Additive for non-aqueous electrolyte and lithium secondary battery containing the same

Abstract

The present invention relates to a novel additive for non-aqueous electrolytes and a lithium secondary battery containing the same. The additive for non-aqueous electrolytes includes an ionic compound represented by Chemical Formula 1, which forms a film on the electrode surface during activation of the secondary battery, thereby preventing a large amount of gas from being generated under high temperature conditions, and can prevent a decrease in OCV and a decrease in capacity retention rate of the cell due to metal ions being eluted from the electrode, thereby effectively improving the durability, performance, and high temperature safety of the battery.

Description

Technical Field

[0001] The present invention relates to a novel additive for non-aqueous electrolytes and a lithium secondary battery containing the same.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0033306 filed on March 17, 2022, and all contents disclosed in the literature of the Korean patent application are included as part of this specification.

Background Art

[0003] In recent years, secondary batteries have been widely applied not only to small devices such as portable electronic devices but also to medium and large devices such as battery packs or power storage devices for hybrid vehicles and electric vehicles. Such secondary batteries include non-aqueous electrolyte batteries such as lithium-ion batteries, lithium batteries, lithium-ion capacitors, and sodium-ion batteries.

[0004] Among such non-aqueous electrolyte batteries, a lithium-ion battery is used by injecting an electrolyte into a battery cell including a positive electrode containing a positive electrode active material capable of intercalating and deintercalating lithium and a negative electrode containing a negative electrode active material capable of intercalating and deintercalating lithium. In particular, the electrolyte uses an organic solvent in which a lithium salt is dissolved, and is important for determining the stability and performance of the lithium secondary battery.

[0005] For example, generally, LiPF most commonly used as the lithium salt of the electrolyte 6 reacts with the electrolyte solvent to generate HF while promoting depletion of the solvent. The HF thus generated not only generates a large amount of gas under high-temperature conditions but also can elute metal ions. When the eluted metal ions are generated in a form deposited on the surface of the negative electrode, it causes problems such as an increase in the negative electrode potential and a decrease in the OCV of the cell, thus degrading not only the performance of the battery but also its lifespan and high-temperature safety.

Summary of the Invention

Problems to be Solved by the Invention

[0006] Therefore, an object of the present invention is to form a film on the electrode surface to prevent direct contact between the positive electrode and the electrolyte, prevent direct contact with HF, PF, etc., reduce oxidative decomposition of the electrolyte, and suppress gas generation. And while improving the metal ion deposition phenomenon from the positive electrode to improve the capacity retention rate, it is to provide the development of a technology capable of preventing a decrease in the OCV of the battery. 5

Means for Solving the Problems

[0007] In order to solve the above-described problems, the present invention provides, in one embodiment, an electrolyte additive for a secondary battery containing a compound represented by the following Chemical Formula 1.

[0008]

Chem.

[0009] In the above Chemical Formula 1, R 1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, R 2 is an arylene group having 6 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a heteroarylene group having 5 to 10 carbon atoms containing one or more heteroatoms of N, S, and O, or a heteroarylene group having 5 to 10 carbon atoms containing one or more heteroatoms of N, S, and O. An aryloxy group, R 3 is a fluoro group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or

Chem.

Chem.

[0010] Specifically, the above R 1 is hydrogen or a methyl group, R 2 is a phenylene group, naphthalene group, anthracenylene group, biphenylene group, phenyleneoxy group, pyridinylene group, thiophenylene group, dioxolene group or dithiolene group, R 3 is a fluoro group, methyl group, ethyl group, propyl group, methoxy group, ethoxy group,

Chemical formula

Chemical formula

[0011] More specifically, the compound represented by the above Chemical formula 1 may be any one or more of the following <Structural formula 1> to <Structural formula 48>.

[0012]

Chemical formula

[0013]

Chemical formula

[0014]

Chemical formula

[0015] [Chemical formula]

[0016] Further, in one embodiment, the present invention provides an electrolyte composition for a secondary battery, which includes a non-aqueous organic solvent, a lithium salt, and a compound represented by the following Chemical Formula 1.

[0017] [Chemical formula]

[0018] In the above Chemical Formula 1, R 1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, R 2 includes an arylene group having 6 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a heteroarylene group having 5 to 10 carbon atoms containing one or more heteroatoms among N, S, and O, or a heteroaryloxy group having 5 to 10 carbon atoms containing one or more heteroatoms among N, S, and O, R 3 is a fluoro group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or [Chemical formula] and one or more of the hydrogen atoms included in the above alkyl group, alkoxy group, and [Chemical formula] may be substituted with a fluorine atom, X is an oxygen atom (O) or -NR 4 , R 4 is hydrogen or an alkyl group having 1 to 4 carbon atoms, M includes one or more selected from the group consisting of lithium, sodium, potassium, tetraalkylammonium having 1 to 4 carbon atoms, and tetraalkylphosphonium having 1 to 4 carbon atoms, l is an integer of 1 to 6, and m is an integer of 2 to 20.

[0019] At this time, the compound represented by the above chemical formula 1 may be contained in an amount of 0.01 to 3% by weight based on the total weight of the electrolytic solution composition.

[0020] In addition, the lithium salt is LiCl, LiBr, LiI, LiClO 4 , LiBF 4 , LiB 10 Cl 10 , LiPF 6 , LiCF 3 SO 3 , LiCF 3 CO 2 , LiAsF 6 , LiSbF 6 , LiAlCl 4 , CH 3 SO 3 Li, (CF 3 SO 2 ) 2 NLi and (FSO 2 ) 2 NLi may include one or more selected from the group consisting of.

[0021] In addition, the non-aqueous organic solvent may include N-methyl-2-pyrrolidinone, ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfuran (franc), 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, triphosphate ester, trimethoxymethane, dioxolane derivative, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ether, methyl propionate and ethyl propionate.

[0022] Furthermore, in one embodiment, the present invention provides a lithium secondary battery including a positive electrode containing one or more positive electrode active materials of lithium metal oxides represented by the following Chemical Formula 2 and Chemical Formula 3, a negative electrode containing a negative electrode active material, and a separator interposed between the positive electrode and the negative electrode, and an electrolytic solution composition according to the present invention.

[0023] [Chemical Formula 2] Li x [Ni y Co z Mn w M 1 v O 2

[0024] [Chemical Formula 3] LiM 2 p Mn (2-p) O 4

[0025] In Chemical Formula 2 and Chemical Formula 3 above, M 1 is one or more elements selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and x, y, z, w, and v are 1.0 ≦ x ≦ 1.30, 0.5 ≦ y < 1, 0 < z ≦ 0.3, 0 < w ≦ 0.3, 0 ≦ v ≦ 0.1, respectively, y + z + w + v = 1, M 2 is Ni, Co, or Fe, and p is 0.05 ≦ p ≦ 0.6.

[0026] At this time, the positive electrode active material is LiNi 0.8 Co 0.1 Mn 0.1 O 2 、LiNi 0.6 Co 0.2 Mn 0.2 O 2 、LiNi 0.9 Co 0.05 Mn 0.05 O 2 、LiNi 0.6 Co 0.2 Mn 0.1 Al0.1 O 2 、 LiNi 0.6 Co 0.2 Mn 0.15 Al 0.05 O 2 、 LiNi 0.7 Co 0.1 Mn 0.1 Al 0.1 O 2 、 LiNi 0.5 Mn 1.5 O 4 may include one or more selected from the group consisting of.

[0027] Also, the negative electrode active material is composed of a carbon material and a silicon material, and the silicon material may include one or more of silicon (Si), silicon carbide (SiC), and silicon oxide (SiO q , provided that 0.8 ≦ q ≦ 2.5).

[0028] Also, the silicon material may be contained in an amount of 1 to 20% by weight based on the total weight of the negative electrode active material.

Advantages of the Invention

[0029] The electrolyte additive according to the present invention can prevent a large amount of gas from being generated under high-temperature conditions by forming a film on the electrode surface during the activation of the secondary battery, and can effectively prevent the elution of metal ions from the electrode and the reduction of the OCV and the capacity retention rate of the cell. Therefore, the durability, performance, and high-temperature safety of the battery can be effectively improved.

Modes for Carrying Out the Invention

[0030] The present invention can be subjected to various modifications and can have various embodiments, so specific embodiments will be described in detail in the detailed description.

[0031] However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, or alternatives included in the spirit and technical scope of the present invention.

[0032] In the present invention, terms such as "comprising" and "having" are intended to specify the presence of the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should be understood not to preclude in advance the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0033] Also, in the present invention, when a part such as a layer, film, region, or plate is described as being "on" another part, this includes not only the case where it is directly on the other part but also the case where there is another part in between. Conversely, when a part such as a layer, film, region, or plate is described as being "under" another part, it includes not only the case where it is directly under the other part but also the case where there is another part in between. Also, in the present application, being "disposed on" can include not only the upper part but also the case of being disposed on the lower part.

[0034] Also, in the present invention, "comprising as a main component" can mean containing 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, or 95% by weight or more of a component defined with respect to the total weight. For example, "comprising graphite as a main component as the negative electrode active material" can mean containing 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, or 95% by weight or more of graphite with respect to the total weight of the negative electrode active material, and in some cases, it can also mean that the entire negative electrode active material consists of graphite and contains graphite at 100% by weight.

[0035] Hereinafter, the present invention will be described in more detail.

[0036] <Additive for Electrolyte of Secondary Battery> In one embodiment, the present invention provides an additive for an electrolyte of a secondary battery containing a compound represented by the following Chemical Formula 1.

[0037]

Chemical Formula

[0038] In the above Chemical Formula 1, R 1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, and R 2 is an arylene group having 6 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a heteroarylene group having 5 to 10 carbon atoms containing one or more heteroatoms among N, S, and O, or a heteroaryloxy group having 5 to 10 carbon atoms containing one or more heteroatoms among N, S, and O, and R 3 is a fluoro group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or

Chemical formula

Chemical formula

[0039] The electrolyte additive for a secondary battery according to the present invention includes an ionic compound having a parent nucleus structure bonded through a cyclic unsaturated hydrocarbon group having a (meth)acrylate group or a (meth)acrylamide group having a conjugated structure on one side centered on a sulfonylimide group as shown in Chemical Formula 1 above, or a cyclic unsaturated heterohydrocarbon group having a structure in which a heteroatom is introduced into the cyclic unsaturated hydrocarbon group. The compound includes a functional group having a conjugated structure or a structure in which a heteroatom is introduced into the cyclic unsaturated hydrocarbon group between the sulfonylimide group and the (meth)acrylate group or the (meth)acrylamide group as a linker, and can embody a conjugated structure from the sulfonylimide group to the (meth)acrylate or (meth)acrylamide group. Therefore, when the secondary battery including the compound is activated, an organic and / or inorganic film can be uniformly formed on the surface of the positive electrode and / or the negative electrode. That is, the electrolyte additive can be directly included in the organic and / or inorganic film formed on the surface of the positive electrode and / or the negative electrode in a single molecular form when the secondary battery is activated. Thereby, when the battery is exposed to a high temperature, decomposition of the electrolyte to generate gas can be suppressed, and at the same time, a decrease in the OCV of the battery generated at the positive electrode and a decrease in the capacity retention rate can be improved.

[0040] For this purpose, in the compound represented by Chemical Formula 1 above, R 1 is hydrogen, a methyl group, an ethyl group, or a propyl group, and R 2 is a phenylene group, a naphthalene group, an anthracenylene group, a biphenylene group, a phenyleneoxy group, a pyridinylene group, a thiophenylene group, a dioxolene group, or a dithiolene group, and R 3 is a fluoro group, a methyl group, an ethyl group, a propyl group, a methoxy group, an ethoxy group,

Chemical Formula

Chemical Formula

[0041] Specifically, R 1 is hydrogen or a methyl group, R 2 is a phenylene group, naphthalene group, anthracenylene group, biphenylene group, phenyleneoxy group, pyridinylene group, thiophenylene group, dioxolene group or dithiolene group, and R 3 is a fluoro group, methyl group, ethyl group, propyl group, methoxy group, ethoxy group,

Chemical formula

Chemical formula

[0042] As an example, the compound represented by the above Chemical formula 1 can be any one or more of the following <Structural formula 1> to <Structural formula 48>.

[0043]

Chemical formula

[0044]

Chemical formula

[0045]

Chemical formula

[0046]

Chem.

[0047] As described above, the electrolyte additive according to the present invention has a structure in which, on one side centered on a sulfonylimide group, a (meth)acrylate group or a (meth)acrylamide group is bonded via a cyclic unsaturated hydrocarbon group having a conjugated structure or a functional group having a structure in which a heteroatom is introduced into the cyclic unsaturated hydrocarbon group, and has a charge inside the molecule. The electrolyte additive having such a structure can directly participate in the solvation shell of lithium ions even at a low potential during the activation of the secondary battery, and can uniformly form a negatively charged property and / or an inorganic film by a reduction reaction on the surface of the negative electrode. At the same time, an inorganic film can be uniformly formed on the surface of the positive electrode by an oxidation reaction. The organic and / or inorganic film thus formed suppresses the decomposition of the electrolyte and the generation of gas when the battery is exposed to a high temperature, and can improve the OCV decrease phenomenon and the capacity decrease of the battery occurring at the positive electrode. Therefore, the deterioration of the secondary battery can be prevented.

[0048] <Electrolyte Composition for Lithium Secondary Battery> Further, in one embodiment, the present invention provides an electrolyte composition for a lithium secondary battery including a non-aqueous organic solvent, a lithium salt, and a compound represented by the following Chemical Formula 1.

[0049]

Chem.

[0050] In the above Chemical Formula 1, R 1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, and R 2contains an arylene group having 6 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a heteroarylene group having 5 to 10 carbon atoms containing one or more heteroatoms among N, S and O, or a heteroaryleneoxy group having 5 to 10 carbon atoms containing one or more heteroatoms among N, S and O, and R 3 is a fluoro group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or

Chemical formula

Chemical formula

[0051] The electrolyte composition for a lithium secondary battery according to the present invention is a liquid non-aqueous electrolyte composition, which has a configuration including a lithium salt and an electrolyte additive in a non-aqueous organic solvent. Here, the above electrolyte composition contains the compound represented by Chemical formula 1 as an electrolyte additive, includes the above-described electrolyte additive of the present invention, and directly participates in the solvation shell of lithium ions during activation of the battery containing the same, so that a negative charge property and / or an inorganic film can be uniformly formed by a reduction reaction on the surface of the negative electrode.

[0052] Therefore, in the compound represented by Chemical formula 1 above, R 1 is hydrogen, a methyl group, an ethyl group or a propyl group, R 2 is a phenylene group, a naphthalene group, an anthracenylene group, a biphenylene group, a phenyleneoxy group, a pyridinylene group, a thiophenylene group, a dioxolene group or a dithiolene group, R 3is a fluoro group, methyl group, ethyl group, propyl group, methoxy group, ethoxy group,

Chem.

Chem.

[0053] Specifically, R 1 is hydrogen or a methyl group, R 2 is a phenylene group, naphthalene group, anthracenylene group, biphenylene group, phenyleneoxy group, pyridinylene group, thiophenylene group, dioxolen group or dithiolene group, and R 3 is a fluoro group, methyl group, ethyl group, propyl group, methoxy group, ethoxy group,

Chem.

Chem.

[0054] In addition, the compound represented by the above Chemical Formula 1 can be contained in the electrolyte composition at a specific content. Specifically, the compound represented by the above Chemical Formula 1 can be contained at 0.01 to 5% by weight based on the total weight of the electrolyte composition. More specifically, it can be contained at 0.05 to 3% by weight or 1.0 to 2.5% by weight based on the total weight of the electrolyte composition. The present invention can prevent the viscosity of the electrolyte composition from increasing by using an excessive amount of the electrolyte additive outside the above-described range, and prevent the wettability with respect to the electrode and the separator from decreasing. Further, it can prevent the excessive amount of the electrolyte additive from inducing polymerization of itself in the electrolyte composition during battery activation, reducing the ionic conductivity of the electrolyte composition, and degrading battery performance. Also, the present invention can prevent the effect of the additive from being only slightly realized by using a trace amount of the electrolyte additive outside the above-described range.

[0055] On the other hand, the lithium salt used in the above electrolyte composition can be applied without particular limitation as long as it is used for non-aqueous electrolytes in the art. Specifically, the lithium salt is LiCl, LiBr, LiI, LiClO 4 , LiBF 4 , LiB 10 Cl 10 , LiPF 6 , LiCF 3 SO 3 , LiCF 3 CO 2 , LiAsF 6 , LiSbF 6 , LiAlCl 4 , CH 3 SO 3 Li, (CF 3 SO 2 ) 2 NLi, and (FSO 2 ) 2 NLi, and may contain one or more selected from the group consisting of.

[0056] There are no particular restrictions on the concentration of these lithium salts. However, the lower limit of the preferred concentration range is 0.5 mol / L or more, specifically 0.7 mol / L or more, and more specifically 0.9 mol / L or more. The upper limit of the preferred concentration range is 2.5 mol / L or less, specifically 2.0 mol / L or less, and more specifically 1.5 mol / L or less. When the concentration of the lithium salt is less than 0.5 mol / L, the ionic conductivity decreases, which may lead to a decrease in the cycle characteristics and output characteristics of the non-aqueous electrolyte battery. Also, when the concentration of the lithium salt exceeds 2.5 mol / L, the viscosity of the electrolyte for the non-aqueous electrolyte battery increases, which may also cause a decrease in ionic conductivity and may lead to a decrease in the cycle characteristics and output characteristics of the non-aqueous electrolyte battery.

[0057] Moreover, when a large amount of lithium salt is dissolved in a non-aqueous organic solvent at once, the liquid temperature may rise due to the heat of solution of the lithium salt. Thus, when the temperature of the non-aqueous organic solvent rises significantly due to the heat of solution of the lithium salt, in the case of a lithium salt containing fluorine, there is a risk that decomposition will be promoted and hydrogen fluoride (HF) will be generated. Hydrogen fluoride (HF) is not preferable because it causes deterioration of battery performance. Therefore, the temperature when dissolving the above lithium salt in a non-aqueous organic solvent is not particularly limited, but can be adjusted to -20 to 80 °C, specifically can be adjusted to 0 to 60 °C.

[0058] In addition, the non-aqueous organic solvent used in the above electrolyte composition can be applied without particular limitation as long as it is used in non-aqueous electrolytes in the art. Specifically, examples of the non-aqueous organic solvent include N-methyl-2-pyrrolidinone, ethylene carbonate (EC), propylene carbonate, butylene carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), gamma-butyrolactone, 1,2-dimethoxyethane (DME), tetrahydroxyfuran (franc), 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxymethane, dioxolane derivative, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ether, methyl propionate, ethyl propionate and other non-quantum organic solvents can be used.

[0059] In addition, the non-aqueous organic solvent used in the present invention may be used alone or in any combination and ratio by mixing two or more types according to the application. Among these, from the viewpoints of the electrochemical stability against oxidation-reduction and the chemical stability regarding the reaction with heat and solute, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, diethyl carbonate, dimethyl carbonate, and ethyl methyl carbonate are particularly preferable.

[0060] On the one hand, the above electrolytic solution composition may further contain an additive in addition to the basic components described above. As long as the gist of the present invention is not impaired, additives generally used in the non-aqueous electrolytic solution of the present invention may be added at any ratio. Specifically, compounds having an overcharge prevention effect, a negative electrode film formation effect, and a positive electrode protection effect such as cyclohexylbenzene, biphenyl, t-butylbenzene, vinylene carbonate, vinyl ethylene carbonate, difluoroanisole, fluoroethylene carbonate, propane sultone, succinonitrile, dimethylvinylene carbonate, etc. can be mentioned. Further, in the same manner as when used in a non-aqueous electrolytic solution battery called a lithium polymer battery, it is also possible to solidify the electrolytic solution for a non-aqueous electrolytic solution battery with a gelling agent or a crosslinked polymer and use it.

[0061] <Lithium secondary battery> Furthermore, in one embodiment of the present invention, a positive electrode containing one or more positive electrode active materials of lithium metal oxides represented by the following Chemical Formula 2 and Chemical Formula 3, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and an electrolytic solution composition according to the present invention are provided. A lithium secondary battery is provided.

[0062] [Chemical Formula 2] Li x [Ni y Co z Mn w M 1 v O 2

[0063] [Chemical Formula 3] LiM 2 p Mn (2-p) O 4

[0064] In the above Chemical Formula 2 and Chemical Formula 3, M 1is one or more elements selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, where x, y, z, w, and v are 1.0 ≦ x ≦ 1.30, 0.5 ≦ y < 1, 0 < z ≦ 0.3, 0 < w ≦ 0.3, 0 ≦ v ≦ 0.1 respectively, y + z + w + v = 1, and M 2 is Ni, Co, or Fe, and p is 0.05 ≦ p ≦ 0.6.

[0065] The lithium secondary battery according to the present invention includes a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, a separator interposed between the positive electrode and the negative electrode, and the lithium salt-containing non-aqueous electrolyte composition of the present invention described above.

[0066] Specifically, the positive electrode includes a positive electrode composite layer manufactured by applying, drying, and pressing a positive electrode active material on a positive electrode current collector, and may further selectively include a conductive material, a binder, other additives, etc. as necessary.

[0067] Here, the positive electrode active material is a substance that can undergo an electrochemical reaction on the positive electrode current collector, and may include one or more of the lithium metal oxides represented by Chemical Formula 2 and Chemical Formula 3 above that are capable of reversible intercalation and deintercalation of lithium ions.

[0068] The lithium metal oxides represented by Chemical Formula 2 and Chemical Formula 3 above are substances that contain high contents of nickel (Ni) and manganese (Mn) respectively, and when used as a positive electrode active material, have the advantage of being able to stably supply electricity with high capacity and / or high voltage. Also, when activating the secondary battery, a charging potential of 4.0 V or higher is required to form a film on the surface of the positive electrode and / or the negative electrode. However, unlike conventional positive electrode active materials such as iron phosphate compounds whose charging potential is less than about 4.0 V, the above lithium metal oxides have a high charging potential of about 4.0 V or higher, so the formation of a film on the electrode may be easy.

[0069] At this time, examples of the lithium metal oxide represented by the above chemical formula 2 include LiNi 0.8 Co 0.1 Mn 0.1 O 2 、LiNi 0.6 Co 0.2 Mn 0.2 O 2 、LiNi 0.9 Co 0.05 Mn 0.05 O 2 、LiNi 0.6 Co 0.2 Mn 0.1 Al 0.1 O 2 、LiNi 0.6 Co 0.2 Mn 0.15 Al 0.05 O 2 、LiNi 0.7 Co 0.1 Mn 0.1 Al 0.1 O 2 and the like. Examples of the lithium metal oxide represented by the above chemical formula 3 include LiNi 0.7 Mn 1.3 O 4 、LiNi 0.5 Mn 1.5 O 4 、LiNi 0.3 Mn 1.7 O 4 and the like, and these can be used alone or in combination.

[0070] In addition, for the above positive electrode, as the positive electrode current collector, one having high conductivity without inducing a chemical change in the battery can be used. For example, stainless steel, aluminum, nickel, titanium, fired carbon, etc. can be used, and in the case of aluminum or stainless steel, those surface-treated with carbon, nickel, titanium, silver, etc. can also be used. Further, the average thickness of the current collector can be preferably applied in the range of 3 to 500 μm in consideration of the conductivity and the total thickness of the positive electrode to be manufactured.

[0071] Also, similar to the positive electrode, the negative electrode includes a negative electrode composite material layer manufactured by applying, drying, and pressing a negative electrode active material onto a negative electrode current collector, and may further selectively include a conductive material, a binder, other additives, etc. as necessary.

[0072] The negative electrode active material may include a carbon material and a silicon material. Specifically, the carbon material means a material mainly composed of carbon atoms. Such carbon materials may include one or more selected from the group consisting of natural graphite, artificial graphite, expanded graphite, graphitization-resistant carbon, carbon black, acetylene black, and ketjen black. Also, the silicon material means a material mainly composed of silicon atoms. Such silicon materials may include silicon (Si), silicon carbide (SiC), silicon monoxide (SiO), or silicon dioxide (SiO 2 ) alone or in combination. When silicon monoxide (SiO) and silicon dioxide (SiO 2 ) are uniformly mixed or compounded and included in the negative electrode composite material layer, they can be represented as silicon oxide (SiO q , provided that 0.8 ≦ q ≦ 2.5).

[0073] Also, the silicon material may be included in an amount of 1 to 20% by weight, specifically 3 to 10% by weight, 8 to 15% by weight, 13 to 18% by weight, or 2 to 8% by weight, based on the total weight of the negative electrode active material. The present invention can maximize the energy density of the battery by adjusting the content of the silicon material within the above content range.

[0074] Also, the negative electrode current collector is not particularly limited as long as it has high conductivity without inducing a chemical change in the battery. For example, copper, stainless steel, nickel, titanium, fired carbon, etc. can be used. In the case of copper or stainless steel, those surface-treated with carbon, nickel, titanium, silver, etc. can also be used. Also, the average thickness of the negative electrode current collector can be preferably applied in the range of 1 to 500 μm in consideration of the conductivity and total thickness of the manufactured negative electrode.

[0075] On one hand, the separator interposed between the positive electrode and the negative electrode of each unit cell is an insulating thin film having high ion permeability and mechanical strength, and is not particularly limited as long as it is commonly used in the art. Specifically, those containing one or more polymers of polypropylene, polyethylene, and polyethylene-propylene copolymer having chemical resistance and hydrophobicity can be used. The separator may have a form of a porous polymer substrate such as a sheet or nonwoven fabric containing the above-described polymer, and in some cases, may also have a form of a composite separator in which organic or inorganic particles are coated on the porous polymer substrate with an organic binder. Further, the average diameter of the pores of the separator may be 0.01 to 10 μm, and the average thickness may be 5 to 300 μm.

[0076] Furthermore, the secondary battery contains, as an electrolytic solution, the non-aqueous electrolytic solution composition according to the present invention described above.

[0077] The electrolytic solution composition contains, as an electrolytic solution additive, an ionic compound represented by the following Chemical Formula 1 having a parent nucleus in which a (meth)acrylate group or a (meth)acrylamide group is bonded via a cyclic unsaturated hydrocarbon group having a conjugated structure or a functional group having a structure in which a hetero atom is introduced into the cyclic unsaturated hydrocarbon group on one side centered on a sulfonylimide group.

[0078]

Chemical Formula

[0079] In Chemical Formula 1 above, R 1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, and R 2 is an arylene group having 6 to 20 carbon atoms, an aryleneoxy group having 6 to 20 carbon atoms, a heteroarylene group having 5 to 10 carbon atoms containing one or more hetero atoms of N, S, and O, or a heteroaryleneoxy group having 5 to 10 carbon atoms containing one or more hetero atoms of N, S, and O, and R 3is a fluoro group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or

Chemical formula

Chemical formula

[0080] By having the structure represented by the above chemical formula 1, the above compound can uniformly form an organic and / or inorganic film on the surface of the positive electrode and / or negative electrode during the activation of the secondary battery containing it. The thus uniformly formed organic and / or inorganic film can suppress the decomposition of the electrolyte and the generation of gas when the battery is exposed to high temperatures, and can improve the OCV reduction phenomenon and capacity reduction of the battery occurring at the positive electrode. Therefore, the performance and high-temperature safety of the battery can be further improved.

[0081] For this purpose, in the compound represented by the above chemical formula 1, R 1 is hydrogen, a methyl group, an ethyl group or a propyl group, R 2 is a phenylene group, a naphthalene group, an anthracenylene group, a biphenylene group, a phenyleneoxy group, a pyridinylene group, a thiophenylene group, a dioxolen group or a dithiolene group, R 3 is a fluoro group, a methyl group, an ethyl group, a propyl group, a methoxy group, an ethoxy group,

Chemical formula

[0082] Specifically, R 1 is hydrogen or a methyl group, R 2 is a phenylene group, naphthalene group, anthracenylene group, biphenylene group, phenyleneoxy group, pyridinylene group, thiophenylene group, dioxolene group or dithiolene group, and R 3 is a fluoro group, methyl group, ethyl group, propyl group, methoxy group, ethoxy group, [Chemistry] or [Chemistry] wherein X is an oxygen atom (O), -NH or -NCH 3 M is lithium, l is an integer of 1 or 2, and m can be an integer from 2 to 10.

[0083] As an example, the compound represented by the above Chemical Formula 1 can be any one or more of the following Compounds <Structural Formula 1> to <Structural Formula 48>.

[0084] [Chemistry]

[0085] [Chemistry]

[0086] [Chemical]

[0087] [Chemical]

[0088] Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples.

[0089] However, the following Examples and Experimental Examples are merely illustrative of the present invention, and the content of the present invention is not limited to the following Examples and Experimental Examples.

[0090] <Manufacture of Electrolyte Compositions for Lithium Secondary Batteries in Examples 1 to 5 and Comparative Examples 1 to 6> LiPF as a lithium salt was dissolved in a solvent obtained by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) at a volume ratio of 3:7 at a concentration of 1 M, and as shown in Table 1 below, an electrolyte additive was weighed and dissolved based on the total weight of the electrolyte to produce a non-aqueous electrolyte composition. 6

[0091] [Table 1]

[0092] <Manufacture of Electrolyte Composition for Lithium Secondary Battery in Comparative Example 7> A non-aqueous electrolyte composition for a lithium secondary battery was produced in the same manner as in Example 1, except that an oligomer (weight average molecular weight: 2,500 to 5,000) obtained by polymerizing the compound represented by the following Structural Formula 25 was used instead of the compound represented by Structural Formula 25 as the electrolyte additive.

[0093] <Manufacture of Lithium Secondary Batteries in Examples 8 to 14 and Comparative Examples 8 to 14> LiNi with a particle size of 5 μm as the positive electrode active material 0.5 Mn 1.5 O 4Prepare it, mix it with a carbon-based conductive agent and polyvinylidene fluoride as a binder in a weight ratio of 94:3:3 in N-methylpyrrolidone (NMP) to form a slurry, cast it on an aluminum thin plate, dry it in a vacuum oven at 120 °C, and then roll it to produce a positive electrode.

[0094] Separately, prepare a negative electrode active material in which artificial graphite and silicon oxide (SiO 2 ) are mixed at a weight ratio of 9:1, mix 97 parts by weight of the negative electrode active material and 3 parts by weight of styrene-butadiene rubber (SBR) with water to form a slurry, cast it on a copper thin plate, dry it in a vacuum oven at 130 °C, and then roll it to produce a negative electrode.

[0095] Interpose a separator made of 18 μm polypropylene between the obtained positive electrode and negative electrode, insert it into a case, and then inject the electrolyte compositions manufactured in Examples 1 to 7 and Comparative Examples 1 to 7 as shown in Table 2 below to manufacture a lithium secondary battery.

[0096]

Table 2

[0097] <Experimental Example 1> In order to analyze the form in which the electrolyte composition for a lithium secondary battery according to the present invention exists in a secondary battery, the following experiments were conducted on the electrolyte compositions manufactured in Example 1, Comparative Example 1, and Comparative Example 7, respectively.

[0098] i) Raman spectroscopic analysis Using a laser of 532 nm, Raman spectroscopic analysis was performed on the electrolyte composition (5 ml) manufactured in Example 1 in the wavelength range of 650 to 760 cm -1 .

[0099] As a result, the electrolyte composition of the example containing the electrolyte additive represented by Chemical Formula 1 according to the present invention, compared with the electrolyte composition manufactured in Comparative Example 1 that does not contain the electrolyte additive, is 743 ± 1 cm -1It was confirmed that the band intensity of the Raman spectrum increased in the vicinity. This is a phenomenon that appears when the negatively charged nitrogen atom and the positively charged lithium ion (Li + ) in the sulfonylimide of the electrolyte additive represented by Chemical Formula 1 form a coordination bond between ionic substances, which means that an ionic compound is contained in the electrolyte composition of Example 1. Also, the increase in the band intensity as described above indicates that the ionic compound can undergo a reduction reaction on the negative electrode surface.

[0100] (b) Differential capacitance curve analysis of half-cells A half-cell was fabricated using lithium metal and graphite (artificial graphite:natural graphite = 9:1 by weight ratio), and the electrolyte compositions produced in Example 1, Comparative Example 1, and Comparative Example 7 were respectively injected into the above half-cell. Then, it was charged to 0.05 V at a rate of 0.005 C at 3.5 ± 0.5 V at 25°C, the potential value (V) and the capacitance value (mAh) were measured, and then the capacitance value compared with the potential value was differentiated (dQ / dV) to determine the reduction potential value.

[0101] As a result, the electrolyte composition of the example containing the electrolyte additive represented by Chemical Formula 1 according to the present invention is different from the electrolyte compositions of Comparative Example 1 and Comparative Example 7 that do not contain the electrolyte additive or contain the electrolyte additive in an oligomeric form, and it was confirmed that a descending peak is shown at a voltage near 1.40 V compared to lithium. The above descending peak means that a reduction reaction occurred on the electrode surface of the graphite, which is the negative electrode, indicating that the electrolyte additive represented by Chemical Formula 1 contained in the electrolyte composition is converted into a film substance by a reduction reaction on the negative electrode surface at around 1.40 V compared to lithium.

[0102] (c) Evaluation of linear sweep voltammetry of a three-electrode cell A three - electrode battery containing a platinum electrode, a platinum electrode, and a lithium metal electrode was fabricated by injecting the electrolyte compositions prepared in Example 1, Comparative Example 1, and Comparative Example 7 into the battery respectively. Linear sweep voltammetry (LSV) analysis was performed on each of the fabricated batteries. At this time, the linear sweep voltammetry (LSV) was carried out under the conditions of an observation range of 3.0 - 6.0 V (lithium reference), a step voltage of 50 mV, and a measurement rate of 50 mV / s.

[0103] As a result, it can be seen that in the electrolyte composition of the example containing the electrolyte additive represented by Chemical Formula 1 according to the present invention, the current increases around 4.0 ± 0.05 V compared with lithium. This means that an oxidation reaction occurs on the surface of the lithium metal around 4.0 ± 0.05 V. When the electrolyte additive contained in the electrolyte composition of Example 1 reaches a condition of 4.0 ± 0.05 V or more compared with lithium, it indicates that a film is formed on the positive electrode surface by an oxidation reaction. Also, in the carbon electrode or the positive electrode, due to the catalytic properties of carbon or transition metals, it is shown that an oxidation reaction is induced at a potential lower than the electrode surface of platinum. On the other hand, in the electrolyte compositions of Comparative Example 1 and Comparative Example 7 that do not contain the electrolyte additive or contain the electrolyte additive in an oligomeric form, no increase in current was confirmed around 4.0 ± 0.05 V.

[0104] From these results, it can be seen that the electrolyte additive according to the present invention is an ionic substance, which undergoes an oxidation reaction and a reduction reaction at the positive electrode and the negative electrode respectively during the charge and discharge of the battery, thereby forming a film on the surface of each electrode.

[0105] <Experimental Example 2> In order to analyze the film formed on the electrode surface during the activation of the lithium secondary battery according to the present invention and evaluate the high - temperature safety of the lithium secondary battery, the following experiments were carried out. At this time, the target lithium secondary battery had LiNi 0.6 Co 0.2 Mn 0.2 O 2Secondary batteries of Examples 15 to 21 and Comparative Examples 15 to 21 were used, which were manufactured by performing the same method as in Examples 8 to 14 and Comparative Examples 8 to 14, except that they contained artificial graphite as the negative electrode active material.

[0106] (A) Film analysis of electrode surface For the secondary batteries of Example 15, Comparative Example 15, and Comparative Example 21, charge and discharge were performed three times each with a charge-discharge current density of 0.33C / 0.33C, a charge termination voltage of 4.2V (NMC / graphite), and a discharge termination voltage of 2.5V (NMC / graphite). X-ray photoelectron spectroscopy (XPS) was performed on the surfaces of the positive and negative electrodes of each battery in a fully discharged state.

[0107] As a result, in the secondary battery containing the electrolyte composition of Example 1 (Example 15), during X-ray photoelectron spectroscopy (XPS) of the electrode surface, both the positive and negative electrodes were shown to have peaks in the range of 280 to 300 eV indicating the binding energy of carbon and fluorine. Specifically, the positive and negative electrodes of the above secondary battery showed a peak indicating the binding energy of the CF 3 group at 293 ± 0.2 eV, which means that the electrolyte additive represented by Chemical Formula 1 contained in the electrolyte composition participated in the formation of the film formed on the surfaces of the positive and negative electrodes. On the other hand, the secondary battery using the electrolyte composition of Comparative Example 1 that does not contain the electrolyte additive (Comparative Example 15) and the secondary battery using the electrolyte composition of Comparative Example 7 that contains the oligomeric form of the electrolyte additive (Comparative Example 21) were confirmed not to show binding energy peaks derived from the CF 3 group at both the positive and negative electrodes.

[0108] From these results, it can be seen that the electrolyte additive according to the present invention can form a film on the electrode surface during the activation of the secondary battery by containing the ionic compound in the single molecular form represented by Chemical Formula 1.

[0109] (B) Evaluation of high-temperature storage stability of secondary battery For each secondary battery, while storing at 60°C for 56 days, (1) the amount of gas generated inside the secondary battery, (2) the OCV of the secondary battery was observed over time, and (3) the capacity retention rate before and after high-temperature storage was analyzed.

[0110] Specifically, for each secondary battery, charge and discharge were performed 3 times each with a charge and discharge current density of 0.33C / 0.33C, a charge termination voltage of 4.2V (NMC / graphite), and a discharge termination voltage of 2.5V (NMC / graphite) to measure the capacity of the battery. After fully charging in CC / CV mode at 0.33C and a charge termination voltage of 4.2V, high-temperature storage was started. At this time, the above high-temperature storage was stored in a constant-temperature chamber at 60°C for a total of 56 days. After 56 days had passed, the OCV deviation before and after storage (i.e., the degree of OCV decrease) and the capacity retention rate were measured, and the volume of gas generated inside the secondary battery after high-temperature storage was measured using Archimedes' principle. The results are shown in Table 3 below.

[0111]

Table 3

[0112] As shown in Table 3 above, it can be seen that for the secondary battery of the example containing the compound represented by Chemical Formula 1 according to the present invention as an electrolyte additive, even when exposed to high-temperature conditions, the decomposition of the electrolyte is reduced by the film formed on the surfaces of the positive and negative electrodes, and the amount of gas generated is significantly reduced, and the OCV decrease phenomenon occurring at the positive electrode is reduced.

[0113] Above, the present invention has been described with reference to preferred embodiments, but those skilled in the art or those having ordinary knowledge in the technical field will understand that the present invention can be variously modified and changed without departing from the spirit and technical scope of the present invention described in the claims to be described later.

[0114] Therefore, the technical scope of the present invention should not be limited to the content described in the summary of the invention in the specification, but should be determined by the claims.

Claims

1. containing a compound represented by the following Chemical Formula 1, 【Chemical Formula 1】 in the Chemical Formula 1, R １ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ２ includes an arylene group having 6 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a heteroarylene group having 5 to 10 carbon atoms containing one or more heteroatoms among N, S and O, or a heteroaryloxy group having 5 to 10 carbon atoms containing one or more heteroatoms among N, S and O, R ３ is a fluoro group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or [Chemical Formula 2] where, and one or more of the hydrogen atoms contained in the alkyl group, alkoxy group, and [Chemical Formula 3] of R3 may be substituted with a fluorine atom, X is an oxygen atom (O) or -NR ４ wherein R ４ is hydrogen or an alkyl group having 1 to 4 carbon atoms, M includes one or more selected from the group consisting of lithium, sodium, potassium, tetraalkylammonium having 1 to 4 carbon atoms, and tetraalkylphosphonium having 1 to 4 carbon atoms, l is an integer from 1 to 6, m is an integer from 2 to 20, an electrolyte additive for a secondary battery.

2. R １ is a hydrogen or methyl group, R ２ is a phenylene group, naphthalene group, anthracenylene group, biphenylene group, phenyleneoxy group, pyridinylene group, thiophenylene group, dioxolene group or dithiolene group, R ３ is a fluoro group, a methyl group, an ethyl group, a propyl group, a methoxy group, an ethoxy group, a trifluoromethyl group, 【Chemical 4】 or 【Chemical Formula 5】 where, X is an oxygen atom (O), -NH or -NCH ３ and is M is lithium, l is an integer of 1 or 2, m is an integer from 2 to 10, the electrolyte additive for a secondary battery according to Claim 1.

3. The compound represented by Chemical Formula 1 is one or more compounds selected from the following <Structural Formula 1> to <Structural Formula 48>, the electrolyte additive for a secondary battery according to Claim 1 or 2. 【Chemical Formula 6】 【Chemical Formula 7】 [Chemical Formula 8] 【Chemical Formula 9】

4. containing a non-aqueous organic solvent, a lithium salt, and a compound represented by the following Chemical Formula 1, 【Chemical Formula 10】 in the Chemical Formula 1, R １ is hydrogen or an alkyl group having 1 to 4 carbon atoms, R ２ includes an arylene group having 6 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a heteroarylene group having 5 to 10 carbon atoms containing one or more heteroatoms selected from N, S, and O, or a heteroaryloxy group having 5 to 10 carbon atoms containing one or more heteroatoms selected from N, S, and O, R ３ is a fluoro group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or 【Chemical 11】 where, and one or more of the hydrogen atoms contained in the alkyl group, alkoxy group, and [Chemical Formula 12] of R3 may be substituted with a fluorine atom, X is an oxygen atom (O) or -NR ４ wherein R ４ is hydrogen or an alkyl group having 1 to 4 carbon atoms, M includes one or more selected from the group consisting of lithium, sodium, potassium, tetraalkylammonium having 1 to 4 carbon atoms, and tetraalkylphosphonium having 1 to 4 carbon atoms, l is an integer from 1 to 6, m is an integer from 2 to 20, an electrolyte composition for a secondary battery.

5. The compound represented by Chemical Formula 1 is contained in an amount of 0.01 to 3% by weight based on the total weight of the electrolyte composition, the electrolyte composition for a secondary battery according to Claim 4.

6. The lithium salt is LiCl, LiBr, LiI, LiClO ４ , LiBF ４ , LiB １０ Cl １０ , LiPF ６ , LiCF ３ SO ３ , LiCF ３ CO ２ , LiAsF ６ , LiSbF ６ , LiAlCl ４ , CH ３ SO ３ Li, (CF ３ SO ２ ) ２ NLi and (FSO ２ ) ２ The electrolyte composition for a secondary battery according to claim 4, comprising one or more selected from the group consisting of NLi.

7. The non-aqueous organic solvent of claim 4 is N-methyl-2-pyrrolidinone, ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, triphosphate ester, trimethoxymethane, dioxolane derivative, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ether, methyl propionate and ethyl propionate, the electrolyte composition for a secondary battery according to claim 4.

8. A positive electrode containing one or more positive electrode active materials of lithium metal oxides represented by the following Chemical Formula 2 and Chemical Formula 3, a negative electrode containing a negative electrode active material, and a separator interposed between the positive electrode and the negative electrode An electrode assembly, The electrolyte composition for a secondary battery according to any one of claims 4 to 7, [Chemical Formula 2] Li ｘ [Ni ｙ Co ｚ Mn ｗ M １ ｖ O ２ [Chemical Formula 3] LiM ２ ｐ Mn （２－ｐ） O ４ In the Chemical Formula 2 and Chemical Formula 3, M １ is one or more elements selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B and Mo, x, y, z, w and v are respectively 1.0 ≦ x ≦ 1.30, 0.5 ≦ y < 1, 0 < z ≦ 0.3, 0 < w ≦ 0.3, 0 ≦ v ≦ 0.1, and y + z + w + v = 1, M ２ is Ni, Co or Fe, and p is 0.05 ≦ p ≦ 0.6, a lithium secondary battery.

9. The positive electrode active material is LiNi ０．８ Co ０．１ Mn ０．１ O ２ 、LiNi ０．６ Co ０．２ Mn ０．２ O ２ 、LiNi ０．９ Co ０．０５ Mn ０．０５ O ２ 、LiNi ０．６ Co ０．２ Mn ０．１ Al ０．１ O ２ 、LiNi ０．６ Co ０．２ Mn ０．１５ Al ０．０５ O ２ 、LiNi ０．７ Co ０．１ Mn ０．１ Al ０．１ O ２ 、LiNi ０．５ Mn １．５ O ４ The lithium secondary battery according to claim 8, comprising one or more selected from the group consisting of

10. The negative electrode active material is composed of a carbon material and a silicon material, The silicon material is one or more of silicon (Si), silicon carbide (SiC), and silicon oxide (SiO ｑ , provided that 0.8 ≦ q ≦ 2.5), The lithium secondary battery according to claim 8.

11. The silicon material is contained in an amount of 1 to 20% by weight based on the total weight of the negative electrode active material, the lithium secondary battery according to claim 10.

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