Lithium metal battery

Abstract

The present invention relates to a lithium metal battery with improved lifespan and stability, comprising a positive electrode, a lithium metal negative electrode, a separator interposed 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 herein.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0126772, dated October 5, 2022, and all contents disclosed in the documents of this Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a lithium metal battery containing a non-aqueous electrolyte solution containing a silane-based compound. [Background technology]

[0003] In recent years, interest in energy storage technology has been growing, and among electrochemical devices, secondary batteries that can be charged and discharged have been attracting attention. In particular, lithium secondary batteries, developed in the early 1990s, have attracted attention due to their advantages of high operating voltage and extremely high energy density. A lithium secondary battery consists of a negative electrode containing a negative electrode active material such as a carbon material or a silicon material that can insert and extract lithium ions, a positive electrode containing a positive electrode active material such as a lithium-containing oxide, and a non-aqueous electrolyte solution in which a lithium salt is dissolved in an organic solvent.

[0004] Lithium metal batteries are secondary lithium batteries that use lithium metal or lithium alloys in the negative electrode. Lithium has a high specific capacity of about 3,860 mAh / g, a very low standard redox potential (-3.04 V vs. SHE), and a low density (0.534 g / cm 3 ) and is known as the most suitable material that can replace a negative electrode containing a negative electrode active material such as a carbon material or a silicon material.

[0005] In lithium metal batteries, an SEI layer, consisting of decomposition products formed by chemical reactions with the electrolyte, forms on the surface of the lithium metal anode. Furthermore, localized lithium electrodeposition occurs, and lithium grows in a dendritic (tree-like) shape, forming lithium dendrites, which can lead to internal short circuits in the battery. Furthermore, uneven lithium electrodeposition can generate dead lithium and damage the existing SEI layer. This can expose the surface of the lithium metal anode, leading to chain decomposition of the electrolyte, resulting in problems such as reduced battery capacity, stability, and lifespan, as well as increased battery resistance. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention is intended to solve the above problems, and has as its object to provide a lithium metal battery with improved life characteristics. [Means for solving the problem]

[0007] (1) The present invention provides a lithium metal battery comprising a positive electrode, a lithium metal negative electrode, a separator interposed between the positive electrode and the lithium metal negative electrode, and a non-aqueous electrolyte solution containing an organic solvent, a lithium salt, and a compound represented by the following chemical formula I:

[0008] [ka]

[0009] In the above chemical formula I, R a is a C1-C substituted with one or more fluorine atoms. 10 is an alkyl group of the formula R b are each independently a C-C group which may or may not be substituted with one or more fluorine atoms.10 is an alkyl group of the formula R' are each independently hydrogen; substituted or unsubstituted C-C 10 or a substituted or unsubstituted C1-C 10 is a heteroalkyl group of the formula R'' is a substituted or unsubstituted C2-C 10 or a substituted or unsubstituted C-C alkenyl group 10 is an alkynyl group of the formula:

[0010] (2) The present invention provides the lithium metal battery according to (1) above, wherein the non-aqueous electrolyte solution further contains one or more compounds selected from the group consisting of compounds represented by the following chemical formulas II to V:

[0011] [ka]

[0012] [ka]

[0013] [Chemical formula IV] Si(R'')4

[0014] [ka]

[0015] In the above chemical formulas II to V, R b are each independently a C-C group which may or may not be substituted with one or more fluorine atoms. 10 is an alkyl group of the formula R c are each independently a substituted or unsubstituted C-C 10 is an alkyl group of the formula R' are each independently hydrogen; substituted or unsubstituted C-C 10 or a substituted or unsubstituted C1-C 10 is a heteroalkyl group of the formula R'' is a substituted or unsubstituted C2-C 10 or a substituted or unsubstituted C-C alkenyl group 10 is an alkynyl group of the formula R d and R e are each independently hydrogen; a substituted or unsubstituted C-C 10 alkyl groups of the formula: substituted or unsubstituted C1-C 10 or a substituted or unsubstituted siloxane group, R d and R e When both of R and R are siloxane groups, R d and R e may be linked to each other to form a ring consisting of siloxane bonds, n is 2 or 3.

[0016] (3) The present invention provides the lithium metal battery according to (2) above, wherein the compound represented by chemical formula I is one or more compounds selected from the compounds represented by the following chemical formulae Ia to If:

[0017] [ka]

[0018] [ka]

[0019] [ka]

[0020] [ka]

[0021] [ka]

[0022] [ka]

[0023] (4) The present invention provides the lithium metal battery according to (2) or (3) above, wherein the compound represented by chemical formula II is one or more compounds selected from the compounds represented by the following chemical formulae II-a to II-f:

[0024] [ka]

[0025] [ka]

[0026] [ka]

[0027] [ka]

[0028] [ka]

[0029] [ka]

[0030] (5) The present invention provides the lithium metal battery according to any one of (2) to (4) above, wherein the compound represented by chemical formula III is one or more compounds selected from the compounds represented by the following chemical formulae III-a to III-o:

[0031] [ka]

[0032] [ka]

[0033] [ka]

[0034] [ka]

[0035] [ka]

[0036] [ka]

[0037] [ka]

[0038] [ka]

[0039] [ka]

[0040] [ka]

[0041] [ka]

[0042] [ka]

[0043] [ka]

[0044] [ka]

[0045] [ka]

[0046] (6) The present invention provides the lithium metal battery according to any one of (2) to (5) above, wherein the compound represented by chemical formula IV is one or more compounds selected from the compounds represented by the following chemical formulas IV-a to IV-c:

[0047] [ka]

[0048] [ka]

[0049] [ka]

[0050] (7) The present invention provides the lithium metal battery according to any one of (2) to (6) above, wherein the compound represented by chemical formula V is one or more compounds selected from the compounds represented by chemical formulas Va and Vb below:

[0051] [ka]

[0052] [ka] [Effects of the Invention]

[0053] When the compound represented by Chemical Formula I, which is a silane-based compound, is contained in the non-aqueous electrolyte solution as in the present invention, an SEI layer having 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, thereby providing a lithium metal battery with excellent stability and life characteristics. DETAILED DESCRIPTION OF THE INVENTION

[0054] The present invention will now be described in more detail.

[0055] The terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, based on the principle that the inventors can appropriately define the concepts of terms in order to best explain their inventions.

[0056] The terms used in the present invention are merely used to describe specific embodiments and are not intended to limit the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise. In the present invention, the terms "comprise" or "have" and the like are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should not be understood to preclude the presence or possibility of addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0057] The present invention provides a lithium metal battery including a positive electrode, a lithium metal negative electrode, a separator interposed between the positive electrode and the lithium metal negative electrode, and a non-aqueous electrolyte solution including an organic solvent, a lithium salt, and a compound represented by the following chemical formula I:

[0058] [ka]

[0059] In the above chemical formula I, R a is a C1-C substituted with one or more fluorine atoms. 10 is an alkyl group of the formula R b are each independently a C-C group which may or may not be substituted with one or more fluorine atoms. 10 is an alkyl group of the formula R' are each independently hydrogen; substituted or unsubstituted C-C 10 or a substituted or unsubstituted C1-C 10 is a heteroalkyl group of the formula R'' is a substituted or unsubstituted C2-C 10 or a substituted or unsubstituted C-C alkenyl group 10 is an alkynyl group of the formula:

[0060] In the present invention, in the case of a substituted alkyl group; a substituted heteroalkyl group; a substituted alkenyl group; a substituted alkynyl group; or a substituted siloxane group, the substituent may be a deuterium (-D), a hydroxy 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), 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 (-OP(OR)2), phosphate (-OPO(OR)2), phosphinate (-PO(OR)R), phosphinite (-P(OR)R2), phosphonate (-PO3R2), phosphonite (-P(OR)2), boronic acid In this case, in the substituent, X may be a halogen group, and each R may be independently selected from the group consisting of C1-C6, ... 10 Alkyl groups of C2-C 10 or C2-C 10 The alkynyl group may be:

[0061] The inventors of the present invention have found that when a compound represented by Formula I is added to a non-aqueous electrolyte of a lithium metal battery, a covalent bond ([electrode]-O-Si-O-) is formed between the compound represented by Formula I and hydroxy groups on the surface of the anode or cathode (hydroxy groups of LiOH present on the surface of a lithium metal anode; in the case of a cathode, hydroxy groups present on the surface of a cathode active material (e.g., lithium metal oxide)). This results in the formation of an SEI layer that is not significantly affected by volume change, i.e., has excellent mechanical rigidity. Specifically, when the anode is a lithium metal anode, a Li-Si-O network is formed between the anode and the additive, and an -O-Si-O-Si-O- network is formed between the SEI layer and the additive, thereby protecting the lithium metal anode, which has stability issues due to the formation of lithium dendrites during charge and discharge.

[0062] The Li-Si-O network between the negative electrode and the additive provides Li at the interface between the negative electrode and the electrolyte. + This has the function of promoting the movement of the electrolyte, preventing an increase in resistance within the battery, and preventing a decrease in battery performance even when the battery is rapidly charged.

[0063] The compound represented by Formula I contains fluorine and serves as a source of fluorine anions during reduction / oxidation decomposition, thereby assisting in the formation of LiF, a stable inorganic compound contained in the SEI layer.The compound represented by Formula I also contains a substituted or unsubstituted alkenyl group or a substituted or unsubstituted alkynyl group, and can form a C-C bond during reduction / oxidation decomposition to form a polymeric SEI layer.

[0064] As a result, the battery according to the present invention, although being a lithium metal battery, has an SEI layer formed thereon that has high structural flexibility and stability, and is characterized by excellent high-temperature stability and life characteristics.

[0065] (1) Positive electrode The positive electrode can be manufactured by coating a positive electrode slurry containing a positive electrode active material, a binder, a conductive material, a solvent, etc. on a positive electrode current collector.

[0066] The positive electrode current collector is not particularly limited as long as it does not cause a chemical change in the battery and has conductivity. For example, stainless steel, aluminum, nickel, titanium, fired carbon, or those obtained by surface treatment of the surface of aluminum or stainless steel with carbon, nickel, titanium, silver, etc. may be used. Also, the binding force of the positive electrode active material may be strengthened by forming fine irregularities on the surface, and it can be used in various forms such as films, sheets, foils, meshes, porous bodies, foams, non-woven bodies, etc.

[0067] The positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium. Specifically, it may include a lithium metal oxide containing one or more metals such as cobalt, manganese, nickel, or aluminum and lithium. More specifically, the lithium metal oxide is a lithium-manganese-based oxide (e.g., LiMnO2, LiMn2O4, etc.), a lithium-cobalt-based oxide (e.g., LiCoO2, etc.), a lithium-nickel-based oxide (e.g., LiNiO2, etc.), a lithium-nickel-manganese-based oxide (e.g., LiNi 1-Y Mn Y O2 (where 0 < Y < 1), LiMn 2-Z Ni Z O4 (where 0 < Z < 2), etc.), a lithium-nickel-cobalt-based oxide (e.g., LiNi 1-Y1 Co Y1 O2 (where 0 < Y1 < 1), etc.), a lithium-manganese-cobalt-based oxide (e.g., LiCo 1-Y2 Mn Y2 O2 (where 0 < Y2 < 1), LiMn 2-Z1 Co Z1 O4 (where {0 < Z1 < 2}), etc.), a lithium-nickel-manganese-cobalt-based oxide (e.g., 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) oxide (e.g., Li(Ni p2 Co q2 Mn r3 M s2 )O2 (where M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, and Mo, and p2, q2, r3, and s2 are the atomic fractions of the respective independent elements, 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1, and p2 + q2 + r3 + s2 = 1), etc.), and any one or more of these compounds may be included.

[0068] Among them, from the point of view of being able to improve the capacity characteristics and stability of the battery, the lithium metal oxide is LiCoO2, LiMnO2, LiNiO2, lithium nickel manganese cobalt oxide (e.g., 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 oxide (e.g., Li(Ni 0.8 Co 0.15 Al 0.05 )O2, etc.), and considering the significance of the improvement effect by controlling the types and content ratios of the constituent elements forming the lithium composite metal oxide, the lithium composite metal oxide is Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni0.5 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., and any one or a mixture of two or more of these can be used.

[0069] The positive electrode active material may be contained in an amount of 60 to 99% by weight, preferably 70 to 99% by weight, and more preferably 80 to 98% by weight, based on the total weight of solids in the positive electrode slurry excluding the solvent.

[0070] The binder is a component that assists in binding the active material and the conductive material and in binding them to the current collector.

[0071] Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene (PE), polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, and various copolymers.

[0072] Generally, the binder may be contained in an amount of 1 to 20% by weight, preferably 1 to 15% by weight, and more preferably 1 to 10% by weight, based on the total weight of the solid content excluding the solvent in the positive electrode slurry.

[0073] The conductive material is a component for further improving the conductivity of the positive electrode active material.

[0074] The conductive material is not particularly limited as long as it does not cause a chemical change in the battery and has conductivity, and examples thereof include graphite; carbon-based substances such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0075] Generally, the conductive material may be contained in an amount of 1 to 20% by weight, preferably 1 to 15% by weight, and more preferably 1 to 10% by weight, based on the total weight of the solid content excluding the solvent in the positive electrode slurry.

[0076] The solvent may include an organic solvent such as NMP (N-methyl-2-pyrrolidone) and may be used in an amount that provides a suitable viscosity when the positive electrode active material, and optionally a binder and a conductive material, are contained. For example, the solvent may be contained so that the concentration of the solids including the positive electrode active material, and optionally a binder and a conductive material, is 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.

[0077] (2) Lithium metal anode The anode is a lithium metal anode, and can be fabricated by physically bonding, extruding, rolling, or depositing lithium on a lithium thin film or an anode current collector. The deposition method can be metal electrolytic deposition or chemical vapor deposition.

[0078] When the negative electrode is manufactured by physically bonding, rolling, or vapor-depositing lithium onto the negative electrode current collector, the negative electrode current collector generally has a thickness of 3 to 500 μm. Such a negative electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like, aluminum-cadmium alloy, etc. may be used. Furthermore, as with the positive electrode current collector, the bonding strength may be strengthened by forming fine irregularities on the surface, and the negative electrode current collector may be used in various forms such as a film, sheet, foil, net, porous material, foam, or nonwoven fabric.

[0079] (3) Separator The separator may be a conventional porous polymer film, such as a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, or an ethylene / methacrylate copolymer, either alone or in a laminate, or a conventional porous nonwoven fabric, such as a nonwoven fabric made of a high-melting point glass fiber, polyethylene terephthalate fiber, etc., but is not limited to these. Furthermore, to ensure heat resistance or mechanical strength, a coated separator containing a ceramic component or a polymer material may be used, and may be selectively used as a single-layer or multi-layer structure.

[0080] (4) Non-aqueous electrolyte The non-aqueous electrolyte according to the present invention comprises an organic solvent, a lithium salt, and a compound represented by the following chemical formula I:

[0081] [ka]

[0082] In the above chemical formula I, R a is a C1-C substituted with one or more fluorine atoms.10 is an alkyl group of the formula R b are each independently a C-C group which may or may not be substituted with one or more fluorine atoms. 10 is an alkyl group of the formula R' are each independently hydrogen; substituted or unsubstituted C-C 10 or a substituted or unsubstituted C1-C 10 is a heteroalkyl group of the formula R'' is a substituted or unsubstituted C2-C 10 or a substituted or unsubstituted C-C alkenyl group 10 is an alkynyl group of the formula:

[0083] According to the present invention, the non-aqueous electrolyte may further include one or more compounds selected from the group consisting of compounds represented by the following formulas II to V.

[0084] [ka]

[0085] [ka]

[0086] [Chemical formula IV] Si(R'')4

[0087] [ka]

[0088] In the above chemical formulas II to V, R b are each independently a C-C group which may or may not be substituted with one or more fluorine atoms. 10 is an alkyl group of the formula R care each independently a substituted or unsubstituted C-C 10 is an alkyl group of the formula R' are each independently hydrogen; substituted or unsubstituted C-C 10 or a substituted or unsubstituted C1-C 10 is a heteroalkyl group of the formula R'' is a substituted or unsubstituted C2-C 10 or a substituted or unsubstituted C-C alkenyl group 10 is an alkynyl group of the formula R d and R e are each independently hydrogen; a substituted or unsubstituted C-C 10 alkyl groups of the formula: substituted or unsubstituted C1-C 10 or a substituted or unsubstituted siloxane group, R d and R e When both of R and R are siloxane groups, R d and R e may be linked to each other to form a ring consisting of siloxane bonds, n is 2 or 3.

[0089] The non-aqueous electrolyte solution according to the present invention may contain the compound represented by the chemical formula I and one or more compounds selected from the compounds represented by the chemical formulas II to V. That is, the nonaqueous electrolyte according to the present invention may contain both compounds represented by chemical formula I and chemical formula II, both compounds represented by chemical formula I and chemical formula III, both compounds represented by chemical formula I and chemical formula IV, both compounds represented by chemical formula I and chemical formula V, both compounds represented by chemical formula I, chemical formula II, and chemical formula III, both compounds represented by chemical formula I, chemical formula II, and chemical formula IV, both compounds represented by chemical formula I, chemical formula II, and chemical formula V, both compounds represented by chemical formula I, chemical formula III, and chemical formula IV, both compounds represented by chemical formula I, chemical formula III, and chemical formula V, both compounds represented by chemical formula I to IV, both compounds represented by chemical formula I, chemical formula II, chemical formula III, and chemical formula V, both compounds represented by chemical formula I, chemical formula II, chemical formula IV, and chemical formula V, or both compounds represented by chemical formula I, chemical formula III, chemical formula IV, and chemical formula V.

[0090] When the compound represented by Chemical Formula I and one or more compounds selected from the compounds represented by Chemical Formulas II to V are contained in a non-aqueous electrolyte, a thin and stable SEI layer is formed, and a lithium secondary battery having excellent high-temperature stability and life characteristics can be provided. In particular, when a lithium metal negative electrode is used as the negative electrode of the lithium secondary battery, a thin and stable SEI layer containing not only siloxane bonds but also carbon-carbon bonds is formed, further improving the stability and life characteristics of the battery.

[0091] 1) A compound represented by chemical formula I The compound represented by Chemical Formula I forms a covalent bond ([electrode]-O-Si-O-) with a hydroxy group on the surface of the negative electrode or positive electrode (a hydroxy group of LiOH present on the surface of a lithium metal negative electrode; in the case of a positive electrode, a hydroxy group present on the surface of a positive electrode active material (e.g., lithium metal oxide)), thereby forming an SEI layer with excellent mechanical rigidity. Specifically, when the negative electrode is a lithium metal negative electrode, 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, thereby protecting the lithium metal negative electrode, which has stability issues due to the formation of lithium dendrites during charge and discharge. The Li-Si-O network between the negative electrode and the additive prevents Li from adsorbing at the interface between the negative electrode and the electrolyte. + This has the function of promoting the movement of the electrolyte, preventing an increase in resistance within the battery, and preventing a decrease in battery performance even when the battery is rapidly charged.

[0092] The compound represented by Formula I contains fluorine and serves as a source of fluorine anions during reduction / oxidation decomposition, thereby assisting in the formation of LiF, a stable inorganic compound contained in the SEI layer.The compound represented by Formula I also contains a substituted or unsubstituted alkenyl group or a substituted or unsubstituted alkynyl group, and can form a C-C bond during reduction / oxidation decomposition to form a polymeric SEI layer.

[0093] As a result, the battery according to the present invention, although being a lithium metal battery, has an SEI layer formed thereon that has high structural flexibility and stability, and is characterized by excellent high-temperature stability and life characteristics.

[0094] In the above formula I, R a Specifically, may be a C1-C6 alkyl group substituted with one or more fluorine atoms, more specifically, a C1-C5 alkyl group substituted with one or more fluorine atoms. In this case, more fluorine atoms can be supplied, and a more stable SEI layer of the LiF component can be expected to be formed.

[0095] In the above formula I, R b are specifically, each independently a C-C substituted with one or more fluorine atoms. 10 The alkyl groups may be C1-C6 alkyl groups, more specifically, each independently substituted with one or more fluorine atoms, and more specifically, each independently substituted with one or more fluorine atoms. In this case, the alkyl groups may serve as a source of fluorine anions during the reduction / oxidation decomposition reaction, thereby forming a stable LiF-based SEI layer. Therefore, in a lithium metal battery using a nonaqueous electrolyte containing the compound represented by Formula I, the electrode life can be improved and battery swelling caused by electrolyte decomposition at high temperatures can be effectively reduced.

[0096] In the formula I, each R' is specifically independently hydrogen; or a substituted or unsubstituted C-C 10 More specifically, each independently may be hydrogen or a substituted C1-C6 alkyl group, more specifically, each independently may be hydrogen or a substituted C1-C5 alkyl group, where the substituent may specifically be a fluoro group.

[0097] In the formula I, R″ is specifically an unsubstituted C2-C 10 or unsubstituted C2-C 10 or an unsubstituted C2-C6 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 undergo a reduction / oxidation decomposition reaction at the interface between the two electrodes to form a polymeric SEI layer.

[0098] According to the present invention, the compound represented by the formula I may be one or more compounds selected from the compounds represented by the following formulas Ia to If:

[0099] [ka]

[0100] [ka]

[0101] [ka]

[0102] [ka]

[0103] [ka]

[0104] [ka]

[0105] Meanwhile, according to the present invention, the non-aqueous electrolyte may include the compound represented by Formula I in an amount of 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, per 100 parts by weight of the non-aqueous electrolyte. When the content of the compound represented by Formula I is within the above range, when the non-aqueous electrolyte is applied to a lithium metal battery, the SEI layer derived from the compound represented by Formula I has an appropriate thickness that allows smooth lithium ion movement and has strong mechanical rigidity, thereby improving stability and preventing an increase in the internal resistance of the lithium metal battery and a decrease in battery capacity.

[0106] Meanwhile, the compound represented by the formula I can be prepared by, but is not limited to, substituting an alcohol for the halogen atom of a silane compound containing Si directly bonded to the halogen atom. For example, the compound can be prepared by introducing an alkyne into a silane compound represented by SiH(OR)3 in the presence of a transition metal catalyst, as described in Organometallics, 2011, Vol. 30, No. 2, pp. 352-355.

[0107] 2) A compound represented by formula II The compound represented by Formula II has two or more substituted or unsubstituted alkenyl groups or substituted or unsubstituted alkynyl groups, and therefore can effectively assist in the formation of an SEI layer as a crosslinker, resulting in the formation of a stronger SEI layer. The formation of such a stable SEI layer can extend the life of the electrode or effectively reduce battery swelling caused by electrolyte decomposition.

[0108] Furthermore, the compound represented by the chemical formula II contains a fluorine element and serves as a source of fluorine anions during the reduction / oxidation decomposition reaction, thereby helping to form LiF, a stable inorganic compound contained in the SEI layer.

[0109] According to the present invention, in the above chemical formula II, R b are specifically, each independently a C-C substituted with one or more fluorine atoms. 10 More specifically, each independently may be a C1-C6 alkyl group substituted with one or more fluorine atoms, and more specifically, each independently may be a C1-C5 alkyl group substituted with one or more fluorine atoms. For example, b may be a C1-C5 alkyl group containing a trifluoro group.

[0110] According to the present invention, in the formula II, R' is specifically selected from the group consisting of hydrogen, unsubstituted C1-C 10 or an unsubstituted C1-C6 alkyl group, more specifically, each independently hydrogen; or an unsubstituted C1-C5 alkyl group.

[0111] According to the present invention, in the formula II, R″ is specifically an unsubstituted C2-C 10 or unsubstituted C2-C 10 or an unsubstituted C2-C6 alkynyl group, more particularly an unsubstituted C2-C6 alkenyl group; or an unsubstituted C2-C6 alkynyl group, more particularly an unsubstituted C2-C5 alkenyl group; or an unsubstituted C2-C5 alkynyl group.

[0112] According to the present invention, the compound represented by the formula II may be one or more compounds selected from the compounds represented by the following formulas II-a to II-f:

[0113] [ka]

[0114] [ka]

[0115] [ka]

[0116] [ka]

[0117] [ka]

[0118] [ka]

[0119] 3) A compound represented by formula III The compound represented by Formula III has two or more substituted or unsubstituted alkenyl groups or substituted or unsubstituted alkynyl groups, and therefore can effectively assist in the formation of an SEI layer as a crosslinker, resulting in the formation of a stronger SEI layer. The formation of such a stable SEI layer can extend the life of the electrode or effectively reduce battery swelling caused by electrolyte decomposition.

[0120] According to the present invention, in the above chemical formula III, R C are specifically, each independently, unsubstituted C-C 10 alkyl groups; C1-C substituted with one or more fluorine atoms 10 or C1-C substituted with a cyano group 10 The R C More specifically, each independently represents an unsubstituted C1-C6 alkyl group; a C1-C6 alkyl group substituted with one or more fluorine atoms; 10 or a C1-C6 alkyl group substituted with a cyano group.

[0121] According to the present invention, in the formula III, R″ is specifically an unsubstituted C2-C 10 or unsubstituted C2-C 10 or an unsubstituted C2-C6 alkynyl group, more particularly an unsubstituted C2-C6 alkenyl group; or an unsubstituted C2-C6 alkynyl group, more particularly an unsubstituted C2-C5 alkenyl group; or an unsubstituted C2-C5 alkynyl group.

[0122] According to the present invention, the compound represented by the formula III may be one or more compounds selected from the compounds represented by the following formulae III-a to III-o:

[0123] [ka]

[0124] [ka]

[0125] [ka]

[0126] [ka]

[0127] [ka]

[0128] [ka]

[0129] [ka]

[0130] [ka]

[0131] [ka]

[0132] [ka]

[0133] [ka]

[0134] [ka]

[0135] [ka]

[0136] [ka]

[0137] [ka]

[0138] 4) Compound represented by formula IV The compound represented by Formula IV has two or more substituted or unsubstituted alkenyl groups or substituted or unsubstituted alkynyl groups, and therefore can effectively assist in the formation of an SEI layer as a crosslinker, resulting in the formation of a stronger SEI layer. The formation of such a stable SEI layer can extend the life of the electrode or effectively reduce battery swelling caused by electrolyte decomposition.

[0139] According to the present invention, in the formula IV, R″ is specifically an unsubstituted C2-C 10 or unsubstituted C2-C 10or an unsubstituted C2-C6 alkynyl group, more particularly an unsubstituted C2-C6 alkenyl group; or an unsubstituted C2-C6 alkynyl group, more particularly an unsubstituted C2-C5 alkenyl group; or an unsubstituted C2-C5 alkynyl group.

[0140] According to the present invention, the compound represented by the formula IV may be one or more compounds selected from the compounds represented by the following formulas IV-a to IV-c.

[0141] [ka]

[0142] [ka]

[0143] [ka]

[0144] 5) Compound represented by chemical formula V The compound represented by Formula V has two or more substituted or unsubstituted alkenyl groups or substituted or unsubstituted alkynyl groups, and therefore can effectively assist in the formation of an SEI layer as a crosslinker, resulting in the formation of a stronger SEI layer. The formation of such a stable SEI layer can extend the life of the electrode or effectively reduce battery swelling caused by electrolyte decomposition.

[0145] According to the present invention, in the formula V, R' is specifically selected from the group consisting of hydrogen, unsubstituted C1-C 10or an unsubstituted C1-C6 alkyl group, more specifically, each independently hydrogen; or an unsubstituted C1-C5 alkyl group.

[0146] According to the present invention, in the formula V, R″ is specifically an unsubstituted C2-C 10 or unsubstituted C2-C 10 or an unsubstituted C2-C6 alkynyl group, more particularly an unsubstituted C2-C6 alkenyl group; or an unsubstituted C2-C6 alkynyl group, more particularly an unsubstituted C2-C5 alkenyl group; or an unsubstituted C2-C5 alkynyl group.

[0147] According to the present invention, in the chemical formula V, R d and R e are specifically each independently hydrogen; unsubstituted C-C 10 or an unsubstituted siloxane group, more specifically, each independently may be hydrogen; an unsubstituted C1-C6 alkyl group; a siloxane group and / or a siloxane group substituted with a silane group; or an unsubstituted siloxane group, more specifically, each independently may be hydrogen; an unsubstituted C1-C5 alkyl group; a siloxane group and / or a siloxane group substituted with a silane group; or an unsubstituted siloxane group. d and R e When both of R and R are siloxane groups, R d and R e may be linked to each other to form a ring consisting of siloxane bonds.

[0148] According to the present invention, the compound represented by formula V may be one or more compounds selected from the compounds represented by formulas Va and Vb below.

[0149] [ka]

[0150] [ka]

[0151] When the compound represented by Formula I and one or more compounds selected from the compounds represented by Formulas II to V are both contained in a nonaqueous electrolyte, the weight ratio (A:B) of the compound represented by Formula I (A) to the one or more compounds selected from the compounds represented by Formulas II to V (B) may be 1 to 100:1, specifically 1 to 50:1, 1 to 40:1, 1 to 30:1, 1 to 20:1, or 1 to 10:1, or more specifically 1 to 9:1, 1 to 8:1, 1 to 7:1, 1 to 6:1, 1 to 5:1, 1 to 4:1, 1 to 3:1, or 1 to 2:1. In this case, the compound represented by Formula I is more abundant than the compounds represented by Formulas II to V, which act as crosslinkers, and can efficiently form crosslinks, resulting in the formation of an SEI layer with strong mechanical rigidity and improved battery stability. In this case, the non-aqueous electrolyte may contain the compound represented by Formula I in an amount of 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, relative to 100 parts by weight of the non-aqueous electrolyte. Also, the non-aqueous electrolyte may contain one or more compounds selected from the compounds represented by Formulas II to 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, relative to 100 parts by weight of the non-aqueous electrolyte. In this case, when the nonaqueous electrolyte is applied to a lithium metal battery, the SEI layer derived from the compound represented by Chemical Formula I and one or more compounds selected from the compounds represented by Chemical Formula II and Chemical Formula V has an appropriate thickness to allow smooth movement of lithium ions and has strong mechanical rigidity, thereby improving stability, preventing an increase in the internal resistance of the lithium metal battery, and preventing a decrease in battery capacity.

[0152] 6) Organic Solvents The organic solvent is a non-aqueous solvent commonly used in lithium metal batteries, and is not limited as long as it can minimize decomposition due to oxidation reactions during the charge / discharge process of the lithium metal battery and can exhibit desired properties together with the compounds represented by Chemical Formulas I to V.

[0153] The organic solvent may be, for example, but is not limited to, a linear or cyclic carbonate, a linear or cyclic ester, an ether, a glyme, a nitrile (acetonitrile, SN, etc.), etc. As the organic solvent, a carbonate-based electrolyte solvent containing a carbonate compound such as a cyclic carbonate, a linear carbonate, or a mixture thereof can be used.

[0154] On the other hand, specific examples of the cyclic carbonate compound include 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 are not limited to these.

[0155] Specific examples of the linear carbonate compound include, but are not limited to, dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate, and ethyl propyl carbonate.

[0156] Specific examples of the linear ester compound include, but are not limited to, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate.

[0157] Specific examples of the cyclic ester compound include, but are not limited to, γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0158] Specific examples of the ether solvent include, but are not limited to, 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).

[0159] The glyme-based solvent has a higher dielectric constant and lower surface tension than linear carbonate-based organic solvents and is less reactive with metals. Examples of the glyme-based solvent include, but are not limited to, dimethoxyethane (glyme, DME), diethoxyethane, diglyme, triglyme, and tetraglyme (TEGDME).

[0160] Specific examples of the nitrile solvent include, but are not limited to, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile.

[0161] On the other hand, the cyclic carbonate organic solvents ethylene carbonate and propylene carbonate are preferred because they are high-viscosity organic solvents with high dielectric constants that easily dissociate lithium salts in the electrolyte solution, and are more preferred when such cyclic carbonates are mixed with low-viscosity, low-dielectric-constant linear carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate in an appropriate ratio, since this makes it possible to produce an electrolyte solution with high electrical conductivity. In this case, the cyclic carbonate and linear carbonate may be mixed in a volume ratio of 2:8 to 4:6.

[0162] 7) Lithium salts The lithium salt is used as an electrolyte salt in a lithium metal battery and serves as a medium for ion transfer. Typically, the lithium salt includes one or more compounds selected from LiPF, LiBF, LiSbF, LiAsF, LiClO, LiN(CFSO), LiN(CFSO), CFSOLi, LiC(CFSO), LiCBO, LiTFSI, LiFSI, and LiClO, preferably, but not limited to, LiPF. Meanwhile, the lithium salt may be used alone or in combination of two or more, as needed.

[0163] According to the present invention, the lithium salt may be contained in the non-aqueous electrolyte at a concentration of 0.5 M to 5 M, preferably 0.5 M to 4 M. When the lithium salt concentration is within the above range, the concentration of lithium ions in the electrolyte is appropriate, facilitating smooth charging and discharging of the battery, and the viscosity of the electrolyte is appropriate, providing excellent wetting within the battery, thereby improving battery performance.

[0164] 8) Other electrolyte additives The non-aqueous electrolyte may further contain other electrolyte additives.

[0165] The other electrolyte additives are known electrolyte additives that can be further added to the non-aqueous electrolyte solution of the present invention, and examples thereof include 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 (1,3,5-tricyanobenzene, tetracyanoquinodimethane, pyrocarbonate, cyclohexylbenzene, propane sultone, succinonitrile, adiponitrile, ethylene sulfate, propene sultone, fluoroethylene carbonate, LiPO2F2, LiODFB (Lithium difluorooxalatoborate), LiBOB (Lithium bis-(oxalato)borate), TMSPa (3-trimethoxysilanyl-propyl-N-aniline), TMSPi (Tris(trimethylsilyl)Phosphite), 12-crown-4, 15-crown-5, 18-crown-6, aza-ethers, boranes, borates, boronates, ferrocene, and derivatives thereof, LiBF4, etc.

[0166] 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.

[0167] The lithium metal battery of the present invention can be manufactured by a conventional method known in the art, for example, by forming an electrode assembly having a positive electrode, a negative electrode, and a separator interposed therebetween, inserting the electrode assembly into a battery case, and injecting the nonaqueous electrolyte solution according to the present invention into the battery case.

[0168] The external shape of the lithium metal battery of the present invention is not particularly limited, and may be a cylindrical shape using a can, a square shape, a pouch shape, a coin shape, or the like.

[0169] According to the present invention, there is provided a battery module including the lithium metal battery as a unit cell, and a battery pack including the same. The battery module and battery pack include the lithium metal battery having high capacity, high rate characteristics, and high cycle characteristics, and can be used as a power source for medium to large devices selected from the group consisting of electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and power storage systems.

[0170] The present invention will be described in more detail below with reference to specific examples. However, the following examples are merely illustrative for understanding the present invention and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the present description and technical concept, and it goes without saying that such changes and modifications fall within the scope of the appended claims.

[0171] Synthesis Example Synthesis Example 1. Preparation of Compound of Formula Ia A two-neck round-bottom flask was charged with 3.5 equivalents of 2,2,2-trifluoroethanol, then connected to a dropping funnel and reflux condenser. The round-bottom flask was placed in an oil bath and heated to 50°C. While flowing with nitrogen, 1 equivalent of trichlorovinylsilane was slowly added dropwise through the dropping funnel over 1 hour. After the addition was completed, the reaction mixture was refluxed at 70°C while flowing with nitrogen, reacted overnight, cooled to room temperature, and the pH was checked. If the pH was below 7, it was neutralized with triethylamine (TEA), and the salt produced during this process was filtered. The remaining reactants and by-products were removed under reduced pressure at room temperature, followed by vacuum distillation at 60°C to obtain the compound represented by Formula Ia:

[0172] [ka]

[0173] Compounds of formula Ia 1 The H-NMR data is as follows: 1 H-NMR(400MHz, CDCl3) δ(ppm): 6.34(1H, dd), 6.18(1H, dd), 5.85(1H, dd), 4.12(6H, q)

[0174] Synthesis Example 2: Preparation of compound represented by chemical formula II-a A two-neck round-bottom flask was charged with 2.5 equivalents of 2,2,2-trifluoroethanol, and then connected to a dropping funnel and reflux condenser. The round-bottom flask was placed in an oil bath and heated to 50°C. While flowing with nitrogen, 1 equivalent of dichlorodivinylsilane was slowly added dropwise through the dropping funnel over 1 hour. After the addition was completed, the reaction mixture was refluxed at 70°C while flowing with nitrogen, reacted overnight, cooled to room temperature, and the pH was checked. If the pH was below 7, it was neutralized with triethylamine (TEA), and the salt produced during this process was filtered. The remaining reactants and by-products were removed under reduced pressure at room temperature, followed by vacuum distillation at 55°C to obtain the compound represented by Formula II-a.

[0175] [ka]

[0176] Compounds of formula II-a 1 The H-NMR data is as follows: 1 H-NMR(400MHz, CDCl3) δ(ppm): 6.32(2H, dd), 6.14(2H, dd), 5.84(2H, dd), 4.23(4H, q)

[0177] Synthesis Example 3: Preparation of Compound Represented by Chemical Formula III-b Under a nitrogen atmosphere and ice bath, 1 equivalent of dichlorodimethylsilane was slowly added dropwise over 1 hour to a Schlenk round-bottom flask containing 2.2 equivalents of allylmagensium bromide (1M in ether). After the addition was completed, the reaction was allowed to proceed overnight at room temperature. Five equivalents of saturated aqueous NH4Cl solution were added dropwise to the flask to terminate the reaction. The aqueous solution was separated and removed, and the resulting organic layer was dried over CaCl2, and the precipitate was removed by filtration. Residual reactants and by-products were removed under reduced pressure at room temperature, followed by vacuum distillation at 80°C to obtain the compound represented by the following chemical formula III-b.

[0178] [ka]

[0179] Compounds of formula III-b 1 The H-NMR data is as follows: 1 H-NMR(400MHz, CDCl3) δ(ppm): 5.77(2H, m), 4.85(4H, m), 1.53(4H, d), 0.00(6H, s)

[0180] Examples and Comparative Examples Example 1-1 (Production of non-aqueous electrolyte) A non-aqueous electrolyte solution was prepared by adding 1 g of the compound of 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 LiPF6 was dissolved.

[0181] (Lithium Metal Symmetric Cell Manufacturing) A lithium metal foil having a thickness of 200 μm was used for the negative electrode and the positive electrode. An electrode assembly was fabricated in an argon atmosphere glove box by interposing a porous polypropylene separator between the negative electrode and the positive electrode, and then the assembly was placed in a battery case, and the non-aqueous electrolyte was injected and sealed to fabricate a lithium metal symmetric cell in the form of a coin cell.

[0182] Example 1-2 A non-aqueous electrolyte solution was prepared by adding 0.5 g of the compound represented by Formula Ia and 0.5 g of the compound represented by Formula II-a to 99 g of an organic solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 1:2 volume ratio) containing 1.0 M LiPF6. A lithium metal symmetric cell was prepared in the same manner as in Example 1-1, except that the non-aqueous electrolyte solution prepared in this manner was used.

[0183] Examples 1-3 A non-aqueous electrolyte solution was prepared by adding 0.5 g of the compound represented by Formula Ia and 0.5 g of the compound represented by Formula III-b to 99 g of an organic solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 1:2 volume ratio) containing 1.0 M LiPF6. A lithium metal symmetric cell was prepared in the same manner as in Example 1-1, except that the non-aqueous electrolyte solution prepared in this manner was used.

[0184] Examples 1-4 A non-aqueous electrolyte solution was prepared by adding 0.5 g of the compound represented by formula Ia and 0.5 g of the compound represented by formula IV-a (Sigma-Aldrich) to 99 g of an organic solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 1:2 volume ratio) containing 1.0 M LiPF6. A lithium metal symmetric cell was prepared in the same manner as in Example 1-1, except that the non-aqueous electrolyte solution prepared in this manner was used.

[0185] Examples 1-5 A non-aqueous electrolyte solution was prepared by adding 0.5 g of the compound represented by formula Ia and 0.5 g of the 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 solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 1:2 volume ratio) containing 1.0 M LiPF. A lithium metal symmetric cell was prepared in the same manner as in Example 1-1, except that the non-aqueous electrolyte solution prepared in this manner was used.

[0186] Comparative Example 1-1 A lithium metal symmetric cell was fabricated 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 in Example 1-1.

[0187] Comparative Example 1-2 A non-aqueous electrolyte was prepared by adding 1 g of 1,3-propane sultone (Sigma-Aldrich) to 99 g of an organic solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 1:2 volume ratio) containing 1.0 M LiPF6. A lithium metal symmetric cell was fabricated in the same manner as in Example 1-1, except that the non-aqueous electrolyte was used.

[0188] Comparative Examples 1-3 A non-aqueous electrolyte was prepared by adding 1 g of TEOS (Tetraethoxysilane) (Sigma-Aldrich) to 99 g of an organic solution (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 in this manner was used.

[0189] [Table 1]

[0190] Example 2-1 (Production of non-aqueous electrolyte) A non-aqueous electrolyte solution was prepared by adding 1 g of the compound of 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 LiPF6 was dissolved.

[0191] (Lithium metal battery manufacturing) Cathode active material (LiNi 0.8 Co 0.1 Mn 0.1 A cathode active material slurry was prepared by adding 02, a conductive material (carbon black), and a binder (polyvinylidene fluoride) to N-methyl-2-pyrrolidone (NMP) in a weight ratio of 90:5:5. The cathode active material slurry was coated on both sides of a 15 μm-thick cathode current collector (aluminum thin film) to a thickness of 59 μm, dried, and rolled using a roll press to prepare a cathode (width: 12 mm, length: 12 mm, thickness: 74 μm).

[0192] A lithium metal foil having a thickness of 200 μm was used as the negative electrode. An electrode assembly was fabricated by interposing a porous polypropylene separator between the negative electrode and the positive electrode in a glove box under an argon atmosphere, and then the assembly was placed in a battery case, and the non-aqueous electrolyte solution was injected and sealed to fabricate a coin cell type lithium metal battery.

[0193] Example 2-2 A non-aqueous electrolyte solution was prepared by adding 0.5 g of the compound represented by Formula Ia and 0.5 g of the compound represented by Formula II-a to 99 g of an organic solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 1:2 volume ratio) containing 1.0 M LiPF6. A lithium metal battery was fabricated in the same manner as in Example 2-1, except that the non-aqueous electrolyte solution prepared in this manner was used.

[0194] Example 2-3 A non-aqueous electrolyte solution was prepared by adding 0.5 g of the compound represented by Formula Ia and 0.5 g of the compound represented by Formula III-b to 99 g of an organic solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 1:2 volume ratio) containing 1.0 M LiPF6. A lithium metal battery was fabricated in the same manner as in Example 2-1, except that the non-aqueous electrolyte solution prepared in this manner was used.

[0195] Examples 2-4 A non-aqueous electrolyte solution was prepared by adding 0.5 g of the compound represented by Formula Ia and 0.5 g of the compound represented by Formula IV-a to 99 g of an organic solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 1:2 volume ratio) containing 1.0 M LiPF. A lithium metal battery was fabricated in the same manner as in Example 2-1, except that the non-aqueous electrolyte solution prepared in this manner was used.

[0196] Examples 2-5 A non-aqueous electrolyte solution was prepared by adding 0.5 g of the compound represented by formula Ia and 0.5 g of the 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 solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 1:2 volume ratio) containing 1.0 M LiPF. A lithium metal battery was fabricated in the same manner as in Example 2-1, except that the non-aqueous electrolyte solution prepared in this manner was used.

[0197] Comparative Example 2-1 A lithium metal battery was fabricated 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 as the non-aqueous electrolyte instead of the non-aqueous electrolyte in Example 2-1.

[0198] Comparative Example 2-2 A non-aqueous electrolyte was prepared by adding 1 g of 1,3-propane sultone (Sigma-Aldrich) to 99 g of an organic solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 1:2 volume ratio) containing 1.0 M LiPF6. A lithium metal battery was fabricated in the same manner as in Example 2-1, except that the non-aqueous electrolyte was used.

[0199] Comparative Example 2-3 A non-aqueous electrolyte solution was prepared by adding 1 g of TEOS (Tetraethoxysilane) (Sigma-Aldrich) to 99 g of an organic solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 1:2 volume ratio) in which 1.0 M LiPF6 was dissolved. A lithium metal battery was fabricated in the same manner as in Example 2-1, except that the non-aqueous electrolyte solution prepared in this manner was used.

[0200] [Table 2]

[0201] Experimental Example Experimental Example 1: Evaluation of Lithium Metal Symmetric Cell Characteristics The lithium metal symmetric cells produced in Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-3 were charged and discharged at 0.2 mA / cm at 25°C in a charger / discharger. 2 The activation process was carried out by charging the battery to the cutoff point for 1 hour at a current density of 1.0 mA / cm and discharging it for 1 hour, with the initial discharge process being repeated three times. 2 The initial charge-discharge process was performed 500 times, with one cycle consisting of charging to the cutoff point at a current density of 0.2 mA / cm and discharging for 1 hour. 2 The overvoltage that occurs in the first cycle (overvoltage at activation) when the current density is 1.0 mA / cm 2 The overvoltages occurring at the 1st, 100th, 200th, and 300th cycles are shown in Table 3 below.

[0202] [Table 3]

[0203] As shown in Table 3 above, in Examples 1-1 to 1-5, the voltage was maintained lower than in Comparative Examples 1-1 to 1-3, and the life characteristics were improved.

[0204] In Examples 1-1 to 1-5, an SEI layer with high structural flexibility and stability was formed on the lithium metal foil, which is believed to have led to uniform plating / peeling, improving the life and stability of the lithium metal battery.In contrast, in Comparative Examples 1-1 to 1-3, it was confirmed that plating / peeling occurred unevenly on the lithium metal foil or on the lithium metal foil.

[0205] Experimental example 2: Evaluation of cycle characteristics The lithium metal batteries of Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-3 were charged at 25°C under constant current / constant voltage conditions at a 0.1 C rate to 4.3 V, 0.05 C cutoff, and discharged to 3.0 V for two cycles. Then, 100 cycles were performed under constant current / constant voltage conditions at a 1.0 C rate to 4.3 V, 0.05 C cutoff, and discharged to 3.0 V for 100 cycles. The capacity after one cycle and the discharge capacity after 100 cycles were measured, and the discharge capacity retention rate (discharge capacity after 100 cycles / discharge capacity after one cycle × 100) was calculated and shown in Table 4 below.

[0206] [Table 4]

[0207] As shown in Table 4 above, Examples 2-1 to 2-5 had improved discharge capacity retention rates at the 100th cycle compared to Comparative Examples 2-1 to 2-3.

[0208] These characteristics are due to the fact that the silane-based additive contained in the nonaqueous electrolyte solutions of Examples 2-1 to 2-5 efficiently forms a highly stable and robust SEI layer. Specifically, the silane-based additive represented by Chemical Formula I forms a covalent bond ([Li]-O-Si-O-) with the electrode, thereby forming an SEI layer that is not significantly affected by volume change, i.e., has excellent mechanical rigidity. As a result, 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, which is thought to have resolved the stability problem caused by the formation of lithium dendrites during charge and discharge.

[0209] In addition, the silane-based additive represented by chemical formula I contains fluorine element, and serves as a source of fluorine anions during the reduction / oxidation decomposition reaction, thereby helping to form a LiF-based SEI layer, which is a stable inorganic compound contained in the SEI layer.

[0210] This is because the silane additive represented by Chemical Formula I contains an alkenyl group and forms a C—C bond through a reduction / oxidation decomposition reaction, forming a polymeric SEI layer.

Claims

1. A positive electrode and a lithium metal anode; a separator interposed between the positive electrode and the lithium metal negative electrode; A lithium metal battery comprising an organic solvent, a lithium salt, and a non-aqueous electrolyte solution comprising a compound represented by the following chemical formula I: 【Chemical 1】 (wherein, in the above chemical formula I, R ａ is C substituted with one or more fluorine atoms １ -C １０ is an alkyl group of the formula R ｂ are each independently a C which is substituted or not substituted with one or more fluorine atoms; １ -C １０ is an alkyl group of the formula R' is independently hydrogen; substituted or unsubstituted C １ -C １０ or a substituted or unsubstituted C １ -C １０ is a heteroalkyl group of the formula R″ is a substituted or unsubstituted C ２ -C １０ an alkenyl group of the formula: ２ -C １０ is an alkynyl group of the formula:

2. 2. The lithium metal battery of claim 1, wherein the non-aqueous electrolyte further comprises at least one compound selected from the group consisting of compounds represented by the following formulas II to V: 【Chemistry 2】 [Chemical formula IV] Si (R'') ４ 【Chemistry 3】 (In the above chemical formulas II to V, R ｂ are each independently a C which is substituted or not substituted with one or more fluorine atoms; １ -C １０ is an alkyl group of the formula R ｃ are each independently substituted or unsubstituted C １ -C １０ is an alkyl group of the formula R' is independently hydrogen; substituted or unsubstituted C １ -C １０ or a substituted or unsubstituted C １ -C １０ is a heteroalkyl group of the formula R″ is a substituted or unsubstituted C ２ -C １０ an alkenyl group of the formula: ２ -C １０ is an alkynyl group of the formula R ｄ and R ｅ are each independently hydrogen; substituted or unsubstituted C １ -C １０ an alkyl group of the formula: １ -C １０ or a substituted or unsubstituted siloxane group, R ｄ and R ｅ When both of R ｄ and R ｅ may be linked to each other to form a ring consisting of siloxane bonds, n is 2 or 3.

3. 3. The lithium metal battery of claim 2, wherein the compound represented by Formula I is one or more compounds selected from the compounds represented by Formulas Ia to If: 【Chemistry 4】 【Chemistry 5】

4. The lithium metal battery of claim 2, wherein the compound represented by Formula II is one or more compounds selected from the compounds represented by Formulas II-a to II-f: 【Chemistry 6】 【Chemistry 7】

5. 3. The lithium metal battery of claim 2, wherein the compound represented by formula III is one or more compounds selected from the group consisting of compounds represented by formulas III-a to III-o: 【Chemistry 8】 【Chemistry 9】 【Chemistry 10】 【Chemistry 11】

6. The lithium metal battery of claim 2, wherein the compound represented by formula IV is one or more compounds selected from the group consisting of compounds represented by formulas IV-a to IV-c: 【Chemistry 12】

7. 3. The lithium metal battery according to claim 2, wherein the compound represented by the chemical formula V is one or more compounds selected from the compounds represented by the following chemical formulas Va and Vb: 【Chemistry 13】

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