Lithium secondary battery

Abstract

The present invention relates to a lithium secondary battery comprising: an anode; a cathode opposing the anode; a separator interposed between the anode and the cathode; and a nonaqueous electrolyte, wherein the anode includes a current collector, an anode active material layer positioned on at least one surface of the current collector, and a coating layer positioned on at least a portion of a surface of the anode active material layer, and in XPS analysis of the coating layer, the atomic ratio of sulfur (S) to nitrogen (N) is 0.500 to 1.550, the atomic ratio of sulfur (S) to carbon (C) is 0.018 to 0.059, and the atomic ratio of nitrogen (N) to carbon (C) is 0.022 to 0.037.

Description

lithium secondary battery

[0001] The present invention relates to a lithium secondary battery.

[0002] As dependence on electrical energy gradually increases in modern society, the development of large-capacity power storage devices capable of stably supplying power while simultaneously increasing production is emerging. Furthermore, the need for high-capacity portable power is growing due to the performance improvements of electronic products, ranging from small devices such as mobile phones to medium-to-large devices such as electric vehicles. Lithium-ion batteries, which possess the highest potential, satisfy high-capacity power storage performance requirements and are therefore utilized in a wide range of applications, from small electronic devices to electric vehicles (EVs) and energy storage systems (ESS).

[0003] The above lithium secondary battery generally consists of a positive electrode containing a positive active material, a negative electrode containing a negative active material, an electrolyte serving as a medium for transporting lithium ions, and a separator. In this case, carbon-based active materials, silicon-based active materials, lithium transition metal oxides, lithium metal, etc., may be used as the negative electrode active material. Additionally, lithium transition metal oxides such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium nickel-cobalt-manganese composite oxide, and lithium iron phosphate may be used as the positive electrode active material.

[0004] During the charging of a lithium secondary battery, lithium ions are generated from the positive electrode and can be converted into stacked or alloyed forms for storage on the negative electrode, while discharge proceeds in the opposite direction. Theoretically, the movement of lithium ions to the positive and negative electrodes during charging and discharging of such lithium secondary batteries should be reversible; however, in reality, the movement of lithium within the battery may be partially irreversible. Specifically, the medium through which lithium ions can move is the electrolyte. During charging, most lithium ions are stacked or alloyed within the negative electrode active material; however, some are reduced together with the organic and inorganic materials constituting the electrolyte to form nano-sized organic-inorganic composites on the surface of the negative electrode material. This represents an irreversible, permanent loss of lithium ions provided by the positive electrode, and the organic-inorganic film formed in this way is called the solid electrolyte interface layer (SEI layer). Meanwhile, on the surface of the positive electrode active material, a solid electrolyte interface layer can be formed through the oxidation reaction of the materials constituting the electrolyte. When the above solid electrolyte interface layer is formed, irreversible loss of lithium ions is reduced, and a wide driving potential of the electrolyte is secured, enabling smooth reversible movement of lithium ions between the anode and the cathode. Since this solid electrolyte interface layer can contribute to lowering the energy barrier required for charge transfer of lithium ions to the cathode or anode depending on its internal components, the proper design of the solid-electrolyte interface layer has been a research task for improving the performance of lithium secondary batteries.

[0005] Specifically, the lifespan characteristics and durability of lithium secondary batteries can be determined by the stability of the solid-electrolyte interface layer. For example, as charging and discharging progresses, the instability of the initially formed solid-electrolyte interface layer can lead to additional reduction of lithium ions on the surface of the anode material, resulting in the formation of a film thicker than the initially formed interface layer. Due to the loss of additional lithium ions, an additional interface layer thicker than the initially formed one may develop on the surface of the cathode material, or structural degradation of the cathode material may occur. This can be one of the causes of increased resistance in lithium secondary batteries. When lithium secondary batteries are exposed to high temperatures, the materials constituting the electrolyte undergo decomposition; the resulting by-products can degrade the performance of the electrolyte and increase the resistance of the lithium secondary battery. As lithium secondary batteries are exposed to high temperatures and undergo repeated charging and discharging cycles, the increase in resistance can cause the anode and cathode to operate at voltages higher or lower than their initial lifespan. Consequently, the oxidation and reduction reactions of the electrolyte at the anode and cathode are accelerated, which can degrade the performance of the lithium secondary battery. Additionally, instability in the solid-electrolyte interface layer can lead to continuous oxidation and reduction reactions of the electrolyte, resulting in gas generation within the lithium secondary battery. In other words, strengthening the stability of the solid-electrolyte interface layer is a critical task for ensuring stable operation and securing battery performance characteristics such as long lifespan, high-temperature durability, and reduced gas generation.

[0006] The present invention aims to solve the above-mentioned problems by increasing the stability of the solid-electrolyte interface layer formed on the cathode and including a component having low resistance in the solid-electrolyte interface layer, thereby improving low-temperature life, low-temperature output, fast charging, room-temperature life, high-temperature storage characteristics, and high-temperature life characteristics, and providing a lithium secondary battery with improved overall performance.

[0007] [1] The present invention provides a lithium secondary battery comprising: a cathode; an anode facing the cathode; a separator interposed between the cathode and the anode; and a non-aqueous electrolyte; wherein the cathode comprises a current collector, a cathode active material layer located on at least one surface of the current collector, and a coating layer located on at least a portion of the surface of the cathode active material layer; wherein, when XPS analysis is performed on the coating layer, the atomic ratio of sulfur (S) to nitrogen (N) is 0.500 to 1.550, the atomic ratio of sulfur (S) to carbon (C) is 0.018 to 0.059, and the atomic ratio of nitrogen (N) to carbon (C) is 0.022 to 0.037.

[0008] [2] The present invention provides a lithium secondary battery according to [1], wherein the negative electrode active material layer comprises a negative electrode active material, and the negative electrode active material comprises at least one selected from carbon-based active material and silicon-based active material.

[0009] [3] The present invention provides a lithium secondary battery in which, in at least one of [1] and [2], the positive electrode comprises a current collector and a positive electrode active material layer located on at least one surface of the current collector, the positive electrode active material layer comprises a lithium metal composite oxide, and the lithium metal composite oxide comprises at least one selected from lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese oxide, lithium over-manganese-rich oxide and lithium iron phosphate.

[0010] [4] The present invention provides a lithium secondary battery in which, in at least one of [1] to [3], the coating layer comprises a compound represented by the following chemical formula 1.

[0011] [Chemical Formula 1]

[0012]

[0013] In the above chemical formula 1, L1 is an alkylene group having 1 to 10 carbon atoms, M is a metal cation or an organic cation, a is the valence of M when M is a metal cation, 1 when M is an organic cation, and a × n = 2 × m.

[0014] [5] The present invention provides a lithium secondary battery in which the compound represented by the chemical formula 1 in [4] is the compound represented by the chemical formula 1-A below.

[0015] [6] The present invention provides a lithium secondary battery in which, in at least one of [4] and [5], M is a metal cation and M is selected from the group consisting of Li, K, Ca, Mg and Cs.

[0016] [7] The present invention provides a lithium secondary battery in which, in at least one of [4] to [6], M is an organic cation and M is selected from the group consisting of compounds represented by the following chemical formulas M-1 to M-6.

[0017] [Chemical Formula M-1]

[0018]

[0019] In the above chemical formula M-1, X M1 is -N(R M15 )- or -S- and, R M11 , R M12 , R M13 , R M14 and R M15 The groups are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.

[0020] [Chemical Formula M-2]

[0021]

[0022] In the above chemical formula M-2, X M2 is -N(R M25 )- or -S- and, R M21 , R M22 , R M23 , R M24 and R M25 The groups are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.

[0023] [Chemical Formula M-3]

[0024]

[0025] In the above chemical formula M-3, R M31 , R M32 , R M33 , R M34 , R M35 and R M36 The groups are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.

[0026] [Chemical Formula M-4]

[0027]

[0028] In the above chemical formula M-4, R M41 , R M42 , R M43 and R M44 is independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and RM41 , R M42 , R M43 and R M44 At least two of them are alkyl groups having 1 to 5 carbon atoms, and they can be bonded together to form an aliphatic hydrocarbon ring.

[0029] [Chemical Formula M-5]

[0030]

[0031] In the above chemical formula M-5, R M51 , R M52 , R M53 and R M54 is independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and R M51 , R M52 , R M53 and R M54 At least two of these can be combined to form an aliphatic hydrocarbon ring.

[0032] [Chemical Formula M-6]

[0033]

[0034] In the above chemical formula M-6, R M61 , R M62 and R M63 is independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoethyl group having 1 to 12 carbon atoms, an alkoxyalkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and R M61 , R M62 and R M63 At least two of these can be combined to form an aliphatic hydrocarbon ring.

[0035] [8] The present invention provides a lithium secondary battery in which, in at least one of [4] to [7], the compound represented by Formula 1 is a compound represented by Formula 1-1 below.

[0036] [Chemical Formula 1-1]

[0037]

[0038] [9] The present invention provides a lithium secondary battery in which, in at least one of [1] to [8], peaks are found at 401 eV to 395 eV and 172 eV to 168 eV in the intensity-binding energy graph according to XPS analysis of the coating layer.

[0039]

[0010] The present invention provides a lithium secondary battery in which, in at least one of [1] to [9], the atomic ratio of sulfur (S) to nitrogen (N) in the coating layer is 0.794 to 1.520 when XPS analyzed.

[0040]

[0011] The present invention provides a lithium secondary battery in which, in at least one of [1] to

[0010] , the elemental ratio of sulfur (S) to carbon (C) in the coating layer during XPS analysis is 0.018 to 0.055.

[0041]

[0012] The present invention provides a lithium secondary battery in which, in at least one of [1] to

[0011] , the elemental ratio of nitrogen (N) to carbon (C) in the coating layer during XPS analysis is 0.023 to 0.037.

[0042] A lithium secondary battery according to the present invention comprises a coating layer disposed at least partially on the surface of a negative electrode active material layer, and is characterized in that, upon XPS analysis of the coating layer, the elemental ratio of nitrogen (N), sulfur (S), and / or carbon (C) satisfies a specific range. A lithium secondary battery equipped with a negative electrode comprising the above-described coating layer can act as a robust solid-electrolyte interface layer that does not easily decompose during the operation of the lithium secondary battery. The coating layer is desirable in that it can enhance the durability of the negative electrode and reduce resistance, and can significantly prevent gas generation caused by the decomposition of the solid-electrolyte interface layer components. Therefore, such a lithium secondary battery can exhibit excellent lifespan and storage performance even under conditions such as high temperature and high voltage, while simultaneously improving output performance at low temperatures.

[0043] FIG. 1 is a schematic side view illustrating the electrode of the present invention.

[0044] Figure 2 shows the XIC results for the compound represented by chemical formula 2-a-1.

[0045] Figure 3 is the MS spectrum for the compound represented by the chemical formula 2-a-1.

[0046] Figure 4 shows the results of MS / MS analysis (Tandem MS, dual mass spectrometry) for a compound represented by chemical formula 2-a-1.

[0047] Figure 5 is the ¹H-NMR spectrum for a preparation solution of the compound represented by chemical formula 2-a-1.

[0048] Figure 6 is the ¹H-NMR spectrum of the coating layer according to Example 1.

[0049] Figure 7 is the ¹H-NMR spectrum of the coating layer according to Example 2.

[0050] Figure 8 is the ¹H-NMR spectrum of the coating layer according to Example 3.

[0051] Figure 9 is a graph evaluating the cycle capacity retention rate of lithium secondary batteries of the examples and comparative examples.

[0052] The terms and words used in this specification and claims are used merely to describe exemplary embodiments and should not be interpreted as being limited to their ordinary or dictionary meanings, and should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0053] For example, in this specification, terms such as “comprising,” “having,” or “having” are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0054] In addition, in the description of "a to b carbon atoms" within this specification, "a" and "b" refer to the number of carbon atoms included in a specific functional group. That is, the functional group may include "a" to "b" carbon atoms. For example, "alkylene group having 1 to 5 carbon atoms" refers to an alkylene group containing 1 to 5 carbon atoms, namely -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH2(CH2)CH-, -CH2CH2CH2CH2CH2-, and -CH(CH2)CH2CH2-, etc.

[0055] Additionally, in this specification, the term "alkylene group" refers to a branched or unbranched aliphatic hydrocarbon group or a functional group in which one hydrogen atom is removed from each carbon atom located at both ends of the aliphatic hydrocarbon group. In one embodiment, the alkylene group may be substituted or unsubstituted. The alkylene group includes, but is not limited to, methylene groups, ethylene groups, propylene groups, isopropylene groups, butylene groups, isobutylene groups, tert-butylene groups, pentylene groups, 3-pentylene groups, etc., and each of these may be optionally substituted in other embodiments.

[0056] Additionally, in this specification, "substitution" means that at least one hydrogen bonded to carbon is substituted with another element, such as fluorine, unless otherwise defined.

[0057] Additionally, in this specification, "*" refers to a bonding site in a chemical formula unless otherwise defined.

[0058]

[0059] The present invention will be described in more detail below.

[0060]

[0061] lithium secondary battery

[0062] The present invention relates to a lithium secondary battery.

[0063] Specifically, the lithium secondary battery according to the present invention comprises: a negative electrode; a positive electrode facing the negative electrode; a separator interposed between the negative electrode and the positive electrode; and a non-aqueous electrolyte.

[0064] The above lithium secondary battery can be manufactured by housing an electrode assembly comprising the positive electrode; a negative electrode facing the positive electrode; and a separator interposed between the positive electrode and the negative electrode in a battery case, and then injecting a non-aqueous electrolyte.

[0065]

[0066] (1) Cathode

[0067] The cathode of the present invention will be described in detail below with reference to the drawings. In assigning reference numerals to the components of each drawing, the same components may have the same reference numeral as much as possible, even if they are shown in different drawings. Furthermore, in describing the present invention, if it is determined that a detailed description of related known components or functions could obscure the essence of the present invention, such detailed description may be omitted.

[0068] Specifically, referring to FIG. 1, the cathode (10) according to the present invention may include a current collector (100); a cathode active material layer (110) located on at least one surface of the current collector (100); and a coating layer (120) located on at least a portion of the surface of the cathode active material layer (110).

[0069]

[0070] Whole house (100)

[0071] The above current collector (100) can be named a negative current collector.

[0072] The current collector (100) is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Specifically, the current collector (100) may be copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface treated with carbon, nickel, titanium, silver, etc., or an aluminum-cadmium alloy. Specifically, the current collector (100) may include copper.

[0073] The current collector (100) may form fine irregularities on its surface to strengthen the bonding force of the active material. For example, the current collector (100) can be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0074] The current collector (100) can typically have a thickness of 3 µm to 500 µm, specifically 5 µm to 20 µm.

[0075]

[0076] cathode active material layer (110)

[0077] The above negative active material layer (110) may be disposed on at least one surface of the current collector (100). Specifically, as shown in FIG. 1, the negative active material layer (110) may be disposed on one surface of the current collector (100). Alternatively, the negative active material layer (110) may be disposed on both surfaces of the current collector (100).

[0078] The above negative electrode active material layer (110) may include a negative electrode active material.

[0079] The above-mentioned negative electrode active material is a material capable of reversibly inserting / extracting lithium ions and may include at least one selected from the group consisting of carbon-based active materials, (quasi)metal-based active materials, and lithium metal, and specifically may include at least one selected from carbon-based active materials and (quasi)metal-based active materials. More specifically, the above-mentioned negative electrode active material may include at least one selected from carbon-based active materials and silicon-based active materials. Alternatively, the above-mentioned negative electrode active material may include carbon-based active materials. Meanwhile, the above-mentioned negative electrode active material may be a negative electrode active material of a lithium-sulfur battery, and the negative electrode active material may be a carbon-based active material or lithium metal.

[0080] The carbon-based active material may include at least one selected from the group consisting of graphite, hard carbon, soft carbon, carbon black, graphene, and fibrous carbon, and preferably may include graphite. The graphite may be, for example, at least one of artificial graphite and natural graphite.

[0081] Average particle size (D of the above carbon-based active material) 50 ) can be 10㎛ to 30㎛, preferably 15㎛ to 25㎛, in terms of ensuring structural stability during charging and discharging and reducing adverse reactions with the electrolyte.

[0082] Specifically, the (quasi)metallic active material comprises: at least one (quasi)metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Fe, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; an alloy of lithium and at least one (quasi)metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Fe, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; an oxide of at least one (quasi)metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Fe, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; lithium titanium oxide (LTO); and lithium vanadium oxide. It may include the back.

[0083] More specifically, the above (quasi)metallic active material may include a silicon-based active material.

[0084] The above silicon-based active material is SiO x It may include at least one selected from the group consisting of compounds represented by (0≤x<2) and silicon-carbon composites. Since SiO2 does not react with lithium ions and therefore cannot store lithium, it is preferable that x be within the above range, and more preferably, the silicon-based active material may be SiO.

[0085] Average particle size (D) of the above silicon-based active material 50 ) can be 1㎛ to 30㎛, preferably 2㎛ to 15㎛, in terms of reducing adverse reactions with the electrolyte while ensuring structural stability during charging and discharging.

[0086] In addition, the above negative electrode active material may include at least one selected from the above carbon-based active material and silicon-based active material.

[0087] For example, the cathode of the present invention may include the carbon-based active material and the silicon-based active material. In this case, the weight ratio of the silicon-based active material to the carbon-based active material may be 1:99 to 30:70, specifically 3:97 to 15:85. When the mixing ratio of the silicon-based active material and the carbon-based active material satisfies the above range, excellent cycle performance can be secured by suppressing the volume expansion of the silicon-based active material while improving capacity characteristics.

[0088] The above negative electrode active material may be included in the negative electrode active material layer in an amount of 60% to 99% by weight in order to sufficiently express capacity in the secondary battery.

[0089] The above cathode active material layer may further include a conductive material and / or a binder together with the cathode active material.

[0090] The above binder can be used to improve the adhesion between the cathode active material layer and the current collector, or to improve the bonding strength between the cathode active materials.

[0091] Specifically, in terms of further improving electrode adhesion and providing sufficient resistance to volume expansion / contraction of the negative electrode active material, the binder comprises styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR), acrylonitrile butadiene rubber, acrylic rubber, butyl rubber, fluoro rubber, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyethylene glycol (PEG), polyacrylonitrile (PAN), polyacryl amide (PAM), polyvinylidene fluoride, polytetrafluoroethylene, It may include at least one selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene.

[0092] The binder may be included in the cathode active material layer in an amount of 1% to 30% by weight, specifically 1% to 5% by weight, and when within this range, the cathode active material can be better bound to minimize the volume expansion problem of the active material, while at the same time facilitating the dispersion of the binder during the preparation of a slurry for forming the cathode active material layer and improving the coating properties and phase stability of the slurry.

[0093] The above conductive material may be used to assist and improve conductivity in a secondary battery, and is not particularly limited as long as it is conductive without causing chemical changes. Specifically, the above conductive material may include at least one selected from the group consisting of graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, ketjen black, channel black, Farnes black, lamp black, thermal black; conductive fibers such as carbon fibers or metal fibers; conductive tubes such as carbon nanotubes; metal powders such as fluorocarbon, aluminum, or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and polyphenylene derivatives.

[0094] The conductive material may be included in the cathode active material layer in an amount of 1% to 20% by weight, specifically 1% to 5% by weight, and is desirable in that it can form an excellent conductive network while mitigating the increase in resistance caused by the binder when in this range.

[0095] The thickness of the above negative electrode active material layer may be 5㎛ to 500㎛, preferably 5㎛ to 200㎛.

[0096] The above cathode may be manufactured by coating a cathode slurry comprising a cathode active material and optionally a binder, a conductive material, and a solvent for forming a cathode slurry onto the cathode current collector, and then drying and rolling. Alternatively, the cathode may be manufactured by mixing a cathode active material and optionally a binder, a conductive material, etc. to produce a film, and then laminating it onto a cathode current collector.

[0097] The solvent for forming the above cathode slurry may include, for example, at least one selected from the group consisting of distilled water, N-methylpyrrolidone, ethanol, methanol, and isopropyl alcohol, preferably distilled water, in order to facilitate the dispersion of the cathode active material, binder, and / or conductive material.

[0098]

[0099] coating layer (120)

[0100] The coating layer (120) may be located on at least a portion of the surface of the cathode active material layer (110). Specifically, the coating layer (120) may be placed over 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more of the surface area of ​​the cathode active material layer (110). The coating layer (120) may be placed over 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more of the surface area of ​​the cathode active material layer (110). The coating layer (120) may be placed over 100% or less or less than 100% of the surface area of ​​the cathode active material layer (110). The coating layer (120) can be placed over the entire surface of the cathode active material layer (110).

[0101] The coating layer (120) may be disposed on the surface of the negative active material layer (110). For example, the coating layer (120) may be disposed on the opposite side of the surface of the negative active material layer (110) that contacts the current collector (100). Meanwhile, if the negative active material layer is disposed on both sides of the current collector, the coating layer (120) may be disposed on the surfaces of each of the two negative active material layers.

[0102] The coating layer (120) may include nitrogen (N) element, sulfur (S) element and carbon (C) element.

[0103] When XPS analysis of the coating layer (120), the atomic ratio of sulfur (S) to nitrogen (N) may be 0.500 to 1.550, the atomic ratio of sulfur (S) to carbon (C) may be 0.018 to 0.059, and the atomic ratio of nitrogen (N) to carbon (C) may be 0.022 to 0.037.

[0104] The coating layer (120) may be, for example, a solid electrolyte interface layer (SEI layer) formed on the surface of the negative electrode active material layer (110).

[0105] Through XPS analysis of the coating layer (120), it is possible to determine the presence of nitrogen (N), sulfur (S), and carbon (C) present in the coating layer and the ratio of their content. When the above range is satisfied, the durability of the coating layer is improved, and problems such as organic solvent consumption and gas generation due to side reactions between the negative electrode active material layer and the electrolyte can be prevented. Furthermore, when the above range is satisfied, lithium ion diffusion can be improved, thereby reducing resistance. High-temperature durability is excellent, minimizing reversible lithium ion loss and effectively suppressing the decomposition of the solid-electrolyte interface layer by transition metals generated from the anode. This has an advantage in that it enables improved output performance even under low-temperature conditions where lithium ion mobility characteristics are problematic.

[0106] Accordingly, in the case of a cathode comprising a coating layer satisfying the above characteristics and a lithium secondary battery comprising the same, inorganic components such as nitrogen (N) and sulfur (S) and organic components such as carbon (C) are harmoniously contained, so that the cathode can be effectively protected in an environment where adverse reactions of the electrolyte, cathode decay, or destruction of the SEI film of the cathode are likely to occur, such as at high temperature and high voltage. Accordingly, the lifespan performance and storage performance of the lithium secondary battery, particularly the lifespan performance and storage performance of the lithium secondary battery under high temperature and high voltage, can be significantly improved. In other words, the present invention is highly desirable in that it can achieve the effect of improving the output performance, lifespan performance, and storage performance of the lithium secondary battery.

[0107] In order to implement the above-described features of the lithium secondary battery of the present invention, the specified elemental ratio of sulfur (S) to nitrogen (N), the elemental ratio of sulfur (S) to carbon (C), and the elemental ratio of nitrogen (N) to carbon (C) must be satisfied simultaneously. If any of the three elemental ratios are not satisfied, the inorganic components may not be sufficiently distributed in the negative electrode active material layer, making it difficult to effectively protect the negative electrode, or problems such as side reactions, capacity reduction, and increased resistance may occur due to the introduction of excessive elements. In other words, if the three elemental ratios are not satisfied simultaneously, it is undesirable as it causes a decrease in the output performance, lifespan performance, and storage performance of the lithium secondary battery.

[0108] The coating layer (120) may, for example, be a solid-electrolyte interface layer formed on the surface of the negative electrode active material layer (110). For example, the coating layer (120) may be formed after the activation process of the lithium secondary battery is performed.

[0109] When analyzing the coating layer (120) via XPS, the atomic ratio of sulfur (S) to nitrogen (N) may be 0.500 to 1.550. Specifically, when analyzing the coating layer (120) via XPS, the atomic ratio of sulfur (S) to nitrogen (N) may be 0.500 or higher, 0.550 or higher, 0.600 or higher, 0.650 or higher, 0.700 or higher, 0.750 or higher, 0.794 or higher, 0.800 or higher, 0.850 or higher, 0.900 or higher, 0.950 or higher, 1.000 or higher, 1.050 or higher, 1.100 or higher, 1.110 or higher, 1.120 or higher, or 1.130 or higher. Specifically, when XPS analyzing the coating layer (120), the atomic ratio of sulfur (S) to nitrogen (N) may be 1.550 or less, 1.520 or less, 1.500 or less, 1.450 or less, 1.400 or less, or 1.350 or less. The above ranges may be combined without limitation.

[0110] When analyzing the coating layer (120) via XPS, the elemental ratio of sulfur (S) to carbon (C) may be 0.018 to 0.059. Specifically, when analyzing the coating layer (120) via XPS, the elemental ratio of sulfur (S) to carbon (C) may be 0.018 or higher, 0.020 or higher, 0.025 or higher, or 0.028 or higher. Specifically, when XPS analysis of the coating layer (120), the elemental ratio of sulfur (S) to carbon (C) may be 0.059 or less, 0.058 or less, 0.057 or less, 0.056 or less, 0.055 or less, 0.054 or less, 0.053 or less, 0.050 or less, 0.047 or less, 0.045 or less, 0.042 or less, 0.040 or less, 0.038 or less, 0.035 or less, or 0.032 or less. The above ranges may be combined without limitation.

[0111] When analyzing the coating layer (120) via XPS, the elemental ratio of nitrogen (N) to carbon (C) may be 0.022 to 0.037. Specifically, when analyzing the coating layer (120) via XPS, the elemental ratio of nitrogen (N) to carbon (C) may be 0.022 or higher, 0.023 or higher, 0.024 or higher, 0.025 or higher, 0.026 or higher, or 0.027 or higher. Specifically, when analyzing the coating layer (120) via XPS, the elemental ratio of nitrogen (N) to carbon (C) may be 0.037 or lower, 0.036 or lower, 0.035 or lower, 0.032 or lower, 0.031 or lower, 0.030 or lower, or 0.029 or lower. The above ranges may be combined without limitation.

[0112] The coating layer (120) may contain nitrogen (N) element in an amount of 0.80% to 2.00%, specifically 1.00% to 1.60%, more specifically 1.20% to 1.30% with respect to the total elements of the coating layer (120).

[0113] The coating layer (120) may contain sulfur (S) element in an amount of 0.80% to 3.00%, specifically 1.20% to 2.50%, more specifically 1.30% to 1.37% with respect to the total elements of the coating layer (120).

[0114] The coating layer (120) may contain carbon (C) elements in an amount of 40.00% to 50.00%, specifically 42.00% to 46.00%, more specifically 43.50% to 44.50%, relative to the total elements of the coating layer (120).

[0115] The coating layer (120) may include additional elements along with nitrogen (N) element, sulfur (S) element, and carbon (C) element. The additional elements may include at least one selected from the group consisting of lithium (Li), oxygen (O), fluorine (F) element, phosphorus (P) element, and sodium (Na) element. The additional elements may include trace amounts of other elements in addition to the elements described above. The effect of the present invention is realized through the presence of the nitrogen (N) element, sulfur (S) element, and carbon (C) element and their elemental ratios, and the additional elements may be present in the coating layer as optional components. The additional elements may be included in the coating layer as a remainder excluding the total weight of the nitrogen (N) element, sulfur (S) element, and carbon (C) element.

[0116] In the present invention, the X-ray photoelectron spectroscopy (XPS) analysis of the coating layer may be performed by, for example, by decomposing the negative electrode in a glove box with an Ar atmosphere in a lithium secondary battery with an SOC of 0%, washing and drying the decomposed negative electrode with a washing solvent (e.g., DMC solvent), fixing it in an XPS sample holder, and then measuring it with an XPS device. Additionally, to distinguish the coating layer from the negative electrode active material layer, the XPS analysis may be performed by (1) analyzing the surface as is, (2) etching with an argon single-atom sputtering gun for about 10 to 100 seconds, or (3) attaching and then removing a tape (manufactured by 3M) to the surface of the coating layer (120) to remove surface contaminants, and then analyzing the surface of the coating layer.

[0117] The measurement conditions for the above XPS analysis may be as follows.

[0118] - XPS equipment name: K-Alpha, Thermo Fisher Scientific

[0119] - X-ray source: Monochromated Al Kα (1486.6 eV)

[0120] - X-ray spot size: 400 µm

[0121] - Etching conditions (sputtering gun): monatomic Ar (energy: 1000 eV, current: low, raster width: 2 mm), 0.09 nm / s etching rate (based on Ta2O5)

[0122] - Charge compensation (flood gun): Off

[0123] - Survey scan: pass energy 200 eV, energy step 1 eV

[0124] - Narrow scan: pass energy 50 eV, energy step 0.1 eV

[0125] - Sensitivity factor (SF): Al THERMO1, Energy correction factor (ECF): TPP-2M

[0126] - Background subtraction: Smart

[0127] - Binding energy correction: Shifts the binding energy so that the CC, CH (sp3-C) peaks in the C 1s spectrum are located at 285 eV.

[0128] The thickness of the coating layer (120) may be 50 nm to 360 nm, specifically 90 nm to 315 nm, and more specifically 100 nm to 200 nm.

[0129] The thickness of the coating layer (120) may be defined as the etching thickness until the ratio of the major element of the negative electrode active material (e.g., carbon when graphite is used as the negative electrode active material) of the negative electrode active material layer (110) becomes 70 elemental% or more (specifically 70 elemental%) during XPS analysis, by using an XPS device and an argon single-atom sputtering gun to etch the coating layer. In the present invention, the XPS (X-ray photoelectron spectroscopy) analysis for measuring the thickness of the coating layer may be performed by, for example, by disassembling the negative electrode in a glove box with an Ar atmosphere in a lithium secondary battery in a state of 0% SOC, washing and drying the disassembled negative electrode with a washing solvent (e.g., DMC solvent), fixing it in an XPS sample holder, and then measuring it with an XPS device. The XPS analysis conditions may be as described above. At this time, since the coating layer has a composite structure containing multiple elements, it may be difficult to determine the exact etching rate using an argon single-atom sputtering gun. Taking this into consideration, the known etching rate (0.09 nm / sec) of tantalum pentoxide (Ta2O5) and the etching time to the etching thickness can be multiplied and assumed as the thickness of the coating layer (120).

[0130]

[0131] The method of implementing the elemental ratio of sulfur (S) to nitrogen (N), the elemental ratio of sulfur (S) to carbon (C), and / or the elemental ratio of nitrogen (N) to carbon (C) in the coating layer according to the present invention is not particularly limited. For example, it can be implemented through a solid-electrolyte interface layer formed through an activation process after controlling the type and content of an additive included in the non-aqueous electrolyte. The additive included at this time may include nitrogen (N), sulfur (S), and carbon (C). For example, the additive may be a material capable of forming a compound represented by Chemical Formula 1, described below, in the coating layer through an activation process, etc.

[0132] Specifically, the coating layer (120) may be formed by an activation process of the lithium secondary battery. The activation process may be any activation process known in the art without limitation and is not particularly limited.

[0133]

[0134] The coating layer (120) may include a compound represented by the following chemical formula 1.

[0135] [Chemical Formula 1]

[0136]

[0137] In the above chemical formula 1, L1 is an alkylene group having 1 to 10 carbon atoms, M is a metal cation or an organic cation, a is the valence of M when M is a metal cation, 1 when M is an organic cation, and a × n = 2 × m.

[0138] The compound represented by Chemical Formula 1 above does not easily decompose during the operation of a lithium secondary battery and can act as a robust solid-electrolyte interface layer. The coating layer is desirable in that it can strengthen the durability of the electrode (positive or negative electrode) and reduce resistance, and the generation of gas due to the decomposition of the solid-electrolyte interface layer components can be significantly prevented. Therefore, when the non-aqueous electrolyte of the present invention is applied to a lithium secondary battery, excellent lifespan performance and storage performance can be achieved even under conditions such as high temperature and high voltage, while output performance at low temperature can be improved.

[0139] In addition, since the compound represented by the above chemical formula 1 forms a coordinate bond with the above M (cation), the sulfate (SO4) in the structure 2-It is a material that can be stably maintained, and accordingly, does not easily undergo decomposition due to structural instability. Therefore, the electrode according to the present invention has excellent durability of the coating layer or the solid-electrolyte interface layer. In addition, the compound represented by Chemical Formula 1 can be included in the coating layer to improve the resistance characteristics of the electrode. Furthermore, for the reasons mentioned above, the compound represented by Chemical Formula 1 is desirable in terms of gas reduction because hydrocarbon gas (e.g., derived from L1) is not generated due to structural decomposition. A coating layer containing the compound represented by Chemical Formula 1 is desirable in that it can strengthen the durability of the cathode and reduce resistance, and gas generation due to the decomposition of the solid-electrolyte interface layer components can be significantly prevented.

[0140] Sulfur (S), carbon (C), etc. included in the coating layer (120) may be derived from at least some of the compounds represented by the chemical formula 1.

[0141] In the above chemical formula 1, L1 may be an alkylene group having 1 to 10 carbon atoms, specifically an alkylene group having 1 to 5 carbon atoms, more specifically an alkylene group having 1 to 3 carbon atoms, more specifically a methylene group, an ethylene group, or a propylene group, and even more specifically an ethylene group.

[0142] In the above chemical formula 1, M can be a metal cation or an organic cation.

[0143] Specifically, when M is a metal cation, M may be any one selected from the group consisting of Li, K, Ca, Mg, and Cs, and, for example, may be Li.

[0144] In addition, if M is an organic cation (i.e., a cation in the form of an organic compound), M may be any one selected from the group consisting of compounds represented by the following chemical formulas M-1 to M-6.

[0145] [Chemical Formula M-1]

[0146]

[0147] In the above chemical formula M-1, X M1 is -N(R M15 )- or -S- and, R M11 , R M12 , R M13 , R M14 and R M15 may independently be hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. Specifically, R M11 , R M12 , R M13 , R M14 and R M15 s⁻¹ may independently be hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 5 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. More specifically, in the above formula M-1, R⁻¹ M11 , R M12 , R M13 , R M14 and R M15 The groups may independently be hydrogen, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, allyl group (*-CH2CH=CH2), phenyl group, cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, 4-cyanobutyl group, methoxymethyl group, 2-methoxyethyl group, 3-methoxypropyl group, methoxy group, or ethoxy group.

[0148] [Chemical Formula M-2]

[0149]

[0150] In the above chemical formula M-2, X M2 is -N(R M25 )- or -S- is. R M21 , R M22 , R M23 , R M24 and R M25 may independently be hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 2 to 12 carbon atoms. Specifically, R M21 , R M22 , R M23 , R M24 and R M25 may independently be hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 5 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. More specifically, in the above formula M-2, R M21 , R M22 , R M23 , R M24 and R M25 The groups may independently be hydrogen, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, allyl group (*-CH2CH=CH2), phenyl group, cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, 4-cyanobutyl group, methoxymethyl group, 2-methoxyethyl group, 3-methoxypropyl group, ethoxymethyl group, 2-ethoxyethyl group, 3-ethoxypropyl group, methoxy group, or ethoxy group.

[0151] [Chemical Formula M-3]

[0152]

[0153] In the above chemical formula M-3, R M31 , R M32 , RM33 , R M34 , R M35 and R M36 may independently be hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. Specifically, R M31 , R M32 , R M33 , R M34 , R M35 and R M36 may independently be hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 5 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. More specifically, R M31 , R M32 , R M33 , R M34 , R M35 and R M36 The groups may independently be hydrogen, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, allyl group (*-CH2CH=CH2), phenyl group, cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, 4-cyanobutyl group, methoxymethyl group, 2-methoxyethyl group, 3-methoxypropyl group, ethoxymethyl group, 2-ethoxyethyl group, 3-ethoxypropyl group, methoxy group, or ethoxy group.

[0154] [Chemical Formula M-4]

[0155]

[0156] In the above chemical formula M-4, R M41 , R M42 , R M43 and R M44may independently be hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. Specifically, R M41 , R M42 , R M43 and R M44 may independently be hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 5 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. More specifically, R M41 , R M42 , R M43 and R M44 may independently be hydrogen, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, allyl group (*-CH2CH=CH2), phenyl group, cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, 4-cyanobutyl group, methoxymethyl group, 2-methoxyethyl group, 3-methoxypropyl group, ethoxymethyl group, 2-ethoxyethyl group, 3-ethoxypropyl group, methoxy group, or ethoxy group. Additionally, R M41 , R M42 , R M43 and R M44 At least two of these types may combine to form an aliphatic ring, specifically R M41 , R M42 , R M43 and R M44 At least two of them are alkyl groups having 1 to 5 carbon atoms or alkyl groups having 2 to 3 carbon atoms, and they can be bonded together to form an aliphatic hydrocarbon ring.

[0157] [Chemical Formula M-5]

[0158]

[0159] In the above chemical formula M-5, R M51 , R M52 , R M53 and R M54 may independently be hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. Specifically, R M51 , R M52 , R M53 and R M54 may independently be hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 5 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. More specifically, R M51 , R M52 , R M53 and R M54 may independently be hydrogen, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, allyl group (*-CH2CH=CH2), phenyl group, cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, 4-cyanobutyl group, methoxymethyl group, 2-methoxyethyl group, 3-methoxypropyl group, ethoxymethyl group, 2-ethoxyethyl group, 3-ethoxypropyl group, methoxy group, or ethoxy group. Additionally, R M51 , R M52 , R M53 and R M54 At least two of these types may combine to form an aliphatic ring, specifically R M51 , R M52 , R M53 and R M54At least two of them are alkyl groups having 1 to 5 carbon atoms or alkyl groups having 2 to 3 carbon atoms, and they can be bonded together to form an aliphatic hydrocarbon ring.

[0160] [Chemical Formula M-6]

[0161]

[0162] In the above chemical formula M-6, R M61 , R M62 and R M63 may independently be hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. Specifically, R M61 , R M62 and R M63 is independently hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 5 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. More specifically, R M61 , R M62 and R M63 may independently be hydrogen, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, allyl group (*-CH2CH=CH2), phenyl group, cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, 4-cyanobutyl group, methoxymethyl group, 2-methoxyethyl group, 3-methoxypropyl group, ethoxymethyl group, 2-ethoxyethyl group, 3-ethoxypropyl group, methoxy group, or ethoxy group. Additionally, R M61 , R M62 and R M63 At least two of these types may combine to form an aliphatic ring, specifically R M61 , R M62and R M63 At least two of them are alkyl groups having 1 to 5 carbon atoms or alkyl groups having 2 to 3 carbon atoms, and they can be bonded together to form an aliphatic hydrocarbon ring.

[0163] At this time, in the above chemical formulas M-1 to M-6, the alkoxyalkyl group having 2 to 10 carbon atoms is, for example, R j2 -OR j1 It can be indicated as -*(* is the connection site). In this case, R j1 and R j2 The groups may independently be alkyl groups having 1 to 5 carbon atoms, and specifically, may independently be methyl groups, ethyl groups, propyl groups, butyl groups, or pentyl groups.

[0164] For example, the compound represented by the above formula M-1 may include at least one selected from the group consisting of compounds represented by the following formulas M-1-1 to M-1-10.

[0165] [Chemical Formula M-1-1]

[0166]

[0167] [Chemical Formula M-1-2]

[0168]

[0169] [Chemical Formula M-1-3]

[0170]

[0171] [Chemical Formula M-1-4]

[0172]

[0173] [Chemical Formula M-1-5]

[0174]

[0175] [Chemical Formula M-1-6]

[0176]

[0177] [Chemical Formula M-1-7]

[0178]

[0179] [Chemical Formula M-1-8]

[0180]

[0181] [Chemical Formula M-1-9]

[0182]

[0183] [Chemical Formula M-1-10]

[0184]

[0185] The compound represented by the above chemical formula M-2 may be at least one selected from the group consisting of compounds represented by the following chemical formulas M-2-1 to M-2-3.

[0186] [Chemical Formula M-2-1]

[0187]

[0188] [Chemical Formula M-2-2]

[0189]

[0190] [Chemical Formula M-2-3]

[0191]

[0192] The compound represented by the above chemical formula M-3 may be at least one selected from the group consisting of compounds represented by the following chemical formulas M-3-1 to M-3-6.

[0193] [Chemical Formula M-3-1]

[0194]

[0195] [Chemical Formula M-3-2]

[0196]

[0197] [Chemical Formula M-3-3]

[0198]

[0199] [Chemical Formula M-3-4]

[0200]

[0201] [Chemical Formula M-3-5]

[0202]

[0203] [Chemical Formula M-3-6]

[0204]

[0205] The compound represented by the above chemical formula M-4 may be at least one selected from the group consisting of compounds represented by the following chemical formulas M-4-1 to M-4-17.

[0206] [Chemical Formula M-4-1]

[0207]

[0208] [Chemical Formula M-4-2]

[0209]

[0210] [Chemical Formula M-4-3]

[0211]

[0212] [Chemical Formula M-4-4]

[0213]

[0214] [Chemical Formula M-4-5]

[0215]

[0216] [Chemical Formula M-4-6]

[0217]

[0218] [Chemical Formula M-4-7]

[0219]

[0220] [Chemical Formula M-4-8]

[0221]

[0222] [Chemical Formula M-4-9]

[0223]

[0224] [Chemical Formula M-4-10]

[0225]

[0226] [Chemical Formula M-4-11]

[0227]

[0228] [Chemical Formula M-4-12]

[0229]

[0230] [Chemical Formula M-4-13]

[0231]

[0232] [Chemical Formula M-4-14]

[0233]

[0234] [Chemical Formula M-4-15]

[0235]

[0236] [Chemical Formula M-4-16]

[0237]

[0238] [Chemical Formula M-4-17]

[0239]

[0240] The compound represented by the above chemical formula M-5 may be at least one selected from the group consisting of compounds represented by the following chemical formulas M-5-1 to M-5-14.

[0241] [Chemical Formula M-5-1]

[0242]

[0243] [Chemical Formula M-5-2]

[0244]

[0245] [Chemical Formula M-5-3]

[0246]

[0247] [Chemical Formula M-5-4]

[0248]

[0249] [Chemical Formula M-5-5]

[0250]

[0251] [Chemical Formula M-5-6]

[0252]

[0253] [Chemical Formula M-5-7]

[0254]

[0255] [Chemical Formula M-5-8]

[0256]

[0257] [Chemical Formula M-5-9]

[0258]

[0259] [Chemical Formula M-5-10]

[0260]

[0261] [Chemical Formula M-5-11]

[0262]

[0263] [Chemical Formula M-5-12]

[0264]

[0265] [Chemical Formula M-5-13]

[0266]

[0267] [Chemical Formula M-5-14]

[0268]

[0269] The compound represented by the above chemical formula M-6 may be at least one selected from the group consisting of compounds represented by the following chemical formulas M-6-1 to M-6-11.

[0270] [Chemical Formula M-6-1]

[0271]

[0272] [Chemical Formula M-6-2]

[0273]

[0274] [Chemical Formula M-6-3]

[0275]

[0276] [Chemical Formula M-6-4]

[0277]

[0278] [Chemical Formula M-6-5]

[0279]

[0280] [Chemical Formula M-6-6]

[0281]

[0282] [Chemical Formula M-6-7]

[0283]

[0284] [Chemical Formula M-6-8]

[0285]

[0286] [Chemical Formula M-6-9]

[0287]

[0288] [Chemical Formula M-6-10]

[0289]

[0290] [Chemical Formula M-6-11]

[0291]

[0292] In the above chemical formula 1, if M is a metal cation, a is the valence of M. For example, in the case of the alkali metal Li, a is 1, and in the case of the alkaline earth metal Ca, a is 2. If M is an organic cation, a is 1. In the above chemical formula 1, a=b.

[0293] More specifically, the compound represented by the above chemical formula 1 may be a compound represented by the following chemical formula 1-A.

[0294] [Chemical Formula 1-A]

[0295]

[0296] In the above chemical formula 1-A, M, a, n, and m are as defined in the above chemical formula 1.

[0297] More specifically, the compound represented by the above chemical formula 1 may be a compound represented by the following chemical formula 1-1.

[0298] [Chemical Formula 1-1]

[0299]

[0300] The coating layer may contain 100% by weight or less of the compound represented by Chemical Formula 1. Alternatively, the coating layer may contain 10 μg / cm² of the compound represented by Chemical Formula 1 per coating layer area. 2 to 30 μg / cm² 2 It may contain the compound represented by Chemical Formula 1 in an amount of 10 μg / cm² per coating layer area. 2 Above, 12 μg / cm² 2 Above, 13μg / cm² 2 Above, 14μg / cm² 2 Above, 17 μg / cm² 2 Above, or 20 μg / cm² 2 It may contain the above amount. The coating layer may contain the compound represented by Chemical Formula 1 at 30 μg / cm² per coating layer area. 2 Below, 29 μg / cm² 2 Below, 28 μg / cm² 2 Below, 27 μg / cm² 2 Below, 24 μg / cm² 2 ≤ or 23 μg / cm³2 It may be included in the following amounts. Each of the above ranges may be combined with one another. Alternatively, the coating layer may consist only of the compound represented by Chemical Formula 1, or, in addition to the compound represented by Chemical Formula 1, electrode film components derived from the non-aqueous electrolyte may be included in the remainder.

[0301] The compound represented by the above chemical formula 1 is, for example, after extracting a coating layer component from an electrode, 1 It can be confirmed through H-NMR.

[0302] In the present invention, in the counts-binding energy graph according to XPS analysis of the coating layer, peaks may be found at 401 eV to 395 eV; and 172 eV to 168 eV.

[0303] Specifically, the peak at 401 eV to 395 eV may be a peak indicating the presence of an inorganic film component such as Li3N, and the peak at 172 eV to 168 eV may be a peak indicating the presence of a film component such as sulfate.

[0304] As a precursor of the compound represented by the above chemical formula 1, at least one selected from the group consisting of ethylene sulfate and propylene sulfate as a first precursor and [M as a second precursor a+ ] p [NO3] q and [M a+ ] r [NO2] sAt least one selected from the group consisting of (wherein M is defined in Chemical Formula 1 above and satisfies the relationship a×p=q and a×r=s), specifically, at least one selected from the group consisting of LiNO3, NaNO3, LiNO2, and NaNO3. By adding the first precursor and the second precursor in appropriate amounts as additives to the non-aqueous electrolyte, the elemental ratio of sulfur (S) to nitrogen (N), the elemental ratio of sulfur (S) to carbon (C), and the elemental ratio of nitrogen (N) to carbon (C) in the coating layer can be realized.

[0305]

[0306] (2) bipolar

[0307] The above anode can be opposite to the above cathode.

[0308] The above anode may include an anode active material.

[0309] The above-mentioned cathode active material is a compound capable of reversible intercalation and deintercalation, and is not particularly limited as long as it is a cathode active material used in the field; specifically, it may include a lithium metal composite oxide. More specifically, the lithium metal composite oxide is a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; lithium iron oxide such as LiFe3O4; lithium iron phosphate such as LiFePO4; and a compound with the chemical formula Li 1+c1 Mn 2-c1 Lithium manganese oxides such as O4 (0≤c1≤0.33), LiMnO3, LiMn2O3, LiMnO2, etc.; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7, etc.; chemical formula LiNi 1-c2 M c2Ni-site type lithium nickel oxide represented by O2 (wherein M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, satisfying 0.01≤c2≤0.3); chemical formula LiMn 2-c3 M c3 Examples include lithium manganese composite oxides represented by O2 (where M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn, and Ta, satisfying 0.01 ≤ c3 ≤ 0.1) or Li2Mn3MO8 (where M is at least one selected from the group consisting of Fe, Co, Ni, Cu, and Zn); but are not limited thereto. The above-mentioned cathode may also be a Li-metal cathode. Meanwhile, the above-mentioned cathode active material may be a cathode active material of a lithium-sulfur battery, and the cathode active material may include S8, a composite of S8 and carbon, and Li x S(0 <x≤2)로 표시되는 황화 리튬 또는 황화 리튬과 탄소의 복합체일 수 있다.

[0310] More specifically, the positive electrode active material may include at least one selected from the group consisting of lithium cobalt oxide (LiCoO2), lithium nickel-cobalt-manganese oxide, lithium-rich manganese oxide, and lithium iron phosphate. More specifically, the positive electrode active material may include lithium iron phosphate.

[0311] The above lithium nickel-cobalt-manganese oxide can be represented by the following chemical formula P-1.

[0312] [Chemical Formula P-1]

[0313] Li 1+x (Ni a Co b Mn c M d )O2

[0314] In the above chemical formula P-1, M is one or more selected from 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 1+x, a, b, c, and d are each atomic fractions of independent elements, where 0≤x≤0.2, 0.50≤a<1, 0 <b≤0.25, 0<c≤0.25, 0≤d≤0.1, a+b+c+d=1이다. 바람직하게는, 상기 a, b, c 및 d는 각각 0.70≤a≤0.95, 0.025≤b≤0.20, 0.025≤c≤0.20, 0≤d≤0.05일 수 있다. 또한, 상기 a, b, c 및 d는 각각 0.80≤a≤0.95, 0.025≤b≤0.15, 0.025≤c≤0.15, 0≤d≤0.05일 수 있다. 또한, 상기 a, b, c 및 d는 각각 0.85≤a≤0.90, 0.05≤b≤0.10, 0.05≤c≤0.10, 0≤d≤0.03일 수 있다.

[0315] The above-mentioned lithium manganese-rich oxide may include a compound represented by the following chemical formula P-2.

[0316] [Chemical Formula P-2]

[0317] Li 1+s [Ni t Co u Mn v M 1 w ]O 2+z

[0318] In the above chemical formula P-2, M 1... is one or more selected from 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 0.05≤s≤1, 0≤t≤0.5, 0≤u≤0.3, 0.5≤v<1.0, 0≤w≤0.2, 0≤z≤1. Preferably, in the above formula B, 0.05≤s≤1.0, 0.1≤t≤0.5, 0≤u≤0.1, 0.5≤v<1.0, 0≤w≤0.2, 0≤z≤1. More preferably, in the above formula P-2, 0.10≤s≤0.50, 0.1≤t≤0.5, 0≤u≤0.1, 0.6≤v<1.0, 0≤w≤0.1, and 0≤z≤0.50.

[0319] The above lithium iron phosphate may include a compound represented by the following chemical formula P-3.

[0320] [Chemical Formula P-3]

[0321] Li 1+e Fe 1-g M 2 g (PO 4-f )X f

[0322] In the above chemical formula P-3, M 2 is one or more elements selected from Co, Ni, Mn, Al, Mg, Ti, and V, X is F, S, or N, and 0≤g≤0.5; -0.5≤e≤+0.5; 0≤f≤0.1. The above chemical formula P-3 can be specifically represented as LiFePO4 (g=0, e=0, and f=0).

[0323] The above positive active material may be in the form of particles. Specifically, the average particle size (D) of the above positive active material 50 ) can be 1㎛ to 30㎛.

[0324] The above positive active material may be included in the positive active material layer in an amount of 70% to 99% by weight, specifically 80% to 98% by weight, for capacity enhancement.

[0325]

[0326] The above positive electrode may include a positive current collector; and a positive active material layer disposed on at least one surface of the positive current collector. In this case, the positive active material layer may include the aforementioned positive active material.

[0327] The thickness of the above positive current collector can typically be 3 to 500 μm.

[0328] The above positive current collector may form fine irregularities on its surface to strengthen the bonding force of the positive active material. For example, the above positive current collector can be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0329] The positive active material layer is disposed on at least one surface of the positive current collector. Specifically, the positive active material layer may be disposed on one or both surfaces of the positive current collector.

[0330] The above positive active material may be included in the positive active material layer in an amount of 80% to 99% by weight, taking into account the sufficient capacity exertion of the positive active material.

[0331] The above positive active material layer may further include a binder and / or a conductive material together with the aforementioned positive active material.

[0332] The above binder is a component that assists in the binding of active materials and conductive materials, and in binding to current collectors, and specifically may include at least one selected from the group consisting of polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene, polyethylene, polypropylene, ethylene-propylene-diene ter polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, and fluororubber, preferably polyvinylidene fluoride.

[0333] The above binder may be included in the positive active material layer in an amount of 1% to 20% by weight, preferably 1.2% to 10% by weight, in order to sufficiently secure binding strength between components such as the positive active material.

[0334] The above conductive material can be used to assist and enhance conductivity in a secondary battery, and is not particularly limited as long as it is conductive without causing chemical changes. Specifically, the above cathode conductive material may include at least one selected from the group consisting of graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, ketjen black, channel black, Farnes black, lamp black, thermal black; conductive fibers such as carbon fibers or metal fibers; conductive tubes such as carbon nanotubes; fluorocarbons; metal powders such as aluminum or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and polyphenylene derivatives, and preferably may include carbon nanotubes for the purpose of enhancing conductivity.

[0335] The above conductive material may be included in the above positive active material layer in an amount of 1% to 20% by weight, preferably 1.2% to 10% by weight, in order to sufficiently ensure electrical conductivity.

[0336] The thickness of the above positive active material layer may be 5㎛ to 500㎛, preferably 20㎛ to 200㎛.

[0337] The anode may be manufactured by coating an anode slurry comprising an anode active material and optionally a binder, a conductive material, and a solvent for forming an anode slurry onto the anode current collector, and then drying and rolling. Alternatively, the anode may be manufactured by mixing an anode active material and optionally a binder, a conductive material, etc. to produce a film, and then laminating it onto an anode current collector.

[0338] The solvent for forming the anode slurry may include, for example, at least one selected from the group consisting of distilled water, N-methylpyrrolidone, ethanol, methanol, and isopropyl alcohol, preferably N-methylpyrrolidone, in order to facilitate the dispersion of the anode active material, binder, and / or conductive material.

[0339]

[0340] (3) Separator

[0341] The above separator separates the negative and positive electrodes and provides a pathway for the movement of lithium ions. It can be used without any specific restrictions as long as it is typically used as a separator in a lithium secondary battery, and it is particularly desirable that it has low resistance to the movement of ions of a non-aqueous electrolyte and excellent moisture retention capacity for the non-aqueous electrolyte.

[0342] Specifically, as a separator, a porous polymer film made of a polyolefin-based polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, or an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof may be used. In addition, a conventional porous nonwoven fabric, such as a nonwoven fabric made of high-melting-point glass fibers or polyethylene terephthalate fibers, may be used. Furthermore, a coated separator containing a ceramic component or a polymer material may be used to ensure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

[0343]

[0344] (4) Non-aqueous electrolyte

[0345] The above lithium secondary battery contains a non-aqueous electrolyte.

[0346] The above-mentioned non-aqueous electrolyte may include a lithium salt and an organic solvent. In some cases, the above-mentioned non-aqueous electrolyte may include a lithium salt, an organic solvent, and an additive.

[0347]

[0348] 1) Lithium salt

[0349] As the lithium salt used in the present invention, various lithium salts commonly used in non-aqueous electrolytes for lithium secondary batteries may be used without limitation. For example, the lithium salt is Li as a cation. + It includes, and as anion, F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO2 - , AlO4 - , AlCl4 - , PF6 - , SbF6 - , AsF6 - , B 10 Cl 10 - , BF2C2O4 - , BC4O8 - , PF4C2O4 - , PF2C4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , C4F9SO3 - , CF3CF2SO3 - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , CH3SO3 - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - It may include at least one selected from a group consisting of

[0350] Specifically, the lithium salt is LiCl, LiBr, LiI, LiBF4, LiClO4, LiAlO2, LiAlO4, LiAlCl4, LiPF6, LiSbF6, LiAsF6, LiB 10 Cl 10 It may include at least one selected from the group consisting of LiBOB (LiB(C2O4)2), LiCF3SO3, LiFSI (LiN(SO2F)2), LiCH3SO3, LiCF3CO2, LiCH3CO2, and LiBETI (LiN(SO2CF2CF3)2). Specifically, the lithium salt may include at least one selected from the group consisting of LiBF4, LiClO4, LiPF6, LiBOB (LiB(C2O4)2), LiCF3SO3, LiTFSI (LiN(SO2CF3)2), LiFSI (LiN(SO2F)2), and LiBETI (LiN(SO2CF2CF3)2).

[0351] The above lithium salt may be included in the above-mentioned non-aqueous electrolyte at a concentration of 0.5M to 5M, specifically 0.8M to 4M, and more specifically 0.8M to 2.5M. When the concentration of the above-mentioned lithium salt satisfies the above range, the lithium ion yield (Li + The transference number and the degree of dissociation of lithium ions are improved, which can enhance the output characteristics of the battery.

[0352] Alternatively, the above lithium salt may be included in the non-aqueous electrolyte in the remainder excluding, for example, the organic solvent and additives described below.

[0353]

[0354] 2) Organic solvent

[0355] The above organic solvent is a non-aqueous solvent commonly used in lithium secondary batteries, and is not particularly limited as long as it minimizes decomposition due to oxidation reactions, etc., during the charging and discharging process of the secondary battery.

[0356] The above organic solvent may be included in the non-aqueous electrolyte in the remainder excluding lithium salts and additives, for example.

[0357] Specifically, the organic solvent may include a carbonate-based organic solvent. Specifically, the carbonate-based organic solvent may include at least one selected from a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent, and more specifically, may include a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent.

[0358] More specifically, the cyclic carbonate-based organic solvent is a high-viscosity organic solvent that has a high dielectric constant and can effectively dissociate lithium salts in the electrolyte. Specifically, it may include at least one organic solvent selected from the group consisting of ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate. More specifically, it may include at least one selected from the group consisting of ethylene carbonate (EC) and fluoroethylene carbonate (FEC), and even more specifically, it may include ethylene carbonate (EC).

[0359] In addition, the linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, and specifically may include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethylmethyl carbonate (EMC), methylpropyl carbonate (MPC), and ethylpropyl carbonate (EPC); more specifically, may include at least one selected from the group consisting of ethylmethyl carbonate and dimethyl carbonate; and even more specifically, may include ethylmethyl carbonate and dimethyl carbonate.

[0360] When the above carbonate-based organic solvent comprises a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent, the weight ratio of the cyclic carbonate-based organic solvent and the linear carbonate-based organic solvent may be 10:90 to 50:50, specifically 15:85 to 45:55, more specifically 15:85 to 40:60, and even more specifically 20:80 to 40:60.

[0361]

[0362] The above organic solvent may further include at least one of an ester-based organic solvent, an ether-based organic solvent, a glycine-based solvent, and a nitrile-based organic solvent together with the above carbonate-based organic solvent.

[0363] The above ester-based organic solvent may include at least one selected from linear ester-based organic solvents and cyclic ester-based organic solvents. Specifically, the above linear ester-based organic solvent may include at least one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate. Additionally, the above cyclic ester-based organic solvent may specifically include at least one selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0364] As the above ether-based solvent, any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methylpropyl ether, ethyl propyl ether, 1,3-dioxolane (DOL), and 2,2-bis(trifluoromethyl)-1,3-dioxolane (TFDOL), or a mixture of two or more of these may be used, but is not limited thereto.

[0365] The above-mentioned glyme-based solvent has a high dielectric constant and low surface tension compared to linear carbonate-based organic solvents and is a solvent with low reactivity with metals. It may include at least one selected from the group consisting of dimethoxyethane (glyme, DME), diethoxyethane, diglyme, triglyme, and tetraglyme (TEGDME), but is not limited thereto.

[0366] The above nitrile-based solvent may be one or more selected from the group consisting of acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile, but is not limited thereto.

[0367]

[0368] The above organic solvent may consist solely of the carbonate-based organic solvent. Even if only the carbonate-based organic solvent is used as the organic solvent, it is preferable in that it facilitates the dissolution of non-aqueous electrolyte components, such as the additives described later, and enables the realization of appropriate mobility of the lithium salt and viscosity of the non-aqueous electrolyte.

[0369]

[0370] 3) Additives

[0371] The above additive may be included as needed to prevent the decomposition of the electrolyte in a high-power environment from causing cathode breakdown, or to further improve low-temperature high-rate discharge characteristics, high-temperature stability, prevention of overcharging, and suppression of battery expansion at high temperatures.

[0372] Specifically, the above additive may include a compound represented by the following chemical formula 2.

[0373] [Chemical Formula 2]

[0374]

[0375] In the above chemical formula 2, R1 is -O-NO2, L1 is an alkyleneoxy group having 1 to 5 carbon atoms, M is a metal cation or an organic cation, a is the valence of M when M is a metal cation, 1 when M is an organic cation, and a=b.

[0376] The compound represented by Chemical Formula 2 above includes a salt-type compound containing an organosulfonyl group, nitrogen, and oxygen, thereby forming a film on the positive / negative electrode surface that is highly durable and capable of reducing resistance. The compound represented by Chemical Formula 2 above contains an organosulfonyl group within its structure, and thus undergoes reductive decomposition before the organic solvent during charging and discharging. Consequently, a solid-electrolyte interface layer containing lithium sulfide and lithium sulfate, which is excellent in terms of ion conductivity, is uniformly formed on the negative electrode surface. This allows it to function as an effective ion carrier, thereby suppressing the degradation of the negative and positive electrodes. Furthermore, since the solid-electrolyte interface layer derived from the functional group has excellent durability, the deterioration of the solid-electrolyte interface layer and the resulting problem of transition metal leaching from the positive electrode can be prevented. In addition, the compound represented by Chemical Formula 2 included as the additive contains nitrogen as an anionic terminal group within its structure, and can form a solid-electrolyte interface layer containing lithium nitride, lithium nitrate, lithium oxide, etc., on the surface of the cathode. This can improve the lithium ion diffusion within the solid-electrolyte interface layer, thereby reducing resistance and minimizing reversible lithium ion loss due to excellent high-temperature durability. Furthermore, it can effectively suppress the leaching of transition metals from the cathode by preventing side reactions between the electrolyte and the cathode. The compound represented by Chemical Formula 2 can effectively protect the electrode in environments where side reactions of the electrolyte, cathode breakdown, or destruction of the SEI film on the cathode are likely to occur, such as at high temperatures and high voltages. Accordingly, the lifespan and storage performance of the lithium secondary battery, particularly under high temperatures and high voltages, can be significantly improved. In other words, the compound represented by Chemical Formula 1 is desirable in that it can achieve the combined effect of improving the output performance, lifespan performance, and storage performance of the lithium secondary battery.

[0377] In addition, the compound represented by the above chemical formula 2 is also desirable in that it can easily realize the elemental ratio of sulfur (S) to nitrogen (N), the elemental ratio of sulfur (S) to carbon (C), and the elemental ratio of nitrogen (N) to carbon (C) of the aforementioned coating layer.

[0378] The compound represented by Chemical Formula 2 above may be included in the non-aqueous electrolyte in an amount of 0.25% to 1.60% by weight. The compound represented by Chemical Formula 2 above may be included in an amount of 0.25% to 1.60% by weight based on the total weight of the non-aqueous electrolyte. Specifically, the compound represented by Chemical Formula 2 above may be included in the non-aqueous electrolyte in an amount of 0.25% or more by weight, 0.28% or more by weight, 0.30% or more by weight, 0.40% or more by weight, 0.50% or more by weight, 0.60% or more by weight, 0.70% or more by weight, 0.80% or more by weight, 0.90% or more by weight, 1.0% or more by weight, 1.20% or more by weight, 1.30% or more by weight, 1.40% or more by weight, or 1.45% or more by weight. The compound represented by Chemical Formula 2 above may be included in the non-aqueous electrolyte in an amount of 1.60 wt% or less, 1.50 wt% or less, 1.45 wt% or less, 1.40 wt% or less, 1.30 wt% or less, 1.20 wt% or less, 1.10 wt% or less, 1.0 wt% or less, 0.90 wt% or less, 0.80 wt% or less, 0.70 wt% or less, 0.60 wt% or less, 0.50 wt% or less, 0.40 wt% or less, or 0.35 wt% or less. The above ranges may be combined with each other without limitation. Within the aforementioned range, a robust inorganic film containing lithium-nitrogen, lithium-oxygen, and lithium-sulfur bonds is uniformly formed on the surfaces of the anode and cathode while minimizing disadvantages such as side reactions caused by additives, capacity degradation, and increased resistance. This allows the film to function effectively as an ion carrier, effectively suppress the leaching of transition metals from the anode, and effectively suppress side reactions between the electrolyte and the electrode, thereby enabling excellent high-temperature durability and low-temperature output performance. Furthermore, within the above range, it is also desirable in that the elemental ratio of sulfur (S) to nitrogen (N), the elemental ratio of sulfur (S) to carbon (C), and the elemental ratio of nitrogen (N) to carbon (C) in the aforementioned coating layer can be easily realized.

[0379]

[0380] In the above chemical formula 2, M can be a metal cation or an organic cation.

[0381] Specifically, when M is a metal cation, M may be any one selected from the group consisting of Li, K, Ca, Mg, and Cs, and, for example, may be Li.

[0382] In addition, if M is an organic cation (i.e., a cation in the form of an organic compound), M may be any one selected from the group consisting of compounds represented by the following chemical formulas M-1 to M-6.

[0383] [Chemical Formula M-1]

[0384]

[0385] In the above chemical formula M-1, X M1 is -N(R M15 )- or -S- and, R M11 , R M12 , R M13 , R M14 and R M15 may independently be hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. Specifically, R M11 , R M12 , R M13 , R M14 and R M15 s⁻¹ may independently be hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 5 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. More specifically, in the above formula M-1, R⁻¹ M11 , R M12 , RM13 , R M14 and R M15 The groups may independently be hydrogen, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, allyl group (*-CH2CH=CH2), phenyl group, cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, 4-cyanobutyl group, methoxymethyl group, 2-methoxyethyl group, 3-methoxypropyl group, methoxy group, or ethoxy group.

[0386] [Chemical Formula M-2]

[0387]

[0388] In the above chemical formula M-2, X M2 is -N(R M25 )- or -S- is. R M21 , R M22 , R M23 , R M24 and R M25 may independently be hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 2 to 12 carbon atoms. Specifically, R M21 , R M22 , R M23 , R M24 and R M25 may independently be hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 5 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. More specifically, in the above formula M-2, R M21 , R M22 , R M23 , R M24 and R M25The groups may independently be hydrogen, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, allyl group (*-CH2CH=CH2), phenyl group, cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, 4-cyanobutyl group, methoxymethyl group, 2-methoxyethyl group, 3-methoxypropyl group, ethoxymethyl group, 2-ethoxyethyl group, 3-ethoxypropyl group, methoxy group, or ethoxy group.

[0389] [Chemical Formula M-3]

[0390]

[0391] In the above chemical formula M-3, R M31 , R M32 , R M33 , R M34 , R M35 and R M36 may independently be hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. Specifically, R M31 , R M32 , R M33 , R M34 , R M35 and R M36 may independently be hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 5 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. More specifically, R M31 , R M32 , R M33 , R M34 , R M35 and R M36The groups may independently be hydrogen, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, allyl group (*-CH2CH=CH2), phenyl group, cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, 4-cyanobutyl group, methoxymethyl group, 2-methoxyethyl group, 3-methoxypropyl group, ethoxymethyl group, 2-ethoxyethyl group, 3-ethoxypropyl group, methoxy group, or ethoxy group.

[0392] [Chemical Formula M-4]

[0393]

[0394] In the above chemical formula M-4, R M41 , R M42 , R M43 and R M44 may independently be hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. Specifically, R M41 , R M42 , R M43 and R M44 may independently be hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 5 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. More specifically, R M41 , R M42 , R M43 and R M44may independently be hydrogen, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, allyl group (*-CH2CH=CH2), phenyl group, cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, 4-cyanobutyl group, methoxymethyl group, 2-methoxyethyl group, 3-methoxypropyl group, ethoxymethyl group, 2-ethoxyethyl group, 3-ethoxypropyl group, methoxy group, or ethoxy group. Additionally, R M41 , R M42 , R M43 and R M44 At least two of these types may combine to form an aliphatic ring, specifically R M41 , R M42 , R M43 and R M44 At least two of them are alkyl groups having 1 to 5 carbon atoms or alkyl groups having 2 to 3 carbon atoms, and they can be bonded together to form an aliphatic hydrocarbon ring.

[0395] [Chemical Formula M-5]

[0396]

[0397] In the above chemical formula M-5, R M51 , R M52 , R M53 and R M54 may independently be hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. Specifically, R M51 , R M52 , R M53 and R M54may independently be hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 5 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. More specifically, R M51 , R M52 , R M53 and R M54 may independently be hydrogen, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, allyl group (*-CH2CH=CH2), phenyl group, cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, 4-cyanobutyl group, methoxymethyl group, 2-methoxyethyl group, 3-methoxypropyl group, ethoxymethyl group, 2-ethoxyethyl group, 3-ethoxypropyl group, methoxy group, or ethoxy group. Additionally, R M51 , R M52 , R M53 and R M54 At least two of these types may combine to form an aliphatic ring, specifically R M51 , R M52 , R M53 and R M54 At least two of them are alkyl groups having 1 to 5 carbon atoms or alkyl groups having 2 to 3 carbon atoms, and they can be bonded together to form an aliphatic hydrocarbon ring.

[0398] [Chemical Formula M-6]

[0399]

[0400] In the above chemical formula M-6, R M61 , R M62 and R M63may independently be hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. Specifically, R M61 , R M62 and R M63 is independently hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 5 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. More specifically, R M61 , R M62 and R M63 may independently be hydrogen, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, allyl group (*-CH2CH=CH2), phenyl group, cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, 4-cyanobutyl group, methoxymethyl group, 2-methoxyethyl group, 3-methoxypropyl group, ethoxymethyl group, 2-ethoxyethyl group, 3-ethoxypropyl group, methoxy group, or ethoxy group. Additionally, R M61 , R M62 and R M63 At least two of these types may combine to form an aliphatic ring, specifically R M61 , R M62 and R M63 At least two of them are alkyl groups having 1 to 5 carbon atoms or alkyl groups having 2 to 3 carbon atoms, and they can be bonded together to form an aliphatic hydrocarbon ring.

[0401] At this time, in the above chemical formulas M-1 to M-6, the alkoxyalkyl group having 2 to 10 carbon atoms is, for example, R j2 -OR j1 It can be indicated as -*(* is the connection site). In this case, Rj1 and R j2 The groups may independently be alkyl groups having 1 to 5 carbon atoms, and specifically, may independently be methyl groups, ethyl groups, propyl groups, butyl groups, or pentyl groups.

[0402] For example, the compound represented by the above formula M-1 may include at least one selected from the group consisting of compounds represented by the following formulas M-1-1 to M-1-10.

[0403] [Chemical Formula M-1-1]

[0404]

[0405] [Chemical Formula M-1-2]

[0406]

[0407] [Chemical Formula M-1-3]

[0408]

[0409] [Chemical Formula M-1-4]

[0410]

[0411] [Chemical Formula M-1-5]

[0412]

[0413] [Chemical Formula M-1-6]

[0414]

[0415] [Chemical Formula M-1-7]

[0416]

[0417] [Chemical Formula M-1-8]

[0418]

[0419] [Chemical Formula M-1-9]

[0420]

[0421] [Chemical Formula M-1-10]

[0422]

[0423] The compound represented by the above chemical formula M-2 may be at least one selected from the group consisting of compounds represented by the following chemical formulas M-2-1 to M-2-3.

[0424] [Chemical Formula M-2-1]

[0425]

[0426] [Chemical Formula M-2-2]

[0427]

[0428] [Chemical Formula M-2-3]

[0429]

[0430] The compound represented by the above chemical formula M-3 may be at least one selected from the group consisting of compounds represented by the following chemical formulas M-3-1 to M-3-6.

[0431] [Chemical Formula M-3-1]

[0432]

[0433] [Chemical Formula M-3-2]

[0434]

[0435] [Chemical Formula M-3-3]

[0436]

[0437] [Chemical Formula M-3-4]

[0438]

[0439] [Chemical Formula M-3-5]

[0440]

[0441] [Chemical Formula M-3-6]

[0442]

[0443] The compound represented by the above chemical formula M-4 may be at least one selected from the group consisting of compounds represented by the following chemical formulas M-4-1 to M-4-17.

[0444] [Chemical Formula M-4-1]

[0445]

[0446] [Chemical Formula M-4-2]

[0447]

[0448] [Chemical Formula M-4-3]

[0449]

[0450] [Chemical Formula M-4-4]

[0451]

[0452] [Chemical Formula M-4-5]

[0453]

[0454] [Chemical Formula M-4-6]

[0455]

[0456] [Chemical Formula M-4-7]

[0457]

[0458] [Chemical Formula M-4-8]

[0459]

[0460] [Chemical Formula M-4-9]

[0461]

[0462] [Chemical Formula M-4-10]

[0463]

[0464] [Chemical Formula M-4-11]

[0465]

[0466] [Chemical Formula M-4-12]

[0467]

[0468] [Chemical Formula M-4-13]

[0469]

[0470] [Chemical Formula M-4-14]

[0471]

[0472] [Chemical Formula M-4-15]

[0473]

[0474] [Chemical Formula M-4-16]

[0475]

[0476] [Chemical Formula M-4-17]

[0477]

[0478] The compound represented by the above chemical formula M-5 may be at least one selected from the group consisting of compounds represented by the following chemical formulas M-5-1 to M-5-14.

[0479] [Chemical Formula M-5-1]

[0480]

[0481] [Chemical Formula M-5-2]

[0482]

[0483] [Chemical Formula M-5-3]

[0484]

[0485] [Chemical Formula M-5-4]

[0486]

[0487] [Chemical Formula M-5-5]

[0488]

[0489] [Chemical Formula M-5-6]

[0490]

[0491] [Chemical Formula M-5-7]

[0492]

[0493] [Chemical Formula M-5-8]

[0494]

[0495] [Chemical Formula M-5-9]

[0496]

[0497] [Chemical Formula M-5-10]

[0498]

[0499] [Chemical Formula M-5-11]

[0500]

[0501] [Chemical Formula M-5-12]

[0502]

[0503] [Chemical Formula M-5-13]

[0504]

[0505] [Chemical Formula M-5-14]

[0506]

[0507] The compound represented by the above chemical formula M-6 may be at least one selected from the group consisting of compounds represented by the following chemical formulas M-6-1 to M-6-11.

[0508] [Chemical Formula M-6-1]

[0509]

[0510] [Chemical Formula M-6-2]

[0511]

[0512] [Chemical Formula M-6-3]

[0513]

[0514] [Chemical Formula M-6-4]

[0515]

[0516] [Chemical Formula M-6-5]

[0517]

[0518] [Chemical Formula M-6-6]

[0519]

[0520] [Chemical Formula M-6-7]

[0521]

[0522] [Chemical Formula M-6-8]

[0523]

[0524] [Chemical Formula M-6-9]

[0525]

[0526] [Chemical Formula M-6-10]

[0527]

[0528] [Chemical Formula M-6-11]

[0529]

[0530] In Chemical Formula 2 above, if M is a metal cation, a is the valence of M. For example, in the case of the alkali metal Li, a is 1, and in the case of the alkaline earth metal Ca, a is 2. If M is an organic cation, a is 1. In Chemical Formula 1 above, a=b.

[0531] For example, the compound represented by the above chemical formula 2 may include the compound represented by the following chemical formula 2-1.

[0532] [Chemical Formula 2-1]

[0533]

[0534] In the above chemical formula 2-1, M, a, b, and L1 are as defined in the above chemical formula 1.

[0535] In the above Chemical Formula 2, L1 may be an alkyleneoxy group having 1 to 5 carbon atoms. For example, L1 is -OR L1 -It could be, R L1 ... may be an alkylene group having 1 to 5 carbon atoms. In this case, L1 is an alkyleneoxy group (e.g., -OR L1 In the case of -), oxygen (O) may be bonded to sulfur (S). L1 may specifically be an alkyleneoxy group having 2 to 3 carbon atoms, more specifically an ethyleneoxy group or a propyleneoxy group, and even more specifically an ethyleneoxy group.

[0536]

[0537] Specifically, the compound represented by the above chemical formula 2 may include the compound represented by the following chemical formula 2-A.

[0538] [Chemical Formula 2-A]

[0539]

[0540] In the above chemical formula 2-A, each of M, a, b, and R1 is as defined in the above chemical formula 2.

[0541] More specifically, the compound represented by the above chemical formula 2 may include the compound represented by the following chemical formula 2-A-1.

[0542] [Chemical Formula 2-A-1]

[0543]

[0544] In the above chemical formula 2-A-1, each of M, a, and b is as defined in the above chemical formula 1.

[0545]

[0546] More specifically, the compound represented by the above chemical formula 2 may include the compound represented by the following chemical formula 2-a-1.

[0547] [Chemical Formula 2-a-1]

[0548]

[0549]

[0550] The compound represented by the above chemical formula 2 may be formed, for example, by reacting a sulfur oxide (e.g., a cyclic sulfur oxide containing a sulfate group (-OS(=O)2-O-) within the ring) with a metal nitrate (e.g., lithium nitrate, lithium nitrite, etc.), but is not particularly limited thereto. This reaction may be carried out in advance before the manufacture of the non-aqueous electrolyte, or the aforementioned sulfur oxide and metal nitrate may be introduced into an organic solvent during the manufacture of the non-aqueous electrolyte.

[0551] The presence of the compound represented by the above Chemical Formula 2 is determined by HR-LS / MS (High Resolution Liquid Chromatography-Mass Spectrometry) and / or 1 It can be confirmed via H-NMR (H-Nuclear Magnetic Resonance Spectroscopy), but is not specifically limited to this.

[0552]

[0553] In the present invention, the additive may include at least one of the compound represented by Formula 2, ethylene sulfate, and 1,3-propane sulfone. That is, the non-aqueous electrolyte according to the present invention may optionally include ethylene sulfate and / or 1,3-propane sulfone together with the compound represented by Formula 2 as an additive. Alternatively, the non-aqueous electrolyte according to the present invention may include ethylene sulfate and / or 1,3-propane sulfone together with the compound represented by Formula 2 as an additive, or may include only the compound represented by Formula 2. The ethylene sulfate and / or 1,3-propane sulfone may be included in the additive as an auxiliary component for the formation of a sulfur (S)-containing SEI film.

[0554] The total content of the compound represented by Chemical Formula 2, ethylene sulfate, and 1,3-propane sulfone may be 0.25% to 1.60% by weight based on the total weight of the non-aqueous electrolyte. When the total content of the compound represented by Chemical Formula 2, ethylene sulfate, and 1,3-propane sulfone is within the above range, it is possible to form a uniform film, reduce resistance, and improve output performance. When the total content of the compound represented by Chemical Formula 2, ethylene sulfate, and 1,3-propane sulfone is within the above range, it is also desirable in that the elemental ratio of sulfur (S) to nitrogen (N), the elemental ratio of sulfur (S) to carbon (C), and the elemental ratio of nitrogen (N) to carbon (C) in the aforementioned coating layer can be easily realized.

[0555] In the present invention, the total content of the compound represented by Formula 2, ethylene sulfate, and 1,3-propanesulfone may mean, for example, the total content of the compound represented by Formula 2 and 1,3-propanesulfone in the non-aqueous electrolyte when the non-aqueous electrolyte does not contain ethylene sulfate, the total content of the compound represented by Formula 2 and ethylene sulfate in the non-aqueous electrolyte when the non-aqueous electrolyte does not contain 1,3-propanesulfone, and the content of the compound represented by Formula 2 when the non-aqueous electrolyte does not contain 1,3-propanesulfone and ethylene sulfate.

[0556] Specifically, the total content of the compound represented by Chemical Formula 2, ethylene sulfate, and 1,3-propane sulfone may be 0.75% to 1.60% by weight, 0.8% to 1.5% by weight, or 0.9% to 1.5% by weight based on the total weight of the non-aqueous electrolyte. Being within the aforementioned range is desirable in that it not only improves the uniformity of the electrode film but also enables stable battery performance through smooth diffusion of lithium ions.

[0557] If the additive contains ethylene sulfate, the ethylene sulfate may be 1% by weight or less, 0.9% by weight or less, 0.85% by weight or less, 0.81% by weight or less, 0.7% by weight or less, 0.6% by weight or less, or 0.1% by weight or less, based on the total weight of the non-aqueous electrolyte. If the additive contains ethylene sulfate, the ethylene sulfate may be greater than 0% by weight based on the total weight of the non-aqueous electrolyte. The additive may not contain ethylene sulfate.

[0558] If the additive contains 1,3-propane sulfone, the 1,3-propane sulfone may be 0.5 wt% or less, 0.3 wt% or less, 0.2 wt% or less, or 0.1 wt% or less based on the total weight of the non-aqueous electrolyte. If the additive contains 1,3-propane sulfone, the 1,3-propane sulfone may be greater than 0 wt% based on the total weight of the non-aqueous electrolyte. The additive may not contain 1,3-propane sulfone.

[0559] The above-mentioned non-aqueous electrolyte may additionally include auxiliary additives.

[0560] The above auxiliary additive may include at least one selected from the group consisting of cyclic carbonate compounds, nitrile compounds, benzene compounds, lithium salt compounds, amine compounds, and silane compounds.

[0561] The above cyclic carbonate compound may be at least one selected from vinylene carbonate (VC) and vinylethylene carbonate (VEC).

[0562] The above benzene-based compound may be fluorobenzene. The above amine-based compound may be at least one selected from triethanolamine and ethylenediamine. The above silane-based compound may be at least one selected from tetravinylsilane, tris(trimethylsilyl)phosphate (TMSPa), and tris(trimethylsilyl)phosphite (TMSPi). The above lithium salt-based additive may be at least one selected from lithium bis-(oxalato)borate (LiBOB), lithium difluorooxalatoborate (LiODFB), and lithium difluorophosphate (LiDFP).

[0563] The above nitrile compound may be at least one selected from the group consisting of succinonitrile, adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile.

[0564] Specifically, the auxiliary additive may include at least one selected from vinylene carbonate and fluoroethylene carbonate, and specifically may include vinylene carbonate and fluoroethylene carbonate.

[0565] Meanwhile, the above auxiliary additives may be used in a mixture of two or more types, and may be included in an amount of less than 10% by weight based on the total weight of the non-aqueous electrolyte, specifically 0.01% by weight or more and less than 8.0% by weight, more specifically 0.05% by weight to 5.0% by weight, and even more specifically 3% by weight to 5% by weight.

[0566]

[0567] In the present invention, a V - dQ / dV graph obtained by differentiating the graph of voltage V and battery capacity Q measured by performing a process including electrochemical charging on a lithium secondary battery including the electrode may have a peak at 1.0V to 2.0V.

[0568] In this specification, the term "peak" may be defined as the peak point in any peak region existing on a V-dQ / dV graph where the x-axis is the voltage (V) value and the y-axis is the dQ / dV value, specifically the point having the minimum dQ / dV value in said peak region. More specifically, any peak region existing on said V-dQ / dV graph may refer to a voltage region where a reduction reaction of a specific component present in a non-aqueous electrolyte occurs, and it may be understood that the reduction reaction of the specific component starts at the point where the peak region begins (the minimum voltage point of the peak region), the reduction reaction of the specific component occurs to the maximum at the peak point of the peak region, and the reduction reaction of the specific component ends at the point where the peak region ends (the maximum voltage point of the peak region). The area of ​​said peak region may refer to the amount of the reduction reaction of the specific component, and the width of the peak area may refer to the rate of the reduction reaction of the specific component.

[0569] The peak existing at 1.0V to 2.0V in the above V - dQ / dV graph may be derived from the reduction reaction of a compound represented by Chemical Formula 1. In the above V - dQ / dV graph, the peak existing at 1.0V to 2.0V may be distinguished from the peak existing at a position exceeding 2.0V derived from the reduction reaction of a compound that does not contain a sulfur-containing functional group in its structure, such as lithium nitrate; and the peak existing at a position exceeding 2.0V derived from the reduction reaction of cyclic sulfur oxides such as ethylene sulfate and 1,3-propanesulfone.

[0570] In deriving the above V - dQ / dV graph, the lithium secondary battery may be a lithium secondary battery comprising the above-described positive electrode, negative electrode, separator, and non-aqueous electrolyte, specifically in the form of a full-cell.

[0571] In addition to the above description, the components included in the lithium secondary battery for deriving the V - dQ / dV graph may be the same as those described in the lithium secondary battery described in the present invention.

[0572] In deriving the above V - dQ / dV graph, the process including the electrochemical charging performed may refer to the formation of the lithium secondary battery. That is, in deriving the above V - dQ / dV graph, the lithium secondary battery used may be an uncharged lithium secondary battery.

[0573] The charging conditions of the above lithium secondary battery are not particularly limited. For example, the above lithium secondary battery may be charged in a constant current / constant voltage (CC / CV) mode, and, for example, may be cut off at 0.05C and 0.05V when charged in a constant current / constant voltage (CC / CV) mode. When charging the above lithium secondary battery, it may be charged at a charging rate of 0.05C to 1C, specifically 0.1C to 0.5C. When charging the above lithium secondary battery, the SOC of the lithium secondary battery may be charged to 40% to 100%, specifically to 70% to 100%, and more specifically to 100%.

[0574] In the V - dQ / dV graph obtained by differentiating the graph of voltage V and battery capacity Q measured by charging the above lithium secondary battery, 1.0V or more, 1.02V or more, 1.05V or more, 1.07V or more, 1.1V or more, 1.12V or more, 1.15V or more, 1.17V or more, 1.2V or more, 1.22V or more, 1.25V or more, 1.27V or more, 1.3V or more, 1.32V or more, 1.35V or more, 1.37V or more, 1.4V or more, 1.42V or more, 1.45V or more, 1.47V or more, 1.5V or more, 1.52V or more, 1.55V or more, 1.57V or more, 1.6V or more, 1.62V or more, 1.65V or more, Peaks may exist at 1.67V or higher, 1.7V or higher, 1.72V or higher, 1.75V or higher, 1.77V or higher, 1.8V or higher, 1.82V or higher, 1.85V or higher, 1.87V or higher, or 1.9V or higher. In the V - dQ / dV graph obtained by differentiating the graph of voltage V and battery capacity Q measured by charging the above lithium secondary battery, 2.0V or less, 1.97V or less, 1.95V or less, 1.92V or less, 1.9V or less, 1.87V or less, 1.85V or less, 1.82V or less, 1.8V or less, 1.77V or less, 1.75V or less, 1.72V or less, 1.7V or less, 1.67V or less, 1.65V or less, 1.62V or less, 1.6V or less, 1.57V or less, 1.55V or less, 1.52V or less, 1.5V or less, 1.47V or less, 1.45V or less, 1.42V or less, 1.4V or less, 1.37V or less, 1.35V or less, or A peak may exist at 1.3V or lower. The above ranges may be combined with each other.

[0575] When the above positive active material includes at least one selected from the group consisting of lithium cobalt oxide (LiCoO2), lithium nickel-cobalt-manganese oxide, and lithium-rich manganese oxide, a peak may exist at 1.5V to 2.0V in the V - dQ / dV graph obtained by differentiating the graph of voltage V and battery capacity Q measured by charging the lithium secondary battery. For example, when the positive electrode active material includes at least one selected from the group consisting of lithium cobalt oxide (LiCoO2), lithium nickel-cobalt-manganese oxide, and lithium-rich manganese oxide, a V - dQ / dV graph obtained by differentiating the graph of voltage V and battery capacity Q measured by charging the lithium secondary battery may have peaks at 1.5V or higher, 1.52V or higher, 1.55V or higher, 1.57V or higher, 1.6V or higher, 1.62V or higher, 1.65V or higher, 1.67V or higher, 1.7V or higher, 1.72V or higher, 1.75V or higher, 1.77V or higher, 1.8V or higher, 1.82V or higher, 1.85V or higher, 1.87V or higher, or 1.9V or higher. For example, when the above-mentioned positive active material includes at least one selected from the group consisting of lithium cobalt oxide (LiCoO2), lithium nickel-cobalt-manganese oxide, and lithium-rich manganese oxide, a V - dQ / dV graph obtained by differentiating the graph of voltage V and battery capacity Q measured by charging the lithium secondary battery may have peaks at 2.0V or less, 1.97V or less, 1.95V or less, 1.92V or less, 1.9V or less, 1.87V or less, 1.85V or less, 1.82V or less, 1.8V or less, 1.77V or less, 1.75V or less, 1.72V or less, 1.7V or less, 1.67V or less, 1.65V or less, 1.62V or less, 1.6V or less, 1.57V or less, 1.55V or less, or 1.52V or less. Each of the above ranges can be combined with one another.

[0576] When the above positive active material includes lithium iron phosphate, a peak may exist at 1.0V to 1.5V in the V - dQ / dV graph obtained by differentiating the graph of voltage V and battery capacity Q measured by charging the lithium secondary battery. For example, when the above positive active material includes lithium iron phosphate, in the V - dQ / dV graph obtained by differentiating the graph of voltage V and battery capacity Q measured by charging the lithium secondary battery, peaks may exist at 1.0V or higher, 1.02V or higher, 1.05V or higher, 1.07V or higher, 1.1V or higher, 1.12V or higher, 1.15V or higher, 1.17V or higher, 1.2V or higher, 1.22V or higher, 1.25V or higher, 1.27V or higher, 1.3V or higher, 1.32V or higher, 1.35V or higher, 1.37V or higher, 1.4V or higher, 1.42V or higher, 1.45V or higher, or 1.47V or higher. For example, when the positive electrode active material includes lithium iron phosphate, in the V - dQ / dV graph obtained by differentiating the graph of voltage V and battery capacity Q measured by charging the lithium secondary battery, peaks may exist at 1.5V or less, 1.47V or less, 1.45V or less, 1.42V or less, 1.4V or less, 1.37V or less, 1.35V or less, or 1.3V or less. Each of the above ranges may be combined with one another.

[0577]

[0578] Meanwhile, the external shape of the lithium secondary battery of the present invention is not particularly limited and can be cylindrical, prismatic, pouch-type, or coin-type.

[0579] In addition, the lithium secondary battery of the present invention can be usefully applied to portable devices such as mobile phones, laptop computers, and digital cameras, as well as in the field of electric vehicles such as hybrid electric vehicles (HEVs) and energy storage systems (ESS).

[0580]

[0581] Hereinafter, the present invention will be described in detail with reference to examples in order to specifically explain the invention. However, the embodiments according to the present invention may be modified in various different forms, and the scope of the present invention should not be interpreted as being limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the invention to those with average knowledge in the art.

[0582]

[0583] Examples and Comparative Examples

[0584] Example 1

[0585] (1) Preparation of a compound represented by Chemical Formula 2

[0586] Ethylene sulfate and LiNO3 were dissolved in ethyl acetate (EA) solvent at a ratio of 10 wt% with an equivalent ratio of 1.2:1, and then mixed at room temperature (15-25°C) to proceed with a compound formation reaction represented by Chemical Formula 1-a-1. Through the compound formation reaction, a compound represented by Chemical Formula 2 that was not dissolved in the ethyl acetate (EA) solvent was precipitated in powder form. The solution after the reaction was filtered to obtain powder. Subsequently, the ethyl acetate solvent remaining in the powder was evaporated, thereby obtaining the compound represented by Chemical Formula 2-a-1.

[0587]

[0588] The presence of the compound represented by the above chemical formula 2-a-1 is determined by HR-LC / MS (High Resolution Liquid Chromatography-Mass Spectrometry) and 1 It was confirmed using the H-NMR (H-Nuclear Magnetic Resonance Spectroscopy) method.

[0589] First, the compound (powder) represented by the above chemical formula 2-a-1 was added to an organic solvent mixed with ethylene carbonate, ethylmethyl carbonate, and dimethyl carbonate in a volume ratio of 30:50:20, and this was diluted in acetone D6 solvent to prepare a sample solution. Using the above sample solution, HR-LC / MS and 1 H-NMR was measured.

[0590] The HR-LC / MS instrument used was the ThermoFisher Orbitrap IQ-X Tribrid. Under the measurement conditions, CapcellPak C18 was used as the column, acetonitrile and trifluoroacetate (volume ratio 100:0.02) as eluent A, and distilled water and trifluoroacetate (volume ratio 100:0.02) as eluent B. The flow rate was set to 1 mL / min, the UV detector to 220 nm, and the ionization mode to the electron spray ionization (ESI) anionization mode. 1 The H-NMR instrument used was Bruker's Advance Neo instrument.

[0591] The presence of the compound represented by chemical formula 2-a-1 was confirmed through Figures 2 to 5. Specifically, the Extracted Ion Chromatogram (XIC) for m / z 185.97140 according to Figure 2 showed a single peak at 1.35 min, confirming that the compound represented by chemical formula 2-a-1 is present in the sample and separated on the LC.

[0592] In the MS spectrum according to Fig. 3, 185.97140 was observed, corresponding to the anion of the compound represented by chemical formula 2-a-1, which corresponds to the molecular formula C2H4NO7S of the compound represented by chemical formula 2-a-1. - It matched.

[0593] Through additional MS / MS analysis (Tandem MS, dual mass spectrometry) according to Fig. 4, fragment ions such as m / z 61.98818 (O3N) and 79.95725 (O3S) were detected, which are consistent with the expected structural decomposition pattern. These results support the presence and structural identity of the compound represented by Chemical Formula 2-a-1.

[0594] The characteristic chemical shifts of 4.76 (t,2) and 4.18 (t,2) observed in the ¹H-NMR spectrum according to Fig. 5 support the presence of a compound represented by the formula 2-a-1.

[0595]

[0596] (2) Preparation of non-aqueous electrolytes

[0597] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.0 M in an organic solvent mixed with ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then adding the compounds represented by the chemical formula 1-a-1, vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propanesulfone (PS) as additives. The compounds represented by the chemical formula 1-a-1, vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propanesulfone (PS) were included in the non-aqueous electrolyte at concentrations of 0.80 wt%, 3.00 wt%, 1.00 wt%, and 0.10 wt%, respectively.

[0598]

[0599] (3) Manufacturing of lithium secondary batteries

[0600] (Anode manufacturing)

[0601] A positive active material slurry (solid content 100 wt%) was prepared by mixing a positive active material (LiFePO4), a conductive material (carbon nanotube, CNT), and a binder (polytetrafluoroethylene, PTFE) in a weight ratio of 96.0:0.5:3.5. The positive active material slurry was applied to a positive current collector (Al thin film) with a thickness of 13 μm, and a positive electrode was manufactured by performing a roll press.

[0602] (Cathode manufacturing)

[0603] A cathode active material slurry (solid content: 53 wt%) was prepared by adding a cathode active material (a mixture of artificial graphite and natural graphite mixed in a weight ratio of 80:20), styrene-butadiene rubber and carboxymethylcellulose as binders, and carbon black as a conductive material to distilled water as a solvent in a weight ratio of 96.7:2.8:0.5. The cathode active material slurry was coated onto a cathode current collector (Cu thin film) with a thickness of 6 μm, dried, and rolled to produce a cathode.

[0604] (Manufacturing of lithium secondary batteries)

[0605] An electrode assembly was manufactured by interposing a porous separator polypropylene between the anode and cathode manufactured above, then housing it in a battery case, and a lithium secondary battery was manufactured by injecting the non-aqueous electrolyte manufactured above.

[0606] After installing the above lithium secondary battery in an electrochemical charge / discharger, it was charged to SOC 60 at a rate limit of 0.1C and aged to form a coating layer on the above negative electrode active material layer.

[0607]

[0608] Example 2

[0609] (1) Preparation of non-aqueous electrolytes

[0610] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.0 M in an organic solvent mixed with ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then adding as additives the compound represented by Chemical Formula 2-a-1 (prepared through the method according to Example 1), vinylene carbonate (VC), fluoroethylene carbonate (FEC), ethylene sulfate (ESa), and 1,3-propanesulfone (PS). The compound represented by Chemical Formula 2-a-1, vinylene carbonate (VC), fluoroethylene carbonate (FEC), ethylene sulfate (ESa), and 1,3-propanesulfone (PS) were included in the non-aqueous electrolyte at concentrations of 0.30 wt%, 3.00 wt%, 1.00 wt%, 0.80 wt%, and 0.20 wt%, respectively.

[0611]

[0612] (2) Manufacturing of lithium secondary batteries

[0613] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-mentioned non-aqueous electrolyte was used.

[0614]

[0615] Example 3

[0616] (1) Preparation of non-aqueous electrolytes

[0617] LiPF6 was dissolved to a concentration of 1.0 M in an organic solvent mixed with ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then a non-aqueous electrolyte was prepared by adding the compound represented by Chemical Formula 2-a-1 (prepared through the method according to Example 1), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) as additives. The compound represented by Chemical Formula 2-a-1, vinylene carbonate (VC), and fluoroethylene carbonate (FEC) were included in the non-aqueous electrolyte at concentrations of 1.50 wt%, 3.00 wt%, and 1.00 wt%, respectively.

[0618]

[0619] (2) Manufacturing of lithium secondary batteries

[0620] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-mentioned non-aqueous electrolyte was used.

[0621]

[0622] Comparative Example 1

[0623] (1) Preparation of non-aqueous electrolytes

[0624] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.0 M in an organic solvent mixed with ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then adding vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propane sulfone (PS). The non-aqueous electrolyte contained vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propane sulfone (PS) in amounts of 3.00 wt%, 1.00 wt%, and 0.2 wt%, respectively.

[0625]

[0626] (2) Manufacturing of lithium secondary batteries

[0627] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-mentioned non-aqueous electrolyte was used.

[0628]

[0629] Comparative Example 2

[0630] (1) Preparation of non-aqueous electrolytes

[0631] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.0 M in an organic solvent mixed with ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then adding LiNO3, vinylene carbonate (VC), and fluoroethylene carbonate (FEC). The non-aqueous electrolyte contained LiNO3, vinylene carbonate (VC), and fluoroethylene carbonate (FEC) in amounts of 0.25 wt%, 3.00 wt%, and 1.00 wt%, respectively.

[0632]

[0633] (2) Manufacturing of lithium secondary batteries

[0634] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-mentioned non-aqueous electrolyte was used.

[0635]

[0636] Comparative Example 3

[0637] (1) Preparation of non-aqueous electrolytes

[0638] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.0 M in an organic solvent mixed with ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then adding ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC). The non-aqueous electrolyte contained ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) in amounts of 0.50 wt%, 3.00 wt%, and 1.00 wt%, respectively.

[0639]

[0640] (2) Manufacturing of lithium secondary batteries

[0641] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-mentioned non-aqueous electrolyte was used.

[0642]

[0643] Comparative Example 4

[0644] (1) Preparation of non-aqueous electrolytes

[0645] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.0 M in an organic solvent mixed with ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then adding as additives the compound represented by Chemical Formula 2-a-1 (prepared through the method according to Example 1), ethylene sulfate (ESa), vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propanesulfone (PS). The compound represented by Chemical Formula 2-a-1, ethylene sulfate (ESa), vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propanesulfone (PS) were included in amounts of 0.20 wt%, 0.40 wt%, 3.00 wt%, 1.00 wt%, and 0.20 wt%, respectively.

[0646]

[0647] (2) Manufacturing of lithium secondary batteries

[0648] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-mentioned non-aqueous electrolyte was used.

[0649]

[0650] Comparative Example 5

[0651] (1) Preparation of non-aqueous electrolytes

[0652] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.0 M in an organic solvent mixed with ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then adding the compound represented by Chemical Formula 2-a-1 (prepared through the method according to Example 1), ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) as additives. The compound represented by Chemical Formula 2-a-1, ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) were included in amounts of 1.70 wt%, 0.70 wt%, 3.00 wt%, and 1.00 wt%, respectively.

[0653]

[0654] Comparative Example 6

[0655] (1) Preparation of non-aqueous electrolytes

[0656] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.0 M in an organic solvent mixed with ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then adding the compound represented by Chemical Formula 2-a-1 (prepared through the method according to Example 1), ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) as additives. The compound represented by Chemical Formula 2-a-1, ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) were included in amounts of 1.40 wt%, 0.30 wt%, 3.00 wt%, and 1.00 wt%, respectively.

[0657]

[0658] (2) Manufacturing of lithium secondary batteries

[0659] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-mentioned non-aqueous electrolyte was used.

[0660]

[0661] Comparative Example 7

[0662] (1) Preparation of non-aqueous electrolytes

[0663] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.0 M in an organic solvent mixed with ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then adding as additives the compound represented by Chemical Formula 2-a-1 (prepared through the method according to Example 1), ethylene sulfate (ESa), vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propanesulfone (PS). The compound represented by Chemical Formula 2-a-1, ethylene sulfate (ESa), vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propanesulfone (PS) were included in amounts of 1.40 wt%, 0.10 wt%, 3.00 wt%, 1.00 wt%, and 0.20 wt%, respectively.

[0664]

[0665] (2) Manufacturing of lithium secondary batteries

[0666] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-mentioned non-aqueous electrolyte was used.

[0667]

[0668] Comparative Example 8

[0669] (1) Preparation of non-aqueous electrolytes

[0670] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.0 M in an organic solvent mixed with ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then adding as additives a compound represented by Chemical Formula 2-a-1 (prepared through the method according to Example 1), vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propanesulfone (PS). The compound represented by Chemical Formula 2-a-1, vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propanesulfone (PS) were included in amounts of 0.30 wt%, 3.00 wt%, 1.00 wt%, and 1.50 wt%, respectively.

[0671]

[0672] (2) Manufacturing of lithium secondary batteries

[0673] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-mentioned non-aqueous electrolyte was used.

[0674]

[0675] Comparative Example 9

[0676] (1) Preparation of non-aqueous electrolytes

[0677] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.0 M in an organic solvent mixed with ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then adding the compound represented by Chemical Formula 2-a-1 (prepared through the method according to Example 1), ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) as additives. The compound represented by Chemical Formula 2-a-1, ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) were included in amounts of 0.30 wt%, 1.50 wt%, 3.00 wt%, and 1.00 wt%, respectively.

[0678]

[0679] (2) Manufacturing of lithium secondary batteries

[0680] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-mentioned non-aqueous electrolyte was used.

[0681]

[0682] Comparative Example 10

[0683] (1) Preparation of non-aqueous electrolytes

[0684] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.0 M in an organic solvent mixed with ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then adding the compound represented by Chemical Formula 2-a-1 (prepared through the method according to Example 1), vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propanesulfone (PS) as additives. The compound represented by Chemical Formula 2-a-1, vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propanesulfone (PS) were included in amounts of 0.70 wt%, 3.00 wt%, 1.00 wt%, and 1.00 wt%, respectively.

[0685]

[0686] (2) Manufacturing of lithium secondary batteries

[0687] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-mentioned non-aqueous electrolyte was used.

[0688]

[0689] Comparative Example 11

[0690] (1) Preparation of non-aqueous electrolytes

[0691] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.0 M in an organic solvent mixed with ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then adding the compound represented by Chemical Formula 2-a-1 (prepared by the method according to Example 1), ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) as additives. The compound represented by Chemical Formula 2-a-1, ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) were included in amounts of 0.70 wt%, 1.00 wt%, 3.00 wt%, and 1.00 wt%, respectively.

[0692]

[0693] (2) Manufacturing of lithium secondary batteries

[0694] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-mentioned non-aqueous electrolyte was used.

[0695]

[0696] Additives (weight %, based on weight of non-aqueous electrolyte) Total weight of the compound represented by Chemical Formula 2-a-1, ESa, and PS Chemical Formula 2-a-1 ESaLiNO3VCFECPS Example 1 0.80 -- 3.00 1.00 0.10 0.90 Example 2 0.30 0.80 -- 3.00 1.00 0.20 1.30 Example 3 1.50 -- 3.00 1.00 - 1.50 Comparative Example 1 -- 3.00 1.00 0.20 0.20 Comparative Example 2 -- 0.25 3.00 1.00 - 0 Comparative Example 3 -- 0.50 -- 3.00 1.00 - 0.50 Comparative Example 4 0.20 0.40 -- 3.00 1.00 0.20 0.80 Comparative Example 51.700.70 -3.001.00 -2.40 Comparative Example 61.400.30 -3.001.00 -1.70 Comparative Example 71.400.10 -3.001.000.20 1.70 Comparative Example 80.30 -3.001.001.50 1.80 Comparative Example 90.30 1.50 -3.001.00 -1.80 Comparative Example 100.70 -3.001.001.001.70 Comparative Example 110.70 1.00 -3.001.00 -1.70

[0697]

[0698] Experimental Example 1: Coating Layer Analysis

[0699] (1) Analysis of the thickness of the coating layer

[0700] In the lithium secondary batteries of the examples and comparative examples in a state of 0% SOC, the negative electrode was decomposed in a glove box in an Ar atmosphere, and the decomposed negative electrode was washed and dried with a washing solvent (e.g., DMC solvent).

[0701] After fixing the above-mentioned washed and dried cathode to a sample holder for XPS, the coating layer was etched stepwise using an argon single-atom sputtering gun to the surface of the cathode active material layer for 0, 10, 30, 50, 100, 200, 300, 500, 1000, 1500, 2000, 3000, and 4000 seconds. At this time, using an XPS device, the etching thickness until the elemental ratio of the major element (carbon) of the cathode active material in the above-mentioned cathode active material layer reaches 70 elemental% during XPS analysis was defined as the thickness of the coating layer. Since the above coating layer contains a complex composition of multiple elements, making it difficult to accurately determine the etching thickness, the etching rate of the coating layer was assumed to be the same as the etching rate of tantalum pentoxide (Ta2O5) (0.09 nm / sec), and the thickness of the coating layer was calculated by multiplying the etching time by the etching rate.

[0702] The thickness of the assumed coating layer above is shown in Table 2 below.

[0703]

[0704] <XPS의 측정 조건>

[0705] The measurement conditions for XPS analysis are as follows.

[0706] - XPS equipment name: K-Alpha, Thermo Fisher Scientific

[0707] - X-ray source: Monochromated Al Kα (1486.6 eV)

[0708] - X-ray spot size: 400 µm

[0709] - Etching conditions (sputtering gun): monatomic Ar (energy: 1000 eV, current: low, raster width: 2 mm), 0.09 nm / s etching rate (based on Ta2O5)

[0710] - Charge compensation (flood gun): Off

[0711] - Survey scan: pass energy 200 eV, energy step 1 eV

[0712] - Narrow scan: pass energy 50 eV, energy step 0.1 eV

[0713] - Sensitivity factor (SF): Al THERMO1, Energy correction factor (ECF): TPP-2M

[0714] - Background subtraction: Smart

[0715] - Binding energy correction: Shifts the binding energy of the CC and CH (sp3-C) peaks in the C 1s spectrum to 285 eV.

[0716]

[0717] Thickness of coating layer (nm) Example 1 135 Example 2 135 Example 3 135 Comparative Example 190 Comparative Example 290 Comparative Example 3 135 Comparative Example 4 135 Comparative Example 5 180 Comparative Example 6 180 Comparative Example 7 135 Comparative Example 8 135 Comparative Example 9 135 Comparative Example 10 180 Comparative Example 11 135

[0718]

[0719] By measuring the thickness of the coating layer, the presence of the coating layer formed on the cathode active material layer can be confirmed.

[0720]

[0721] (2) XPS analysis of the coating layer

[0722] In the lithium secondary batteries of the examples and comparative examples with an SOC of 0%, the negative electrode was decomposed in a glove box with an Ar atmosphere, and the decomposed negative electrode was washed and dried with a washing solvent (e.g., DMC solvent). After fixing the washed and dried negative electrode to a sample holder for XPS, the composition of the coating layer was analyzed using an XPS device. At this time, the XPS analysis of the coating layer was performed after etching with an argon single-atom sputtering gun for 10 seconds to remove surface contaminants.

[0723] The analysis conditions for XPS are as described in "(1) Analysis of coating layer thickness" above. The results are shown in Table 3 below.

[0724]

[0725] The results are shown in Table 3 below.

[0726]

[0727] Elemental Analysis (Element%) S / N Element Ratio S / C Element Ratio N / C Element Ratio CNSLiOFPNa Example 1 44.20 1.20 1.36 16.27 20.71 15.76 0.37 0.13 1.13 30.03 00.027 Example 2 44.76 1.19 1.38 17.45 22.09 12.59 0.44 0.10 1.16 00.03 10.027 Example 3 43.12 1.52 2.31 18.36 25.43 8.79 0.30 0.17 1.52 00.05 40.035 Comparative Example 150.360.700.1713.6817.4417.210.350.090.2430.0020.014 Comparative Example 248.501.51015.9218.9414.600.510.02000.031 Comparative Example 346.940.680.7816.8522.0612.190.460.041.1470.0170.014 Comparative Example 445.640.971.3816.0520.4815.030.350.101.4230.0300.021 Comparative Example 534.581.444.2823.1231.934.250.280.122.9720.1240.042 Comparative Example 639.411.302.7819.5826.659.880.280.122.1380.0710.033 Comparative Example 741.011.552.7722.0928.533.620.290.141.7870.0680.038 Comparative Example 843.251.452.6020.1528.134.020.310.091.7930.0600.034 Comparative Example 942.221.383.0020.1428.384.360.420.102.1740.0710.033 Comparative Example 1038.461.642.6722.1627.417.070.460.131.6280.0690.043 Comparative Example 1141.531.062.9317.1524.0612.850.340.082.7640.0700.026

[0728]

[0729] Experimental Example 2: NMR Analysis of the Coating Layer

[0730] In the lithium secondary batteries of the examples, the negative electrode was decomposed in a glove box under an Ar atmosphere, and the decomposed negative electrode was washed and dried with a washing solvent (e.g., DMC solvent). After immersing the washed and dried negative electrode in a D2O solvent for at least 20 hours, the solution was filtered through a 0.45 μm PVDF membrane filter. 1 It was applied to H-NMR analysis. The entire process of decomposition, extraction, and filtering was carried out inside a glove box under an Ar atmosphere. The measurement conditions for NMR analysis are as follows.

[0731] <NMR 측정 조건>

[0732] NMR Instrument Name: Bruker Advance Neo

[0733] Parameters: resonance frequency = 500 MHz, ns = 16, d1 = 5sec, spectra width = -4 - 16 ppm

[0734]

[0735] Regarding the coating layers of Examples 1 to 3 1 H-NMR spectra are shown in Figures 6 to 8, respectively.

[0736] The presence of a compound represented by Chemical Formula 1-1 within the coating layer can be confirmed through FIGS. 6 to 8. Specifically, 1 The presence of the compound can be confirmed through the 4.1 (t, 2H) and 3.8 (t, 2H) ppm peaks in the H-NMR spectrum.

[0737]

[0738] Experimental Example 3: High-temperature cycle performance evaluation

[0739] High-temperature cycle performance evaluation was performed on the lithium secondary batteries of the examples and comparative examples manufactured above.

[0740] Specifically, the lithium secondary batteries of the examples and comparative examples were charged to 3.8V at 0.33C at 45℃ using a constant current / constant voltage (CC / CV) method (0.05C cut-off), and discharged to 2.5V at 0.33C using a constant current (CC) method, with the discharge capacity after one cycle being measured.

[0741] Then, after performing 300 charge-discharge cycles under the charge-discharge conditions described above, the capacity retention rate (%) was measured. The capacity retention rate (%) was calculated according to the following formula. The results are shown in Figure 9 and Table 4.

[0742] Capacity Retention Rate (%) = (Discharge Capacity after 300 cycles / Discharge Capacity after 1 cycle) × 100

[0743]

[0744] Dose Retention Rate (%, 300th Cycle) Example 1: 1.38 Example 2: 0.66 Example 3: 1.02 Comparative Example 1: 1.39 Comparative Example 2: 4.58 Comparative Example 3: 6.97 Comparative Example 4: 87.06 Comparative Example 5: 87.79 Comparative Example 6: 88.06 Comparative Example 7: 87.77 Comparative Example 8: 87.69 Comparative Example 9: 87.30 Comparative Example 10: 87.49 Comparative Example 11: 88.53

[0745]

[0746] Referring to Table 4 and Figure 9 above, it can be seen that the lithium secondary batteries of the embodiments in which the elemental ratio of sulfur (S) to nitrogen (N), the elemental ratio of sulfur (S) to carbon (C), and the elemental ratio of nitrogen (N) to carbon (C) of the coating layer satisfy the scope of the present invention exhibit significantly superior cycle performance compared to the comparative examples.

[0747]

[0748] [Explanation of the symbol]

[0749] 10: Cathode

[0750] 100: Whole house

[0751] 110: Cathode active material layer

[0752] 120: Coating layer

Claims

1. Cathode; An anode facing the above cathode; A separator interposed between the above cathode and the above anode; and Includes non-aqueous electrolytes, The above cathode comprises a current collector, a cathode active material layer located on at least one surface of the current collector, and a coating layer located on at least a portion of the surface of the cathode active material layer; A lithium secondary battery in which, upon XPS analysis of the coating layer, the atomic ratio of sulfur (S) to nitrogen (N) is 0.500 to 1.550, the atomic ratio of sulfur (S) to carbon (C) is 0.018 to 0.059, and the atomic ratio of nitrogen (N) to carbon (C) is 0.022 to 0.

037.

2. In Claim 1, The above negative electrode active material layer includes a negative electrode active material, and The above negative electrode active material comprises at least one selected from carbon-based active materials and silicon-based active materials, forming a lithium secondary battery.

3. In Claim 1, The above positive electrode comprises a current collector and a positive active material layer located on at least one surface of the current collector, and The above positive active material layer comprises a lithium metal composite oxide, and The lithium metal composite oxide comprises at least one selected from lithium cobalt oxide (LiCoO2), lithium nickel-cobalt-manganese oxide, lithium-rich manganese oxide, and lithium iron phosphate, forming a lithium secondary battery.

4. In Claim 1, The above coating layer comprises a lithium secondary battery containing a compound represented by the following chemical formula 1: [Chemical Formula 1] In the above chemical formula 1, L1 is an alkylene group having 1 to 10 carbon atoms, and M is a metal cation or an organic cation, and a is the valence of M when M is a metal cation, and 1 when M is an organic cation, and a × n = 2 × m.

5. In Claim 4, A lithium secondary battery in which the compound represented by the above chemical formula 1 is the compound represented by the following chemical formula 1-A: [Chemical Formula 1-A] In the above chemical formula 1-A, M, a, n, and m are as defined in the above chemical formula 1.

6. In Claim 4, The above M is a metal cation, and The above M is a lithium secondary battery selected from the group consisting of Li, K, Ca, Mg and Cs.

7. In Claim 4, The above M is an organic cation, and The above M is an electrode selected from the group consisting of compounds represented by the following chemical formulas M-1 to M-6: [Chemical Formula M-1] In the above chemical formula M-1, X M1 is -N(R M15 )- or -S- and, R M11 , R M12 , R M13 , R M14 and R M15 The groups are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. [Chemical Formula M-2] In the above chemical formula M-2, X M2 is -N(R M25 )- or -S- and, R M21 , R M22 , R M23 , R M24 and R M25 The groups are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. [Chemical Formula M-3] In the above chemical formula M-3, R M31 , R M32 , R M33 , R M34 , R M35 and R M36 The groups are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. [Chemical Formula M-4] In the above chemical formula M-4, R M41 , R M42 , R M43 and R M44 is independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and R M41 , R M42 , R M43 and R M44 At least two of them are alkyl groups having 1 to 5 carbon atoms, and they can be bonded together to form an aliphatic hydrocarbon ring. [Chemical Formula M-5] In the above chemical formula M-5, R M51 , R M52 , R M53 and R M54 is independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and R M51 , R M52 , R M53 and R M54 At least two of these can be combined to form an aliphatic hydrocarbon ring. [Chemical Formula M-6] In the above chemical formula M-6, R M61 , R M62 and R M63 is independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoethyl group having 1 to 12 carbon atoms, an alkoxyalkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and R M61 , R M62 and R M63 At least two of these can be combined to form an aliphatic hydrocarbon ring.

8. In Claim 4, A lithium secondary battery in which the compound represented by the above chemical formula 1 is the compound represented by the following chemical formula 1-1: [Chemical Formula 1-1] .

9. In Claim 1, A lithium secondary battery in which peaks are found at 401 eV to 395 eV and 172 eV to 168 eV in the intensity-binding energy graph according to XPS analysis of the coating layer.

10. In Claim 1, A lithium secondary battery in which, when XPS analyzed, the atomic ratio of sulfur (S) to nitrogen (N) is 0.794 to 1.

520.

11. In Claim 1, A lithium secondary battery in which, when XPS analyzed, the elemental ratio of sulfur (S) to carbon (C) is 0.018 to 0.

055.

12. In Claim 1, A lithium secondary battery in which, when XPS analyzed, the elemental ratio of nitrogen (N) to carbon (C) is 0.023 to 0.037.

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