bottle-brush-like polymer.

[0063] Figure 1 This is a schematic diagram of an example structure of a bottle brush-like polymer according to an embodiment.

[0064] Reference Figure 1 The bottle-brush-like polymer according to an embodiment is a polymer comprising a backbone (or "main chain") and side chains, and has a bottle-brush-like structure: the side chains are connected to the backbone and arranged in an outward direction, and the spacing between the side chains is uniform. The spacing between the side chains refers to the distance between adjacent side chains within a single polymer comprising the backbone and side chains. The bottle-brush-like polymer according to an embodiment may have a structure in which the side chains are arranged with a constant spacing between adjacent side chains.

[0065] Specifically, bottle-brush polymers can have a structure in which adjacent side chains are arranged outward in different directions.

[0066] Here, the constant spacing between sidechains applies to all sidechains that are close to each other and connected to the skeleton, regardless of the direction of the sidechains.

[0067] Figure 2 This is a schematic diagram illustrating the variation of the structure of the bottle brush polymer according to the embodiment based on the side chain packing density. Figure 3 This is a schematic diagram illustrating the structure of a bottle brush polymer according to an embodiment based on the side chain packing density.

[0068] Side chain packing density indicates how densely the side chains are arranged within a repeating unit of a polymer.

[0069] Reference Figure 2 and Figure 3 Depending on the side chain packing density, bottle brush polymers can have various structures. That is, when the side chain packing density is relatively low, bottle brush polymers can have flexible, bent structures, and when the side chain packing density is relatively high, bottle brush polymers can have rigid, rod-like structures.

[0070] In other words, the spacing between side chains (n) g The larger the n, the lower the side chain packing density, allowing the bottle brush polymer to have a more flexible and bendable structure, while the spacing between the side chains (n) g The smaller the value, the higher the side chain packing density, which allows bottle brush polymers to have a rigid rod-like structure.

[0071] Side chain packing density can be expressed as the ratio of the number of side chains attached to the backbone at regular intervals within a repeating unit of a bottle-brush polymer, relative to the backbone (or the ratio of the number of side chains attached to the backbone at regular intervals to the number of backbones). Figure 3 As can be seen, when the side chain packing density is, for example, about 1 / 4, the spacing between the side chains is relatively large, resulting in a more flexible and bendable structure. Conversely, when the side chain packing density is, for example, about 1, the spacing between the side chains is relatively small, thus reducing flexibility, and it can be seen that the bottle brush polymer has a rigid rod-like structure.

[0072] Bottle-brush-like polymers can have, for example, flexible, curved structures.

[0073] According to embodiments, when bottle-brush polymers having such various structures are used in the electrolyte of lithium metal batteries (specifically, when bottle-brush polymers having such various structures are used as additives in the electrolyte of lithium metal batteries), the bottle-brush polymers facilitate the uniform and dense deposition of lithium ions on the surface of the negative electrode during the lithium ion deposition process, thereby improving lithium ion conductivity. Therefore, lithium metal batteries with improved cycle stability can be obtained.

[0074] Figure 4 This is a schematic diagram illustrating the degree of coordination bonding with lithium ions depending on the structure of the bottle-brush polymer according to an embodiment.

[0075] Reference Figure 4 Because the bottle-brush polymer includes polar groups in its side chains that act as electron donors, these polar groups can conduct lithium ions through coordination with them. For example, bottle-brush polymers with flexible, curved structures due to their low side-chain packing density can further improve lithium-ion conductivity due to their high degree of coordination bonding with lithium ions. In other words, the bottle-brush polymer according to the embodiments has a structure that allows for good solvation of lithium ions within the electrolyte.

[0076] Bottle-brush polymers comprise repeating units represented by chemical formula 1.

[0077] [Chemical Formula 1]

[0078] In Formula 1, A1 and A2 represent the skeleton. A1 and A2 can both be independent linking groups formed by ring-opening of norbornene or norbornene derivatives, or linking groups derived from acrylates.

[0079] In Formula 1, B represents a side chain. B can be a substituted or unsubstituted C1 to C20 alkyl group, wherein at least one -CH2- group of the alkyl group can be replaced by a substituted or unsubstituted C1 to C20 oxoalkylene group, -O-, -CO-, -CO-O-, -O-CO-, -S-, -Si-, -O-Si-, -ROR-, a linking group derived from a heterocyclic compound, or a linking group derived from bisphenol A, wherein R can be a substituted or unsubstituted C1 to C20 haloalkylene group. That is, the side chain includes at least one polar group, thereby further improving lithium-ion conductivity.

[0080] In chemical formula 1, x represents the number of units (hereinafter referred to as "first units") in which the side chains are attached to the backbone (specifically, the number of consecutive first units). x can be an integer in the range of about 1 to about 500 (e.g., about 1 to about 400, about 1 to about 300, about 1 to about 200, or about 2 to about 200).

[0081] In chemical formula 1, y represents the number of units (hereinafter referred to as "second units") that have only a backbone and no side chains (specifically, the number of consecutive second units). y can be an integer in the range of about 0 to about 500 (e.g., about 0 to about 400, about 0 to about 300, or about 0 to about 200).

[0082] In Chemical Formula 1, t represents the number of repeating units consisting only of the first unit or the number of repeating units consisting of the first unit and the second unit. t can be an integer ranging from about 1 to about 500 (e.g., about 2 to about 500, about 5 to about 400, about 10 to about 300, or about 15 to about 200). Within this range of t, the length of the framework can be controlled in various ways, and when t is within the aforementioned range, the deposition characteristics of lithium ions on the surface of the negative electrode and the lithium ion conductivity can be improved.

[0083] Furthermore, in Formula 1, the following condition can be satisfied: 1 / 8 ≤ x / (x+y) ≤ 1 (e.g., 1 / 6 ≤ x / (x+y) ≤ 1). The aforementioned side-chain packing density can be defined as the value of x / (x+y) in Formula 1. That is, the ratio of the number of the first unit to the sum of the numbers of the first and second units is equal to the side-chain packing density.

[0084] In other words, within the above range, the smaller the value of x / (x+y) (i.e., the lower the side chain packing density), the larger the spacing between the side chains (i.e., a flexible bending structure can be achieved). Conversely, within the above range, the larger the value of x / (x+y) (i.e., the higher the side chain packing density), the smaller the spacing between the side chains (i.e., a rigid rod-like structure can be achieved).

[0085] Bottle-brush polymers having a structure including repeating units represented by chemical formula 1 and side chains in the repeating units arranged at constant intervals can exhibit excellent lithium-ion conductivity by uniformly and densely depositing lithium ions on the surface of the negative electrode.

[0086] For example, the bottle brush polymer may include repeating units in Formula 1 where y is about 0 to about 7 when x is about 1 (e.g., repeating units where y is about 1 to about 7 when x is about 1, or repeating units where y is about 2 to about 7 when x is about 1).

[0087] For example, a bottle brush polymer may include at least one of a compound containing a structural unit represented by chemical formula 2, a compound containing a structural unit represented by chemical formula 3, and a compound containing a structural unit represented by chemical formula 4. For example, a bottle brush polymer may be a compound containing a structural unit represented by chemical formula 3 or a compound containing a structural unit represented by chemical formula 4.

[0088] [Chemical Formula 2]

[0089] [Chemical Formula 3]

[0090] [Chemical Formula 4]

[0091] In chemical formulas 2 to 4, A1, A2, and B can be the same as those defined in chemical formula 1, and In chemical formulas 2 to 4, t1 to t3 represent the number of each structural unit, and are all integers in the range of about 1 to about 500.

[0092] Specifically, the compound containing the structural unit represented by Formula 2 has a constant inter-chain spacing represented by B, corresponding to the case where the value of x / (x+y) in Formula 1 is approximately 1 (i.e., the case where the side chain packing density is approximately 1). The compound containing the structural unit represented by Formula 3 has a constant inter-chain spacing, corresponding to the case where the value of x / (x+y) in Formula 1 is approximately 1 / 2 (i.e., the case where the side chain packing density is approximately 1 / 2). The compound containing the structural unit represented by Formula 4 has a constant inter-chain spacing, corresponding to the case where the value of x / (x+y) in Formula 1 is approximately 1 / 4 (i.e., the case where the side chain packing density is approximately 1 / 4).

[0093] For example, the bottle brush polymer may include at least one of repeating units represented by chemical formula 5 and repeating units represented by chemical formula 6.

[0094] [Chemical Formula 5]

[0095] [Chemical Formula 6]

[0096] In Formulas 5 and 6, B1 and B2 corresponding to the side chains can both be substituted or unsubstituted C1 to C20 alkyl side chains, wherein at least one -CH2- of the alkyl group can be replaced by a substituted or unsubstituted C1 to C20 oxoalkylene, -O-, -CO-, -CO-O-, -O-CO-, -S-, -Si-, -O-Si-, -ROR-, a linking group derived from a heterocyclic compound, or a linking group derived from bisphenol A, wherein R can be a substituted or unsubstituted C1 to C20 haloalkylene.

[0097] In chemical formulas 5 and 6, x1 and x2 can both be integers in the range of about 1 to about 500 (e.g., about 1 to about 400, about 1 to about 300, or about 1 to about 200).

[0098] In chemical formulas 5 and 6, y1 and y2 can both be integers in the range of about 0 to about 500 (e.g., about 0 to about 400, about 0 to about 300, or about 0 to about 200).

[0099] In chemical formulas 5 and 6, t4 and t5 can both be integers in the range of about 1 to about 500 (e.g., about 5 to about 400, about 10 to about 300, or about 15 to about 200).

[0100] In chemical formula 6, R' can be a substituted or unsubstituted C1 to C20 alkyl group.

[0101] For example, the side chain (i.e., B in Formula 1) may include substituents derived from one or more compounds selected from polyethylene glycol, polypropylene glycol, polycarbonate, polycaprolactone, and perfluoropolyether.

[0102] For example, in Formula 1, B may include at least one substituent selected from Formulas 7-1 to 7-6.

[0103] [Chemical Formula 7-1] [Chemical Formula 7-2] [Chemical Formula 7-3] [Chemical Formula 7-4] [Chemical Formula 7-5] [Chemical Formula 7-6] In chemical formulas 7-1 to 7-6, n1 to n13 can all be integers in the range of about 1 to about 20.

[0104] In Formula 1, the length of the side chains can be controlled, as specifically in the examples of Formulas 7-1 to 7-6. In addition to controlling the side chain packing density as described above, lithium-ion conductivity can be further improved by controlling the length of the side chains containing polar groups.

[0105] The bottle-brush polymer according to the embodiments can be synthesized by reacting compounds that each derive the backbone and side chains as defined in Formula 1. That is, the bottle-brush polymer according to the embodiments can be synthesized by reacting a backbone-derived compound (such as norbornene or a norbornene derivative or an acrylate) with a side-derived compound (such as a C1 to C20 alkane, wherein at least one -CH2- of the alkane includes a polar group).

[0106] Furthermore, a bottle-brush polymer with a certain range of side chain packing densities according to the embodiments can be prepared by controlling the mixing ratio of compounds synthesized from compounds that respectively derive their backbone and side chains to compounds that selectively derive their backbone. In this case, based on the total amount of the bottle-brush polymer, the former compound can be mixed in an amount of about 1 mol% to about 100 mol% (e.g., about 5 mol% to about 100 mol%, or about 10 mol% to about 100 mol%). When mixed within the above-mentioned ratio range, a bottle-brush polymer with a side chain packing density within a predetermined range is prepared, thereby improving lithium-ion conductivity by exhibiting excellent lithium-ion deposition characteristics on the surface of lithium metal.

[0107] Based on the total amount of electrolyte, the aforementioned bottle brush polymer can be included in an amount of about 0.1 wt% to about 20 wt% (e.g., about 0.5 wt% to about 15 wt% or about 0.5 wt% to about 10 wt%). When the content of the bottle brush polymer is within the above range, a lithium metal battery with excellent lithium-ion conductivity can be obtained, thereby making the lithium metal battery safe and having excellent life characteristics.

[0108] Lithium salts are substances that act as a source of lithium ions in batteries, enabling basic lithium metal batteries to operate and facilitating the movement of lithium ions between the positive and negative electrodes.

[0109] Lithium salts may include at least one of LiSCN, LiN(CN)2, LiClO4, LiBF4, LiAsF6, LiPF6, LiCF3SO3, LiC(CF3SO2)3, LiN(SO2C2F5)2, LiN(SO2CF3)2, LiN(SO2F)2, LiSbF6, LiPF3(CF2CF3)3, LiPF3(CF3)3, and LiB(C2O4)2.

[0110] The concentration of lithium salt can range from 0.1 M to 2.0 M. When the concentration of lithium salt is within the above range, lithium ions can move effectively due to the appropriate conductivity and viscosity of the electrolyte.

[0111] Any organic solvent that can be used in the relevant technical field can be used as an organic solvent.

[0112] Organic solvents may include at least one selected from, for example, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butenyl carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, isopropyl methyl carbonate, dipropyl carbonate, dibutyl carbonate, benzyl nitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, 1,3-dioxolane, 4-methyldioxolane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, and dimethyl ether.

[0113] Electrolytes can also include ionic liquids. Ionic liquids have high solubility in organic solvents and can further enhance ionic conductivity.

[0114] Ionic liquids may include at least one selected from the group consisting of: i) at least one cation selected from the group consisting of ammonium, pyrrolidineonium, pyridinium, pyrimidineonium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazineonium, phosphonium, strontium, and triazolium; and ii) at least one cation selected from the group consisting of BF4. - PF6 - AsF6 - SbF6 - AlCl4 - HSO4 - ClO4 - CH3SO3 - CF3CO2 - Cl - ,Br - I - F - SO4 - CF3SO3 - (FSO2)2N - (C2F5SO2)2N - (C2F5SO2)(CF3SO2)N - and (CF3SO2)2N - At least one anion selected from the group.

[0115] Ionic liquids may include at least one selected from, for example, N-methyl-N-propylpyrrolidone bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidone bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide.

[0116] The following text will describe lithium metal batteries that include the electrolytes described above.

[0117] The lithium metal battery according to an embodiment includes: a negative electrode comprising lithium metal or a lithium metal alloy; a positive electrode; and an electrolyte disposed between the negative electrode and the positive electrode, and comprising the electrolyte.

[0118] The lithium metal alloy used in the negative electrode can be an alloy composed of lithium and at least one metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Al and Sn.

[0119] The positive electrode may include a current collector and a layer of positive electrode active material disposed on at least one surface of the current collector. The layer of positive electrode active material may include a positive electrode active material, a binder, and a selectively conductive material.

[0120] The current collector used in the positive electrode can be, for example, aluminum, nickel, etc., but is not limited to these.

[0121] Compounds capable of reversibly inserting and deintercalating lithium can be used as positive electrode active materials. Specifically, at least one of the following can be used: a composite oxide or composite phosphorus oxide of a metal such as cobalt, manganese, nickel, aluminum, iron, or combinations thereof with lithium. More specifically, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, or combinations thereof can be used.

[0122] The binder serves to ensure good adhesion between the particles of the positive electrode active material and to the current collector. Binders may include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, polyamide-imide, polyacrylic acid, etc.

[0123] Conductive materials can be used to provide conductivity to electrodes, and any material that does not cause chemical changes and is electronically conductive can be used. Conductive materials can be, for example, natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, metal powders such as copper, nickel, aluminum or silver, metal fibers, etc., and one or more conductive materials such as polyphenylene derivatives can also be used in combination.

[0124] The lithium metal battery according to the embodiments may also include a separator.

[0125] The separator can include a polyolefin porous substrate. Polyolefin porous substrates have a large number of pores and are commonly used substrates in electrochemical devices. Polyolefin porous substrates can exhibit excellent shut-off functionality and can contribute to improved battery safety.

[0126] Polyolefin porous substrates can be selected from the group consisting of, for example, polyethylene monolayers, polypropylene monolayers, polyethylene / polypropylene bilayers, polypropylene / polypropylene / polypropylene trilayers, and polyethylene / polypropylene / polypropylene trilayers. In addition to olefin resins, polyolefin porous substrates can also include non-olefin resins, or can include copolymers of olefin monomers and non-olefin monomers.

[0127] The lithium metal battery according to the embodiment can be cylindrical, square, coin-shaped, pouch-shaped, etc., and can have any shape such as block or film type. The lithium metal battery according to the embodiment can be widely used in mobile devices, IT devices, automobiles, etc.

[0128] The embodiments are described in more detail below with reference to examples. However, these examples are exemplary, and the scope of the claims is not limited thereto.

[0129] (Preparation of bottle-brush-like polymers) Synthesis Example 1 [Reaction Scheme 1]

[0130] 8 g (0.049 mol) of cis-5-norbornene-ex-2,3-dicarboxylic anhydride (Exo-Nb), 6.39 g (0.049 mol) of 6-aminohexanoic acid, and 50 mL of toluene were mixed in a round-bottom flask equipped with a stir bar and a reflux condenser. The mixture was heated to 130 °C and refluxed overnight, cooled to room temperature, and the toluene was removed under reduced pressure using a rotary evaporator. The remaining product was dissolved in 100 mL of dichloromethane, extracted three times with 100 mL of 0.1 M HCl aqueous solution, and three times with saturated NaCl aqueous solution, and then dried. 1.525 g (0.006 mol) of the thus obtained product, 2.75 g (0.005 mol) of polyethylene glycol, and 1.44 g (0.008 mol) of (3-dimethylaminopropyl)-ethyl-carbonyldiimide hydrochloride (EDC·HCl) were mixed to prepare Nb-PEG. The remaining product was dissolved in 100 mL of dichloromethane, extracted three times with 100 mL of 0.1 M HCl aqueous solution, and then extracted three times with saturated NaCl aqueous solution, followed by drying. The prepared Nb-PEG and Exo-Nb were mixed in a certain proportion, dissolved in dichloromethane solvent, and then subjected to ring-opening polymerization under a ring-opening metathesis polymerization (ROMP) catalyst to obtain the final product.

[0131] The final product is obtained by reacting 75 mol% Exo-Nb and 25 mol% Nb-PEG in reaction scheme 1 and is a bottle-brush polymer comprising repeating units represented by chemical formula 8.

[0132] [Chemical Formula 8]

[0133] In chemical formula 8, t6 is 75.

[0134] The NMR spectrum of a bottle-brush polymer containing repeating units represented by chemical formula 8 is shown in [image / image]. Figure 5 middle. Figure 5 This is the NMR spectrum of the bottle brush polymer synthesized in Example 1.

[0135] Synthesis Example 2 In reaction scheme 1, 50 mol% of Exo-Nb and 50 mol% of Nb-PEG are reacted to synthesize a bottle-brush polymer containing repeating units represented by chemical formula 9.

[0136] [Chemical Formula 9]

[0137] In chemical formula 9, t7 is 150.

[0138] The NMR spectrum of the bottle-brush polymer containing repeating units represented by chemical formula 9 is shown in [image / image]. Figure 6 middle. Figure 6 This is the NMR spectrum of the bottle-brush polymer synthesized in Synthesis Example 2.

[0139] Synthesis Example 3 In reaction scheme 1, 100 mol% of Nb-PEG is reacted to synthesize a bottle-brush polymer containing repeating units represented by chemical formula 10.

[0140] [Chemical Formula 10]

[0141] In chemical formula 10, t8 is 300.

[0142] The NMR spectrum of a bottle-brush polymer containing repeating units represented by chemical formula 10 is shown in [image / image / etc.]. Figure 7 middle. Figure 7 This is the NMR spectrum of the bottle-brush polymer synthesized in Example 3.

[0143] (Preparation of electrolytes for lithium metal batteries) Example 1 The electrolyte was prepared by dissolving 1 M of lithium bis(fluorosulfonyl)imide (LiN(SO2F)2, LiFSI) in 1,2-dimethoxyethane (DME) and adding 0.42 mM of the bottle-brush polymer synthesized in Synthesis Example 1.

[0144] Example 2 The electrolyte was prepared in the same manner as in Example 1, except that the bottle-brush polymer synthesized in Synthesis Example 2 was used.

[0145] Example 3 The electrolyte was prepared in the same manner as in Example 1, except that the bottle-brush polymer synthesized in Synthesis Example 3 was used.

[0146] Comparison Example 1 The electrolyte was prepared in the same manner as in Example 1, except that no bottle-brush polymer was added.

[0147] Comparison Example 2 The electrolyte was prepared in the same manner as in Example 1, except that linear polyethylene glycol (PEG) was used instead of the bottle brush polymer.

[0148] Evaluation 1: SEM Analysis A half-lithium metal battery was fabricated using lithium metal as the negative electrode and a positive electrode, respectively, and the electrolytes prepared in Examples 1 to 3 and Comparative Examples 1 and 2. At 0.5 mA / cm²... 2 and 0.5mAh / cm 2 The manufactured lithium metal battery was subjected to a single charge / discharge cycle under specific conditions. SEM (scanning electron microscopy) analysis of the surface of the negative electrode was performed before and after each cycle, and the results are shown below. Figure 8A , Figure 8B , Figure 9A and Figure 9B SEM analysis was performed using a Hitachi S4800 instrument at 10.0 kV.

[0149] Figure 8A and Figure 8B All images show scanning electron microscope (SEM) analysis images of the surface of the lithium metal negative electrode according to Example 1 and Comparative Example 1 and Comparative Example 2. Figure 9A and Figure 9B All images show scanning electron microscope (SEM) analysis images of the surface of the lithium metal negative electrode according to Examples 1 to 3. Figure 8B yes Figure 8A Enlarged image, Figure 9B yes Figure 9A Enlarged image.

[0150] Reference Figure 8A and Figure 8BIt can be confirmed that, compared with Comparative Example 1, which does not use a bottle-brush polymer, and Comparative Example 2, which uses linear PEG, Example 1, in which a bottle-brush polymer according to the embodiment is added to the electrolyte and used, exhibits more uniform and dense deposition of lithium ions on the surface of the lithium metal negative electrode after one cycle. Therefore, it is expected that the cycle stability of the lithium metal battery according to the embodiment will be improved.

[0151] Additionally, refer to Figure 9A and Figure 9B It can be confirmed that the deposition characteristics of lithium ions can vary depending on the structure of the bottle-brush polymer according to the embodiments. For reference, the bottle-brush polymers used in Examples 1 to 3 have structures in which the spacing between side chains is constant and the side chain packing densities are 1 / 4, 1 / 2, and 1, respectively (as shown in Chemical Formulas 8 to 10). That is, when comparing Examples 1 to 3, it can be seen that the lower the side chain packing density, the better the deposition characteristics of lithium ions on the surface of the lithium metal negative electrode after one cycle.

[0152] Evaluation 2: Cyclic performance Through 0.5mA / cm 2 and 0.5mAh / cm 2 The lithium metal battery manufactured in Evaluation 1 was evaluated by performing 1,000 charge / discharge cycles under the specified conditions, and the results are shown in [Figure / Table / Illustration]. Figure 10 and Figure 11 middle.

[0153] Figure 10 A graph illustrating the cycle performance of the lithium metal battery according to Example 1 and Comparative Example 1 and Comparative Example 2. Figure 11 A graph illustrating the cycle performance of lithium metal batteries according to Examples 1 to 3.

[0154] Reference Figure 10 It can be confirmed that, compared with Comparative Example 1 in which a bottle brush polymer is not used and Comparative Example 2 in which linear PEG is used, the case of Example 1 in which a bottle brush polymer according to the embodiment is added to the electrolyte and used exhibits excellent cycle stability due to the absence of short circuits and low overvoltage.

[0155] Additionally, refer to Figure 11 As can be seen, compared with Examples 2 and 3, which have higher side chain packing density, Example 1, which uses the bottle brush polymer with the lowest side chain packing density, has a lower overvoltage and therefore better cycling stability.

[0156] Evaluation 3: EIS Analysis Regarding the lithium metal battery manufactured in Evaluation 1, at 0.1 mA / cm 2and 0.4mAh / cm 2 Pre-cycling was performed under the specified conditions. Following pre-cycling, electrochemical impedance spectroscopy (EIS) analysis was performed, and the results are shown below. Figure 12 and Figure 13 middle.

[0157] Using a Biologics VSP-300 potentiostat at 5 × 10⁻⁶ 5 Hz to 5×10 -1 EIS analysis was performed using a frequency of Hz and an amplitude of 10mV.

[0158] Figure 12 The graphs are from the electrochemical impedance spectroscopy (EIS) analysis of lithium metal batteries according to Example 1 and Comparative Example 1 and Comparative Example 2. Figure 13 The graphs are from the electrochemical impedance spectroscopy (EIS) analysis of lithium metal batteries according to Examples 1 to 3 and Comparative Example 1.

[0159] Reference Figure 12 It can be confirmed that, compared with Comparative Example 1, in which a bottle-brush polymer is not used, and Comparative Example 2, in which linear PEG is used, the interfacial impedance on the surface of the lithium metal negative electrode is significantly increased in the case of Example 1, in which the bottle-brush polymer according to the embodiment is added to the electrolyte and used. Therefore, it can be seen that the performance of the lithium metal battery according to the embodiment is excellent.

[0160] Additionally, refer to Figure 13 It can be confirmed that, compared with Comparative Example 1 which does not use the bottle brush polymer, the interfacial impedance on the surface of the lithium metal negative electrode is significantly increased in all cases of Examples 1 to 3 using the bottle brush polymer according to the embodiments.

[0161] Evaluation 4: Electrolyte viscosity The viscosity of the electrolytes prepared in Examples 1 to 3, as well as Comparative Examples 1 and 2, was measured, and the results are shown in... Figure 14 middle.

[0162] Viscosity was measured using an Anton-Paar MCR-302 rheometer at shear rates from 1 / s to 100 / s.

[0163] Figure 14 This is a graph showing the viscosity of the electrolyte according to Example 1 and Comparative Example 1 and Comparative Example 2.

[0164] Reference Figure 14 It can be confirmed that, compared to Comparative Example 1 which does not use a bottle-brush polymer and Comparative Example 2 which uses linear PEG, the viscosity increases when the electrolyte of Example 1 includes the bottle-brush polymer according to the embodiment. Therefore, it can be seen that the lithium metal battery according to the embodiment has excellent performance.

[0165] Evaluation 5: Electrolytes 7 Li NMR analysis The electrolytes prepared in Examples 1 to 3, as well as Comparative Examples 1 and 2, were dissolved in a D2O solution at 25°C and subjected to... 7 Li NMR analysis, and the results are shown in Figure 15 and Figure 16 middle.

[0166] Figure 15 For the electrolytes according to Example 1 and Comparative Example 1 and Comparative Example 2 7 Li NMR analysis diagram. Figure 16 For the electrolytes according to Examples 1 to 3 and Comparative Example 1 7 Li NMR analysis diagram.

[0167] Reference Figure 15 As can be seen, the linear PEG used in Comparative Example 2 exhibits a greater interaction with lithium ions compared to the bottle-brush polymer used in Example 1. This is presumably because the bottle-brush polymer possesses steric effects due to its structure. In other words, linear PEG can freely transform its structure in solution to form a greater interaction with lithium ions, while the bottle-brush polymer, due to steric hindrance between polymers existing as side chains, cannot freely transform and therefore may only partially interact with lithium ions.

[0168] At the same time, refer to Figure 16 As can be seen, the bottle brush polymer used in Example 3 has a greater interaction with lithium ions compared to the bottle brush polymers used in Examples 1 and 2, and this is because the bottle brush polymer used in Example 3 has the largest number of side chains.

[0169] Evaluation 6: Ratio Performance LiFePO4 with a discharge capacity of 160 mAh / g was used as the positive electrode active material to form the positive electrode, lithium metal was used as the negative electrode, and lithium metal batteries were manufactured using the electrolytes prepared in Examples 1 to 3, as well as Comparative Examples 1 and 2. The manufactured lithium metal batteries were subjected to 50 charge / discharge cycles. Specifically, for cycles 1 to 5, charging and discharging were performed at 0.2C; for cycles 6 to 10, charging and discharging were performed at 0.5C; for cycles 11 to 15, charging and discharging were performed at 1C; for cycles 16 to 20, charging and discharging were performed at 2C; and from cycle 21 onwards, charging and discharging were performed at 0.5C. After cycling, the rate performance of the batteries was measured, and the results are shown in... Figure 17 middle.

[0170] Figure 17 A graph illustrating the rate performance of lithium metal batteries according to Examples 1 to 3 and Comparative Examples 1 and 2.

[0171] Reference Figure 17 It can be confirmed that, compared with Comparative Example 1 in which a bottle brush polymer is not used and Comparative Example 2 in which linear PEG is used, the lithium metal battery exhibits superior rate performance in Examples 1 to 3 in which a bottle brush polymer according to the embodiments is added to the electrolyte and used.

[0172] Rating 7: Cyclic Durability The lithium metal battery manufactured in Evaluation 6 was subjected to 120 charge / discharge cycles. Specifically, for the first five cycles, the charge / discharge rate was 0.1C; from the sixth cycle onwards, the charge / discharge rate was 1C. After cycling, the cycle durability of the battery was measured, and the results are shown below. Figure 18 middle.

[0173] Figure 18 A graph illustrating the cycle durability of lithium metal batteries according to Examples 1 to 3 and Comparative Examples 1 and 2.

[0174] Reference Figure 18 It can be confirmed that, compared with Comparative Example 2 which uses linear PEG, the lithium metal batteries exhibit superior cycle durability in the cases of Examples 1 to 3, in which a bottle-brush polymer according to the embodiments is added to the electrolyte and used.

[0175] Evaluation 8: Coulomb efficiency Li / Cu asymmetric lithium metal batteries were fabricated using lithium metal as the negative electrode and the electrolytes prepared in Examples 1 to 3 and Comparative Examples 1 and 2. The coulombic efficiency of the fabricated lithium metal batteries was measured by the following method, and the results are shown in [Table / Figure / Text - 'Li / Cu asymmetric lithium metal batteries']. Figure 19 and Figure 20 middle.

[0176] At 0.5mA / cm 2 Under the condition of 4mAh / cm 2 Lithium metal was electrochemically deposited on the surface of a copper foil and desorbed at 1 V. Subsequently, at 0.5 mA / cm 2 Under the condition of 4mAh / cm 2 The lithium metal was then deposited again on the copper foil. Subsequently, at 0.5 mA / cm²... 2 Under the condition of 1mAh / cm 2 The deposition and desorption of lithium metal were repeated 10 times. Subsequently, all lithium metal was desorbed at 1V.

[0177] Figure 19 A graph showing the voltage change over time of lithium metal batteries according to Examples 1 to 3 and Comparative Examples 1 and 2. Figure 20 A graph showing the coulombic efficiency of lithium metal batteries according to Examples 1 to 3 and Comparative Examples 1 and 2.

[0178] Reference Figure 19 and Figure 20 It can be confirmed that, compared with Comparative Example 2 which uses linear PEG, the lithium metal battery exhibits superior coulombic efficiency in Examples 1 to 3, in which a bottle-brush polymer according to the embodiments is added to the electrolyte and used.

[0179] Evaluation 9: Nucleation overpotential For the lithium metal battery manufactured in Evaluation 8, at 0.5 mA / cm 2 and 0.5mAh / cm 2 Under the conditions of [condition], a charge / discharge cycle was performed, and the nucleation overvoltage during lithium deposition was measured. The results are shown in [figure]. Figure 21 middle.

[0180] Figure 21 A diagram illustrating the nucleation overvoltage of a lithium metal battery according to Example 1 and Comparative Examples 1 and 2.

[0181] Reference Figure 21 It can be confirmed that, compared with Comparative Example 1 in which a bottle-brush polymer was not used and Comparative Example 2 in which linear PEG was used, the nucleation overvoltage is high in Example 1, in which a bottle-brush polymer according to the embodiment is added to the electrolyte and used. Therefore, when Li nuclei are formed in a small size, dense and uniform Li deposition occurs, thereby ensuring stable cycling performance.

[0182] Evaluation 10: Exchange current density The exchange current density of the lithium metal battery manufactured in Evaluation 1 was measured, and the results are shown in... Figure 22 and Figure 23 middle.

[0183] Specifically, linear scan voltammetry (LSV) was performed using a Biologics VSP-300 EIS at a rate of 1 mV / s.

[0184] Figure 22 This is a graph showing the exchange current density of lithium metal batteries according to Example 1 and Comparative Example 1 and Comparative Example 2. Figure 23 It is a graph showing the exchange current density of lithium metal batteries according to Examples 1 to 3 and Comparative Example 1.

[0185] Reference Figure 22As can be seen, compared to Comparative Example 1, in which a bottle-brush polymer is not used, and Comparative Example 2, in which linear PEG is used, the lithium metal battery exhibits a lower exchange current density in Example 1, where the bottle-brush polymer according to the embodiment is added to the electrolyte and used. This demonstrates that, according to the embodiment, lithium ions are uniformly and densely deposited on the surface of the lithium metal negative electrode.

[0186] Additionally, refer to Figure 23 As can be seen, the lithium metal batteries in Examples 1 to 3 using the bottle-brush polymer according to the embodiments have lower exchange current densities compared to the lithium metal battery in Comparative Example 1 which does not use the bottle-brush polymer. Furthermore, when comparing Examples 1 to 3, it can be seen that the exchange current density of the lithium metal battery decreases as the side chain packing density of the bottle-brush polymer decreases. This demonstrates that as the side chain packing density of the bottle-brush polymer decreases, the surface coverage of lithium metal improves due to the more flexible and curved structure of the bottle-brush polymer.

[0187] Evaluation 11: Raman spectroscopy analysis Raman spectroscopy analysis was performed on the electrolytes prepared in Examples 1 to 3 and Comparative Example 1 at 25 °C, and the results are shown in... Figure 24 middle.

[0188] Figure 24 Raman spectra of the electrolytes according to Examples 1 to 3 and Comparative Example 1.

[0189] Reference Figure 24 As can be seen, the bottle-brush polymers used in Examples 1 to 3 cause the Raman shift of the electrolyte to move toward the region of free (or unbound) FSI anions.

[0190] Although embodiments of the present disclosure have been described in detail above, the scope of the present disclosure is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present disclosure as defined in the appended claims also fall within the scope of the present disclosure.

Claims

1. An electrolyte for a lithium metal battery, the electrolyte comprising: Lithium salts; Organic solvents; as well as Bottle-brush-like polymer, comprising repeating units represented by chemical formula 1, The bottle-brush-like polymer has a bottle-brush-like structure comprising side chains in the repeating units connected to a backbone in the repeating units and arranged in an outward direction, with the spacing between the side chains being uniformly arranged. The side chain packing density, defined by the value of x / (x+y) in formula 1, is 1 / 8 to 1. [Chemical Formula 1] In chemical formula 1, Both A1 and A2 are independent skeletons, which are linking groups formed by ring-opening of norbornene or norbornene derivatives, or linking groups derived from acrylates. B is a side chain, which is a substituted or unsubstituted C1 to C20 alkyl group, wherein at least one -CH2- group of the alkyl group is replaced by a substituted or unsubstituted C1 to C20 oxoalkylene group, -O-, -CO-, -CO-O-, -O-CO-, -S-, -Si-, -O-Si-, -ROR-, a linking group derived from a heterocyclic compound, or a linking group derived from bisphenol A, wherein R is a substituted or unsubstituted C1 to C20 haloalkylene group. x is an integer in the range of 1 to 500. y is an integer in the range of 0 to 500. t is an integer in the range of 1 to 500.

2. The electrolyte for lithium metal batteries according to claim 1, wherein, The bottle-brush polymer includes repeating units in which y is 0 to 7 when x is 1 in chemical formula 1.

3. The electrolyte for lithium metal batteries according to claim 1, wherein, The side chain packing density is 1 / 4 to 1.

4. The electrolyte for lithium metal batteries according to claim 1, wherein, The bottle-brush-like polymer has a structure in which adjacent side chains are arranged in different outward directions.

5. The electrolyte for lithium metal batteries according to claim 1, wherein, The bottle-brush-like polymer has a flexible bending structure or a rigid rod-like structure.

6. The electrolyte for lithium metal batteries according to claim 1, wherein, The bottle-brush-like polymer includes at least one of a compound containing a structural unit represented by chemical formula 2, a compound containing a structural unit represented by chemical formula 3, and a compound containing a structural unit represented by chemical formula 4. [Chemical Formula 2] [Chemical Formula 3] [Chemical Formula 4] In chemical formulas 2 to 4 A1, A2, and B are the same as those defined in Chemical Formula 1, and t1 to t3 are all integers in the range of 1 to 500.

7. The electrolyte for lithium metal batteries according to claim 1, wherein, The bottle-brush-like polymer comprises at least one repeating unit represented by chemical formula 5 and repeating units represented by chemical formula 6. [Chemical Formula 5] [Chemical Formula 6] In chemical formulas 5 and 6, R' is a substituted or unsubstituted C1 to C20 alkyl group. Both B1 and B2 are side chains, which are substituted or unsubstituted C1 to C20 alkyl groups, wherein at least one -CH2- group of the alkyl group is replaced by a substituted or unsubstituted C1 to C20 oxoalkylene group, -O-, -CO-, -CO-O-, -O-CO-, -S-, -Si-, -O-Si-, -ROR-, a linking group derived from a heterocyclic compound, or a linking group derived from bisphenol A, wherein R is a substituted or unsubstituted C1 to C20 haloalkylene group. x1 and x2 are both integers in the range of 1 to 500. y1 and y2 are both integers in the range of 0 to 500, and t4 and t5 are both integers in the range of 1 to 500.

8. The electrolyte for lithium metal batteries according to claim 1, wherein, In Formula 1, B includes a substituent derived from at least one compound selected from the group consisting of polyethylene glycol, polypropylene glycol, polycarbonate, polycaprolactone, and perfluoropolyether.

9. The electrolyte for lithium metal batteries according to claim 1, wherein, In chemical formula 1, B includes at least one substituent selected from chemical formulas 7-1 to 7-6. [Chemical Formula 7-1] [Chemical Formula 7-2] [Chemical Formula 7-3] [Chemical Formula 7-4] [Chemical Formula 7-5] [Chemical Formula 7-6] In chemical formulas 7-1 to 7-6 n1 to n13 are all integers in the range of 1 to 20.

10. The electrolyte for lithium metal batteries according to claim 1, wherein, Based on the total amount of the electrolyte, the content of the bottle-brush polymer is from 0.1 wt% to 20 wt%.

11. The electrolyte for lithium metal batteries according to claim 1, wherein, The lithium salt includes at least one of LiSCN, LiN(CN)2, LiClO4, LiBF4, LiAsF6, LiPF6, LiCF3SO3, LiC(CF3SO2)3, LiN(SO2C2F5)2, LiN(SO2CF3)2, LiN(SO2F)2, LiSbF6, LiPF3(CF2CF3)3, LiPF3(CF3)3, and LiB(C2O4)2.

12. The electrolyte for lithium metal batteries according to claim 1, wherein, The organic solvent comprises at least one selected from the group consisting of propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butenyl carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, isopropyl methyl carbonate, dipropyl carbonate, dibutyl carbonate, benzyl nitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, 1,3-dioxolane, 4-methyldioxolane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, and dimethyl ether.

13. The electrolyte for lithium metal batteries according to claim 1, wherein, The electrolyte also includes ionic liquids.

14. The electrolyte for lithium metal batteries according to claim 13, wherein, The ionic liquid comprises at least one selected from the group consisting of: i) at least one cation selected from the group consisting of ammonium, pyrrolidineonium, pyridinium, pyrimidineonium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, strontium, and triazolium; and ii) at least one cation selected from the group consisting of BF4. - PF6 - AsF6 - SbF6 - AlCl4 - HSO4 - ClO4 - CH3SO3 - CF3CO2 - Cl - ,Br - I - F - SO4 - CF3SO3 - (FSO2)2N - (C2F5SO2)2N - (C2F5SO2)(CF3SO2)N - and (CF3SO2)2N - At least one anion selected from the group.

15. A lithium metal battery, the lithium metal battery comprising: Negative electrode, including lithium metal or lithium metal alloy; Positive electrode; as well as The electrolyte according to any one of claims 1 to 14 is disposed between the negative electrode and the positive electrode.

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