Electrolyte additive for rechargeable lithium battery, electrolyte including same, and rechargeable lithium battery including electrolyte

Abstract

The invention relates to an electrolyte additive for a rechargeable lithium battery, an electrolyte including the same, and a rechargeable lithium battery including the electrolyte. The electrolyte additive for a rechargeable lithium battery includes a polymer obtained by polymerizing a first compound represented by Chemical Formula 1, Chemical Formula 2, or Chemical Formula 3 as a monomer; and a second compound represented by Chemical Formula 4.

Description

Technical Field

[0001] Embodiments of the present disclosure described herein relate to an electrolyte additive for a rechargeable lithium battery, an electrolyte including the same, and a rechargeable lithium battery including the electrolyte. Background Art

[0002] Rechargeable lithium batteries are rechargeable and have an energy density per unit weight that is three or more times higher than the energy density per unit weight of comparable lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, etc. Rechargeable lithium batteries can also be charged at relatively high rates and, therefore, are commercially manufactured for use in laptop computers, cellular phones, power tools, electric bicycles, vehicles (e.g., electric cars, electric bicycles, etc.), etc., and additional energy density improvements have been studied and / or sought.

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

[0004] For example, the electrolyte includes a non-aqueous organic solvent in which a lithium salt is dissolved, and may determine thermal stability and performance of a rechargeable lithium battery.

[0005] LiPF6 can be used as a lithium salt of an electrolyte, but has the problem of reacting with a non-aqueous organic solvent of the electrolyte, causing consumption of the non-aqueous organic solvent and generating a large amount of gas. For example, when LiPF6 decomposes, LiF and PF5 are generated, which causes consumption of the electrolyte in a rechargeable lithium battery, leading to performance degradation under relatively high temperature conditions, and easily causing safety problems.

[0006] Accordingly, there is a need or desire for an electrolyte having improved safety without deteriorating performance even under relatively high temperature conditions, and these problems are being addressed or studied by introducing one or more appropriate additives into the electrolyte. Summary of the invention

[0007] Aspects according to one or more embodiments relate to an electrolyte additive for a rechargeable lithium battery having improved thermal stability by inhibiting or reducing explosion and ignition if the rechargeable lithium battery is exposed to a relatively high temperature (e.g., when the rechargeable lithium battery is exposed to a relatively high temperature), and preventing or reducing a temperature increase of the rechargeable lithium battery.

[0008] Aspects according to one or more embodiments relate to an electrolyte for a rechargeable lithium battery that improves the thermal stability of a rechargeable lithium battery by inhibiting or reducing explosion and ignition if the rechargeable lithium battery is exposed to a relatively high temperature (e.g., when the rechargeable lithium battery is exposed to a relatively high temperature), and preventing or reducing an increase in the temperature of the rechargeable lithium battery.

[0009] Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the presented embodiments of the disclosure.

[0010] According to one or more embodiments, an electrolyte additive for a rechargeable lithium battery includes a polymer obtained by polymerizing a first compound represented by Chemical Formula 1, a first compound represented by Chemical Formula 2, or a first compound represented by Chemical Formula 3 as a monomer; and a second compound represented by Chemical Formula 4.

[0011] Chemical formula 1

[0012]

[0013] Chemical formula 2

[0014]

[0015] Chemical formula 3

[0016]

[0017] Chemical formula 4

[0018]

[0019] In Chemical Formula 1, R1 is a substituted or unsubstituted C1-C4 alkylene, -C(O)CH2-, -ROR'OR-, -CH2OCH2-, -C(O)-, -O-, -OO-, -S-, -SS-, -S(O)-, -CH2S(O)CH2-, -(O)S(O)-, -CH2(C6H4)CH2-, -CH2(C6H4)O-, a substituted or unsubstituted phenylene, or a substituted or unsubstituted biphenylene, wherein R is a C1-C4 alkylene and R' is a C1-C4 alkylene,

[0020] In Chemical Formula 2, R2 is a substituted or unsubstituted C1-C4 alkylene group, -C(O)-, -C(CH3)2-, -O-, -OO-, -S-, -SS-, -(O)S(O)- or -S(O)-,

[0021] In Chemical Formula 3, R3 to R7 may each independently be hydrogen, halogen, substituted or unsubstituted C1 to C6 alkyl, substituted or unsubstituted C2 to C6 alkenyl, substituted or unsubstituted C6 to C10 aryl, substituted or unsubstituted C2 to C6 ether, or substituted or unsubstituted C1 to C6 alkoxy.

[0022] In chemical formula 4, R8~R 10 may be independently hydrogen; cyano; halogen; substituted or unsubstituted C1-C10 hydrocarbon group including C1-C10 alkyl, C3-C10 cycloalkyl, C1-C10 alkoxy, C1-C10 carboxyl or hydroxyl; R a C(=O)-;R b C(=O)O-; or R c N(H)C(=O)-, and

[0023] R8~R 10 Each may be present independently, or at least two of them may be linked to form (or provide) a substituted or unsubstituted C4-C10 monocyclic aliphatic ring or a C4-C10 polycyclic aliphatic ring.

[0024] R a , R b and R c Each is independently a substituted or unsubstituted C1-C10 alkyl group.

[0025] According to one or more embodiments, an electrolyte for a rechargeable lithium battery according to one or more embodiments includes a non-aqueous organic solvent, a lithium salt, and an electrolyte additive for a rechargeable lithium battery.

[0026] According to 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 an electrolyte for a rechargeable lithium battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram illustrating a rechargeable lithium battery according to one or more embodiments.

[0028] Figure 2 Graphs showing temperature changes and voltage changes according to heat exposure at about 143° C. of the rechargeable lithium battery cells according to Comparative Examples 1, 3, and 7, and Examples 6 and 10.

[0029] Figure 3 is a graph showing the capacity retention rate (%) of the rechargeable lithium battery cells according to Example 1, Example 3, and Example 10 at a relatively high temperature.

[0030] Figure 4 FIG. 1 is a graph showing capacity recovery rates (%) of rechargeable lithium battery cells according to Example 1, Example 3, and Example 10 at relatively high temperatures.

[0031] Figure 5 Graph showing the increase rate (%) of the DC internal resistance of the rechargeable lithium battery cells according to Example 1, Example 3 and Example 10 at a relatively high temperature.

[0032] Figure 6 Graph showing the open circuit voltage change rate (%) of the rechargeable lithium battery cells according to Example 1, Example 3, and Example 10 at a relatively high temperature.

[0033] Figure 7 is a graph showing capacity retention rates (%) of rechargeable lithium battery cells according to Example 1, Example 3, and Example 10 at room temperature.

[0034] Reference numerals

[0035] 100: Rechargeable lithium battery 112: Negative electrode

[0036] 113: separator 114: positive electrode

[0037] 120: Battery case 140: Sealing member DETAILED DESCRIPTION

[0038] Hereinafter, specific embodiments will be described in more detail so that those skilled in the art can easily implement them. However, the present disclosure may be embodied in many different forms and is not to be construed as limited to the example embodiments set forth herein.

[0039] The terms utilized herein are only used to describe the embodiments and are not intended to limit the present disclosure. Unless the context clearly indicates otherwise, a singular expression also includes a plural expression.

[0040] As utilized herein, "combinations thereof" refers to mixtures, laminates, composites, copolymers, alloys, blends, reaction products, and the like, of the components.

[0041] In this document, it should be understood that terms such as “comprises,” “includes,” or “have” are intended to mark the presence of specified features, quantities, operations, elements, and / or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, quantities, operations, elements, and / or combinations thereof.

[0042] In the accompanying drawings, for the sake of clarity, the thickness of layers, films, panels, regions, etc. is exaggerated, and the same reference numerals are used throughout to mark the same elements, and their repeated descriptions may not be provided in the specification. It will be understood that if 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) (for example, 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 may be directly on another element (such as a layer, film, region, or substrate), or there may also be an intervening element (such as a layer, film, region, or substrate). In contrast, if an element (such as a layer, film, region, or substrate) is referred to as being "directly on" another element (such as a layer, film, region, or substrate) (for example, when an element (such as a layer, film, region, or substrate) is referred to as being "directly on" another element (such as a layer, film, region, or substrate) "on"), there is no intervening element (such as a layer, film, region, or substrate).

[0043] In one or more embodiments, the “layer” herein includes not only a shape formed on the entire surface if viewed from a plan view (for example, when viewed from a plan view) but also a shape formed on a partial surface.

[0044] In one or more embodiments, the average particle size can be measured by a method suitable for those skilled in the art, for example, the average particle size can be measured by a particle size analyzer or can be measured by a transmission electron micrograph or a scanning electron micrograph. In one or more embodiments, the average particle size value can be obtained by measuring using a dynamic light scattering method, performing data analysis, counting the number of particles in each particle size range, and calculating therefrom. The average particle size (D) can be measured by a microscope image or a particle size analyzer. 50 ), and may refer to the diameter of particles accounting for 50% by volume of the cumulative volume in a particle size distribution.

[0045] In this document, “or” is not interpreted as being exclusive. For example, “A or B” is interpreted as including A, B, A+B, etc.

[0046] As utilized herein, expressions such as “at least one of,” “one of,” and “(e.g., selected from) of,” when preceding / following a list of elements, modify the entire list of elements and do not modify the individual elements of the list. For example, “at least one of a, b, and c,” “at least one selected from a, b, and c,” and the like may indicate only a, only b, only c, both a and b (e.g., a and b simultaneously), both a and c (e.g., a and c simultaneously), both b and c (e.g., b and c simultaneously), all of a, b, and c, or variations thereof.

[0047] The terms used in this article are only intended to describe specific embodiments and are not intended to limit the present disclosure. As used in this article, unless otherwise clearly indicated content (e.g., amount), the singular forms "a", "an", and "said" are intended to include plural forms (including "at least one"). "At least one" should not be interpreted as being limited to the singular. As used in this article, the term "and / or" includes any and all combinations of one or more related enumerated items. The terms "includes", "including", "comprises", and / or "comprising", when used in the detailed description, indicate the presence of narrated features, regions, integers, steps, operations, elements, components, and / or groups thereof, but do not exclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and / or groups thereof.

[0048] Spatially relative terms, such as "below," "below," "below," "above," and "on," may be used herein to easily describe the relationship of one element or feature to another element or feature. It will be understood that in addition to the orientations illustrated in the drawings, the spatially relative terms are intended to encompass different orientations of the device in use or operation. For example, when the device in the drawings is turned over, elements described as being "below" or "below" other elements or features will then be "above" or "on" the other elements or features. In some embodiments, the example term "below" may encompass both the orientation above and the orientation below (e.g., both the orientation above and the orientation below). The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative terms utilized herein may be interpreted accordingly.

[0049] As utilized herein, the term "metal" includes all metals and metalloids (such as silicon and germanium) in either elemental or ionic form.

[0050] As utilized herein, the term "alloy" refers to a mixture of two or more metals.

[0051] As utilized herein, the term "electrode active material" refers to an electrode material that can undergo lithiation and delithiation.

[0052] As utilized herein, the term "positive electrode active material" refers to a positive electrode material that can undergo lithiation and delithiation.

[0053] As utilized herein, the term "negative electrode active material" refers to a negative electrode material that can undergo lithiation and delithiation.

[0054] As utilized herein, the terms "lithiate" and "lithiating" refer to the process of adding lithium to an electrode active material.

[0055] As utilized herein, the terms "delithiate" and "delithiating" refer to the process of removing lithium from an electrode active material.

[0056] As utilized herein, the terms "charge" and "charging" refer to the process of providing electrochemical energy to a rechargeable lithium battery.

[0057] As utilized herein, the terms "discharge" and "discharging" refer to the process of removing electrochemical energy from a rechargeable lithium battery.

[0058] As utilized herein, the terms "positive electrode" and "cathode" refer to the electrode that undergoes electrochemical reduction and lithiation during the discharge process.

[0059] As utilized herein, the terms "negative electrode" and "anode" refer to the electrode at which electrochemical oxidation and delithiation occur during the discharge process.

[0060] As utilized herein, the term "substantially" and similar terms are used as terms of approximation and not as terms of degree, and are intended to take into account the inherent deviations in measured or calculated values ​​that one of ordinary skill in the art would recognize. Also, when utilized herein in conjunction with a numerical value or range of values, the term "about" and similar terms include the recited value and values ​​within an acceptable range of deviations of the particular value determined by one of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of the particular quantity (e.g., limitations of the measurement system). For example, "about" may mean within one or more standard deviations of the recited value, or within ±30%, ±20%, ±10%, or ±5% of the recited value.

[0061] Furthermore, any numerical range set forth in this article is intended to include all sub-ranges of the same numerical precision falling within the range set forth. For example, the range of "1.0-10.0" is intended to be included between the minimum value of 1.0 set forth and the maximum value of 10.0 set forth (and including 1.0 and 10.0), that is, all sub-ranges with a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as, for example, 2.4-7.6. Any maximum numerical limit set forth in this article 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 modify this specification, including the claims, to explicitly set forth any sub-range falling within the range explicitly set forth in this article.

[0062] As utilized herein, if no specific limitations are otherwise provided (e.g., when no specific limitations are otherwise provided), "substituted" refers to replacement of at least one hydrogen of a substituent or a compound with 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 and / or combinations thereof.

[0063] For example, "substituted" means that at least one hydrogen of a substituent or compound is 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" means that at least one hydrogen of a substituent or compound is replaced by deuterium, halogen, C1-C20 alkyl, C6-C30 aryl, C1-C10 fluoroalkyl or cyano. For example, "substituted" means that at least one hydrogen of a substituent or compound is replaced by deuterium, halogen, C1-C5 alkyl, C6-C18 aryl, C1-C5 fluoroalkyl or cyano. For example, "substituted" means that at least one hydrogen of the substituent or compound is replaced by deuterium, cyano, halogen, methyl, ethyl, propyl, butyl, phenyl, biphenyl, terphenyl, trifluoromethyl, or naphthyl.

[0064] Electrolyte additives for rechargeable lithium batteries

[0065] The electrolyte additive for a rechargeable lithium battery includes a polymer obtained by polymerizing a first compound represented by Chemical Formula 1, a first compound represented by Chemical Formula 2, or a first compound represented by Chemical Formula 3 as a monomer; and a second compound represented by Chemical Formula 4.

[0066] The electrolyte additive for a rechargeable lithium battery according to one or more embodiments includes: a polymer including a first compound (as a monomer) and both a second compound (e.g., a polymer including the first compound (as a monomer) and the second compound at the same time), thereby rapidly increasing the viscosity of the electrolyte at a relatively high temperature of about 100° C. As a result, at a relatively high temperature, the ion conductivity of the electrolyte is rapidly reduced, thereby shutting down the rechargeable lithium battery, which has the advantages of suppressing or reducing explosion and ignition of the rechargeable lithium battery and preventing or reducing an increase in the temperature of the rechargeable lithium battery.

[0067] First Compound

[0068] The first compound includes a maleimide group at the terminal end The present invention is a maleimide compound and is a free radical polymerizable monomer including an unsaturated bond capable of free radical polymerization at the terminal.

[0069] The polymer may be formed (or provided) by initiating a free radical polymerization reaction of the first compound with a second compound which will be described in more detail later.

[0070] As an example, the compound represented by Chemical Formula 1 or Chemical Formula 2 is a bismaleimide-based compound including maleimide groups at both ends (eg, opposite ends).

[0071] The first compound is represented by Chemical Formula 1, Chemical Formula 2, or Chemical Formula 3.

[0072] Chemical formula 1

[0073]

[0074] In Chemical Formula 1, R1 is substituted or unsubstituted C1~C4 alkylene, -C(O)CH2-, -ROR'OR-, -CH2OCH2-, -C(O)-, -O-, -OO-, -S-, -SS-, -S(O)-, -CH2S(O)CH2-, -(O)S(O)-, -CH2(C6H4)CH2-, -CH2(C6H4)O-, substituted or unsubstituted phenylene or substituted or unsubstituted biphenylene, wherein R is C1~C4 alkylene and R' is C1~C4 alkylene.

[0075] For example, R1 may be -ROR'OR-, -CH2OCH2-, substituted or unsubstituted phenylene or substituted or unsubstituted biphenylene, and as the most specific example, R1 may be substituted or unsubstituted phenylene or substituted or unsubstituted biphenylene, wherein R may be a C1~C4 alkylene and R' may be a C1~C4 alkylene.

[0076] The first compound represented by Chemical Formula 1 may include one or more compounds selected from the group consisting of compounds represented by Chemical Formula 1A to Chemical Formula 1E.

[0077] Chemical formula 1A

[0078]

[0079] Chemical formula 1B

[0080]

[0081] Chemical formula 1C

[0082]

[0083] Chemical formula 1D

[0084]

[0085] Chemical formula 1E

[0086]

[0087] Chemical formula 2

[0088]

[0089] In Chemical Formula 2, R2 is a substituted or unsubstituted C1~C4 alkylene group, -C(O)-, -C(CH3)2-, -O-, -OO-, -S-, -SS-, -(O)S(O)- or -S(O)-.

[0090] For example, R2 may be a substituted or unsubstituted C1-C4 alkylene group, -C(O)- or -C(CH3)2-.

[0091] The first compound represented by Chemical Formula 2 may include one or more compounds selected from the group consisting of compounds represented by Chemical Formula 2A to Chemical Formula 2C.

[0092] Chemical formula 2A

[0093]

[0094] Chemical formula 2B

[0095]

[0096] Chemical formula 2C

[0097]

[0098] Chemical formula 3

[0099]

[0100] In Chemical Formula 3, R3 to R7 may each independently be hydrogen, halogen, substituted or unsubstituted C1 to C6 alkyl, substituted or unsubstituted C1 to C6 alkenyl, substituted or unsubstituted C6 to C10 aryl, substituted or unsubstituted C2 to C6 ether, or substituted or unsubstituted C1 to C6 alkoxy.

[0101] For example, R3 to R7 may each independently be hydrogen, halogen, or a substituted or unsubstituted C1 to C6 alkoxy group.

[0102] The first compound represented by Chemical Formula 3 may include one or more compounds selected from the group consisting of compounds represented by Chemical Formulas 3A to 3C.

[0103] Chemical formula 3A

[0104]

[0105] Chemical formula 3B

[0106]

[0107] Chemical formula 3C

[0108]

[0109] Second compound

[0110] The second compound is an initiator of radical polymerization, and is a compound having a nitrogen-nitrogen double bond (—N═N—) at the center of the compound.

[0111] The second compound is represented by Chemical Formula 4.

[0112] Chemical formula 4

[0113]

[0114] In chemical formula 4, R8~R 10 may be independently hydrogen; cyano; halogen; substituted or unsubstituted C1-C10 hydrocarbon group including C1-C10 alkyl, C3-C10 cycloalkyl, C1-C10 alkoxy, C1-C10 carboxyl or hydroxyl; R a C(=O)-;R b C(=O)O-; or R c N(H)C(=O)-, and

[0115] R8~R 10 Each may be present independently, or at least two of them may be linked to form (or provide) a substituted or unsubstituted C4-C10 monocyclic aliphatic ring or a C4-C10 polycyclic aliphatic ring.

[0116] R a , R b and R c Each is independently a substituted or unsubstituted C1-C10 alkyl group. a , R b and R cEach may independently be a C1-C10 alkyl substituted 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 and / or combinations thereof.

[0117] When the activation energy ray is irradiated to the second compound, nitrogen (N2) and two molecules including free radicals (2 ). The molecule having a free radical initiates a radical polymerization reaction of an unsaturated bond located at a terminal of the first compound, thereby producing a polymer using the first compound as a monomer.

[0118] As an example, the second compound represented by Chemical Formula 4 may include one or more compounds selected from the compounds listed in Group 1. The compounds listed in Group 1 are wherein R8 to R 10 A compound wherein any one of the groups is a cyano group.

[0119] Group 1

[0120]

[0121]

[0122] As an example, the second compound represented by Chemical Formula 4 may include one or more compounds selected from the compounds listed in Group 2.

[0123] Group 2

[0124]

[0125] The weight ratio of the first compound to the second compound can be, for example, about 2:1 to about 10000:1, about 3:1 to about 10000:1, about 3:1 to about 1000:1, about 3:1 to about 1000:1, about 3:1 to about 500:1, about 3:1 to about 100:1, about 3:1 to about 50:1, about 3:1 to about 40:1, or about 3:1 to about 30:1.

[0126] When the weight ratio is within the above range, thermal stability of the rechargeable lithium battery may be significantly improved.

[0127] Other additives

[0128] In addition to the above-mentioned additives, the electrolyte may further include other additives. If the other additives are combined with the first compound and the second compound (eg, when the other additives are combined with the first compound and the second compound), a synergistic effect may be generated.

[0129] Other additives may include one or more selected from vinylene carbonate (VC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), chloroethylene carbonate (CEC), dichloroethylene carbonate (DCEC), brominated ethylene carbonate (BEC), dibromoethylene carbonate (DBEC), nitroethylene carbonate, cyanoethylene carbonate, vinylethylene carbonate (VEC), succinonitrile (SN), adiponitrile (AN), 1,3,6-hexanetrinitrile (HTCN), propene sultone (PST), propane sultone (PS), lithium tetrafluoroborate (LiBF4), lithium difluorophosphate (LiPO2F2) and 2-fluorobiphenyl (2-FBP), but are not limited thereto.

[0130] Electrolyte

[0131] An electrolyte for a rechargeable lithium battery includes a non-aqueous organic solvent, a lithium salt, and an electrolyte additive for a rechargeable lithium battery, the electrolyte additive for a rechargeable lithium battery including a polymer obtained by polymerizing a first compound represented by Chemical Formula 1, a first compound represented by Chemical Formula 2, or a first compound represented by Chemical Formula 3 as a monomer; and a second compound represented by Chemical Formula 4.

[0132] Chemical formula 1

[0133]

[0134] Chemical formula 2

[0135]

[0136] Chemical formula 3

[0137]

[0138] Chemical formula 4

[0139]

[0140] In Chemical Formula 1, R1 is a substituted or unsubstituted C1-C4 alkylene, -C(O)CH2-, -ROR'OR-, -CH2OCH2-, -C(O)-, -O-, -OO-, -S-, -SS-, -S(O)-, -CH2S(O)CH2-, -(O)S(O)-, -CH2(C6H4)CH2-, -CH2(C6H4)O-, a substituted or unsubstituted phenylene, or a substituted or unsubstituted biphenylene, wherein R is a C1-C4 alkylene and R' is a C1-C4 alkylene,

[0141] In Chemical Formula 2, R2 is a substituted or unsubstituted C1-C4 alkylene group, -C(O)-, -C(CH3)2-, -O-, -OO-, -S-, -SS-, -(O)S(O)- or -S(O)-,

[0142] In Chemical Formula 3, R3 to R7 may each independently be hydrogen, halogen, substituted or unsubstituted C1 to C6 alkyl, substituted or unsubstituted C2 to C6 alkenyl, substituted or unsubstituted C6 to C10 aryl, substituted or unsubstituted C2 to C6 ether, or substituted or unsubstituted C1 to C6 alkoxy.

[0143] In chemical formula 4, R8~R 10 may be independently hydrogen; cyano; halogen; substituted or unsubstituted C1-C10 hydrocarbon group including C1-C10 alkyl, C3-C10 cycloalkyl, C1-C10 alkoxy, C1-C10 carboxyl or hydroxyl; R a C(=O)-;R b C(=O)O-; or R c N(H)C(=O)-, and

[0144] R8~R 10 Each may be present independently, or at least two of them may be linked to form (or provide) a substituted or unsubstituted C4-C10 monocyclic aliphatic ring or a C4-C10 polycyclic aliphatic ring.

[0145] R a , R b and R c Each is independently a substituted or unsubstituted C1-C10 alkyl group.

[0146] The first compound may be included in an amount of about 1 wt % to about 5 wt %, for example, about 1 wt % to about 4 wt %, about 2 wt % to about 5 wt %, or about 2 wt % to about 4 wt %, based on the total amount of the electrolyte.

[0147] If the first compound is included in an amount less than about 1 wt % based on the total amount of the electrolyte, it may be difficult to effectively improve the thermal stability of the rechargeable lithium battery, and if the first compound is included in an amount greater than about 5 wt %, resistance during initial charge and discharge may be increased.

[0148] The second compound may be included in an amount of about 0.0001 wt % to about 2 wt %, for example, about 0.001 wt % to about 2 wt %, about 0.01 wt % to about 2 wt %, about 0.1 wt % to about 2 wt %, or about 0.1 wt % to about 1 wt %, based on the total amount of the electrolyte.

[0149] If the second compound is included in an amount less than about 0.0001 wt % based on the total electrolyte, polymerization of the first compound may not occur sufficiently, making it difficult to effectively improve the thermal stability of the rechargeable lithium battery, and if the second compound is included in an amount greater than about 2 wt %, side reactions may occur with the electrode or the electrolyte, resulting in problems with normal charging and discharging.

[0150] The weight ratio of the first compound to the second compound may be about 2:1 to about 10000:1, for example, about 3:1 to about 10000:1, about 3:1 to about 1000:1, about 3:1 to about 1000:1, about 3:1 to about 500:1, about 3:1 to about 100:1, about 3:1 to about 50:1, about 3:1 to about 40:1, or about 3:1 to about 30:1.

[0151] When the weight ratio is within the above range, thermal stability of the rechargeable lithium battery may be significantly improved.

[0152] Since the electrolyte additives are the same as those described above, a detailed description is not provided here.

[0153] Non-aqueous organic solvent

[0154] The nonaqueous organic solvent serves as a medium for transporting ions participating in the electrochemical reaction of the rechargeable lithium battery.

[0155] The non-aqueous organic solvent may include a carbonate solvent, an ester solvent, an ether solvent, a ketone solvent, an alcohol solvent or an aprotic solvent.

[0156] The carbonate solvents may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), ethylmethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), etc.

[0157] The ester solvents may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, γ-butyrolactone, decanoic acid lactone, valerolactone, mevalonolactone, caprolactone, and the like.

[0158] The ether solvent may include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, and the like.

[0159] Ketone solvents may include cyclohexanone and the like.

[0160] In addition, alcohol solvents may include ethanol, isopropanol, and the like.

[0161] Aprotic solvents may include nitriles (such as R-CN, wherein R is a C2-C20 straight chain, branched chain or cyclic hydrocarbon group, and may include a double bond, an aromatic ring or an ether bond); amides (such as dimethylformamide); dioxolanes (such as 1,3-dioxolane); sulfolane, etc.

[0162] The nonaqueous organic solvent may be used alone or in a mixture, and if the nonaqueous organic solvent is used in a mixture (eg, when the nonaqueous organic solvent is used in a mixture), the mixing ratio may be controlled or selected according to desired rechargeable lithium battery performance.

[0163] In addition, in the case of carbonate solvents, a mixture of cyclic carbonate and linear carbonate can be utilized. In this case, if cyclic carbonate and linear carbonate are mixed and utilized in a volume ratio of about 1:1 to about 1:9 (for example, when cyclic carbonate and linear carbonate are mixed and utilized in a volume ratio of about 1:1 to about 1:9), the electrolyte can show excellent or appropriate performance.

[0164] The nonaqueous organic solvent may further include an aromatic hydrocarbon organic solvent in addition to the carbonate-based solvent. At this time, the carbonate-based solvent and the aromatic hydrocarbon organic solvent may be mixed and used in a volume ratio of about 1:1 to about 30:1.

[0165] The aromatic hydrocarbon organic solvent may include an aromatic hydrocarbon compound represented by Chemical Formula I.

[0166] Chemical formula I

[0167]

[0168] In Formula I, R 201 ~R 206 may be each independently the same or different, and are selected from hydrogen, halogen, C1-C10 alkyl, C1-C10 haloalkyl, and / or combinations thereof (eg, appropriate combinations thereof).

[0169] Examples of aromatic hydrocarbon organic solvents may include benzene, fluorobenzene, 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, 1,2,3-trifluorobenzene, 1,2,4-trifluorobenzene, chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, iodobenzene, 1,2-diiodobenzene, 1,3-diiodobenzene, 1,4-diiodobenzene, 1,2,3-triiodobenzene, 1,2,4-triiodobenzene, toluene, fluorotoluene, 2,3-difluorobenzene, 1,3-dichlorobenzene, 1,4-diiodobenzene, 1,2,3-triiodobenzene, 1,2,4-triiodobenzene, Toluene, 2,4-difluorotoluene, 2,5-difluorotoluene, 2,3,4-trifluorotoluene, 2,3,5-trifluorotoluene, chlorotoluene, 2,3-dichlorotoluene, 2,4-dichlorotoluene, 2,5-dichlorotoluene, 2,3,4-trichlorotoluene, 2,3,5-trichlorotoluene, iodotoluene, 2,3-diiodotoluene, 2,4-diiodotoluene, 2,5-diiodotoluene, 2,3,4-triiodotoluene, 2,3,5-triiodotoluene, xylene and / or combinations thereof (e.g., appropriate combinations thereof).

[0170] The electrolyte may further include vinylene carbonate or an ethylene carbonate-based compound represented by Chemical Formula II as a cycle-life enhancing additive to improve the cycle life of the rechargeable lithium battery.

[0171] Chemical formula II

[0172]

[0173] In Chemical Formula II, R 207 and R 208 may be independently the same or different from each other and are selected from hydrogen, halogen, cyano, nitro and fluoroalkyl having 1 to 5 carbon atoms, provided that R 207 and R 208 At least one of them is a halogen, and R 207 and R 208 Not simultaneously (eg, synchronously) hydrogen.

[0174] Examples of ethylene carbonate-based compounds may include difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, fluoroethylene carbonate, etc. The amount of the additive for improving the cycle life may be utilized within an appropriate or suitable range.

[0175] Lithium salts

[0176] The lithium salt dissolved in the nonaqueous organic solvent supplies lithium ions in the rechargeable lithium battery, ensures basic operations of the rechargeable lithium battery, and improves the transfer of lithium ions between the positive electrode and the negative electrode.

[0177] Examples of lithium salts may include those selected from LiPF6, LiBF4, LiSbF6, LiAsF6, LiN(SO2C2F5)2, Li(CF3SO2)2N, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide, LiFSI), LiC4F9SO3, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2) (wherein x and y are natural numbers, such as integers of 1 to 20), one or more of lithium difluoro(bis(oxalato)phosphate, LiCl, LiI, LiB(C2O4)2 (lithium bis(oxalato)borate, LiBOB) and lithium difluoro(oxalato)borate (LiDFOB).

[0178] The lithium salt may be utilized in a concentration ranging 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 suitable or appropriate ion conductivity and viscosity, and thus may achieve excellent or appropriate performance, and may allow lithium ions to move efficiently.

[0179] Rechargeable lithium battery

[0180] One or more embodiments provide a rechargeable lithium battery including a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, a separator between the positive electrode and the positive electrode, and the aforementioned electrolyte.

[0181] The electrolyte is the same as described above, so a detailed description thereof is not provided here.

[0182] Figure 1 Schematic diagram showing a rechargeable lithium battery according to one or more embodiments. Figure 1 , the rechargeable lithium battery 100 includes a battery cell, which includes a positive electrode 114, a negative electrode 112 opposite to the positive electrode 114, a separator 113 between the positive electrode 114 and the negative electrode 112, and an electrolyte (not shown) of the rechargeable lithium battery that impregnates the positive electrode 114, the negative electrode 112 and the separator 113; a battery case 120 that accommodates the battery cell; and a sealing member 140 that seals the battery case 120.

[0183] Positive electrode

[0184] The positive electrode may include a positive electrode current collector and a positive electrode active material layer located on the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material, and may optionally further include a binder and / or a conductive material.

[0185] Any positive electrode active material may be applied without limitation as long as it is generally used in a rechargeable lithium battery. For example, the positive electrode active material may be a compound capable of inserting and extracting lithium, and may include a compound represented by any one of the following chemical formulas:

[0186] Li a A 1-b X b D2(0.90≤a≤1.8, 0≤b≤0.5);

[0187] 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);

[0188] Li a E 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05);

[0189] Li a E 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05);

[0190] Li a Ni 1-b-c Co b X c D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α≤2);

[0191] Li a Ni 1-b-c Co b X c O 2-α T α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2);

[0192] Li a Ni 1-b-c Co b X c O 2-α T2(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2);

[0193] Li a Ni 1-b-c Mr b X c D α (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.05,0<α≤2);

[0194] Li a Ni 1-b-c Mr b X c O 2-α T α (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.05,0<α<2);

[0195] Li a Ni 1-b-c Mr b X c O 2-α T2(0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.05,0<α<2);

[0196] Li a Ni b HAVE BEEN c G d O2(0.90≤a≤1.8,0≤b≤0.9,0≤c≤0.5,0.001≤d≤0.1);

[0197] Li a Ni b Co c Mr d G e O2(0.90≤a≤1.8,0≤b≤0.9,0≤c≤0.5,0≤d≤0.5,0.001≤e≤ 0.1);

[0199] Li a NiG b O2(0.90≤a≤1.8,0.001≤b≤0.1);

[0200] Li a CoG b O2(0.90≤a≤1.8,0.001≤b≤0.1);

[0201] Li a Mr 1-b G b O2(0.90≤a≤1.8,0.001≤b≤0.1);

[0202] Li a Mn2Gb O4(0.90≤a≤1.8, 0.001≤b≤0.1);

[0203] Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5);

[0204] QO2; QS2; LiQS2;

[0205] V2O5; LiV2O5;

[0206] LiZO2;

[0207] LiNiVO4;

[0208] Li (3-f) J2(PO4)3(0≤f≤2);

[0209] Li (3-f) Fe2(PO4)3(0≤f≤2);

[0210] Li a FePO4(0.90≤a≤1.8).

[0211] In the above chemical formula, A is selected from Ni, Co, Mn and / or a combination thereof (e.g., a suitable combination thereof); X is selected from Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements and / or a combination thereof (e.g., a suitable combination thereof); D is selected from O, F, S, P and / or a combination thereof (e.g., a suitable combination thereof); E is selected from Co, Mn and / or a combination thereof; T is (e.g., selected from) F, S, P and / or a combination thereof (e.g., a suitable combination thereof); G is selected from Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V and / or a combination thereof (e.g., a suitable combination thereof); Q is selected from Ti, Mo, Mn and / or a combination thereof (e.g., a suitable combination thereof); Z is selected from Cr, V, Fe, Sc, Y and / or a combination thereof (e.g., a suitable combination thereof); and J is selected from V, Cr, Mn, Co, Ni, Cu and / or a combination thereof (e.g., a suitable combination thereof).

[0212] The positive electrode active material may include, for example, lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium nickel cobalt oxide (NC), lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium nickel manganese oxide (NM), lithium manganese oxide (LMO), lithium iron phosphate (LFP), etc.

[0213] In one or more embodiments, the positive electrode active material may include a lithium cobalt oxide. When used together with the aforementioned electrolyte, the positive electrode using the lithium cobalt oxide as the positive electrode active material can exhibit a synergistic effect under a relatively high voltage design of 4.5V or in a fast charging system to suppress or reduce the resistance of the rechargeable lithium battery and improve the performance of the overall rechargeable lithium battery.

[0214] For example, the lithium cobalt-based oxide may be represented by Chemical Formula 5.

[0215] Chemical formula 5

[0216] Li a1 Co x1 M 1 (1-x1) O2

[0217] In Chemical Formula 5, 0.9≤a1≤1.8 and 0.7≤x1≤1, and M 1 It is one or more elements selected from Al, B, Ba, Ca, Ce, Cr, Cu, F, Fe, Mg, Mn, Mo, Ni, P, S, Se, Si, Sr, Ti, V, W, Y, Zn and Zr.

[0218] In Chemical Formula 5, x1 represents a molar content (eg, amount) of cobalt, and may be, for example, 0.8≤x1≤1, 0.9≤x1≤1, or 0.95≤x1≤1.

[0219] The average particle size of the positive electrode active material (D 50 ) may be about 1 μm to about 25 μm, for example, about 3 μm to about 25 μm, about 5 μm to about 25 μm, about 5 μm to about 20 μm, about 8 μm to about 20 μm, or about 10 μm to about 18 μm. The positive electrode active material having this average particle size range can be fully mixed with other components in the positive electrode active material layer, and a relatively high capacity and a relatively high energy density can be achieved. In this article, the average particle size (D) is measured by using a laser diffraction method with a particle size analyzer. 50 ), and the average particle size (D 50 ) may refer to the diameter of particles accounting for 50% by volume of the cumulative volume in a particle size distribution.

[0220] The positive electrode active material may be in the form of secondary particles made by aggregating a plurality of primary particles, or may be in the form of a single particle. In addition, the positive electrode active material may be spherical or nearly spherical, or may be polyhedral or amorphous.

[0221] The positive electrode active material layer may include a binder. The binder improves the bonding properties of the positive electrode active material particles to each other and the bonding properties of the positive electrode active material particles to the positive electrode current collector. Examples of the binder may be polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc., but are not limited thereto.

[0222] The content (eg, amount) of the binder in the positive electrode active material layer may be about 0.5 wt % to about 5 wt % based on the total weight of the positive electrode active material layer.

[0223] The positive electrode active material layer may include a conductive material. The conductive material may be used to impart conductivity (e.g., electrical conductivity) to the electrode, and any material that does not cause chemical changes (e.g., does not cause undesirable chemical changes in the rechargeable lithium battery) and conducts electrons may be used in the rechargeable lithium battery. Examples of conductive materials may include carbon-based materials (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.); metal-based materials containing copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fiber; conductive polymers (such as polyphenylene derivatives); and / or mixtures thereof (e.g., appropriate mixtures thereof).

[0224] The content (eg, amount) of the conductive material in the positive electrode active material layer may be about 1 wt % to about 5 wt % based on the total weight of the positive electrode active material layer.

[0225] Aluminum foil may be used as the positive electrode current collector, but the present disclosure is not limited thereto.

[0226] Negative electrode

[0227] 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 includes a negative electrode active material and may further include a binder and / or a conductive material (eg, an electron conductor).

[0228] The negative electrode active material may be a material that reversibly intercalates / deintercalates lithium ions, lithium metal, a lithium metal alloy, a material capable of doping / dedoping lithium, or a transition metal oxide.

[0229] Materials capable of reversibly embedding / desorbing lithium ions may include carbonaceous negative electrode active materials, such as crystalline carbon, amorphous carbon, and / or combinations thereof (e.g., suitable combinations thereof). The crystalline carbon may be graphite (such as amorphous, flaky, sheet-like, spherical, or fibrous natural graphite or artificial graphite). The amorphous carbon may be soft carbon, hard carbon, mesophase pitch carbonization product, calcined coke, etc.

[0230] The lithium metal alloy may include 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.

[0231] Materials capable of doping / dedoping lithium may be Si-based negative electrode active materials or Sn-based negative electrode active materials. The Si-based negative electrode active materials may include silicon, silicon-carbon composites, SiO x (0 < x ≤ 2), Si-Q alloys (where Q is an alkali metal, alkaline earth metal, Group 13 element, Group 14 element (but not Si), Group 15 element, Group 16 element, transition metal, rare earth element, and / or combinations thereof (e.g., suitable combinations thereof)), and the Sn-based negative electrode active materials may include Sn, SnO x (0 < x ≤ 2) (e.g., SnO2), Sn-R alloys (where R is an alkali metal, alkaline earth metal, Group 13 element, Group 14 element (but not Sn), Group 15 element, Group 16 element, transition metal, rare earth element, and / or combinations thereof (e.g., suitable combinations thereof)). At least one of these materials may be mixed with SiO2. The element Q and the element R may be selected from Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn (the element R is not Sn), In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, and / or combinations thereof (e.g., suitable combinations thereof).

[0232] The silicon-carbon composite may be, for example, a silicon-carbon composite including a core (including crystalline carbon and silicon particles) and an amorphous carbon coating disposed on the surface of the core. Crystalline carbon may be artificial graphite, natural graphite and / or a combination thereof (e.g., a suitable combination thereof). The amorphous carbon precursor may be coal pitch, mesophase pitch, petroleum pitch, coal oil, petroleum heavy oil or a polymer resin (such as a phenol resin, a furan resin or a polyimide resin). In this case, the content (e.g., amount) of silicon may be about 10wt% to about 50wt% based on the gross weight of the silicon-carbon composite. In one or more embodiments, the content (e.g., amount) of crystalline carbon may be about 10wt% to about 70wt% based on the gross weight of the silicon-carbon composite, and the content (e.g., amount) of amorphous carbon may be about 20wt% to about 40wt% based on the gross weight of the silicon-carbon composite. In one or more embodiments, the thickness of the amorphous carbon coating may be about 5nm to about 100nm. The average particle size (D) of the silicon particles may be about 100nm to about 100nm. 50 ) may be in the range of about 10 nm to about 20 μm. The average particle size (D 50 ) may be about 10 nm to about 200 nm. The silicon particles may exist in an oxidized form, and in this case, the atomic content (e.g., amount) ratio of Si:O in the silicon particles indicating the degree of oxidation may be a weight ratio of about 99:1 to about 33:67. The silicon particles may be SiO x particles, and in this case, SiO x The range of x in may be greater than 0 and less than about 2. In this specification, unless otherwise defined, the average particle size (D 50 ) indicates the diameter of the particles that account for about 50% by volume of the cumulative volume in the particle distribution.

[0233] The Si-based negative electrode active material or the Sn-based negative electrode active material may be mixed with the carbon-based negative electrode active material. When the Si-based negative electrode active material or the Sn-based negative electrode active material and the carbon-based negative electrode active material are mixed and used, the mixing ratio may be about 1:99 to about 90:10 by weight.

[0234] In the negative electrode active material layer, the negative electrode active material may be included in an amount of about 95 wt % to about 99 wt % based on the total weight of the negative electrode active material layer.

[0235] In one or more embodiments, the negative electrode active material layer further includes a binder, and optionally further includes a conductive material. Based on the gross weight of the negative electrode active material layer, the content (e.g., amount) of the binder in the negative electrode active material layer may be about 1wt% to about 5wt%. In one or more embodiments, if a conductive material is further included (e.g., when a conductive material is further included), based on the gross weight of the negative electrode active material layer, the negative electrode active material layer may include about 90wt% to about 98wt% of the negative electrode active material, about 1wt% to about 5wt% of the binder, and about 1wt% to about 5wt% of the conductive material.

[0236] The binder is used to bind the negative electrode active material particles well to each other and also to bind the negative electrode active material to the negative electrode current collector. The binder may be a water-insoluble binder, a water-soluble binder and / or a combination thereof (eg, a suitable combination thereof).

[0237] The water-insoluble binder may include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, ethylene propylene copolymers, polystyrene, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide and / or combinations thereof (e.g., appropriate combinations thereof).

[0238] The water-soluble binder may include a rubber binder or a polymer resin binder. The rubber binder may be selected from styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber and / or a combination thereof (e.g., a suitable combination thereof). The polymer resin binder may be selected from polyethylene oxide, polyvinyl pyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, ethylene propylene diene copolymer, polyvinyl pyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol and / or a combination thereof (e.g., a suitable combination thereof).

[0239] When a water-soluble binder is used as a binder in the negative electrode active material layer, a cellulose compound capable of imparting viscosity may be further included as a type of thickener. As a cellulose compound, one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose and alkali metal salts thereof may be mixed and utilized. The alkali metal may be Na, K or Li. Based on about 100 parts by weight of the negative electrode active material, the content (e.g., amount) of the thickener utilized may be about 0.1 parts by weight to about 3 parts by weight.

[0240] A conductive material is included to provide electrode conductivity, and any conductive material can be used as the conductive material unless it causes a chemical change. Examples of the conductive material include carbon-based materials (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.); metal-based materials containing copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fiber; conductive polymers (such as polyphenylene derivatives); and / or mixtures thereof (e.g., appropriate mixtures thereof).

[0241] The negative electrode current collector may include one selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and a combination thereof (eg, a suitable combination thereof).

[0242] Diaphragm

[0243] The separator 113 separates the positive electrode 114 and the negative electrode 112 and provides a transmission channel for lithium ions, and can be any commonly used separator in a lithium ion battery. The separator can have a relatively low resistance to ion transmission and has excellent or appropriate electrolyte impregnation. For example, the separator can include glass fiber, polyester, polyethylene, polypropylene, polytetrafluoroethylene and / or a combination thereof, and can have the form of a non-woven fabric or a textile. For example, in a lithium ion battery, a polyolefin polymer separator (such as a polyethylene / polypropylene separator) is mainly used. In order to ensure heat resistance or mechanical strength, a coated separator including a ceramic component or a polymer material can be used. Optionally, it can have a single-layer structure or a multilayer structure.

[0244] Rechargeable lithium batteries can be classified as lithium ion batteries, lithium ion polymer batteries, and lithium polymer batteries, depending on the presence of a separator and the type or kind of electrolyte utilized therein. Rechargeable lithium batteries can have a variety of shapes and sizes, and include cylindrical, prismatic, coin, or pouch-type or types of batteries, and can be thin film batteries or can be quite large in size. The structures and methods of making these batteries pertaining to the present disclosure are suitable in the art.

[0245] Hereinafter, examples and comparative examples of the present disclosure are described. However, the examples are for illustrative purposes and are not to be construed as limiting the present disclosure.

[0246] Example

[0247] Example 1

[0248] (Hereinafter, in the composition of the electrolyte, "wt%" is based on the total content (eg, amount) of the electrolyte (lithium salt + non-aqueous organic solvent + additives, etc.))

[0249] An electrolyte is prepared by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of about 20:10:70 to prepare a non-aqueous organic solvent, dissolving about 1.5M of LiPF6 lithium salt in the non-aqueous organic solvent, and adding about 2wt% of the first compound represented by Chemical Formula 2A (1,1'-(methylenebis-4,1-phenylene)bismaleimide) and about 0.1wt% of the second compound represented by Chemical Formula 4a (2,2'-azobis(isobutyronitrile)) thereto.

[0250] Chemical formula 2A

[0251]

[0252] Chemical formula 4a

[0253]

[0254] LiCoO2 as a positive electrode active material, polyvinylidene fluoride as a binder, and Ketjen black as a conductive material were mixed in a weight ratio of about 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, and then dried and compressed at about 110°C to manufacture a positive electrode.

[0255] Artificial graphite as a negative electrode active material, styrene-butadiene rubber as a binder, and carboxymethyl cellulose as a thickener were mixed in a weight ratio of about 97:1:2, and then the mixture was dispersed in distilled water to prepare a negative electrode active material slurry. The negative electrode active material slurry was coated on a Cu foil current collector of about 10 μm thick, and then dried and compressed at about 100°C to manufacture a negative electrode.

[0256] Subsequently, a separator having a polyethylene / polypropylene double-layer structure of about 25 μm thick was inserted between the positive electrode and the negative electrode to obtain an electrode assembly, the electrode assembly was loaded into a circular type or kind of battery case, and the prepared electrolyte was injected therein, manufacturing a rechargeable lithium battery cell according to Example 1.

[0257] Example 2 to Example 18

[0258] Each rechargeable lithium battery cell of Examples 2 to 18 was manufactured in substantially the same manner as in Example 1, except that the wt % of the first compound and the type (kind) and wt % of the second compound were changed as shown in Table 1.

[0259] Comparative Example 1

[0260] A rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 1, except that no additives were included.

[0261] Comparative Examples 2 to 4

[0262] A rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 1, except that the second compound was excluded, but the first compound was included at the wt % shown in Table 1.

[0263] Comparative Examples 5 to 7

[0264] Each rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 1, except that the first compound was excluded, but the second compound was included at the wt % shown in Table 1.

[0265] Table 1

[0266]

[0267]

[0268]

[0269] Experimental Example 1: Heat Exposure Evaluation

[0270] The rechargeable lithium battery cells of Examples 1 to 18 and Comparative Examples 1 to 7 were placed in a chamber, and then, the temperature change was examined by raising the temperature to about 140°C, about 141°C, about 142°C, and about 143°C at about 5°C / min and leaving them at these temperatures for about 1 hour, and the results are shown in Table 2.

[0271] After a total of three experiments were performed, if thermal runaway did not occur while the temperature was maintained (e.g., when thermal runaway did not occur while the temperature was maintained), it was marked as qualified, but if rapid thermal runaway occurred due to relatively high temperature exposure (e.g., when rapid thermal runaway occurred due to relatively high temperature exposure), it was marked as unqualified. The results are shown in Table 2.

[0272] In one or more embodiments, Figure 2 Graphs showing temperature changes and voltage changes according to heat exposure at about 143° C. in the rechargeable lithium battery cells according to Comparative Examples 1, 3, and 7, and Examples 6 and 10. FIG.

[0273] exist Figure 2 In FIG. 1 , the dotted line shows a voltage change according to time, and the solid line shows a temperature change according to time. Figure 2 , “_V” means voltage change according to time, and “_T” means temperature change according to time.

[0274] Table 2

[0275]

[0276]

[0277] Referring to Table 2, in each of the rechargeable lithium battery cells of Comparative Examples 1 to 7, thermal runaway was observed under heat exposure of about 140° C., but in Examples 1 to 18, thermal runaway was not observed under heat exposure of about 140° C. In addition, in each of the rechargeable lithium battery cells of Examples 4, 6, 8 to 11, and 15, thermal runaway was not observed under heat exposure of about 143° C.

[0278] refer to Figure 2 , in the rechargeable lithium battery cells of Comparative Examples 1, 3 and 7, and Examples 6 and 10, a sharp voltage drop was observed. In general, if a cylindrical battery is suddenly exposed to a relatively high temperature (for example, when a cylindrical battery is suddenly exposed to a relatively high temperature), gas is generated and its internal pressure is increased, which causes the battery protection circuit to operate, causing the current cut-off device (CID) to operate, thus causing a sharp voltage drop. Accordingly, the sharp voltage drop of the rechargeable lithium battery cells of Comparative Examples 1, 3 and 7, and Examples 6 and 10 confirms that the current cut-off device (CID) is activated by the gas generated due to the relatively high temperature exposure.

[0279] For example, even though the rechargeable lithium battery cells of Example 6 and Example 10 were exposed to a temperature of about 143° C., thermal runaway did not occur while the temperature of about 143° C. was maintained.

[0280] In contrast, in Comparative Examples 1, 3, and 7, sudden thermal runaway of about 600° C. or more occurred at about 46 minutes, about 61 minutes, and about 55 minutes, respectively.

[0281] Experimental Example 2: Evaluation of high temperature (60°C) storage

[0282] characteristic

[0283] The rechargeable lithium battery cells of Example 1, Example 3 and Example 10 were placed at a relatively high temperature of about 60° C. for about 10 days, about 20 days and about 30 days in a state of charge (SOC=about 100%) to evaluate relatively high temperature storage characteristics.

[0284] For example, the percentage (%) of each storage capacity after being left for about 10 days, about 20 days, and about 30 days relative to the initial capacity was calculated as the capacity retention rate (%), and the results are shown in Figure 3middle.

[0285] In one or more embodiments, the percentage (%) of each restored capacity after being placed for about 10 days, about 20 days, and about 30 days relative to the initial capacity is calculated as the capacity recovery rate (%), and the results are shown in Figure 4 In addition, the DC internal resistance increase rate (ΔDCIR, %) of the DC internal resistance relative to the initial resistance after being placed for about 10 days, about 20 days, and about 30 days was calculated, and the results are shown in Figure 5 In one or more embodiments, the open circuit voltage (OCV) change rate (ΔOCV, %) after about 10 days, about 20 days, and about 30 days of storage relative to the initial voltage is calculated, and the results are shown in Figure 6 middle.

[0286] refer to Figure 3 to Figure 6 , the rechargeable lithium battery cells of Example 1, Example 3 and Example 10 exhibit excellent or appropriate storage characteristics at relatively high temperatures.

[0287] Experimental Example 3: Cycle Life Evaluation at Room Temperature (25°C)

[0288] The rechargeable lithium battery cells of Example 1, Example 3 and Example 10 were charged at a constant current-constant voltage of about 1.6C and about 4.2V, cut off at about 0.04C, and left for about 10 minutes, and then discharged at a constant current of about 1.6C, cut off at about 2.5V, and left at room temperature (about 25°C) for about 10 minutes, and repeated 100 times to measure the discharge capacity. The discharge capacity retention rate (%) of the discharge capacity of the 100th cycle relative to the discharge capacity of the 1st cycle was calculated, and the results are shown in Figure 7 middle.

[0289] refer to Figure 7 , even after 100 cycles of charge and discharge at room temperature (e.g., when 100 cycles of charge and discharge at room temperature), the rechargeable lithium battery cells of Example 1, Example 3, and Example 10 each exhibited an excellent or appropriate discharge capacity retention rate (%) of about 90% or more.

[0290] In the present disclosure, "not including one or any component", "excluding one or any component", "containing no component", etc. means that the "component" is not added, selected or utilized as a component in the composition or compound, but due to other impurities and / or external factors, the "component" may still be included in an appropriate amount.

[0291] The battery management system (BMS) device and / or any other related device or component according to the embodiments of the present invention described herein may be implemented using any appropriate hardware, firmware (e.g., an application specific integrated circuit), software, or a combination of software, firmware, and hardware. For example, one or more appropriate components of the device may be formed on an integrated circuit (IC) chip or on a separate IC chip. Further, one or more appropriate components of the device may be implemented on a flexible printed circuit film, a tape carrier package (TCP), or a printed circuit board (PCB), or formed on a substrate. Further, one or more appropriate components of the device may be a process or thread running on one or more processors in one or more computing devices, executing computer program instructions and interacting with other system components for performing one or more appropriate functions described herein. The computer program instructions are stored in a memory that may be implemented in a computing device using a standard storage device (such as, for example, a random access memory (RAM)). The computer program instructions may also be stored in other non-transient computer-readable media (such as, for example, a CD-ROM, a flash drive, etc.). Furthermore, those skilled in the art will recognize that the functionality of one or more appropriate computing devices may be combined or integrated into a single computing device, or the functionality of a particular computing device may be distributed across one or more other computing devices without departing from the scope of the present disclosure.

[0292] In the present disclosure, "not including one or any component", "excluding one or any component", "free of component", etc. means that the "component" is not added, selected or utilized as a component in the composition / structure, but due to other impurities and / or external factors, the "component" may still be included in a less than appropriate amount.

[0293] Although the present invention has been described in conjunction with what is presently considered to be practical embodiments, it should be understood that the present disclosure is not limited to the disclosed embodiments. Rather, it is intended to cover one or more suitable modifications and equivalent arrangements included within the spirit and scope of the appended claims and their equivalents.

Claims

1. An electrolyte additive comprising: a polymer obtained by polymerizing the first compound represented by Chemical Formula 1, the first compound represented by Chemical Formula 2, or the first compound represented by Chemical Formula 3 as a monomer; and The second compound represented by Chemical Formula 4: Chemical formula 1 Chemical formula 2 Chemical formula 3 Chemical formula 4 In Chemical Formula 1, R1 is a substituted or unsubstituted C1-C4 alkylene, -C(O)CH2-, -ROR'OR-, -CH2OCH2-, -C(O)-, -O-, -OO-, -S-, -SS-, -S(O)-, -CH2S(O)CH2-, -(O)S(O)-, -CH2(C6H4)CH2-, -CH2(C6H4)O-, a substituted or unsubstituted phenylene, or a substituted or unsubstituted biphenylene, wherein R is a C1-C4 alkylene and R' is a C1-C4 alkylene, In Chemical Formula 2, R2 is a substituted or unsubstituted C1-C4 alkylene group, -C(O)-, -C(CH3)2-, -O-, -OO-, -S-, -SS-, -(O)S(O)- or -S(O)-, In Chemical Formula 3, R3 to R7 are each independently hydrogen, halogen, substituted or unsubstituted C1 to C6 alkyl, substituted or unsubstituted C2 to C6 alkenyl, substituted or unsubstituted C6 to C10 aryl, substituted or unsubstituted C2 to C6 ether, or substituted or unsubstituted C1 to C6 alkoxy, and In chemical formula 4, R8~R 10 Each is independently hydrogen; cyano; halogen; substituted or unsubstituted C1-C10 hydrocarbon group including C1-C10 alkyl, C3-C10 cycloalkyl, C1-C10 alkoxy, C1-C10 carboxyl or hydroxyl; R a C(=O)-;R b C(=O)O- or R c N(H)C(=O)-,R8~R 10 Each exists independently, or at least two of them are linked to form a substituted or unsubstituted C4-C10 monocyclic aliphatic ring or a C4-C10 polycyclic aliphatic ring, Where R a , R b and R c are each independently a substituted or unsubstituted C1-C10 alkyl group, and The electrolyte additive is used in a rechargeable lithium battery.

2. The electrolyte additive according to claim 1, wherein R1 is -ROR'OR-, -CH2OCH2-, substituted or unsubstituted phenylene or substituted or unsubstituted biphenylene, wherein R is C1-C4 alkylene and R' is C1-C4 alkylene.

3. The electrolyte additive according to claim 1, wherein The first compound represented by Chemical Formula 1 includes one or more compounds selected from the group consisting of compounds represented by Chemical Formula 1A to Chemical Formula 1E: Chemical formula 1A Chemical formula 1B Chemical formula 1C Chemical formula 1D Chemical formula 1E 4. The electrolyte additive according to claim 1, wherein R2 is substituted or unsubstituted C1-C4 alkylene, -C(O)- or -C(CH3)2-.

5. The electrolyte additive according to claim 1, wherein The first compound represented by Chemical Formula 2 includes one or more compounds selected from the compounds represented by Chemical Formula 2A to Chemical Formula 2C: Chemical formula 2A Chemical formula 2B Chemical formula 2C 6. The electrolyte additive according to claim 1, wherein R3 to R7 are each independently hydrogen, halogen or substituted or unsubstituted C1 to C6 alkoxy.

7. The electrolyte additive according to claim 1, wherein The first compound represented by Chemical Formula 3 includes one or more compounds selected from the compounds represented by Chemical Formulas 3A to 3C: Chemical formula 3A Chemical formula 3B Chemical formula 3C 8. The electrolyte additive according to claim 1, wherein The second compound represented by Chemical Formula 4 includes one or more compounds selected from the compounds listed in Group 1: Group 1 9. The electrolyte additive according to claim 1, wherein The second compound represented by Chemical Formula 4 includes one or more compounds selected from the compounds listed in Group 2: Group 2 10. The electrolyte additive according to claim 1, wherein The weight ratio of the first compound to the second compound is 2:1 to 10000:

1.

11. An electrolyte comprising: Non-aqueous organic solvents; Lithium salts; and The electrolyte additive according to any one of claims 1 to 10, wherein the monocyclic The electrolyte is used in a rechargeable lithium battery.

12. The electrolyte according to claim 11, wherein The first compound is included in an amount of 1 wt % to 5 wt % based on the total amount of the electrolyte.

13. The electrolyte according to claim 11, wherein The second compound is included in an amount of 0.0001 wt % to 2 wt % based on the total amount of the electrolyte.

14. 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 11 to 13.

Images