Non-aqueous electrolyte and lithium secondary battery comprising same

Abstract

The present invention provides a non-aqueous electrolyte comprising a lithium salt, an organic solvent, and an additive, wherein the additive includes a first compound, a second compound, and a third compound. Accordingly, it is possible to provide a lithium secondary battery having excellent cycle characteristics and high-temperature durability by implementing an electrode film having excellent durability and flexibility.

Description

Non-aqueous electrolyte and lithium secondary battery containing the same

[0001] Cross-citation with related applications

[0002] The present application claims the benefit of priority based on Korean Patent Application No. 10-2024-0197790 filed on December 26, 2024 and Korean Patent Application No. 10-2025-0210129 filed on December 24, 2025, and all contents disclosed in said Korean patent application documents are incorporated herein as part of the specification.

[0003] Technology field

[0004] The present invention relates to a non-aqueous electrolyte and a lithium secondary battery containing the same.

[0005]

[0006] Lithium secondary batteries are used in a wide range of fields, including small products such as digital cameras, P-DVDs, MP3 players, 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 for storing surplus power or renewable energy and backup power storage devices.

[0007] Such lithium secondary batteries are generally manufactured by injecting or impregnating a non-aqueous electrolyte into an electrode assembly consisting of a positive electrode, a negative electrode, and a separator, and said positive and negative electrodes include an active material capable of lithium ion intercalation and deintercalation.

[0008] Carbon-based active materials such as graphite have been used as negative electrode active materials for lithium secondary batteries, and recently, the use of silicon-based active materials, which have a higher capacity than carbon-based active materials, is being considered.

[0009] However, while the aforementioned silicon-based active material possesses high capacity, it presents a significant problem due to volume expansion and contraction during the charging and discharging process of lithium secondary batteries. This volume expansion and contraction of the silicon-based active material significantly reduces the conductivity of the negative electrode and causes a decrease in high-temperature durability due to degradation. Furthermore, an electrode film is formed on the electrode surface during initial activation; however, since the silicon-based active material exhibits a large degree of volume expansion, the electrode film cracks. Consequently, the electrode film formation reaction continues, leading to electrolyte depletion and an increase in resistance as the electrode film becomes thicker.

[0010] Therefore, there is a need for technology that can improve the performance of secondary batteries using silicon-based active materials.

[0011]

[0012] The present invention is intended to solve the above-mentioned problems, and by applying an additive comprising a first compound, a second compound, and a third compound to a non-aqueous electrolyte, a SEI film with improved durability can be formed.

[0013] In addition, the present invention can provide a lithium secondary battery with excellent cycle performance and high-temperature performance by including the above-mentioned non-aqueous electrolyte.

[0014]

[0015] [1] The present invention provides a non-aqueous electrolyte comprising a lithium salt, an organic solvent and an additive, wherein the additive comprises a first compound represented by the following chemical formula 1, a second compound represented by the following chemical formula 2, and a third compound represented by the following chemical formula 3.

[0016] [Chemical Formula 1]

[0017]

[0018] [Chemical Formula 2]

[0019]

[0020] [Chemical Formula 3]

[0021]

[0022] In the above Chemical Formulas 1 and 2, R 11 , R 12 , R 13 , R 14 , R 15 , R 21 , R 22 , R 23 , R 24 and R 25 is independently hydrogen or an alkyl group having 1 to 10 carbon atoms, and L1 and L2 are independently a directly bonded ether group (*-O-*), an ester group (*-C(=O)O-*), an alkylene group having 1 to 5 carbon atoms, or a combination thereof, and in the above formula 3, R 31 - and R 32 is an alkyl group having 1 to 10 carbon atoms, with one or more fluorine atoms independently substituted.

[0023] [2] The present invention is, in [1] above, R of the formula 1 above 11 This can provide a non-aqueous electrolyte that is an alkyl group having 1 to 5 carbon atoms.

[0024] [3] The present invention is, in [1] and / or [2], R of Formula 3 31 - and R 32 A non-aqueous electrolyte can be provided, which is an alkyl group having 1 to 5 carbon atoms, with one or more fluorine atoms independently substituted.

[0025] [4] The present invention may provide a non-aqueous electrolyte comprising, in at least one of [1] to [3], one or more compounds selected from the group consisting of compounds represented by the following chemical formulas 1-1 and 1-2.

[0026] [Chemical Formula 1-1]

[0027]

[0028] [Chemical Formula 1-2]

[0029]

[0030] [5] The present invention may provide a non-aqueous electrolyte comprising, in at least one of [1] to [4], one or more compounds selected from the group consisting of compounds represented by the following formulas 2-1 and 2-2.

[0031] [Chemical Formula 2-1]

[0032]

[0033] [Chemical Formula 2-2]

[0034]

[0035] [6] The present invention provides a non-aqueous electrolyte comprising, in at least one of [1] to [5], one or more compounds selected from the group consisting of compounds represented by the following formulas 3-1 and 3-2.

[0036] [Chemical Formula 3-1]

[0037]

[0038] [Chemical Formula 3-2]

[0039]

[0040] [7] The present invention may provide a non-aqueous electrolyte in which, in at least one of [1] to [6], the first compound is included in the non-aqueous electrolyte in an amount of 0.1% to 4% by weight.

[0041] [8] The present invention may provide a non-aqueous electrolyte in which, in at least one of [1] to [7], the second compound is included in the non-aqueous electrolyte in an amount of 0.1% to 4% by weight.

[0042] [9] The present invention may provide a non-aqueous electrolyte in which, in at least one of [1] to [8], the third compound is included in the non-aqueous electrolyte in an amount of 0.1% to 4% by weight.

[0043]

[0010] The present invention may provide a non-aqueous electrolyte comprising at least one organic solvent selected from the group consisting of linear carbonate compounds and cyclic carbonate compounds, in at least one of [1] to [9].

[0044]

[0011] The present invention provides a lithium secondary battery comprising: a positive electrode; a negative electrode facing the positive electrode; a separator interposed between the positive electrode and the negative electrode; and a non-aqueous electrolyte according to at least one of [1] to

[0010] .

[0045]

[0012] The present invention can provide a lithium secondary battery according to

[0011] , wherein the negative electrode comprises a negative electrode active material, and the negative electrode active material comprises at least one selected from the group consisting of a carbon-based active material and a silicon-based active material.

[0046]

[0013] The present invention, in

[0012] above, wherein the silicon-based active material is silicon (Si) and silicon oxide (SiO₂). x , 0 <x<2) 및 실리콘-탄소 복합체(Si / C composite)로 이루어진 군에서 선택된 적어도 1종을 포함하는 리튬 이차전지를 제공할 수 있다.

[0047]

[0014] The present invention can provide a lithium secondary battery in which the silicon-based active material comprises a silicon-carbon composite, in accordance with

[0012] .

[0048]

[0049] The present invention enables the realization of an SEI film with improved durability by applying an additive comprising a first compound capable of forming an organic film, a second compound capable of promoting a ring-opening reaction of the first compound, and a third compound capable of forming an inorganic film to a non-aqueous electrolyte.

[0050] In addition, the present invention can improve cycle performance and high-temperature durability by applying the above-mentioned non-aqueous electrolyte to a lithium secondary battery.

[0051]

[0052] 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.

[0053] 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.

[0054] 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.

[0055] In this specification, terms such as "first" and "second" may be used simply to distinguish one component from another and do not limit the components in other aspects (e.g., importance or stacking order).

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

[0057] In this specification, “*” refers to a bonding site in a chemical formula unless otherwise defined.

[0058] In this specification, "single particle type" refers to a particle formed by the aggregation of 30 or fewer sub-particles. The sub-particle unit constituting the single particle type is referred to as a nodule. The single particle type includes a single particle consisting of one nodule and a pseudo-single particle which is a composite of 2 to 30 nodules.

[0059] In this specification, the “nodule” is a sub-particle unit constituting a single particle and a pseudo-single particle, and may be a single crystal that does not have crystalline grain boundaries, or a polycrystalline material that does not appear to have grain boundaries when observed at a field of view of 5,000 to 20,000 times using a scanning electron microscope.

[0060] In this specification, "secondary particle" refers to a particle formed by the aggregation of more than 30 sub-particles. To distinguish it from the sub-particles constituting a single-particle type particle, the sub-particles constituting the secondary particle are referred to as "primary particles."

[0061] In this specification, “particle” is a concept including any one or all of a single particle, a pseudo-single particle, a primary particle, a nodule, and a secondary particle.

[0062] In this specification, “D min ”, “D 50 ” and “D max ” is a particle size value based on the volume-based particle size distribution of the powder to be measured using the laser diffraction method. Specifically, the above D 50 ☐ may refer to the particle size at the point where the cumulative volume ratio reaches 50% in the volumetric cumulative particle size distribution of the powder under measurement. D min and D maxrepresents the minimum and maximum particle sizes observed, respectively, in the volume-based particle size distribution detectable by the laser diffraction particle size measuring device. The particle size value of the volume-cumulative particle size distribution can be measured, for example, by dispersing the powder to be measured in a dispersion medium, introducing it into a commercially available laser diffraction particle size measuring device (e.g., Microtic MT 3000), irradiating it with ultrasound of about 28 kHz at an output of 60 W, and obtaining a volume-cumulative particle size distribution graph.

[0063] In this specification, “BET specific surface area” is measured by the BET method and can be calculated from the amount of nitrogen gas adsorbed at liquid nitrogen temperature (77K) using, for example, BEL Japan’s BELSORP-mino II.

[0064]

[0065] The present invention will be described in detail below.

[0066] The non-aqueous electrolyte 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.

[0067]

[0068] Non-aqueous electrolytes

[0069] The present invention relates to a non-aqueous electrolyte, specifically a non-aqueous electrolyte for a lithium secondary battery.

[0070] The non-aqueous electrolyte according to the present invention comprises a lithium salt, an organic solvent, and an additive, and by including the additive in the first compound, the second compound, and the third compound, a SEI film with excellent durability can be realized.

[0071] Electrode films formed by conventional non-aqueous electrolytes have a problem in that they crack during repeated charging / discharging or high-temperature storage of lithium secondary batteries, thereby causing degradation of the lithium secondary battery. For example, when a lithium secondary battery contains a silicon-based active material that has a higher capacity than graphite, the film is damaged due to the volume expansion / contraction of the silicon-based active material. Consequently, the continuous decomposition of the solvent contained in the non-aqueous electrolyte leads to a decrease in the ionic conductivity of the electrolyte, thereby accelerating the degradation of the lithium secondary battery.

[0072] Accordingly, the present invention can form an electrode film with excellent durability and thermal stability by applying an additive comprising a first compound capable of forming a flexible organic film, a second compound that promotes ring opening of the first compound, and a third compound capable of forming an inorganic film with excellent mechanical durability to a non-aqueous electrolyte. As a result, the present invention can realize a lithium secondary battery with excellent cycle characteristics and high-temperature durability.

[0073]

[0074] (1) Additive

[0075] The additive according to the present invention comprises a first compound represented by the following chemical formula 1, a second compound represented by the following chemical formula 2, and a third compound represented by the following chemical formula 3.

[0076] [Chemical Formula 1]

[0077]

[0078] [Chemical Formula 2]

[0079]

[0080] [Chemical Formula 3]

[0081]

[0082] In the above Chemical Formulas 1 and 2, R 11 , R 12 , R 13, R 14 , R 15 , R 21 , R 22 , R 23 , R 24 and R 25 is independently hydrogen or an alkyl group having 1 to 10 carbon atoms, and L1 and L2 are independently a directly bonded ether group (*-O-*), an ester group (*-C(=O)O-*), an alkylene group having 1 to 5 carbon atoms, or a combination thereof, and in the above formula 3, R 31 - and R 32 is an alkyl group having 1 to 10 carbon atoms, with one or more fluorine atoms independently substituted.

[0083] The first compound represented by Chemical Formula 1 above can form a polymeric film by causing the hexagonal ring to open and the propargyl group to contribute to extending the chain length during activation or charging and discharging of a lithium secondary battery. A polymeric film having a long chain structure can improve the flexibility and recovery of the electrode film, and, for example, can prevent damage to the electrode film by allowing the structure of the electrode film to deform without damage due to volume expansion of the silicon-based active material. However, when the first compound is used alone, there is a problem in that it is difficult to form the desired electrode film because ring opening is not easily achieved due to steric hindrance or reduced reactivity of the first compound itself.

[0084] Accordingly, the present invention combines the first compound and the second compound capable of promoting the ring-opening reaction of the first compound. Specifically, the second compound represented by Chemical Formula 2 is a coumarin-based compound capable of forming radicals, which promotes the ring-opening of the first compound, thereby enabling the rapid formation of an organic film with excellent flexibility and recovery properties.

[0085] Meanwhile, even when the first compound and the second compound are used in combination, it is necessary to improve mechanical durability along with flexibility to prevent damage such as cracking caused by the expansion of the electrode film. Accordingly, the non-aqueous electrolyte according to the present invention is characterized by using a third compound represented by Chemical Formula 3 together with the first compound and the second compound. The third compound contains a large amount of fluorine to form LiF, which acts as a linker in the film to improve physical durability. That is, the third compound can improve the mechanical durability of the electrode film by forming a LiF-based inorganic film.

[0086] Accordingly, the present invention can realize an electrode film with excellent flexibility and durability by using the first compound, the second compound, and the third compound in combination. Specifically, during the initial activation step of a lithium secondary battery, radicals are formed from the second compound, and said radicals promote the ring-opening reaction of the first compound to form a flexible organic film, and said third compound can form an inorganic film with excellent mechanical durability. As a result, the present invention can provide a non-aqueous electrolyte capable of forming a film with excellent coverage, durability, and thermal stability.

[0087] According to the present invention, R of the above chemical formula 1 11 ≠ may be an alkyl group having 1 to 5 carbon atoms, specifically an alkyl group having 1 to 3 carbon atoms, more specifically a methyl group. The above R 11 By satisfying the above structure, the resistance of the SEI film formed upon reduction of the compound of Formula 1 is prevented from increasing due to long carbon chains, thereby enabling excellent lithium ion mobility. At this time, the R 12 , R 13 , R 14 , and R 15The groups may independently be hydrogen or an alkyl group having 1 to 10 carbon atoms, specifically hydrogen or an alkyl group having 1 to 5 carbon atoms, more specifically hydrogen or an alkyl group having 1 to 3 carbon atoms, and even more specifically hydrogen. In this case, L1 of Formula 1 may be an ether group (*-O-*), an ester group (*-C(=O)O-*), an alkylene group having 1 to 5 carbon atoms, or a combination thereof.

[0088] According to the present invention, L2 of Formula 2 may be an ether group (*-O-*), an ester group (*-C(=O)O-*), an alkylene group having 1 to 5 carbon atoms, or a combination thereof. In this case, R of Formula 2 21 , R 22 , R 23 , R 24 and R 25 The elements may be hydrogen or an alkyl group having 1 to 10 carbon atoms independently of each other, specifically hydrogen or an alkyl group having 1 to 5 carbon atoms, more specifically hydrogen or an alkyl group having 1 to 3 carbon atoms, and even more specifically hydrogen.

[0089] According to the present invention, R of the above chemical formula 3 31 - and R 32 may be an alkyl group having 1 to 5 carbon atoms substituted with one or more fluorines independently of each other, specifically, an alkyl group having 1 to 3 carbon atoms substituted with one or more fluorines. The above R 31 - and R 32 If the above structure is satisfied, the SEI film formed when the compound of Chemical Formula 3 is reduced can prevent resistance from increasing due to long carbon chains, thereby improving the transportability of lithium ions.

[0090] The first compound according to the present invention may be one or more selected from the group consisting of a compound represented by the following chemical formula 1-1 and a compound represented by the following chemical formula 1-2.

[0091] [Chemical Formula 1-1]

[0092]

[0093] [Chemical Formula 1-2]

[0094]

[0095] In the first compound above, the ring structure of the carbonate-based compound is opened, and the proparzyl group performs the role of extending the chain length, thereby enabling the easy formation of a polymeric film. In addition, the ether and ester groups of the first compound contain oxygen and have a large amount of lone pair electrons, so the lithium ion transportability is excellent when forming a film, which can improve the resistance of the film.

[0096] The second compound according to the present invention may be one or more selected from the group consisting of a compound represented by the following chemical formula 2-1 and a compound represented by the following chemical formula 2-2.

[0097] [Chemical Formula 2-1]

[0098]

[0099] [Chemical Formula 2-2]

[0100]

[0101] The second compound is a coumarin-based compound and can promote the ring opening of the first compound through radicals. Additionally, the second compound can lower resistance by including an ether group or an ester group to improve the lithium ion transportability of the film through abundant lone pair electrons, and can form a polymeric film with long chains when forming the film by including a proparzyl group.

[0102] The third compound according to the present invention may be one or more selected from the group consisting of the compound represented by the following chemical formula 3-1 and the compound represented by the following chemical formula 3-2.

[0103] [Chemical Formula 3-1]

[0104]

[0105] [Chemical Formula 3-2]

[0106]

[0107] R of the above third compound 31 - and R 32 The structures may differ from each other. Specifically, the third compound has an asymmetric structure in which each of its ends is substituted with two or more fluorine atoms, and the reducing properties of the oxygen on both sides may differ depending on the length of the carbon atoms on both -O- sides. This can actually promote the reducing properties of the third compound, thereby enabling the smooth formation of a film.

[0108] The first compound according to the present invention may be included in the 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, 0.4 wt% or more, or 0.5 wt% or more, based on the total weight of the non-aqueous electrolyte. The first compound may be included in the non-aqueous electrolyte in an amount of 4 wt% or less, 3 wt% or less, 2 wt% or less, 1.8 wt% or less, 1.6 wt% or less, 1.4 wt% or less, 1.2 wt% or less, or 1.0 wt% or less, based on the total weight of the non-aqueous electrolyte.

[0109] The first compound may be included in the non-aqueous electrolyte in an amount of 0.1 wt% to 4 wt%, specifically 0.1 wt% to 3 wt%, more specifically 0.1 wt% to 2 wt%, more specifically 0.2 wt% to 1.8 wt%, more specifically 0.25 wt% to 1.6 wt%, more specifically 0.3 wt% to 1.4 wt%, more specifically 0.4 wt% to 1.2 wt%, and more specifically 0.5 wt% to 1.0 wt%. When the content of the first compound satisfies the above range, an excellent electrode film with excellent flexibility and recovery properties as described above can be realized, thereby improving the lifespan performance effect of the secondary battery while preventing side reactions caused by the excessive use of additives, thereby preventing an increase in resistance.

[0110] The second compound according to the present invention may be included in the 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, 0.4 wt% or more, or 0.5 wt% or more, based on the total weight of the non-aqueous electrolyte. The second compound may be included in the non-aqueous electrolyte in an amount of 4 wt% or less, 3 wt% or less, 2 wt% or less, 1.8 wt% or less, 1.6 wt% or less, 1.4 wt% or less, 1.2 wt% or less, or 1.0 wt% or less, based on the total weight of the non-aqueous electrolyte.

[0111] The second compound may be included in the non-aqueous electrolyte in an amount of 0.1 wt% to 4 wt%, specifically 0.1 wt% to 3 wt%, more specifically 0.1 wt% to 2 wt%, more specifically 0.2 wt% to 1.8 wt%, more specifically 0.25 wt% to 1.6 wt%, more specifically 0.3 wt% to 1.4 wt%, more specifically 0.4 wt% to 1.2 wt%, and more specifically 0.5 wt% to 1.0 wt%. When the content of the second compound satisfies the above range, the electrode film having excellent high-temperature stability described above can be realized, thereby improving the high-temperature durability performance of the secondary battery while preventing side reactions caused by the excessive use of additives, thereby preventing an increase in resistance.

[0112] The third compound according to the present invention may be included in the 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, 0.4 wt% or more, or 0.5 wt% or more, based on the total weight of the non-aqueous electrolyte. The third compound may be included in the non-aqueous electrolyte in an amount of 4 wt% or less, 3 wt% or less, 2 wt% or less, 1.8 wt% or less, 1.6 wt% or less, 1.4 wt% or less, 1.2 wt% or less, or 1.0 wt% or less, based on the total weight of the non-aqueous electrolyte.

[0113] The above third compound may be included in the non-aqueous electrolyte in an amount of 0.1 wt% to 4 wt%, specifically 0.1 wt% to 3 wt%, more specifically 0.1 wt% to 2 wt%, more specifically 0.2 wt% to 1.8 wt%, more specifically 0.25 wt% to 1.6 wt%, more specifically 0.3 wt% to 1.4 wt%, more specifically 0.4 wt% to 1.2 wt%, and more specifically 0.5 wt% to 1.0 wt%. When the content of the above third compound satisfies the above range, it is possible to achieve an electrode film with excellent mechanical durability as described above, while preventing reduced flexibility and side reactions caused by the excessive use of additives.

[0114]

[0115] (2) Organic solvent

[0116] The organic solvent according to the present invention may include one or more selected from the group consisting of linear carbonate compounds and cyclic carbonate compounds. By including the linear carbonate compounds and / or cyclic carbonate compounds, the organic solvent can improve the solubility, viscosity, and fluidity of the lithium salt in a non-aqueous electrolyte.

[0117] The above linear carbonate-based compound may include one or more selected from the group consisting of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethylmethyl carbonate, methylpropyl carbonate, and ethylpropyl carbonate.

[0118] The above linear carbonate-based compound may be included in the organic solvent in an amount of 35 volume% to 85 volume%, specifically in an amount of 35 volume% or more, 40 volume% or more, 45 volume% or more, 47 volume% or more, 50 volume% or more, 53 volume% or more, 55 volume% or more, or 60 volume% or more. Additionally, the above linear carbonate-based compound may be included in the organic solvent in an amount of 85 volume% or less, 80 volume% or less, 78 volume% or less, 75 volume% or less, 73 volume% or less, or 70 volume% or less. The above numerical ranges may be combined without limitation. When the content of the above linear carbonate-based compound satisfies the above range, the viscosity does not rise excessively while preventing a decrease in the degree of dissociation of the lithium salt in the organic solvent, thereby improving the ionic conductivity of the non-aqueous electrolyte.

[0119] The above cyclic carbonate compound may include at least one selected from the group consisting of ethylene carbonate, fluoroethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate.

[0120] The above cyclic carbonate-based compound may be included in the organic solvent in an amount of 10 volume% to 30 volume%, specifically in an amount of 10 volume% or more, 13 volume% or more, or 15 volume% or more. Additionally, the above cyclic carbonate-based compound may be included in the organic solvent in an amount of 30 volume% or less, 28 volume% or less, 25 volume% or less, or 20 volume% or less. The above numerical ranges may be combined without limitation. When the content of the above cyclic carbonate-based compound satisfies the above range, the degree of dissociation of the lithium salt can be increased while maintaining the viscosity of the organic solvent at an appropriate level, thereby improving the electrochemical stability of the non-aqueous electrolyte.

[0121] The above organic solvent may include a linear carbonate compound and a cyclic carbonate compound. In this case, the ratio of the volume of the cyclic carbonate compound to the volume of the linear carbonate compound may be 0.10 or more, 0.12 or more, 0.15 or more, or 0.20 or more. Additionally, the ratio of the volume of the cyclic carbonate compound to the volume of the linear carbonate compound may be 0.50 or less, 0.45 or less, 0.40 or less, 0.35 or less, or 0.30 or less. It may be 0.10 or more, 0.12 or more, or 0.15 or more. It may be up to 0.50, specifically 0.15 to 0.40, and more specifically 0.15 to 0.25. The above numerical ranges may be combined with one another without limitation. When the above organic solvent satisfies the above range, the viscosity of the organic solvent is appropriately controlled, and the dissociation, movement, and transfer of the lithium salt can be carried out smoothly.

[0122] The above organic solvent may further include at least one selected from the group consisting of linear ester-based organic solvents and cyclic ester-based organic solvents.

[0123] The above linear ester-based organic solvent may specifically include at least one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate.

[0124] The above-mentioned cyclic ester-based organic solvent may specifically include at least one selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0125]

[0126] (3) Lithium salt

[0127] As the lithium salt used in the present invention, various lithium salts commonly used in non-aqueous electrolytes for lithium secondary batteries may be used without limitation. For example, the lithium salt is Li as a cation. + It includes, and as anion, F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO2 - , AlO4 - , AlCl4 - , PF6 - , SbF6 - , AsF6 - , B 10 Cl 10 - , BF2C2O4 - , BC4O8 - , PF4C2O4 - , PF2C4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , C4F9SO3 - , CF3CF2SO3 - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , CH3SO3 - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - It may include at least one selected from a group consisting of

[0128] Specifically, the lithium salt is LiCl, LiBr, LiI, LiBF4, LiClO4, LiAlO2, LiAlO4, LiAlCl4, LiPF6, LiSbF6, LiAsF6, LiB 10 Cl 10 It may include at least one selected from the group consisting of LiBOB (LiB(C2O4)2), LiCF3SO3, LiFSI (LiN(SO2F)2), LiCH3SO3, LiCF3CO2, LiCH3CO2, and LiBETI (LiN(SO2CF2CF3)2). Specifically, the lithium salt may include at least one selected from the group consisting of LiBF4, LiClO4, LiPF6, LiBOB (LiB(C2O4)2), LiCF3SO3, LiTFSI (LiN(SO2CF3)2), LiFSI (LiN(SO2F)2), and LiBETI (LiN(SO2CF2CF3)2). More specifically, the lithium salt may include LiPF6, in which case the effect of the combined use of ethylene carbonate and the compound represented by Formula 1 may be expressed at a desirable level.

[0129] The above lithium salt may be included in the above-mentioned non-aqueous electrolyte at a concentration of 0.5M to 5M, specifically 0.8M to 4M, and more specifically 0.8M to 2.0M. When the concentration of the above-mentioned lithium salt satisfies the above range, the lithium ion yield (Li + The transference number and the degree of dissociation of lithium ions are improved, which can enhance the output characteristics of the battery.

[0130]

[0131] Meanwhile, in addition to the above components, the above-mentioned non-aqueous electrolyte may additionally include auxiliary additives for the purpose of improving the lifespan characteristics of the battery, suppressing the reduction of battery capacity, and improving the discharge capacity of the battery. For example, the above-mentioned non-aqueous electrolyte may include at least one auxiliary additive selected from the group consisting of cyclic carbonate compounds, halogen-substituted carbonate compounds, sulfone compounds, sulfate compounds, phosphate compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds.

[0132] The above auxiliary additive may be included in an amount of 0.1 to 10 weight%, specifically 0.1 to 5 weight%, based on the total weight of the above non-aqueous electrolyte.

[0133]

[0134] lithium secondary battery

[0135] Next, a lithium secondary battery according to the present invention will be described.

[0136] A lithium secondary battery according to the present invention comprises a positive electrode, a negative electrode facing the positive electrode, a separator interposed between the positive electrode and the negative electrode, and the above-described non-aqueous electrolyte. At this time, since the above-described non-aqueous electrolyte is identical to the non-aqueous electrolyte according to the present invention, a detailed description is omitted, and the remaining components excluding the non-aqueous electrolyte will be described below.

[0137]

[0138] (1) positive electrode

[0139] The anode according to the present invention may include an anode active material.

[0140] The above-mentioned cathode active material is a compound capable of reversible intercalation and deintercalation of lithium, and specifically, may include a lithium metal oxide containing 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 Co Z1 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 s2Examples 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.

[0141] Specifically, the above positive active material may include a lithium transition metal oxide represented by the following [Chemical Formula A].

[0142] [Chemical Formula A]

[0143] Li x Ni a Co b M 1 c M 2 d O2

[0144] In the above chemical formula A, 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.

[0145] The above M 2 It 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.

[0146] The above x represents the atomic fraction of lithium in the lithium transition metal oxide, and may be 0.90≤x≤1.1, specifically 0.95≤x≤1.08, more specifically 1.0≤x≤1.08.

[0147] The above a represents the atomic fraction of nickel among metal elements excluding lithium in the lithium transition metal oxide, and may be 0.5≤a<1.0, 0.5≤a≤0.8, 0.5≤a≤0.7, 0.55≤a≤0.7, or 0.6≤a≤0.7. When the nickel content satisfies the above range, high voltage performance and capacitance characteristics may be excellent.

[0148] 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.

[0149] 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.

[0150] 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.

[0151] The above-mentioned positive electrode active material may include single-particle particles. The single-particle particles may be in the form of a single particle consisting of one nodule and / or a pseudo-single particle which is a complex of 30 or fewer nodules. When the above-mentioned positive electrode active material includes single-particle particles, particle breakage during the rolling process is reduced compared to secondary particle-based positive electrode active materials, and structural stability can be improved under high temperature and / or high voltage conditions. As a result, the positive electrode containing single-particle particles can minimize degradation under high temperature / high voltage conditions, and the generation of fine particles during the manufacturing process is reduced, thereby reducing gas generation due to side reactions with the electrolyte. Therefore, by including single-particle particles in the above-mentioned positive electrode active material, a secondary battery with excellent cycle characteristics can be realized.

[0152] Average particle size (D) of the above positive active material50 The particle size may be 0.1㎛ to 10㎛, specifically 0.5㎛ to 8㎛, and more specifically 1㎛ to 4㎛. In this case, particle breakage is minimized during electrode manufacturing, and the increase in resistance can be suppressed more effectively.

[0153] Minimum particle size (D) of the above positive active material min ) can be 0.01㎛ to 5.0㎛, specifically 0.1㎛ to 1.0㎛, more specifically 0.2㎛ to 0.8㎛. In this case, particle breakage is minimized during the rolling process, and thermal safety can be ensured.

[0154] Maximum particle size (D) of the above positive active material max ) may be 5㎛ to 15㎛, specifically 6㎛ to 10㎛, more specifically 7㎛ to 10㎛. The maximum particle size (D) of the positive electrode active material may be 5㎛ to 15㎛, specifically 6㎛ to 10㎛, and more specifically 7㎛ to 10㎛. max When the above range is satisfied, the resistance and capacitance characteristics may be even better.

[0155] The BET specific surface area of ​​the above positive active material is 0.05 m² 2 / g to 3m 2 / g, specifically 0.05m 2 / g to 1.5m 2 / g, specifically 0.1m 2 / g to 1.2m 2 / g, more specifically 0.15m 2 / g to 1m 2 It can be / g. In this case, lithium migration beneath the anode surface proceeds smoothly, and high-temperature durability can be improved by suppressing side reactions.

[0156]

[0157] The above positive electrode may include a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector.

[0158] 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.

[0159] The thickness of the above positive current collector can typically be 3 to 500 μm.

[0160] The above positive active material layer may be disposed on one or both sides of the positive current collector.

[0161] The above positive active material layer may include the aforementioned positive active material. The positive active material may be included in an amount of 60 to 99 weight%, specifically 70 to 99 weight%, more specifically 80 to 98 weight% based on the total weight of the positive active material layer.

[0162] The above-described positive active material layer may optionally further include a binder and / or a conductive material together with the positive active material described above.

[0163] The above binder is a component that assists in the bonding of the positive active material and the conductive material, and in 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, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, and various copolymers.

[0164] The above binder may be included in an amount of 1% to 20% by weight, specifically 1% to 15% by weight, and more specifically 1% to 10% by weight, based on the total weight of the positive active material layer.

[0165] 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.

[0166] The above conductive material may be included in an amount of 1% to 20% by weight, specifically 1% to 15% by weight, and more specifically 1% to 10% by weight, based on the total weight of the positive active material layer.

[0167] 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.

[0168] The 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%, specifically 70 to 95 weight%, and more specifically 70 to 90 weight%.

[0169]

[0170] (2) Cathode

[0171] The cathode according to the present invention may include a cathode active material.

[0172] The above-mentioned negative electrode active material may be a compound capable of reversible intercalation and deintercalation of lithium, for example, carbon materials such as artificial graphite, natural graphite, Kish graphite, pyrolytic carbon, meso-carbon microbeads, mesophase pitches, petroleum or coal tar pitch-derived cokes, mesophase pitch-based carbon fiber, graphitized carbon fiber, amorphous carbon, softened carbon, or hardened carbon; (semi)metallic materials capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, or Al alloys; SiO b(0 <b≤2), SnO2, 바나듐 산화물, 리튬 바나듐 산화물과 같이 리튬을 도프 및 탈도프할 수 있는 (준)금속 산화물 재료; Si-C 복합체 또는 Sn-C 복합체과 같은 이종 복합 재료; 또는 금속 리튬 박막 등을 들 수 있으며, 이들 중 어느 하나 또는 둘 이상의 혼합물이 사용될 수 있다.

[0173] The above-mentioned negative electrode active material may include at least one selected from the group consisting of carbon-based active materials and silicon-based active materials. The above-mentioned carbon-based active material may include at least one selected from the group consisting of artificial graphite, natural graphite, softened carbon, and hardened carbon. The above-mentioned silicon-based active material is 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.

[0174] In addition, the above-mentioned negative electrode active material may be a mixed active material comprising two or more of the above-mentioned materials.

[0175] The above cathode may include a cathode current collector and a cathode active material layer disposed on at least one surface of the cathode current collector.

[0176] 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.

[0177] The above-mentioned negative current collector can typically have a thickness of 3 μm to 500 μm, and specifically, 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.

[0178] The above cathode active material layer may be disposed on one or both sides of the cathode current collector.

[0179] The above-mentioned cathode active material layer may include the aforementioned cathode active material.

[0180] 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, specifically 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 by weight, or 95% or less by weight.

[0181] The above-described cathode active material layer may optionally further include a binder and / or a conductive material together with the cathode active material described above.

[0182] 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. Specifically, carboxymethyl cellulose, hydroxypropylmethyl cellulose, hydroxypropyl cellulose, or a mixture thereof may be applied as a binder.

[0183] The 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, 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. In addition, the conductive material may 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 based on the total weight of the negative electrode active material layer.

[0184] Such conductive materials are not particularly limited as long as they possess conductivity without causing chemical changes in the battery, and for example, graphite such as natural graphite or synthetic graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; conductive fibers such as carbon fibers or metal fibers; fluorinated carbon; metal powders 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 may be used.

[0185] 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.

[0186] 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.

[0187]

[0188] (3) Separator

[0189] The above separator separates the negative and positive electrodes and provides a pathway for the movement of lithium ions; it can be used without any special restrictions as long as it is commonly used as a separator in a lithium secondary battery.

[0190] Specifically, the above-mentioned separator may be a conventional porous polymer film used as a separator, such as a porous polymer film made of a polyolefin-based polymer like ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, used alone or in a laminate thereof, or a conventional porous nonwoven fabric, such as a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc., may be used, but is not limited thereto. In addition, a coated separator containing a ceramic component or a polymer material may be used to ensure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

[0191]

[0192] A lithium secondary battery according to the present invention as described above can be used to manufacture a battery pack. The battery pack comprises an assembly of lithium secondary batteries electrically connected according to the present invention and a pack housing that accommodates the same, wherein the pack housing may include a busbar for electrically connecting the lithium secondary batteries, a cooling unit, an external terminal, etc. The battery pack may be mounted in a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle includes a four-wheeled vehicle or a two-wheeled vehicle. In particular, the lithium secondary battery according to the present invention has high energy density and excellent rapid charging performance, so it can be usefully used as a battery for an electric vehicle.

[0193]

[0194] The present invention will be explained in more detail below through specific embodiments. However, the following embodiments are intended only to aid in understanding the present invention, and the scope of the present invention is not limited to these embodiments.

[0195]

[0196] Example 1

[0197] (Preparation of non-aqueous electrolytes)

[0198] As an organic solvent, a mixture of ethylene carbonate, ethylmethyl carbonate, and diethyl carbonate in a volume ratio of 20:70:10 was used. LiPF6 was dissolved in the organic solvent to a concentration of 1.0 M, and then a non-aqueous electrolyte was prepared by adding a first compound represented by Formula 1-1, a second compound represented by Formula 2-1, and a third compound represented by Formula 3-1 as additives. At this time, each of the compound represented by Formula 1-1, the compound represented by Formula 2-1, and the compound represented by Formula 3-1 was included in amounts of 1.0 wt%, 1.0 wt%, and 1.0 wt%, respectively, based on the total weight of the non-aqueous electrolyte.

[0199] (Manufacturing of lithium secondary batteries)

[0200] Li[Ni as positive electrode active material 0.6 Co 0.1 Mn 0.3 A single-particle cathode active material having the composition of ]O2 was prepared. The cathode active material has a specific surface area (BET) of 1.0 m² 2 / g, and average particle size (D 50 ) is 4.0㎛, minimum particle size (D min ) is 0.2㎛, maximum particle size (D max The thickness is 15.0 μm. Subsequently, the above-mentioned positive active material, conductive material (carbon black), and binder (polyvinylidene fluoride, PVDF) were mixed in N-methylpyrrolidone in a weight ratio of 97.74:0.7:1.56 to prepare a positive slurry. The positive slurry was applied to both sides of an aluminum (Al) current collector with a thickness of 12 μm and dried, and then a positive was manufactured by performing a roll press.

[0201] A cathode slurry was prepared by mixing a cathode active material (a mixture of graphite and a silicon-carbon composite in a weight ratio of 95:5), a conductive material (carbon black), and a binder (styrene-butadiene rubber) in water in a weight ratio of 70.0:20.3:9.7. The cathode slurry was applied to both sides of a copper (Cu) current collector with a thickness of 15 μm and dried, and then a roll press was performed to manufacture a cathode.

[0202] 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.

[0203]

[0204] Example 2

[0205] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1, except that a compound represented by the above chemical formula 1-1 was added to the non-aqueous electrolyte in an amount of 0.5 wt% relative to the total weight of the non-aqueous electrolyte.

[0206]

[0207] Example 3

[0208] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1, except that a compound represented by the above chemical formula 1-1 was added to the non-aqueous electrolyte in an amount of 2.0 wt% relative to the total weight of the non-aqueous electrolyte.

[0209]

[0210] Example 4

[0211] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1, except that a compound represented by Chemical Formula 2-1 was added to the non-aqueous electrolyte in an amount of 0.5% by weight relative to the total weight of the non-aqueous electrolyte.

[0212]

[0213] Example 5

[0214] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1, except that a compound represented by Chemical Formula 2-1 was added to the non-aqueous electrolyte in an amount of 2.0 wt% relative to the total weight of the non-aqueous electrolyte.

[0215]

[0216] Example 6

[0217] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1, except that a compound represented by Chemical Formula 3-1 was added to the non-aqueous electrolyte in an amount of 0.5% by weight relative to the total weight of the non-aqueous electrolyte.

[0218]

[0219] Example 7

[0220] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1, except that a compound represented by Chemical Formula 3-1 was added to the non-aqueous electrolyte in an amount of 2.0 wt% relative to the total weight of the non-aqueous electrolyte.

[0221]

[0222] Example 8

[0223] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1, except that instead of the first compound represented by Chemical Formula 1-1, a compound represented by Chemical Formula 1-2 was added to the non-aqueous electrolyte in an amount of 1.0% by weight relative to the total weight of the non-aqueous electrolyte.

[0224]

[0225] Example 9

[0226] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1, except that a compound represented by Chemical Formula 2-2 was added to the non-aqueous electrolyte as the second compound in an amount of 1.0% by weight relative to the total weight of the non-aqueous electrolyte.

[0227]

[0228] Example 10

[0229] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1, except that a compound represented by Chemical Formula 3-2 was added to the non-aqueous electrolyte as the third compound in an amount of 1.0 wt% relative to the total weight of the non-aqueous electrolyte instead of the compound represented by Chemical Formula 3-1.

[0230]

[0231] Comparative Example 1

[0232] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1 above, except that no additives were added.

[0233]

[0234] Comparative Example 2

[0235] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1, except that the second and third additives were not added as additives.

[0236]

[0237] Comparative Example 3

[0238] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1, except that the first and third additives were not added as additives.

[0239]

[0240] Comparative Example 4

[0241] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1, except that the first and second additives were not added as additives.

[0242]

[0243] Comparative Example 5

[0244] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1, except that the first compound was not added to the non-aqueous electrolyte.

[0245]

[0246] Comparative Example 6

[0247] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1, except that the second compound was not added to the non-aqueous electrolyte.

[0248]

[0249] Comparative Example 7

[0250] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1, except that the above-mentioned third compound was not added to the non-aqueous electrolyte.

[0251]

[0252] Additive 1 Additive 2 Additive 3 Type Content (Wet%) Type Content (Wet%) Type Content (Wet%) Example 1 Chemical Formula 1-11.0 Chemical Formula 2-11.0 Chemical Formula 3-11.0 Example 2 Chemical Formula 1-10.5 Chemical Formula 2-11.0 Chemical Formula 3-11.0 Example 3 Chemical Formula 1-12.0 Chemical Formula 2-11.0 Chemical Formula 3-11.0 Example 4 Chemical Formula 1-11.0 Chemical Formula 2-10.5 Chemical Formula 3-11.0 Example 5 Chemical Formula 1-11.0 Chemical Formula 2-12.0 Chemical Formula 3-11.0 Example 6 Chemical Formula 1-11.0 Chemical Formula 2-11.0 Chemical Formula 3-10.5 Example 7 Chemical Formula 1-11.0 Chemical Formula 2-11.0 Chemical Formula 3-12.0 Example 8 Chemical Formula 1-21.0 Chemical Formula 2-11.0 Chemical Formula 3-11.0 Example 9 Chemical Formula 1-11.0 Chemical Formula 2-21.0 Chemical Formula 3-11.0 Example 10 Chemical Formula 1-11.0 Chemical Formula 2-11.0 Chemical Formula 3-21.0 Comparative Example 1------Comparative Example 2 Chemical Formula 1-11.0----Comparative Example 3--Chemical Formula 2-11.0--Comparative Example 4----Chemical Formula 3-11.0 Comparative Example 5--Chemical Formula 2-11.0 Chemical Formula 3-11.0 Comparative Example 6 Chemical Formula 1-11.0--Chemical Formula 3-11.0 Comparative Example 7 Chemical Formula 1-11.0 Chemical Formula 2-11.0--

[0253]

[0254] Experimental Example 1: Evaluation of High-Temperature Cycle Characteristics

[0255] The lithium secondary batteries of Examples 1 to 10 and Comparative Examples 1 to 7 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 300 charge / discharge cycles performed as one cycle.

[0256] The capacity retention rate was calculated using the following formula, and the results are shown in Table 2 below.

[0257] Capacity Retention Rate (%) = (Discharge Capacity after 300 cycles / Discharge Capacity after 1 cycle) × 100

[0258] Volume Retention Rate (%) Example 192.5 Example 288.5 Example 386.3 Example 487.3 Example 585.4 Example 687.5 Example 786.9 Example 887.2 Example 986.1 Example 1086.9 Comparative Example 168.6 Comparative Example 269.4 Comparative Example 370.9 Comparative Example 471.6 Comparative Example 572.8 Comparative Example 671.7 Comparative Example 770.6

[0259]

[0260] Referring to Table 2 above, it can be seen that the lithium secondary batteries of Examples 1 to 10 have significantly superior cycle characteristics at high temperatures compared to the lithium secondary batteries of Comparative Examples 1 to 7, which do not contain one or more of the first to third compounds.

[0261] This appears to be because, in the case of the lithium secondary batteries of Examples 1 to 10, a film with excellent flexibility and mechanical durability can be realized due to the combination of the first compound, the second compound, and the third compound, and as a result, high-temperature performance is improved.

[0262] On the other hand, the lithium secondary batteries of Comparative Examples 2 to 7 lack one or more of the first to third compounds as additives, so the synergistic effect between the compounds is not sufficiently expressed, and accordingly, the flexibility and / or mechanical durability of the electrode film is reduced, and it is determined that the high-temperature cycle characteristics are relatively degraded.

[0263]

[0264] Experimental Example 2: Evaluation of High-Temperature Storage Characteristics

[0265] The lithium secondary batteries of Examples 1 to 10 and Comparative Examples 1 to 7 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 / discharge, and then charged to 4.4V and 0.05C under CC / CV and 0.33C conditions at 25℃, and then stored at 60℃ for 8 weeks.

[0266] After 8 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. The capacity retention rate was evaluated according to the following formula, and the results are shown in Table 3 below.

[0267] Capacity Retention Rate (%) = (Discharge Capacity after 8 weeks of storage / Initial Discharge Capacity) × 100

[0268] Volume Retention Rate (%) Example 195.3 Example 291.0 Example 388.6 Example 489.3 Example 587.7 Example 689.4 Example 788.1 Example 890.6 Example 989.4 Example 1089.7 Comparative Example 170.5 Comparative Example 272.0 Comparative Example 373.6 Comparative Example 474.9 Comparative Example 575.6 Comparative Example 673.9 Comparative Example 772.1

[0269]

[0270] Referring to Table 3 above, it can be seen that the lithium secondary batteries of Examples 1 to 10 have significantly superior high-temperature storage characteristics compared to Comparative Example 1, which does not contain additives.

[0271] In addition, it can be confirmed that the lithium secondary batteries of Examples 1 to 10, which include all of the first to third compounds as additives, have a significantly higher capacity retention rate compared to Comparative Examples 2 to 7, which do not include one or more of the first to third compounds. Specifically, Comparative Examples 2 to 4 include only one type of compound among the first to third compounds as an additive, so it is determined that the improvement in high-temperature storage performance is low because no synergistic effect between the compounds is exhibited. Furthermore, in Comparative Example 5, the absence of the first compound makes it difficult to form a polymeric film, resulting in reduced flexibility of the film. Similarly, in Comparative Example 6, the absence of the second compound makes it difficult to promote ring opening of the first compound, failing to improve film flexibility. Consequently, film damage occurs due to the expansion of the active material, and it is determined that high-temperature performance is reduced as a result. Additionally, in Comparative Example 7, the absence of the third compound appears to reduce the mechanical durability of the film, leading to a decrease in capacity retention rate.

Claims

It includes lithium salt, organic solvent, and additives, The above additive is a non-aqueous electrolyte comprising a first compound represented by the following chemical formula 1, a second compound represented by the following chemical formula 2, and a third compound represented by the following chemical formula 3: [Chemical Formula 1] [Chemical Formula 2] [Chemical Formula 3] In the above Chemical Formulas 1 and 2, R 11 , R 12 , R 13 , R 14 , R 15 , R 21 , R 22 , R 23 , R 24 and R 25 are independently hydrogen or alkyl groups having 1 to 10 carbon atoms, and L1 and L2 are independently directly bonded to each other, ether groups (*-O-*), ester groups (*-C(=O)O-*), alkylene groups having 1 to 5 carbon atoms, or combinations thereof, and In the above chemical formula 3, R 31 - and R 32 is an alkyl group having 1 to 10 carbon atoms, with one or more fluorine atoms independently substituted. In claim 1, R of the above chemical formula 1 11 A non-aqueous electrolyte that is an alkyl group having 1 to 5 carbon atoms. In claim 1, R of the above chemical formula 3 31 - and R 32 A non-aqueous electrolyte that is a carbon-1 to carbon-5 alkyl group, with one or more fluorine groups independently substituted. In claim 1, A non-aqueous electrolyte comprising one or more selected from the group consisting of compounds represented by the following chemical formulas 1-1 and 1-2: [Chemical Formula 1-1] [Chemical Formula 1-2] . In claim 1, A non-aqueous electrolyte comprising one or more selected from the group consisting of compounds represented by the following chemical formulas 2-1 and 2-2: [Chemical Formula 2-1] [Chemical Formula 2-2] . In claim 1, A non-aqueous electrolyte comprising one or more selected from the group consisting of compounds represented by the following chemical formulas 3-1 and 3-2: [Chemical Formula 3-1] [Chemical Formula 3-2] . In claim 1, The first compound is a non-aqueous electrolyte included in the non-aqueous electrolyte in an amount of 0.1% to 4% by weight. In claim 1, The second compound is a non-aqueous electrolyte included in the non-aqueous electrolyte at a concentration of 0.1% to 4% by weight. In claim 1, The above third compound is a non-aqueous electrolyte included in the above non-aqueous electrolyte at a concentration of 0.1% to 4% by weight. In claim 1, The above organic solvent is a non-aqueous electrolyte comprising one or more selected from the group consisting of linear carbonate compounds and cyclic carbonate compounds. anode; A cathode opposite to the anode above; A separator interposed between the anode and the cathode; and A lithium secondary battery comprising a non-aqueous electrolyte according to claim 1. In claim 11, The above cathode includes a cathode active material, and A lithium secondary battery comprising at least one type selected from the group consisting of carbon-based active materials and silicon-based active materials, wherein the above-mentioned negative electrode active material. In claim 12, The above silicon-based active material is silicon, silicon oxide (SiO₂). x , 0 <x<2) 및 실리콘-탄소 복합체로 이루어진 군에서 선택된 적어도 1종을 포함하는 리튬 이차전지. In claim 12, The above silicon-based active material is a lithium secondary battery comprising a silicon-carbon composite.

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