Electrolyte for rechargeable lithium battery and rechargeable lithium battery including same

Abstract

The present invention relates to an electrolyte for a rechargeable lithium battery and a rechargeable lithium battery including the same. An electrolyte for a rechargeable lithium battery includes a non-aqueous organic solvent, a lithium salt, and an additive, in which the additive includes a composition including a first compound and a second compound, the first compound being an imide cesium salt compound represented by Chemical Formula 1, and the second compound being a crown ether compound represented by Chemical Formula 2. Details of the chemical formula 1 and the chemical formula 2 are described in the specification.

Description

Technical Field

[0001] One or more aspects of embodiments of the present disclosure relate to an electrolyte for a rechargeable lithium battery and a rechargeable lithium battery including the electrolyte. Background Art

[0002] Rechargeable lithium batteries are rechargeable and have an energy density per unit weight that is three or more times (i.e., at least three times more) higher than similar lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, etc. Rechargeable lithium batteries can also be charged at a relatively high rate and, thus, can be commercially used in the manufacture of laptop computers, cellular phones, power tools, electric bicycles, etc. Research has been actively conducted and / or sought to further improve the additional energy density.

[0003] A rechargeable lithium battery may be manufactured by injecting an electrolyte into a battery cell including a positive electrode including a positive electrode active material capable of intercalating / deintercalating lithium ions and a negative electrode including a negative electrode active material capable of intercalating / deintercalating lithium ions.

[0004] One of the recent development directions of rechargeable lithium batteries is fast charging. However, if the rechargeable lithium battery is fast charged, lithium dendrites are precipitated on the surface of the negative electrode, and the cycle life characteristics of the rechargeable lithium battery may be deteriorated due to the precipitation on the negative electrode surface. Summary of the invention

[0005] One or more aspects of embodiments of the present disclosure are directed to an electrolyte for a rechargeable lithium battery that can improve fast charge performance and improve cycle-life characteristics even during fast charge.

[0006] One or more aspects of the disclosed embodiments are directed to a rechargeable lithium battery that can obtain improved cycle-life characteristics by applying an electrolyte even during rapid charging.

[0007] One or more embodiments provide an electrolyte for a rechargeable lithium battery and a rechargeable lithium battery including the electrolyte, the electrolyte including a nonaqueous organic solvent, a lithium salt, and an additive, wherein the additive includes a composition including a first compound and a second compound, the first compound being a cesium imide salt compound represented by Chemical Formula 1 and the second compound being a crown ether compound represented by Chemical Formula 2:

[0008] Chemical formula 1

[0009]

[0010] Chemical formula 2

[0011]

[0012] In some example embodiments, by combining a first compound that can improve the fast charging characteristics of a rechargeable lithium battery and a second compound that can increase the solubility of the first compound in a set or specific weight ratio, the fast charging performance of the rechargeable lithium battery can be further improved, and desired or appropriate cycle life characteristics can be ensured even during fast charging. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A schematic diagram illustrating a rechargeable lithium battery according to some example embodiments.

[0014] Description of Reference Numerals

[0015] 100: Rechargeable lithium battery

[0016] 112: Negative electrode

[0017] 113: Diaphragm

[0018] 114: Positive electrode

[0019] 120: Battery housing

[0020] 140: Sealing member DETAILED DESCRIPTION

[0021] Hereinafter, a rechargeable lithium battery according to some example embodiments will be described in more detail with reference to the accompanying drawings. However, these embodiments are examples, the present disclosure is not limited thereto, and the present disclosure is defined by the scope of the appended claims and their equivalents.

[0022] As utilized herein, when a specific definition is otherwise provided, "substituted" refers to the replacement of at least one hydrogen in a substituent or compound with deuterium, halogen, hydroxyl, amino, substituted or unsubstituted C1-C30 amine, nitro, substituted or unsubstituted C1-C40 silyl, C1-C30 alkyl, C1-C10 alkylsilyl, C6-C30 arylsilyl, C3-C30 cycloalkyl, C3-C30 heterocycloalkyl, C6-C30 aryl, C2-C30 heteroaryl, C1-C20 alkoxy, C1-C10 fluoroalkyl, cyano, or a combination thereof.

[0023] For example, "substituted" may refer to the replacement of at least one hydrogen in a substituent or compound by deuterium, halogen, C1-C30 alkyl, C1-C10 alkylsilyl, C6-C30 arylsilyl, C3-C30 cycloalkyl, C3-C30 heterocycloalkyl, C6-C30 aryl, C2-C30 heteroaryl, C1-C10 fluoroalkyl, or cyano. In some embodiments, "substituted" refers to the replacement of at least one hydrogen in a substituent or compound by deuterium, halogen, C1-C20 alkyl, C6-C30 aryl, C1-C10 fluoroalkyl, or cyano. In some embodiments, "substituted" refers to the replacement of at least one hydrogen in a substituent or compound by deuterium, halogen, C1-C5 alkyl, C6-C18 aryl, C1-C5 fluoroalkyl, or cyano. In some embodiments, "substituted" refers to replacement of at least one hydrogen in a substituent or compound with deuterium, cyano, halogen, methyl, ethyl, propyl, butyl, phenyl, biphenyl, terphenyl, trifluoromethyl, or naphthyl.

[0024] Depending on the type of separator and / or electrolyte, rechargeable lithium batteries can be classified as lithium ion batteries, lithium ion polymer batteries and / or lithium polymer batteries. Rechargeable lithium batteries can also be classified as cylindrical, prismatic, coin-shaped or similar, pouch-shaped or similar, etc. according to their shape. In some embodiments, rechargeable lithium batteries can be block-shaped or similar and / or thin-film-shaped or similar according to their size. Those of ordinary skill in the art should have a good understanding of the structure and manufacturing methods of batteries related to the present disclosure.

[0025] Herein, as an example of a rechargeable lithium battery, for example, a cylindrical rechargeable lithium battery is described. Figure 1 The structure of a rechargeable lithium battery according to one or more example embodiments is schematically shown. Figure 1 According to some example embodiments, a rechargeable lithium battery 100 includes: a battery cell including a positive electrode 114, a negative electrode 112 facing the positive electrode 114, a separator 113 between the positive electrode 114 and the negative electrode 112, and an electrolyte impregnating the positive electrode 114, the negative electrode 112, and the separator 113; a battery case 120 that accommodates the battery cell; and a sealing member 140 that seals the battery case 120.

[0026] Hereinafter, a more detailed configuration of the rechargeable lithium battery 100 according to some example embodiments will be described.

[0027] A rechargeable lithium battery according to some example embodiments includes an electrolyte, a positive electrode, and a negative electrode.

[0028] The electrolyte may include a non-aqueous organic solvent, a lithium salt, and an additive. The additive may be a composition including a first compound and a second compound, wherein the first compound is a cesium imide salt compound represented by Chemical Formula 1 and the second compound is a crown ether compound represented by Chemical Formula 2.

[0029] Chemical formula 1

[0030]

[0031] In Chemical Formula 1, R 1 and R 2 may be independently a fluoro group or a C1-C3 fluoroalkyl group substituted with at least one fluoro group; provided that R 1 and R 2 At least one of them is a fluorine group;

[0032] Chemical formula 2

[0033]

[0034] In Chemical Formula 2, Z may be O or NH; x and y may each independently be an integer of 0 or 1; and m and n may each independently be one of integers of 1 to 3.

[0035] The first compound, i.e., the cesium imide salt compound represented by Chemical Formula 1, can be reduced and decomposed earlier (e.g., faster) than a carbonate solvent included in a non-aqueous organic solvent, and thus can form a SEI (solid electrolyte interface) film on the negative electrode to prevent or reduce the decomposition of the electrolyte and the resulting electrode decomposition reaction, thereby improving the fast charging performance.

[0036] However, the first compound exists in the form of a salt and thus exhibits sharply or relatively deteriorated solubility at a set or specific concentration in the electrolyte, slightly deteriorating or reducing the effect of improving high temperature characteristics.

[0037] The second compound is a crown ether compound represented by Chemical Formula 2, and if used together with the first compound, can help improve the solubility of the first compound, thereby activating a mechanism (e.g., reaction) in which the first compound is reduced and decomposed to form a SEI film on the negative electrode, and thereby ensuring appropriate cycle life characteristics of the rechargeable lithium battery even during fast charging.

[0038] The composition of this embodiment includes the first compound and the second compound in a weight ratio of about 1:4 to about 1:10.

[0039] For example, if the amount of the second compound included is too small, below the above range (e.g., outside the above range), the first compound may not be properly dissolved, and if the amount of the second compound included is too large, above the above range (e.g., outside the above range), the amount of the first compound included may be quite (relatively) small, and thus may not properly or fully exhibit fast charging characteristics.

[0040] In some example embodiments, the composition may include the first compound and the second compound in a weight ratio of about 1:4 to about 1:10, about 1:4 to about 1:9, or about 1:4 to about 1:8. Within any of these ranges, the degree of improvement in fast charging characteristics may be maximized or increased due to the synergistic effect of the combination of the first compound and the second compound.

[0041] For example, by combining a first compound for improving the fast charging characteristics of a rechargeable lithium battery with a second compound for increasing the solubility of the first compound at a set or specific weight ratio, a more stable negative electrode SEI can be formed. Accordingly, even in the case of fast charging, the side reaction between the lithium ions embedded in the negative electrode and the electrolyte can be effectively or appropriately suppressed or reduced, thereby improving the fast charging performance of the rechargeable lithium battery and ensuring appropriate cycle life characteristics even during fast charging.

[0042] Hereinafter, the electrolyte for a rechargeable lithium battery will be described in more detail.

[0043] In the cesium imide salt compound represented by Chemical Formula 1 (hereinafter referred to as “first compound”), a fluorine group directly connected to sulfone forms a stable SEI film, and thus the effect of improving fast charge characteristics can be significantly improved.

[0044] For example, R 1 Can be a fluorine group; R 2 It may be a fluoro group, a C1 fluoroalkyl group substituted by three fluoro groups, a C2 fluoroalkyl group substituted by five fluoro groups, or a C3 fluoroalkyl group substituted by seven fluoro groups.

[0045] Representative examples of the first compound are as follows:

[0046] Chemical formula 1-1

[0047]

[0048] Chemical formula 1-2

[0049]

[0050] Chemical formula 1-3

[0051]

[0052] Chemical formula 1-4

[0053]

[0054] Among the compounds exemplified above, in the cesium bis(fluorosulfonyl)imide (CsFSI: Cs + (FSO2)2N - ), the fluorine groups directly connected to the sulfone are present on both sides (for example, on two sulfone groups), and thus the effect of improving the fast charging characteristics can be better exhibited (for example, the fast charging characteristics can be further improved).

[0055] In some embodiments, the second compound acts as a cation acceptor for the first compound and helps improve solubility.

[0056] In this regard, if the second compound has a structure containing at least five ether groups, the solubility of the first compound can be more effectively or appropriately improved. If the second compound includes less than five ether groups, the solubility of the first compound cannot be effectively or appropriately improved, so the desired fast charging improvement cannot be achieved.

[0057] For example, the second compound may be a crown ether compound represented by any one of Chemical Formula 2-1 to Chemical Formula 2-3:

[0058] Chemical formula 2-1

[0059]

[0060] Chemical formula 2-2

[0061]

[0062] Chemical formula 2-3

[0063]

[0064] In Chemical Formula 2-1 to Chemical Formula 2-3, m and n may each independently be an integer of 1 to 3.

[0065] For example, the second compound may be at least one selected from 15-crown-5, 18-crown-6, 21-crown-7, 24-crown-8, dibenzo-15-crown-5, dibenzo-18-crown-6, dibenzo-21-crown-7, dibenzo-24-crown-8, 1-aza-15-crown-5, 1-aza-18-crown-6, 1-aza-21-crown-7 and 1-aza-24-crown-8.

[0066] Among the compounds exemplified above, in the case of 18-crown-6, where m and n in Chemical Formula 2-1 are 1 and 2, respectively, the size of the crown is suitable for capturing the cation of the first compound so that the first compound can be dissolved more effectively or appropriately.

[0067] In some embodiments, the first compound may be included in an amount of about 0.1 wt % to about 2.0 wt %, for example, about 0.5 wt % to about 2.0 wt %, about 0.5 wt % to about 1.5 wt %, about 0.7 wt % to about 2.0 wt %, or about 0.7 wt % to about 1.0 wt %, based on 100 wt % of the electrolyte for a rechargeable lithium battery.

[0068] In some embodiments, the second compound may be included in an amount of about 0.1 wt % to about 10 wt %, for example, about 0.1 wt % to about 8.0 wt %, about 0.5 wt % to about 8.0 wt %, about 1.0 wt % to about 8.0 wt %, about 2.8 wt % to about 8 wt %, or about 4.0 wt % to about 8.0 wt %, based on 100 wt % of the electrolyte for a rechargeable lithium battery.

[0069] The composition including the first compound and the second compound may be included in an amount of about 0.5 wt % to about 10 wt %, for example, about 1.0 wt % to about 10 wt %, about 2.0 wt % to about 10 wt %, or about 2.5 wt % to about 10 wt %, based on 100 wt % of the electrolyte for a rechargeable lithium battery.

[0070] In one or more embodiments, the composition includes a first compound and a second compound in a weight ratio of about 1:4 to about 1:10, and within the above range, based on 100 wt % of the electrolyte for a rechargeable lithium battery, the first compound may be included in an amount of about 0.7 wt % to about 2.0 wt %, and based on 100 wt % of the electrolyte for a rechargeable lithium battery, the second compound may be included in an amount of about 2.8 wt % to about 8 wt %.

[0071] In some embodiments, the composition may include a first compound and a second compound in a weight ratio of about 1:4 to about 1:10, and within the above range, based on 100 wt % of the electrolyte for a rechargeable lithium battery, the first compound may be included in an amount of about 0.7 wt % to about 1.0 wt %, and based on 100 wt % of the electrolyte for a rechargeable lithium battery, the second compound may be included in an amount of about 4 wt % to about 8 wt %.

[0072] If the content (eg, amount) of the composition and the content (eg, amount) of each component in the composition are within their respective above ranges, a rechargeable lithium battery having improved resistance characteristics when stored at high temperatures may be implemented.

[0073] The lithium salt dissolved in the non-aqueous organic solvent promotes the supply of lithium ions in the battery, ensures the basic operation of the rechargeable lithium battery, and improves the transport of lithium ions between the positive electrode and the negative electrode. Examples of lithium salts include those selected from LiPF6, LiBF4, LiDFOP, LiDFOB, LiPO2F2, LiSbF6, LiAsF6, LiN(SO2C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide: LiFSI), LiC4F9SO3, LiClO4, LiAlO2, LiAlCl4, LiN(C p F 2p+1 SO2)(C q F 2q+1 SO2) (wherein, p and q may each independently be an integer of 1 to 20), at least one of LiCl, LiI and LiB(C2O4)2 (lithium bis(oxalato)borate: LiBOB). The lithium salt may be used in a concentration range of about 0.1 M to about 2.0 M. If the lithium salt is included in the above concentration range, the electrolyte may have excellent or appropriate performance and / or lithium ion mobility due to optimal or appropriate electrolyte conductivity and viscosity.

[0074] The nonaqueous organic solvent serves as a medium for transmitting ions participating in the electrochemical reaction of the battery.

[0075] The non-aqueous organic solvent may include a carbonate solvent, an ester solvent, an ether solvent, a ketone solvent, an alcohol solvent and / or an aprotic solvent.

[0076] Carbonate solvents may include ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), ethyl methyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), etc. Ester solvents may include methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, decanoic acid lactone, mevalonate lactone, caprolactone, etc. Ether solvents may include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, etc. Ketone solvents may include cyclohexanone, etc. Alcohol solvents may include ethanol, isopropanol, etc., and examples of aprotic solvents include nitriles (such as R-CN (wherein R is a C2 to C20 linear, branched or cyclic hydrocarbon group, and may include a double bond, an aromatic ring or an ether bond)), amides (such as dimethylformamide), dioxolanes (such as 1,3-dioxolane), sulfolane, etc.

[0077] The nonaqueous organic solvent may be used alone or in combination with one or more thereof, and if used in combination with one or more thereof, the mixing ratio may be appropriately or suitably adjusted according to desired or appropriate battery performance, which is well known to those skilled in the art.

[0078] The carbonate solvent is prepared by mixing a cyclic carbonate and a chain carbonate. The cyclic carbonate and the chain carbonate are mixed together in a volume ratio of about 5:95 to about 50:50. If the mixture is used as an electrolyte, it can have enhanced performance.

[0079] For example, ethylene carbonate (EC) and propylene carbonate (PC) may be used as the cyclic carbonate, and propyl propionate (PP) may be used as the chain carbonate.

[0080] In some embodiments, the non-aqueous organic solvent may include a carbonate-based solvent in which ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) are mixed. For example, in the carbonate-based solvent, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) may be mixed in a volume ratio of EC:EMC:DMC=about 1:0.5:5 to about 5:3:10, which may further improve the performance of the electrolyte.

[0081] The non-aqueous organic solvent may further include an aromatic hydrocarbon solvent in addition to the carbonate-based solvent. The carbonate-based solvent and the aromatic hydrocarbon solvent may be mixed together in a volume ratio of about 1:1 to about 30:1.

[0082] The aromatic hydrocarbon solvent may be an aromatic hydrocarbon compound represented by Chemical Formula 3.

[0083] Chemical formula 3

[0084]

[0085] In chemical formula 3, R 201 ~R 206 Each may be independently the same or different, and may be selected from hydrogen, halogen, C1-C10 alkyl, C1-C10 haloalkyl, and combinations thereof.

[0086] Examples of aromatic hydrocarbon solvents may be selected from benzene, fluorobenzene, 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, 1,2,3-trifluorobenzene, 1,2,4-trifluorobenzene, chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, iodobenzene, 1,2-diiodobenzene, 1,3-diiodobenzene, 1,4-diiodobenzene, 1,2,3-triiodobenzene, 1,2,4-triiodobenzene, toluene, fluorotoluene, 2,3-difluorotoluene, 2,4-difluorotoluene, 2,5-difluorotoluene, 2,3,4-trifluorotoluene, 2,3,5-trifluorotoluene, chlorotoluene, 2,3-dichlorotoluene, 2,4-dichlorotoluene, 2,5-dichlorotoluene, 2,3,4-trichlorotoluene, 2,3,5-trichlorotoluene, iodotoluene, 2,3-diiodotoluene, 2,4-diiodotoluene, 2,5-diiodotoluene, 2,3,4-triiodotoluene, 2,3,5-triiodotoluene, xylene, and combinations thereof.

[0087] The electrolyte may further include vinylene carbonate, vinyl ethylene carbonate, and / or an ethylene carbonate-based compound represented by Chemical Formula 4 as an additive for improving cycle life to further improve the cycle life of the battery.

[0088] Chemical formula 4

[0089]

[0090] In chemical formula 4, R 207 and R 208 may be independently the same or different and may be selected from hydrogen, halogen, cyano (CN), nitro (NO2) and C1-C5 fluoroalkyl, provided that R 207 and R 208 At least one of is halogen, cyano (CN), nitro (NO2) or C1-C5 fluoroalkyl, and R 207 and R 208 Not simultaneously (eg, synchronously) hydrogen.

[0091] Examples of ethylene carbonate compounds may include difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, and fluoroethylene carbonate. The amount of the additive for improving the cycle life may be used in an appropriate amount or in an appropriate range.

[0092] Some example embodiments provide a rechargeable lithium battery including: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and an electrolyte according to the present embodiment.

[0093] The positive electrode includes a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector, and the positive electrode active material layer includes a positive electrode active material.

[0094] The positive electrode active material may include a lithiated intercalation compound that reversibly intercalates and deintercalates lithium ions.

[0095] For example, at least one composite oxide of lithium and a metal of cobalt, manganese, nickel, or a combination thereof may be used.

[0096] A composite oxide having a coating on its surface can be used, or a mixture of a composite oxide and a composite oxide having a coating can be used. The coating may include a coating element compound selected from an oxide of a coating element, a hydroxide of a coating element, an oxyhydroxide of a coating element, an oxycarbonate of a coating element, or a hydroxycarbonate of a coating element. The compound used for the coating may be amorphous or crystalline. The coating element included in the coating may be Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or a mixture thereof. The coating process may include any appropriate process as long as it does not cause any side effects (e.g., any significant side effects) to the characteristics of the positive electrode active material. For example, the coating process may be spraying, dipping, etc., which is well known to those skilled in the art, and therefore a detailed description thereof is not provided.

[0097] For example, the positive electrode active material may include lithium cobalt oxide.

[0098] Compared with other positive electrode active materials, lithium cobalt oxide has lower wettability and may impair the storage characteristics of a rechargeable lithium battery including the lithium cobalt oxide at high temperatures. However, in some example embodiments, by combining the electrolyte additive and the positive electrode conductive material of the present embodiment, even if lithium cobalt oxide is used as a positive electrode active material, the high temperature storage characteristics of the rechargeable lithium battery are improved, and the initial resistance and the resistance increase during high temperature storage can be more effectively or appropriately suppressed or reduced.

[0099] In some embodiments, the positive electrode active material may include lithium cobalt oxide represented by Chemical Formula 3:

[0100] Chemical formula 3

[0101] Li a11 Co x11 M 11 y11 O2.

[0102] In Chemical Formula 3, 0.9≤a11≤1.8, 0.9≤x11≤1, 0≤y11≤0.1, x11+y11=1, and M 11It is at least one of Al, B, Ce, Cr, F, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W and Zr.

[0103] For example, the positive electrode active material may be LiCoO2.

[0104] In the positive electrode according to some example embodiments, the content (e.g., amount) of the positive electrode active material may be about 50 wt % to about 99 wt %, about 60 wt % to about 99 wt %, about 70 wt % to about 99 wt %, about 80 wt % to about 99 wt %, or about 90 wt % to about 99 wt %, based on the total weight of the positive electrode active material layer.

[0105] In some exemplary embodiments of the present disclosure, the positive electrode active material layer may optionally include a conductive material and a binder. In this case, the content (eg, amount) of the conductive material and the binder may each independently be about 1.0 wt % to about 5.0 wt % based on the total weight of the positive electrode active material layer.

[0106] A conductive material is used to impart conductivity to the negative electrode, and any suitable conductive material may be used as the conductive material as long as it does not cause significant chemical changes in the battery. Examples of the conductive material may include carbon-based materials (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, etc.); metal-based materials (such as metal powders and / or metal fibers including copper, nickel, aluminum, silver, etc.); conductive polymers (such as polyphenylene derivatives); or mixtures thereof.

[0107] The binder improves the bonding properties between the positive electrode active material particles and between the positive electrode active material particles and the positive electrode current collector, and examples thereof may include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc., but are not limited thereto.

[0108] The positive electrode current collector may include Al foil, but is not limited thereto.

[0109] The negative electrode includes a negative electrode current collector and a negative electrode active material layer including a negative electrode active material on the negative electrode current collector.

[0110] The negative electrode active material may be a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, a lithium metal alloy, a material capable of doping / dedoping lithium, and / or a transition metal oxide.

[0111] The material capable of reversibly inserting / deinserting lithium ions may include a carbon material. The carbon material may be any suitable carbon-based negative electrode active material in a rechargeable lithium battery. Examples of carbon materials may include crystalline carbon, amorphous carbon, and combinations thereof. Crystalline carbon may be amorphous, or may be natural graphite and / or artificial graphite in the form of flakes, flaks, spheres, and / or fibers. Amorphous carbon may be soft carbon, hard carbon, a product of carbonization of mesophase pitch, fired coke, and the like.

[0112] The lithium metal alloy may include lithium and a metal selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0113] Materials that can be doped / dedoped with lithium may include Si, SiO x (0<x≤2), Si-Q alloy (wherein Q is selected from alkali metal, alkaline earth metal, 13th group element, 14th group element (except Si), 15th group element, 16th group element, transition metal, rare earth element and its combination), Sn, SnO2, Sn-R alloy (wherein R is alkali metal, alkaline earth metal, 13th group element, 14th group element (except Sn), 15th group element, 16th group element, transition element, rare earth element or its combination), etc. At least one of them can be mixed with SiO2.

[0114] Elements Q and R can be selected from Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn (R does not include Sn), In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po and combinations thereof.

[0115] The transition metal oxide may be vanadium oxide, lithium vanadium oxide, or the like.

[0116] In some example embodiments, the negative electrode active material may include at least one of graphite and a Si composite.

[0117] The Si composite may include a core including Si-containing particles and amorphous carbon, and for example, the Si-containing particles may include a Si-C composite, SiO x (0<x≤2) and at least one of Si alloy.

[0118] For example, the Si—C composite may include a core including Si particles and amorphous carbon.

[0119] The central portion of the core may include a hole, and a radius of the central portion may correspond to about 30% to about 50% of a radius of the Si—C composite.

[0120] The Si particles may have an average particle diameter of about 10 nm to about 200 nm.

[0121] As used herein, the average particle size (D50) may be the particle size (e.g., the diameter of the particle) at which the volume ratio in the cumulative size-distribution curve is 50%. The average particle size D50 may be measured by an appropriate technique, for example, using a particle size analyzer, transmission electron microscopy, and / or scanning electron microscopy. Another method may be performed by the following process: using a measuring device with dynamic light scattering, analyzing data relative to each particle size to count a number of particles, and then calculating to obtain the average particle size D50. In this specification, when the particle is spherical, "diameter" indicates the particle size, and when the particle is non-spherical, "diameter" indicates the length of the major axis.

[0122] When the average particle diameter of the Si particles is within the above range, volume expansion occurring during charge and discharge can be suppressed or reduced, and disconnection of a conduction path due to particle crushing during charge and discharge can be prevented or reduced.

[0123] The Si particles may be included in an amount of about 1 wt % to about 60 wt %, for example, about 3 wt % to about 60 wt %, based on the total weight of the Si—C composite.

[0124] The central portion may not include (eg, may exclude) amorphous carbon, but amorphous carbon may exist on a surface portion (eg, only on the surface portion) of the negative electrode active material.

[0125] Herein, the surface portion indicates a region from the central portion of the negative electrode active material to the outermost surface of the negative electrode active material.

[0126] In some embodiments, the Si particles are substantially uniformly included on the negative electrode active material, for example, present in a substantially uniform concentration in a central portion and a surface portion thereof.

[0127] The amorphous carbon may be (eg, may include) soft carbon, hard carbon, a product of carbonization of mesophase pitch, calcined coke, or a combination thereof.

[0128] The negative electrode active material may further include crystalline carbon.

[0129] When the negative electrode active material includes the Si-C composite and the crystalline carbon together, the Si-C composite and the crystalline carbon may be included in the form of a mixture, and in this case, the Si-C composite and the crystalline carbon may be included in a weight ratio of about 1:99 to about 50:50. For example, the Si-C composite and the crystalline carbon may be included in a weight ratio of about 3:97 to about 20:80 or about 5:95 to about 20:80.

[0130] The crystalline carbon may be, for example, graphite, and may be natural graphite, artificial graphite, or a mixture thereof.

[0131] The crystalline carbon may have an average particle size of about 5 μm to about 30 μm.

[0132] The amorphous carbon precursor may include coal-based pitch, mesophase pitch, petroleum-based pitch, coal-based oil, petroleum-based heavy oil, and / or a polymer resin (such as a phenol resin, a furan resin, and / or a polyimide resin).

[0133] In the negative electrode active material layer, the negative electrode active material may be included in an amount of about 95 wt % to about 99 wt % based on the total weight of the negative electrode active material layer.

[0134] In some example embodiments, the negative electrode active material layer may include a binder and an optional conductive material. In the negative electrode active material layer, the amount of the binder may be about 1 wt% to about 5 wt% based on the total weight of the negative electrode active material layer. When the negative electrode active material layer further includes a conductive material, it may include about 90 wt% to about 98 wt% of the negative electrode active material, about 1 wt% to about 5 wt% of the binder, and about 1 wt% to about 5 wt% of the conductive material.

[0135] The binder improves the binding properties between the negative electrode active material particles and between the negative electrode active material particles and the negative electrode current collector. The binder may be (eg, may include) a non-water-soluble binder, a water-soluble binder, or a combination thereof.

[0136] The non-water-soluble binder may be (eg, may include) polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof.

[0137] The water-soluble binder can be (for example, can include) rubber-based binder and / or polymer resin binder. The rubber-based binder can be selected from styrene-butadiene rubber (SBR), acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber and combinations thereof. The polymer resin binder can be selected from polytetrafluoroethylene, ethylene-propylene copolymer, polyethylene oxide, polyvinyl pyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, ethylene-propylene copolymer, polyvinyl pyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol and combinations thereof.

[0138] If a water-soluble binder is used as a binder in the negative electrode active material layer, a cellulose compound may be further used as a thickener to provide viscosity. The cellulose compound includes one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and alkali metal salts thereof. The alkali metal may be Na, K, and / or Li. Based on 100 wt % of the negative electrode active material, the amount of the thickener included may be about 0.1 wt % to about 3 wt %.

[0139] A conductive material may be included to provide electrode conductivity, and any suitable conductive material may be used as the conductive material as long as it does not cause significant chemical changes in the battery. Examples thereof may include carbon-based materials (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, etc.); metal-based materials (such as metal powders or metal fibers including copper, nickel, aluminum, silver, etc.); conductive polymers (such as polyphenylene derivatives, etc.) or mixtures thereof.

[0140] The negative electrode current collector may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof.

[0141] According to the type or kind of the rechargeable lithium battery, the rechargeable lithium battery may further include a separator between the negative electrode and the positive electrode. The separator may be (eg, may include) a porous substrate; or it may be a composite porous substrate.

[0142] The porous substrate may be (for example, may include) a substrate including pores, and lithium ions may move through the pores. The porous substrate may be (for example, may include) a polyethylene separator, a polypropylene separator, a polyvinylidene fluoride separator, or a multilayer thereof, such as a polyethylene / polypropylene double-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, and / or a polypropylene / polyethylene / polypropylene three-layer separator.

[0143] The composite porous substrate may have a form including a porous substrate and a functional layer on the porous substrate. From the perspective of realizing additional functions, the functional layer may be, for example, at least one of a heat-resistant layer and an adhesive layer. For example, the heat-resistant layer may include a heat-resistant resin and an optional filler.

[0144] In some embodiments, the adhesive layer may include an adhesive resin and optionally a filler.

[0145] The filler may be an organic filler and / or an inorganic filler.

[0146] refer to Figure 1 According to some example embodiments, a rechargeable lithium battery 100 includes: a battery cell including a negative electrode 112, a positive electrode 114 facing the negative electrode 112, a separator 113 provided between the negative electrode 112 and the positive electrode 114, and an electrolyte impregnating the negative electrode 112, the positive electrode 114, and the separator 113; a battery case 120 accommodating the battery cell; and a sealing member 140 sealing the battery case 120.

[0147] Hereinafter, embodiments of the present disclosure and comparative examples will be described.The following embodiments are merely examples of the present disclosure, and the present disclosure is not limited to the following embodiments.

[0148] Preparation of electrolyte

[0149] Example 1

[0150] Ethylene carbonate:propylene carbonate:propyl propionate (EC:PC:PP) were mixed in a volume ratio of 10:15:75 to prepare a nonaqueous organic solvent, 1.3M LiPF6 was dissolved therein, and a composition including the first compound and the second compound in a weight ratio of 1:4 was added thereto.

[0151] For the first compound, cesium bis(fluorosulfonyl)imide (CsFSI: Cs + FSO 22 N - ), and for the second compound, 18-crown-6 was used.

[0152] The composition including the first compound and the second compound in a weight ratio of 1:4 was included in an amount of 3.5 wt % based on 100 wt % of the electrolyte for a rechargeable lithium battery.

[0153] (As used herein, in the electrolyte composition, "wt %" refers to the relative weight of the additive based on 100 wt % of the total electrolyte (lithium salt + non-aqueous organic solvent + additive).)

[0154] Example 2

[0155] An electrolyte was prepared in substantially the same manner as Example 1, except that an amount of the composition including the first compound and the second compound in a weight ratio of 1:4 was 5 wt % based on 100 wt % of the electrolyte for a rechargeable lithium battery.

[0156] Example 3

[0157] An electrolyte was prepared in substantially the same manner as Example 1, except that an amount of the composition including the first compound and the second compound in a weight ratio of 1:4 was 10 wt % based on 100 wt % of the electrolyte for a rechargeable lithium battery.

[0158] Example 4

[0159] An electrolyte was prepared in substantially the same manner as Example 1, except that an amount of the composition including the first compound and the second compound in a weight ratio of 1:8 was 9 wt % based on 100 wt % of the electrolyte for a rechargeable lithium battery.

[0160] Example 5

[0161] An electrolyte was prepared in substantially the same manner as Example 1, except that an amount of the composition including the first compound and the second compound in a weight ratio of 1:10 was 7.7 wt % based on 100 wt % of the electrolyte for a rechargeable lithium battery.

[0162] Comparative Example 1

[0163] An electrolytic solution was prepared in substantially the same manner as in Example 1, except that the first compound and the second compound were not used at all.

[0164] Comparative Example 2

[0165] An electrolyte was prepared in substantially the same manner as Example 1, except that the first compound was solely used in an amount of 0.5 wt % based on 100 wt % of the electrolyte for a rechargeable lithium battery.

[0166] Comparative Example 3

[0167] An electrolyte was prepared in substantially the same manner as Example 1, except that the first compound was solely used in an amount of 0.7 wt % based on 100 wt % of the electrolyte for a rechargeable lithium battery.

[0168] Comparative Example 4

[0169] An electrolyte was prepared in substantially the same manner as Example 1, except that the second compound was solely used in an amount of 5 wt % based on 100 wt % of the electrolyte for a rechargeable lithium battery.

[0170] Comparative Example 5

[0171] An electrolyte was prepared in substantially the same manner as Example 1, except that the second compound was solely used in an amount of 10 wt % based on 100 wt % of the electrolyte for a rechargeable lithium battery.

[0172] Comparative Example 6

[0173] An electrolyte was prepared in substantially the same manner as Example 1, except that an amount of the composition including the first compound and the second compound in a weight ratio of 1:2 was 2.1 wt % based on 100 wt % of the electrolyte for a rechargeable lithium battery.

[0174] Comparative Example 7

[0175] An electrolyte was prepared in substantially the same manner as Example 1, except that an amount of the composition including the first compound and the second compound in a weight ratio of 1:3 was 4 wt % based on 100 wt % of the electrolyte for a rechargeable lithium battery.

[0176] Comparative Example 8

[0177] An electrolyte was prepared in substantially the same manner as Example 1, except that an amount of the composition including the first compound and the second compound in a weight ratio of 1:15 was 11.2 wt % based on 100 wt % of the electrolyte for a rechargeable lithium battery.

[0178] Comparative Example 9

[0179] The electrolyte was prepared in substantially the same manner as in Example 1, except that cesium bis(trifluoromethanesulfonyl)imide (CsTFSI: Cs + (CF3SO2)2N - ) is used as the first compound.

[0180] For reference, each component of the additives in Examples and Comparative Examples is summarized in Table 1.

[0181] Table 1

[0182]

[0183] Evaluation 1: Evaluation of the dissolution of additives in the electrolyte

[0184] In each of the electrolyte solutions of Examples 1 to 5 and Comparative Examples 1 to 9, it was examined whether the additive was dissolved, and the results are shown in Table 2.

[0185] For example, after adding the first compound and the second compound to the alkaline electrolyte and stirring the obtained mixture for one day or more, the mixture is evaluated for whether there is a residue. If there is no residue, it is marked as O (dissolved), but if there is a residue, it is marked as X (undissolved).

[0186] Table 2

[0187] Dissolution of additives in electrolyte Example 1 O Example 2 O Example 3 O Example 4 O Example 5 O Comparative Example 1 (No additives) Comparative Example 2 O Comparative Example 3 X Comparative Example 4 O Comparative Example 5 X Comparative Example 6 X Comparative Example 7 X Comparative Example 8 X Comparative Example 9 X

[0188] Referring to Table 2, in Examples 1 to 5, the additives were all dissolved in the electrolyte, but in most of Comparative Examples 1 to 9, the additives were not all dissolved in the electrolyte.

[0189] For example, looking at Comparative Examples 2 to 5, if only the first compound or only the second compound is used, it should be used in an appropriately small amount to dissolve in the electrolyte. For example, Comparative Example 3, in which the additive is not completely dissolved, has a larger amount of the first compound than Comparative Example 2, in which the additive is dissolved. And Comparative Example 5, in which the additive is not completely dissolved, has a larger amount of the second compound than Comparative Example 4, in which the additive is dissolved.

[0190] Further, looking at Examples 1 to 5 and Comparative Examples 6 to 8, if the first compound and the second compound are combined and controlled or selected within a weight ratio range of 1:4 to 1:10, the additives are well dissolved in the electrolyte.

[0191] Assessment 2: Rapid Cycle Life Characteristics of Rechargeable Lithium Cells at Room Temperature

[0192] LiCoO 2 as a positive electrode active material, polyvinylidene fluoride as a binder, and Ketjen black as a conductive material were mixed at a weight ratio of 97:2:1, respectively, and then, dispersed in N-methylpyrrolidone to prepare a positive electrode active material slurry.

[0193] The positive electrode active material slurry was coated on a 15 μm thick Al foil, dried at 110° C., and pressed to produce a positive electrode.

[0194] A mixture of artificial graphite and Si composite in a weight ratio of 93:7 was prepared as a negative electrode active material, and the negative electrode active material in a weight ratio of 97:1:2, styrene-butadiene rubber as a binder, and carboxymethyl cellulose as a thickener were dispersed in distilled water to prepare a negative electrode active material slurry.

[0195] The Si composite includes a core including artificial graphite and Si-containing particles, and coal pitch coated on the surface of the core.

[0196] The negative electrode active material slurry was coated on a 10 μm thick Cu foil, dried at 100° C., and pressed to produce a negative electrode.

[0197] An electrode assembly was manufactured by assembling the manufactured positive and negative electrodes and a 25 μm thick polyethylene separator, and a rechargeable lithium battery cell was manufactured by injecting electrolytes of Examples 1 to 5 and Comparative Examples 1, 2, and 4, respectively.

[0198] The rapid cycle life characteristics at room temperature of each of the rechargeable lithium battery cells using the electrolytes of Examples 1 to 5 and Comparative Examples 1, 2, and 4 were evaluated, and the results are shown in Table 3.

[0199] For example, under the charging condition of CC-CV 3.0C / 4.5V and 1.0C cutoff and the discharging condition of CV 1.0C and 3.0V cutoff, the battery cell was charged and discharged 200 times in a constant temperature chamber at 25°C to measure the capacity retention rate.

[0200] Table 3

[0201]

[0202] Referring to Table 3, compared with Comparative Examples 1, 2, and 4, the rechargeable lithium battery cells of Examples 1 to 5 ensure appropriate or improved cycle life characteristics even during fast charging and improve fast charging performance by combining a first compound that improves fast charging characteristics and a second compound that increases the solubility of the first compound, especially in a set specific weight ratio.

[0203] In the present disclosure, "not including one or any 'component'", "excluding one or any 'component'", "no 'component'" and the like mean that the "component" is not added, selected or utilized as a component in the composition, but due to other impurities and / or external factors, the "component" may still be included in an appropriate amount.

[0204] In the present disclosure, when a particle is spherical, “diameter” indicates a particle diameter or an average particle diameter, and when a particle is non-spherical, “diameter” indicates a major axis length or an average major axis length.

[0205] Any suitable hardware, firmware (e.g., a dedicated integrated circuit), software, or a combination of software, firmware, and hardware may be used to implement a battery management system (BMS) device and / or any other related device or component according to an embodiment of the present invention described herein. For example, the various components of the device may be formed on an integrated circuit (IC) chip or on separate IC chips. Further, the various components of the device may be implemented on a flexible printed circuit film, a tape carrier package (TCP), a printed circuit board (PCB), or formed on a substrate. Further, the various components of the device may be processes or threads that run on one or more processors in one or more computing devices, execute computer program instructions, and interact with other system components to perform the various functions described herein. The computer program instructions are stored in a memory that may be implemented in a computing device using a standard memory device, such as, for example, a random access memory (RAM). The computer program instructions may also be stored in other non-temporary computer-readable media (such as, for example, a CD-ROM or a flash drive, etc.). Moreover, those skilled in the art should recognize that, without departing from the scope of the present disclosure, the functions of various computing devices may be combined or integrated into a single computing device, or the functions of a dedicated computing device may be distributed on one or more other computing devices.

[0206] It will be understood that although the terms first, second, etc. may be used to describe various elements in this article, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Therefore, without departing from the teachings of the present invention, the first element may be referred to as the second element. Similarly, the second element may be referred to as the first element.

[0207] As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0208] It will be further understood that the terms “includes,” “including,” “comprises” and / or “comprising,” when used in this specification, indicate the presence of stated features, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components and / or groups thereof.

[0209] As used herein, the terms "use," "using," and "used" may be considered synonyms of the terms "utilized," "utilizing," and "utilized," respectively.

[0210] As used herein, expressions such as "at least one of," "one of," and "selected from," when preceding / following a list of elements, modify the entire list of elements and do not modify the individual elements of the list. For example, "selected from at least one of a, b, and c" and "at least one of a, b, and c" may indicate only a, only b, only c, both a and b (e.g., simultaneously), both a and c (e.g., simultaneously), both b and c (e.g., simultaneously), all of a, b, and c, or variations thereof.

[0211] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0212] Further, when describing embodiments of the present disclosure, the use of “may” refers to “one or more embodiments of the present disclosure.”

[0213] It will be understood that when an element is referred to as being "on," "connected to," or "coupled to" another element, it can be directly on, connected to, or coupled to the other element, or one or more intervening elements may also be present. When an element is referred to as being "directly on," "directly connected to," or "directly coupled to" another element, there are no intervening elements.

[0214] For ease of description, spatially relative terms such as "below," "below," "below," "above," "on," "bottom," "top," and the like may be used herein to describe the relationship between one element or feature and another element or feature illustrated in the drawings. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the drawings. For example, if the device in the drawings is flipped, the elements described as "below" or "below" other elements or features are oriented "above" or "on" the other elements or features. Thus, the term "below" may encompass both the orientations of above and below. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.

[0215] As used herein, the terms "substantially," "about," and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent deviations in measured or calculated values ​​that one of ordinary skill in the art will recognize. "About" or "approximately" as used herein include the stated value and mean within an acceptable range of deviation determined by one of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system). For example, "about" may mean within one or more standard deviations, or within ±30%, ±20%, ±10%, or ±5% of the stated value.

[0216] Any numerical range set forth in this article is intended to include all subranges of the same numerical precision contained in the range set forth. For example, the range of "1.0-10.0" is intended to include all subranges (and end values) between the minimum value 1.0 set forth and the maximum value 10.0 set forth, that is, a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as, for example, 2.4-7.6. Any maximum numerical limit set forth herein is intended to include all lower numerical limits contained therein, and any minimum numerical limit set forth in this specification is intended to include all higher numerical limits contained therein. Accordingly, the applicant reserves the right to modify this specification (including claims) to explicitly set forth any subranges contained in the range explicitly set forth herein.

[0217] While the present disclosure has been described in conjunction with what are presently considered to be practical example embodiments, it is to be understood that the present disclosure is not limited to the disclosed embodiments, but, on the contrary, is intended to cover one or more suitable modifications and equivalent arrangements included within the spirit and scope of the appended claims and equivalents thereof.

Claims

1. An electrolyte for a rechargeable lithium battery, the electrolyte include: Non-aqueous organic solvents, Lithium salts, and additive, wherein the additive comprises a composition comprising a first compound and a second compound, The first compound is a cesium imide salt compound represented by Chemical Formula 1, The second compound is a crown ether compound represented by Chemical Formula 2, and The composition comprises the first compound and the second compound in a weight ratio of 1:4 to 1:10: Chemical formula 1 Wherein, in Chemical Formula 1, R 1 and R 2 Each is independently a fluoro group or a C1-C3 fluoroalkyl group substituted by at least one fluoro group; The condition is R 1 and R 2 At least one of them is a fluorine group; Chemical formula 2 and Wherein, in Chemical Formula 2, Z is O or NH, x and y are each independently an integer of 0 or 1, and m and n are each independently an integer of 1 to 3.

2. The electrolyte according to claim 1, wherein R 1 is a fluorine group; and R 2 It is a fluoro group, a C1 fluoroalkyl group substituted by three fluoro groups, a C2 fluoroalkyl group substituted by five fluoro groups, or a C3 fluoroalkyl group substituted by seven fluoro groups.

3. The electrolyte according to claim 1, wherein The first compound is represented by any one of Chemical Formulas 1-1 to 1-4: Chemical formula 1-1 Chemical formula 1-2 Chemical formula 1-3 Chemical formula 1-4 4. The electrolyte according to claim 1, wherein The second compound is represented by any one of Chemical Formula 2-1 to Chemical Formula 2-3: Chemical formula 2-1 Chemical formula 2-2 Chemical formula 2-3 and in, In Chemical Formula 2-1 to Chemical Formula 2-3, m and n are each independently an integer of 1 to 3.

5. The electrolyte according to claim 4, wherein The second compound is at least one of 15-crown-5, 18-crown-6, 21-crown-7, 24-crown-8, dibenzo-15-crown-5, dibenzo-18-crown-6, dibenzo-21-crown-7, dibenzo-24-crown-8, 1-aza-15-crown-5, 1-aza-18-crown-6, 1-aza-21-crown-7 and 1-aza-24-crown-8.

6. The electrolyte according to claim 1, wherein Based on 100 wt % of the electrolyte, an amount of the first compound is 0.1 wt % to 2.0 wt %.

7. The electrolyte according to claim 1, wherein Based on 100 wt % of the electrolyte, an amount of the second compound is 0.1 wt % to 10 wt %.

8. The electrolyte according to claim 1, wherein The composition including the first compound and the second compound is included in an amount of 0.5 wt % to 10 wt % based on 100 wt % of the electrolyte.

9. The electrolyte according to claim 1, wherein The non-aqueous organic solvent includes at least one of a carbonate solvent, an ester solvent, an ether solvent, a ketone solvent, an alcohol solvent and an aprotic solvent.

10. The electrolyte according to claim 9, wherein The non-aqueous organic solvent includes carbonate solvents and ester solvents.

11. The electrolyte according to claim 10, wherein The carbonate solvent includes ethylene carbonate and propylene carbonate, and The ester solvent includes propyl propionate.

12. The electrolyte of claim 1, wherein The lithium salt includes LiPF 6 , LiBF 4 、LiDFOP、LiDFOB、LiPO 2 F 2 、LiSbF 6 、LiAsF 6 、LiN(SO 3 C 2 F 5 ) 2 、Li(FSO 2 ) 2 N、LiC 4 F 9 SO 3 、LiClO 4 、LiAlO 2 、LiAlCl 4 、LiN(C p F 2p+1 SO 2 )(C q F 2q+1 SO 2 ), LiCl, LiI and LiB(C 2 O 4 ) 2 At least one of in, p and q are each independently an integer of 1-20.

13. The electrolyte of claim 12, wherein The concentration of the lithium salt in the electrolyte is in the range of 0.1M to 2.0M.

14. A rechargeable lithium battery, include: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and The electrolyte according to any one of claims 1 to 13.

15. The rechargeable lithium battery of claim 14, wherein The positive electrode active material is represented by Chemical Formula 3: Chemical formula 3 Li a11 Co x11 M 11 y11 O 2 ,and in, In chemical formula 3, 0.9≤a11≤1.8, 0.9≤x11≤1, 0≤y11≤0.1, x11+y11=1, M 11 It is at least one of Al, B, Ce, Cr, F, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W and Zr.

16. The rechargeable lithium battery of claim 14, wherein The negative electrode active material includes at least one of graphite and a Si composite.

17. The rechargeable lithium battery of claim 16, wherein The negative electrode active material includes the Si composite, and The Si composite includes a core including Si-containing particles and amorphous carbon.

18. The rechargeable lithium battery of claim 17, wherein The core comprising Si-containing particles comprises Si-C composite, SiO k and at least one of Si alloys, in, 0＜k≤2。 19. The rechargeable lithium battery of claim 18, wherein The Si—C composite includes a core including Si particles and amorphous carbon.

20. The rechargeable lithium battery of claim 16, wherein The negative electrode active material further includes crystalline carbon.

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