Non-aqueous electrolyte and secondary lithium battery, including the same

Description

1 / 40 “NON-AQUEOUS ELECTROLYTE AND LITHIUM SECONDARY BATTERY, INCLUDING THE SAME” TECHNICAL FIELD

[001] This disclosure relates to a non-aqueous electrolyte and a lithium secondary battery, including them. TECHNIQUE BACKGROUND

[002] There is a need to develop technology to store and use electrical energy efficiently, as personal IT devices and computer networks are developed with the recent development of the information society and the consequent dependence of society as a whole on the increasing supply of electrical energy.

[003] A secondary battery is a more suitable technology for various applications among the technologies developed and, among secondary batteries, a lithium secondary battery, which can be miniaturized to be applicable to a personal IT device and has the highest energy density, stands out.

[004] Lithium secondary batteries are generally prepared by injecting or impregnating a non-aqueous electrolyte into an electrode assembly comprising a positive electrode, a negative electrode and a porous separator.

[005] Lithium-containing cobalt oxides, LiMnO2 having a layered crystal structure, LiMn2O4 having a spinel crystal structure, lithium-containing nickel oxides (LiNiO2), and lithium-nickel-cobalt-manganese transition metal oxides are being considered as the active material for the positive electrode of this secondary lithium battery. Meanwhile, carbon-based active materials, silicon-based active materials, and similar materials are being considered as the electrode active material.

[006] In particular, the importance of high capacity, high efficiency, and long service life characteristics is growing in secondary lithium batteries used in vehicles. To achieve the high capacity of secondary lithium batteries, the use of a positive electrode active material with a high Ni content can be considered, with Petition 870250086070, dated 09 / 23 / 2025, page 10 / 58 2 / 40 high energy density, but low stability, or drive the secondary lithium battery at high voltage.

[007] However, when the secondary lithium battery is activated under the above conditions, as charging and discharging occur, the surface structure of an electrode or a film formed on the positive / negative electrode surface deteriorates due to a side reaction caused by electrolyte deterioration, and thus transition metal ions can be eluted from the positive electrode surface. As described above, since the eluted transition metal ions are electrodeposited on the negative electrode and reduce the passivation capacity of a solid electrolyte interface (SEI) of the negative electrode, a problem occurs in which the negative electrode deteriorates. This secondary battery deterioration phenomenon tends to be further accelerated when the positive electrode potential is increased or when the battery is exposed to high temperatures.

[008] Furthermore, when the secondary lithium battery is used continuously for a long period of time or left at high temperatures, gas is generated, causing the so-called swelling phenomenon, in which the thickness of the battery increases, and it is known that the amount of gas generated in this case depends on the state of the SEI.

[009] Therefore, in order to solve such problems, research and development of methods capable of suppressing the elution of metal ions from the positive electrode and forming a stable SEI film on the negative electrode has been attempted, thus reducing the swelling phenomenon of the secondary lithium battery and increasing stability at high temperatures. DISCLOSURE OF THE INVENTION TECHNICAL PROBLEM

[010] One aspect of the present disclosure provides a non-aqueous electrolyte capable of forming a durable film on the negative electrode.

[011] In addition, another aspect of the present disclosure provides a lithium secondary battery including the non-aqueous electrolyte described above and having Petition 870250086070, dated 09 / 23 / 2025, page 11 / 58 3 / 40 features enhanced high-temperature cycle characteristics and high-temperature storage performance, thus improving overall performance. TECHNICAL SOLUTION

[012] [1] The present disclosure provides a non-aqueous electrolyte including a lithium salt, an organic solvent and an additive, wherein the additive includes a compound represented by the following Formula 1. [Formula 1]

[013] In Formula 1 above, Ri is an allyl group or a propargyl group; Fb, Rs, R4 and Rs are each independently selected from hydrogen and an alkyl group with 1 to 5 carbon atoms; L is selected from a single bond and an alkylene group with 1 to 10 carbon atoms; and X is selected from -C(=O)-, -S(=O)- and -S(=O)2-.

[014] [2] The present disclosure provides a non-aqueous electrolyte, wherein in [1] above, the Ri above is an allyl group.

[015] [3] The present disclosure provides a non-aqueous electrolyte, wherein in [1] or [2] above, X is selected from -C(=O)- and -S(=O)-.

[016] [4] The present disclosure provides a non-aqueous electrolyte, wherein in at least one of [1] to [3] above, the above R2, Rs, R4 and Rs are each independently an alkyl group with 1 to 5 carbon atoms.

[017] [5] This disclosure provides a non-aqueous electrolyte, wherein in at least one of items [1] to [4] above, the compound represented by Formula 1 above includes at least one selected from the group consisting of compounds Petition 870250086070, dated 09 / 23 / 2025, p. 12 / 58 4 / 40 represented by Formula 1-A, Formula 1-B, Formula 1-C, Formula 2-A, Formula 2-B and Formula 2-C below. [Formula 1-A] [Formula 1-B] [Formula 2-A] [Formula 2-B] Petition 870250086070, dated 09 / 23 / 2025, p. 13 / 58 5 / 40

[018] In Formula 1-A, Formula 1-B, Formula 1-C, Formula 2-A, Formula 2-B and Formula 2-C above, Fb, R3, R4 and Rs are as defined in Formula 1 above.

[019] [6] The present disclosure provides a non-aqueous electrolyte, wherein in at least one of items [1] to [5] above, the compound represented by Formula 1 above includes at least one selected from the group consisting of compounds represented by Formula 1-A-1, Formula 1-A-2, Formula 1-B-1, Formula 1-B-2, Formula 1-C-1, Formula 1-C-2, Formula 2-A-1, Formula 2-A-2, Formula 2-B-1, Formula 2-B-2, Formula 2-C-1 and Formula 2-C-2 below. [Formula 1-A-1] [Formula 1-A-2] Petition 870250086070, dated 09 / 23 / 2025, p. 14 / 58 6 / 40 [Formula 1-B-2] [Formula 1-C-1] Petition 870250086070, dated 09 / 23 / 2025, p. 15 / 58 7 / 40 [Formula 1-C-2] [Formula 2-A-1] [Formula 2-A-2] Petition 870250086070, dated 09 / 23 / 2025, p. 16 / 58 8 / 40 [Formula 2-B-1] [Formula 2-C-2] Petition 870250086070, dated 09 / 23 / 2025, page 17 / 58 9 / 40

[020] [7] The present disclosure provides a non-aqueous electrolyte, wherein in at least one of items [1] to [6] above, the compound represented by Formula 1 above is included in an amount of 0.01% by weight to 10.0% by weight based on the weight of the non-aqueous electrolyte.

[021] [8] The present disclosure provides a non-aqueous electrolyte, wherein in at least one of items [1] to [7] above, the lithium salt includes at least one selected from the group consisting of LiCI, LiBr, Lil, L1BF4, LiCICU, L1AIO4, LiAICk, LiPFe, LiSbFe, LiAsFe, LÍB10CI10, LiBOB(LiB(C2O4)2), LÍCF3SO3, LiFSI(LiN(SO2F)2), LÍCH3SO3, LiCF3CO2, LÍCH3CO2e LiBETI(LiN(SO2CF2CF3)2).

[022] [9] The present disclosure provides a non-aqueous electrolyte, wherein in at least one of items [1] to [8] above, the lithium salt is included in the non-aqueous electrolyte at a molar concentration of 0.5 M to 5.0 M.

[023]

[10] The present disclosure provides a non-aqueous electrolyte, wherein in at least one of items [1] to [9] above, the organic solvent includes at least one selected from the group consisting of a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, a linear ester-based organic solvent and a cyclic ester-based organic solvent.

[024]

[11] The lithium secondary battery according to the present disclosure includes a positive electrode, a negative electrode facing the positive electrode, a separator disposed between the positive electrode and the negative electrode and a non-aqueous electrolyte according to at least one of items [1] to

[10] above. Petition 870250086070, dated 09 / 23 / 2025, page 18 / 58 10 / 40 ADVANTAGEOUS EFFECTS

[025] The non-aqueous electrolyte of the present disclosure is characterized by the use of a cyclic borate-based compound containing an allyl group or a propargyl group in its structure as an additive. The cyclic borate-based compound according to the present disclosure can form a highly durable SEI film due to its high density, while promoting lithium transport characteristics after reduction at the negative electrode. In this regard, the allyl group or propargyl group included in the cyclic borate-based compound can facilitate the access of the cyclic borate-based compound to the negative electrode during negative electrode reduction and improve reactivity, further facilitating the formation of the SEI film derived from the cyclic borate-based compound described above.Consequently, a secondary lithium battery including non-aqueous electrolyte according to this disclosure may exhibit improved service life and storage performance, particularly improved service life and storage performance at high temperatures and high voltages. METHOD OF CARRYING OUT THE INVENTION

[026] It is understood that the terms or words used in this disclosure and claims should not be interpreted as limited to having meanings defined in commonly used dictionaries, but should be interpreted as having meanings and concepts consistent with the technical idea of ​​this disclosure based on the principle that an inventor can appropriately define the concepts of the terms to better explain the invention.

[027] It should also be understood that the terms “include”, “comprise” or “have” in this disclosure specify the presence of features, numbers, stages, elements or combinations thereof, but do not preclude the presence or addition of one or more other features, numbers, stages, elements or combinations thereof.

[028] However, before describing aspects of this disclosure, unless otherwise specified in this disclosure, the expression “*” Petition 870250086070, dated 09 / 23 / 2025, p. 19 / 58 11 / 40 denotes the same atom, a different atom, or a connected portion (bonding site) between the ends of a formula.

[029] Furthermore, the expressions “a” and “b” in the description of “carbon atoms of aab” in the disclosure each denote the number of carbon atoms included in a specific functional group. That is, the functional group may include carbon atoms from “a” to “b”. For example, an “alkyl group with 1 to 5 carbon atoms” means an alkyl group containing 1 to 5 carbon atoms, i.e., CH3-, CH3CH2-, CH3CH2CH2-, (CH3)2CH-, CH3CH2CH2CH2-, (CH3)2CHCH2-, CH3CH2CH2CH2CH2-, (CH3)2CHCH2CH2-, or similar.

[030] Furthermore, in this disclosure, an alkyl group or an aryl group may be substituted or unsubstituted. Unless otherwise defined, the term “substituted” means that at least one hydrogen atom bonded to carbon is replaced by an element other than hydrogen and, for example, means being replaced by an alkyl group with 1 to 20 carbon atoms, an alkenyl group with 2 to 20 carbon atoms, an alkynyl group with 2 to 20 carbon atoms, an alkoxy group with 1 to 20 carbon atoms, a cycloalkyl group with 3 to 12 carbon atoms, a cycloalkenyl group with 3 to 12 carbon atoms, a cycloalkynyl group with 3 to 12 carbon atoms, a heterocycloalkyl group with 3 to 12 carbon atoms, a heterocycloalkenyl group with 3 to 12 carbon atoms, a heterocycloalkynyl group with 2 to 12 carbon atoms, an aryloxy group with 6 to 12 carbon atoms, a halogen atom, a group fluoroalkyl with 1 to 20 carbon atoms, a nitro group,an aryl group with 6 to 20 carbon atoms, a heteroaryl group with 2 to 20 carbon atoms, a haloaryl group with 6 to 20 carbon atoms, etc.

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

[032] The secondary lithium battery and / or non-aqueous electrolyte according to this disclosure may include at least one of the constitutions disclosed below and may include any technically feasible combination of constitutions among the following constitutions. Petition 870250086070, dated 09 / 23 / 2025, p. 20 / 58 12 / 40 Non-aqueous electrolyte

[033] This disclosure refers to a non-aqueous electrolyte.

[034] Specifically, the present disclosure provides a non-aqueous electrolyte comprising a lithium salt, an organic solvent and an additive, wherein the additive includes a compound represented by the following Formula 1.

[035] [Formula 1]

[036] In Formula 1 above, Ri is an allyl group or a propargyl group; R2, R3, R4 and Rs are each independently selected from hydrogen and an alkyl group with 1 to 5 carbon atoms; L is selected from a single bond and an alkylene group with 1 to 10 carbon atoms; and X is selected from -C(=O)-, -S(=O)- and -S(=O)2-. (1) Lithium salt

[037] Like the lithium salt used in the present disclosure, various lithium salts commonly used in a non-aqueous electrolyte for a secondary lithium battery may be used without limitation. For example, lithium salt may include Li+ as a cation and may include at least one selected from the group consisting of F-, Cl·, Br, I-, NO3-, N(CN)2-, BF4-, ClO4-, AlO4-, AlKl-, PF6-, SbF6-, AsF6-, BioCho', 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 as an anion.

[038] Specifically, the lithium salt includes at least one selected from the group consisting of LiCl, LiBr, Lil, L1BF4, L1CIO4, L1AIO4, LiAICk, LiPFe, LiSbFe, Petition 870250086070, dated 09 / 23 / 2025, p. 21 / 58 13 / 40 LiAsF6, LiBioClio, LiBOB (LiB(C2O4)2), UCF3SO3, LiFSI (LiN(SO2F)2), LÍCH3SO3, UCF3CO2, LÍCH3CO2 and LiBETI (LiN(SO2CF2CF3)2). Specifically, the lithium salt includes at least one selected from the group consisting of LiBF4, LiClO4, LiPF6, LiBOB (LiB(C2O4)2), UCF3SO3, LiTFSI (LiN(SO2CF3)2), LiFSI (LiN(SO2F)2) and LiBETI (LiN(SO2CF2CF3)2).

[039] Lithium salt can be included in the non-aqueous electrolyte at a concentration of 0.5 M to 5.0 M, specifically 0.8 M to 4.0 M and, more specifically, 0.8 M to 2.0 M. In the case where the lithium salt concentration meets the above range, this can improve the Li+ transfer number and the degree of dissociation of lithium ions, thus improving the battery output characteristics. (2) Organic Solvent

[040] Organic solvent is a non-aqueous solvent commonly used in secondary lithium batteries and is not limited as long as decomposition due to an oxidation or similar reaction during battery charging and discharging can be minimized.

[041] Specifically, the organic solvent may include at least one selected from among a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, a linear ester-based organic solvent and a cyclic ester-based organic solvent.

[042] Specifically, the organic solvent may include a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, or a mixture thereof.

[043] A cyclic carbonate-based organic solvent is an organic solvent with high viscosity and a high dielectric constant and, therefore, is an organic solvent capable of well dissociating a lithium salt in an electrolyte; specific examples thereof may include at least one organic solvent selected from ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate and vinylene carbonate and, more specifically, may Petition 870250086070, dated 09 / 23 / 2025, page 22 / 58 14 / 40 include at least one selected from the group consisting of ethylene carbonate (EC) and fluoroethylene carbonate (FEC).

[044] In addition, the linear carbonate-based organic solvent is an organic solvent with low viscosity and low dielectric constant, specifically it may include at least one organic solvent selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl carbonate and ethylpropyl carbonate and, more specifically, it may include at least one selected from ethylmethyl carbonate (EMC) and diethyl carbonate (DEC).

[045] Specifically, the organic solvent may be a mixture of a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent. The cyclic carbonate-based organic solvent and the linear carbonate-based organic solvent may be mixed in a volume ratio of 5:95 to 40:60 and, specifically, of 7:93 to 25:75. When the mixing ratio of the cyclic carbonate-based organic solvent and the linear carbonate-based organic solvent satisfies the above range, the characteristics of high dielectric constant and low viscosity can be simultaneously satisfied, resulting in excellent ionic conductivity.

[046] In addition, to prepare an electrolyte with high ionic conductivity, the organic solvent may additionally include at least one ester-based organic solvent selected from a linear ester-based organic solvent and a cyclic ester-based organic solvent, as well as at least one carbonate-based organic solvent selected from a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent.

[047] The linear ester-based organic solvent may include at least one selected from methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate and butyl propionate. Petition 870250086070, dated 09 / 23 / 2025, page 23 / 58 15 / 40

[048] In addition, the 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.

[049] Meanwhile, the organic solvent may be used by adding organic solvents commonly used in non-aqueous electrolytes, without limitation, if necessary. For example, it may additionally include at least one organic solvent selected from an ether-based organic solvent, a glime-based solvent and a nitrile-based organic solvent.

[050] Any of, but not limited to, dimethyl ether, diethyl ether, dipropyl ether, methylethyl ether, methylpropyl ether, ethylpropyl ether, 1,3-dioxolane (DOL) and 2,2-bis(trifluoromethyl)-1,3-dioxolane (TFDOL) may be used as an ether-based solvent.

[051] Glyme-based solvent has a high dielectric constant and low surface tension compared to linear carbonate-based organic solvents, and may include at least one selected from dimethoxyethane (glime, DME), dietoxyethane, digylme, triglyme and tetraglyme (TEGDME) as a solvent with low reactivity with metals, but is not limited to these.

[052] The nitrile-based solvent may include at least one selected from the group consisting of, but is not limited to, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanonitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile and 4-fluorophenylacetonitrile. (3) Additive

[053] The non-aqueous electrolyte includes an additive.

[054] The additive includes a compound represented by the following Formula 1. [Formula 1] Petition 870250086070, dated 09 / 23 / 2025, page 24 / 58 16 / 40

[055] In Formula 1 above, Ri is an allyl group or a propargyl group; R2, R3, R4 and Rs are each independently selected from hydrogen and an alkyl group with 1 to 5 carbon atoms; L is selected from a single bond and an alkylene group with 1 to 10 carbon atoms; and X is selected from -C(=O)-, -S(=O)- and -S(=O)2-.

[056] The compound represented by Formula 1 above is reduced at the negative electrode, thus forming a highly durable SEI film with excellent lithium transport characteristics and high density at the negative electrode.

[057] Generally, cyclic borates are substances capable of forming an SEI film after reduction at the negative electrode, but after being solvated with an organic solvent, they become too bulky to access the negative electrode, and this reduced accessibility becomes a factor that hinders the reactions during the reduction at the negative electrode. In this regard, the compound represented by Formula 1 according to the present disclosure is characterized by an allyl group (-CH2CH=CH2) or a propargyl group (-CFte-C^CH) in the structure being attached to a cyclic borate. Since the allyl or propargyl group has high reactivity due to its LUMO characteristics and is easily accessible to the negative electrode, the cyclic borate combined with the allyl or propargyl group also becomes easily accessible to the negative electrode, and thus the reactivity of the cyclic borate at the negative electrode can be promoted.These effects cannot be achieved with substituents other than allyl and propargyl groups (such as alkyl groups). Petition 870250086070, dated 09 / 23 / 2025, page 25 / 58 17 / 40

[058] In Formula 1 above, Ri can be an allyl group or a propargyl group and, more specifically, it can be an allyl group.

[059] In Formula 1 above, R2, R3, R4 and R5 can each be independently selected from hydrogen and an alkyl group having from 1 to 5 carbon atoms, specifically they can each be independently an alkyl group having from 1 to 5 carbon atoms, more specifically they can each be independently an alkyl group having from 1 to 3 carbon atoms, even more specifically they can each be independently selected from a methyl group and an ethyl group, and even more specifically they can be a methyl group. In the types described above, R2, R3, R4 and R5 can achieve the effect of forming an SEI film with stable reactivity and excellent durability, without inhibiting the effect resulting from the combination of cyclic borate with an allyl group or a propargyl group.

[060] In Formula 1 above, L can be selected from a single bond and an alkylene group with 1 to 10 carbon atoms, and the effects of improving the accessibility of the negative electrode and the reactivity of the cyclic borate according to a vinyl group or a propargyl group can be easily achieved within the range above. In Formula 1 above, L can be selected from a single bond and an alkylene group with 1 to 3 carbon atoms and, specifically, it can be a single bond.

[061] In Formula 1 above, X is selected from -C(=O)-, -S(=O)-, and -S(=O)2-. X connects a cyclic borate with an alkyl group or a propargyl group and can contribute to improving lithium transport characteristics, film durability, and oxidation resistance during SEI film formation. In Formula 1 above, X can be specifically selected from -C(=O)- and -S(=O)-.

[062] Specifically, the compound represented by Formula 1 above includes at least one compound selected from the group consisting of compounds represented by Formula 1-A, Formula 1-B, Formula 1-C, Formula 2-A, Formula 2-B, and Formula 2-C below. More specifically, the compound represented by Formula 1 above includes at least one compound selected from the group consisting Petition 870250086070, dated 09 / 23 / 2025, p. 26 / 58 18 / 40 in compounds shown by Formula 1-A, Formula 1-B and Formula 1-C below. More specifically, the compound represented by Formula 1 above includes at least one compound selected from the group consisting of compounds represented by Formula 1-A and Formula 1-B below. [Formula 1-A] [Formula 1-B] [Formula 1-C] [Formula 2-A] Petition 870250086070, dated 09 / 23 / 2025, p. 27 / 58 19 / 40 [Formula 2-B]

[063] In Formula 1-A, Formula 1-B, Formula 1-C, Formula 2-A, Formula 2-B and Formula 2-C above, Fb, Fb, Fb and Rs are as defined in Formula 1 above.

[064] The compound represented by Formula 1 above may include at least one selected from the group consisting of compounds represented by the following Formulas 1-A-1, 1-A-2, 1-B-1, 1-B-2, 1-C-1, 1-C-2, 2-A-1, 2-A-2, 2-B-1, 2-B-2, 2-C-1 and 2-C-2, specifically it may include at least one selected from the group consisting of compounds represented by the following Formulas 1-A-1, 1-A-2, 1-B-1, 1-B-2, 1-C-2, more specifically it may include at least one selected from the group consisting of compounds represented by the following Formulas 1-A-1, 1-A-2, 1-B-1 and 1-B-2, and even more specifically it may include at least one selected from the group consisting of compounds represented by the following Formulas 1-A-1 and 1-A-2. [Formula 1-A-1] Petition 870250086070, dated 09 / 23 / 2025, p. 28 / 58 20 / 40 [Formula 1-B-2] Petition 870250086070, dated 09 / 23 / 2025, p. 29 / 58 21 / 40 [Formula 1-C-1] [Formula 2-A-1] Petition 870250086070, dated 09 / 23 / 2025, p. 30 / 58 22 / 40 [Formula 2-A-2] [Formula 2-B-1] [Formula 2-B-2] Petition 870250086070, dated 09 / 23 / 2025, p. 31 / 58 23 / 40 [Formula 2-C-1]

[065] Specifically, the compound represented by Formula 1 above can be included in an amount of 0.01% by weight to 10% by weight, specifically, 0.05% by weight to 5.0% by weight and, more specifically, 2.0% by weight to 4.0% by weight, based on the total weight of the non-aqueous electrolyte. When the compound represented by Formula 1 above is used within the described range, an increase in resistance can be avoided when added in excess, while at the same time Petition 870250086070, dated 09 / 23 / 2025, page 32 / 58 24 / 40 which allows the formation of a flexible and highly durable SEI film on the negative electrode.

[066] The additive may additionally include an additional additive along with the compound represented by Formula 1. The additional additive may be included in the non-aqueous electrolyte to prevent the non-aqueous electrolyte from decomposing and causing the negative electrode to collapse in a high-output environment, or to further improve the high-rate discharge characteristics at low temperature, high-temperature stability, overcharge protection, and a suppressive effect on battery swelling at high temperatures.

[067] Specifically, the additional additive may include at least one selected from the group consisting of lithium difluorophosphate (LiDFP), vinylene carbonate, vinylethylene carbonate, fluoroethylene carbonate, propanesulfonate, propenesulfonate, succinonitrile, adiponitrile, ethylene sulfate, lithium bis-(oxalato)borate (LiBOB), lithium difluorophosphate (LiDFP), tris(trimethylsilyl) phosphate (TMSPa) and tris(trimethylsilyl) phosphite (TMSPi), and specifically may include lithium difluorophosphate (LiDFP).

[068] The additional additive may be included in an amount of 0.1% by weight to 15.0% by weight and, specifically, 0.3% by weight to 3.0% by weight in the non-aqueous electrolyte.

[069] When the non-aqueous electrolyte additionally includes the additional additive, the weight ratio of the compound represented by Formula 1 above and the additional additive can be from 45:55 to 99:1, specifically from 50:50 to 95:5, and more specifically from 70:30 to 85:15. When the ratio is within the above ranges, the shelf life performance and high-temperature storage performance can be improved to a more desirable level. Secondary lithium battery

[070] In addition, the present disclosure provides a lithium secondary battery comprising the non-aqueous electrolyte mentioned above. Petition 870250086070, dated 09 / 23 / 2025, page 33 / 58 25 / 40

[071] Specifically, the lithium secondary battery according to the present disclosure includes a positive electrode, a negative electrode facing the positive electrode, a separator disposed between the positive electrode and the negative electrode, and the non-aqueous electrolyte described above.

[072] After a set of electrodes, in which the positive electrode, the negative electrode facing the positive electrode and the separator interposed between the positive and negative electrodes are included, is accommodated in a battery case, the secondary lithium battery can be prepared by injecting the non-aqueous electrolyte into it.

[073] As the non-aqueous electrolyte was described above, the negative electrode, the positive electrode and the separator will be described below. (1) Positive Electrode

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

[075] The positive electrode current collector is not particularly limited, provided it has high conductivity without causing adverse chemical changes in the battery. Specifically, the positive electrode current collector may include at least one selected from copper, stainless steel, aluminum, nickel, titanium, burnt carbon and aluminum-cadmium alloy and, preferably, may include aluminum.

[076] The positive electrode current collector typically has a thickness of 3 to 500 μm.

[077] Microscopic irregularities can be formed on the collector surface to improve the adhesion of the active electrode material. For example, the positive electrode current collector can be used in various formats, such as a film, a sheet, a metal foil, a mesh, a porous body, a foam body, a nonwoven fabric body, and the like.

[078] The active material layer of the positive electrode can be arranged on at least one surface of the positive electrode current collector. Petition 870250086070, dated 09 / 23 / 2025, page 34 / 58 26 / 40 Specifically, the active material layer of the positive electrode can be arranged on one or both surfaces of the positive electrode current collector.

[079] The active material layer of the positive electrode may include an active material of the positive electrode.

[080] The active material of the positive electrode is a compound capable of reversibly intercalating and deintercalating lithium, wherein the active material of the positive electrode may include a lithium transition metal compound oxide, including lithium and at least one transition metal selected from nickel, cobalt, manganese and aluminum, and may preferably include a lithium transition metal compound oxide, including lithium and transition metals, including nickel, cobalt and manganese.

[081] Examples of lithium transition metal compound oxides include 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.), a lithium-nickel-manganese based oxide (e.g., LiNiYMnYO2 (where 0 <Y<1), LiMn2-zNizO4 (onde 0<Z<2), etc.), um óxido à base de lítioníquel-cobalto (por exemplo, LíNíi-yiCoyiO2 (onde 0<Y1<1), etc.), um óxido à base de lítio-manganês-cobalto (por exemplo, LiCo1-Y2MnY2O2 (onde 0<Y2<1), LiMn2-z1Coz1O4 (onde 0<Z1<2), etc.), um óxido à base de lítio-níquel-manganês-cobalto (por exemplo, Li(NipCoqMnr1)O2 (onde 0<p<1, 0<q<1, 0<r1<1, p+q+r1=1) ou Li(Nip1Coq1Mnr2)O4 (onde 0<p1 <2, 0<q1 <2, 0<r2<2, p1+q1+r2=2), etc.), or a lithium-nickel-cobalt-transition metal oxide (M) (e.g., Li(Nip2Coq2Mnr3MS2)O2 (where, M is selected from Al, Fe, V, Cr, Ti, Ta, Mg and Mo, p2, q2, r3 and s2 are each an atomic fraction of independent elements, 0 < p2 < 1, 0 <q2<1, 0<r3<1, 0<s2<1, p2+q2+r3+s2=1), etc.) e semelhantes, e entre eles, qualquer um ou dois ou mais compostos podem ser incluídos. Entre eles, com o objetivo de melhorar as características de capacidade e estabilidade de uma bateria, o óxido composto de metal de transição de lítio pode ser LiCoO2, LiMnO2, LiNiO2, um óxido de lítio-níquel-manganês-cobalto (por exemplo, Li(Ni0,6Mn0,2Co0,2)O2, Li(Ni0,5Mn0,3Co0,2)O2, Li(Ni0,7Mn0,15Co0,15)O2 ou Li(Ni0,8Mn0,1Co0,1)O2, etc.), ou um. Petition 870250086070, dated 09 / 23 / 2025, page 35 / 58 27 / 40 lithium cobalt nickel aluminum oxide (e.g., Li(NiO8CoO15AlO5)O2, etc.) and the like, and considering the notable improvement effects caused by controlling the type and content ratio of the constituent elements that form the lithium transition metal oxide compound, the lithium transition metal oxide compound may be Li(NiO6MnO2CoO2)O2, Li(NiO5MnO3CoO2)O2, Li(NiO7MnO15CoO15)O2 or Li(NiO8MnO1CoO2)O2 and the like, and among them, any one or a mixture of two or more of the same may be used.

[082] More specifically, the active material of the positive electrode is a lithium transition metal composite oxide and may contain 60 mol% or more of nickel, based on the total number of moles of transition metals included in the lithium transition metal composite oxide. Specifically, the active material of the positive electrode is a lithium transition metal composite oxide and the transition metal includes nickel and at least one selected from manganese, cobalt, and aluminum, and may include nickel in an amount of 60 mol% or more, specifically 60 mol% to 90 mol%, based on the total number of moles of transition metal. It is preferable when the lithium transition metal composite oxide using such a high nickel content is used together with the non-aqueous electrolyte described above, for the purpose of reducing gas-phase byproducts generated by structural collapse.

[083] In addition, the active material of the positive electrode may include a lithium composite transition metal oxide represented by the following Formula A. [Formula A] Li1+x(NiaCobMncMd)O2

[084] In Formula A, M is at least one selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B and Mo, and 1+x, a, b, c and d are, are, each, independent atomic fractions of the elements, 0 <x<0,2, 0,50<a<1, 0<b<0,25, 0<c<0,25, 0<d<0,1, a+b+c+d=1.

[085] Preferably, a, b, c and c can be 0.70 <a<0,95, 0,025<b<0,20, 0,025<c<0,20 e 0<d<0,05, respectivamente. Petition 870250086070, dated 09 / 23 / 2025, page 36 / 58 28 / 40

[086] Preferably, a, b, c and c can be 0.80 <a<0,95, 0,025<b<0,15, 0,025<c<0,15 e 0<d<0,05, respectivamente.

[087] Preferably, a, b, c and c can be 0.85 <a<0,90, 0,05<b<0,10, 0,05<c<0,10 e 0<d<0,03, respectivamente.

[088] The active material of the positive electrode may be included in an amount of 80% by weight to 99% by weight, preferably 92% by weight to 98.5% by weight in the active material layer of the positive electrode, provided that the active material of the positive electrode has sufficient capacity.

[089] The active material layer of the positive electrode may additionally include a binder and / or a conductive material along with the active material of the positive electrode described above.

[090] The binder is a component that assists in the cohesion of an active material, a conductive material and the like, and in the cohesion to a current collector and, specifically, may include at least one selected from polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, an ethylene-propylene-diene terpolymer (EPDM), a sulfonated EPDM, styrene-butadiene rubber and fluorine rubber and, preferably, may include polyvinylidene fluoride.

[091] The binder may be included in an amount of 1.0% by weight to 20% by weight, preferably 1.2% by weight to 10% by weight in the active material layer of the positive electrode in order to sufficiently ensure a cohesive force between components, such as the active material of the positive electrode.

[092] The conductive material may be used to assist and improve the conductivity of the secondary battery and is not particularly limited, provided it has conductivity without causing chemical changes. Specifically, the conductive material of the positive electrode may include at least one selected from graphite, such as natural graphite or artificial graphite; carbon black, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black and black Petition 870250086070, dated 09 / 23 / 2025, p. 37 / 58 29 / 40 thermal; conductive fiber, such as carbon fiber and metallic fiber; conductive tubes, such as carbon nanotubes; fluorocarbon; metallic powder, such as aluminum and nickel powder; conductive wires, such as zinc oxide and potassium titanate; conductive metallic oxide, such as titanium oxide; and polyphenylene derivatives and, preferably, the conductive material may include carbon black in terms of improving conductivity.

[093] The conductive material may be included in an amount of 1.0% by weight to 20% by weight, preferably 1.2% by weight to 10% by weight in the active material layer of the positive electrode in order to sufficiently ensure electrical conductivity.

[094] The active material layer of the positive electrode can have a thickness of 30 μm to 400 μm, preferably 40 μm to 110 μm.

[095] The positive electrode can be manufactured by coating the positive electrode current collector with a positive electrode paste including a positive electrode active material and selectively a binder, a conductive material and a solvent to form a positive electrode paste and then drying and laminating.

[096] The solvent for forming a positive electrode paste may include an organic solvent, such as N-methyl-2-pyrrolidone (NMP). The solid content of the positive electrode paste may be from 40% by weight to 90% by weight, specifically from 50% by weight to 80% by weight. (2) Negative Electrode

[097] The negative electrode faces the positive electrode.

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

[099] The negative electrode current collector is not particularly limited, provided it has high conductivity without causing adverse chemical changes in the battery. Specifically, copper, stainless steel, aluminum, nickel, titanium, baked carbon, copper or stainless steel whose surface is treated with carbon, nickel, Petition 870250086070, dated 09 / 23 / 2025, page 38 / 58 30 / 40 titanium, silver and similar materials, and an aluminum-cadmium alloy can be used as a negative electrode current collector.

[0100] The negative electrode current collector typically has a thickness of 3 to 500 μm.

[0101] Microscopic irregularities can be formed on the surface of the negative electrode collector to improve the adhesion of the active electrode material. For example, the negative electrode current collector can be used in various formats, such as a film, a sheet, a metal foil, a mesh, a porous body, a foam body, a non-woven fabric body, and the like.

[0102] The active electrode material layer may be arranged on at least one surface of the negative electrode current collector. Specifically, the active electrode material layer may be arranged on one or both surfaces of the negative electrode current collector.

[0103] The electrode active material layer may include an electrode active material.

[0104] The electrode active material is a substance capable of reversibly intercalating and deintercalating lithium and may include at least one selected from a carbon-based active material, a silicon-based active material and a lithium metal, specifically it may include at least one selected from a carbon-based active material and a silicon-based active material and, more specifically, it may include a silicon-based active material.

[0105] The carbon-based active material may include at least one selected from artificial graphite, natural graphite, hard carbon, soft carbon, carbon black, graphene and fibrous carbon, preferably at least one selected from artificial graphite and natural graphite.

[0106] The average particle diameter (D50) of the carbon-based active material may be in the range of 10 μm to 30 μm, and preferably 15 μm to 25 μm in terms of ensuring structural stability during loading and unloading and reducing side reactions with an electrolyte. Petition 870250086070, dated 09 / 23 / 2025, pp. 39 / 58 31 / 40

[0107] The silicon-based active material may include at least one selected from a compound represented by SiOx (0 <x<2) e um compósito de silício-carbono. No caso do SiO2, já que o lítio não pode ser armazenado porque não reage com íons de lítio, e x está preferencialmente dentro da faixa acima. Mais preferencialmente, o material ativo à base de silício pode ser SiO.

[0108] When silicon-based active material is used as a negative electrode active material, a flexible and enhanced durability SEI layer can be formed on the negative electrode surface by the non-aqueous electrolyte described above, thus avoiding damage to the SEI layer due to volume expansion of the silicon-based active material, as well as avoiding an increase in SEI layer thickness and electrolyte consumption caused by exposure of a new silicon-based active material surface due to volume expansion, which is highly desirable.

[0109] The average particle size (D50) of the silicon-based active material can be from 1 ^ to 30 ^, preferably from 2 ^ to 15 ^ in terms of ensuring structural stability during loading and unloading and reducing side reactions with an electrolyte.

[0110] The active electrode material may be included in an amount of 60% by weight to 99% by weight, specifically 75% by weight to 95% by weight in the active electrode material layer.

[0111] The active electrode material layer may additionally include a binder and / or a conductive material along with the active electrode material described above.

[0112] The binder is used to improve battery performance by enhancing adhesion between the active electrode material layer and the negative electrode current collector; for example, it may include at least one selected from a copolymer of polyvinylidene fluoride-hexafluoropropylene (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, Petition 870250086070, dated 09 / 23 / 2025, pp. 40 / 58 32 / 40 polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, an ethylene-propylene-diene monomer (EPDM), a sulfonated EPDM, styrene-butadiene rubber (SBR), fluorinated rubber and a material in which hydrogen is replaced by Li, Na or Ca, and may also include various copolymers thereof.

[0113] The binder may be included in an amount of 0.5% by weight to 10% by weight, specifically 1.0% by weight to 5.0% by weight in the active material layer of the negative electrode.

[0114] Any conductive material may be used without specific limitation, provided it has conductivity without causing adverse chemical changes in the battery and, for example, a conductive material such as: graphite, such as natural graphite or artificial graphite; carbon black, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black and thermal black; conductive fibers, such as carbon fibers or metallic fibers; conductive tubes, such as carbon nanotubes; fluorocarbon; metallic powder, such as aluminum and nickel powder; conductive wires, such as zinc oxide and potassium titanate; conductive metallic oxide, such as titanium oxide; polyphenylene derivatives and the like, may be used.

[0115] The conductive material may be included in an amount of 0.5% by weight to 10% by weight, specifically 1.0% by weight to 5.0% by weight in the active material layer of the negative electrode.

[0116] The active material layer of the negative electrode can have a thickness of 10 μm to 100 μm, preferably 50 μm to 80 μm.

[0117] The negative electrode can be manufactured by coating the negative electrode current collector with a negative electrode paste including a negative electrode active material and selectively a binder, a conductive material and a solvent to form a negative electrode paste and then drying and laminating.

[0118] The solvent for forming a negative electrode paste may include, for example, at least one selected from distilled water, N-methyl-2-pyrrolidone (NMP), ethanol, methanol and isopropyl alcohol, preferably distilled water, in order to facilitate the dispersion of the active electrode material, the ligand and / or the Petition 870250086070, dated 09 / 23 / 2025, pp. 41 / 58 33 / 40 conductive material. The solid content of the negative electrode paste can be from 30% by weight to 80% by weight, and specifically, it can be from 40% by weight to 70% by weight. (3) Separator

[0119] In addition, as a separator, a commonly used porous polymer film, for example, a porous polymer film prepared with a polyolefin-based polymer, such as an ethylene homocopolymer, a propylene homocopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, can be used alone or in a laminated form. Alternatively, a typical porous nonwoven fabric, for example, a nonwoven fabric formed from a high-melting-point glass fiber or polyethylene terephthalate fiber, can be used, but the present disclosure is not limited to this. Furthermore, a coated separator including a ceramic component or a polymeric material can be used to ensure heat resistance or mechanical strength, and can be used selectively in a single-layer or multi-layer structure.

[0120] The shape of the secondary lithium battery of the present invention is not particularly limited, but a cylindrical type using a can, a prismatic type, a pouch type or a coin type may be used.

[0121] The present disclosure will now be described in detail, using examples. However, the invention can be embodied in many different forms and should not be interpreted as limited to the embodiments set forth in the present invention. Instead, these examples of embodiments are provided so that this description is complete and fully conveys the scope of the present disclosure to those skilled in the art. Examples and Comparative Examples Example 1 (Preparation of non-aqueous electrolyte) Petition 870250086070, dated 09 / 23 / 2025, pages 42 / 58 34 / 40

[0122] A mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) was used in a volume ratio of 30:70 as an organic solvent.

[0123] 0 LiPFe as a lithium salt and a compound represented by Formula 1-A-1 as an additive were added to the organic solvent to prepare a non-aqueous electrolyte.

[0124] LiPFe was included in the non-aqueous electrolyte at concentrations of 1.0 M.

[0125] The compound represented by Formula 1-A-1 was included in an amount of 3.0% by weight in the non-aqueous electrolyte. [Formula 1-A-1] (Preparation of the Secondary Battery)

[0126] A positive electrode active material (Li[NiO85CoO5MnO5AlO3]O2), a conductive material (carbon nanotube), and a ligand (polyvinylidene fluoride) were added to N-methyl-2-pyrrolidone (NMP) as solvent, in a weight ratio of 97.74:0.70:1.56 to prepare a positive electrode mixture paste (solids content: 75.5 wt%). The positive electrode mixture was applied to the surface of a positive electrode current collector (Al thin film) with a thickness of 12 µm, dried, and then roller-pressed to prepare a positive electrode.

[0127] A negative electrode active material (natural graphite): a conductive material (carbon black): a binder (styrene-butadiene rubber (SBR) carboxymethylcellulose (CMC)) were added in a weight ratio of Petition 870250086070, dated 09 / 23 / 2025, pages 43 / 58 35 / 40 96.15:1.55:2.30 to distilled water, which was a solvent, to prepare a negative electrode mixture paste (solids content 26% by weight). The negative electrode mixture was applied to the surface of a negative electrode current collector (thin Cu film) with a thickness of 15 μm, dried, and then roller-pressed to form a layer of active negative electrode material (thickness: 179.8 μm) and prepare a negative electrode.

[0128] In a dry room, a porous polyethylene polymer separator was interposed between the positive and negative electrodes prepared above, and then the prepared non-aqueous electrolyte was injected into it to prepare a secondary battery. Example 2

[0129] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1, except that 0.05% by weight of the compound represented by Formula 1-A-1 was added to the non-aqueous electrolyte instead of 3.0% by weight. Example 3

[0130] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1, except that 5.0% by weight of the compound represented by Formula 1-A-1 was added to the non-aqueous electrolyte instead of 3.0% by weight. Example 4

[0131] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1, except that 3.0% by weight of the compound represented by Formula 1-B-1 was added to the non-aqueous electrolyte instead of adding 3.0% by weight of the compound represented by Formula 1-A-1. [Formula 1-B-1] Petition 870250086070, dated 09 / 23 / 2025, pages 44 / 58 36 / 40 Example 5

[0132] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 4, except that 0.05% by weight of the compound represented by Formula 1-B-1 was added to the non-aqueous electrolyte instead of 3.0% by weight. Example 6

[0133] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 4, except that 5.0% by weight of the compound represented by Formula 1-B-1 was added to the non-aqueous electrolyte instead of 3.0% by weight. Comparative Example 1

[0134] A non-aqueous electrolyte and a secondary lithium battery were prepared in the same manner as in Example 1, except that the compound represented by Formula 1-A-1 was not added. Comparative Example 2

[0135] A non-aqueous electrolyte and a secondary lithium battery were prepared in the same manner as in Example 1, except that 3.0% by weight of the compound represented by Formula 3 below was added to the non-aqueous electrolyte instead of adding 3.0% by weight of the compound represented by Formula 1-A-1. [Formula 3] Petition 870250086070, dated 09 / 23 / 2025, pages 45 / 58 37 / 40 Comparative Example 3

[0136] A non-aqueous electrolyte and a lithium secondary battery were prepared in the same manner as in Example 1, except that 3.0% by weight of the compound represented by Formula 4 below was added to the non-aqueous electrolyte instead of adding 3.0% by weight of the compound represented by Formula 1-A-1.

[0137] [Formula 4] Comparative Example 4

[0138] A non-aqueous electrolyte and a secondary lithium battery were prepared in the same manner as in Example 1, except that 3.0% by weight of the compound represented by Formula 5 below was added to the non-aqueous electrolyte instead of adding 3.0% by weight of the compound represented by Formula 1-A-1. [Formula 5] Petition 870250086070, dated 09 / 23 / 2025, pp. 46 / 58 38 / 40 Experimental Examples

[0139] Experimental Example 1 Performance evaluation of the high-temperature cycle

[0140] The lithium secondary batteries prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were charged to 4.2 V with a current of 0.05 C at 45 °C using an electrochemical charger / discharger under DC / CV and 1 C conditions, and were then discharged to 3.0 V under DC, 0.5 C conditions, which was defined as one cycle. 200 charge / discharge cycles were performed. 1-1: Capacity Retention Rate Assessment

[0141] The capacity retention rate was calculated using the following equation, and the results are presented in the Table below.

[0142] Capacity retention rate (%) = (discharge capacity after 200 cycles / discharge capacity after 1 cycle) x 100 1-2: Evaluation of the rate of increase in resistance

[0143] After a charge and discharge cycle, the discharge capacity after one cycle was measured using an electrochemical charger / discharger, the SOC was set to 50% SOC and a 2.5C pulse was applied for 10 seconds. The initial resistance was calculated by the difference between the voltage before the pulse application and the voltage after the pulse application.

[0144] After 200 charge and discharge cycles, the resistance after 200 cycles was calculated in the same way as above. The rate of increase in resistance was calculated using the following equation, and the results are presented in Table 3 below.

[0145] Rate of increase in resistance (%) = {(resistance after 200 cycles - initial resistance) / initial resistance}x100 Experimental Example 2: Evaluation of high-temperature storage performance

[0146] The lithium secondary batteries prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were charged to 4.2 V with a current of 0.05 C at 25 °C under DC / CV conditions, 0.33 C, and were then discharged to 2.5 V at a Petition 870250086070, dated 09 / 23 / 2025, pp. 47 / 58 39 / 40 current of 0.33C to perform the initial charge / discharge. Subsequently, they were charged at 4.2 V with a current of 0.05 C under DC / CV conditions, 0.33 C at 25 °C, and then stored at 60 °C for 8 weeks. 2-1: Capacity Retention Rate Assessment

[0147] After 8 weeks of storage, the secondary lithium batteries were charged to 4.2 V with a current of 0.05 C at 25 °C under a condition of 0.33 C and were then discharged to 3.0 V at a current of 0.33 C. The capacity was then measured during discharge.

[0148] The capacity retention rate was evaluated using the following equation, and the results are presented in Table 1 below.

[0149] Capacity retention rate (%) = (discharge capacity after 8 weeks of storage / initial discharge capacity) x 100 2-2: Evaluation of the rate of increase in resistance

[0150] During initial charging and discharging, after capacity was confirmed at room temperature, secondary lithium batteries were charged to SOC 50 based on discharge capacity and discharged at a current of 3C for 10 seconds. Resistance was measured by voltage drop difference to obtain an initial resistance and was measured by the same method after storage at 60 °C for 8 weeks to obtain a final resistance. The rate of resistance increase was calculated using the following equation. The results are presented in Table 1 below.

[0151] Rate of increase in resistance (%) = (final resistance - initial resistance) / initial resistance) x 100 [Table 1] Experimental Example 1 Experimental Example 2 Capacity Retention Rate (%) Resistance Increase Rate (%) Capacity Retention Rate (%) Resistance Increase Rate (%) Example 1. 92 6 95 5 Example 2. 92 8 95 7 Example 3. 90 6 94 8 Petition 870250086070, dated 09 / 23 / 2025, pages 48 / 58 40 / 40 Example 4. 93 7 96 6 Example 5. 92 8 96 8 Example 6. 91 7 95 7 Comparative Example 1 76 34 72 38 Comparative Example 2 77 33 75 35 Comparative Example 3 77 33 74 36 Comparative Example 4 69 42 70 40

[0152] Referring to Table 1 above, it can be confirmed that the secondary lithium batteries of Examples 1 to 6, which used the non-aqueous electrolyte according to this disclosure, exhibited remarkably higher high-temperature capacity retention rates and lower resistance increase rates during high-temperature charge and discharge cycling and high-temperature storage, when compared to Comparative Examples 1 to 3, which did not use the non-aqueous electrolyte. Petition 870250086070, dated 09 / 23 / 2025, pp. 49 / 58

Claims

1 / 8 CLAIMS 1. Non-aqueous electrolyte, CHARACTERIZED in that it comprises: a lithium salt; an organic solvent; and an additive, wherein the additive includes a compound represented by Formula 1: [Formula 1] In Formula 1, Ri is an allyl group or a propargyl group, R2, Rs, R4 and Rs are each independently selected from hydrogen and an alkyl group with 1 to 5 carbon atoms, L is selected from a single bond and an alkylene group with 1 to 10 carbon atoms, and X is selected from -C(=O)-, -S(=O)- and -S(=O)2-.

2. Non-aqueous electrolyte, according to claim 1, CHARACTERIZED in that Ri is an allyl group.

3. Non-aqueous electrolyte, according to claim 1, CHARACTERIZED in that: X is selected from -C(=O)- and -S(=O)-.

4. Non-aqueous electrolyte, according to claim 1, CHARACTERIZED in that R2, Rs, R4 and Rs are each independently an alkyl group with 1 to 5 carbon atoms.

5. Non-aqueous electrolyte, according to claim 1, CHARACTERIZED in that the compound represented by Formula 1 includes at least one compound selected from the group consisting of compounds represented by Formula 1-A, Formula 1-B, Formula 1-C, Formula 2-A, Formula 2B and Formula 2-C: [Formula 1-A] [Formula 1-B] [Formula 1-C] [Formula 2-A] [Formula 2-B] 51 / 58 3 / 8 where, Formula 1-A, Formula 1-B, Formula 1-C, Formula 2-A, Formula 2B and Formula 2-C, R2, R3, R4 and Rs are as defined in Formula 1.

6. Non-aqueous electrolyte, according to claim 1, CHARACTERIZED in that the compound represented by Formula 1 includes at least one selected from the group consisting of compounds represented by Formula 1-A-1, Formula 1-A-2, Formula 1-B-1, Formula 1-B-2, Formula 1-C-1, Formula 1-C-2, Formula 2-A-1, Formula 2-A-2, Formula 2-B-1, Formula 2-B-2, Formula 2-C-1 and Formula 2-C-2 below: Petition 870250086070, dated 09 / 23 / 2025, p. 52 / 58 4 / 8 [Formula 1-B-2] [Formula 1-C-1] Petition 870250086070, dated 09 / 23 / 2025, p. 53 / 58 5 / 8 [Formula 2-A-1] Petition 870250086070, dated 09 / 23 / 2025, p. 54 / 58 6 / 8 [Formula 2-B-1] [Formula 2-C-2] Petition 870250086070, dated 09 / 23 / 2025, p. 55 / 58 7 / 8 7. Non-aqueous electrolyte, according to claim 1, CHARACTERIZED in that the compound represented by Formula 1 is included in an amount of 0.01% by weight to 10% by weight based on the weight of the non-aqueous electrolyte.

8. Non-aqueous electrolyte, according to claim 1, CHARACTERIZED in that the lithium salt includes at least one selected from the group consisting of LiCl, LiBr, LiI, L1BF4, L1CIO4, L1AIO4, LiAICk, LiPFe, LiSbFe, LiAsFe, LiB10Cl10, LiBOB(LiB(C2O4)2), LiCF3SO3, LiFSI(LiN(SO2F)2), LiCH3SO3, LiCF3CO2, LiCH3CO2 and LiBETI(LiN(SO2CF2CF3)2).

9. Non-aqueous electrolyte, according to claim 1, CHARACTERIZED in that the lithium salt is included in the non-aqueous electrolyte at a molar concentration of 0.5 M to 5.0 M.

10. Non-aqueous electrolyte, according to claim 1, CHARACTERIZED in that the organic solvent includes at least one selected from a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, a linear ester-based organic solvent, and a cyclic ester-based organic solvent.

11. Secondary lithium battery, CHARACTERIZED in that it comprises: a positive electrode; a negative electrode facing the positive electrode; a separator interposed between the positive and negative electrodes; and a non-aqueous electrolyte as defined in claim 1.