Rechargeable lithium battery

Abstract

The invention relates to a rechargeable lithium battery. A rechargeable lithium battery includes a positive electrode; a negative electrode; and an electrolyte solution, in which the positive electrode includes carbon nanotubes as a conductive material, and the electrolyte solution includes, as an additive, an imide cesium salt compound represented by Chemical Formula 1: Chemical Formula 1 # imgabs0 #

Description

Technical Field

[0001] One or more embodiments of the present disclosure relate to a rechargeable lithium battery. Background Art

[0002] Rechargeable lithium batteries are rechargeable and have an energy density per unit weight that is up to three or more times (i.e., at least three times more) that of 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 (e.g., charged to a relatively high energy density) and, therefore, are commercially used in the manufacture of laptop computers, cellular phones, power tools, electric bicycles, etc. And research has been actively conducted and / or sought to improve additional energy density.

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

[0004] One of the recent development directions of rechargeable lithium batteries is related to the storage characteristics of rechargeable lithium batteries in a wide temperature range (especially at high temperatures). However, when rechargeable lithium batteries are stored at high temperatures, the electrolyte decomposes and generates gas inside the battery, and due to the decrease in the amount and / or quality of the electrolyte, the wettability of the positive electrode decreases, causing the internal resistance of the battery to increase. Summary of the invention

[0005] One or more aspects of embodiments of the present disclosure are directed to a rechargeable lithium battery having improved storage characteristics at high temperatures.

[0006] Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the presented embodiments of the disclosure.

[0007] According to one or more embodiments of the present disclosure, a rechargeable lithium battery includes: a positive electrode; a negative electrode; and an electrolyte, wherein the positive electrode includes carbon nanotubes as a conductive material, and the electrolyte includes an imide cesium salt compound represented by Chemical Formula 1 as an additive:

[0008] Chemical formula 1

[0009]

[0010] One or more embodiments of the present disclosure may improve storage characteristics of a rechargeable lithium battery at high temperatures, and more effectively suppress or reduce initial resistance and resistance increase during high-temperature storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate example embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure. In the drawings:

[0012] Figure 1 A schematic diagram illustrating a rechargeable lithium battery according to one or more embodiments of the present disclosure.

[0013] Reference numerals

[0014] 100: Rechargeable lithium battery

[0015] 112: Negative electrode

[0016] 113: Diaphragm

[0017] 114: Positive electrode

[0018] 120: Battery housing

[0019] 140: Sealing member DETAILED DESCRIPTION

[0020] The present disclosure can be modified in many alternative forms, so specific embodiments will be illustrated in the drawings and described in more detail. However, it should be understood that this is not intended to limit the present disclosure to the specific form disclosed, but is intended to cover all modifications, equivalents and alternatives that fall within the spirit and scope of the present disclosure.

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

[0022] As utilized herein, when a specific definition is not otherwise provided, "substituted" may refer to the replacement of at least one hydrogen in a substituent or a compound by 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 one or more combinations thereof.

[0023] In one or more embodiments of the present disclosure, "substituted" may refer to at least one hydrogen in a substituent or compound being replaced 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 of the present disclosure, "substituted" may refer to at least one hydrogen in a substituent or compound being replaced by: deuterium, halogen, C1-C20 alkyl, C6-C30 aryl, C1-C10 fluoroalkyl or cyano. In some embodiments of the present disclosure, "substituted" may refer to at least one hydrogen in a substituent or compound being replaced by: deuterium, halogen, C1-C5 alkyl, C6-C18 aryl, C1-C5 fluoroalkyl or cyano. In some embodiments of the present disclosure, "substituted" may refer to at least one hydrogen in a substituent or compound being replaced by deuterium, cyano, halogen, methyl, ethyl, propyl, butyl, phenyl, biphenyl, terphenyl, trifluoromethyl or naphthyl.

[0024] According to the kind or type of separator and electrolyte used, rechargeable lithium battery can be classified into lithium ion battery, lithium ion polymer battery and lithium polymer battery. According to its shape, it can also be classified into cylindrical, prismatic, coin type or type, bag type or type, etc. In some embodiments, according to the size of the rechargeable lithium battery, it can be block type or type and thin film type or type. The structure and manufacturing method of the battery disclosed in the present invention are very suitable for this field.

[0025] Herein, as an example of a rechargeable lithium battery, for example, a cylindrical rechargeable lithium battery will be described in more detail. Figure 1 The structure of a rechargeable lithium battery according to one or more embodiments of the present disclosure is schematically shown. Figure 1 According to one or more embodiments, a rechargeable lithium battery 100 may include: 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 accommodating the battery cell; and a sealing member 140 sealing the battery case 120.

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

[0027] A rechargeable lithium battery according to one or more embodiments may include an electrolyte, a positive electrode, and a negative electrode.

[0028] The positive electrode may include carbon nanotubes as a conductive material (hereinafter referred to as “positive electrode conductive material” in some cases (embodiments)); and the electrolyte may include a cesium imide salt compound represented by Chemical Formula 1 as an additive (hereinafter, referred to as “electrolyte additive” in some cases (embodiments)):

[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] The electrolyte additive, namely the cesium imide salt compound represented by Chemical Formula 1, can be reduced and decomposed earlier than the carbonate-based solvent included in the non-aqueous organic solvent to form a stable SEI (solid electrolyte interface) film on the negative electrode. The stable SEI film formed in this way can prevent or reduce the decomposition of the electrolyte and the resulting electrode decomposition reaction, thereby improving the high-temperature storage characteristics of the rechargeable lithium battery.

[0033] On the other hand, the positive electrode conductive material, ie, carbon nanotubes (CNTs), can increase the wettability of the positive electrode compared to carbon black, a common positive electrode conductive material, thereby effectively suppressing or reducing the initial resistance of the rechargeable lithium battery and the resistance increase during high-temperature storage.

[0034] Therefore, one or more embodiments of the present disclosure are to combine an electrolyte additive that forms a stable SEI on the surface of a negative electrode to improve the high temperature storage characteristics of a rechargeable lithium battery with a positive electrode conductive material that increases the wettability of the positive electrode and suppresses the increase in initial resistance and resistance of the rechargeable lithium battery during high temperature storage.

[0035] Accordingly, not only the high-temperature storage characteristics of the rechargeable lithium battery can be improved, but also the initial resistance and the resistance increase during high-temperature storage can be effectively suppressed or reduced.

[0036] Hereinafter, the rechargeable lithium battery is explained in more detail.

[0037] The length of the carbon nanotubes may be about 10 μm to about 200 μm, about 10 μm to about 100 μm, about 30 μm to about 80 μm, or, for example, about 30 μm to about 50 μm.

[0038] The carbon nanotubes within the above length range can effectively increase the wettability of the positive electrode, and significantly suppress or reduce the initial resistance of the rechargeable lithium battery and the resistance increase during high-temperature storage.

[0039] However, if (for example, when) the length of the carbon nanotubes is too long, the movement of lithium ions may be hindered, and the initial resistance of the rechargeable lithium battery may increase. On the other hand, if (for example, when) the length of the carbon nanotubes is too short, the wettability of the positive electrode may be insufficient, and the resistance increase of the rechargeable lithium battery during high temperature storage may not be suppressed or reduced.

[0040] The positive electrode may include a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector; and the positive electrode conductive material (eg, carbon nanotubes) may be included in the positive electrode active material layer.

[0041] The positive electrode active material layer may include about 0.5 wt % to about 3 wt %, for example, about 0.5 wt % to about 2 wt % of the positive electrode conductive material, based on the total 100 wt % of the positive electrode active material layer.

[0042] The carbon nanotubes within the above content (eg, amount) range may effectively increase wettability of a positive electrode, and significantly suppress or reduce initial resistance and resistance increase during high-temperature storage of a rechargeable lithium battery.

[0043] However, if (e.g., when) the carbon nanotube content (e.g., amount) is too high, the movement of lithium ions may be hindered, thereby increasing the initial resistance of the rechargeable lithium battery. On the other hand, if (e.g., when) the carbon nanotube content (e.g., amount) is too low, the wettability of the positive electrode may be insufficient, and the resistance increase of the rechargeable lithium battery during high temperature storage may be suppressed or reduced.

[0044] In the present disclosure, the carbon nanotubes may be single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, or a mixture of two or more thereof. Wherein, when preparing a slurry including carbon nanotubes, the single-walled or double-walled type or species can improve dispersibility, and when forming a positive electrode active material layer, the resulting slurry can have excellent or appropriate processability, such as coating, and at the same time, excellent or appropriate conductivity of the formed positive electrode active material layer can be achieved.

[0045] In some embodiments, the positive electrode active material layer may further include an additional conductive material in addition to the carbon nanotubes. The additional conductive material may be contained in an amount of about 1.0 wt % to about 5.0 wt % based on 100 wt % of the total weight of the positive electrode active material layer.

[0046] An additional conductive material may be used to impart conductivity to the negative electrode, and any conductive material may be used as the conductive material unless it causes a chemical change in the battery. Non-limiting examples of conductive materials 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); or mixtures thereof.

[0047] The positive electrode active material layer may further include a positive electrode active material.

[0048] The positive electrode active material may include a lithiated intercalation compound that reversibly intercalates / deintercalates lithium ions. Non-limiting examples of the positive electrode active material may include a compound represented by any one of the following chemical formulas:

[0049] Li a A 1-b X b D2(0.90≤a≤1.8, 0≤b≤0.5);

[0050] Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05);

[0051] Li a E 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05);

[0052] Li a E 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05);

[0053] Li a Ni 1-b-c Co b X c D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α≤2);

[0054] Li a Ni 1-b-c Co b X c O 2-α Tα (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.05,0<α<2);

[0055] The a Nor 1-b-c Co b X c O 2-α T2(0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.05,0<α<2);

[0056] The a Nor 1-b-c Mn b X c D α (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.05<0<α≤2);

[0057] The a Nor 1-b-c Mn b X c O 2-α T α (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.05,0<α<2);

[0058] The a Nor 1-b-c Mn b X c O 2-α T2(0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.05,0<α<2);

[0059] The a Nor b E c G d O2(0.90≤a≤1.8,0≤b≤0.9,0≤c≤0.5,0.001≤d≤0.1);

[0060] The a Nor b Co c Mn d G e O2(0.90≤a≤1.8,0≤b≤0.9,0≤c≤0.5,0≤d≤0.5,0.001≤e≤0.1);

[0061] The a NiG b O2(0.90≤a≤1.8,0.001≤b≤0.1);

[0062] Thea CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1);

[0063] Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1);

[0064] Li a Mn b O4(0.90≤a≤1.8, 0.001≤b≤0.1);

[0065] Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5);

[0066] QO2; QS2; LiQS2;

[0067] V2O5; LiV2O5;

[0068] LiZO2;

[0069] LiNiVO4;

[0070] Li (3-f) J2(PO4)3(0≤f≤2);

[0071] Li (3-f) Fe2(PO4)3(0≤f≤2); and / or

[0072] Li a FePO4(0.90≤a≤1.8).

[0073] In the above chemical formula, A may be selected from nickel (Ni), cobalt (Co), manganese (Mn) and one or more combinations thereof; X may be selected from aluminum (Al), Ni, Co, Mn, chromium (Cr), iron (Fe), magnesium (Mg), strontium (Sr), vanadium (V), rare earth elements and one or more combinations thereof; D may be selected from oxygen (O), fluorine (F), sulfur (S), phosphorus (P) and one or more combinations thereof; E may be selected from Co, Mn and combinations thereof; T may be selected from F, S, P and one or more combinations thereof; G may be selected from Al, Cr, Mn, Fe, Mg, lanthanum (La), cerium (Ce), Sr, V and one or more combinations thereof; Q may be selected from titanium (Ti), molybdenum (Mo), Mn and one or more combinations thereof; Z may be selected from Cr, V, Fe, scandium (Sc), yttrium (Y) and one or more combinations thereof; and J may be selected from V, Cr, Mn, Co, Ni, copper (Cu) and one or more combinations thereof.

[0074] In one or more embodiments, the above-mentioned compound having a coating on its surface may be used, or a mixture of a compound and a compound having a coating may 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, and a basic carbonate of a coating element. The coating element compound for the coating may be amorphous or crystalline. The coating element included in the coating may be Mg, Al, Co, potassium (K), sodium (Na), calcium (Ca), silicon (Si), Ti, V, tin (Sn), germanium (Ge), gallium (Ga), boron (B), arsenic (As), zirconium (Zr), or a mixture thereof. The method for forming the coating may include a method that does not adversely affect the physical properties of the positive electrode active material, such as spraying or dipping.

[0075] For example, in one or more embodiments, the positive electrode active material may include lithium cobalt oxide.

[0076] 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 one or more embodiments of the present disclosure, by combining an electrolyte additive and a positive electrode conductive material, even when 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 suppressed or reduced.

[0077] In one or more embodiments, the positive electrode active material may include lithium cobalt oxide represented by Chemical Formula 2:

[0078] Chemical formula 2

[0079] Li a11 Co x11 M 11 y11 O2.

[0080] In Chemical Formula 2, 0.9≤a11≤1.8, 0.9≤x11≤1, 0≤y11≤0.1, x11+y11=1, and M 11 It can be selected from Al, B, Ce, Cr, F, Mg, Mn, Mo, niobium (Nb), P, S, Si, Sr, Ti, V, W, Zr and one or more combinations thereof.

[0081] For example, in some embodiments, the positive electrode active material may be LiCoO2.

[0082] In the positive electrode according to one or more 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 100 wt% of the total weight of the positive electrode active material layer.

[0083] The positive electrode active material layer may optionally include a binder. The content (eg, amount) of the binder may be about 1 wt% to about 5 wt% based on 100 wt% of the total weight of the positive electrode active material layer.

[0084] 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 non-limiting examples thereof may be 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 the embodiments of the present disclosure are not limited thereto.

[0085] The positive electrode current collector may include an Al foil, but embodiments of the present disclosure are not limited thereto.

[0086] The electrolyte additive may include a cesium imide salt compound represented by Chemical Formula 1.

[0087] In the cesium imide salt compound represented by Chemical Formula 1, the fluorine group directly connected to the sulfone forms a more stable SEI film (solid electrolyte interface) on the negative electrode, thereby preventing or reducing decomposition of the electrolyte and the resulting electrode decomposition reaction, thereby improving storage characteristics at high temperatures.

[0088] For example, in one or more embodiments, R 1 may be a fluoro group; and R 2 It may be a fluoro group or a C1-C3 perfluoroalkyl group.

[0089] Representative examples of the cesium imide salt compound can be given as follows:

[0090] Chemical formula 1-1

[0091]

[0092] Chemical formula 1-2

[0093]

[0094] Chemical formula 1-3

[0095]

[0096] Chemical formula 1-4

[0097]

[0098] Among the compounds exemplified above, in the cesium bis(fluorosulfonyl)imide (CsFSI: Cs + (FSO2)2N - ), the fluorine groups directly connected to the sulfone are (eg, simultaneously) present on both sides (eg, simultaneously present on two sulfone groups), and thus the effect of improving the storage characteristics at high temperatures can be better exhibited.

[0099] The electrolyte additive may be included in an amount of 0.1 wt % to 0.7 wt %, for example, 0.1 wt % to 0.5 wt %, based on the total 100 wt % of the electrolyte.

[0100] Within the above range, a rechargeable lithium battery having improved resistance characteristics when stored at high temperatures may be implemented.

[0101] The lithium salt dissolved in the non-aqueous organic solvent of the electrolyte supplies 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. Non-limiting examples of lithium salts may include those selected from LiPF6, LiBF4, lithium difluoro(bis(oxalato)phosphate (LiDFBOP), lithium difluoro(oxalato)borate (LiDFOB), LiPO2F2, LiSbF6, LiAsF6, LiN(SO3C2F5)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. When the lithium salt is included in the above concentration range, the electrolyte may have excellent or appropriate performance and lithium ion mobility due to optimal or appropriate electrolyte conductivity and viscosity.

[0102] The nonaqueous organic solvent serves as a medium for transmitting ions participating in the electrochemical reaction of the battery.

[0103] The non-aqueous organic solvent may include a carbonate solvent, an ester solvent, an ether solvent, a ketone solvent, an alcohol solvent or an aprotic solvent or a mixture thereof.

[0104] 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 non-limiting examples of aprotic solvents may 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.

[0105] The nonaqueous organic solvent may be used alone or in combination of two or more thereof, and when used in combination of two or more, the mixing ratio may be appropriately adjusted according to desired or appropriate battery performance, which is well known to those skilled in the art.

[0106] In some embodiments, the carbonate solvent may be prepared by mixing a cyclic carbonate and a linear carbonate. The cyclic carbonate and the linear carbonate are mixed together in a volume ratio of about 5:95 to about 50:50. When the mixture is used as a non-aqueous organic solvent for an electrolyte, it may have enhanced performance.

[0107] For example, in some embodiments, 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.

[0108] In one or more 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 some embodiments, the carbonate-based solvent in which ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) are mixed is mixed in a volume ratio of EC:EMC:DMC=about 1:0.5:5 to about 5:3:10, which can improve the performance of the electrolyte.

[0109] In one or more embodiments, 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.

[0110] The aromatic hydrocarbon solvent may be an aromatic hydrocarbon compound represented by Chemical Formula 3.

[0111] Chemical formula 3

[0112]

[0113] In chemical formula 3, R 201 To R 206 Each may be independently the same or different, and may be independently selected from hydrogen, halogen, C1-C10 alkyl, C1-C10 haloalkyl, and one or more combinations thereof.

[0114] Non-limiting 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, 2-fluorotoluene, and the like. ,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 one or more combinations thereof.

[0115] In one or more embodiments, the electrolyte may further include vinylene carbonate, vinyl ethylene carbonate, or an ethylene carbonate-based compound represented by Chemical Formula 4 as an additive for improving cycle life to improve the cycle life of the battery.

[0116] Chemical formula 4

[0117]

[0118] In chemical formula 4, R 207 and R 208 may be independently the same or different and may be independently selected from hydrogen, halogen, cyano (CN), nitro (NO2) and C1-C5 fluoroalkyl, provided that R 207 or R 208 At least one of them may be halogen, cyano (CN), nitro (NO2) and C1-C5 fluoroalkyl, and R 207 and R 208 Not simultaneously (eg, synchronously) hydrogen.

[0119] Non-limiting examples of ethylene carbonate compounds may include difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, or fluoroethylene carbonate. The amount of the additive for improving the cycle life may be used in an appropriate or appropriate range.

[0120] The negative electrode may include a negative electrode current collector and a negative electrode active material layer including a negative electrode active material on the negative electrode current collector.

[0121] The negative electrode active material may be a material that reversibly intercalates / deintercalates lithium ions, lithium metal, a lithium metal alloy, a material capable of doping / dedoping lithium, and / or a transition metal oxide.

[0122] The material that reversibly intercalates / deintercalates lithium ions may include a carbon material. The carbon material may be any commonly used carbon-based negative electrode active material in a rechargeable lithium battery. Non-limiting examples of carbon materials may include crystalline carbon, amorphous carbon, and combinations thereof. Crystalline carbon may be amorphous (e.g., irregularly shaped), or natural graphite or artificial graphite in the form of flakes, lamellae, spheres, or fibers. Amorphous carbon may be soft carbon, hard carbon, a product of carbonization of mesophase pitch, fired coke, etc.

[0123] The lithium metal alloy may include lithium and a metal selected from sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), silicon (Si), antimony (Sb), lead (Pb), indium (In), zinc (Zn), barium (Ba), radium (Ra), germanium (Ge), aluminum (Al) and tin (Sn).

[0124] 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 one or more combinations thereof), 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 one or more combinations thereof), etc. In some embodiments, at least one of them may be mixed with SiO2.

[0125] The elements Q and R may be independently selected from Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, hafnium (Hf), ruthenium (Rf), V, Nb, tantalum (Ta), thorium (Db), Cr, Mo, W, (Sg), technetium (Tc), rhenium (Re), (Bh), Fe, Pb, ruthenium (Ru), osmium (Os), (Hs), rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt), Cu, silver (Ag), gold (Au), Zn, cadmium (Cd), B, Al, Ga, Sn (R does not include Sn), In, thallium (Tl), Ge, P, As, Sb, bismuth (Bi), S, selenium (Se), tellurium (Te), polonium (Po) and one or more combinations thereof.

[0126] The transition metal oxide may be vanadium oxide, lithium vanadium oxide, or the like.

[0127] In one or more embodiments, the negative electrode active material may include at least one of graphite and a Si composite.

[0128] 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.

[0129] For example, in some embodiments, the Si—C composite in particle form may include a core including Si particles and amorphous carbon.

[0130] The central portion of the core including the Si particle may include a hole, and a radius of the central portion may correspond to about 30% to about 50% of the radius of the Si—C composite.

[0131] The Si particles may have an average particle diameter of about 10 nm to about 200 nm.

[0132] As utilized herein, the average particle size (D50) may be a particle size at which the volume ratio is 50% in a cumulative size-distribution curve.

[0133] If (for example, when) the average particle size of the Si particles is within the above range, volume expansion occurring during charge and discharge can be suppressed or reduced, and disconnection of the conduction path due to particle crushing during charge and discharge can be prevented or reduced.

[0134] 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.

[0135] The central portion of the Si-C composite may not include (eg, may exclude) amorphous carbon. The amorphous carbon may exist only on the surface portion of the negative electrode active material (eg, on the surface portion of the Si-C composite).

[0136] 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.

[0137] In some embodiments, the Si particles are included substantially uniformly throughout the negative electrode active material, ie, are present in a substantially uniform concentration in the central portion and the surface portion thereof.

[0138] The amorphous carbon may be soft carbon, hard carbon, a product of carbonization of mesophase pitch, calcined coke, or one or more combinations thereof.

[0139] In one or more embodiments, the negative electrode active material may further include crystalline carbon.

[0140] If (for example, when) the negative electrode active material includes Si-C composite and crystalline carbon together, the Si-C composite and crystalline carbon may be included in the form of a mixture thereof, and in these embodiments, the Si-C composite and crystalline carbon may be included in a weight ratio of about 1:99 to about 50:50. In some embodiments, the Si-C composite and 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.

[0141] The crystalline carbon may be, for example, graphite, and, for example, natural graphite, artificial graphite, or a mixture thereof.

[0142] The crystalline carbon may have an average particle size of about 5 μm to about 30 μm.

[0143] The amorphous carbon precursor may include coal-based pitch, mesophase pitch, petroleum-based pitch, coal-based oil, petroleum-based heavy oil, or a polymer resin such as a phenol resin, a furan resin, or a polyimide resin.

[0144] 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 100 wt % of the total weight of the negative electrode active material layer.

[0145] In one or more embodiments, the negative electrode active material layer may include a binder and, optionally, a conductive material. In the negative electrode active material layer, the amount of the binder may be about 1wt% to about 5wt% based on the total weight of 100wt% of the negative electrode active material layer. If (for example, when) the negative electrode active material layer further includes a conductive material, the negative electrode active material layer may include about 90wt% to about 98wt% of the negative electrode active material, about 1wt% to about 5wt% of the binder and about 1wt% to about 5wt% of the conductive material.

[0146] The binder improves the bonding 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 a water-insoluble binder, a water-soluble binder, or a combination thereof.

[0147] The non-water-soluble binder may be polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide or one or more combinations thereof.

[0148] The water-soluble binder can be a rubber-based binder and / or a 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 one or more combinations thereof. The polymer resin binder can be selected from polytetrafluoroethylene, ethylene-propylene copolymer, polyethylene oxide, polyvinyl pyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, ethylene propylene diene copolymer, polyvinyl pyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol and one or more combinations thereof.

[0149] If (for example, when) 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 may include one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and alkali metal salts thereof. The alkali metal may be Na, K, or Li. Based on 100 wt % of the negative electrode active material, the amount of such a thickener included may be about 0.1 wt % to about 3 wt %.

[0150] A conductive material may be included to provide electrode conductivity, and any conductive material may be used as the conductive material unless it causes a chemical change. Non-limiting examples thereof may be 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 one or more mixtures (and / or combinations) thereof.

[0151] 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 one or more combinations thereof.

[0152] 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 a porous substrate, or may be a composite porous substrate.

[0153] The porous substrate may be a substrate including pores, and lithium ions may move through the pores. The porous substrate may be, for example, 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.

[0154] 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, in some embodiments, the heat-resistant layer may include a heat-resistant resin and optionally include a filler.

[0155] In some embodiments, the adhesive layer may include an adhesive resin, and optionally a filler.

[0156] The filler may be an organic filler and / or an inorganic filler.

[0157] refer to Figure 1 According to one or more embodiments, a rechargeable lithium battery 100 may include: a battery cell including a negative electrode 112, a positive electrode 114 facing the negative electrode 112, a separator 113 disposed 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.

[0158] 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.

[0159] Preparation of electrolyte

[0160] Preparation Example 1

[0161] A non-aqueous organic solvent was prepared by mixing ethylene carbonate:propylene carbonate:propyl propionate (EC:PC:PP) at a volume ratio of 10:15:75, 1.3 M LiPF6 was dissolved in the non-aqueous organic solvent, and 0.1 wt % of cesium bis(fluorosulfonyl)imide (CsFSI:Cs + (FSO2)2N - ) as an electrolyte additive to prepare the electrolyte.

[0162] The electrolyte additive was used in an amount of 0.1 wt % based on 100 wt % of the total electrolyte.

[0163] (Based on 100 wt% of the total electrolyte (lithium salt + non-aqueous organic solvent + additives), the "wt%" in the electrolyte composition refers to the relative weight of the additives)

[0164] Preparation Example 2

[0165] An electrolyte was prepared in substantially the same manner as in Preparation Example 1, except that the electrolyte additive was added in an amount of 0.2 wt %.

[0166] Preparation Example 3

[0167] An electrolyte was prepared in substantially the same manner as in Preparation Example 1, except that the electrolyte additive was added in an amount of 0.5 wt %.

[0168] Comparative Preparation Example 1

[0169] An electrolyte was prepared in substantially the same manner as in Preparation Example 1, except that no electrolyte additive was used.

[0170] Manufacturing of rechargeable lithium battery cells

[0171] Example 1

[0172] LiCoO2 as a positive electrode active material, polyvinylidene fluoride as a binder, and carbon nanotubes (length: 50 μm) 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.

[0173] 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.

[0174] 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, styrene-butadiene rubber as a binder, and carboxymethyl cellulose as a thickener were dispersed in distilled water in a weight ratio of 97:1:2 to prepare a negative electrode active material slurry.

[0175] The Si composite includes a core including artificial graphite and Si-containing particles, and coal pitch coated on the surface of the core.

[0176] 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.

[0177] 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 the electrolyte of Preparation Example 1.

[0178] Example 2

[0179] A rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 1, except that the electrolyte of Preparation Example 2 was used.

[0180] Example 3

[0181] A rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 1, except that the electrolyte of Preparation Example 3 was used.

[0182] Example 4

[0183] A rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 3, except that LiCoO2 as a positive electrode active material, polyvinylidene fluoride as a binder, and carbon nanotubes (length: 50 μm) as a conductive material were used in a weight ratio of 97.5:2:0.5 to manufacture the positive electrode.

[0184] Example 5

[0185] A rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 3, except that LiCoO2 as a positive electrode active material, polyvinylidene fluoride as a binder, and carbon nanotubes (length: 50 μm) as a conductive material were used in a weight ratio of 96:2:2 to manufacture the positive electrode.

[0186] Example 6

[0187] A rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 3, except that LiCoO2 as a positive electrode active material, polyvinylidene fluoride as a binder, and carbon nanotubes (length: 50 μm) as a conductive material were used in a weight ratio of 95:2:3 to manufacture the positive electrode.

[0188] Example 7

[0189] A rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 3, except that carbon nanotubes (length: 10 μm) were used as a conductive material to manufacture a positive electrode.

[0190] Example 8

[0191] A rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 3, except that carbon nanotubes (length: 30 μm) were used as a conductive material to manufacture a positive electrode.

[0192] Example 9

[0193] A rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 3, except that carbon nanotubes (length: 80 μm) were used as a conductive material to manufacture a positive electrode.

[0194] Example 10

[0195] A rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 3, except that carbon nanotubes (length: 100 μm) were used as a conductive material to manufacture a positive electrode.

[0196] Comparative Example 1

[0197] A rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 1, except that LiCoO2 as a positive electrode active material, polyvinylidene fluoride as a binder, and Ketjen black as a conductive material were used in a weight ratio of 97:2:1 to manufacture the positive electrode, and the electrolyte of Comparative Preparation Example 1 was used.

[0198] Comparative Example 2

[0199] A rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 1, except that LiCoO2 as a positive electrode active material, polyvinylidene fluoride as a binder, and Ketjen black as a conductive material were used in a weight ratio of 97:2:1 to manufacture the positive electrode, and the electrolyte of Preparation Example 3 was used.

[0200] Comparative Example 3

[0201] A rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 3, except that the electrolyte of Comparative Preparation Example 1 was used.

[0202] For reference, the main compositions of the additives in Examples and Comparative Examples are summarized in Table 1.

[0203] Table 1

[0204]

[0205] Evaluation 1: Evaluation of storage characteristics at high temperatures

[0206] The initial DC internal resistance (DC-IR) of the rechargeable lithium battery cells of Examples 1 to 10 and Comparative Examples 1 to 3 was measured individually by calculating ΔV / ΔI (voltage change / current change), and then, after their internal maximum energy state was changed to a fully charged state (SOC 100%) and stored at a high temperature of 60°C for 28 days, the DC resistance was remeasured and used to calculate the DC-IR increase rate (%) according to Equation 1, and the results are shown in Table 2.

[0207] Equation 1

[0208] DC-IR increase rate = ((DC-IR after 28 days - initial DC-IR) / initial DC-IR) * 100

[0209] Table 2

[0210]

[0211] Referring to Table 2, when the cesium imide salt compound represented by Chemical Formula 1 as an electrolyte additive and carbon nanotubes as a positive electrode conductive material are combined, the initial resistance (DC-IR) and the resistance increase rate after high-temperature storage (DC-IR increase rate) of the rechargeable lithium battery cell are significantly suppressed or reduced compared to when these two materials are not used at all or when either of these two materials is used alone.

[0212] In the present disclosure, it will be understood that the terms “comprise,” “include,” or “have / has” indicate the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0213] As used herein, "or" is not interpreted as an exclusive meaning, for example, "A or B" is interpreted as including A, B, A+B, etc. Further, as used herein, the term "and / or" includes any and all combinations of one or more related listed items. The " / " used herein may be interpreted as "and" or "or" depending on the circumstances. Expressions such as "at least one of...", "one of...", and "selected from...", when before / after a list of elements, modify the entire list of elements and do not modify a single element of the list. For example, "at least one of a, b, and c", "selected from at least one of a, b, and c", "selected from at least one of a to 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 a, b, and c, or variations thereof.

[0214] Throughout the present disclosure, when it is mentioned that a component such as a layer, film, region or plate is placed 'on' another component, it will be understood that it can be directly on the other component or another component can be interposed therebetween.

[0215] As utilized herein, the singular forms "a," "an," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, when describing embodiments of the present disclosure, the use of "may" refers to "one or more embodiments of the present disclosure."

[0216] In the present disclosure, when the particles are spherical, "diameter" indicates the particle size or average particle size, and when the particles are non-spherical, "diameter" indicates the major axis length or the average major axis length. The diameter of the particles can be measured using a scanning electron microscope or a particle size analyzer. As a particle size analyzer, for example, a HORIBA, LA-950 laser particle size analyzer can be used. When the size of the particles is measured using a particle size analyzer, the average particle size is referred to as D50. D50 refers to the average diameter of the particles whose cumulative volume corresponds to 50 vol% in a particle size distribution (e.g., cumulative distribution), and refers to a distribution curve accumulated in the order of the smallest particle size to the largest particle size, when the total number of particles is 100%, the value of the particle size corresponding to 50% starting from the smallest particle.

[0217] As utilized 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 would recognize. "About," as used herein, includes the recited value and means within an acceptable range of deviations 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 recited value.

[0218] 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.

[0219] Any suitable hardware, firmware (e.g., an application specific 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 particular computing device may be distributed on one or more other computing devices.

[0220] 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. A rechargeable lithium battery comprising Positive electrode; a negative electrode; and Electrolyte, wherein the positive electrode comprises carbon nanotubes as a conductive material, and The electrolyte includes a cesium imide salt compound represented by Chemical Formula 1 as an additive: Chemical formula 1 and in, In Chemical Formula 1, R 1 and R 2 Each independently is 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.

2. The rechargeable lithium battery of claim 1, wherein The length of the carbon nanotube is 10 μm to 200 μm.

3. The rechargeable lithium battery of claim 1, wherein The positive electrode comprises a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector; and The conductive material is in the positive electrode active material layer.

4. The rechargeable lithium battery of claim 3, wherein The conductive material is included at 0.5 wt % to 3 wt % based on the total 100 wt % of the positive electrode active material layer.

5. The rechargeable lithium battery of claim 3, wherein The positive electrode active material layer further includes a positive electrode active material; and The positive electrode active material includes lithium cobalt oxide.

6. The rechargeable lithium battery of claim 5, wherein The positive electrode active material includes lithium cobalt oxide represented by Chemical Formula 2: Chemical formula 2 Li a11 Co x11 M 11 y11 O2, and in, In chemical formula 2, 0.9≤a11≤1.8, 0.9≤x11≤1, 0≤y11≤0.1, x11+y11=1, and M 11 Selected from Al, B, Ce, Cr, F, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, Zr and one or more combinations thereof.

7. The rechargeable lithium battery of claim 3, wherein The positive electrode active material layer further includes a binder; and The binder includes 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 or one or more combinations thereof.

8. The rechargeable lithium battery of claim 1, wherein In Chemical Formula 1, R 1 is a fluorine group; and R 2 It is a fluoro group or a C1-C3 perfluoroalkyl group.

9. The rechargeable lithium battery of claim 8, wherein Chemical Formula 1 is any one selected from Chemical Formula 1-1 to Chemical Formula 1-4: Chemical formula 1-1 Chemical formula 1-2 Chemical formula 1-3 Chemical formula 1-4 10. The rechargeable lithium battery of claim 1, wherein The additive is included in an amount of 0.1 wt % to 0.7 wt % based on 100 wt % of the total electrolyte.

11. The rechargeable lithium battery of claim 1, wherein The electrolyte further comprises a non-aqueous organic solvent; and The non-aqueous organic solvent includes carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents and / or aprotic solvents.

12. The rechargeable lithium battery of claim 11, wherein The non-aqueous organic solvent includes carbonate solvents and ester solvents.

13. The rechargeable lithium battery of claim 12, wherein The carbonate-based solvent includes ethylene carbonate and propylene carbonate, and the ester-based solvent includes propyl propionate.

14. The rechargeable lithium battery of claim 1, wherein The electrolyte further comprises a lithium salt; and The lithium salt includes a salt selected from the group consisting of LiPF6, LiBF4, lithium difluoro(bisoxalate)phosphate, lithium difluoro(oxalate)borate, LiPO2F2, LiSbF6, LiAsF6, LiN(SO3C2F5)2, Li(FSO2)2N, LiC4F9SO3, LiClO4, LiAlO2, LiAlCl4, LiN(C p F 2p+ 1SO2)(C q F 2q+1 SO2), at least one of LiCl, LiI and LiB(C2O4)2, in, p and q are each independently an integer of 1-20.

15. The rechargeable lithium battery of claim 14, wherein The concentration of the lithium salt in the electrolyte is 1.0M to 2.0M.

16. The rechargeable lithium battery of claim 1, wherein The negative electrode includes a negative electrode active material layer including a negative electrode active material, and 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 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 x and at least one of Si alloys, wherein 0＜x≤2。 19. The rechargeable lithium battery of claim 16, wherein The negative electrode active material further includes crystalline carbon.

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