Electrolyte for rechargeable lithium battery and rechargeable lithium battery including same

Abstract

The invention relates to an electrolyte for a rechargeable lithium battery and a rechargeable lithium battery including the same. An electrolyte for a rechargeable lithium battery according to some embodiments includes: 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. Definitions of Chemical Formulae 1 and 2 are as described in the specification. Chemical formula 1 # imgabs0 # and chemical formula 2 # imgabs1 #

Description

Technical Field

[0001] The present disclosure relates to an electrolyte for a rechargeable lithium battery and a rechargeable lithium battery including the same. Background Art

[0002] Recently, with the rapid popularization of electronic devices using batteries (such as mobile phones, laptop computers, and / or electric vehicles), the demand or expectation for rechargeable lithium batteries having a relatively high energy density and high capacity has rapidly increased. Accordingly, research and development for improving the performance of rechargeable lithium batteries are actively underway or being carried out.

[0003] A rechargeable lithium battery includes a positive electrode and a negative electrode (each including an active material capable of intercalating and deintercalating lithium ions) and an electrolyte, and if (for example, when) lithium ions intercalate into and deintercalate from the positive electrode and the negative electrode, electric energy is generated through oxidation and reduction reactions.

[0004] Recently, active research has been conducted on rechargeable lithium batteries having high capacity, high energy density, and high safety to be used as a drive power source for hybrid vehicles and / or electric vehicles, or as a power storage power source (for example, for an energy storage station and / or a power wall).

[0005] In a rechargeable lithium battery, the electrolyte plays a role (for example, an important role) in transporting lithium ions, and by including an organic solvent and a lithium salt, significantly higher ionic (for example, ion) conductivity can be exhibited. These electrolytes play a role (for example, an important role) in determining the safety and performance of rechargeable lithium batteries.

[0006] When a rechargeable lithium battery is in an overcharged state, the battery rapidly generates heat and also generates gas, causing battery safety problems due to, for example, cell explosion. In addition, if (for example, when) a rechargeable lithium battery is rapidly charged, there are problems of lithium ion electrodeposition on the negative electrode and an increase in the resistance inside the battery.

[0007] Accordingly, there is a need or expectation to develop an electrolyte to implement a battery having excellent or appropriate safety even under overcharging and rapid charging conditions. Summary of the Invention

[0008] Aspects according to some embodiments relate to an electrolyte for a rechargeable lithium battery, which has excellent or appropriate safety and excellent or appropriate room temperature cycle life characteristics under overcharging and rapid charging conditions.

[0009] Aspects according to some embodiments relate to a rechargeable lithium battery including the electrolyte.

[0010] Other aspects will be set forth in part in the following description and in part will be obvious from the description, or can be learned by practice of the presented embodiments of the disclosure.

[0011] In one or more embodiments, an electrolyte for a rechargeable lithium battery includes: a non-aqueous organic solvent; a lithium salt; and an additive,

[0012] wherein the additive includes a first compound represented by Chemical Formula 1 and a second compound represented by Chemical Formula 2.

[0013] Chemical Formula 1

[0014]

[0015] Chemical Formula 2

[0016]

[0017] In Chemical Formula 1,

[0018] R 1 and R 2 may each independently be a substituted or unsubstituted C1-C20 alkyl group or a substituted or unsubstituted C6-C30 aryl group, provided that at least one of R 1 and R 2 is a substituted or unsubstituted C6-C30 aryl group,

[0019] In Chemical Formula 2,

[0020] M is boron (B) or phosphorus (P),

[0021] R 3 and R 4 may each independently be hydrogen, a halogen group (F, Cl, Br, or I), or a substituted or unsubstituted C1-C10 alkyl group, R 5 may be a substituted or unsubstituted methylene group,

[0022] n is an integer from 1 to 3, and

[0023] m is 0 or 1, and m1 and m2 are each independently integers from 0 to 2.

[0024] In one or more embodiments, a rechargeable lithium battery includes: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; a separator between the positive electrode and the negative electrode; and the foregoing electrolyte.

[0025] An electrolyte for a rechargeable lithium battery according to one or more embodiments has excellent or appropriate safety under overcharge and fast charge conditions, and a rechargeable lithium battery having excellent or appropriate room temperature cycle life characteristics can be implemented. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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 embodiments of the present disclosure and, together with the description, are used to explain the principles of the present disclosure. In the drawings,

[0027] Figure 1 is a schematic illustration of a cylindrical battery according to some embodiments.

[0028] Figure 2 is a schematic illustration of a prismatic battery according to some embodiments.

[0029] Figure 3 is a schematic illustration of a pouch or pouch-like battery according to some embodiments.

[0030] Figure 4 is a schematic illustration of a pouch or pouch-like battery according to some embodiments.

[0031] Figure 5 is a graph showing the results of overcharge and fast charge evaluations of rechargeable lithium battery cells manufactured in Examples 1 to 2 and Comparative Examples 1 to 4.

[0032] Figure 6 is a graph showing the results of room temperature cycle life evaluations of rechargeable lithium battery cells manufactured in Examples 1 to 2 and Comparative Examples 1 to 4.

[0033] REFERENCE NUMERALS

[0034] 100: Rechargeable lithium battery; 10: Positive electrode

[0035] 11: Positive electrode lead tab; 12: Positive electrode terminal

[0036] 20: Negative electrode; 21: Negative electrode lead tab

[0037] 22: Negative electrode terminal; 30: Separator

[0038] 40: Electrode assembly; 50: Housing

[0039] 60: Sealing member; 70: Electrode tab

[0040] 71: Positive electrode tab; 72: Negative electrode tab DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] 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.

[0042] As used herein, if (e.g., when) no specific definition is otherwise provided, it will be understood that if (e.g., when) an element (such as a layer, film, region, or substrate) is referred to as “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 an intervening element may also be present.

[0043] Unless otherwise indicated in this specification, the content expressed in the singular may also include the plural. Additionally, unless otherwise indicated, “A or B” may mean “including A”, “including B”, or “including A and B”.

[0044] As used herein, “a combination thereof” refers to a mixture, stack, composite, copolymer, alloy, blend, reaction product, etc. of components.

[0045] As used herein, if (e.g., when) no definition is otherwise provided, the particle size may be the average particle size. Additionally, the particle size refers to the average particle size (D 50 ), which refers to the diameter of the particle at which the cumulative volume in the particle size distribution is 50% by volume. The average particle size (D 50 ) can be measured by appropriate methods (e.g., known to those skilled in the art), such as by a particle size analyzer, a transmission electron microscope image, or a scanning electron microscope image. In one or more embodiments, a dynamic light scattering measurement device is used for data analysis, and the number of particles in each particle size range is counted. Thus, the average particle size (D 50 ) value can be easily obtained by calculation. In one or more embodiments, the average particle size (D 50 ) can be measured using the laser diffraction method. When measured using 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 measurement device (e.g., Microtrac MT 3000), and ultrasonic waves with an output of 60W and a frequency of about 28kHz can be irradiated to calculate the average particle size (D 50 ) based on the 50% particle size distribution in the measurement device. And, unless otherwise defined, in this disclosure, if (e.g., when) the particles or grains are spherical, the term “particle size” refers to the average diameter, and if (e.g., when) the particles or grains are non-spherical, the term “particle size” refers to the average major axis length.

[0046] As used herein, if (e.g., when) defined otherwise, the term "substituted" means that at least one hydrogen of a substituent or compound is replaced by the following: deuterium, a halogen group, a hydroxyl group, an amino group, a C1-C30 amino group, a nitro group, a C1-C40 silyl group, a C1-C30 alkyl group, a C1-C10 alkylsilyl group, a C6-C30 arylsilyl group, a C3-C30 cycloalkyl group, a C3-C30 heterocycloalkyl group, a C6-C30 aryl group, a C2-C30 heteroaryl group, a C1-C20 alkoxy group, a C1-C10 fluoroalkyl group, a cyano group, and / or a combination thereof (e.g., any suitable combination).

[0047] For example, the term "substituted" may mean that at least one hydrogen of a substituent or compound is replaced by the following: deuterium, a halogen group, a C1-C30 alkyl group, a C1-C10 alkylsilyl group, a C6-C30 arylsilyl group, a C3-C30 cycloalkyl group, a C3-C30 heterocycloalkyl group, a C6-C30 aryl group, a C2-C30 heteroaryl group, a C1-C10 fluoroalkyl group, or a cyano group. For example, the term "substituted" may mean that at least one hydrogen of a substituent or compound is replaced by the following: deuterium, a halogen group, a C1-C20 alkyl group, a C6-C30 aryl group, a C1-C10 fluoroalkyl group, or a cyano group. In one or more embodiments, the term "substituted" may mean that at least one hydrogen of a substituent or compound is replaced by the following: deuterium, a halogen group, a C1-C5 alkyl group, a C6-C18 aryl group, a C1-C5 fluoroalkyl group, a cyano group. For example, the term "substituted" may mean that at least one hydrogen of a substituent or compound is replaced by the following: deuterium, a cyano group, a halogen group, a methyl group, an ethyl group, a propyl group, a butyl group, a phenyl group, a biphenyl group, a terphenyl group, a trifluoromethyl group, or a naphthyl group.

[0048] An electrolyte for a rechargeable lithium battery according to one or more embodiments includes: a non-aqueous organic solvent; a lithium salt; and an additive, wherein the additive includes a first compound and a second compound.

[0049] When the first compound, the second compound, and the lithium salt are used in combination, a rechargeable lithium battery having excellent or suitable safety and excellent or suitable room temperature cycle life characteristics under overcharge and fast charge conditions can be implemented.

[0050] First compound

[0051] The first compound is a sulfoxide compound, which effectively inhibits the heating temperature of the battery (e.g., inhibits the temperature increase due to heating) under overcharge operating conditions.

[0052] The first compound is represented by Chemical Formula 1.

[0053] Chemical Formula 1

[0054]

[0055] In Chemical Formula 1, R 1 and R 2 may each independently be a substituted or unsubstituted C1-C20 alkyl group or a substituted or unsubstituted C6-C30 aryl group, provided that at least one of R 1 and R 2 is a substituted or unsubstituted C6-C30 aryl group.

[0056] For example, at least one of R 1 and R 2 may be a substituted or unsubstituted C6-C30 aryl group.

[0057] In one or more embodiments, the first compound represented by Chemical Formula 1 may be represented by Chemical Formula 1-1 or Chemical Formula 1-2. In an embodiment, the first compound represented by Chemical Formula 1 may be represented by Chemical Formula 1-1.

[0058] Chemical Formula 1-1

[0059]

[0060] In Chemical Formula 1-1,

[0061] R 1a may be a substituted or unsubstituted C1-C20 alkyl group, and

[0062] H a ~H e may each independently be hydrogen, a halogen group, a hydroxyl group, a cyano group, a nitro group, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkoxy group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a substituted or unsubstituted C3-C20 cycloalkyl group, a substituted or unsubstituted C6-C20 aryl group, or a substituted or unsubstituted C2-C20 heteroaryl group.

[0063] As a specific example, H a ~H e may each independently be hydrogen, a halogen group, a substituted or unsubstituted C1-C20 alkyl group, or a substituted or unsubstituted C1-C20 alkoxy group.

[0064] Chemical Formula 1-2

[0065]

[0066] In Chemical Formula 1-2,

[0067] H a ~H jEach may independently be hydrogen, a halogen group, a hydroxyl group, a cyano group, a nitro group, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkoxy group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a substituted or unsubstituted C3-C20 cycloalkyl group, a substituted or unsubstituted C6-C20 aryl group, or a substituted or unsubstituted C2-C20 heteroaryl group.

[0068] In some embodiments, H a ~H j Each may independently be hydrogen, a halogen group, a substituted or unsubstituted C1-C20 alkyl group, or a substituted or unsubstituted C1-C20 alkoxy group.

[0069] In an embodiment, the first compound may include one or more (e.g., any one) of the compounds listed in Group 1.

[0070] Group 1

[0071]

[0072] In one or more embodiments, based on the total weight (100 wt%) of the electrolyte for a rechargeable lithium battery, the amount of the first compound included may be greater than about 0.05 wt% or greater than or equal to about 0.1 wt%, and less than about 10 wt% or less than or equal to about 5 wt%.

[0073] For example, the amount of the first compound included may be greater than about 0.05 wt% and less than about 10 wt%, for example, greater than about 0.05 wt% and less than or equal to about 5 wt%, greater than or equal to about 0.1 wt% and less than about 10 wt%, or from about 0.1 wt% to about 5 wt%.

[0074] If, based on the total weight of the electrolyte for a rechargeable lithium battery, the amount of the first compound included is less than or equal to about 0.05 wt%, the effect of improving the safety of the battery during overcharging is minimal or reduced, and if the amount of the first compound included is greater than or equal to about 10 wt%, the resistance of the battery increases (or increases excessively).

[0075] The second compound

[0076] The second compound is a lithium salt having an oxalate group. If (e.g., when) the battery operates, the second compound is rapidly reduced and decomposed to form a SEI (solid electrolyte interface) film on the negative electrode, which prevents or substantially prevents the electrodeposition of lithium ions on the negative electrode and prevents an increase in the internal resistance of the battery.

[0077] The second compound is represented by Chemical Formula 2.

[0078] Chemical Formula 2

[0079]

[0080] In Chemical Formula 2,

[0081] M is B (boron) or P (phosphorus),

[0082] R 3 and R 4 can each independently be hydrogen, a halogen group (F, Cl, Br, or I), or a substituted or unsubstituted C1-C10 alkyl group, and R 5 can be a substituted or unsubstituted methylene group,

[0083] n is an integer from 1 to 3, and

[0084] m is 0 or 1, and m1 and m2 are each independently integers from 0 to 2 (i.e., 0, 1, and 2).

[0085] For example, M can be B, and R 3 and R 4 can each independently be hydrogen or a halogen group (F, Cl, Br, or I), n can be 1 or 2, and m can be 0 or 1.

[0086] In one or more embodiments, the second compound represented by Chemical Formula 2 may include one or more compounds selected from the group consisting of the compounds represented by Chemical Formulas 2-1 to 2-8. In some embodiments, the second compound represented by Chemical Formula 2 may include one or more compounds selected from the group consisting of the compounds represented by Chemical Formulas 2-1 to 2-4 (e.g., any one).

[0087] Chemical Formula 2-1

[0088]

[0089] Chemical Formula 2-2

[0090]

[0091] Chemical Formula 2-3

[0092]

[0093] Chemical Formula 2-4

[0094]

[0095] Chemical Formula 2-5

[0096]

[0097] Chemical Formula 2-6

[0098]

[0099] Chemical formula 2-7

[0100]

[0101] Chemical formula 2-8

[0102]

[0103] In one or more embodiments, based on the total weight of the electrolyte for a rechargeable lithium battery, the amount of the second compound included may be greater than about 0.05 wt% or greater than or equal to about 0.1 wt%, and less than about 5 wt% or less than or equal to about 3 wt%.

[0104] For example, based on the total weight of the electrolyte for a rechargeable lithium battery, the amount of the second compound included may be greater than about 0.05 wt% and less than about 5 wt%, for example, greater than about 0.05 wt% and less than or equal to about 3 wt%, greater than or equal to about 0.1 wt% and less than about 5 wt%, or from about 0.1 wt% to about 3 wt%.

[0105] If, based on the total weight of the electrolyte for a rechargeable lithium battery, the amount of the second compound included is less than or equal to about 0.05 wt% or greater than or equal to about 5 wt%, the room temperature cycle life characteristics of the battery may be reduced.

[0106] In one or more embodiments, the weight ratio of the first compound and the second compound included may be from about 0.05:1 to about 50:1, for example, the weight ratio of the first compound and the second compound included is from about 0.05:1 to about 40:1, the weight ratio of the first compound and the second compound included is from about 0.1:1 to about 50:1, or the weight ratio of the first compound and the second compound included is from about 0.1:1 to about 40:1.

[0107] If the weight ratio of the first compound and the second compound satisfies the above numerical range, a rechargeable lithium battery having excellent or appropriate safety and excellent or appropriate room temperature cycle life characteristics under overcharge and fast charge conditions can be implemented.

[0108] Lithium salt

[0109] 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.

[0110] The concentration of the lithium salt can be from about 0.1 M to about 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte has appropriate or proper conductivity and viscosity, so excellent or proper performance of the electrolyte can be achieved, and lithium ions can move effectively.

[0111] For example, the lithium salt can include 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 )(x and y are each independently an integer from 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, and / or a combination thereof (for example, any suitable combination).

[0112] Non-aqueous organic solvent

[0113] The non-aqueous organic solvent serves as a medium for transporting (for example, transferring) ions participating in the electrochemical reaction of the battery.

[0114] The non-aqueous organic solvent can include carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, aprotic solvents, and / or a combination thereof (for example, any suitable combination).

[0115] Carbonate solvents may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl 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, decanolide, mevalonolactone, valerolactone, caprolactone, etc. Ether solvents may include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. Additionally, ketone solvents may include cyclohexanone, etc. Alcohol solvents may include ethanol, isopropanol, etc., and aprotic solvents may include: nitriles, such as R-CN (where R is a C2-C20 straight-chain, branched-chain or cycloalkyl group and may include double bonds, aromatic rings or ether bonds), etc.; amides, such as dimethylformamide; dioxolanes, such as 1,3-dioxolane, 1,4-dioxolane, etc.; sulfolane, etc.

[0116] The non-aqueous organic solvent may be used alone or in combination of two or more.

[0117] Additionally, if (e.g., when) a carbonate solvent is used, a cyclic carbonate and a chain carbonate may be mixed and used, and the cyclic carbonate and the chain carbonate may be mixed in a volume ratio of about 1:1 to about 1:9.

[0118] Rechargeable lithium battery

[0119] Some embodiments provide a rechargeable lithium battery including the aforementioned electrolyte.

[0120] A rechargeable lithium battery according to one or more embodiments includes: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; a separator between the positive electrode and the negative electrode; and an electrolyte.

[0121] Depending on the shape of the rechargeable lithium battery, the rechargeable lithium battery may be classified as a cylindrical battery, a prismatic battery, a pouch or pouch-like battery, a coin or coin-like battery, etc. Figures 1 to 4 Is a schematic diagram of a rechargeable lithium battery according to one or more embodiments. Figure 1 Shows a cylindrical battery, Figure 2 Shows a prismatic battery, and Figure 3 And Figure 4 And shows a pouch or pouch-like battery. Referring to Figures 1 to 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 housing 50 including (e.g., accommodating) the electrode assembly 40 therein. The positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated with the electrolyte. As Figure 1As shown, the rechargeable lithium battery 100 may include a sealing member 60 that seals the housing 50. Additionally, in Figure 2 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. As Figure 3 and Figure 4 shown, the rechargeable lithium battery 100 includes electrode tabs 70, i.e., a positive electrode tab 71 and a negative electrode tab 72, which serve as a circuit path for leading the current formed in the electrode assembly 40 to the outside.

[0122] The rechargeable lithium battery according to one or more embodiments may be applied to an automobile, a mobile phone, and / or one or more other suitable types (kinds) of electronic devices, but the present disclosure is not limited thereto.

[0123] Positive electrode active material

[0124] The positive electrode active material may include a compound (lithiated insertion compound) capable of inserting and extracting lithium. For example, at least one composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and one or more (e.g., any suitable) combinations thereof may be used.

[0125] The composite oxide may be a lithium transition metal composite oxide, and non-limiting examples thereof may include lithium nickel-based oxides (e.g., nickel cobalt aluminum-based lithium composite oxides (e.g., LiNi 0.91 Co 0.07 Al 0.02 O 2 )), lithium cobalt-based oxides, lithium manganese-based oxides, lithium iron phosphate-based compounds, cobalt-free lithium nickel manganese-based oxides, and / or combinations thereof (e.g., any suitable).

[0126] For example, one or more compounds represented by any of the following chemical formulas may be used. Li a A 1-b X b O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, and 0 ≤ c ≤ 0.05); Li a Mn 2-b X b O 4-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, and 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b X c O 2-α D α(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5, and 0 < α < 2); 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, and 0 < α < 2); Li a Ni b Co c L 1 d G e O 2 (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, and 0 ≤ e ≤ 0.1); Li a NiG b O 2 (0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a CoG b O 2 (0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a Mn 1-b G b O 2 (0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a Mn 2 G b O 4 (0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a Mn 1-g G g PO 4 (0.90 ≤ a ≤ 1.8, and 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)

[0127] In the above chemical formulas, A is Ni, Co, Mn, and / or any suitable combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, and / or any suitable combination thereof; D is O, F, S, P, and / or any suitable combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and / or any suitable combination thereof; and L1 It is Mn, Al, and / or a combination thereof (e.g., any suitable combination).

[0128] For example, the positive electrode active material may be a high-nickel type positive electrode active material. Based on the metal excluding lithium in 100 mol% of the lithium transition metal composite oxide (i.e., the high-nickel type positive electrode active material), the nickel content (e.g., amount) of the high-nickel type positive electrode active material is 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%. The high-nickel type positive electrode active material can achieve high capacity and can be applied to high-capacity, high-energy density rechargeable lithium batteries.

[0129] Positive electrode

[0130] 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.

[0131] For example, the positive electrode may further include a component that can be used as a sacrificial positive electrode.

[0132] Based on 100 wt% of the positive electrode active material layer (e.g., total weight), the amount of the positive electrode active material may be about 90 wt% to about 99 wt%, and based on 100 wt% of the positive electrode active material layer, the amounts of the binder and the conductive material may be about 0.5 wt% to about 5 wt% respectively.

[0133] The binder is used to attach the positive electrode active material particles to each other (e.g., attach well), and is also used to attach the positive electrode active material (e.g., attach well) to the positive electrode current collector. Examples of the binder may include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylate esterified styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, nylon, etc., but the present disclosure is not limited thereto.

[0134] Conductive materials are used to impart conductivity to the electrodes, and any suitable material that does not cause chemical changes and conducts electrons can be used in the battery. Examples of conductive materials can include carbonaceous materials (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and / or carbon nanotube); metallic materials including copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fiber; conductive polymers (such as polyphenylene derivatives); and / or their (e.g., any suitable) mixtures.

[0135] Al foil can be used as the positive electrode current collector, but the present disclosure is not limited thereto.

[0136] Negative electrode active material

[0137] The negative electrode active material can include materials that reversibly intercalate / deintercalate lithium ions, lithium metal, lithium metal alloys, materials capable of doping / de-doping lithium, or transition metal oxides.

[0138] Materials that reversibly intercalate / deintercalate lithium ions can include carbonaceous negative electrode active materials, e.g., crystalline carbon, amorphous carbon, and / or their (e.g., any suitable) combination. The crystalline carbon can be graphite, such as amorphous (e.g., having an irregular shape), flaky, lamellar, spherical, or fibrous natural graphite or artificial graphite, and the amorphous carbon can be soft carbon, hard carbon, mesophase pitch carbonization products, calcined coke, etc.

[0139] Lithium metal alloys include alloys of lithium with metals selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0140] Materials capable of doping / de-doping lithium can be Si-based negative electrode active materials or Sn-based negative electrode active materials. Si-based negative electrode active materials can include silicon, silicon-carbon composites, SiO x (0 < x ≤ 2), Si-Q alloys (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 / or their (e.g., any suitable) combination). Sn-based negative electrode active materials can include Sn, SnO x (0 < x ≤ 2, e.g., SnO 2 )、Sn-based alloys and / or their (e.g., any suitable) combination.

[0141] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one or more 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.

[0142] 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.

[0143] Si-based negative electrode active materials or Sn-based negative electrode active materials may be used in combination with carbon-based negative electrode active materials.

[0144] Negative electrode

[0145] 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.

[0146] For example, based on about 100 wt% of the negative electrode active material layer, 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.

[0147] The binder is used to attach (e.g., well attach) the negative electrode active material particles to each other and is also used to attach (e.g., well attach) the negative electrode active material to the negative electrode current collector. The binder may include a non-aqueous binder, an aqueous binder, a dry binder, and / or a combination thereof (e.g., any suitable combination).

[0148] 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, and / or a combination thereof (e.g., any suitable combination).

[0149] The aqueous binder may be selected from styrene-butadiene rubber, (meth)acrylate esterified styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, epichlorohydrin rubber, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and / or a combination thereof (e.g., any suitable combination).

[0150] When an aqueous binder is used as a binder in the negative electrode active material layer, a cellulose compound capable of imparting viscosity may be further included. The cellulose compound may include at least one of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and its alkali metal salts. The alkali metal may include Na, K, or Li.

[0151] The dry binder may be a polymer material capable of being fibrillated and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride - hexafluoropropylene copolymer, polyethylene oxide, and / or a combination thereof (e.g., any suitable combination).

[0152] The conductive material is used to impart conductivity to the electrode, and any suitable material that does not cause a chemical change and conducts electrons can be used in the battery. Examples thereof may include carbon materials (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and / or carbon nanotube); metal materials including copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fiber; conductive polymers (such as polyphenylene derivatives); and / or a mixture (combination) thereof (e.g., any suitable combination).

[0153] The negative electrode current collector may include a copper foil, a nickel foil, a stainless - steel foil, a titanium foil, a nickel foam, a copper foam, a polymer substrate coated with a conductive metal, and / or a combination thereof (e.g., any suitable combination).

[0154] Separator

[0155] 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 of them (such as a polyethylene / polypropylene two - layer separator, a polyethylene / polypropylene / polyethylene three - layer separator, a polypropylene / polyethylene / polypropylene three - layer separator, etc.).

[0156] The separator may include a porous substrate and a coating on (e.g., one or two surfaces (e.g., opposite surfaces or sides)) of the porous substrate, and the coating includes an organic material, an inorganic material, and / or a combination thereof (e.g., any suitable combination).

[0157] The porous substrate may be a polymer film formed from any one selected from polyolefins (such as polyethylene and / or polypropylene), polyesters (such as polyethylene terephthalate and / or polybutylene terephthalate), polyacetals, polyamides, polyimides, polycarbonates, polyether ketones, polyarylether ketones, polyetherimides, polyamideimides, polybenzimidazoles, polyethersulfones, polyphenylene ethers, cycloolefin copolymers, polyphenylene sulfides, polyethylene naphthalate, glass fiber, and polytetrafluoroethylene (e.g., Teflon), or a copolymer or mixture of two or more of them.

[0158] The organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic acid-based polymer.

[0159] The inorganic material may include selected from Al 2 O 3 , SiO 2 , TiO 2 , SnO 2 , CeO 2 , MgO, NiO, CaO, GaO, ZnO, ZrO 2 , Y 2 O 3 , SrTiO 3 , BaTiO 3 , Mg(OH) 2 , boehmite and / or inorganic particles of its (e.g., any suitable) combination, but the present disclosure is not limited thereto.

[0160] The organic material and the inorganic material may be mixed in one coating, or a coating including (e.g., only) the organic material and a coating including (e.g., only) the inorganic material may be stacked.

[0161] Embodiments and comparative examples of the present disclosure are described in more detail below. However, the following embodiments are only examples of the present disclosure, and the present disclosure is not limited to the following embodiments.

[0162] (Example)

[0163] Example 1

[0164] 1.15 M of LiPF as a lithium salt 6 was dissolved in a non-aqueous organic solvent mixed with ethylene carbonate (EC), ethyl methyl carbonate (MEC), and diethyl carbonate (DEC) in a volume ratio of 20:40:40 to prepare a base electrolyte.

[0165] A first compound represented by Compound 1-a and a second compound represented by Chemical Formula 2-2 were added to the base electrolyte to prepare an electrolyte according to Example 1.

[0166] Compound 1-a

[0167]

[0168] Chemical Formula 2-2

[0169]

[0170] In the electrolyte, based on the total weight of the electrolyte, the first compound was included at 2 wt% and the second compound was included at 0.5 wt%.

[0171] LiNi which serves as the positive electrode active material 0.91 Co 0.07 Al 0.02 O 2 , polyvinylidene fluoride which serves as the binder, and Ketjen black which serves as the conductive material are mixed at a weight ratio of 97:2:1, and then dispersed in N-methylpyrrolidone to prepare the positive electrode active material paste.

[0172] The positive electrode active material paste is coated on a 14-μm-thick Al foil, dried and pressed at 110 °C to fabricate the positive electrode.

[0173] In addition, the negative electrode active material paste is prepared as follows: artificial graphite which serves as the negative electrode active material, styrene-butadiene rubber which serves as the binder, and carboxymethyl cellulose which serves as the thickener are mixed at a weight ratio of 97:1:2, and the mixture is dispersed in distilled water. The negative electrode active material paste is coated on a 10-μm-thick Cu foil current collector, dried at 100 °C, and pressed to fabricate the negative electrode.

[0174] A 25-μm-thick separator having a polyethylene-polypropylene multilayer structure is disposed between the positive electrode and the negative electrode to fabricate an electrode assembly, and a rechargeable lithium battery cell (57 Ah) is fabricated by inserting the electrode assembly into a prismatic battery case and injecting the prepared electrolyte into it.

[0175] Example 2

[0176] A rechargeable lithium battery cell is fabricated in substantially the same manner as in Example 1, except that the compound represented by Chemical Formula 2-1 is used as the second compound.

[0177] Chemical Formula 2-1

[0178]

[0179] Examples 3 to 14

[0180] Each rechargeable lithium battery cell is fabricated in substantially the same manner as in Example 1, except that the contents of the first compound and the second compound are changed as shown in Table 1 based on the total weight of the electrolyte.

[0181] Examples 15 to 19

[0182] Each rechargeable lithium battery cell is fabricated in substantially the same manner as in Example 2, except that the contents of the first compound and the second compound are changed as shown in Table 1 based on the total weight of the electrolyte.

[0183] Comparative Example 1

[0184] A rechargeable lithium battery cell was fabricated in substantially the same manner as in Example 1, except that the first compound and the second compound were not added to the electrolyte solution.

[0185] Comparative Example 2

[0186] A rechargeable lithium battery cell was fabricated in substantially the same manner as in Example 1, except that the second compound was not added to the electrolyte solution.

[0187] Comparative Example 3

[0188] A rechargeable lithium battery cell was fabricated in substantially the same manner as in Example 1, except that the first compound was not added to the electrolyte solution.

[0189] Comparative Example 4

[0190] A rechargeable lithium battery cell was fabricated in substantially the same manner as in Example 2, except that the first compound was not added to the electrolyte solution.

[0191] Table 1

[0192]

[0193]

[0194] Evaluation Example

[0195] Evaluation Example 1: Evaluation of Overcharge / Quick Charge Safety

[0196] The overcharge safety of rechargeable lithium battery cells according to some embodiments (Examples 1 to 2, Examples 4 to 8, Examples 10 to 13, and Examples 15 to 18) and Comparative Examples 1 to 4 was evaluated, and the results are shown in Table 2.

[0197] After attaching a safety protection device to the negative electrode of each rechargeable lithium battery cell by welding and attaching a tab to the positive electrode of each rechargeable lithium battery cell by welding, a thermocouple was attached and fixed to the center of the cell to measure the temperature.

[0198] Subsequently, the cell was charged at a rate of 1.0C to 6V and subjected to this voltage for 50 minutes to overcharge / quick charge the cell.

[0199] If the cell did not catch fire during the period of being subjected to the test but was in substantially the same state as before the evaluation, "Pass" was given, and if the cell caught fire, "Fail" was given, as shown in Table 2.

[0200] In addition, the overcharge evaluation results of the rechargeable lithium battery cells of Examples 1 to 2 and Comparative Examples 1 to 4 are as Figure 5as shown in the graph in

[0201] In Figure 5 it, the curve relatively located at the top represents the change of voltage over time, while the curve relatively located at the bottom represents the change of temperature over time.

[0202] Evaluation Example 2: Evaluation of Room Temperature Cycle Life Characteristics

[0203] Evaluate the cycle life characteristics of rechargeable lithium battery cells according to some embodiments (Embodiment 1 to Embodiment 2, Embodiment 4 to Embodiment 8, Embodiment 10 to Embodiment 13, and Embodiment 15 to Embodiment 18) and Comparative Examples 1 to 4 at room temperature (25 °C).

[0204] For example, the battery cells are charged at 0.05C in the range of 2.8V to 4.2V and discharged at 0.5C for 465 cycles to calculate the ratio of the discharge capacity at the 465th cycle to the discharge capacity at the 1st cycle (i.e., the capacity retention rate (%)), and the results are shown in Table 2.

[0205] In addition, the evaluation results of the room temperature cycle life characteristics of the rechargeable lithium battery cells of Embodiment 1 to Embodiment 2 and Comparative Examples 1 to 4 are as Figure 6 shown in the graph in

[0206] Table 2

[0207]

[0208] Referring to Table 2, the battery cells of Comparative Example 1, Comparative Example 3, and Comparative Example 4 (which do not include the first compound in the electrolyte) catch fire if (e.g., when) overcharged.

[0209] In addition, referring to Figure 5 , even after being overcharged for 50 minutes, the battery cells of Embodiment 1 and Embodiment 2 maintain a substantially constant battery temperature, while the battery cells of Comparative Example 1, Comparative Example 3, and Comparative Example 4 show that the battery temperature rises to about 400 °C at about 35 minutes.

[0210] Referring to Table 2 and Figure 6 , as described above, the embodiments exhibit excellent or appropriate overcharge characteristics and room temperature cycle life characteristics comparable to those of the comparative examples.

[0211] In the context of the present application and unless otherwise defined, the terms "use", "using", and "used" may be regarded as synonymous with the terms "utilize", "utilizing", and "utilized", respectively.

[0212] When describing embodiments of the inventive concept, the use of "may" refers to "one or more embodiments of the inventive concept".

[0213] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Throughout the present disclosure, expressions such as "at least one selected from a, b, and c", "at least one selected from the group consisting of a, b, and c" ("at least one selected from a,b,and c"), "at least one of a, b, and c", "at least one selected from among a, b, and c" ("at least one selected from among a,b,and c"), etc. indicate only a, only b, only c, both a and b (e.g., simultaneously), both a and c (e.g., simultaneously), both b and c (e.g., simultaneously), all of a, b, and c, or variations thereof.

[0214] As used herein, the terms "about" and similar terms are used as approximate terms and not as terms of degree, and are intended to account for the inherent deviations of measured or calculated values that would be recognized by a person of ordinary skill in the art. As used herein, "about" includes the recited value and means within an acceptable deviation range of a particular value determined by a person of ordinary skill in the art in view of the measurements discussed and the errors associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, "about" may refer to within one or more standard deviations, or within ±30%, ±20%, ±10%, or ±5% of the recited value.

[0215] Also, any numerical range set forth herein is intended to include all sub-ranges of the same numerical precision falling within the set forth range. For example, the range "1.0 to 10.0" is intended to include between the recited minimum value of 1.0 and the recited maximum value of 10.0 (and including 1.0 and 10.0), i.e., all sub-ranges having 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 to 7.6). Any maximum numerical limit set forth herein is intended to include all lower numerical limits falling therein, and any minimum numerical limit set forth in this specification is intended to include all higher numerical limits falling therein. Accordingly, the applicant reserves the right to amend this specification (including the claims) to expressly recite any sub-ranges falling within the ranges expressly set forth herein.

[0216] The battery management system (BMS) device and / or any other relevant devices or components according to embodiments of the present invention described herein may be implemented using any suitable hardware, firmware (e.g., application specific integrated circuit), software, or a combination of software, firmware, and hardware. For example, the various components of the device may be formed on one integrated circuit (IC) chip or separate IC chips. Further, the various components of the device may be implemented on a flexible printed circuit membrane, tape carrier package (TCP), or printed circuit board (PCB), or formed on a substrate. Further, the various components of the device may be processes or threads running on one or more processors in one or more computing devices, executing computer program instructions and interacting with other system components to perform the various functions described herein. The computer program instructions are stored in a memory, which may be implemented using standard memory devices (such as, for example, random access memory (RAM)) in the computing device. The computer program instructions may also be stored in other non-transitory computer-readable media (such as, for example, CD-ROM, flash drive, etc.). And, 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 over one or more other computing devices.

[0217] Although the present disclosure has been described in connection with what are presently considered to be example embodiments in practice, it is to be understood that the present disclosure is not limited to the disclosed embodiments. On the contrary, the present disclosure is intended to cover one or more suitable modifications and equivalent arrangements included within the spirit and scope of the claims and their equivalents.

Claims

1. An electrolyte comprising: Non-aqueous organic solvents; Lithium salts; and additive, The additive includes a first compound represented by Chemical Formula 1 and a second compound represented by Chemical Formula 2: Chemical formula 1 Chemical formula 2 Wherein, in Chemical Formula 1, R 1 and R 2 are each independently a substituted or unsubstituted C1-C20 alkyl group or a substituted or unsubstituted C6-C30 aryl group, provided that R 1 and R 2 At least one of them is a substituted or unsubstituted C6-C30 aryl group, In chemical formula 2, M is boron or phosphorus, R 3 and R 4 are each independently hydrogen, halogen, or substituted or unsubstituted C1-C10 alkyl, R 5 is a substituted or unsubstituted methylene group, n is an integer from 1 to 3, m is 0 or 1, m1 and m2 are each independently an integer from 0 to 2, and The electrolyte is used in a rechargeable lithium battery.

2. The electrolyte according to claim 1, wherein The first compound represented by Chemical Formula 1 is represented by Chemical Formula 1-1 or Chemical Formula 1-2: Chemical formula 1-1 In Chemical Formula 1-1, R 1a is a substituted or unsubstituted C1-C20 alkyl group, and H a ~H e Each is independently hydrogen, halogen, hydroxyl, cyano, nitro, 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; Chemical formula 1-2 and In Chemical Formula 1-2, H a ~H j Each is independently hydrogen, halogen, hydroxyl, cyano, nitro, 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.

3. The electrolyte according to claim 1, wherein The first compound includes one or more compounds selected from the group consisting of: Group 1 4. The electrolyte according to claim 1, wherein The second compound represented by Chemical Formula 2 includes one or more compounds selected from the group consisting of compounds represented by Chemical Formula 2-1 to Chemical Formula 2-8: Chemical formula 2-1 Chemical formula 2-2 Chemical formula 2-3 Chemical formula 2-4 Chemical formula 2-5 Chemical formula 2-6 Chemical formula 2-7 Chemical formula 2-8 5. The electrolyte according to claim 1, wherein The lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N, LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate or a combination thereof, wherein x and y are each independently an integer selected from 1 to 20.

6. The electrolyte according to claim 1, wherein Based on the total weight of the electrolyte, the amount of the first compound is greater than 0.05 wt % and less than 10 wt %.

7. The electrolyte according to claim 1, wherein Based on the total weight of the electrolyte, the amount of the second compound is greater than 0.05 wt % and less than 5 wt %.

8. The electrolyte according to claim 1, wherein The weight ratio of the first compound to the second compound is 0.05:1 to 50:

1.

9. A rechargeable lithium battery comprising: a positive electrode, including a positive electrode active material; a negative electrode, including a negative electrode active material; a separator between the positive electrode and the negative electrode; as well as The electrolyte according to any one of claims 1 to 8.

Images