Rechargeable lithium battery

Abstract

The invention provides a rechargeable lithium battery. A rechargeable lithium battery includes: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and an electrolyte solution for a rechargeable lithium battery including a non-aqueous organic solvent, a lithium salt, and an additive, in which the additive includes a first compound represented by Chemical Formula 1 and a second compound represented by Chemical Formula 2, and the positive electrode active material includes a lithium nickel composite oxide represented by Chemical Formula 3.

Description

Technical Field

[0001] A rechargeable lithium battery is disclosed. Background Art

[0002] Recently, with the rapid popularization of electronic devices using batteries (such as mobile phones, notebook computers and electric vehicles), interest in rechargeable lithium batteries with high energy density and high capacity is rapidly increasing. Accordingly, research and development for improving the performance of rechargeable lithium batteries is actively being carried out.

[0003] The rechargeable lithium battery includes positive and negative electrodes including active materials capable of intercalating / deintercalating lithium ions and an electrolyte solution, and generates electric energy through oxidation and reduction reactions when lithium ions are intercalated / deintercalated at the positive and negative electrodes.

[0004] For example, since the characteristics of a rechargeable lithium battery are determined by complex reactions between a positive electrode and an electrolyte, and between a negative electrode and an electrolyte, using an appropriate or suitable electrolyte is one of the variables for improving the performance of a rechargeable lithium battery. Summary of the invention

[0005] Some embodiments of the present disclosure provide a rechargeable lithium battery that can improve charge / discharge characteristics when stored at high temperatures and cycle-life characteristics at room temperature and high temperatures while reducing the amount of generated gas at high temperatures.

[0006] A rechargeable lithium battery according to some embodiments includes: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and an electrolyte solution for a rechargeable lithium battery including a non-aqueous organic solvent, a lithium salt, and an additive, wherein the additive includes a first compound represented by Chemical Formula 1 and a second compound represented by Chemical Formula 2, and the positive electrode active material includes a lithium nickel composite oxide represented by Chemical Formula 3.

[0007] Chemical formula 1

[0008]

[0009] In Chemical Formula 1,

[0010] R 1 ~R 3 Each is independently hydrogen, cyano, halogen, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C2-C20 alkenyl, substituted or unsubstituted C2-C20 alkynyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C2-C20 heterocycloalkyl, substituted or unsubstituted C3-C20 cycloalkenyl, substituted or unsubstituted C6-C20 aryl, or substituted or unsubstituted C2-C20 heteroaryl;

[0011] Chemical formula 2

[0012]

[0013] Wherein, in Chemical Formula 2,

[0014] X 1 is a fluoro group (e.g., a fluorine atom), a chloro group (e.g., a chlorine atom), a bromo group (e.g., a bromine atom) or an iodo group (e.g., an iodine atom),

[0015] R 4 ~R 9 are each independently hydrogen, cyano, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxy, substituted or unsubstituted C2-C20 alkenyl, substituted or unsubstituted C2-C20 alkynyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C6-C20 aryl, or substituted or unsubstituted C2-C20 heteroaryl, and

[0016] n is an integer of 0 or 1;

[0017] Chemical formula 3

[0018] Li w Ni x Mn y M 1 1-x-y O 2

[0019] Among them, in chemical formula 3,

[0020] 0.5≤w≤1.8, 0.05≤x<1, 0<y≤0.7, and

[0021] M 1 It is Al, Fe, B, Ce, Cr, F, Mg, Mo, Nb, P, S, Si, Sr, Ti, V, W, Zr or a combination thereof.

[0022] A rechargeable lithium battery according to some embodiments may improve charge / discharge characteristics when stored at high temperature and cycle-life characteristics at room temperature and high temperature while reducing the amount of generated gas at high temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, together with the specification, illustrate embodiments of the presently disclosed subject matter, and, together with the description, serve to explain principles of embodiments of the presently disclosed subject matter.

[0024] Figure 1 is a schematic perspective view of a rechargeable lithium battery according to an embodiment.

[0025] Figure 2 is a schematic cross-sectional view of a rechargeable lithium battery according to an embodiment.

[0026] Figure 3-4 is a schematic perspective view of a rechargeable lithium battery according to an embodiment.

[0027] Description of Reference Numerals

[0028] 100: Rechargeable lithium battery 10: Positive electrode

[0029] 11: Positive lead lug 12: Positive terminal

[0030] 20: Negative electrode 21: Negative lead lug

[0031] 22: Negative terminal 30: Separator

[0032] 40: electrode assembly 50: shell

[0033] 60: Sealing member 70: Electrode terminal piece

[0034] 71: Positive electrode terminal tab 72: Negative electrode terminal tab DETAILED DESCRIPTION

[0035] Hereinafter, embodiments of the present disclosure will be described in more detail. However, these embodiments are presented as examples, and the present disclosure is not limited thereto, and the present disclosure is defined by the scope of the claims and their equivalents.

[0036] As used herein, when no specific limitations are provided otherwise, it will be understood that when an element (such as a layer, film, region, or substrate) is referred to as being "on" another element (such as a layer, film, region, or substrate), it can be directly on the other element (such as a layer, film, region, or substrate), or intervening elements may also be present.

[0037] Unless otherwise specified in the specification, a case indicated in the singular may also include the plural. Unless otherwise specified, "A or B" may mean "including A, including B, or including A and B".

[0038] As used herein, "combinations thereof" means mixtures, laminates, composites, copolymers, alloys, blends, reaction products, and the like, of the components.

[0039] As used herein, when no other definition is provided, the particle size may be the average particle size. In some embodiments, the particle size refers to the average particle size (D 50 ), which means the diameter of particles with a cumulative volume of 50% by volume in the particle size distribution. Average particle size (D 50) can be measured by any suitable method commonly used in the art (e.g., by a particle size analyzer, and / or by transmission electron microscope images and / or scanning electron microscope images). In some embodiments, a dynamic light scattering measurement device is used to perform data analysis, and the number of particles in each particle size range is counted. Thus, the average particle size (D) can be easily obtained by calculating 50 ) value. In some embodiments, the average particle size can be measured using a laser diffraction method. When measured by the laser diffraction method, for example, the particles to be measured can be dispersed in a dispersion medium and then introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), and ultrasonic waves of about 28 kHz are emitted at an output of 60 W to calculate the average particle size (D) based on 50% of the particle size distribution in the measuring device. 50 ).

[0040] As used herein, when no limitation is otherwise provided, "substituted" refers to the replacement of at least one hydrogen in a substituent or a compound by deuterium, halogen, hydroxyl, amino, C1-C30 amine, nitro, 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.

[0041] In some embodiments, "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. For example, "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, "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. For example, "substituted" may mean that at least one hydrogen in a substituent or compound is replaced by deuterium, cyano, halogen, methyl, ethyl, propyl, butyl, phenyl, biphenyl, terphenyl, trifluoromethyl, or naphthyl.

[0042] A rechargeable lithium battery according to some embodiments includes: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and an electrolyte solution for a rechargeable lithium battery including a non-aqueous organic solvent, a lithium salt, and an additive, wherein the additive includes a first compound represented by Chemical Formula 1 and a second compound represented by Chemical Formula 2, and the positive electrode active material includes a lithium nickel composite oxide represented by Chemical Formula 3.

[0043] Chemical formula 1

[0044]

[0045] In Chemical Formula 1,

[0046] R 1 ~R 3 Each is independently hydrogen, cyano, halogen, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C2-C20 alkenyl, substituted or unsubstituted C2-C20 alkynyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C2-C20 heterocycloalkyl, substituted or unsubstituted C3-C20 cycloalkenyl, substituted or unsubstituted C6-C20 aryl, or substituted or unsubstituted C2-C20 heteroaryl;

[0047] Chemical formula 2

[0048]

[0049] Wherein, in Chemical Formula 2,

[0050] X 1 is a fluoro group (e.g., a fluorine atom), a chloro group (e.g., a chlorine atom), a bromo group (e.g., a bromine atom) or an iodo group (e.g., an iodine atom),

[0051] R 4 ~R 9 are each independently hydrogen, cyano, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxy, substituted or unsubstituted C2-C20 alkenyl, substituted or unsubstituted C2-C20 alkynyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C6-C20 aryl, or substituted or unsubstituted C2-C20 heteroaryl, and

[0052] n is an integer of 0 or 1;

[0053] Chemical formula 3

[0054] Li w Ni x Mn y M 1 1-x-y O2

[0055] Among them, in chemical formula 3,

[0056] 0.5≤w≤1.8, 0.05≤x<1, 0<y≤0.7, and

[0057] M 1 It is Al, Fe, B, Ce, Cr, F, Mg, Mo, Nb, P, S, Si, Sr, Ti, V, W, Zr or a combination thereof.

[0058] The electrolyte solution includes a non-aqueous organic solvent, a lithium salt, and an additive.

[0059] The additive includes a first compound and a second compound.

[0060] The first compound is an isocyanurate compound, which can undergo a free radical reaction with other compounds having double bonds in the electrolyte solution to form a solid and low-resistance CEI (positive electrode electrolyte interface) film on the positive electrode, and can improve the charge / discharge characteristics of the battery when stored at high temperature and the cycle characteristics at room temperature and high temperature.

[0061] The first compound is represented by Chemical Formula 1.

[0062] Chemical formula 1

[0063]

[0064] In Chemical Formula 1, R 1 ~R 3 Each is independently hydrogen, cyano, halogen, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C2-C20 alkenyl, substituted or unsubstituted C2-C20 alkynyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C2-C20 heterocycloalkyl, substituted or unsubstituted C3-C20 cycloalkenyl, substituted or unsubstituted C6-C20 aryl or substituted or unsubstituted C2-C20 heteroaryl.

[0065] For example, R 1 ~R 3 They may each independently be a substituted or unsubstituted C1-C20 alkyl group or a substituted or unsubstituted C2-C20 alkenyl group.

[0066] As an example, R 1 ~R 3 Each independently may be a substituted or unsubstituted C2-C20 alkenyl group.

[0067] As an example, the first compound represented by Chemical Formula 1 may be any one or more selected from the compounds listed in Group 1.

[0068] Group 1

[0069]

[0070] As an example, the first compound may be triallyl isocyanurate, trimethyl isocyanurate, trimethylallyl isocyanate, or a combination thereof, but is not limited thereto.

[0071] The first compound may be included in an amount of about 0.05 wt % to about 3 wt % (e.g., about 0.1 wt % to about 2 wt % or about 0.5 wt % to about 1 wt %) based on the total weight of the electrolyte solution. Within the above range, a rechargeable lithium battery with improved high temperature storage characteristics and cycle life characteristics may be implemented.

[0072] The second compound forms an SEI (solid electrolyte interface) film having high temperature stability and excellent ion conductivity on the surface of the negative electrode, and suppresses or reduces the 2 LiPF due to F functional group 6 The side reaction of the electrolyte solution is reduced, thereby reducing the gas generation caused by the decomposition reaction of the electrolyte solution during high temperature storage.

[0073] In some embodiments, the second compound may be obtained by reacting with a thermal decomposition product of a lithium salt and / or a lithium salt such as LiPF 6 ) dissociated anions are coordinated to form complexes, and the formation of these complexes stabilizes the anions dissociated from the thermal decomposition products of the lithium salt and / or the lithium salt to inhibit or reduce the occurrence of unwanted side reactions, improve the cycle life characteristics of the rechargeable lithium battery, and significantly reduce the occurrence of defects by preventing or reducing gas generation inside the rechargeable lithium battery.

[0074] The second compound may be represented by Chemical Formula 2.

[0075] Chemical formula 2

[0076]

[0077] In chemical formula 2,

[0078] X 1 is a fluoro group (e.g., a fluorine atom), a chloro group (e.g., a chlorine atom), a bromo group (e.g., a bromine atom) or an iodo group (e.g., an iodine atom),

[0079] R 4 ~R 9are each independently hydrogen, cyano, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxy, substituted or unsubstituted C2-C20 alkenyl, substituted or unsubstituted C2-C20 alkynyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C6-C20 aryl, or substituted or unsubstituted C2-C20 heteroaryl, and

[0080] n is an integer of 0 or 1.

[0081] Chemical Formula 2 may include a compound represented by Chemical Formula 2A or Chemical Formula 2B.

[0082] Chemical formula 2A

[0083]

[0084] Chemical formula 2B

[0085]

[0086] In Chemical Formula 2A and Chemical Formula 2B,

[0087] X 1 is a fluoro group (e.g., a fluorine atom), a chloro group (e.g., a chlorine atom), a bromo group (e.g., a bromine atom) or an iodo group (e.g., an iodine atom), and

[0088] R 4 ~R 9 Each is independently hydrogen, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C1-C10 alkoxy, substituted or unsubstituted C2-C10 alkenyl or substituted or unsubstituted C2-C10 alkynyl.

[0089] In Chemical Formula 2A, R 6 and R 7 may each be hydrogen and be selected from R 8 and R 9 At least one of the may be a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C1-C10 alkoxy group, a substituted or unsubstituted C2-C10 alkenyl group, or a substituted or unsubstituted C2-C10 alkynyl group.

[0090] In Chemical Formula 2B, R 6 and R 7 may each be hydrogen and be selected from R 4 , R 5 , R 8 and R 9At least one of the may be a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C1-C10 alkoxy group, a substituted or unsubstituted C2-C10 alkenyl group, or a substituted or unsubstituted C2-C10 alkynyl group.

[0091] For example, in Formula 2A, R 6 and R 7 may each be hydrogen and be selected from R 8 and R 9 At least one of the groups may be a substituted or unsubstituted C1-C10 alkyl group.

[0092] As an example, the second compound represented by Chemical Formula 2 may be selected from the compounds listed in Group 2.

[0093] Group 2

[0094]

[0095] As an example, the second compound represented by Chemical Formula 2 may include 2-fluoro-1,3,2-dioxaphospholane, 2-fluoro-4-methyl-1,3,2-dioxaphospholane, or a combination thereof.

[0096] The second compound may be included in an amount of about 0.05 wt % to about 3 wt % (e.g., about 0.1 wt % to about 2 wt % or about 0.5 wt % to about 1 wt %) based on the total weight of the electrolyte solution. Within the above range, a rechargeable lithium battery with reduced gas generation when stored at high temperatures can be implemented.

[0097] In some embodiments, the additive may further include other additives in addition to the above-mentioned compounds.

[0098] The above-mentioned other additives may include vinylene carbonate (VC), fluoroethylene carbonate (FEC), difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, vinylethylene carbonate (VEC), adiponitrile (AN), succinonitrile (SN), 1,3,6-hexanetricyano (HTCN), propene sultone (PST), propane sultone (PS), lithium tetrafluoroborate (LiBF 4 ), lithium difluorophosphate (LiPO 2 F 2 ), 2-fluorobiphenyl (2-FBP), or a combination thereof.

[0099] By further including the above-mentioned other additives, the cycle life can be further improved, and / or the gas generated from the positive electrode and the negative electrode can be effectively controlled when stored at a high temperature.

[0100] The nonaqueous organic solvent serves as a medium for transmitting ions participating in the electrochemical reaction of the battery.

[0101] The non-aqueous organic solvent may include a carbonate solvent, an ester solvent, an ether solvent, a ketone solvent, an alcohol solvent, an aprotic solvent, or a combination thereof.

[0102] Carbonate solvents may include 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, dimethyl acetate, methyl propionate, ethyl propionate, decanoic acid lactone, mevalonolactone, valerolactone, caprolactone, etc.

[0103] Ether solvents may include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. In some embodiments, ketone solvents may include cyclohexanone, etc. Alcohol solvents may include ethanol, isopropanol, etc. and / or aprotic solvents may include nitrile (such as R-CN (wherein R is a C2 to C20 straight chain, branched or cyclic hydrocarbon group, and may include a double bond, an aromatic ring, an ether bond, etc.)); amides (such as dimethylformamide); dioxolanes (such as 1,3-dioxolanes, 1,4-dioxolanes, etc.); sulfolane, etc.

[0104] The nonaqueous organic solvents may be used alone or in combination of two or more.

[0105] In some embodiments, when a carbonate-based solvent is used, a cyclic carbonate and a chain carbonate may be mixed together and used, and the cyclic carbonate and the chain carbonate may be mixed together in a volume ratio of about 1:1 to about 1:9.

[0106] The lithium salt dissolved in the non-aqueous organic solvent 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. Examples of the lithium salt include those selected from LiPF 6 , LiBF 4 、LiSbF 6 、LiAsF 6 、LiClO 4 、LiAlO 2 、LiAlCl 4 、LiPO 2 F 2 、LiCl、LiI、LiN(SO 3 C 2 F 5 ) 2、Li(FSO 2 ) 2 N(lithium bis(fluorosulfonyl)imide, LiFSI), LiC 4 F 9 SO 3 、LiN(C x F 2x+1 SO 2 )(C y F 2y+1 SO 2 )(wherein x and y are integers of 1 to 20), at least one of lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalato)phosphate (LiDFOB) and lithium bis(oxalato)borate (LiBOB).

[0107] Positive electrode active material

[0108] The positive electrode active material may include a compound capable of intercalating / deintercalating lithium (lithiated intercalation compound). In some embodiments, at least one of a composite oxide of lithium and a metal selected from manganese, nickel, and a combination thereof may be used.

[0109] The composite oxide may be a lithium transition metal composite oxide, and examples include a cobalt-free lithium nickel manganese-based oxide, which is a lithium nickel composite oxide represented by Chemical Formula 3.

[0110] Chemical formula 3

[0111] Li w Ni x Mn y M 1 1-x-y O 2

[0112] In chemical formula 3,

[0113] 0.5≤w≤1.8, 0.05≤x<1, 0<y≤0.7, and

[0114] M 1 It is Al, Fe, B, Ce, Cr, F, Mg, Mo, Nb, P, S, Si, Sr, Ti, V, W, Zr or a combination thereof.

[0115] The lithium nickel composite oxide represented by Chemical Formula 3 is a so-called cobalt-free positive electrode active material, and in Chemical Formula 3, 0.5 ≤ w ≤ 1.8, 0.6 ≤ w ≤ 1.8, 0.7 ≤ w ≤ 1.8, 0.8 ≤ w ≤ 1.8, 0.9 ≤ w ≤ 1.8, 0.9 ≤ w ≤ 1.7, 0.9 ≤ w ≤ 1.6, 0.9 ≤ w ≤ 1.5, 0.9 ≤ w ≤ 1.4, 0.9 ≤ w ≤ 1.3, 0.9 ≤ w ≤ 1.2 or 0.9 ≤ w ≤ 1.1; 0.05 ≤ x < 1, 0.3 ≤ x < 1, 0.4 ≤ x < 1, 0.5 ≤ x < 1, 0.6 ≤ x < 1, 0.7 ≤ x < 1, 0.8 ≤ x < 1, or 0.9 ≤ x < 1; 0 < y ≤ 0.7, 0 < y ≤ 0.6, 0 < y ≤ 0.5, 0 < y ≤ 0.4, 0 < y ≤ 0.3, 0 < y ≤ 0.2 or 0 < y ≤ 0.1.

[0116] In the lithium nickel composite oxide represented by Chemical Formula 3, M in Chemical Formula 3 1 may further include at least one selected from B, Ce, Cr, F, Mg, Mo, Nb, P, S, Si, Sr, Ti, V, W, and Zr as an additional element. The additional element is a dopant and can improve the reversible insertion and extraction of lithium by partially modifying the lattice structure of each positive electrode active material.

[0117] The problem with the lithium nickel composite oxide represented by Chemical Formula 3 is that due to the increased Ni activity under high-voltage driving conditions, the decomposition of the electrolyte solution is promoted, and after a large amount of Ni is dissolved out, the surface of the negative electrode is reduced, thereby accelerating the deterioration of its cycle life. However, when used with the electrolyte solution including the above-mentioned first compound and second compound, the decomposition of the electrolyte solution can be suppressed or reduced, thereby reducing the amount of generated gas and improving the charge / discharge characteristics and cycle life characteristics of the battery.

[0118] In some embodiments, the lithium nickel composite oxide represented by Chemical Formula 3 can achieve relatively stable performance at a driving voltage of about 4.2 V or lower, but when the driving voltage is about 4.3 V or higher or, for example, about 4.35 V or higher, the side reaction between the lithium nickel composite oxide represented by Chemical Formula 3 and the electrolyte solution becomes severe, and transition metal ions are dissolved out, resulting in a rapid decline in battery performance, and the decline in battery performance can become more severe at high temperatures. However, when the lithium nickel composite oxide represented by Chemical Formula 3 is combined with the electrolyte solution including the above-mentioned first compound and second compound, stable battery performance can be achieved under high-voltage / high-temperature conditions.

[0119] In some embodiments, in addition to the cobalt-free lithium nickel manganese oxide, the positive electrode active material may further include a lithium nickel oxide, a lithium manganese oxide, a lithium iron phosphate compound, or a combination thereof.

[0120] As an example, the positive electrode active material may further include a compound represented by one selected from the following chemical formulae.

[0121] 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); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8,

[0122] 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a NeG b O 2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O 2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 2 G b O 4 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO 4 (0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe 2 (PO 4 ) 3 (0≤f≤2); or Li a FePO 4( 0.90≤a≤1.8).

[0123] In the above chemical formula, A is Ni, Mn or a combination thereof; X is Al, Ni, Mn, Cr, Fe, Mg, Sr, V, a rare earth element or a combination thereof; D is O, F, S, P or a combination thereof; and G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof.

[0124] For example, the positive electrode active material may be a high nickel-based positive electrode active material having a nickel content (based on 100 mol% of metals other than lithium in the lithium transition metal composite oxide) greater than or equal to about 80 mol%, greater than or equal to about 85 mol%, greater than or equal to about 90 mol%, greater than or equal to about 91 mol%, or greater than or equal to about 94 mol% and less than or equal to about 99 mol%. High nickel-based positive electrode active materials can achieve high capacity and can be applied to high capacity, high density rechargeable lithium batteries.

[0125] Positive electrode

[0126] The positive electrode for a rechargeable lithium battery may include a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector. The positive electrode active material layer may include a positive electrode active material and may further include a binder and / or a conductive material (eg, an electrically conductive material).

[0127] For example, the positive electrode may further include an additive that may function as a sacrificial positive electrode.

[0128] The amount of the positive electrode active material may be about 90 wt % to about 99 wt % based on 100 wt % of the positive electrode active material layer, and the amount of the binder and the conductive material may be about 0.5 wt % to about 5 wt % respectively based on 100 wt % of the positive electrode active material layer.

[0129] The binder is used to attach the positive electrode active material particles to each other well, and also to attach the positive electrode active material to the positive electrode current collector well. Examples of binders 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, (meth) acrylated styrene-butadiene rubber, epoxy resin, (meth) acrylic resin, polyester resin, nylon, etc., but are not limited thereto.

[0130] Conductive material Any suitable material that is used to impart conductivity (e.g., electrical conductivity) to the electrode and does not cause chemical changes (e.g., does not cause undesirable chemical changes in a rechargeable lithium battery) and conducts electrons can be used for 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, carbon nanofiber, and carbon nanotube; metal-based materials in the form of metal powder and / or metal fiber including copper, nickel, aluminum, silver, etc.; conductive polymers (e.g., conductive polymers) such as polyphenylene derivatives; or mixtures thereof.

[0131] Al foil may be used as a positive electrode current collector, but is not limited thereto.

[0132] Negative electrode active material

[0133] The negative electrode active material may include a material that reversibly intercalates / deintercalates lithium ions, lithium metal, a lithium metal alloy, a material capable of doping / de-doping lithium, and / or a transition metal oxide.

[0134] The material that reversibly intercalates / deintercalates lithium ions may include a carbon-based negative electrode active material, such as crystalline carbon, amorphous carbon, or a combination thereof. The crystalline carbon may be graphite (such as amorphous, flaky, lamellar, spherical, and / or fibrous natural graphite and / or artificial graphite), and the amorphous carbon may be soft carbon, hard carbon, mesophase pitch carbonization product, calcined coke, etc.

[0135] The lithium metal alloy includes an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0136] The material capable of doping / de-doping lithium may be a Si-based negative electrode active material and / or a Sn-based negative electrode active material. The Si-based negative electrode active material may include silicon, a silicon-carbon composite, SiO x (0 < x ≤ 2), a Si-Q alloy (where Q is selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements (excluding Si), Group 15 elements, Group 16 elements, transition metals, rare earth elements, and combinations thereof). The Sn-based negative electrode active material may include Sn, SnO 2 , a Sn-based alloy, SnO x (0 < x < 2), or a combination thereof.

[0137] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to some embodiments, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, the silicon-carbon composite may include secondary particles (cores) in which primary silicon particles are aggregated and an amorphous carbon coating (shell) on the surface of the secondary particles. The amorphous carbon may also be between the primary silicon particles, and, for example, the primary silicon particles may be coated with amorphous carbon. The secondary particles may be dispersed in an amorphous carbon matrix.

[0138] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include: a core including crystalline carbon and silicon particles and an amorphous carbon coating on the surface of the core.

[0139] The Si-based negative electrode active material and / or the Sn-based negative electrode active material may be used in combination with the carbon-based negative electrode active material.

[0140] Negative electrode

[0141] The negative electrode for a rechargeable lithium battery includes a negative electrode current collector and a negative electrode active material layer on the negative electrode current collector. The negative electrode active material layer may include a negative electrode active material, and may further include a binder and / or a conductive material (eg, an electrically conductive material).

[0142] For example, the negative electrode active material layer may include about 90 wt % to about 99 wt % of the negative electrode active material, about 0.5 wt % to about 5 wt % of the binder, and about 0 wt % to about 5 wt % of the conductive material based on the total amount of the negative electrode active material layer.

[0143] The binder is used to well attach the negative electrode active material particles to each other and also to well attach the negative electrode active material to the current collector. The binder may include a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof.

[0144] The non-aqueous binder may include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof.

[0145] The aqueous binder can be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinyl pyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinyl pyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol and combinations thereof.

[0146] When the aqueous binder is used as a binder in the negative electrode active material layer, a cellulose compound capable of imparting or increasing viscosity may be further included. The cellulose compound may include at least one of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose and an alkali metal salt thereof. The alkali metal may include Na, K and / or Li.

[0147] The dry binder may be a polymer material that can be fibrous (eg, can be fibrillated or fiberized), and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or a combination thereof.

[0148] Conductive material Any suitable material that is used to impart conductivity (e.g., electrical conductivity) to the electrode and does not cause chemical changes (e.g., does not cause undesirable chemical changes) and conducts electrons can be used for 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, carbon nanofiber, and carbon nanotube; metal-based materials in the form of metal powder and / or metal fiber including copper, nickel, aluminum, silver, etc.; conductive polymers (e.g., conductive polymers) such as polyphenylene derivatives; or mixtures thereof.

[0149] The negative electrode current collector may include copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal (eg, an electrically conductive metal), and / or combinations thereof.

[0150] Diaphragm

[0151] Depending on the type (or kind) of the rechargeable lithium battery, the separator may be present between the positive electrode and the negative electrode. The separator may include a polyethylene separator, a polypropylene separator, a polyvinylidene fluoride separator, or a multilayer film of two or more layers thereof (such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, a polypropylene / polyethylene / polypropylene three-layer separator, etc.).

[0152] The separator may include a porous substrate and a coating on one or both surfaces (eg, two opposite surfaces) of the porous substrate, the coating including an organic material, an inorganic material, or a combination thereof.

[0153] The porous substrate can be a polymer film formed by: any polymer selected from polyolefins (such as polyethylene and polypropylene), polyesters (such as polyethylene terephthalate and polybutylene terephthalate), polyacetals, polyamides, polyimides, polycarbonates, polyether ketones, polyether ketones, polyether imides, polyamide-imides, polybenzimidazoles, polyether sulfones, polyphenylene oxides, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fibers, polytetrafluoroethylene (e.g., Teflon), or copolymers or mixtures of two or more thereof.

[0154] The organic material may include a polyvinylidene fluoride-based polymer and / or a (meth)acrylic-based polymer.

[0155] The inorganic material may include a 2 O 3 、SiO 2 、TiO 2 SnO 2 、CeO 2 , MgO, NiO, CaO, GaO, ZnO, ZrO 2 , Y 2 O 3 、SrTiO3 、BaTiO 3 Mg(OH) 2 , boehmite and inorganic particles of combinations thereof, but are not limited thereto.

[0156] An organic material and an inorganic material may be mixed together in one coating layer, or a coating layer including an organic material and a coating layer including an inorganic material may be stacked.

[0157] Rechargeable lithium battery

[0158] The rechargeable lithium battery may be classified into a cylindrical battery, a prismatic battery, a pouch type battery, a coin type battery, etc., depending on the shape of the rechargeable lithium battery.

[0159] Figure 1 to Figure 4 A schematic diagram illustrating a rechargeable lithium battery according to some embodiments. Figure 1 A cylindrical battery is shown, Figure 2 A prismatic cell is shown, and Figure 3-4 A pouch-type battery is shown.

[0160] refer to Figure 1 to Figure 4 , the rechargeable lithium battery 100 includes an electrode assembly 40 including a separator 30 between a positive electrode 10 and a negative electrode 20, and a case in which the electrode assembly 40 is accommodated. The positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated with an electrolyte solution.

[0161] like Figure 1 As shown in FIG. 1 , the rechargeable lithium battery 100 may include a sealing member 60 that seals the case 50 .

[0162] exist Figure 2 In the embodiment, the rechargeable lithium battery 100 may include a positive electrode lead tab 11 , a positive electrode terminal 12 , a negative electrode lead tab 21 , and a negative electrode terminal 22 .

[0163] like Figure 3-4 As shown in FIG. 1 , the rechargeable lithium battery 100 may include an electrode tab 70 ( Figure 4 ) For example, the positive electrode tab 71 and the negative electrode tab 72 ( Figure 3 ).

[0164] As an example, the driving voltage of the rechargeable lithium battery may be 4.3 V or higher or 4.35 V or higher. Even under the high voltage operating environment as described above, when the lithium nickel composite oxide represented by Chemical Formula 3 is used together with the electrolyte solution including the first compound and the second compound described above, stable battery performance can be achieved under high voltage / high temperature conditions.

[0165] A rechargeable lithium battery according to some embodiments may be applied to automobiles, mobile phones, and / or various appropriate types (or kinds) of electronic devices, but the present disclosure is not limited thereto.

[0166] The following describes embodiments and comparative examples of the present disclosure. However, the embodiments described below are merely examples of the present disclosure, and the present disclosure is not limited to the embodiments described below.

[0167] Example

[0168] Example 1

[0169] A non-aqueous organic solvent was prepared by sequentially mixing ethylene carbonate (EC), ethyl methyl carbonate (MEC), and dimethyl carbonate (DMC) at a volume ratio of 20:40:40, and dissolving 1.15 M of LiPF 6 Lithium salt is used to prepare the basic electrolyte solution.

[0170] Triallyl isocyanurate as a first compound and 2-fluoro-4-methyl-1,3,2-dioxaphospholane as a second compound were added to the base electrolyte solution to prepare an electrolyte solution.

[0171] Herein, 0.5 wt % of the first compound and 0.5 wt % of the second compound were added based on the total amount of the electrolyte solution.

[0172] As the positive electrode active material, NMX (LiNi 0.75 Mn 0.23 Al 0.02 O 2 ), polyvinylidene fluoride as a binder and ketjen black as a conductive material were mixed together in a weight ratio of 97:2:1, and then dispersed in N-methylpyrrolidone to prepare a positive electrode active material slurry. The positive electrode active material slurry was coated on a 14 μm thick Al foil current collector, dried at 110°C, and pressed to prepare a positive electrode.

[0173] In addition, a negative electrode active material slurry was prepared by mixing artificial graphite as a negative electrode active material, styrene-butadiene rubber as a binder, and carboxymethyl cellulose as a thickener in a weight ratio of 97:1:2, and dispersing the mixture in distilled water. The negative electrode active material slurry was coated on a 10 μm thick Cu foil current collector, dried at 100° C., and pressed to prepare a negative electrode.

[0174] A 25 μm thick separator having a polyethylene / polypropylene two-layer separator was inserted between the positive electrode and the negative electrode to prepare an electrode assembly, and a 4.45V-grade rechargeable lithium battery cell according to Example 1 (this means that the driving voltage of the rechargeable lithium battery cell is 4.45V) was prepared by inserting the electrode assembly into a cylindrical type battery case and injecting the prepared electrolyte solution therein.

[0175] Comparative Example 1

[0176] A rechargeable lithium battery cell was prepared in substantially the same manner as in Example 1, except that the electrolyte solution was prepared without adding the first compound and the second compound.

[0177] Comparative Example 2

[0178] A rechargeable lithium battery cell was prepared in substantially the same manner as in Example 1, except that the electrolyte solution was prepared without adding the second compound.

[0179] Comparative Example 3

[0180] A rechargeable lithium battery cell was prepared in substantially the same manner as in Example 1, except that the electrolyte solution was prepared without adding the first compound.

[0181] Comparative Example 4

[0182] A rechargeable lithium battery cell was prepared in substantially the same manner as in Example 1, except that the electrolyte solution was prepared by adding triallyl cyanurate represented by Chemical Formula a instead of triallyl isocyanurate as the first compound.

[0183] Chemical formula a

[0184]

[0185] Comparative Example 5

[0186] A rechargeable lithium battery cell was prepared in substantially the same manner as in Example 1, except that NCA (LiNi 0.5 Co 0.2 Al 0.3 O 2 ) as the positive electrode active material to prepare the positive electrode.

[0187] Evaluation Example

[0188] Evaluation Example 1: Evaluation of high temperature storage characteristics

[0189] The ΔV / ΔI (voltage change / current change) of the rechargeable lithium battery cells of Example 1 and Comparative Examples 1 to 5 were measured to evaluate the initial DC resistance (DCIR). Subsequently, after the internal maximum energy state of each of the battery cells was brought to a fully charged state (SOC 100%), the battery cells were left to stand at a high temperature of 60° C. for 30 days, and then the DC resistance (DCIR) was measured again.

[0190] The DCIR increase rate (%) was calculated according to Equation 1, and the results are shown in Table 1.

[0191] Equation 1

[0192] DCIR increase rate (%) = {(DCIR after 30 days) / (initial DCIR)}

[0193] Table 1

[0194]

[0195] Referring to Table 1, compared with Comparative Examples 1 to 5, Example 1 exhibits a low DCIR increase rate at high temperatures, and thus has excellent storage characteristics at high temperatures.

[0196] Evaluation Example 2: Evaluation of Room-Temperature Cycle Life Characteristics

[0197] The rechargeable lithium battery cells of Example 1 and Comparative Examples 1 to 5 were charged and discharged once at 0.2 C to measure the charge and discharge capacities.

[0198] In addition, the rechargeable lithium battery cells of Example 1 and Comparative Examples 1 to 5 were charged to a charge upper limit voltage of 4.4 V and discharged to 2.5 V at 0.2 C under a constant current condition to measure initial discharge capacity.

[0199] The battery cell was charged at 0.33C (CC / CV, 4.4V, 0.025C cutoff) / discharged at 1.0C (CC, 2.5V cutoff) for 200 cycles at 25°C to measure the 200th discharge capacity.

[0200] The ratio of the 200th discharge capacity to the initial discharge capacity is shown in Table 2 as capacity recovery rate (%, recovery).

[0201] Evaluation Example 3: Evaluation of gas generation after high-temperature storage

[0202] The rechargeable lithium battery cells of Example 1 and Comparative Examples 1 to 5 were left standing at 60° C. for 7 days, and then the gas generation amounts on the 1st and 7th days were measured by refinery gas analysis (RGA), and the results are shown in Table 2.

[0203] The gas increase rate (%) was calculated according to Equation 2, and the results are shown in Table 2.

[0204] Equation 2

[0205] Gas increase rate (%) = {(gas generation on the 7th day) / (gas generation on the 1st day)}

[0206] Table 2

[0207]

[0208]

[0209] Referring to Table 2, compared with Comparative Examples 1 to 5, Example 1 exhibits a high capacity recovery rate at room temperature and thus has excellent room temperature cycle life characteristics.

[0210] In addition, referring to Table 2, compared with Comparative Examples 1 to 5, Example 1 exhibited a significantly reduced gas increase rate after high temperature storage.

[0211] While the subject matter of the present disclosure has been described in connection with what are presently considered to be practical example embodiments, it should be understood that the disclosure is not limited to the disclosed embodiments, but, on the contrary, is intended to cover one or more suitable various modifications and equivalent arrangements included within the spirit and scope of the claims and their equivalents.

Claims

1. A rechargeable lithium battery comprising: a positive electrode, including a positive electrode active material; a negative electrode, including a negative electrode active material; as well as An electrolyte solution for a rechargeable lithium battery, comprising a non-aqueous organic solvent, a lithium salt and an additive, wherein the additive comprises a first compound represented by Chemical Formula 1 and a second compound represented by Chemical Formula 2, and The positive electrode active material includes a lithium nickel composite oxide represented by Chemical Formula 3: Chemical formula 1 Wherein, in Chemical Formula 1, R 1 ~R 3 Each is independently hydrogen, cyano, halogen, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C2-C20 alkenyl, substituted or unsubstituted C2-C20 alkynyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C2-C20 heterocycloalkyl, substituted or unsubstituted C3-C20 cycloalkenyl, substituted or unsubstituted C6-C20 aryl, or substituted or unsubstituted C2-C20 heteroaryl; Chemical formula 2 Wherein, in Chemical Formula 2, X 1 is fluoro, chloro, bromo or iodo, and R 4 ~R 9 are each independently hydrogen, cyano, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxy, substituted or unsubstituted C2-C20 alkenyl, substituted or unsubstituted C2-C20 alkynyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C6-C20 aryl, or substituted or unsubstituted C2-C20 heteroaryl, and n is an integer of 0 or 1; Chemical formula 3 Li w Ni x Mr y M 1 1-x-y O2 Among them, in chemical formula 3, 0.5≤w≤1.8, 0.05≤x<1, 0<y≤0.7, and M 1 It is Al, Fe, B, Ce, Cr, F, Mg, Mo, Nb, P, S, Si, Sr, Ti, V, W, Zr or a combination thereof.

2. The rechargeable lithium battery of claim 1, wherein: In Chemical Formula 1, R 1 ~R 3 Each is independently a substituted or unsubstituted C1-C20 alkyl group or a substituted or unsubstituted C2-C20 alkenyl group.

3. The rechargeable lithium battery of claim 1, wherein: The first compound represented by Chemical Formula 1 is any one or more selected from the compounds listed in Group 1: Group 1 4. The rechargeable lithium battery of claim 1, wherein: The second compound represented by Chemical Formula 2 includes a compound represented by Chemical Formula 2A or Chemical Formula 2B: Chemical formula 2B Wherein, in Chemical Formula 2A and Chemical Formula 2B, X 1 is a fluoro group, a chloro group, a bromo group or an iodo group, R 4 and R 5 is the same as in Chemical Formula 2, and R 6 ~R 9 Each is independently hydrogen, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C1-C10 alkoxy, substituted or unsubstituted C2-C10 alkenyl or substituted or unsubstituted C2-C10 alkynyl.

5. The rechargeable lithium battery of claim 4, wherein: In Chemical Formula 2A, R 6 and R 7 are each hydrogen and are selected from R 8 and R 9 At least one of them is a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C1-C10 alkoxy group, a substituted or unsubstituted C2-C10 alkenyl group, or a substituted or unsubstituted C2-C10 alkynyl group.

6. The rechargeable lithium battery of claim 1, wherein: The second compound represented by Chemical Formula 2 is selected from the compounds listed in Group 2: Group 2 7. The rechargeable lithium battery of claim 1, wherein: The first compound is included in an amount of 0.05 wt % to 3 wt % based on the total weight of the electrolyte solution.

8. The rechargeable lithium battery of claim 1, wherein: The second compound is included in an amount of 0.05 wt % to 3 wt % based on the total weight of the electrolyte solution.

9. The rechargeable lithium battery of claim 1, wherein: The additives further include other additives, which include vinylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, vinylethylene carbonate, adiponitrile, succinonitrile, 1,3,6-hexanetricyanide, propene sultone, propane sultone, lithium tetrafluoroborate, lithium difluorophosphate, 2-fluorobiphenyl or a combination thereof.

10. The rechargeable lithium battery of claim 1, wherein: In chemical formula 3, 0.9≤w≤1.1, 0.6≤x<1, and 0 <y≤0.4。 11. The rechargeable lithium battery of claim 1, wherein: The driving voltage of the rechargeable lithium battery is 4.3V or higher.

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