Positive electrode and lithium secondary battery comprising same

Abstract

The present invention relates to a positive electrode which comprises: a positive electrode current collector; and a positive electrode active material layer disposed on the positive electrode current collector, wherein the positive electrode active material layer includes a positive electrode active material and a compound represented by chemical formula 1. Specific details of the compound represented by chemical formula 1 are as described in the present specification.

Description

Anode and lithium secondary battery including the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0189220 filed on December 17, 2024, and all contents disclosed in said Korean Patent Application are incorporated into this specification.

[0003] Technology field

[0004] The present invention relates to a positive electrode and a lithium secondary battery including the same, and more specifically, to a positive electrode with excellent electrochemical performance and a lithium secondary battery including the same.

[0005]

[0006] Lithium secondary batteries are used in a wide range of fields, including small products such as digital cameras, P-DVDs, MP3s, mobile phones, PDAs, portable game devices, power tools, and E-bikes, as well as large products requiring high output such as electric vehicles and hybrid vehicles, and power storage devices and backup power storage devices that store surplus power or renewable energy.

[0007] In particular, as lithium-ion batteries are used in large-scale products requiring high power output, such as electric vehicles, the need for lithium-ion batteries with high energy density is increasing. Furthermore, achieving high energy density in lithium-ion batteries requires a high operating voltage, but under high operating voltages, continuous oxidative decomposition reactions of the electrolyte may occur.

[0008] The oxidative decomposition reaction of the above electrolyte causes problems such as depletion of the non-aqueous electrolyte, gas generation within the lithium secondary battery, breakdown of the coating, and leaching of the transition metal active material of the cathode, which impair the lifespan and high-temperature performance of the lithium secondary battery. Furthermore, these problems can be accelerated by the heat generated during the operation of the lithium secondary battery.

[0009] Therefore, to overcome the aforementioned problems, there is a need for a technology that can improve high-temperature durability and long-term lifespan performance by forming a highly durable film on the surface of an electrode that generates a high amount of oxidizing gas under high voltage.

[0010]

[0011] The present invention aims to solve the above-mentioned problems by forming a highly durable film on the surface of the anode to improve the stability of the interface between the anode and the electrolyte, thereby providing an anode capable of suppressing oxidative decomposition of the electrolyte and gas generation.

[0012] In addition, the present invention can provide a lithium secondary battery with excellent electrochemical performance and high-temperature performance by including the above-mentioned anode.

[0013]

[0014] [1] The present invention provides a positive electrode comprising a positive current collector and a positive active material layer located on the positive current collector, wherein the positive active material layer comprises a positive active material and a compound represented by the following chemical formula 1:

[0015] [Chemical Formula 1]

[0016]

[0017] In the above chemical formula 1, R1 is an alkyl group having 1 to 10 carbon atoms or an alkyl group having 1 to 10 carbon atoms substituted with one or more fluorines, and R 21 , R 22 , R 23 , and R 24is independently hydrogen or an alkyl group having 1 to 5 carbon atoms, and L is a direct bond, an ether group (*-O-*) or an ester group (*-C(=O)O-*).

[0018] [2] The present invention may provide an anode comprising, in the above [1], a compound represented by the chemical formula 1 and a compound represented by the chemical formula 1-A.

[0019] [Chemical Formula 1-A]

[0020]

[0021] In the above chemical formula 1-A, R1 and L are as defined in the above formula 1.

[0022] [3] The present invention may provide an anode in which, in [1] or [2], R1 of the formula 1 is an alkyl group having 1 to 5 carbon atoms or an alkyl group having 1 to 5 carbon atoms substituted with one or more fluorines.

[0023] [4] The present invention may provide an anode in which, in at least one of [1] to [3], R1 of Formula 1 is an alkyl group having 1 to 5 carbon atoms or a perfluoroalkyl group having 1 to 5 carbon atoms.

[0024] [5] The present invention may provide an anode comprising, in at least one of [1] to [4], a compound represented by Formula 1, selected from the group consisting of compounds represented by Formulas 1-1 to 1-8:

[0025] [Chemical Formula 1-1]

[0026]

[0027] [Chemical Formula 1-2]

[0028]

[0029] [Chemical Formula 1-3]

[0030]

[0031] [Chemical Formula 1-4]

[0032]

[0033] [Chemical Formula 1-5]

[0034]

[0035] [Chemical Formula 1-6]

[0036]

[0037] [Chemical Formula 1-7]

[0038]

[0039] [Chemical Formula 1-8]

[0040] .

[0041] [6] The present invention may provide a positive electrode in which, in at least one of [1] to [5], the compound represented by Formula 1 is included in the positive electrode active material layer in an amount of 0.001% to 10% by weight.

[0042] [7] The present invention provides a lithium secondary battery comprising a positive electrode according to at least one of [1] to [6]; a negative electrode; a separator; and a non-aqueous electrolyte.

[0043] [8] The present invention can provide a lithium secondary battery in which the non-aqueous electrolyte of [7] comprises a lithium salt, an organic solvent, and an additive.

[0044] [9] The present invention can provide a lithium secondary battery comprising one or more additives selected from the group consisting of cyclic carbonate compounds, sulfate compounds, sulfone compounds, nitrile compounds, benzene compounds, lithium salt compounds, amine compounds and silane compounds, in accordance with [8].

[0045]

[0010] The present invention can provide a lithium secondary battery in which, in [8] above, the organic solvent comprises one or more selected from the group consisting of a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, a linear ester-based organic solvent, and a cyclic ester-based organic solvent.

[0046]

[0047] The anode of the present invention is characterized by including a compound capable of forming a film with improved durability on the anode active material layer, thereby improving the stability of the interface between the anode and the electrolyte to prevent oxidative decomposition of the non-aqueous electrolyte, which suppresses increased resistance and gas generation.

[0048] According to the present invention, a film with excellent durability can be formed on the cathode due to the cathode active material containing the compound, and the mobility of lithium ions can be improved due to the non-covalent electron pairs included in the compound. As a result, a lithium secondary battery with excellent electrochemical performance and high-temperature performance can be realized.

[0049]

[0050] Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but 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.

[0051] In this specification, terms such as “comprising,” “comprising,” 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.

[0052] In this specification, each of the phrases such as “A or B”, “at least one of A and B”, “at least one of A or B”, “A, B or C”, “at least one of A, B and C”, and “at least one of A, B, or C” may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof.

[0053] In this specification, “a” and “b” of “carbon number a to 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.

[0054] In this specification, “substitution” means that at least one hydrogen bonded to carbon is substituted with another element, such as fluorine, unless otherwise defined.

[0055] In this specification, “*” refers to a bonding site in a chemical formula unless otherwise defined.

[0056] In this specification, “volume%” is understood to mean a volume content based on the total volume of the composition, whereas “weight%” is understood to represent a weight content or mass content based on the total weight or mass of the composition.

[0057]

[0058] The present invention will be described in detail below.

[0059] The positive electrode and / or lithium secondary battery according to the present invention comprises at least one of the configurations disclosed below, and may comprise any combination of technically feasible configurations among the configurations below.

[0060]

[0061] anode

[0062] The present invention relates to a positive electrode comprising a positive electrode current collector and a positive electrode active material layer located on the positive electrode current collector.

[0063] The above positive current collector is not particularly limited as long as it is conductive without causing chemical changes in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used.

[0064] Meanwhile, the anode according to the present invention comprises an anode active material layer, and the anode active material layer comprises an anode active material and a phosphorus (P)-based compound represented by Chemical Formula 1.

[0065] Generally, when lithium secondary batteries are driven at high voltage to improve energy density, the occurrence of oxidative decomposition of the electrolyte at the cathode increases, leading to severe gas generation and causing problems such as the leaching of transition metals from the cathode active material.

[0066] To address these issues, attempts have been made to form electrode films using phosphorus (P)-based compounds as additives in non-aqueous electrolytes. However, when the aforementioned phosphorus-based compounds are included as additives in non-aqueous electrolytes, their high reactivity leads to reductive decomposition at the cathode. This reductive decomposition causes excessive participation in the cathode reaction, making it difficult for the reaction to occur at the anode, which in turn leads to a degradation of anode performance. Consequently, there was a problem in realizing the film intended by the present invention on the anode.

[0067] Accordingly, the anode according to the present invention can directly form a phosphorus-based film on the anode by applying the phosphorus-based compound to the anode active material layer, and can remove lithium byproducts through a chemical reaction with lithium byproducts. As a result, the amount of gas generated by the anode can be reduced and a robust film can be realized, thereby improving the electrochemical performance and high-temperature performance of the lithium secondary battery.

[0068]

[0069] (1) Phosphorus (P) compounds

[0070] The positive active material layer according to the present invention comprises a positive active material and a phosphorus-based compound represented by the following chemical formula 1:

[0071] [Chemical Formula 1]

[0072]

[0073] In the above chemical formula 1, R1 is an alkyl group having 1 to 10 carbon atoms or an alkyl group having 1 to 10 carbon atoms substituted with one or more fluorines, and R 21 , R 22 , R 23 , and R 24 is independently hydrogen or an alkyl group having 1 to 5 carbon atoms, and L is a direct bond, an ether group (*-O-*) or an ester group (*-C(=O)O-*).

[0074] The compound represented by Formula 1 according to the present invention can form a robust film by including R1. For example, when a phosphorus-based compound represented by Formula a below is applied to the positive electrode active material layer, side reactions with the electrolyte increase due to protons located in phosphorus, which may cause a problem of deterioration in the durability of the film formed on the positive electrode. In addition, when present in the electrolyte, the degradation of the secondary battery may be accelerated due to an increase in the acidity of the electrolyte caused by deprotonation:

[0075] [Chemical formula a]

[0076]

[0077] Accordingly, the present invention can improve the durability and high-temperature safety of the anode film by reducing side reactions with the electrolyte by applying a compound represented by Chemical Formula 1, which is substituted with R1, to the anode active material layer.

[0078] In addition, the compound represented by the above chemical formula 1 is an oxygen-rich compound, and since a large amount of non-covalent electron pairs exist within the structure of the compound, the mobility characteristics of lithium ions can be improved.

[0079] In the compound represented by Formula 1 according to the present invention, R1 may be an alkyl group having 1 to 5 carbon atoms or an alkyl group having 1 to 5 carbon atoms substituted with one or more fluorine (F). As described above, the alkyl group may be substituted with an alkyl group instead of a proton in phosphorus to reduce side reactions with the electrolyte. When the number of carbon atoms in the alkyl group satisfies 1 to 5, the structure of the monomer is small, allowing for the formation of a stable solvation structure in the solvent and improved dispersion characteristics, which can be evenly distributed on the surface of the anode. This contributes to the uniform formation of a film on the surface of the anode, thereby improving the electrochemical performance of the secondary battery.

[0080] In the compound represented by Formula 1 according to the present invention, R1 may be an alkyl group having 1 to 5 carbon atoms or a perfluoroalkyl group having 1 to 5 carbon atoms. For example, R1 may be *-CH3, *-CF3, *-CH2CH3, *-CF2CF3, *-CH2CH2CH3, *-CF2CF2CF3, *-CH2CH2CH2CH3, *-CF2CF2CF2CF3, *-CH2CH2CH2CH2CH3, or *-CF2CF2CF2CF2CF3. Specifically, R1 may be a perfluoroalkyl group having 1 to 5 carbon atoms, and due to the large amount of fluorine located in the perfluoroalkyl group, an inorganic film of LiF may be formed, thereby improving the mechanical durability of the film formed on the anode.

[0081] In the compound represented by Formula 1 according to the present invention, L may be an ether group (*-O-*) or an ester group (*-C(=O)O-*). When L satisfies the above range, the ether group and the ester group contain oxygen within the linker structure, making it easy to adsorb onto the anode surface, thereby enabling the stable and uniform formation of a film on the anode surface. Furthermore, the ether group and the ester group contain a large amount of non-covalent electron pairs, which can form a film with improved lithium ion mobility characteristics.

[0082] The compound represented by Formula 1 according to the present invention may include a compound represented by the following Formula 1-A:

[0083] [Chemical Formula 1-A]

[0084]

[0085] In the above Chemical Formula 1-A, R1 and L are as defined in the above Chemical Formula 1. The compound represented by the above Chemical Formula 1-A is the R of the compound represented by the above Chemical Formula 1. 21 , R 22 , R 23 , and R 24 It can be a compound that is hydrogen.

[0086] The compound represented by the above chemical formula 1 may include one or more selected from the group consisting of compounds represented by the following chemical formulas 1-1 to 1-8:

[0087] [Chemical Formula 1-1]

[0088]

[0089] [Chemical Formula 1-2]

[0090]

[0091] [Chemical Formula 1-3]

[0092]

[0093] [Chemical Formula 1-4]

[0094]

[0095] [Chemical Formula 1-5]

[0096]

[0097] [Chemical Formula 1-6]

[0098]

[0099] [Chemical Formula 1-7]

[0100]

[0101] [Chemical Formula 1-8]

[0102] .

[0103] The compounds represented by the above chemical formulas 1-1 to 1-8 may be preferred examples of chemical formula 1. When the compound of chemical formula 1 includes one or more selected from the group consisting of compounds represented by chemical formulas 1-1 to 1-8, there is an advantage that a film can be formed on the anode with excellent coverage and durability, while also having improved ion conductivity and reduced resistance.

[0104] The compound represented by Chemical Formula 1 above may be included in the positive active material layer in an amount of 0.001 wt% or more, 0.004 wt% or more, 0.04 wt% or more, 0.08 wt% or more, or 0.1 wt% or more. Additionally, the compound represented by Chemical Formula 1 may be included in the positive active material layer in an amount of 10 wt% or less, 9 wt% or less, 8.5 wt% or less, 5 wt% or less, 4.5 wt% or less, or 0.4 wt% or less.

[0105] More specifically, the compound represented by Chemical Formula 1 may be included in the non-aqueous electrolyte in an amount of 0.001 wt% to 10 wt%, specifically 0.004 wt% to 9 wt%, more specifically 0.004 wt% to 8.5 wt%, even more specifically 0.04 wt% to 8.5 wt%, even more specifically 0.04 wt% to 5 wt%, and even more specifically 0.04 wt% to 4.5 wt%. When the content of the compound represented by Chemical Formula 1 satisfies the above range, it is desirable in that it can realize an electrode film with excellent ion conductivity and durability as described above, thereby improving the lifespan performance of the lithium secondary battery while preventing side reactions caused by the excessive use of additives, which in turn prevents an increase in resistance.

[0106]

[0107] (2) Positive active material

[0108] The cathode active material according to the present invention is a compound capable of reversible intercalation and deintercalation of lithium, and specifically may include a lithium metal oxide comprising lithium and one or more metals such as cobalt, manganese, nickel, or aluminum. More specifically, the lithium metal oxide is a lithium-manganese-based oxide (e.g., LiMnO2, LiMn2O4, etc.), a lithium-cobalt-based oxide (e.g., LiCoO2, etc.), a lithium-nickel-based oxide (e.g., LiNiO2, etc.), or a lithium-nickel-manganese-based oxide (e.g., LiNi 1-Y Mn Y O2(here, 0 <Y<1), LiMn 2-Z Ni Z O4 (where 0 < Z < 2), etc.), lithium-nickel-cobalt oxides (e.g., LiNi 1-Y1 Co Y1 O2(here, 0 <Y1<1) 등), 리튬-망간-코발트계 산화물(예를 들면, LiCo 1-Y2 Mn Y2 O2(here, 0 <Y2<1), LiMn 2-Z1 CoZ1 O4 (where 0 < Z1 < 2), etc.), lithium-nickel-manganese-cobalt oxides (e.g., Li(Ni p Co q Mn r )O2(where, 0<p<1, 0<q<1, 0<r<1, p+q+r=1) or Li(Ni p1 Co q1 Mn r1 )O4 (where 0<p1<2, 0<q1<2, 0<r1<2, p1+q1+r1=2), etc.), or lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li(Ni p2 Co q2 Mn r2 M s2 Examples include )O2(wherein M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg and Mo, and p2, q2, r2 and s2 are each atomic fractions of independent elements, such that 0<p2<1, 0<q2<1, 0<r2<1, 0<s2<1, p2+q2+r2+s2=1), etc., and any one or more of these compounds may be included.

[0109] Specifically, the above positive active material may include a lithium transition metal oxide represented by the following [Chemical Formula 3].

[0110] [Chemical Formula 3]

[0111] Li x Ni a Co b M 1 c M 2 d O2

[0112] In the above chemical formula 3, the M 1 It is one or more selected from Mn and Al, and preferably, for durability, it may be Mn or a combination of Mn and Al.

[0113] The above M 2It may be one or more selected from the group consisting of Zr, Y, B, W, Mg, Ce, Hf, Ta, La, Ti, Sr, Ba, F, P, and S.

[0114] The above x represents the atomic fraction of lithium in the lithium transition metal oxide, and may be 0.90≤x≤1.1, preferably 0.95≤x≤1.08, and more preferably 1.0≤x≤1.08.

[0115] The above a represents the atomic fraction of nickel among metal elements excluding lithium in the lithium transition metal oxide, and may be 0.50≤a<1.0, 0.60≤a≤0.95, 0.65≤a≤0.95, or 0.80≤a≤0.95. When the nickel content satisfies the above range, high capacity characteristics can be achieved.

[0116] The above b represents the atomic fraction of cobalt among the metal elements excluding lithium in the lithium transition metal oxide, where 0 <b<0.5, 0<b<0.4, 또는 0.01≤b≤0.3일 수 있다.

[0117] The above c is M among the metal elements excluding lithium in the lithium transition metal oxide. 1 Representing the atomic fraction of, 0 <c<0.5, 0<c<0.4, 또는 0.01≤c≤0.3일 수 있다.

[0118] The above d is M among the metal elements excluding lithium in the lithium transition metal oxide. 2 It represents the atomic fraction of , which can be 0≤d≤0.1 or 0≤d≤0.05.

[0119] The above positive active material may be included in an amount of 60 to 99 weight%, preferably 70 to 99 weight%, and more preferably 80 to 98 weight% based on the total weight of the positive active material layer.

[0120]

[0121] Meanwhile, the positive active material layer according to the present invention may optionally further include a binder and / or a conductive material.

[0122] The above binder is a component that assists in the bonding of the positive active material and the positive conductive material, as well as the bonding to the current collector. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene (PE), polypropylene, ethylene-propylene-diene monomer (EPDM), sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, and various copolymers.

[0123] Typically, the binder may be included in an amount of 1 to 20 weight%, preferably 1 to 15 weight%, and more preferably 1 to 10 weight% based on the total weight of the positive active material layer.

[0124] The above conductive material is a component for further improving the conductivity of the positive electrode active material, and is not particularly limited as long as it is conductive without causing chemical changes in the battery. For example, carbon powder such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; graphite powder such as natural graphite, artificial graphite, or graphite with a highly developed crystal structure; conductive fibers such as carbon fibers or metal fibers; fluorinated carbon; conductive powder such as aluminum powder or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives may be used.

[0125] Typically, the conductive material may be included in an amount of 1 to 20 weight%, preferably 1 to 15 weight%, and more preferably 1 to 10 weight% based on the total weight of the positive active material layer.

[0126] The above positive active material layer may be manufactured by applying and drying a positive slurry composition prepared by dissolving or dispersing a positive active material, and optionally a binder and a conductive material, in a positive slurry solvent on a positive current collector, or by casting the above positive slurry composition onto a separate support and then laminating the film obtained by peeling off from the support onto a positive current collector.

[0127] The above anode slurry solvent may include organic solvents such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), and acetone, and may be used in an amount that results in a desirable viscosity when including the anode active material, anode binder, and anode conductive material. For example, the concentration of the solid component including the anode active material, and optionally the anode binder and anode conductive material, may be 50 to 95 weight%, preferably 70 to 95 weight%, and more preferably 70 to 90 weight%.

[0128]

[0129] lithium secondary battery

[0130] Next, a lithium secondary battery according to the present invention will be described.

[0131] The lithium secondary battery according to the present invention comprises the anode described above, a negative electrode facing the anode, a separator interposed between the anode and the negative electrode, and an electrolyte. At this time, since the anode is identical to the anode according to the present invention described above, a detailed description is omitted, and the remaining components excluding the anode will be described below.

[0132]

[0133] (1) Cathode

[0134] In a lithium secondary battery according to the present invention, the negative electrode comprises a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector.

[0135] The above-mentioned negative current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, heat-treated carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloy may be used.

[0136] The above-mentioned negative current collector can typically have a thickness of 3 μm to 500 μm, and preferably can have a thickness of 300 μm or less, 200 μm or less, 100 μm or less, or 80 μm or less. Fine irregularities may be formed on the surface of the current collector to strengthen the bonding force with the negative active material. For example, it can be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0137] The above-mentioned negative electrode active material may be a compound capable of reversible intercalation and deintercalation of lithium, and may include at least one selected from the group consisting of carbon-based active materials and silicon-based active materials. Specifically, the carbon-based active material may include one or more selected from the group consisting of artificial graphite, natural graphite, softened carbon, and hardened carbon. In addition, the silicon-based active material may include silicon (Si) and silicon oxide (SiO₂). x , 0 <x<2) 및 실리콘-탄소 복합체(Si / C composite)로 이루어진 군에서 선택된 적어도 1종을 포함할 수 있으며, 보다 구체적으로 실리콘-탄소 복합체를 포함할 수 있다.

[0138] The above-mentioned negative electrode active material may be included in an amount of 60% to 99% by weight based on the total weight of the negative electrode active material layer, preferably in an amount of 70% or more, 80% or more, 85% or more, or 90% or more by weight, and may also be included in an amount of 98% or less, 97% or less, or 95% or less by weight.

[0139] Meanwhile, the above-mentioned cathode active material layer may optionally further include a binder and / or a conductive material.

[0140] The above binder is a component that assists in the bonding between the conductive material, the active material, and the current collector, and can typically be added in an amount of 0.1% to 10% by weight based on the total weight of the negative active material layer, and can be included in an amount of 0.2% or more, 0.3% or more, or 0.5% or more by weight, and can also be included in an amount of 8.0% or less, or 5.0% or less by weight. Examples of such binders may include one or more selected from the group consisting of styrene-butadiene copolymer, acrylate styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, acrylic rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene propylene copolymer, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, ethylene propylenediene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, and polyvinyl alcohol. Among these, it may include one or more selected from the group consisting of styrene-butadiene copolymer, acrylate styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, carboxymethyl cellulose, hydroxypropylmethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylfluran, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, and cyanoethyl sucrose. Preferably, it is preferable to use carboxymethyl cellulose, hydroxypropylmethyl cellulose, hydroxypropyl cellulose, or a mixture thereof.

[0141] The above conductive material is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of 10% by weight or less, preferably 5% by weight or less, 3% by weight or less, 2% by weight or less, or 1% by weight or less based on the total weight of the negative electrode active material layer, and may also be included in an amount of 0.01% by weight or more, 0.05% by weight or more, 0.08% by weight or more, 0.1% by weight or more, or 0.3% by weight or more. Such conductive material is not particularly limited as long as it has conductivity without causing chemical changes in the battery, and for example, graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; conductive fibers such as carbon fiber or metal fiber; fluorinated carbon; metal powder such as aluminum or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives, etc. may be used.

[0142] The above-mentioned cathode active material layer may be manufactured by applying a cathode slurry composition, prepared by dissolving or dispersing a cathode active material and optionally a binder and a conductive material in a cathode slurry solvent, onto a cathode current collector and drying it, or by casting the cathode slurry composition onto a separate support and then laminating the film obtained by peeling it off from the support onto a cathode current collector.

[0143] The above cathode slurry solvent may include, for example, at least one selected from the group consisting of distilled water, NMP (N-methyl-2-pyrrolidone), ethanol, methanol, and isopropyl alcohol, preferably distilled water, in order to facilitate the dispersion of the cathode active material, binder, and / or conductive material. The solid content of the above cathode slurry composition may be 30% to 80% by weight, specifically 40% to 70% by weight.

[0144]

[0145] (2) Separator

[0146] The separator according to the present invention separates the negative electrode and the positive electrode and provides a pathway for the movement of lithium ions. It can be used without special limitations as long as it is commonly used as a separator in a lithium secondary battery. Specifically, the separator may be a porous polymer film, such as a porous polymer film made of a polyolefin-based polymer like an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof. 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.

[0147]

[0148] (3) Non-aqueous electrolyte

[0149] The non-aqueous electrolyte according to the present invention comprises a lithium salt, an organic solvent, and an additive. Examples of the non-aqueous electrolytes that can be used in the manufacture of lithium secondary batteries include organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, etc., but are not limited to these.

[0150] The above organic solvent may be used without special limitations as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. For example, the above organic solvent may include at least one selected from the group consisting of cyclic carbonate-based organic solvents, linear carbonate-based organic solvents, linear ester-based organic solvents, and cyclic ester-based organic solvents.

[0151] Specifically, the above organic solvents include ester-based solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether-based solvents such as dibutyl ether or tetrahydrofuran; ketone-based solvents such as cyclohexanone; aromatic hydrocarbon-based solvents such as benzene and fluorobenzene; carbonate-based solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); and alcohol-based solvents such as ethyl alcohol and isopropyl alcohol. Nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond-directing ring or ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes may be used. Among these, a carbonate-based solvent is preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery, and a low-viscosity linear carbonate-based compound (e.g., ethylmethyl carbonate, dimethyl carbonate or diethyl carbonate, etc.) is more preferred.

[0152] The above lithium salt can be used without special restrictions as long as it is a compound capable of providing lithium ions used in lithium secondary batteries. Specifically, the anions of the lithium salt may be one or more selected from the group consisting of F-, Cl-, Br-, I-, NO3-, N(CN)2-, BF4-, CF3CF2SO3-, (CF3SO2)2N-, (FSO2)2N-, CF3CF2(CF3)2CO-, (CF3SO2)2CH-, (SF5)3C-, (CF3SO2)3C-, CF3(CF2)7SO3-, CF3CO2-, CH3CO2-, SCN-, and (CF3CF2SO2)2N-, and the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2, etc., may be used. It is preferable to use the lithium salt within a concentration range of 0.1M to 4.0M, preferably 0.5M to 3.0M, and more preferably 1.0M to 2.0M. When the concentration of the lithium salt falls within the above range, the electrolyte has appropriate conductivity and viscosity, so it can exhibit excellent electrolyte performance and lithium ions can move effectively.

[0153] The additive according to the present invention may be included in a non-aqueous electrolyte to prevent the film from collapsing due to the decomposition of the non-aqueous electrolyte in a high-power environment, or for high-temperature stability or to suppress pre-expansion at high temperatures.

[0154] The above additive may include at least one selected from the group consisting of cyclic carbonate compounds, sulfate compounds, sulfone compounds, nitrile compounds, benzene compounds, lithium salt compounds, amine compounds, and silane compounds.

[0155] The above cyclic carbonate compound may be at least one selected from vinylene carbonate (VC) and vinyl ethylene carbonate (VEC).

[0156] The above sulfate-based compound may be at least one selected from ethylene sulfate (Esa), trimethylene sulfate (TMS), and methyl trimethylene sulfate (MTMS).

[0157] The above sulfone-based compound may be at least one selected from the group consisting of 1,3-propane sulfone (PS), 1,4-butane sulfone, ethen sulfone, 1,3-propene sulfone (PRS), 1,4-butene sulfone, and 1-methyl-1,3-propene sulfone.

[0158] 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).

[0159] 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.

[0160] The above additive may be included in the above non-aqueous electrolyte in an amount of 0.1 wt% or more, 0.2 wt% or more, 0.25 wt% or more, 0.3 wt% or more, or 0.4 wt% or more. Additionally, the above additive may be included in the above non-aqueous electrolyte in an amount of 5 wt% or less, 4 wt% or less, 3 wt% or less, 2 wt% or less, 1 wt% or less, or 0.8 wt% or less.

[0161] More specifically, the additive may be included in the non-aqueous electrolyte in an amount of 0.1 wt% to 5 wt%, specifically 0.2 wt% to 4 wt%, more specifically 0.2 wt% to 3 wt%, even more specifically 0.2 wt% to 0.8 wt%, and even more specifically 0.4 wt% to 0.8 wt%. When the content of the additive satisfies the above range, it is desirable in that it can prevent an increase in resistance by preventing side reactions caused by excessive use of the additive while improving the high-temperature performance of the lithium secondary battery.

[0162]

[0163] In addition, since the lithium secondary battery according to the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity retention rate, it is useful in 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).

[0164] Accordingly, according to another embodiment of the present invention, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same may be provided.

[0165] The above battery module or battery pack can be used as a power source for one or more medium-to-large devices, including a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0166] The present invention will be explained in more detail below through specific embodiments. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0167]

[0168] Example 1

[0169] (Manufacturing of the anode)

[0170] Cathode active material (LiNi 0.6 Co 0.1 Mn 0.3 A mixture was prepared by mixing O2, a conductive material (carbon nanotubes), and a binder (polyvinylidene fluoride, PVDF) in a weight ratio of 97.74:0.70:1.56 in N-methylpyrrolidone. Subsequently, an anode slurry was prepared by adding a compound represented by Chemical Formula 1-1 to the mixture. The compound represented by Chemical Formula 1-1 was added to the anode slurry at a content of 0.01 wt% based on the weight of the solid content of the anode slurry. Subsequently, the anode slurry was applied to one surface of an aluminum (Al) current collector with a thickness of 15 μm, dried, and then a roll press was performed to produce an anode.

[0171] (Manufacturing of lithium secondary batteries)

[0172] A cathode slurry was prepared by mixing a cathode active material (natural graphite), a conductive material (carbon black), and a binder (styrene-butadiene rubber (SBR)-carboxymethylcellulose (CMC)) in water at a weight ratio of 96.15:1.55:2.30. The cathode slurry was applied to one surface of a copper (Cu) current collector with a thickness of 15 μm and dried, and then a roll press was performed to produce a cathode.

[0173] As an organic solvent, a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 2:7:1 was used. A non-aqueous electrolyte was prepared by dissolving LiPF6 in the above organic solvent to a concentration of 1.2 M.

[0174] An electrode assembly was manufactured by interposing a polyethylene separator between the positive electrode and the negative electrode manufactured by the above-described method, and then the assembly was placed inside a battery case, and an electrolyte was injected into the battery case to manufacture a lithium secondary battery.

[0175]

[0176] Example 2

[0177] A positive electrode and a lithium secondary battery were manufactured in the same manner as in Example 1, except that a compound represented by the above chemical formula 1-1 was added to the positive electrode slurry at a content of 1% by weight based on the weight of the positive electrode slurry solid content.

[0178]

[0179] Example 3

[0180] A positive electrode and a lithium secondary battery were manufactured in the same manner as in Example 1, except that a compound represented by the above chemical formula 1-1 was added to the positive electrode slurry at a content of 5% by weight based on the weight of the positive electrode slurry solids.

[0181]

[0182] Example 4

[0183] A positive electrode and a lithium secondary battery were manufactured in the same manner as in Example 1, except that a compound represented by the above chemical formula 1-1 was added to the positive electrode slurry at a content of 10% by weight based on the weight of the positive electrode slurry solids.

[0184]

[0185] Example 5

[0186] A positive electrode and a lithium secondary battery were manufactured in the same manner as in Example 1, except that the compound represented by Chemical Formula 1-1 was not added to the positive electrode slurry, and the compound represented by Chemical Formula 1-2 was added at a content of 1% by weight based on the weight of the solid content of the positive electrode slurry.

[0187]

[0188] Example 6

[0189] A positive electrode and a lithium secondary battery were manufactured in the same manner as in Example 1, except that the compound represented by Chemical Formula 1-1 was not added to the positive electrode slurry, and the compound represented by Chemical Formula 1-3 was added at a content of 1% by weight based on the weight of the solid content of the positive electrode slurry.

[0190]

[0191] Example 7

[0192] A positive electrode and a lithium secondary battery were prepared in the same manner as in Example 1, except that the compound represented by Chemical Formula 1-1 was not added to the positive electrode slurry, and the compound represented by Chemical Formula 1-4 was added at a content of 1% by weight based on the weight of the solid content of the positive electrode slurry.

[0193]

[0194] Example 8

[0195] A positive electrode and a lithium secondary battery were prepared in the same manner as in Example 1, except that the compound represented by Chemical Formula 1-1 was not added to the positive electrode slurry, and the compound represented by Chemical Formula 1-5 was added at a content of 1% by weight based on the weight of the solid content of the positive electrode slurry.

[0196]

[0197] Example 9

[0198] A positive electrode and a lithium secondary battery were prepared in the same manner as in Example 1, except that the compound represented by Chemical Formula 1-1 was not added to the positive electrode slurry, and the compound represented by Chemical Formula 1-6 was added at a content of 1% by weight based on the weight of the solid content of the positive electrode slurry.

[0199]

[0200] Example 10

[0201] A positive electrode and a lithium secondary battery were manufactured in the same manner as in Example 1, except that the compound represented by Chemical Formula 1-1 was not added to the positive electrode slurry, and the compound represented by Chemical Formula 1-7 was added at a content of 1% by weight based on the weight of the solid content of the positive electrode slurry.

[0202]

[0203] Example 11

[0204] A positive electrode and a lithium secondary battery were prepared in the same manner as in Example 1, except that the compound represented by Chemical Formula 1-1 was not added to the positive electrode slurry, and the compound represented by Chemical Formula 1-8 was added at a content of 1% by weight based on the weight of the solid content of the positive electrode slurry.

[0205]

[0206] Example 12

[0207] A lithium secondary battery was manufactured in the same manner as in Example 1, except that ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 2:7:1 as organic solvents, and vinylene carbonate (VC) was added to make up 1% by weight to prepare a non-aqueous electrolyte.

[0208]

[0209] Example 13

[0210] A lithium secondary battery was manufactured in the same manner as in Example 1, except that ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 2:7:1 as organic solvents, and 1,3-propane sulfone (PS) was added to make up 1% by weight to prepare a non-aqueous electrolyte.

[0211]

[0212] Example 14

[0213] A lithium secondary battery was prepared in the same manner as in Example 1, except that ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 2:7:1 as organic solvents, and lithium difluorooxalatoborate (LiODFB) was added to make up 1% by weight to prepare a non-aqueous electrolyte.

[0214]

[0215] Example 15

[0216] A lithium secondary battery was manufactured in the same manner as in Example 1, except that ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 2:7:1 as organic solvents, and lithium difluorophosphate (LiDFP) was added to make up 1% by weight to prepare a non-aqueous electrolyte.

[0217]

[0218] Comparative Example 1

[0219] A positive electrode and a lithium secondary battery were prepared in the same manner as in Example 1, except that the compound represented by Chemical Formula 1-1 was not added to the positive electrode slurry.

[0220]

[0221] Comparative Example 2

[0222] A positive electrode and a lithium secondary battery were manufactured in the same manner as in Example 1, except that the compound represented by Chemical Formula 1-1 was not added to the positive electrode slurry, and the compound represented by Chemical Formula a was added at a content of 1% by weight based on the weight of the solid content of the positive electrode slurry.

[0223] [Chemical formula a]

[0224]

[0225]

[0226] Comparative Example 3

[0227] A positive electrode and a lithium secondary battery were manufactured in the same manner as in Example 1, except that the compound represented by Chemical Formula 1-1 was not added to the positive electrode slurry, and the compound represented by Chemical Formula b was added at a content of 1% by weight based on the weight of the solid content of the positive electrode slurry.

[0228] [Chemical formula b]

[0229]

[0230]

[0231] Comparative Example 4

[0232] A lithium secondary battery was prepared in the same manner as in Example 1, except that ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed as organic solvents in a volume ratio of 2:7:1, and a compound represented by Chemical Formula 1-1 was added to an amount of 1% by weight to prepare a non-aqueous electrolyte.

[0233] Additives included in the positive electrode active material layer Additives included in the electrolyte Type Content (weight%) Type Content (weight%) Example 1 Chemical Formula 1-10.01 -- Example 2 Chemical Formula 1-11 -- Example 3 Chemical Formula 1-15 -- Example 4 Chemical Formula 1-110 -- Example 5 Chemical Formula 1-21 -- Example 6 Chemical Formula 1-31 -- Example 7 Chemical Formula 1-41 -- Example 8 Chemical Formula 1-51 -- Example 9 Chemical Formula 1-61 -- Example 10 Chemical Formula 1-71 -- Example 11 Chemical Formula 1-81 -- Example 12 Chemical Formula 1-11VC0.5 Example 13 Chemical Formula 1-11PS0.5 Example 14 Chemical Formula 1-11LiODFB0.5 Example 15 Chemical Formula 1-11 LiDFP 0.5 Comparative Example 1 ---- Comparative Example 2 Chemical Formula a1 -- Comparative Example 3 Chemical Formula b1 -- Comparative Example 4 -- Chemical Formula 1-11

[0234]

[0235] Experimental Example 1: Evaluation of High-Temperature Cycle Characteristics

[0236] The lithium secondary batteries of Examples 1 to 15 and Comparative Examples 1 to 4 prepared above were charged to 4.4V and 0.05C at 45℃ under CC / CV and 0.33C conditions using an electrochemical charge / discharger, and then discharged to 2.5V under CC and 0.33C conditions, with 200 charge / discharge cycles performed as one cycle.

[0237] (1) Capacity retention rate

[0238] The capacity retention rate was calculated using the following formula, and the results are shown in Table 2 below.

[0239] Capacity Retention Rate (%) = (Discharge Capacity after 200 cycles / Discharge Capacity after 1 cycle) × 100

[0240] (2) Resistance increase rate

[0241] After the aforementioned 1 cycle of charging and discharging, the discharge capacity after 1 cycle was measured using an electrochemical charge / discharger, and after adjusting the SOC to 50%, a 2.5C pulse was applied for 10 seconds, and the initial resistance was calculated through the difference between the voltage before and after the pulse application. Subsequently, the final resistance was calculated through the voltage difference after 200 cycles using the same method, and the resistance increase rate was calculated using the following formula and is shown in Table 2 below.

[0242] Resistance Increase Rate (%) = {(Final Resistance - Initial Resistance) / Initial Resistance} × 100

[0243] Capacitance Retention Rate (%) Resistance Increase Rate (%) Example 194.0 20.1 Example 294.7 18.9 Example 394.3 19.5 Example 494.1 20.0 Example 594.2 19.2 Example 694.3 19.5 Example 794.5 19.0 Example 894.7 20.0 Example 994.2 19.5 Example 1094.1 19.5 Example 1194.5 19.7 Example 1295.0 19.0 Example 1394.9 18.5 Example 1495.1 17.9 Example 1595.2 18.0 Comparative Example 150.1 55.9 Comparative Example 262.1 39.5 Comparative Example 369.144.9 Comparative Example 467.540.1

[0244]

[0245] Referring to Table 2 above, it can be seen that Examples 1 to 15, which include a compound represented by Chemical Formula 1 in the positive active material layer, show significantly improved capacity retention rate and resistance increase rate compared to Comparative Examples 1 to 4.

[0246] Specifically, it can be confirmed that Comparative Example 2 has significantly lower high-temperature cycle characteristics compared to the Examples, which is believed to be because the side reactions with the electrolyte increased due to the protons of the compound represented by chemical formula a included in Comparative Example 2, thereby accelerating the degradation of the secondary battery.

[0247] In addition, it can be confirmed that Comparative Example 4 exhibits significantly lower high-temperature cycle characteristics compared to Examples 1 to 4, even though the same compounds as Examples 1 to 4 were used in the manufacture of the secondary battery. This is believed to be because when the compound represented by Formula 1-1 is used as an additive to a non-aqueous electrolyte rather than as a positive electrode active material, the performance of the positive electrode is degraded due to reductive decomposition caused by the high reactivity of the compound represented by Formula 1-1.

[0248]

[0249] Experimental Example 2: Evaluation of High-Temperature Storage Characteristics

[0250] The lithium secondary batteries of Examples 1 to 15 and Comparative Examples 1 to 4 prepared above were charged to 4.4V and 0.05C under CC / CV and 0.33C conditions using an electrochemical charge / discharger, and discharged to 2.5V under CC and 0.33C conditions to perform initial charge and discharge. Afterward, they were charged to 4.4V and 0.05C under CC / CV and 0.33C conditions at 25℃, and then stored at 60℃ for 12 weeks.

[0251] (1) Capacity retention rate

[0252] After 12 weeks of storage, the lithium secondary battery was charged to 4.4V and 0.05C at 25℃ under CC / CV and 0.33C conditions using an electrochemical charger / discharger, and discharged to 2.5V at CC and 0.33C to measure the capacity at discharge. Subsequently, the capacity retention rate was calculated according to the following formula, and the results are shown in Table 3 below.

[0253] Capacity Retention Rate (%) = (Discharge Capacity after 12 Weeks of Storage / Initial Discharge Capacity) × 100

[0254] (2) Resistance increase rate

[0255] After the initial charge and discharge described above, the capacity was checked at room temperature, and the SOC was charged to 50% based on the discharge capacity. The initial resistance was calculated by measuring the difference in voltage drop during the discharge at 2.5C current for 10 seconds, and the final resistance was calculated by measuring the resistance in the same way after storage at 60℃ for 12 weeks. Subsequently, the resistance increase rate was calculated using the following formula, and the results are shown in Table 3 below.

[0256] Resistance Increase Rate (%) = {(Final Resistance - Initial Resistance) / Initial Resistance} × 100

[0257] Capacitance Retention Rate (%) Resistance Increase Rate (%) Example 194.7 23.7 Example 295.1 21.1 Example 394.9 23.0 Example 494.5 23.5 Example 594.8 21.6 Example 694.9 21.8 Example 794.8 22.0 Example 894.5 21.5 Example 995.0 22.7 Example 1094.8 21.9 Example 1194.7 22.8 Example 1295.1 20.9 Example 1395.3 21.0 Example 1495.3 20.9 Example 1595.1 20.7 Comparative Example 151.9 70.2 Comparative Example 272.1 47.8 Comparative Example 360.555.1 Comparative Example 470.849.5

[0258]

[0259] Referring to Table 3 above, it can be seen that Examples 1 to 15, which include a compound represented by Chemical Formula 1 in the positive electrode active material layer, have significantly superior high-temperature storage characteristics compared to Comparative Examples 1 to 4.

[0260] Specifically, it can be confirmed that Comparative Examples 1 and 2 exhibit significantly lower high-temperature cycle characteristics compared to the Examples. This is attributed to the fact that in Comparative Example 1, the oxidative decomposition of the electrolyte at the anode increased, causing the transition metal of the active material to leach out. Additionally, in Comparative Example 2, it is believed that the side reactions with the electrolyte increased due to the protons of the compound represented by chemical formula a, which in turn reduced the durability of the film formed on the anode.

[0261] In addition, it can be confirmed that Comparative Example 4 exhibits significantly lower high-temperature storage characteristics compared to Examples 1 to 4, even though the same compounds as Examples 1 to 4 were used in the manufacture of the secondary battery. This is believed to be because when the compound represented by Formula 1-1 is used as an additive to a non-aqueous electrolyte rather than as a positive electrode active material, it is difficult to form a film on the positive electrode due to reductive decomposition caused by the high reactivity of the compound represented by Formula 1-1.

Claims

1. Includes a positive current collector and a positive active material layer located on the positive current collector, and The above positive electrode active material layer comprises a positive electrode active material and a compound represented by the following chemical formula 1: [Chemical Formula 1] In the above chemical formula 1, R1 is an alkyl group having 1 to 10 carbon atoms or an alkyl group having 1 to 10 carbon atoms substituted with one or more fluorines, and R 21 , R 22 , R 23 , and R 24 are independently hydrogen or alkyl groups having 1 to 5 carbon atoms, and L is a direct bond, an ether group (*-O-*), or an ester group (*-C(=O)O-*).

2. In Claim 1, The compound represented by the above chemical formula 1 is an anode comprising a compound represented by the following chemical formula 1-A: [Chemical Formula 1-A] In the above chemical formula 1-A, R1 and L are as defined in Equation 1 above.

3. In Claim 1, An anode in which R1 of the above chemical formula 1 is an alkyl group having 1 to 5 carbon atoms or an alkyl group having 1 to 5 carbon atoms substituted with one or more fluorines.

4. In Claim 1, An anode in which R1 of the above chemical formula 1 is an alkyl group having 1 to 5 carbon atoms or a perfluoroalkyl group having 1 to 5 carbon atoms.

5. In Claim 1, An anode comprising one or more selected from the group consisting of compounds represented by the above chemical formula 1 to 1-8: [Chemical Formula 1-1] [Chemical Formula 1-2] [Chemical Formula 1-3] [Chemical Formula 1-4] [Chemical Formula 1-5] [Chemical Formula 1-6] [Chemical Formula 1-7] [Chemical Formula 1-8] .

6. In Claim 1, The compound represented by the above chemical formula 1 is an anode included in the above anode active material layer in an amount of 0.001 weight% to 10 weight%.

7. Anode according to Claim 1; cathode; Separator; and A lithium secondary battery containing a non-aqueous electrolyte.

8. In Claim 7, The above-mentioned non-aqueous electrolyte is a lithium secondary battery comprising a lithium salt, an organic solvent, and an additive.

9. In Claim 8, A lithium secondary battery comprising at least one additive selected from the group consisting of cyclic carbonate compounds, sulfate compounds, sulfone compounds, nitrile compounds, benzene compounds, lithium salt compounds, amine compounds, and silane compounds.

10. In Claim 8, A lithium secondary battery comprising at least one selected from the group consisting of a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, a linear ester-based organic solvent, and a cyclic ester-based organic solvent.

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