Lithium metal battery

Abstract

The present invention relates to a lithium metal battery having improved lifespan and stability, in which the present invention relates to a lithium metal battery comprising: a positive electrode; a lithium metal negative electrode; a separator disposed between the positive electrode and the lithium metal negative electrode; and a non-aqueous electrolyte solution comprising an organic solvent, a lithium salt, and a compound represented by formula I described in the specification.

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2022-0126772, filed on October 5, 2022, the disclosure of which is incorporated herein by reference. Technical Field

[0003] The present invention relates to a lithium metal battery, which comprises a non-aqueous electrolyte containing a silane compound. Background Art

[0004] Recently, there has been a growing interest in energy storage technology, and in electrochemical devices, there has been a growing interest in rechargeable secondary batteries. In particular, lithium secondary batteries, which were developed in the early 1990s, have attracted much attention because they have the advantage of having a higher operating voltage and a significantly higher energy density. Lithium secondary batteries are composed of the following components: a negative electrode, which contains a negative electrode active material such as a carbon material or a silicon material capable of inserting and extracting lithium ions; a positive electrode, which contains a positive electrode active material such as a lithium-containing oxide; and a non-aqueous electrolyte in which a lithium salt is dissolved in an organic solvent.

[0005] Lithium metal batteries are batteries that use lithium metal or lithium alloys as the negative electrode in lithium secondary batteries. Lithium has a high specific capacity of about 3,860 mAh / g, a very low standard redox potential (-3.04 V relative to SHE), and a low density (0.534 g / cm 3 ), so it is considered to be the most suitable material to replace the negative electrode containing negative electrode active materials such as carbon materials or silicon materials.

[0006] For lithium metal batteries, a solid electrolyte interface (SEI) layer composed of decomposition products formed by a chemical reaction with an electrolyte is formed on the surface of a lithium metal negative electrode, wherein lithium dendrites are formed while lithium grows into a dendrite (tree-like form) because of the additional local electrodeposition of lithium, resulting in a problem of internal short circuit of the battery. In addition, because the uneven electrodeposition of lithium may produce dead lithium (dead lithium) to damage the previously formed SEI layer, the surface of the lithium metal negative electrode may be exposed to cause chain decomposition of the electrolyte, resulting in problems of deterioration of the capacity, stability, and life performance of the battery and increase in battery resistance. Summary of the invention

[0007] Technical issues

[0008] One aspect of the present invention provides a lithium metal battery having improved lifespan characteristics.

[0009] Technical Solution

[0010] (1) The present invention provides a lithium metal battery, the lithium metal battery comprising:

[0011] positive electrode;

[0012] Lithium metal anode;

[0013] a separator disposed between the positive electrode and the lithium metal negative electrode; and

[0014] A non-aqueous electrolyte comprising an organic solvent, a lithium salt and a compound represented by Formula I.

[0015] [Formula I]

[0016]

[0017] In Formula I,

[0018] R a is a C1-C 10 alkyl,

[0019] R b Each independently is unsubstituted or substituted with at least one fluorine element C1-C 10 alkyl,

[0020] R' is independently hydrogen; unsubstituted or substituted C1-C 10 Alkyl; or unsubstituted or substituted C1-C 10 heteroalkyl, and

[0021] R'' is unsubstituted or substituted C2-C 10 Alkenyl; or unsubstituted or substituted C2-C 10 Alkynyl.

[0022] (2) The present invention provides the lithium metal battery described in (1) above, wherein the non-aqueous electrolyte further comprises at least one compound selected from the group consisting of compounds represented by Formula II to Formula V.

[0023] [Formula II]

[0024]

[0025] [Formula III]

[0026]

[0027] [Formula IV]

[0028] Si(R'')4

[0029] [Formula V]

[0030]

[0031] In Formula II to Formula V,

[0032] R b Each independently is unsubstituted or substituted with at least one fluorine element C1-C 10 alkyl,

[0033] R c are each independently unsubstituted or substituted C1-C 10 alkyl,

[0034] R' is independently hydrogen; unsubstituted or substituted C1-C 10 Alkyl; or unsubstituted or substituted C1-C 10 Heteroalkyl,

[0035] R'' is unsubstituted or substituted C2-C 10 Alkenyl; or unsubstituted or substituted C2-C 10 Alkynyl,

[0036] R d and R e are each independently hydrogen; unsubstituted or substituted C1-C 10 Alkyl; unsubstituted or substituted C1-C 10 heteroalkyl; or unsubstituted or substituted siloxane,

[0037] Among them, in R d and R e When all of them are siloxane groups, R d and R e may be connected to each other to form a ring consisting of siloxane bonds, and

[0038] n is 2 or 3.

[0039] (3) The present invention provides the lithium metal battery described in (2) above, wherein the compound represented by Formula I is at least one compound selected from the compounds of Formulas Ia to If.

[0040] [Formula Ia]

[0041]

[0042] [Formula Ib]

[0043]

[0044] [Formula Ic]

[0045]

[0046] [FormulaId]

[0047]

[0048] [Formula Ie]

[0049]

[0050] [Formula If]

[0051]

[0052] (4) The present invention provides the lithium metal battery described in (2) or (3) above, wherein the compound represented by formula II is at least one compound selected from the compounds of formula II-a to formula II-f.

[0053] [Formula II-a]

[0054]

[0055] [Formula II-b]

[0056]

[0057] [Formula II-c]

[0058]

[0059] [Formula II-d]

[0060]

[0061] [Formula II-e]

[0062]

[0063] [Formula II-f]

[0064]

[0065] (5) The present invention provides the lithium metal battery described in any one of (2) to (4) above, wherein the compound represented by Formula III is at least one compound selected from the group consisting of compounds of Formula III-a to Formula III-o.

[0066] [Formula III-a]

[0067]

[0068] [Formula III-b]

[0069]

[0070] [Formula III-c]

[0071]

[0072] [Formula III-d]

[0073]

[0074] [Formula III-e]

[0075]

[0076] [Formula III-f]

[0077]

[0078] [Formula III-g]

[0079]

[0080] [Formula III-h]

[0081]

[0082] [Formula III-i]

[0083]

[0084] [Formula III-j]

[0085]

[0086] [Formula III-k]

[0087]

[0088] [Formula III-1]

[0089]

[0090] [Formula III-m]

[0091]

[0092] [Formula III-n]

[0093]

[0094] [Formula III-o]

[0095]

[0096] (6) The present invention provides the lithium metal battery described in any one of (2) to (5) above, wherein the compound represented by Formula IV is at least one compound selected from the group consisting of compounds of Formula IV-a to Formula IV-c.

[0097] [Formula IV-a]

[0098]

[0099] [Formula IV-b]

[0100]

[0101] [Formula IV-c]

[0102]

[0103] (7) The present invention provides the lithium metal battery described in any one of (2) to (6) above, wherein the compound represented by Formula V is at least one compound selected from the group consisting of compounds of Formula Va and Formula Vb.

[0104] [Formula Va]

[0105]

[0106] [Formula Vb]

[0107]

[0108] Beneficial Effects

[0109] In the case where the compound represented by formula I is included as a silane compound in the non-aqueous electrolyte as in the present invention, a lithium metal battery with excellent stability and life characteristics can be provided because a solid electrolyte interface (SEI) layer with high structural flexibility and stability is formed on the lithium metal negative electrode through chemical reactions including electrochemical reactions and a physical force (adhesion force) is also generated between the SEI layer and the lithium metal negative electrode. DETAILED DESCRIPTION

[0110] Hereinafter, the present invention will be described in more detail.

[0111] It should be understood that the words or terms used in the specification and claims should not be interpreted as the meanings defined in commonly used dictionaries. It should also be understood that the words or terms should be interpreted as having meanings consistent with their background and technical ideas in the relevant fields of the present invention, based on the inventor's ability to appropriately define the meanings of the words or terms to best explain the principles of the present invention.

[0112] The terms used herein are only used to describe specific embodiments and are not intended to limit the present invention. In the specification, unless otherwise specified, the terms in the singular may include the plural form. In the present invention, it should also be understood that when the term "comprising" or "having" is used in this specification, the existence of the feature, number, step, element or its combination is specified, but the existence or addition of one or more other features, numbers, steps, elements or its combination is not excluded.

[0113] The present invention provides a lithium metal battery, the lithium metal battery comprising:

[0114] positive electrode;

[0115] Lithium metal anode;

[0116] a separator disposed between the positive electrode and the lithium metal negative electrode; and

[0117] A non-aqueous electrolyte comprising an organic solvent, a lithium salt and a compound represented by Formula I.

[0118] [Formula I]

[0119]

[0120] In Formula I,

[0121] R a is a C1-C 10 alkyl,

[0122] R b Each independently is unsubstituted or substituted with at least one fluorine element C1-C 10 alkyl,

[0123] R' is independently hydrogen; unsubstituted or substituted C1-C 10 Alkyl; or unsubstituted or substituted C1-C 10 heteroalkyl, and

[0124] R'' is unsubstituted or substituted C2-C 10 Alkenyl; or unsubstituted or substituted C2-C 10 Alkynyl.

[0125] In the present invention, with respect to the substituted alkyl, substituted heteroalkyl, substituted alkenyl, substituted alkynyl or substituted siloxane group, the substituent may be deuterium (-D), a hydroxyl group (-OH), an amino group (-NR2), a halogen group (-X), a thiol group (-SR), a cyano group (-CN), a carbonyl group (-C(=O)-H, -C(=O)-R, -C(=O)-OH, -C(=O)-NR2, -C(=O)-OR, -C(=O)-X), a carbamate group (-OC(=O)-NR2, -NR-C(=O)OR), a urea group (-N(R)-C(=O)-NR2), a carbonate group (-OC(=O)-OR), an anhydride group (-C(=O)-OC(=O)-R), an ester group (-OC(=O)- )-R), cyanate group (-OCN), isocyanate group (-NCO), thiocyanate group (-SCN), nitrate group (-ON(=O)-OR), sulfonyl group (-S(=O)2-R), sulfinyl group (-S(=O)-R), phosphite group (-OP(OR)2), phosphate group (-OPO(OR)2), phosphinate group (-PO(OR)R), phosphite group (-P(OR)R2), phosphonate group (-PO3R2), phosphite group (-P(OR)2), boric acid (-B(OR)2), borate (-OB(OR)2), borane (-BR2), siloxane group (-Si-O-Si-R), silane group (-SiR4) or linear or branched C1-C6 alkoxy group. In this case, in the above substituents, X is a halogen group, and R can be each independently a C1-C6 alkoxy group. 10 Alkyl; C2-C 10 Alkenyl; or C2-C 10 Alkynyl.

[0126] The inventors of the present invention have found that in the case where the compound represented by Formula I is included in the non-aqueous electrolyte of a lithium metal battery, because the hydroxyl groups on the surface of the negative electrode or the positive electrode (the hydroxyl groups of LiOH present on the surface of the lithium metal negative electrode; for the positive electrode, the hydroxyl groups present on the surface of the positive electrode active material (e.g., lithium metal oxide)) form a covalent bond ([electrode] -O-Si-O-) with the compound represented by Formula I, a solid electrolyte interface (SEI) layer that is not significantly affected by volume changes, i.e., excellent in mechanical rigidity, is formed. Specifically, the inventors of the present invention have found that in the case where the negative electrode is a lithium metal negative electrode, because a Li-Si-O network is formed between the negative electrode and the additive and an -O-Si-O-Si-O- network is formed between the SEI layer and the additive, the lithium metal negative electrode that has stability problems due to the formation of lithium dendrites during charge and discharge can be protected.

[0127] Because the Li-Si-O network between the negative electrode and the additive has the function of promoting Li +The effect of the movement at the interface between the negative electrode and the electrolyte can prevent an increase in the resistance in the battery, and even when the battery is rapidly charged, the battery performance can be maintained without degradation.

[0128] In addition, since the compound represented by Formula I contains a fluorine element, it becomes a source of fluoride anions during the reduction / oxidation decomposition reaction, thereby contributing to the formation of the stable inorganic compound LiF contained in the SEI layer. Further, since the compound represented by Formula I contains an unsubstituted or substituted alkenyl group or an unsubstituted or substituted alkynyl group, it can form a polymer-form SEI layer by forming C-C bonds through the reduction / oxidation decomposition reaction.

[0129] As a result, although the battery according to the present invention is a lithium metal battery, it is characterized in that, because an SEI layer with high structural flexibility and stability is formed, it has excellent high-temperature stability and life characteristics.

[0130] (1) Positive electrode

[0131] The positive electrode can be prepared by coating a positive electrode current collector with a positive electrode paste containing a positive electrode active material, a binder, a conductive material, and a solvent.

[0132] The positive electrode current collector is not particularly limited as long as it has conductivity and does not cause an adverse chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, fired carbon; or aluminum or stainless steel surface-treated with one of carbon, nickel, titanium, silver, etc. can be used. Further, fine irregularities can be formed on its surface to improve the bonding strength with the positive electrode active material, and the positive electrode current collector can be used in various shapes such as a film, a sheet, a foil, a net, a porous body, a foam body, a non-woven fabric body, etc.

[0133] The positive electrode active material is a compound capable of reversibly intercalating and deintercalating lithium, and specifically, the positive electrode active material can include a lithium metal oxide containing lithium and at least one metal such as cobalt, manganese, nickel, or aluminum. More specifically, the lithium metal oxide can include: lithium-manganese-based oxides (such as LiMnO2, LiMn2O4, etc.), lithium-cobalt-based oxides (such as LiCoO2, etc.), lithium-nickel-based oxides (such as LiNiO2, etc.), lithium-nickel-manganese-based oxides (such as LiNi 1-Y Mn Y O2 (where 0 < Y < 1), LiMn 2-Z Ni Z O4 (where 0 < Z < 2), etc.), lithium-nickel-cobalt-based oxides (such as LiNi 1-Y1 Co Y1 O2 (where 0 < Y1 < 1), etc.), lithium-manganese-cobalt-based oxides (such as LiCo 1-Y2 Mn Y2O2 (where 0 < Y2 < 1), LiMn 2-Z1 Co Z1 O4 (where 0 < Z1 < 2), etc., lithium-nickel-manganese-cobalt oxides (such as Li(Ni p Co q Mn r1 )O2 (where 0 < p < 1, 0 < q < 1, 0 < r1 < 1 and p + q + r1 = 1) or Li(Ni p1 Co q1 Mn r2 )O4 (where 0 < p1 < 2, 0 < q1 < 2, 0 < r2 < 2 and p1 + q1 + r2 = 2), etc., or lithium-nickel-cobalt-transition metal (M) oxides (such as Li(Ni p2 Co q2 Mn r3 M s2 )O2 (where M is selected from: aluminum (Al), iron (Fe), vanadium (V), chromium (Cr), titanium (Ti), tantalum (Ta), magnesium (Mg) and molybdenum (Mo), and p2, q2, r3 and s2 are the atomic fractions of the respective independent elements, where 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1 and p2 + q2 + r3 + s2 = 1), etc.), and may include any one of them or a mixture of two or more of them.

[0134] Among these materials, in terms of improving the capacity characteristics and stability of the battery, the lithium metal oxide can be LiCoO2, LiMnO2, LiNiO2, lithium nickel manganese cobalt oxides (such as Li(Ni 1 / 3 Mn 1 / 3 Co 1 / 3 )O2, Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni 0.5 Mn 0.3 Co 0.2 )O2, Li(Ni 0.7 Mn 0.15 Co 0.15 )O2 and Li(Ni 0.8 Mn 0.1 Co 0.1 )O2, etc.) or lithium nickel cobalt aluminum oxides (such as LiNi 0.8 Co 0.15 Al 0.05 O2, etc.), and considering the significant improvement effect brought about by controlling the type and content ratio of the components constituting the lithium composite metal oxide, the lithium composite metal oxide can be Li(Ni 0.6 Mn 0.2 Co 0.2)O2、Li(Ni 0.5 Mn 0.3 Co 0.2 )O2、Li(Ni 0.7 Mn 0.15 Co 0.15 )O2 and Li(Ni 0.8 Mn 0.1 Co 0.1 )O2, and any one of them or a mixture of two or more thereof can be used.

[0135] The positive electrode active material may be contained in an amount of 60 to 99 wt %, preferably 70 to 99 wt %, and more preferably 80 to 98 wt %, based on the total weight of solids excluding the solvent in the positive electrode slurry.

[0136] The binder is a component that facilitates bonding between the active material and the conductive material and bonding with the current collector.

[0137] Examples of the binder may be polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene (PE), polypropylene, EPDM rubber, sulfonated EPDM rubber, styrene-butadiene rubber, fluororubber, or various copolymers.

[0138] The content of the binder may generally be 1 to 20 wt %, preferably 1 to 15 wt %, and more preferably 1 to 10 wt %, based on the total weight of solids excluding the solvent in the positive electrode slurry.

[0139] The conductive material is a component for further improving the conductivity of the positive electrode active material.

[0140] The conductive material is not particularly limited as long as it has conductivity and does not cause adverse chemical changes in the battery, and for example, conductive materials such as graphite; carbon materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black or thermal black; conductive fibers such as carbon fibers or metal fibers; fluorocarbons; metal powders such as aluminum powder and nickel powder; conductive whiskers such as zinc oxide whiskers and potassium titanate whiskers; conductive metal oxides such as titanium oxide; or polyphenylene derivatives can be used.

[0141] Based on the total weight of solids excluding the solvent in the positive electrode slurry, the content of the conductive material may generally be 1 wt % to 20 wt %, preferably 1 wt % to 15 wt %, and more preferably 1 wt % to 10 wt %.

[0142] The solvent may include an organic solvent such as N-methyl-2-pyrrolidone (NMP), and may be used in an amount such that a desired viscosity is obtained when the positive electrode active material and optional binder and conductive material are included. For example, the solvent may be included in an amount such that the concentration of the solids containing the positive electrode active material and optional binder and conductive material is in the range of 50% by weight to 95% by weight, preferably 70% by weight to 95% by weight, and more preferably 70% by weight to 90% by weight.

[0143] (2) Lithium metal anode

[0144] The negative electrode is a lithium metal negative electrode, wherein the negative electrode can be a lithium thin film itself or can be prepared by physically combining, extruding, rolling or depositing lithium on a negative electrode current collector. As a deposition method, an electrodeposition method or a chemical vapor deposition method of a metal can be used.

[0145] In the case where the negative electrode is prepared by physically combining, rolling or depositing lithium on the negative electrode collector, the thickness of the negative electrode collector is generally 3 μm to 500 μm. The negative electrode collector is not particularly limited as long as it has high conductivity and does not cause adverse chemical changes in the battery, and for example: copper, stainless steel, aluminum, nickel, titanium, fired carbon; copper or stainless steel surface-treated with one of carbon, nickel, titanium, silver, etc.; aluminum-cadmium alloy, etc. In addition, similar to the positive electrode collector, the negative electrode collector may have fine surface irregularities to improve the bonding strength, and the negative electrode collector may be used in various shapes such as films, sheets, foils, nets, porous bodies, foams, non-woven fabrics, etc.

[0146] (3) Diaphragm

[0147] In addition, as a separator, a conventional porous polymer film commonly used as a separator, for example, a porous polymer film prepared from a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer can be used alone or in a laminated form, and a typical porous non-woven fabric, for example, a non-woven fabric formed of a high melting point glass fiber or a polyethylene terephthalate fiber can be used, but the present invention is not limited thereto. In addition, a coated separator containing a ceramic component or a polymer material can be used to ensure heat resistance or mechanical strength, and a separator having a single-layer or multi-layer structure can be optionally used.

[0148] (4) Non-aqueous electrolyte

[0149] The nonaqueous electrolyte according to the present invention includes an organic solvent, a lithium salt and a compound represented by Formula I.

[0150] [Formula I]

[0151]

[0152] In Formula I,

[0153] R a is a C1-C 10 alkyl,

[0154] R b are each independently unsubstituted or substituted with at least one fluorine element. 10 alkyl,

[0155] R' is independently hydrogen; unsubstituted or substituted C1-C 10 Alkyl; or unsubstituted or substituted C1-C 10 heteroalkyl, and

[0156] R'' is unsubstituted or substituted C2-C 10 Alkenyl; or unsubstituted or substituted C2-C 10 Alkynyl.

[0157] According to the present invention, the non-aqueous electrolyte may further include at least one compound selected from the group consisting of compounds represented by Formula II to Formula V.

[0158] [Formula II]

[0159]

[0160] [Formula III]

[0161]

[0162] [Formula IV]

[0163] Si(R'')4

[0164] [Formula V]

[0165]

[0166] In Formula II to Formula V,

[0167] R b Each independently is unsubstituted or substituted with at least one fluorine element C1-C 10 alkyl,

[0168] R c are each independently unsubstituted or substituted C1-C 10 alkyl,

[0169] R' is independently hydrogen; unsubstituted or substituted C1-C 10 Alkyl; or unsubstituted or substituted C1-C 10 Heteroalkyl,

[0170] R'' is unsubstituted or substituted C2-C 10 Alkenyl; or unsubstituted or substituted C2-C 10 Alkynyl,

[0171] R d and R e are each independently hydrogen; unsubstituted or substituted C1-C 10 Alkyl; unsubstituted or substituted C1-C 10 heteroalkyl; or unsubstituted or substituted siloxane,

[0172] Among them, d and R e When all of them are siloxane groups, R d and R e may be connected to each other to form a ring consisting of siloxane bonds, and

[0173] n is 2 or 3.

[0174] The non-aqueous electrolyte according to the present invention may contain a compound represented by Formula I and at least one selected from the compounds represented by Formula II to Formula V. That is, the non-aqueous electrolyte according to the present invention contains compounds represented by Formula I and Formula II at the same time, compounds represented by Formula I and Formula III at the same time, compounds represented by Formula I and Formula IV at the same time, compounds represented by Formula I and Formula V at the same time, compounds represented by Formula I, Formula II and Formula III at the same time, compounds represented by Formula I, Formula II and Formula IV at the same time, compounds represented by Formula I, Formula II and Formula V at the same time, compounds represented by Formula I, Formula III and Formula IV at the same time, compounds represented by Formula I, Formula III and Formula V at the same time, compounds represented by Formula I to Formula IV at the same time, compounds represented by Formula I, Formula II, Formula III and Formula V at the same time, compounds represented by Formula I, Formula II, Formula IV and Formula V at the same time, or compounds represented by Formula I, Formula III, Formula IV and Formula V at the same time.

[0175] In the case where the non-aqueous electrolyte contains at least one of the compound represented by Formula I and the compounds represented by Formulas II to V, a lithium secondary battery having excellent high temperature stability and life characteristics can be provided because a thin and stable SEI layer is formed. In particular, in the case of using a lithium metal negative electrode as a negative electrode of a lithium secondary battery, a thin and stable SEI layer containing not only a siloxane bond but also a carbon-carbon bond is formed, so the high temperature stability and life characteristics of the battery can be further improved.

[0176] 1) A compound represented by formula I

[0177] The compound represented by Formula I can form a SEI layer with excellent mechanical rigidity by forming a covalent bond ([electrode] -O-Si-O-) with a hydroxyl group on the surface of the negative electrode or the positive electrode (a hydroxyl group of LiOH present on the surface of a lithium metal negative electrode; for a positive electrode, a hydroxyl group present on the surface of a positive electrode active material (e.g., a lithium metal oxide)). Specifically, in the case where the negative electrode is a lithium metal negative electrode, because a Li-Si-O network is formed between the negative electrode and the additive and an -O-Si-O-Si-O-network is formed between the SEI layer and the additive, the lithium metal negative electrode that has stability problems due to the formation of lithium dendrites during charge and discharge can be protected. Because the Li-Si-O network between the negative electrode and the additive has the function of promoting Li + Since the negative electrode and the electrolyte have a moving effect at the interface, an increase in resistance in the battery can be prevented, and the battery performance may not be reduced even when the battery is quickly charged.

[0178] In addition, since the compound represented by Formula I contains fluorine element, it becomes a source of fluorine anions during the reduction / oxidation decomposition reaction, thereby contributing to the formation of the stable inorganic compound LiF contained in the SEI layer. In addition, since the compound represented by Formula I contains an unsubstituted or substituted alkenyl group or an unsubstituted or substituted alkynyl group, it can form a polymer-formed SEI layer by forming a CC bond through a reduction / oxidation decomposition reaction.

[0179] As a result, although the battery according to the present invention is a lithium metal battery, it is characterized in that high-temperature stability and life characteristics are excellent because an SEI layer having high structural flexibility and stability is formed.

[0180] In Formula I, R a Specifically, it may be a C1-C6 alkyl group substituted with at least one fluorine element, and more specifically, a C1-C5 alkyl group substituted with at least one fluorine element. In this case, since a larger amount of fluorine atoms can be supplied, a more stable SEI layer of the LiF component can be expected to be formed.

[0181] In Formula I, R b Specifically, each of them can be independently C1-C 10 Alkyl, more specifically C1-C6 alkyl substituted by at least one fluorine element, more specifically each independently can be C1-C5 alkyl substituted by at least one fluorine element. In this case, because it becomes a source of fluoride anions during the reduction / oxidation decomposition reaction, a stable LiF-based SEI layer can be formed. Therefore, in a lithium metal battery using a non-aqueous electrolyte containing a compound represented by Formula I, the life of the electrode is improved, and the battery expansion caused by electrolyte decomposition at high temperature can be effectively reduced.

[0182] In Formula I, R' can be specifically each independently hydrogen; or unsubstituted or substituted C1-C 10 The alkyl group is more specifically hydrogen or a substituted C1-C6 alkyl group, and more specifically each independently is hydrogen or a substituted C1-C5 alkyl group. In this case, the substituent group is specifically a fluoro group.

[0183] In Formula I, R'' can specifically be an unsubstituted C2-C 10 Alkenyl or unsubstituted C2-C 10 The alkynyl group, more specifically an unsubstituted C2-C6 alkenyl group or an unsubstituted C2-C6 alkynyl group, more specifically an unsubstituted C2-C5 alkenyl group or an unsubstituted C2-C5 alkynyl group. In this case, the unsaturated carbon bond can form a polymer-formed SEI layer through a reduction / oxidation decomposition reaction at the interface between the two electrodes.

[0184] According to the present invention, the compound represented by Formula I may be at least one compound selected from the group consisting of compounds of the following Formulae Ia to If.

[0185] [Formula Ia]

[0186]

[0187] [Formula Ib]

[0188]

[0189] [Formula Ic]

[0190]

[0191] [FormulaId]

[0192]

[0193] [Formula Ie]

[0194]

[0195] [Formula If]

[0196]

[0197] According to the present invention, based on 100 parts by weight of the non-aqueous electrolyte, the non-aqueous electrolyte may contain 0.01 to 10 parts by weight, specifically 0.01 to 5 parts by weight, 0.01 to 1 part by weight, or 0.1 to 1 part by weight of the compound represented by Formula I. In the case where the amount of the compound represented by Formula I is within the above range, when the non-aqueous electrolyte is used in a lithium metal battery, because the SEI layer derived from the compound represented by Formula I has an appropriate thickness to facilitate the movement of lithium ions and has high mechanical rigidity, stability can be improved and a decrease in battery capacity can be prevented by preventing an increase in the internal resistance of the lithium metal battery.

[0198] The compound represented by formula I can be prepared by a reaction of replacing the halogen element in a silane compound containing silicon (Si) directly bonded to a halogen element with an alcohol, but the present invention is not limited thereto, and the compound represented by formula I can be prepared by a known method. For example, as described in Organometallics, 2011, Vol. 30. #2, pp. 352-355, the compound represented by formula I can also be prepared by a method of introducing an alkyne into a silane compound represented by SiH (OR) 3 in the presence of a transition metal catalyst.

[0199] 2) Compound represented by formula II

[0200] Since the compound represented by Formula II contains two or more unsubstituted or substituted alkenyl groups or unsubstituted or substituted alkynyl groups, it can effectively help form the SEI layer as a crosslinking agent, and as a result, a more solid SEI layer can be formed. By forming such a stable SEI layer, it plays a role in extending the electrode life or effectively reducing the battery expansion caused by electrolyte decomposition.

[0201] In addition, since the compound represented by Formula II becomes a source of fluorine anions during a reduction / oxidation decomposition reaction by including a fluorine element, it plays a role in assisting the formation of a stable inorganic compound LiF included in the SEI layer.

[0202] According to the present invention, in formula II, R b Specifically, each of them can be independently C1-C 10 Alkyl, more specifically C1-C6 alkyl substituted by at least one fluorine element, more specifically each independently can be C1-C5 alkyl substituted by at least one fluorine element. b It may be a C1-C5 alkyl group containing a trifluoro group.

[0203] According to the present invention, in Formula II, R' can be independently hydrogen or unsubstituted C1-C 10The alkyl group is more specifically hydrogen or an unsubstituted C1-C6 alkyl group, and more specifically each independently is hydrogen or an unsubstituted C1-C5 alkyl group.

[0204] According to the present invention, in Formula II, R'' can specifically be an unsubstituted C2-C 10 Alkenyl or unsubstituted C2-C 10 Alkynyl, more specifically unsubstituted C2-C6 alkenyl or unsubstituted C2-C6 alkynyl, more specifically unsubstituted C2-C5 alkenyl or unsubstituted C2-C5 alkynyl.

[0205] According to the present invention, the compound represented by Formula II may be at least one compound selected from the following compounds of Formula II-a to Formula II-f.

[0206] [Formula II-a]

[0207]

[0208] [Formula II-b]

[0209]

[0210] [Formula II-c]

[0211]

[0212] [Formula II-d]

[0213]

[0214] [Formula II-e]

[0215]

[0216] [Formula II-f]

[0217]

[0218] 3) Compound represented by formula III

[0219] Since the compound represented by Formula III contains two or more unsubstituted or substituted alkenyl groups or unsubstituted or substituted alkynyl groups, it can effectively help form the SEI layer as a crosslinking agent, and as a result, a stronger SEI layer can be formed. By forming such a stable SEI layer, it plays a role in extending the electrode life or effectively reducing the battery expansion caused by electrolyte decomposition.

[0220] According to the present invention, in formula III, R c Specifically, they can be independently unsubstituted C1-C 10 Alkyl; C1-C substituted with at least one fluorine element10 Alkyl; or C1-C 10 More specifically, R c may be independently an unsubstituted C1-C6 alkyl group; a C1-C6 alkyl group substituted with at least one fluorine element; 10 or a C1-C6 alkyl substituted by a cyano group.

[0221] According to the present invention, in Formula III, R'' can specifically be an unsubstituted C2-C 10 Alkenyl or unsubstituted C2-C 10 Alkynyl, more specifically unsubstituted C2-C6 alkenyl or unsubstituted C2-C6 alkynyl, more specifically unsubstituted C2-C5 alkenyl or unsubstituted C2-C5 alkynyl.

[0222] According to the present invention, the compound represented by Formula III may be at least one compound selected from the group consisting of the following compounds of Formula III-a to Formula III-o.

[0223] [Formula III-a]

[0224]

[0225] [Formula III-b]

[0226]

[0227] [Formula III-c]

[0228]

[0229] [Formula III-d]

[0230]

[0231] [Formula III-e]

[0232]

[0233] [Formula III-f]

[0234]

[0235] [Formula III-g]

[0236]

[0237] [Formula III-h]

[0238]

[0239] [Formula III-i]

[0240]

[0241] [Formula III-j]

[0242]

[0243] [Formula III-k]

[0244]

[0245] [Formula III-1]

[0246]

[0247] [Formula III-m]

[0248]

[0249] [Formula III-n]

[0250]

[0251] [Formula III-o]

[0252]

[0253] 4) Compound represented by formula IV

[0254] Since the compound represented by Formula IV contains two or more unsubstituted or substituted alkenyl groups or unsubstituted or substituted alkynyl groups, it can effectively help form the SEI layer as a crosslinking agent, and as a result, a stronger SEI layer can be formed. By forming such a stable SEI layer, it plays a role in extending the electrode life or effectively reducing the battery expansion caused by electrolyte decomposition.

[0255] According to the present invention, in Formula IV, R'' can specifically be an unsubstituted C2-C 10 Alkenyl or unsubstituted C2-C 10 Alkynyl, more specifically unsubstituted C2-C6 alkenyl or unsubstituted C2-C6 alkynyl, more specifically unsubstituted C2-C5 alkenyl or unsubstituted C2-C5 alkynyl.

[0256] According to the present invention, the compound represented by Formula IV may be at least one compound selected from the group consisting of compounds of the following Formulae IV-a to IV-c.

[0257] [Formula IV-a]

[0258]

[0259] [Formula IV-b]

[0260]

[0261] [Formula IV-c]

[0262]

[0263] 5) Compound represented by formula V

[0264] Since the compound represented by Formula V contains two or more unsubstituted or substituted alkenyl groups or unsubstituted or substituted alkynyl groups, it can effectively help form the SEI layer as a crosslinking agent, and as a result, a stronger SEI layer can be formed. By forming such a stable SEI layer, it plays a role in extending the electrode life or effectively reducing the battery expansion caused by electrolyte decomposition.

[0265] According to the present invention, in Formula V, R' can be independently hydrogen or unsubstituted C1-C 10 The alkyl group is more specifically hydrogen or an unsubstituted C1-C6 alkyl group, and more specifically each independently is hydrogen or an unsubstituted C1-C5 alkyl group.

[0266] According to the present invention, in Formula V, R'' can specifically be an unsubstituted C2-C 10 Alkenyl or unsubstituted C2-C 10 Alkynyl, more specifically unsubstituted C2-C6 alkenyl or unsubstituted C2-C6 alkynyl, more specifically unsubstituted C2-C5 alkenyl or unsubstituted C2-C5 alkynyl.

[0267] According to the present invention, in Formula V, R d and R e can be specifically each independently hydrogen; unsubstituted C1-C 10 Alkyl; siloxane and / or siloxane substituted by silane; or unsubstituted siloxane, more specifically hydrogen; unsubstituted C1-C6 alkyl; siloxane and / or siloxane substituted by silane; or unsubstituted siloxane, more specifically hydrogen; unsubstituted C1-C5 alkyl; siloxane and / or siloxane substituted by silane; or unsubstituted siloxane. d and R e When all of them are siloxane groups, R d and R e They may be connected to each other to form a ring composed of a siloxane bond.

[0268] According to the present invention, the compound represented by Formula V may be at least one compound selected from the group consisting of compounds of the following Formulae Va and Vb.

[0269] [Formula Va]

[0270]

[0271] [Formula Vb]

[0272]

[0273] When the compound represented by Formula I and at least one compound selected from Formula II to Formula V are simultaneously contained in the non-aqueous electrolyte, the weight ratio (A:B) of the compound represented by Formula I (A) to at least one compound selected from Formula II to Formula V (B) may be in the range of 1:1 to 100:1, particularly 1:1 to 50:1, 1:1 to 40:1, 1:1 to 30:1, 1:1 to 20:1 or 1:1 to 10:1, more particularly 1:1 to 9:1, 1:1 to 8:1, 1:1 to 7:1, 1:1 to 6:1, 1:1 to 5:1, 1:1 to 4:1, 1:1 to 3:1 or 1:1 to 2:1. In this case, since the content of the compound represented by Formula I is greater than that of the compound represented by Formula II to Formula V used as a crosslinking agent, crosslinking can be effectively formed, and thus, a SEI layer with high mechanical rigidity can be formed to improve battery stability. In this case, the non-aqueous electrolyte may include 0.01 to 10 parts by weight, specifically 0.01 to 5 parts by weight, 0.01 to 1 part by weight, or 0.1 to 1 part by weight of the compound represented by Formula I, based on 100 parts by weight of the non-aqueous electrolyte. In addition, the non-aqueous electrolyte may include at least one selected from the compounds represented by Formula II to Formula V in an amount of 0.01 to 10 parts by weight, specifically 0.01 to 5 parts by weight, 0.01 to 2.5 parts by weight, or 0.1 to 0.5 parts by weight, based on 100 parts by weight of the non-aqueous electrolyte. In this case, when the non-aqueous electrolyte is used in a lithium metal battery, because the SEI layer derived from the compound represented by Formula I and at least one selected from the compounds represented by Formula II to Formula V has an appropriate thickness to facilitate the movement of lithium ions and has high mechanical rigidity, stability can be improved and the battery capacity can be prevented from decreasing by preventing an increase in the internal resistance of the lithium metal battery.

[0274] 6) Organic solvents

[0275] The organic solvent is a non-aqueous solvent commonly used in lithium metal batteries, and there is no limitation on the organic solvent as long as it can minimize decomposition caused by oxidation reaction during charge and discharge of the lithium metal battery and can exhibit desired performance together with the compound represented by Formulas I to V.

[0276] The organic solvent can be, for example, a linear carbonate or a cyclic carbonate, a linear ester or a cyclic ester, an ether, a glycol dimethyl ether or a nitrile (acetonitrile, SN, etc.), but is not limited thereto. As the organic solvent, a carbonate electrolyte solvent containing a carbonate compound such as a cyclic carbonate, a linear carbonate or a mixture thereof can be used generally.

[0277] Specific examples of the cyclic carbonate compound are ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, vinylene carbonate, and fluoroethylene carbonate (FEC), but the cyclic carbonate compound is not limited thereto.

[0278] Specific examples of the linear carbonate compound are dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methylpropyl carbonate, and ethylpropyl carbonate, but the linear carbonate compound is not limited thereto.

[0279] Specific examples of the linear ester compound are methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate, but the linear ester compound is not limited thereto.

[0280] Specific examples of the cyclic ester compound are γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone, but the cyclic ester compound is not limited thereto.

[0281] Specific examples of the ether solvent are dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, 1,3-dioxolane (DOL), and 2,2-bis(trifluoromethyl)-1,3-dioxolane (TFDOL), but the ether solvent is not limited thereto.

[0282] Glyme solvents are solvents having a higher dielectric constant and a lower surface tension than linear carbonate organic solvents and having a lower reactivity with metals, wherein the glyme solvents are dimethoxyethane (glyme dimethyl ether, DME), diethoxyethane, diglyme, triglyme and tetraglyme (TEGDME), but are not limited thereto.

[0283] Specific examples of the nitrile solvent are acetonitrile, propionitrile, butyronitrile, valeronitrile, octanonitrile, heptanenitrile, cyclopentanenitrile, cyclohexanenitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, benzyl cyanide, 2-fluorobenzoyl cyanide or 4-fluorobenzoyl cyanide, but the nitrile solvent is not limited thereto.

[0284] Because ethylene carbonate and propylene carbonate as cyclic carbonate organic solvents are high viscosity organic solvents, because dielectric constant is high and lithium salts in the electrolyte are well dissociated, so ethylene carbonate and propylene carbonate can be preferably used, and because when above-mentioned cyclic carbonate is mixed with low viscosity, linear carbonate of low dielectric constant such as dimethyl carbonate, diethyl carbonate or ethyl methyl carbonate in appropriate ratio, electrolyte with high conductivity can be prepared, so cyclic carbonate can be more preferably used. In this case, cyclic carbonate and linear carbonate can be mixed and used with a volume ratio of 2:8 to 4:6.

[0285] 7) Lithium salts

[0286] A lithium salt is used as an electrolyte salt in a lithium metal battery, where it is used as a medium for transporting ions. Generally, the lithium salt may include at least one compound selected from the following: LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiN(C2F5SO2)2, LiN(CF3SO2)2, CF3SO3Li, LiC(CF3SO2)3, LiC4BO8, LiTFSI, LiFSI, and LiClO4, and may preferably include LiPF6, but is not limited thereto. If desired, the lithium salt may be used alone or in mixtures of two or more thereof.

[0287] According to the present invention, the lithium salt in the nonaqueous electrolyte may be contained in a concentration of 0.5 M to 5 M, preferably 0.5 M to 4 M. When the concentration of the lithium salt is within the above range, the battery can be normally charged and discharged because the concentration of lithium ions in the electrolyte is appropriate and the wettability in the battery is excellent because the viscosity of the electrolyte is appropriate, thereby improving the battery performance.

[0288] 8) Other electrolyte additives

[0289] The non-aqueous electrolyte may further contain other electrolyte additives.

[0290] The other electrolyte additives are known electrolyte additives that can be added to the non-aqueous electrolyte of the present invention. For example, the other electrolyte additives can be vinylene carbonate, vinyl ethylene carbonate, catechol carbonate, α-bromo-γ-butyrolactone, methyl chloroformate, succinimide, N-benzyloxycarbonyloxysuccinimide, N-hydroxysuccinimide, N-chlorosuccinimide, methyl cinnamate, 1,3,5-tricyanobenzene, tetracyanoquinodimethane, pyrocarbonate, cyclohexylbenzene, propylene glycol, Alkane sultone, succinonitrile, adiponitrile, ethylene sulfate, propylene sultone, fluoroethylene carbonate, LiPO2F2, LiODFB (lithium difluorooxalatoborate), LiBOB (lithium bis(oxalato)borate), TMSPa (3-trimethoxysilyl-propyl-N-aniline), TMSPi (tris(trimethylsilyl) phosphite), 12-crown-4, 15-crown-5, 18-crown-6, azaethers, boranes, borates, boric acid esters, ferrocene and its derivatives or LiBF4.

[0291] The other electrolyte additives may be included in an amount of 0.01 to 10 parts by weight, preferably 0.05 to 7.0 parts by weight, and more preferably 0.05 to 5.0 parts by weight, based on 100 parts by weight of the non-aqueous electrolyte.

[0292] The lithium metal battery of the present invention can be prepared according to a typical method known in the art. For example, after forming an electrode assembly in which a separator is disposed between a positive electrode and a negative electrode, the electrode assembly is inserted into a battery case, and a lithium secondary battery can be prepared by injecting a nonaqueous electrolyte according to the present invention.

[0293] The shape of the lithium metal battery of the present invention is not particularly limited, but a cylindrical type using a can, a prismatic type, a pouch type, or a coin type may be used.

[0294] According to the present invention, a battery module including a lithium metal battery as a unit cell and a battery pack including the battery module can be provided. Since the battery module and the battery pack include a lithium metal battery having high capacity, high rate performance and high cycle characteristics, the battery module and the battery pack can be used as a power source for medium and large devices selected from electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles and power storage systems.

[0295] Preferred Embodiments

[0296] Hereinafter, the present invention will be described in detail according to specific examples. However, the following examples are only used to illustrate the present invention, and the scope of the present invention is not limited thereto. It is obvious to those skilled in the art that within the scope of the present invention and the scope of the technical spirit, multiple variants and changes are possible, and these variants and changes are all within the scope of the claims included herein.

[0297] Synthesis example

[0298] Synthesis Example 1. Preparation of Compounds of Formula Ia

[0299] After adding 3.5 equivalents of 2,2,2-trifluoroethanol to a two-necked round-bottom flask, a dropping funnel and a reflux condenser were connected, the round-bottom flask was placed in an oil bath, and then heated to 50°C, and 1 equivalent of trichlorovinylsilane was slowly added dropwise using a dropping funnel over 1 hour while nitrogen was flowing. After the addition was completed, the reactants were refluxed at 70°C while nitrogen was flowing to react overnight, and the pH value was detected after cooling to room temperature. In this case, if the pH was less than 7, it was neutralized with TEA (triethylamine), and the salt formed in the process was filtered. The residual reactants and by-products were removed under reduced pressure at room temperature, and then vacuum distilled at 60°C to obtain a compound represented by the following formula Ia.

[0300] [Formula Ia]

[0301]

[0302] The compound represented by formula Ia 1 The H-NMR data are as follows.

[0303] 1 H-NMR(400 MHz, CDCl3) δ(ppm): 6.34(1H, dd), 6.18(1H, dd), 5.85(1H,dd), 4.12(6H, q)

[0304] Synthesis Example 2. Preparation of the compound represented by formula II-a

[0305] After adding 2.5 equivalents of 2,2,2-trifluoroethanol to a two-necked round-bottom flask, a dropping funnel and a reflux condenser were connected, the round-bottom flask was placed in an oil bath, and then heated to 50°C, and 1 equivalent of dichlorovinylsilane was slowly added dropwise with a dropping funnel over 1 hour while nitrogen was flowing. After the addition was completed, the reactants were refluxed at 70°C while nitrogen was flowing to react overnight, and the pH value was detected after cooling to room temperature. In this case, if the pH was less than 7, it was neutralized with TEA (triethylamine), and the salt formed in the process was filtered. The residual reactants and by-products were removed under reduced pressure at room temperature, and then vacuum distilled at 55°C to obtain a compound represented by the following formula II-a.

[0306] [Formula II-a]

[0307]

[0308] The compound represented by formula II-a 1 The H-NMR data are as follows.

[0309] 1 H-NMR(400 MHz, CDCl3) δ(ppm): 6.32(2H, dd), 6.14(2H, dd), 5.84(2H,dd), 4.23(4H, q)

[0310] Synthesis Example 3. Preparation of the compound represented by formula III-b

[0311] In a nitrogen atmosphere and an ice bath, 1 equivalent of dichlorodimethylsilane was slowly added dropwise to a Schlenk round-bottom flask containing 2.2 equivalents of allylmagnesium bromide (1 M in ether) within 1 hour. After the addition was complete, the reaction was carried out at room temperature overnight. The reaction was terminated by dropping 5 equivalents of saturated NH4Cl aqueous solution into the corresponding flask. After the organic layer obtained by separating and removing the aqueous solution was dried with CaCl2, the precipitate was removed by filtration. The residual reactants and by-products were removed by decompression at room temperature, and then vacuum distilled at 80°C to obtain a compound represented by the following formula III-b.

[0312] [Formula III-b]

[0313]

[0314] The compound represented by formula III-b 1 The H-NMR data are as follows.

[0315] 1 H-NMR (400 MHz, CDCl3) δ (ppm): 5.77 (2H, m), 4.85 (4H, m), 1.53 (4H, d), 0.00 (6H, s)

[0316] Examples and Comparative Examples

[0317] Example 1-1

[0318] (Preparation of non-aqueous electrolyte)

[0319] A nonaqueous electrolyte was prepared by adding 1 g of the compound represented by Formula Ia to 99 g of an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 1:2 volume ratio) in which 1.0 M LiPF 6 was dissolved.

[0320] (Preparation of lithium metal symmetric battery)

[0321] A 200 μm thick lithium metal foil was used as the negative electrode and the positive electrode. After a porous polypropylene separator was placed between the negative electrode and the positive electrode in a glove box with an argon atmosphere to prepare an electrode assembly, the electrode assembly was placed in a battery case, the nonaqueous electrolyte was injected, and the battery case was sealed to prepare a coin cell type lithium metal symmetric battery.

[0322] Example 1-2

[0323] A non-aqueous electrolyte was prepared by adding 0.5 g of a compound represented by Formula Ia and 0.5 g of a compound represented by Formula II-a to 99 g of an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 1:2 volume ratio) in which 1.0 M LiPF6 was dissolved. A lithium metal symmetric battery was prepared in the same manner as in Example 1-1 except that the non-aqueous electrolyte prepared as described above was used.

[0324] Examples 1-3

[0325] A non-aqueous electrolyte was prepared by adding 0.5 g of a compound represented by Formula Ia and 0.5 g of a compound represented by Formula III-b to 99 g of an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 1:2 volume ratio) in which 1.0 M LiPF6 was dissolved. A lithium metal symmetric battery was prepared in the same manner as in Example 1-1 except that the non-aqueous electrolyte prepared as described above was used.

[0326] Examples 1-4

[0327] A non-aqueous electrolyte was prepared by adding 0.5 g of a compound represented by Formula Ia and 0.5 g of a compound represented by Formula IV-a (Sigma-Aldrich) to 99 g of an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 1:2 volume ratio) in which 1.0 M LiPF6 was dissolved. A lithium metal symmetric battery was prepared in the same manner as in Example 1-1 except that the non-aqueous electrolyte prepared as described above was used.

[0328] Examples 1-5

[0329] A non-aqueous electrolyte was prepared by adding 0.5 g of a compound represented by Formula Ia and 0.5 g of a compound represented by Formula Vb (2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (Tokyo Chemical Industry, Co., Ltd.)) to 99 g of an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 1:2 volume ratio) in which 1.0 M LiPF6 was dissolved. A lithium metal symmetrical battery was prepared in the same manner as in Example 1-1 except that the non-aqueous electrolyte prepared as described above was used.

[0330] Comparative Example 1-1

[0331] A lithium metal symmetrical battery was prepared in the same manner as in Example 1-1, except that an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 3:7 volume ratio) in which 1.0 M LiPF6 was dissolved was used as the non-aqueous electrolyte instead of the non-aqueous electrolyte of Example 1-1.

[0332] Comparative Example 1-2

[0333] A non-aqueous electrolyte was prepared by adding 1 g of 1,3-propane sultone (Sigma-Aldrich) to 99 g of an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 1:2 volume ratio) in which 1.0 M LiPF6 was dissolved. A lithium metal symmetric cell was prepared in the same manner as in Example 1-1 except that the non-aqueous electrolyte prepared as described above was used.

[0334] Comparative Examples 1-3

[0335] A non-aqueous electrolyte was prepared by adding 1 g of TEOS (tetraethoxysilane) (Sigma-Aldrich) to 99 g of an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 1:2 volume ratio) in which 1.0 MLiPF6 was dissolved. A lithium metal symmetric cell was prepared in the same manner as in Example 1-1 except that the non-aqueous electrolyte prepared as described above was used.

[0336]

[0337] Example 2-1

[0338] (Preparation of non-aqueous electrolyte)

[0339] A nonaqueous electrolyte was prepared by adding 1 g of the compound represented by Formula Ia to 99 g of an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 1:2 volume ratio) in which 1.0 M LiPF 6 was dissolved.

[0340] (Preparation of lithium metal batteries)

[0341] The positive electrode active material (LiNi 0.8 Co 0.1 Mn 0.1 O2): conductive material (carbon black): binder (polyvinylidene fluoride) was added to N-methyl-2-pyrrolidone (NMP) at a weight ratio of 90:5:5 to prepare a positive electrode active material slurry. Both surfaces of a 15 μm thick positive electrode collector (Al film) were coated with the positive electrode active material slurry to a thickness of 59 μm, dried, and rolled using a calender to prepare a positive electrode (width: 12 mm, length: 12 mm, thickness: 74 μm).

[0342] A 200 μm thick lithium metal foil was used as the negative electrode. After a porous polypropylene separator was placed between the negative electrode and the positive electrode in a glove box with an argon atmosphere to prepare an electrode assembly, the electrode assembly was placed in a battery case, the nonaqueous electrolyte was injected, and the battery case was sealed to prepare a coin cell type lithium metal battery.

[0343] Example 2-2

[0344] A non-aqueous electrolyte was prepared by adding 0.5 g of a compound represented by Formula Ia and 0.5 g of a compound represented by Formula II-a to 99 g of an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 1:2 volume ratio) in which 1.0 M LiPF6 was dissolved. A lithium metal battery was prepared in the same manner as in Example 2-1 except that the non-aqueous electrolyte prepared as described above was used.

[0345] Example 2-3

[0346] A non-aqueous electrolyte was prepared by adding 0.5 g of a compound represented by Formula Ia and 0.5 g of a compound represented by Formula III-b to 99 g of an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 1:2 volume ratio) in which 1.0 M LiPF6 was dissolved. A lithium metal battery was prepared in the same manner as in Example 2-1 except that the non-aqueous electrolyte prepared as described above was used.

[0347] Embodiment 2-4

[0348] A non-aqueous electrolyte was prepared by adding 0.5 g of a compound represented by Formula Ia and 0.5 g of a compound represented by Formula IV-a to 99 g of an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 1:2 volume ratio) in which 1.0 M LiPF6 was dissolved. A lithium metal battery was prepared in the same manner as in Example 2-1 except that the non-aqueous electrolyte prepared as described above was used.

[0349] Embodiment 2-5

[0350] A non-aqueous electrolyte was prepared by adding 0.5 g of a compound represented by Formula Ia and 0.5 g of a compound represented by Formula Vb (2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (Tokyo Chemical Industry Co., Ltd.)) to 99 g of an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 1:2 volume ratio) in which 1.0 M LiPF6 was dissolved. A lithium metal battery was prepared in the same manner as in Example 2-1 except that the non-aqueous electrolyte prepared as described above was used.

[0351] Comparative Example 2-1

[0352] A lithium metal battery was prepared in the same manner as in Example 2-1, except that an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 3:7 volume ratio) in which 1.0 M LiPF6 was dissolved was used instead of the non-aqueous electrolyte of Example 2-1.

[0353] Comparative Example 2-2

[0354] A non-aqueous electrolyte was prepared by adding 1 g of 1,3-propane sultone (Sigma-Aldrich) to 99 g of an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 1:2 volume ratio) in which 1.0 MLiPF6 was dissolved. A lithium metal battery was prepared in the same manner as in Example 2-1 except that the non-aqueous electrolyte prepared as described above was used.

[0355] Comparative Example 2-3

[0356] A non-aqueous electrolyte was prepared by adding 1 g of TEOS (tetraethoxysilane) (Sigma-Aldrich) to 99 g of an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 1:2 volume ratio) in which 1.0 MLiPF6 was dissolved. A lithium metal battery was prepared in the same manner as in Example 2-1 except that the non-aqueous electrolyte prepared as described above was used.

[0357] Experimental example

[0358] Experimental Example 1: Evaluation of Lithium Metal Symmetric Battery Characteristics

[0359] The activation process was performed in which the lithium metal symmetrical batteries prepared in Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-3 were charged / discharged at 25° C. at 0.2 mA / cm 2 The initial charge / discharge process was then repeated for 500 cycles at a current density of 1.0 mA / cm 2 Each battery is charged for 1 hour and discharged for 1 hour as one cycle. In this case, the current density is 0.2 mA / cm 2 The overvoltage generated in the first cycle (overvoltage during activation) and the overvoltage at a current density of 1.0 mA / cm 2 The overvoltages generated in the 1st cycle, 100th cycle, 200th cycle and 300th cycle are shown in Table 3 below.

[0360]

[0361] As shown in Table 3, for Examples 1-1 to 1-5, the voltage was kept low and the lifespan characteristics were improved compared with Comparative Examples 1-1 to 1-3.

[0362] For Examples 1-1 to 1-5, an SEI layer having high structural flexibility and stability was formed on the lithium metal foil, and thus since plating / stripping occurred uniformly, it can be considered that the life and stability of the lithium metal battery were improved. On the contrary, for Comparative Examples 1-1 to 1-3, it can be confirmed that plating / stripping occurred unevenly on the lithium metal foil.

[0363] Experimental Example 2: Cycle Characteristics Evaluation

[0364] The lithium metal batteries of Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-3 were charged to 4.3 V at a rate of 0.1 C and 0.05 C cut-off at 25° C. under constant current / constant voltage conditions using a charger / discharger, and then the lithium metal batteries were discharged to 3.0 V for two cycles. Subsequently, the lithium metal battery was charged at a rate of 0.1 C and 0.05 C cut-off under constant current / constant voltage conditions using a charger / discharger, and then the lithium metal battery was discharged to 3.0 V for 100 cycles. In this case, the capacity after the 1st cycle and the discharge capacity after the 100th cycle were measured, and the discharge capacity retention rate (discharge capacity after the 100th cycle / discharge capacity after the 1st cycle×100) was calculated and shown in Table 4 below.

[0365]

[0366] As shown in Table 4, for Examples 2-1 to 2-5, the discharge capacity retention ratio at the 100th cycle was improved compared with Comparative Examples 2-1 to 2-3.

[0367] The reason for this characteristic is that the silane additive contained in the non-aqueous electrolyte of Examples 2-1 to 2-5 effectively forms a highly stable and strong SEI layer. Specifically, the reason is that because the silane additive represented by Formula I forms a covalent bond ([Li]-O-Si-O-) with the electrode, an SEI layer that is not significantly affected by volume changes, i.e., excellent in mechanical rigidity, is formed. As a result, because a Li-Si-O network is formed between the negative electrode and the additive and an -O-Si-O-Si-O-network is formed between the SEI layer and the additive, it can be considered that the stability problem caused by the formation of lithium dendrites during charge and discharge is solved.

[0368] In addition, the reason for this is that, since the silane-based additive represented by Formula I contains a fluorine element, it becomes a source of fluorine anions during a reduction / oxidation decomposition reaction, and thus it contributes to the formation of a SEI layer based on LiF, which is a stable inorganic compound included in the SEI layer.

[0369] Furthermore, the reason for this is that, since the silane-based additive represented by Formula I contains an alkenyl group, it forms a CC bond through a reduction / oxidation decomposition reaction to form an SEI layer in a polymer form.

Claims

1. A lithium metal battery, comprising: positive electrode; Lithium metal anode; A separator disposed between the positive electrode and the lithium metal negative electrode; and A non-aqueous electrolyte comprising an organic solvent, a lithium salt and a compound represented by Formula I: [Formula I] in, In Formula I, R a is a C1-C 10 alkyl, R b Each independently is C1-C 10 alkyl, R' is independently hydrogen; unsubstituted or substituted C1-C 10 Alkyl; or unsubstituted or substituted C1-C 10 heteroalkyl, and R'' is unsubstituted or substituted C2-C 10 Alkenyl; or unsubstituted or substituted C2-C 10 Alkynyl.

2. The lithium metal battery according to claim 1, wherein the non-aqueous electrolyte further comprises at least one compound selected from the group consisting of compounds represented by Formula II to Formula V: [Formula II] [Formula III] [Formula IV] Si(R'')4 [Formula V] in, In Formula II to Formula V, R b Each independently is C1-C 10 alkyl, R c are each independently unsubstituted or substituted C1-C 10 alkyl, R' is independently hydrogen; unsubstituted or substituted C1-C 10 Alkyl; or unsubstituted or substituted C1-C 10 Heteroalkyl, R'' is unsubstituted or substituted C2-C 10 Alkenyl; or unsubstituted or substituted C2-C 10 Alkynyl, R d and R e are each independently hydrogen; unsubstituted or substituted C1-C 10 Alkyl; unsubstituted or substituted C1-C 10 heteroalkyl; or unsubstituted or substituted siloxane, Among them, in R d and R e When all of them are siloxane groups, R d and R e are connected to each other to form a ring consisting of siloxane bonds, and n is 2 or 3.

3. The lithium metal battery according to claim 2, wherein the compound represented by formula I is at least one compound selected from the compounds of formulas Ia to If: [Formula Ia] [Formula Ib] [Formula Ic] [FormulaId] [Formula Ie] [Formula If] 。 4. The lithium metal battery according to claim 2, wherein the compound represented by formula II is at least one compound selected from the compounds of formula II-a to formula II-f: [Formula II-a] [Formula II-b] [Formula II-c] [Formula II-d] [Formula II-e] [Formula II-f] 。 5. The lithium metal battery according to claim 2, wherein the compound represented by formula III is at least one compound selected from the compounds of formula III-a to formula III-o: [Formula III-a] [Formula III-b] [Formula III-c] [Formula III-d] [Formula III-e] [Formula III-f] [Formula III-g] [Formula III-h] [Formula III-i] [Formula III-j] [Formula III-k] [Formula III-1] [Formula III-m] [Formula III-n] [Formula III-o] 。 6. The lithium metal battery according to claim 2, wherein the compound represented by formula IV is at least one compound selected from the compounds of formula IV-a to formula IV-c: [Formula IV-a] [Formula IV-b] [Formula IV-c] 。 7. The lithium metal battery according to claim 2, wherein the compound represented by formula V is at least one compound selected from the group consisting of compounds of formula Va and formula Vb: [Formula Va] [Formula Vb] 。

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