Positive electrode slurry composition, positive electrode comprising same, and lithium secondary battery

Abstract

The present invention relates to a positive electrode slurry composition, a positive electrode comprising the same, and a lithium secondary battery, and particularly to a positive electrode slurry composition for a lithium secondary battery, a positive electrode for a lithium secondary battery comprising the same, and a lithium secondary battery, the positive electrode slurry composition comprising a positive electrode active material, a film-forming additive, and a solvent, wherein the film-forming additive is a compound represented by Formula 1.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2024-0125221, filed on September 12, 2024, and Korean Patent Application No. 10-2025-0124482, filed on September 2, 2025, the disclosures of which are incorporated herein by reference. Technical Field

[0003] This invention relates to a positive electrode slurry composition, a positive electrode, and a lithium secondary battery, wherein, by including the positive electrode slurry composition, gas generation caused by side reactions between the positive electrode and the electrolyte is reduced. Background Technology

[0004] With the development of technology and the increasing demand for mobile devices, the demand for secondary batteries as an energy source has increased significantly. Among these secondary batteries, lithium secondary batteries with high energy density, high operating potential, long cycle life and low self-discharge rate have been commercialized and widely used.

[0005] As the application of lithium-ion batteries expands to include not only portable power sources for mobile phones, laptops, digital cameras, and camcorders, but also medium and large power sources for power tools, electric bicycles, hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs), high operating voltages are required to achieve high energy density.

[0006] However, when lithium-ion batteries operate continuously at high voltages, the electrolyte is not only depleted due to the oxidative decomposition reactions of the positive electrode and the electrolyte itself, but also suffers from problems such as gas generation and the dissolution of transition metals from the positive electrode due to the collapse of the passivation film on the electrode surface. Therefore, the battery's long-life performance is reduced. These problems are exacerbated or accelerated by the exothermic reactions that occur during battery operation.

[0007] Therefore, there is a need to develop a lithium secondary battery that can suppress gas generation and dissolution of transition metals from the positive electrode caused by electrolyte side reactions by forming a stable passivation film on the electrode surface during high-voltage operation, thereby achieving high energy density. Summary of the Invention

[0008] [Technical Issues]

[0009] One aspect of the present invention provides a cathode slurry composition comprising a uracil compound, said uracil compound being capable of first forming a highly durable film on the surface of the cathode.

[0010] Furthermore, another aspect of the present invention provides a positive electrode comprising a layer of positive electrode material mixture, the layer comprising a film-forming additive capable of forming a highly durable film on the surface of the positive electrode.

[0011] Furthermore, another aspect of the present invention provides a lithium secondary battery including the above-described positive electrode.

[0012] [Technical Solution]

[0013] [1] The present invention provides a positive electrode slurry composition for lithium secondary batteries, comprising a positive electrode active material, a film-forming additive and a solvent, wherein the film-forming additive is a compound represented by Formula 1.

[0014] [Formula 1]

[0015] In Equation 1, R1 is -SO2F, -OSO2N (R a (R) b -SO2R c -OLi or -OR', where R a and R b Each is independently an alkyl group having 1 to 5 carbon atoms, R c It is an unsubstituted or fluorinated alkyl group having 1 to 5 carbon atoms, and R' is an alkyl group having 1 to 10 carbon atoms.

[0016] [2] The present invention provides the positive electrode slurry composition for lithium secondary batteries described in [1] above, wherein, in Formula 1, R1 is -SO2F, -OSO2N(R a (R) b ) or -SO2R c , where R a and R b Each is independently an alkyl group having 1 to 5 carbon atoms, and R c It is an unsubstituted or fluorinated alkyl group having 1 to 5 carbon atoms.

[0017] [3] The present invention provides the positive electrode slurry composition for lithium secondary batteries described in [1] or [2] above, wherein, in Formula 1, R1 is -SO2F, -OSO2N(R a (R) b ) or -SO2R c , where R a and R b Each is independently an alkyl group having 1 to 3 carbon atoms, and R c It is an unsubstituted or fluorinated alkyl group having 1 to 3 carbon atoms.

[0018] [4] The present invention provides a positive electrode slurry composition for lithium secondary batteries of at least one of [1] to [3] above, wherein the compound represented by formula 1 is at least one of the compounds represented by formula 1A to 1G: [Formula 1A]

[0019] [Formula 1B]

[0020] [Formula 1C]

[0021] [Formula 1D]

[0022] [Formula 1E]

[0023] [Formula 1F]

[0024] [Formula 1G] .

[0025] [5] The present invention provides a positive electrode slurry composition for lithium secondary batteries of at least one of [1] to [4] above, wherein the content of the film-forming additive is from 0.004% by weight to 10% by weight based on the total weight of the solid components of the positive electrode slurry composition.

[0026] [6] The present invention provides a positive electrode slurry composition for lithium secondary batteries of at least one of [1] to [5] above, wherein the content of the film-forming additive is from 0.1% to 8.0% by weight based on the total weight of the solid components of the positive electrode slurry composition.

[0027] [7] The present invention provides a positive electrode slurry composition for lithium secondary batteries according to at least one of [1] to [6] above, wherein the positive electrode active material comprises a compound represented by formula 2: [Equation 2] Li 1+a Ni x Co y M 1 z M 2 w O2 In Equation 2, M 1 It is manganese (Mn), aluminum (Al), or a combination thereof. M 2is at least one selected from the group consisting of Al, zirconium (Zr), tungsten (W), titanium (Ti), magnesium (Mg), calcium (Ca) or strontium (Sr), and 0≤a≤0.5, 0<x<1.0, 0<y≤0.4, 0<z≤0.4, 0≤w≤0.1, and x+y+z+w can be 1.

[0028] [8] The present invention provides the positive electrode slurry composition for a lithium secondary battery according to at least one of the above [1] to [7], wherein the positive electrode slurry composition for a lithium secondary battery further comprises at least one of a conductive agent, a binder and a thickener.

[0029] [9] The present invention provides a positive electrode for a lithium secondary battery, comprising a positive electrode material mixture layer, the positive electrode material mixture layer comprising a positive electrode active material and a film-forming additive, wherein the film-forming additive is a compound represented by Formula 1: [Formula 1]

[0030] In Formula 1, R1 is -SO2F, -OSO2N(R a )(R b )、-SO2R c 、-OLi or -OR', wherein R a and R b are each independently an alkyl group having 1 to 5 carbon atoms, R c is an alkyl group having 1 to 5 carbon atoms that is unsubstituted or substituted with fluorine, and R' is an alkyl group having 1 to 10 carbon atoms.

[0031]

[10] The present invention provides the positive electrode according to the above [9], wherein the positive electrode material mixture layer comprises a urea-containing film.

[0032]

[11] The present invention provides a method for preparing a positive electrode for a secondary battery, the method comprising: applying a positive electrode slurry composition onto a positive electrode current collector; and forming a positive electrode material mixture layer by drying and rolling the positive electrode slurry composition, wherein the positive electrode slurry composition is the positive electrode slurry composition according to the above [1].[]

[0033]

[12] The present invention provides a lithium secondary battery, comprising: the positive electrode according to the above [9]; a negative electrode facing the positive electrode; and an electrolyte.

[0034] [Advantageous Effects]

[0035] As described above, since the positive electrode slurry composition for a lithium secondary battery of the present invention comprises a uracil-based compound as a film-forming additive, it can prevent side reactions at the interface between the positive electrode and the electrolyte by first forming a robust urea-containing film on the surface of the positive electrode during initial charging, and inhibit oxygen desorption from the positive electrode.

[0036] Furthermore, lithium secondary batteries including the aforementioned cathode can effectively improve electrochemical performance, such as high-temperature lifetime characteristics and high-temperature storage performance, by suppressing gas generation during operation and the dissolution of transition metals from the cathode. Detailed Implementation

[0037] It should be understood that the words or terms used in the specification and claims should not be construed as having the meanings defined in commonly used dictionaries. It should also be understood that, based on the principle that the inventors can appropriately define the meanings of words or terms to best interpret the invention, the words or terms should be interpreted as having meanings consistent with their meanings in the context of the relevant technology and technical ideas of the invention.

[0038] The present invention will be described in detail below.

[0039] The positive electrode slurry composition of the present invention, the positive electrode for a lithium secondary battery comprising a layer of a positive electrode material mixture containing a positive electrode active material and a film-forming additive, the method for preparing the positive electrode, and the lithium secondary battery comprising at least one of the following configurations, and may include any combination of technically possible configurations among the following configurations.

[0040] Positive electrode slurry composition for lithium secondary batteries

[0041] The positive electrode slurry composition for lithium secondary batteries of the present invention comprises: a positive electrode active material, a film-forming additive, and a solvent, wherein the film-forming additive may be a compound represented by Formula 1.

[0042] [Formula 1]

[0043] In Equation 1, R1 is -SO2F, -OSO2N (R a (R) b -SO2R c -OLi or -OR', where R a and R b Each is independently an alkyl group having 1 to 5 carbon atoms, R c It is an unsubstituted or fluorinated alkyl group having 1 to 5 carbon atoms, and R' is an alkyl group having 1 to 10 carbon atoms.

[0044] (1) Positive electrode active material

[0045] The positive electrode active material of the present invention is a compound capable of reversibly inserting and deintercalating lithium, wherein the positive electrode active material may specifically include a lithium composite metal oxide, wherein the lithium composite metal oxide includes lithium and at least one metal (e.g., cobalt, manganese, nickel or aluminum).

[0046] Specifically, the lithium composite metal oxide may include: lithium-cobalt oxides (e.g., LiCoO₂, etc.), lithium-manganese oxides (e.g., LiMnO₂, LiMn₂O₄, etc.), lithium-nickel oxides (e.g., LiNiO₂, etc.), lithium-nickel-manganese oxides (e.g., LiNi 1-Y Mn Y O₂ (where 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 (where 0<Y1<1), etc.), lithium-manganese-cobalt oxides (e.g., LiCo 1-Y2 Mn Y2 O₂ (where 0<Y2<1), LiMn 2- Z1 Co Z1 O₄ (where 0<Z1<2), etc.), lithium-nickel-manganese-cobalt oxides or Li(Ni p1 Co q1 Mn r2 )O₄ (where 0<p1<2, 0<q1<2, 0<r2<2, and p1+q1+r2=2), etc.), or lithium-nickel-cobalt-transition metal (M) oxides (e.g., Li(Ni p2 Co q2 Mn r3 M s2 )O₂ (where M is selected from the group consisting of aluminum (Al), iron (Fe), vanadium (V), chromium (Cr), titanium (Ti), tantalum (Ta), magnesium (Mg) and molybdenum (Mo), p2, q2, r3 and s2 are atomic fractions of each independent element, wherein 0<p2<1, 0<q2<1, 0<r3<1, 0<S2<1, and p2+q2+r3+S2=1), etc.), and may include any one or two or more of the compounds.

[0047] Among these materials, in terms of improving the capacity characteristics and stability of the battery, the positive electrode active material may include at least one selected from lithium-cobalt oxides, lithium-manganese based oxides, or lithium-nickel-manganese-cobalt based oxides represented by Formula 2 below.

[0048] [Formula 2]

[0049] Li 1+a Ni x Co y M 1 z M 2 w O₂

[0050] In Formula 2, M 1 is manganese (Mn), aluminum (Al) or a combination thereof, M 2 is at least one selected from the group consisting of Al, zirconium (Zr), tungsten (W), titanium (Ti), magnesium (Mg), calcium (Ca) and strontium (Sr), and 0≤a≤0.5, 0<x<1.0, 0<y≤0.4, 0<z≤0.4, 0≤w≤0.1, and x+y+z+w can be 1.

[0051] 1+a represents the atomic fraction of lithium in the lithium transition metal oxide, wherein a can satisfy 0≤a≤0.5, preferably 0≤a≤0.2, more preferably 0≤a≤0.1.

[0052] x represents the atomic fraction of nickel in the total transition metal elements of the lithium transition metal oxide, wherein x can satisfy 0<x<1.0, particularly 0.55<x≤0.98, more particularly 0.6≤x≤0.98, even more particularly 0.6≤x≤0.95.

[0053] y represents the atomic fraction of cobalt in the total transition metal elements of the lithium transition metal oxide, wherein y can satisfy 0<y≤0.4, particularly 0<y≤0.3, more particularly 0.05≤y≤0.3.

[0054] z represents the atomic fraction of M 1 elements in the total transition metal elements of the lithium transition metal oxide, wherein z can satisfy 0<z≤0.4, preferably 0<z≤0.3, more preferably 0.01≤z≤0.3.

[0055] w represents the atomic fraction of M 2 elements in the total transition metal elements of the lithium transition metal oxide, wherein w can satisfy 0<w≤0.1, preferably 0<w≤0.05, more preferably 0<w≤0.02.

[0056] Specifically, in order to obtain a high-capacity battery, the positive electrode active material may include a lithium composite transition metal oxide having a Ni content of 0.55 atm% or more based on the total number of metal elements other than lithium. More specifically, the positive electrode active material may include Li(Ni 0.6 Mn 0.2 Co 0.2 )O₂, Li(Ni 0.6 Mn 0.3 Co 0.1 )O₂, Li(Ni 0.7 Mn 0.15 Co 0.15 )O₂, Li(Ni 0.7 Mn 0.2 Co 0.1 )O₂, Li(Ni 0.8 Mn0.1 Co 0.1 O2, Li(Ni) 0.8 Co 0.15 Al 0.05 O2, Li(Ni) 0.86 Mn 0.07 Co 0.05 Al 0.02 O2 or Li(Ni) 0.90 Mn 0.05 Co 0.05 )O2.

[0057] Based on the total weight of the solid components contained in the cathode slurry composition, the content of the cathode active material can be from 80% by weight to 108% by weight, more specifically from 85% by weight to 108% by weight. When the content of the cathode active material is within the above range, excellent capacity characteristics can be ensured, and excellent flowability, conductivity, or physical properties of the cathode slurry composition can be obtained.

[0058] (2) Film-forming additives

[0059] The cathode slurry composition of the present invention may include film-forming additives, enabling the formation of a urea-based film on the cathode surface.

[0060] Film-forming additives can be compounds represented by Formula 1 below.

[0061] [Formula 1]

[0062] In Equation 1, R1 is -SO2F, -OSO2N (R a (R) b -SO2R c -OLi or -OR', where R a and R b Each is independently an alkyl group having 1 to 5 carbon atoms, R c It is an unsubstituted or fluorinated alkyl group having 1 to 5 carbon atoms, and R' is an alkyl group having 1 to 10 carbon atoms.

[0063] Specifically, during the initial charging period, the ring structure of the compound represented by Formula 1 decomposes as the -NC- single bond in the -NC=O part breaks, and then reacts with the carbonate compound as the electrolyte solvent and / or the Lewis acid (HF) contained in the electrolyte. Thus, the compound represented by Formula 1, which contains a uracil group in its structure, can form a polymer film containing one or more polycarbonate units on the electrode surface.

[0064] When simply using the compound represented by Formula 1 as an electrolyte additive, the film-forming effect on the positive electrode surface may be reduced because the compound represented by Formula 1 is consumed first on the negative electrode surface during initial charging and discharging. Furthermore, due to the preemptive decomposition of the compound represented by Formula 1 in the electrolyte induced at the negative electrode, a film forms on the negative electrode surface, resulting in increased initial resistance and insufficient formation of a positive electrode film. Additionally, there is the problem that uracil, reduced to a free radical form at the negative electrode, is re-oxidized on the positive electrode surface, generating byproducts that form complexes with metals dissolved from the positive electrode, subsequently causing another byproduct upon migration to the negative electrode.

[0065] To address these issues, the present invention incorporates a compound represented by Formula 1 as a film-forming additive into the positive electrode active material slurry. Specifically, in this invention, by incorporating the compound represented by Formula 1 as an additive into the positive electrode active material slurry, a urea-containing film can be preemptively formed on the positive electrode surface during battery operation. This not only prevents the dissolution of metal elements but also allows for the initial film formation on the positive electrode surface, thus preventing excessive film formation on the negative electrode surface. This prevents an increase in initial resistance and simultaneously improves the high-voltage performance of the battery cell.

[0066] Therefore, significant improvements can be made to the electrochemical performance of lithium secondary batteries (such as high-temperature lifetime characteristics and high-temperature storage performance) because side reactions at the interface between the cathode and electrolyte can be effectively prevented, while the increase in initial resistance during battery operation can be reduced, the oxidative decomposition reaction of the electrolyte can be suppressed, and the oxygen desorption and transition metal dissolution of the cathode active material can be suppressed.

[0067] In particular, since the compounds represented by Formula 1 are substituted with functional groups containing sulfonyl (-SO2-) or oxygen (-O-) as substituents (R1) that are directly bonded to the uracil group (core), a resonance structure is formed between the uracil group and the functional group, thus exhibiting the advantage of high inter-electron interaction. For example, compared to the use of uracil compounds directly substituted with alkyl, fluorine, or amino groups (e.g., compounds represented by Formula 3 below) as film-forming additives, the advantage of containing the compounds represented by Formula 1 of the present invention is that, by promoting the ring-opening reaction of the uracil group, a robust urea-containing film with enhanced lithium-ion properties can be formed more quickly on the cathode surface.

[0068] [Formula 3]

[0069] (In Formula 3, Ro is a fluorine-substituted or unsubstituted alkyl group, -F or -NH2)

[0070] Specifically, in Equation 1, R1 is -SO2F, -OSO2N (Ra (R) b ) or -SO2R c , where R a and R b Each is independently an alkyl group having 1 to 5 carbon atoms, and R c It can be an unsubstituted or fluorinated alkyl group having 1 to 5 carbon atoms.

[0071] Furthermore, in Equation 1, R1 is -SO2F, -OSO2N (R a (R) b ) or -SO2R c , where R a and R b Each is independently an alkyl group having 1 to 3 carbon atoms, and R c It can be an unsubstituted or fluorinated alkyl group having 1 to 3 carbon atoms.

[0072] Specifically, the compound represented by Formula 1 may be at least one of the compounds represented by Formulas 1A to 1G below, and may preferably be at least one of the compounds represented by Formulas 1A to 1D and 1G below that contain a sulfonyl group in their structure.

[0073] [Formula 1A]

[0074] [Formula 1B]

[0075] [Formula 1C]

[0076] [Formula 1D]

[0077] [Formula 1E]

[0078] [Formula 1F]

[0079] [Formula 1G]

[0080] Based on the total weight of the solid components in the cathode slurry composition, the content of the film-forming additive can be 0.004% by weight or more, 0.01% by weight or more, 0.03% by weight or more, 0.05% by weight or more, 0.07% by weight or more, 0.09% by weight or more, or 0.1% by weight or more. Furthermore, based on the total weight of the solid components in the cathode slurry composition, the content of the film-forming additive can be 10% by weight or less, 9.0% by weight or less, 8.0% by weight or less, 7.0% by weight or less, 6.0% by weight or less, or 5.0% by weight or less. When the amount of film-forming additive meets the above ranges, a robust film can be formed on the cathode surface to suppress the oxidative decomposition reaction between the cathode and the electrolyte, while preventing side reactions caused by the film-forming additive, reducing gas generation, and suppressing oxygen desorption from the cathode. The above numerical ranges can be combined without limitation, and the content range of the film-forming additive can specifically be 0.004 wt% to 10 wt%, 0.01 wt% to 8 wt%, 0.1 wt% to 8 wt%, or 0.1 wt% to 5.0 wt%. That is, when the amount of film-forming additive is 0.004 wt% or more, a robust film can be formed on the positive electrode surface during battery operation; when the amount of film-forming additive is 10 wt% or less, side reactions caused by the film-forming additive can be prevented, and the increase in resistance caused by the formation of a thick film on the positive electrode surface can be prevented.

[0081] (3) Solvent

[0082] In the positive electrode slurry composition of the present invention, the solvent may be an organic solvent and / or an aqueous solvent commonly used in the art.

[0083] Specifically, the organic solvent may be at least one of N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), isopropanol, acetone, methoxypropyl acetate, butyl acetate, glycolic acid, butyl acetate, butanediol, polymethylalkylsiloxane, alkylbenzene, propylene glycol, xylene, monophenylethylene glycol, aralkyl-modified polymethylalkylsiloxane, polyether-modified polydimethylsiloxane copolymer, polyether-modified polydimethylsiloxane copolymer, polyacrylate, alkylbenzene, diisobutyl ketone, organically modified polysiloxane, butanol, isobutanol, modified polyacrylate, modified polyurethane, and polysiloxane-modified polymers. Furthermore, the aqueous solvent may include water.

[0084] Considering the coating thickness, manufacturing yield, and processability of the cathode material mixture layer, the amount of solvent used can be sufficient and there are no particular limitations if the cathode slurry composition can be adjusted to have an appropriate viscosity.

[0085] If desired, the positive electrode slurry composition for lithium secondary batteries of the present invention may optionally further comprise at least one of a conductive agent, a binder, and a thickener.

[0086] (4) Conductive agent

[0087] Specifically, the conductive agent is used to provide conductivity to the electrode. Any conductive agent can be used without particular limitation, provided it has suitable electronic conductivity and does not cause adverse chemical changes in the battery. Specific examples of conductive agents include: carbon black, such as acetylene black (or Denka black), Ketjen black, channel black, furnace black, lamp black, or thermally cracked carbon black; graphite powder, such as natural graphite, artificial graphite, or graphite with a well-developed crystal structure; conductive fibers, such as carbon fibers or metal fibers; conductive powders, such as fluorocarbon powders, aluminum powder, and nickel powder; conductive whiskers, such as zinc oxide whiskers and potassium titanate whiskers; conductive metal oxides, such as titanium oxide; or polyphenylene derivatives, and any one or a mixture of two or more of them can be used.

[0088] Based on the total weight of the solid components contained in the positive electrode slurry composition, the content of the conductive agent can be from 0.1% by weight to 10.0% by weight, preferably from 1.0% by weight to 8.0% by weight. When the amount of conductive agent meets the above range, the conductivity of the positive electrode can be improved, and the reduction of the flexibility of the positive electrode can be prevented.

[0089] (5) Adhesive

[0090] Adhesives improve the adhesion between positive electrode active material particles and the adhesion between the positive electrode active material and the current collector. Examples of adhesives include any one or a mixture of two or more of the following: fluoropolymer adhesives, including polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE); rubber adhesives, including styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, or styrene-isoprene rubber; cellulose adhesives, including carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, or regenerated cellulose; polyol adhesives, including polyvinyl alcohol; polyolefin adhesives, including polyethylene or polypropylene; polyimide adhesives; polyester adhesives; and silane adhesives.

[0091] Based on the total weight of the solid components of the cathode slurry composition, the binder content in the cathode material mixture layer can be from 0.1% to 15% by weight, preferably from 0.1% to 10% by weight. When the amount of binder is at the above level, the reduction in cathode capacity can be prevented, while ensuring sufficient adhesion between the cathode active material and the cathode current collector.

[0092] (6) Thickener

[0093] In addition, thickeners can provide appropriate viscosity to the cathode slurry composition, thereby ensuring the stability of the cathode slurry composition, and can reduce the re-aggregation of solid components when coating the cathode current collector with the cathode slurry composition, thereby improving surface defects.

[0094] Thickeners may include carboxymethyl cellulose (CMC).

[0095] Based on the total weight of the solid components in the cathode slurry composition, the thickener content can be from 0.5% by weight to 5% by weight. If the amount of thickener is less than 0.5% by weight, the cathode slurry composition will flow downwards like water due to its low viscosity, and therefore the cathode current collector may not be able to be coated with the cathode slurry composition; if the amount of thickener is greater than 5% by weight, the cathode slurry composition will become highly viscous, making it difficult to form a uniform coating.

[0096] The viscosity of the cathode slurry composition of the present invention is not particularly limited and can vary depending on the amount of solid components in the composition. However, considering the ease of coating process and phase stability of the cathode slurry composition, the viscosity at 25°C can be 1000 cP or more or 4500 cP or more.

[0097] positive electrode

[0098] Furthermore, the present invention includes a positive electrode, specifically, a positive electrode for a lithium secondary battery.

[0099] Specifically, the present invention provides a positive electrode for a lithium secondary battery, which may include a positive electrode material mixture layer, the positive electrode material mixture layer including a positive electrode active material and a film-forming additive, wherein the film-forming additive is a compound represented by Formula 1.

[0100] That is, the positive electrode material mixture layer can be formed by the above-described positive electrode slurry composition of the present invention.

[0101] The content of the positive electrode active material in the positive electrode material mixture layer can be from 80% to 99% by weight, more specifically from 85% to 98% by weight.

[0102] Film-forming additives can be compounds represented by Formula 1.

[0103] Based on the total weight of the cathode material mixture layer, the content of the film-forming additive can be 0.004% by weight or more, 0.01% by weight or more, 0.03% by weight or more, 0.05% by weight or more, 0.07% by weight or more, 0.09% by weight or more, or 0.1% by weight or more. Furthermore, based on the total weight of the cathode material mixture layer, the content of the film-forming additive can be 10% by weight or less, 9.0% by weight or less, 8.0% by weight or less, 7.0% by weight or less, 6.0% by weight or less, or 5.0% by weight or less. When the amount of film-forming additive meets the above ranges, since a robust film is formed on the cathode surface, the oxidative decomposition reaction between the cathode and the electrolyte can be suppressed, while preventing side reactions caused by the film-forming additive, reducing gas generation, and suppressing oxygen desorption from the cathode. The above numerical ranges can be combined without limitation, and the content range of the film-forming additive can specifically be 0.004 wt% to 10 wt%, 0.01 wt% to 8 wt%, 0.1 wt% to 8 wt%, or 0.1 wt% to 5.0 wt%. That is, when the amount of film-forming additive is 0.004 wt% or more, a robust film can be formed on the surface of the positive electrode during battery operation; when the amount of film-forming additive is 10 wt% or less, side reactions caused by the film-forming additive can be prevented, and the increase in resistance caused by the formation of a thick film on the surface of the positive electrode can be prevented.

[0104] Furthermore, since the descriptions of the positive electrode active material and film-forming additives overlap with the above descriptions, their descriptions will be omitted.

[0105] In addition to the positive electrode active material and film-forming additives, the positive electrode material mixture layer may optionally further include a binder, a conductive agent, and / or a thickener.

[0106] When the cathode material mixture layer contains a binder, the binder content in the cathode material mixture layer can be from 0.1% by weight to 15% by weight, specifically from 0.1% by weight to 10% by weight.

[0107] When a conductive agent is included in the cathode material mixture layer, the content of the conductive agent in the cathode material mixture layer can be from 0.1% by weight to 10.0% by weight, preferably from 0.1% by weight to 8.0% by weight.

[0108] When a thickener is included in the cathode material mixture layer, the content of the thickener in the cathode material mixture layer can be from 0.5% by weight to 5% by weight.

[0109] In addition, since the descriptions of adhesives, conductive agents and thickeners overlap with the above descriptions, their descriptions will be omitted.

[0110] The thickness of the cathode material mixture layer can be from 50 μm to 500 μm, specifically from 100 μm to 300 μm.

[0111] Specifically, the positive electrode of the present invention may include a urea-containing film disposed on a portion or the entire surface of the positive electrode material mixture layer. Specifically, when the compound represented by Formula 1, as a film-forming additive, decomposes during the formation process, a urea-containing film with enhanced lithium-ion properties can be formed on the positive electrode surface through a ring-opening reaction caused by oxidation. In particular, since the urea component contained in the compound represented by Formula 1 can inhibit positive electrode degradation reactions, or can form a robust polymer film to prevent film degradation and ensure high thermal safety of the positive electrode surface, the effects of improved high-temperature lifetime characteristics and resistivity increase rate can be obtained.

[0112] The positive electrode may also include a positive electrode current collector. Specifically, the positive electrode material mixture layer may be disposed on at least one surface of the positive electrode current collector, specifically, on one or two surfaces.

[0113] There are no particular restrictions on the positive electrode current collector, as long as it is conductive and does not cause chemical changes in the battery. It can be made of materials such as stainless steel, aluminum, nickel, titanium, sintered carbon, or aluminum or stainless steel that has been surface-treated with one of carbon, nickel, titanium, silver, etc.

[0114] Furthermore, the thickness of the positive electrode current collector is not particularly limited and can be set within an appropriate range considering the mechanical strength of the positive electrode, productivity, or battery capacity. For example, the thickness of the positive electrode current collector can typically range from 3 μm to 500 μm. Additionally, tiny irregularities can be formed on the surface of the current collector to improve the adhesion of the positive electrode material. The positive electrode current collector can be used in various shapes, such as films, sheets, foils, meshes, porous bodies, foams, nonwoven fabrics, etc.

[0115] The positive electrode of the present invention can be prepared according to known positive electrode preparation methods in the art. For example, the positive electrode of the present invention can be prepared by a positive electrode preparation method including the following steps: preparing a positive electrode slurry composition, then coating the positive electrode slurry composition onto a positive electrode current collector; drying and then rolling the positive electrode slurry composition, thereby forming a positive electrode material mixture layer. Furthermore, the positive electrode of the present invention can be prepared by a positive electrode preparation method including the following steps: casting the positive electrode slurry composition onto a separate support; and laminating a positive electrode material mixture layer film, separate from the support, onto the positive electrode current collector.

[0116] Specifically, the present invention provides a method for preparing a positive electrode for a secondary battery, the method comprising the following steps: The positive electrode slurry composition is coated onto the positive electrode current collector; and The positive electrode slurry composition is dried and rolled to form a positive electrode material mixture layer. The positive electrode slurry composition is the positive electrode slurry composition of the present invention.

[0117] According to this method for preparing a positive electrode for secondary batteries, since a film-forming additive is introduced into the positive electrode slurry composition during the positive electrode material mixture layer formation step, the formation of the positive electrode film can proceed more smoothly compared to introducing the film-forming additive into the positive electrode by adding it to a non-aqueous electrolyte. Therefore, the positive electrode and secondary battery prepared by this method exhibit excellent high-temperature cycle life and high-temperature storage performance.

[0118] The drying temperature can be in the range of 80°C to 250°C.

[0119] Lithium secondary batteries

[0120] The lithium secondary battery of the present invention may include the positive electrode of the present invention, the negative electrode facing the positive electrode, and the electrolyte.

[0121] Furthermore, if necessary, the lithium secondary battery of the present invention may further include a separator disposed between the positive electrode and the negative electrode.

[0122] Since the description of the constituent materials and preparation method of the positive electrode of the present invention overlaps with the above description, their description will be omitted, and other components will be described below.

[0123] (1) Negative electrode

[0124] The negative electrode used in the lithium secondary battery of the present invention may include a negative electrode material mixture layer, which includes a negative electrode active material and a conductive agent.

[0125] The negative electrode active material may include at least one selected from the following: lithium metal, carbon material capable of reversibly inserting / de-inserting lithium ions, metal or lithium-metal alloy, metal composite oxide, material that can be doped or de-doped with lithium, and transition metal oxide.

[0126] As carbon materials capable of reversibly inserting / deintercalating lithium ions, carbon-based anode active materials commonly used in lithium-ion secondary batteries can be used without particular limitations, and crystalline carbon and / or amorphous carbon can be used as typical examples. Examples of crystalline carbon can be graphite, such as irregular, planar, flake, spherical, or fibrous natural or artificial graphite, and examples of amorphous carbon can be soft carbon (low-temperature sintered carbon) or hard carbon, mesophase pitch carbides, and calcined coke.

[0127] As the metal or an alloy of lithium and a metal, a metal selected from the group consisting of copper (Cu), nickel (Ni), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), silicon (Si), antimony (Sb), lead (Pb), indium (In), zinc (Zn), barium (Ba), radium (Ra), germanium (Ge), aluminum (Al) and tin (Sn), or an alloy of lithium and said metal may be used.

[0128] As the metal composite oxide, a substance selected from the group consisting of PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5, Li x Fe2O3 (0≤x≤1), Li x WO2(0≤x≤1) and Sn x Me 1-x Me' y O z (Me: Mn, Fe, Pb or Ge; Me': Al, boron (B), phosphorus (P), Si, elements of Groups I, II and III of the periodic table or halogen; 0<x≤1; 1≤y≤3; 1≤z≤8) may be used.

[0129] Materials capable of doping and dedoping lithium may include Si, SiO x (0<x<2), Si-Y alloys (wherein Y is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements and combinations thereof, and is not Si), Sn, SnO2 or Sn-Y (wherein Y is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements and combinations thereof, and is not Sn), and a mixture of SiO2 and at least one of the foregoing may also be used. The element Y may be selected from the group consisting of Mg, Ca, Sr, Ba, Ra, scandium (Sc), yttrium (Y), Ti, zirconium (Zr), hafnium (Hf), Rf, V, niobium (Nb), Ta, Db, Cr, Mo, tungsten (W), Sg, technetium (Tc), rhenium (Re), Bh, Fe, Pb, ruthenium (Ru), osmium (Os), Hs, rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt), Cu, silver (Ag), gold (Au), Zn, cadmium (Cd), B, Al, gallium (Ga), Sn, In, Ge, P, arsenic (As), Sb, bismuth (Bi), sulfur (S), selenium (Se), tellurium (Te), polonium (Po) and combinations thereof.

[0130] Transition metal oxides may include lithium-containing titanium composite oxides (LTO), vanadium oxides and lithium vanadium oxides.

[0131] According to one embodiment, the negative electrode active material can be used by including a carbon-based negative electrode active material or by including a silicon-based negative electrode active material and a carbon-based negative electrode active material.

[0132] Based on the total weight of the anode material mixture layer, the content of the anode active material can be from 80% to 98% by weight. When the amount of anode active material meets the above range, excellent capacity characteristics and electrochemical properties can be obtained.

[0133] A conductive agent is used to provide conductivity to the electrode. Any conductive agent can be used without particular limitation, as long as it has suitable electronic conductivity and does not cause adverse chemical changes in the battery. The conductive agent can be the same as or different from the conductive agent included in the positive electrode.

[0134] As conductive agents, the following can be used: carbon black, such as acetylene black (or Denka black), Ketjen black, channel black, furnace black, lamp black, or thermally cracked carbon black; graphite powder, such as natural graphite, artificial graphite, or graphite with a well-developed crystal structure; conductive fibers, such as carbon fibers or metal fibers; conductive powders, such as fluorocarbon powders, aluminum powder, and nickel powder; conductive whiskers, such as zinc oxide whiskers and potassium titanate whiskers; conductive metal oxides, such as titanium oxide; or polyphenylene derivatives, and any one or a mixture of two or more of them can be used.

[0135] Based on the total weight of the negative electrode material mixture layer, the content of the conductive agent in the negative electrode material mixture layer can be from about 0.01 wt% to 2.0 wt%, particularly from 0.01 wt% to 1.5 wt%, and more particularly from 0.01 wt% to 1.0 wt%. When the amount of conductive agent is 0.01 wt% or more, the conductivity between the active materials can be sufficiently ensured, and when the amount of conductive agent is 2.0 wt% or less, a high-capacity lithium secondary battery that ensures excellent performance can be prepared by increasing the amount of negative electrode active material contained in the negative electrode material mixture layer.

[0136] The negative electrode material mixture layer may further include an adhesive.

[0137] Adhesives are components that facilitate adhesion between conductive agents, active materials, and current collectors. Examples of adhesives include: fluoropolymer adhesives, including polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE); rubber adhesives, including styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, or styrene-isoprene rubber; cellulose adhesives, including carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, or regenerated cellulose; polyol adhesives, including polyvinyl alcohol; polyolefin adhesives, including polyethylene or polypropylene; polyimide adhesives; polyester adhesives; and silane adhesives.

[0138] Based on the total weight of the negative electrode material mixture layer, the content of the binder in the negative electrode material mixture layer can be from 0.1% by weight to 15.0% by weight, preferably from 0.1% by weight to 10.0% by weight.

[0139] The negative electrode may also include a negative electrode current collector. Specifically, a layer of negative electrode material mixture may be disposed on the negative electrode current collector.

[0140] There are no particular limitations on the negative electrode current collector, as long as it has high conductivity and does not cause adverse chemical changes in the battery. Materials used include, for example, copper, stainless steel, aluminum, nickel, titanium, sintered carbon, copper or stainless steel surface-treated with one of carbon, nickel, titanium, or silver, or aluminum-cadmium alloys. Furthermore, the negative electrode current collector typically has a thickness from 3 μm to 500 μm, and similar to the positive electrode current collector, micro-irregularities can be formed on its surface to improve the adhesion of the negative electrode active material. For example, the negative electrode current collector can be used in various shapes, such as films, sheets, foils, meshes, porous bodies, foams, and nonwoven fabrics.

[0141] The negative electrode can be prepared according to negative electrode preparation methods known in the art. For example, the negative electrode can be prepared by dissolving or dispersing a carbon-based active material, a negative electrode conductive agent, and an optional binder in a solvent to prepare a negative electrode slurry, coating the negative electrode slurry onto a negative electrode current collector, rolling and drying the coated negative electrode current collector to form a negative electrode material mixture layer; or it can be prepared by casting the negative electrode slurry onto a support, and then laminating a negative electrode material mixture layer film separated from the support onto the negative electrode current collector.

[0142] The solvent can be any solvent commonly used in the art, and can include dimethyl sulfoxide (DMSO), isopropanol, N-methylpyrrolidone (NMP), acetone, or water, and mixtures of any one or more of them can be used. Considering the coating thickness, manufacturing yield, and processability of the negative electrode material mixture, the amount of solvent used can be sufficient and is not particularly limited if the negative electrode slurry can be adjusted to have an appropriate viscosity.

[0143] (2) Electrolytes

[0144] The electrolyte included in the lithium secondary battery of the present invention can be a gel electrolyte, a solid electrolyte, or a non-aqueous electrolyte. Specifically, the non-aqueous electrolyte may include lithium salts, non-aqueous organic solvents, and additives.

[0145] (2-1) Lithium salts

[0146] First, any lithium salt commonly used in lithium secondary battery electrolytes can be used as the lithium salt without limitation; for example, the lithium salt may include Li. +As a cation, it may include F-selected from - Cl - ,Br - I - NO3 - N(CN)2 - BF4 - ClO4 - B 10 Cl 10 - AlCl4 - AlO2 - PF6 - CF3SO3 - CH3CO2 - CF3CO2 - AsF6 - SbF6 - CH3SO3 - (CF3CF2SO2)2N - (CF3SO2)2N - (FSO2)2N - BF2C2O4 - BC4O8 - PF4C2O4 - PF2C4O8 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - C4F9SO3 - CF3CF2SO3 - CF3CF2(CF3)2CO - (CF3SO2)2CH - Or CF3(CF2)7SO3 - At least one of them is used as an anion.

[0147] Specifically, lithium salts may include a single material selected from the following or a mixture of two or more of them: LiCl, LiBr, LiI, LiBF4, LiClO4, LiB 10 Cl 10The following are also included: LiAlCl4, LiAlO2, LiPF6, LiCF3SO3, LiCH3CO2, LiCF3CO2, LiAsF6, LiSbF6, LiCH3SO3, LiN(SO2F)2 (lithium bis(fluorosulfonyl)imide, LiFSi), LiN(SO2CF2CF3)2 (lithium bis(perfluoroethanesulfonyl)imide, LiBETI), or LiN(SO2CF3)2 (lithium bis(trifluoromethanesulfonyl)imide, LiTFSI), and may specifically include at least one selected from LiBF4, LiPF6, LiN(SO2F)2 (lithium bis(fluorosulfonyl)imide, LiFSi), LiN(SO2CF2CF3)2 (lithium bis(perfluoroethanesulfonyl)imide, LiBETI), or LiN(SO2CF3)2 (lithium bis(trifluoromethanesulfonyl)imide, LiTFSI). In addition to the lithium salts mentioned above, lithium salts commonly used in lithium secondary battery electrolytes can be used without restriction.

[0148] The lithium salt can be appropriately varied within the generally available range, but it can be included in the electrolyte at a concentration of 0.8 M to 3.0 M, specifically 1.0 M to 2.0 M, preferably 1.0 M to 1.8 M, to obtain the best effect on the formation of an anti-corrosion film on the electrode surface.

[0149] When the lithium salt concentration is within the above range, the viscosity of the non-aqueous electrolyte can be controlled to achieve optimal impregnation and the lithium ion mobility can be improved to enhance the capacity and cycle characteristics of the lithium secondary battery.

[0150] (2-2) Non-aqueous organic solvents

[0151] In addition, non-aqueous organic solvents are described below.

[0152] Various organic solvents commonly used in non-aqueous electrolytes can be used as non-aqueous organic solvents without limitation, wherein there is no restriction on the type of solvent, as long as it can minimize the decomposition caused by oxidation reaction during the charging and discharging process of the secondary battery and can exhibit the desired performance together with the additive.

[0153] Specifically, the non-aqueous organic solvent may include at least one of cyclic carbonate organic solvents and linear carbonate organic solvents to ensure high ionic conductivity.

[0154] Cyclic carbonate organic solvents are high-viscosity organic solvents that allow for the good dissociation of lithium salts in non-aqueous electrolytes due to their high dielectric constant. Specific examples of cyclic carbonate organic solvents may be at least one organic solvent selected from ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentene carbonate, 2,3-pentene carbonate, or vinylene carbonate, or cyclic carbonate organic solvents may include at least one of ethylene carbonate (EC) and propylene carbonate (PC).

[0155] Linear carbonate organic solvents are organic solvents with low viscosity and low dielectric constant. As a specific example, linear carbonate organic solvents may include at least one selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate, or ethyl propyl carbonate, and linear carbonate organic solvents may specifically include at least one selected from dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate.

[0156] In this invention, to ensure high ionic conductivity, cyclic carbonate compounds and linear carbonate compounds can be mixed and used as a non-aqueous organic solvent. In this case, cyclic carbonate compounds and linear carbonate compounds can be mixed and used in volume ratios of 10:90 to 50:50, 10:90 to 40:60, or 20:80 to 40:60.

[0157] If desired, non-aqueous organic solvents may additionally include linear ester organic solvents, which have lower melting points and higher stability at high temperatures than cyclic carbonate organic solvents.

[0158] As a specific example, straight-chain ester organic solvents may include at least one organic solvent selected from methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate or butyl propionate, and preferably at least one of ethyl propionate and propyl propionate.

[0159] Unless otherwise stated, the remaining portion of the non-aqueous electrolyte of the present invention, excluding lithium salts and additives, may consist entirely of non-aqueous organic solvents.

[0160] (2-3) Additives

[0161] Next, the non-aqueous electrolyte of the present invention may include additives to prevent negative electrode collapse caused by the decomposition of the non-aqueous electrolyte in a high-power environment, and at the same time improve the low-temperature high-rate discharge characteristics, high-temperature stability, overcharge protection, and the effect of suppressing battery swelling at high temperatures by forming a robust film on the negative electrode surface.

[0162] As a specific example, the additive may further include at least one selected from cyclic carbonates, fluorinated cyclic carbonates, sulopentalides, sulfates / esters, phosphates / esters, nitriles, benzenes, amines, or silanes.

[0163] Cyclic carbonate compounds may include vinylene carbonate (VC) or vinyl ethylene carbonate. Based on the total weight of the non-aqueous electrolyte, the content of cyclic carbonate compounds can be from 1.0 wt% to 10 wt%, specifically from 1.0 wt% to 5.0 wt%. When the amount of cyclic carbonate compounds meets the above range, the low-temperature output, high-temperature storage characteristics, and high-temperature life characteristics of the battery can be effectively improved while suppressing side reactions.

[0164] Furthermore, fluorinated cyclic carbonate compounds may include fluoroethylene carbonate (FEC). Since fluoroethylene carbonate (FEC) minimizes damage to the solid electrolyte interphase (SEI) membrane during high-voltage charge-discharge by forming a robust film containing polymer components on the negative electrode surface, it can prevent negative electrode degradation. Based on the total amount of lithium difluorophosphate (LiDFP) and hexamethylene diisocyanate, fluorinated cyclic carbonate compounds may be included in an amount of 500 to 1000 parts by weight. When the amount of fluorinated cyclic carbonate compounds meets the above range, by forming a robust film on the surfaces of the positive and negative electrodes, degradation of the positive and negative electrodes during high-voltage charging and high-temperature storage can be effectively prevented, while side reactions due to undecomposed additive residues are also prevented.

[0165] Furthermore, the sulfonyl compounds may include at least one compound selected from 1,3-propanesulfonyl (PS), 1,4-butanesulfonyl, vinylsulfonyl, 1,3-propenesulfonyl (PRS), 1,4-butenesulfonyl, or 1-methyl-1,3-propenesulfonyl, and preferably include 1,3-propanesulfonyl (PS). Since the sulfonyl compounds prevent side reactions between the negative electrode and the electrolyte at high temperatures by forming a stable SEI film on the negative electrode surface through a reduction reaction, they can suppress gas generation and achieve increased durability during high-temperature storage. Based on the total weight of the non-aqueous electrolyte, the content of the sulfonyl compounds can be from 1.0 wt% to 10 wt%, specifically from 1.0 wt% to 5.0 wt%. When the amount of sulfonyl compounds meets the above range, by forming a robust film on the surfaces of the positive and negative electrodes, the degradation of the positive and negative electrodes during high-voltage charging and high-temperature storage can be effectively prevented.

[0166] Furthermore, the sulfate / ester compounds may include ethylene sulfate (Esa), trimethylene sulfate (TMS), or methyltrimethylamine sulfate (MTMS). Based on the total weight of the non-aqueous electrolyte, the content of the sulfate / ester compounds can be from 0.01% by weight to 10% by weight, specifically from 0.05% by weight to 5.0% by weight. If the amount of sulfate / ester compounds meets the above range, it can achieve excellent improvement in lifespan characteristics by suppressing side reactions in the electrolyte during battery charging and discharging and forming a robust SEI film.

[0167] The phosphate / ester compounds may include at least one compound selected from lithium difluoro(dioxa)phosphate, lithium difluorophosphate (LiDFP), tris(trimethylsilyl)phosphate, tris(2,2,2-trifluoroethyl)phosphate, or tris(trifluoroethyl)phosphate. Based on the total weight of the non-aqueous electrolyte, the content of the phosphate / ester compounds may be from 0.01% by weight to 10% by weight, specifically from 0.05% by weight to 5.0% by weight. When the amount of phosphate / ester compounds meets the above range, the formation of a robust SEI film can improve the battery's low-temperature output, high-temperature storage characteristics, and high-temperature lifespan.

[0168] In addition, nitrile compounds may include at least one compound selected from butadionitrile, hexanetrionitrile (HTCN), adiponitrile, acetonitrile, propionitrile, butadionitrile, valerate, octanoic acid, heptanonitrile, hexamethylene diisocyanate, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, or 4-fluorophenylacetonitrile.

[0169] Based on the total weight of the non-aqueous electrolyte, the content of nitrile compounds can be from 1.0 wt% to 10 wt%, specifically from 1.0 wt% to 5.0 wt%. When the amount of nitrile compounds meets the above range, it can suppress the generation of gas caused by side reactions between the positive electrode and the electrolyte, and can effectively suppress the dissolution of metallic foreign matter by forming a stable film on the surface of the negative electrode and the positive electrode.

[0170] Benzene compounds may include fluorobenzene. Based on the total weight of the non-aqueous electrolyte, the content of benzene compounds may be from 0.01% by weight to 10% by weight, specifically from 0.05% by weight to 5.0% by weight.

[0171] The amine compounds may include triethanolamine or ethylenediamine. Based on the total weight of the non-aqueous electrolyte, the content of the amine compounds may be from 0.01% by weight to 10% by weight, specifically from 0.05% by weight to 5.0% by weight.

[0172] Silane compounds may include tetravinylsilane. Based on the total weight of the non-aqueous electrolyte, the content of silane compounds may be from 0.01% by weight to 10% by weight, specifically from 0.05% by weight to 5.0% by weight.

[0173] (3) Diaphragm

[0174] The separator separates the negative and positive electrodes and provides a path for the movement of lithium ions. Any separator can be used without particular limitation, as long as it is commonly used in lithium secondary batteries. In particular, separators with high electrolyte retention capacity and low resistance to electrolyte ion transport can be used.

[0175] Specifically, as the diaphragm, porous polymer membranes can be used, such as porous polymer membranes made of polyolefin polymers (e.g., ethylene homopolymers, propylene homopolymers, ethylene / butene copolymers, ethylene / hexene copolymers, and ethylene / methacrylate copolymers), or laminated structures having two or more layers can be used. Furthermore, common porous nonwoven fabrics can be used, such as nonwoven fabrics formed from high-melting-point glass fibers or polyethylene terephthalate fibers. In addition, coated diaphragms comprising ceramic components or polymer materials can be used to ensure heat resistance or mechanical strength, and diaphragms with single-layer or multi-layer structures can be optionally used.

[0176] The lithium secondary battery of the present invention, as described above, is suitable for use in portable devices (e.g., mobile phones, laptops, and digital cameras) and electric vehicles (e.g., hybrid electric vehicles (HEVs)).

[0177] The shape of the lithium secondary battery of the present invention is not particularly limited, and it can be cylindrical, prismatic, pouch-shaped or coin-shaped.

[0178] The lithium secondary battery of the present invention can be used not only as a single cell for use as a power source for small devices, but also preferably as a unit cell in a medium or large battery module comprising multiple single cells.

[0179] The invention will now be described in more detail with reference to embodiments. However, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these exemplary embodiments are provided so that this description will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0180] [Example]

[0181] Example 1

[0182] (Preparation of the positive electrode slurry composition)

[0183] The positive electrode active material (Li(Ni) 0.6 Mn 0.3 Co 0.1 O2), conductive agent (carbon nanotubes), binder (PVDF) and thickener (CMC) were dissolved in N-methylpyrrolidone (NMP) in a weight ratio of 97.00:1.20:1.44:0.36. Then, a compound represented by Formula 1A was added as a film-forming additive, such that the amount of the compound represented by Formula 1A was 0.4% by weight based on the total solids content, to prepare a positive electrode slurry composition.

[0184] (Preparation of the positive electrode)

[0185] The positive electrode slurry composition prepared above was coated onto a 12 μm thick aluminum (Al) foil current collector, dried at 50°C for 2 hours, and pressed to prepare a positive electrode on which a layer of positive electrode material mixture was formed.

[0186] (Preparation of the negative electrode)

[0187] The negative electrode active material (graphite and SiC = 95:5 by weight), binder (SBR), and bundled single-walled carbon nanotubes (SWCNTs) with an average diameter of 10 nm and a length of 7 μm and a specific surface area of ​​1000 m² were used as conductive agents. 2 A negative electrode active material slurry was prepared by adding (g, manufacturer: ANP) to distilled water at a weight ratio of 96.84:3.15:0.01. The prepared negative electrode active material slurry was coated onto a 15 μm thick copper current collector, dried, and then rolled to prepare the negative electrode.

[0188] (Preparation of non-aqueous electrolytes)

[0189] LiPF6 was dissolved in a non-aqueous solvent (in which ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 2:7:1) to make the concentration of LiPF6 1.2 M, and then 0.5% by weight of ethylene carbonate was added to prepare a non-aqueous electrolyte.

[0190] (Preparation of secondary batteries)

[0191] A porous membrane (polypropylene) is placed between the positive electrode and the negative electrode facing the positive electrode to prepare an electrode assembly. Then, the electrode assembly is housed in a battery case and injected with the non-aqueous electrolyte prepared above to prepare a lithium secondary battery.

[0192] Example 2

[0193] (Preparation of the positive electrode slurry composition)

[0194] The positive electrode slurry composition was prepared in the same manner as in Example 1, except that the compound represented by Formula 1B was used instead of the compound represented by Formula 1A as a film-forming additive.

[0195] (Preparation of the positive electrode)

[0196] The positive electrode slurry composition prepared above was coated onto a 12 μm thick aluminum (Al) foil current collector, dried at 50°C for 2 hours, and pressed to prepare a positive electrode on which a layer of positive electrode material mixture was formed.

[0197] (Preparation of secondary batteries)

[0198] A lithium secondary battery was prepared in the same manner as in Example 1, except that it included the positive electrode prepared above.

[0199] Example 3

[0200] (Preparation of the positive electrode slurry composition)

[0201] The positive electrode slurry composition was prepared in the same manner as in Example 1, except that the compound represented by Formula 1C was used instead of the compound represented by Formula 1A as a film-forming additive.

[0202] (Preparation of the positive electrode)

[0203] The positive electrode slurry composition prepared above was coated onto a 12 μm thick aluminum (Al) foil current collector, dried at 50°C for 2 hours, and pressed to prepare a positive electrode on which a layer of positive electrode material mixture was formed.

[0204] (Preparation of secondary batteries)

[0205] A lithium secondary battery was prepared in the same manner as in Example 1, except that it included the positive electrode prepared above.

[0206] Example 4

[0207] (Preparation of the positive electrode slurry composition)

[0208] The positive electrode slurry composition was prepared in the same manner as in Example 1, except that the compound represented by Formula 1D was used instead of the compound represented by Formula 1A as a film-forming additive.

[0209] (Preparation of the positive electrode)

[0210] The positive electrode slurry composition prepared above was coated onto a 12 μm thick aluminum (Al) foil current collector, dried at 50°C for 2 hours, and pressed to prepare a positive electrode on which a layer of positive electrode material mixture was formed.

[0211] (Preparation of secondary batteries)

[0212] A lithium secondary battery was prepared in the same manner as in Example 1, except that it included the positive electrode prepared above.

[0213] Example 5

[0214] (Preparation of the positive electrode slurry composition)

[0215] The positive electrode slurry composition was prepared in the same manner as in Example 1, except that the compound represented by Formula 1E was used instead of the compound represented by Formula 1A as a film-forming additive.

[0216] (Preparation of the positive electrode)

[0217] The positive electrode slurry composition prepared above was coated onto a 12 μm thick aluminum (Al) foil current collector, dried at 50°C for 2 hours, and pressed to prepare a positive electrode on which a layer of positive electrode material mixture was formed.

[0218] (Preparation of secondary batteries)

[0219] A lithium secondary battery was prepared in the same manner as in Example 1, except that it included the positive electrode prepared above.

[0220] Example 6

[0221] (Preparation of the positive electrode slurry composition)

[0222] The positive electrode slurry composition was prepared in the same manner as in Example 1, except that the compound represented by Formula 1F was used instead of the compound represented by Formula 1A as a film-forming additive.

[0223] (Preparation of cathode materials)

[0224] The positive electrode slurry composition prepared above was coated onto a 12 μm thick aluminum (Al) foil current collector, dried at 50°C for 2 hours, and pressed to prepare a positive electrode on which a layer of positive electrode material mixture was formed.

[0225] (Preparation of secondary batteries)

[0226] A lithium secondary battery was prepared in the same manner as in Example 1, except that it included the positive electrode prepared above.

[0227] Example 7

[0228] (Preparation of the positive electrode slurry composition)

[0229] The positive electrode slurry composition was prepared in the same manner as in Example 1, except that the compound represented by Formula 1G was used instead of the compound represented by Formula 1A as a film-forming additive.

[0230] (Preparation of the positive electrode)

[0231] The positive electrode slurry composition prepared above was coated onto a 12 μm thick aluminum (Al) foil current collector, dried at 50°C for 2 hours, and pressed to prepare a positive electrode on which a layer of positive electrode material mixture was formed.

[0232] (Preparation of secondary batteries)

[0233] A lithium secondary battery was prepared in the same manner as in Example 1, except that it included the positive electrode prepared above.

[0234] Example 8

[0235] (Preparation of the positive electrode slurry composition)

[0236] The positive electrode active material (Li(Ni) 0.6 Mn 0.3 Co 0.1 O2), conductive agent (carbon nanotubes), binder (PVDF) and thickener (CMC) were dissolved in N-methylpyrrolidone (NMP) in a weight ratio of 97.00:1.20:1.44:0.36. Then, a compound represented by Formula 1A was added as a film-forming additive, such that the amount of the compound represented by Formula 1A was 10.0% by weight based on the total solids content, to prepare a positive electrode slurry composition.

[0237] (Preparation of the positive electrode)

[0238] The positive electrode slurry composition prepared above was coated onto a 12 μm thick aluminum (Al) foil current collector, dried at 50°C for 2 hours, and pressed to prepare a positive electrode on which a layer of positive electrode material mixture was formed.

[0239] (Preparation of secondary batteries)

[0240] A lithium secondary battery was prepared in the same manner as in Example 1, except that the positive electrode prepared above was used.

[0241] Example 9

[0242] (Preparation of the positive electrode slurry composition)

[0243] The positive electrode active material (Li(Ni) 0.6 Mn 0.3 Co 0.1 O2), conductive agent (carbon nanotubes), binder (PVDF) and thickener (CMC) were dissolved in N-methylpyrrolidone (NMP) in a weight ratio of 97.00:1.20:1.44:0.36. Then, a compound represented by Formula 1A was added as a film-forming additive, such that the amount of the compound represented by Formula 1A was 1.0% by weight based on the total solids content, to prepare a positive electrode slurry composition.

[0244] (Preparation of the positive electrode)

[0245] The positive electrode slurry composition prepared above was coated onto a 12 μm thick aluminum (Al) foil current collector, dried at 50°C for 2 hours, and pressed to prepare a positive electrode on which a layer of positive electrode material mixture was formed.

[0246] (Preparation of secondary batteries)

[0247] A lithium secondary battery was prepared in the same manner as in Example 1, except that the positive electrode prepared above was used.

[0248] Example 10

[0249] (Preparation of the positive electrode slurry composition)

[0250] The positive electrode active material (Li(Ni) 0.6 Mn 0.3 Co 0.1 O2), conductive agent (carbon nanotubes), binder (PVDF) and thickener (CMC) were dissolved in N-methylpyrrolidone (NMP) in a weight ratio of 97.00:1.20:1.44:0.36. Then, a compound represented by Formula 1A was added as a film-forming additive, such that the amount of the compound represented by Formula 1A was 5.0% by weight based on the total solids content, to prepare a positive electrode slurry composition.

[0251] (Preparation of the positive electrode)

[0252] The positive electrode slurry composition prepared above was coated onto a 12 μm thick aluminum (Al) foil current collector, dried at 50°C for 2 hours, and pressed to prepare a positive electrode on which a layer of positive electrode material mixture was formed.

[0253] (Preparation of secondary batteries)

[0254] A lithium secondary battery was prepared in the same manner as in Example 1, except that the positive electrode prepared above was used.

[0255] Example 11

[0256] (Preparation of the positive electrode slurry composition)

[0257] The positive electrode active material (Li(Ni) 0.6 Mn 0.3 Co 0.1 O2), conductive agent (carbon nanotubes), binder (PVDF) and thickener (CMC) were dissolved in N-methylpyrrolidone (NMP) in a weight ratio of 97.00:1.20:1.44:0.36. Then, a compound represented by Formula 1A was added as a film-forming additive, such that the amount of the compound represented by Formula 1A was 8.0% by weight based on the total solids content, to prepare a positive electrode slurry composition.

[0258] (Preparation of the positive electrode)

[0259] The positive electrode slurry composition prepared above was coated onto a 12 μm thick aluminum (Al) foil current collector, dried at 50°C for 2 hours, and pressed to prepare a positive electrode on which a layer of positive electrode material mixture was formed.

[0260] (Preparation of secondary batteries)

[0261] A lithium secondary battery was prepared in the same manner as in Example 1, except that the positive electrode prepared above was used.

[0262] Comparative Example 1

[0263] (Preparation of the positive electrode slurry composition)

[0264] The positive electrode active material (Li(Ni) 0.6 Mn 0.3 Co 0.1 A positive electrode slurry composition was prepared by dissolving O2, conductive agent (carbon nanotubes), binder (PVDF) and thickener (CMC) in N-methylpyrrolidone (NMP) in a weight ratio of 97.00:1.20:1.44:0.36.

[0265] (Preparation of the positive electrode)

[0266] The positive electrode slurry composition prepared above was coated onto a 12 μm thick aluminum (Al) foil current collector, dried at 50°C for 2 hours, and pressed to prepare a positive electrode on which a layer of positive electrode material mixture was formed.

[0267] (Preparation of the negative electrode)

[0268] The negative electrode active material (graphite and SiC = 95:5 by weight), binder (SBR), and bundled single-walled carbon nanotubes (SWCNTs) with an average diameter of 10 nm and a length of 7 μm and a specific surface area of ​​1000 m² were used as conductive agents. 2 A negative electrode active material slurry was prepared by adding (g, manufacturer: ANP) to distilled water at a weight ratio of 96.84:3.15:0.01. The prepared negative electrode active material slurry was coated onto a 15 μm thick copper current collector, dried, and then rolled to prepare the negative electrode.

[0269] (Preparation of non-aqueous electrolytes)

[0270] LiPF6 was dissolved in a non-aqueous solvent (in which ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 2:7:1) to make the concentration of LiPF6 1.2 M, and then 0.5% by weight of ethylene carbonate was added to prepare a non-aqueous electrolyte.

[0271] (Preparation of secondary batteries)

[0272] A porous polypropylene separator is placed between the prepared positive and negative electrodes to prepare an electrode assembly. Then, the electrode assembly is housed in a battery case and injected with the non-aqueous electrolyte prepared above to prepare a lithium secondary battery.

[0273] Comparative Example 2

[0274] (Preparation of non-aqueous electrolytes)

[0275] LiPF6 was dissolved in a non-aqueous solvent (in which ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) were mixed in a volume ratio of 2:7:1) to make the concentration of LiPF6 1.2 M, and then 1.0 wt% of the compound represented by formula 1A and 0.5 wt% of ethylene carbonate were added to prepare a non-aqueous electrolyte.

[0276] (Preparation of secondary batteries)

[0277] A lithium secondary battery was prepared in the same manner as in Comparative Example 1, except that the non-aqueous electrolyte prepared above was injected.

[0278] Comparative Example 3

[0279] (Preparation of the positive electrode slurry composition)

[0280] The positive electrode slurry composition was prepared in the same manner as in Example 1, except that a compound represented by Formula 3A was used instead of a compound represented by Formula 1A as a film-forming additive.

[0281] [Formula 3A]

[0282] (Preparation of the positive electrode)

[0283] The positive electrode slurry composition prepared above was coated onto a 12 μm thick aluminum (Al) foil current collector, dried at 50°C for 2 hours, and pressed to prepare a positive electrode on which a layer of positive electrode material mixture was formed.

[0284] (Preparation of secondary batteries)

[0285] A lithium secondary battery was prepared in the same manner as in Comparative Example 1, except that it included the positive electrode prepared above.

[0286] Comparative Example 4

[0287] (Preparation of the positive electrode slurry composition)

[0288] The positive electrode slurry composition was prepared in the same manner as in Example 1, except that a compound represented by Formula 3B was used instead of a compound represented by Formula 1A as a film-forming additive.

[0289] [Formula 3B]

[0290] (Preparation of the positive electrode)

[0291] The positive electrode slurry composition prepared above was coated onto a 12 μm thick aluminum (Al) foil current collector, dried at 50°C for 2 hours, and pressed to prepare a positive electrode on which a layer of positive electrode material mixture was formed.

[0292] (Preparation of secondary batteries)

[0293] A lithium secondary battery was prepared in the same manner as in Comparative Example 1, except that it included the positive electrode prepared above.

[0294] Comparative Example 5

[0295] (Preparation of the positive electrode slurry composition)

[0296] The positive electrode slurry composition was prepared in the same manner as in Example 1, except that a compound represented by Formula 3C was used instead of a compound represented by Formula 1A as a film-forming additive.

[0297] [Formula 3C]

[0298] (Preparation of the positive electrode)

[0299] The positive electrode slurry composition prepared above was coated onto a 12 μm thick aluminum (Al) foil current collector, dried at 50°C for 2 hours, and pressed to prepare a positive electrode on which a layer of positive electrode material mixture was formed.

[0300] (Preparation of secondary batteries)

[0301] A lithium secondary battery was prepared in the same manner as in Comparative Example 1, except that it included the positive electrode prepared above.

[0302] Comparative Example 6

[0303] (Preparation of the positive electrode slurry composition)

[0304] The positive electrode slurry composition was prepared in the same manner as in Example 1, except that a compound represented by Formula 3D was used instead of a compound represented by Formula 1A as a film-forming additive.

[0305] [3D Style]

[0306] (Preparation of the positive electrode)

[0307] The positive electrode slurry composition prepared above was coated onto a 12 μm thick aluminum (Al) foil current collector, dried at 50°C for 2 hours, and pressed to prepare a positive electrode on which a layer of positive electrode material mixture was formed.

[0308] (Preparation of secondary batteries)

[0309] A lithium secondary battery was prepared in the same manner as in Comparative Example 1, except that it included the positive electrode prepared above.

[0310] Experimental Example

[0311] Experimental Example 1. Evaluation of High-Temperature Cycling Characteristics

[0312] The lithium secondary batteries prepared in Examples 1 to 11 and the lithium secondary batteries prepared in Comparative Examples 1 to 6 were each charged to 4.5 V at a rate of 0.33C under constant current / constant voltage conditions at room temperature (25°C) and discharged at a rate of 0.33C for 10 seconds. After that, the initial capacity was measured using a PNE-0506 charge-discharge apparatus (manufacturer: PNE solution).

[0313] Then, each lithium secondary battery was charged to 4.5 V at a rate of 0.33C under constant current / constant voltage conditions at a high temperature (45°C), and each lithium secondary battery was discharged to 2.5 V at a rate of 0.33C under constant current conditions. This was set as one cycle, and after 200 cycles, the capacity retention rate, resistance increase rate and gas generation were measured. The results are shown in Table 1 below.

[0314] [Table 1]

[0315] Referring to Table 1, it can be confirmed that the capacity retention (%), resistance increase rate and gas generation after high-temperature cycling are significantly improved compared with the lithium secondary batteries of Comparative Examples 1 to 6.

[0316] Experimental Example 2. Evaluation of High-Temperature Storage Characteristics

[0317] The lithium secondary batteries prepared in Examples 1 to 11 and the lithium secondary batteries prepared in Comparative Examples 1 to 6 were each charged to 4.5 V and discharged at a rate of 0.33C for 10 seconds at a constant current / constant voltage at room temperature (25°C). After that, the initial capacity was measured using a PNE-0506 charge-discharge apparatus (manufacturer: PNE Solution).

[0318] Then, after storing each lithium secondary battery at high temperature (60°C) for 8 weeks, a cycle was performed in which each lithium secondary battery was charged to 4.5 V at a rate of 0.33C under constant current / constant voltage conditions and discharged to 2.5 V under a rate of 0.33C under constant current conditions. The capacity retention rate, resistance increase rate and gas generation were then measured, and the results are presented in Table 2 below.

[0319] [Table 2]

[0320] Referring to Table 2, for the lithium secondary batteries prepared in Examples 1 to 11 of the present invention, it can be confirmed that, compared with the lithium secondary batteries of Comparative Examples 1 to 6, the capacity retention rate (%), resistance increase rate and gas generation after high-temperature storage are significantly improved.

[0321] Experimental Example 3. Evaluation of the Hot Box

[0322] The lithium secondary batteries prepared in Examples 1 to 11 and the lithium secondary battery prepared in Comparative Example 1 were each fully charged to 100% State of Charge (SOC). The fully charged individual cells were stored in a case, and the internal temperature of the case was increased from room temperature to 150°C at a rate of 2°C / min. Then, while storing each lithium secondary battery at 150°C for 120 minutes, it was confirmed whether the stored lithium secondary batteries ignited. The results are shown in Table 3 below. In Table 3, a lithium secondary battery igniting is indicated as a failure, and a lithium secondary battery not igniting is indicated as a pass.

[0323] [Table 3]

[0324] Referring to Table 3, it can be seen that the lithium secondary batteries prepared in Examples 1 to 11 of the present invention do not ignite even during high-temperature storage. Conversely, it can be seen that the lithium secondary battery prepared in Comparative Example 1 ignites during high-temperature storage.

Claims

1. A positive electrode slurry composition for lithium secondary batteries, comprising a positive electrode active material, a film-forming additive, and a solvent. in, The film-forming additive is a compound represented by Formula 1: [Formula 1] In Equation 1, R1 is -SO2F, -OSO2N (R a (R) b -SO2R c -OLi or -OR', where R a and R b Each is independently an alkyl group having 1 to 5 carbon atoms, R c It is an unsubstituted or fluorinated alkyl group having 1 to 5 carbon atoms, and R' is an alkyl group having 1 to 10 carbon atoms.

2. The positive electrode slurry composition for lithium secondary batteries as described in claim 1, wherein, In Equation 1, R1 represents -SO2F, -OSO2N (R a (R) b ) or -SO2R c , where R a and R b Each is independently an alkyl group having 1 to 5 carbon atoms, and R c It is an unsubstituted or fluorinated alkyl group having 1 to 5 carbon atoms.

3. The positive electrode slurry composition for lithium secondary batteries as described in claim 1, wherein, In Equation 1, R1 represents -SO2F, -OSO2N (R a (R) b ) or -SO2R c , where R a and R b Each is independently an alkyl group having 1 to 3 carbon atoms, and R c It is an unsubstituted or fluorinated alkyl group having 1 to 3 carbon atoms.

4. The positive electrode slurry composition for lithium secondary batteries as described in claim 1, wherein, The compound represented by Formula 1 is at least one of the compounds represented by Formulas 1A to 1G: [Formula 1A] [Formula 1B] [Formula 1C] [Formula 1D] [Formula 1E] [Formula 1F] [Formula 1G] 。 5. The positive electrode slurry composition for lithium secondary batteries as described in claim 1, wherein, Based on the total weight of the solid components of the cathode slurry composition, the content of the film-forming additive is from 0.004% by weight to 10% by weight.

6. The positive electrode slurry composition for lithium secondary batteries as described in claim 1, wherein, The content of the film-forming additive is from 0.1% to 8.0% by weight, based on the total weight of the solid components of the cathode slurry composition.

7. The positive electrode slurry composition for lithium secondary batteries as described in claim 1, wherein, The positive electrode active material comprises a compound represented by Formula 2: [Equation 2] Li 1+a Ni x Co y M 1 z M 2 w O2 In Equation 2, M 1 It is manganese (Mn), aluminum (Al), or a combination thereof. M 2 is at least one selected from the group consisting of Al, zirconium (Zr), tungsten (W), titanium (Ti), magnesium (Mg), calcium (Ca) and strontium (Sr), wherein 0≤a≤0.5, 0<x<1.0, 0<y≤0.4, 0<z≤0.4, 0≤w≤0.1, and x+y+z+w=1.

8. The positive electrode slurry composition for lithium secondary batteries as claimed in claim 1, further comprising at least one of a conductive agent, a binder, and a thickener.

9. A positive electrode for a lithium secondary battery, the positive electrode comprising a positive electrode material mixture layer, the positive electrode material mixture layer comprising a positive electrode active material and a film-forming additive, wherein, The film-forming additive is a compound represented by Formula 1: [Formula 1] In Equation 1, R1 is -SO2F, -OSO2N (R a (R) b -SO2R c -OLi or -OR', where R a and R b Each is independently an alkyl group having 1 to 5 carbon atoms, R c It is an unsubstituted or fluorinated alkyl group having 1 to 5 carbon atoms, and R' is an alkyl group having 1 to 10 carbon atoms.

10. The positive electrode for a lithium secondary battery as described in claim 9, wherein, The cathode material mixture layer includes a urea-containing membrane.

11. A method for preparing a positive electrode for a secondary battery, the method comprising: The positive electrode slurry composition is applied to the positive electrode current collector; and A layer of cathode material mixture is formed by drying and rolling the cathode slurry composition. The positive electrode slurry composition is the positive electrode slurry composition for lithium secondary batteries as described in claim 1.

12. A lithium secondary battery, comprising: The positive electrode as claimed in claim 9; the negative electrode facing the positive electrode; and the electrolyte.

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