Rechargeable lithium battery

Abstract

Provided is a rechargeable lithium battery including: an electrolyte solution including a non-aqueous organic solvent, a lithium salt, and an additive; a positive electrode including a positive electrode active material; and a negative electrode including a negative electrode active material, in which the non-aqueous organic solvent includes less than about 5 wt% of ethylene carbonate based on the total weight of the non-aqueous organic solvent, the positive electrode active material includes a lithium nickel manganese-based oxide, and the additive is represented by Chemical Formula 1. Chemical formula 1 is as defined in the specification.

Description

Technical Field

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

[0002] Rechargeable lithium batteries are rechargeable and have an energy density per unit weight that is three or more times greater (i.e., at least three times greater) than comparable lead storage batteries (lead-acid batteries), comparable nickel-cadmium batteries, comparable nickel-metal hydride batteries, comparable nickel-zinc batteries, etc. Rechargeable lithium batteries can also be charged at high rates (e.g., to achieve relatively high energy densities) and are therefore commercially manufactured for use in laptop computers, cellular phones, power tools, electric bicycles, etc. Research into improving rechargeable lithium batteries (e.g., to provide additional energy density) is actively underway.

[0003] In addition, as information technology (IT) devices become increasingly high-performance, high-capacity batteries are desired or required, for example, by extending the voltage region to increase energy density to achieve high capacity. However, this approach may cause complications associated with oxidation of the electrolyte solution in the high voltage region, and thus deteriorate the performance of the positive electrode.

[0004] Recent progress has shown that cobalt-free lithium nickel manganese oxides can be used as positive electrode active materials. This new material does not contain cobalt, but contains nickel, manganese, etc. as the main components in its composition. Accordingly, positive electrodes including cobalt-free lithium nickel manganese oxides can be economical and can achieve high energy density, and therefore have received increasing attention as next-generation positive electrode active materials.

[0005] However, if a positive electrode including a cobalt-free lithium nickel manganese oxide is used in a high voltage environment (for example, when a positive electrode including a cobalt-free lithium nickel manganese oxide is used in a high voltage environment), the transition metal may be dissolved due to the structural collapse of the positive electrode. This may lead to internal gas generation, capacity reduction, etc. in the battery. Transition metal dissolution is easily aggravated in a high temperature environment, where the dissolved transition metal is precipitated on the surface of the negative electrode and may cause side reactions. As a result, an increase in battery resistance and degradation of battery cycle life and output characteristics may occur.

[0006] Therefore, the realization of a positive electrode including a cobalt-free lithium nickel manganese-based oxide requires (or requires) an electrolyte solution suitable for use under high voltage and high temperature conditions. Summary of the invention

[0007] Aspects of example embodiments relate to a rechargeable lithium battery that combines a positive electrode including a cobalt-free lithium nickel manganese-based oxide with an electrolyte solution that can effectively protect the positive electrode (i.e., the cobalt-free lithium nickel manganese-based oxide). The rechargeable lithium battery exhibits improved high voltage characteristics and high temperature characteristics by reducing the dissolution of transition metals under high voltage and high temperature conditions, and thus can inhibit or reduce the structural collapse of the positive electrode.

[0008] Some example embodiments provide a rechargeable lithium battery including an electrolyte solution including a non-aqueous organic solvent, a lithium salt, and an additive; a positive electrode including a positive electrode active material; and a negative electrode including a negative electrode active material,

[0009] wherein the non-aqueous organic solvent comprises less than about 5 wt % of ethylene carbonate based on the total weight of the non-aqueous organic solvent, the positive electrode active material comprises a lithium nickel manganese oxide, and

[0010] The additive includes a compound represented by Chemical Formula 1.

[0011] Chemical formula 1

[0012]

[0013] In Chemical Formula 1,

[0014] Ring A may be a substituted or unsubstituted C3-C6 heteroaryl group including at least one nitrogen atom or a substituted or unsubstituted C3-C6 heterocyclic group including at least one nitrogen atom,

[0015] L 1 may be substituted or unsubstituted C1-C3 alkylene, and

[0016] R 1 It may be hydrogen or a substituted or unsubstituted C1-C10 alkyl group.

[0017] The non-aqueous organic solvent may be a linear carbonate solvent (eg, may consist of only a linear carbonate).

[0018] The chain carbonate solvent can be represented by Chemical Formula 2.

[0019] Chemical formula 2

[0020]

[0021] In chemical formula 2,

[0022] R 2 and R 3 Each independently may be a substituted or unsubstituted C1-C20 alkyl group.

[0023] The non-aqueous organic solvent may be at least two of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), and ethylmethyl carbonate (EMC).

[0024] The nonaqueous organic solvent may include ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) in a volume ratio of about 0:100 to about 50:50.

[0025] Ring A of Chemical Formula 1 may be a substituted or unsubstituted imidazolyl group, a substituted or unsubstituted pyrrolyl group, a substituted or unsubstituted pyrazolyl group, a substituted or unsubstituted triazolyl group, a substituted or unsubstituted pyrrolidinyl group, a substituted or unsubstituted pyridinyl group, a substituted or unsubstituted pyrimidinyl group, a substituted or unsubstituted pyrazinyl group, a substituted or unsubstituted triazinyl group, a substituted or unsubstituted piperidinyl group, or a substituted or unsubstituted piperazinyl group.

[0026] Ring A of Chemical Formula 1 may include at least one double bond.

[0027] Chemical Formula 1 may be represented by any one of Chemical Formula 1A to Chemical Formula 1O.

[0028] Chemical formula 1A

[0029]

[0030] Chemical formula 1B

[0031]

[0032] Chemical formula 1C

[0033]

[0034] Chemical formula 1D

[0035]

[0036] Chemical formula 1E

[0037]

[0038] Chemical formula 1F

[0039]

[0040] Chemical formula 1G

[0041]

[0042] Chemical formula 1H

[0043]

[0044] Chemical formula 1I

[0045]

[0046] Chemical formula 1J

[0047]

[0048] Chemical formula 1K

[0049]

[0050] Chemical formula 1L

[0051]

[0052] Chemical formula 1M

[0053]

[0054] Chemical formula 1N

[0055]

[0056] Chemical formula 1O

[0057]

[0058] In Chemical Formula 1A to Chemical Formula 1O,

[0059] L 1 It may be a substituted or unsubstituted C1-C3 alkylene group,

[0060] R 1 and R 4 ~R 8 may be independently hydrogen or a substituted or unsubstituted C1-C10 alkyl group,

[0061] m1 can be an integer from 1 to 4.

[0062] m2 can be an integer from 1 to 3.

[0063] m3 can be an integer of 1 or 2, and

[0064] m4 can be one of integers 1 to 6.

[0065] The compound represented by Chemical Formula 1 may be selected from the compounds listed in Group 1.

[0066] Group 1

[0067]

[0068] The compound represented by Chemical Formula 1 may be included in an amount of about 0.05 to about 5.0 parts by weight based on 100 parts by weight of the total electrolyte solution including a lithium salt and a nonaqueous organic solvent except additives for a rechargeable lithium battery.

[0069] The electrolyte solution may further include at least one other additive selected from vinylene carbonate (VC), fluoroethylene carbonate (FEC), difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, vinylethylene carbonate (VEC), adiponitrile (AN), succinonitrile (SN), 1,3,6-hexanetrinitrile (HTCN), propene sultone (PST), propane sultone (PS), lithium tetrafluoroborate (LiBF4), lithium difluorophosphate (LiPO2F2) and 2-fluorobiphenyl (2-FBP).

[0070] The lithium nickel manganese-based oxide may include a cobalt-free lithium composite oxide represented by Chemical Formula 4.

[0071] Chemical formula 4

[0072] Li a Ni x Mn y M 1 z M 2 w O 2±b X c

[0073] In chemical formula 4,

[0074] 0.5≤a<1.8,0≤b≤0.1,0≤c≤0.1,0≤w<0.1,0.6≤x<1.0,0 <y<0.4,0<z<0.1,w+x+y+z=1,

[0075] M 1 and M 2 Each of them may independently be at least one element selected from Al, Mg, Ti, Zr, Cr, Sr, V, B, W, Mo, Si, Ba, Ca, Ce, Fe and Nb, and X may be at least one element selected from S, F, P and Cl.

[0076] Chemical formula 4 can be represented by Chemical formula 4-1.

[0077] Chemical formula 4-1

[0078] Li a Ni x1 Mn y1 Al z1 M 2w1 O 2±b X c

[0079] In chemical formula 4-1,

[0080] 0.5≤a<1.8,0≤b≤0.1,0≤c≤0.1,0≤w1<0.1,0.6≤x1<1.0,0 <y1<0.4,0<z1<0.1,w1+x1+y1+z1=1,

[0081] M 2 Each is independently at least one element selected from Mg, Ti, Zr, Cr, Sr, V, B, W, Mo, Si, Ba, Ca, Ce, Fe and Nb, and X is at least one element selected from S, F, P and Cl.

[0082] In Chemical Formula 4-1, 0.6≤x1≤0.79, 0.2≤y1≤0.39, and 0.01≤z1<0.1.

[0083] The negative electrode active material may include at least one of graphite and a Si composite.

[0084] The rechargeable lithium battery may have a charge upper limit voltage greater than or equal to about 4.35V.

[0085] Some example embodiments include (e.g., may be implemented) a rechargeable lithium battery that exhibits improved battery stability and cycle life characteristics by combining a positive electrode including a cobalt-free lithium nickel manganese oxide with an electrolyte solution that can effectively protect the positive electrode. In some embodiments, the protection can ensure the phase change safety of the positive electrode in a high temperature, high voltage environment and / or inhibit or reduce the decomposition of the electrolyte solution and / or side reactions with the electrode. In some embodiments, the protection can reduce gas generation and simultaneously (e.g., synchronously) inhibit or reduce the increase in the internal resistance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Figure 1 A schematic diagram for explaining a rechargeable lithium battery according to some example embodiments of the present disclosure.

[0087] Description of Reference Numerals

[0088] 100: Rechargeable lithium battery

[0089] 112: Negative electrode

[0090] 113: Diaphragm

[0091] 114: Positive electrode

[0092] 120: Battery housing

[0093] 140: Sealing member DETAILED DESCRIPTION

[0094] Hereinafter, the rechargeable lithium battery according to some example embodiments of the present disclosure will be described in more detail with reference to the attached drawings, wherein the same reference numerals refer to the same elements throughout, and their repeated description may not be provided. In this regard, the present embodiment may be modified to have different forms and should not be interpreted as being limited to the description set forth herein. On the contrary, the present disclosure is intended to cover all modifications, equivalents, and alternatives that fall within the spirit and scope of the present disclosure. Accordingly, the embodiments are described only by reference to the drawings to explain various aspects of the present description. However, these embodiments are only examples, and the present disclosure is not limited thereto, but is limited by the scope of the claims.

[0095] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Expressions such as "at least one of," if following a list of elements (e.g., when following a list of elements), modify the entire list of elements and do not modify the individual elements of the list.

[0096] If an element is described as being “on”, “connected to” or “coupled to” another element (for example, when an element is described as being “on”, “connected to” or “coupled to” another element), it will be understood that the element may be provided directly on the other element, or another element may be interposed between them. On the other hand, if an element is described as being “directly on” another element (for example, when an element is described as being “directly on” another element), another element is interposed between them.

[0097] It will be understood that although the terms "first", "second", and "third" may be used herein to describe one or more appropriate elements, components, regions, layers, and / or portions, these elements, components, regions, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, and / or portion from another element, component, region, layer, or portion. Therefore, without departing from the teachings of this specification, a first element, component, region, layer, or portion described herein may be referred to as a second element, component, region, layer, or portion.

[0098] As used herein, the singular forms "a", "an", and "the" are not to be construed as limited to the singular, but are intended to include the plural forms, including "at least one", unless the content (e.g., amount) is clearly indicated otherwise. As used herein, expressions such as "at least one", "one of", and "selected from", if preceding / following a list of elements (e.g., when preceding / following a list of elements), may modify the entire list of elements without modifying the individual elements of the list. For example, the expressions "at least one of a to c", "at least one of a, b, and c", and "at least one of a, b, and / or c" may indicate only a, only b, only c, both a and b (e.g., simultaneously), both a and c (e.g., simultaneously), both b and c (e.g., simultaneously), all of a, b, and c, or variations thereof.

[0099] If used in the detailed description (for example, when used in the detailed description), the terms "include", "includes", "including", "comprise", "comprises", "comprising", "having", "has" and / or "have" indicate the presence of stated features, regions, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and / or groups thereof.

[0100] 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 the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation illustrated in the drawings. For example, if the device in the drawings is flipped (e.g., when the device in the drawings is flipped), the elements described as "below" or "below" other elements or features are oriented "above" or "on" the other elements or features. Therefore, the example term "below" may encompass both (e.g., relative) orientations of above and below. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative terms used herein may be interpreted accordingly.

[0101] As used herein, the terms "use," "using," and "used" may be considered synonymous with the terms "utilized," "utilizing," and "utilized," respectively.

[0102] The term "may" will be understood to refer to "one or more embodiments of the present disclosure," some of which include the described elements, and some of which exclude the elements and / or include alternative elements. Similarly, alternative language such as "or" refers to "one or more embodiments of the present disclosure" that each includes the corresponding listed items.

[0103] The term "combinations thereof" may include mixtures, laminates, composites, copolymers, alloys, blends, reactants, and the like, of the components.

[0104] Unless otherwise defined, all terms used in this article (including chemical terms, technical terms and scientific terms) have the same meaning as those commonly understood by those skilled in the art to which the present disclosure belongs. In some embodiments, it will be further understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant field and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0105] In this context, "consisting essentially of" means that any additional components do not substantially affect the chemical, physical, optical, or electrical properties of the semiconductor film.

[0106] Furthermore, in this specification, the phrase "on a plane" or "plan view" means observing a target portion from the top, and the phrase "in a cross section" means observing a cross section formed by vertically cutting the target portion from the side.

[0107] definition

[0108] As used herein, if the particle is spherical (for example, when the particle is spherical), the term "particle size" of the particle refers to the average diameter, and if the particle is non-spherical (for example, when the particle is non-spherical), the term "particle size" of the particle refers to the average major axis length. The particle size of the particle can be measured using a particle size analyzer (PSA). The "particle size" of the particle is, for example, the "average particle size". The average particle size refers to, for example, the median particle size (D50). The median particle size (D50) is the particle size corresponding to 50% cumulative volume if the particle size distribution measured by the laser diffraction method is calculated by particles with a smaller particle size (for example, when the particle size distribution measured by the laser diffraction method is calculated by particles with a smaller particle size). In some embodiments, "particle size" or "average particle size" can be measured by transmission electron microscopy (TEM) images, scanning electron microscopy (SEM) images, etc.

[0109] If the particle size distribution measured by the laser diffraction method is calculated starting from particles with smaller particle sizes (eg, when the particle size distribution measured by the laser diffraction method is calculated starting from particles with smaller particle sizes), D50 refers to a particle size corresponding to 50% cumulative volume.

[0110] If the particle size distribution measured by the laser diffraction method is calculated starting from particles with smaller particle sizes (eg, when the particle size distribution measured by the laser diffraction method is calculated starting from particles with smaller particle sizes), D90 refers to the particle size corresponding to 90% cumulative volume.

[0111] If the particle size distribution measured by the laser diffraction method is calculated starting from particles with smaller particle sizes (eg, when the particle size distribution measured by the laser diffraction method is calculated starting from particles with smaller particle sizes), D10 refers to a particle size corresponding to 10% cumulative volume.

[0112] In some embodiments, the term "group" may refer to a group (i.e., column) of elements in the periodic table according to the International Union of Pure and Applied Chemistry ("IUPAC") group classification system of Groups 1 to 18. In some embodiments, the term "group" may refer to a chemical functional group, for example, an "alkyl group."

[0113] As used herein, the term "positive electrode active material" refers to an electrode material that can undergo lithiation and delithiation.

[0114] The term "negative electrode active material" as used herein refers to a negative electrode material that can undergo lithiation and delithiation.

[0115] As used herein, the terms "lithiate" and "lithiating" refer to the process of adding lithium to an electrode active material.

[0116] As used herein, the terms "delithiate" and "delithiating" refer to the process of removing lithium from an electrode active material.

[0117] As used herein, the terms "charge" and "charging" refer to the process of providing electrochemical energy to a battery.

[0118] As used herein, the terms "discharge" and "discharging" refer to the process of removing electrochemical energy from a battery.

[0119] The term "positive electrode" as used herein refers to the electrode that undergoes electrochemical reduction and lithiation during the discharge process.

[0120] The term "negative electrode" as used herein refers to the electrode that undergoes electrochemical oxidation and delithiation during the discharge process.

[0121] As used herein, if a specific definition is not otherwise provided (for example, when a specific definition is not otherwise provided), "substituted" means that at least one hydrogen of a substituent or a compound is replaced by deuterium, halogen, hydroxyl, amino, substituted or unsubstituted C1-C30 amine, nitro, substituted or unsubstituted C1-C40 silyl, C1-C30 alkyl, C1-C10 alkylsilyl, C6-C30 arylsilyl, C3-C30 cycloalkyl, C3-C30 heterocycloalkyl, C6-C30 aryl, C2-C30 heteroaryl, C1-C20 alkoxy, C1-C10 fluoroalkyl, cyano, or one or more combinations thereof.

[0122] In one example of the present disclosure, "substituted" means that at least one hydrogen of the 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. In some embodiments, in a specific example of the present disclosure, "substituted" means that at least one hydrogen of the substituent or compound is replaced by: deuterium, halogen, C1-C20 alkyl, C6-C30 aryl, C1-C10 fluoroalkyl or cyano. In some embodiments, in a specific example of the present disclosure, "substituted" means that at least one hydrogen of the substituent or compound is replaced by: deuterium, halogen, C1-C5 alkyl, C6-C18 aryl, C1-C5 fluoroalkyl or cyano. In some embodiments, in specific examples of the present disclosure, "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.

[0123] According to the types of separators and electrolyte solutions, rechargeable lithium batteries can be classified into lithium ion batteries, lithium ion polymer batteries, and lithium polymer batteries. According to the shape, rechargeable lithium batteries can also be classified into cylindrical, prismatic, coin-shaped or types, pouch-shaped or types, etc. In some embodiments, according to the size, the rechargeable lithium battery can be a block type or type and a film type or type. The structure and manufacturing method for rechargeable lithium batteries belonging to the present disclosure are very suitable in the art.

[0124] Herein, as an example of a rechargeable lithium battery, for example, a cylindrical rechargeable lithium battery is described. Figure 1 The structure of a rechargeable lithium battery according to some example embodiments is schematically shown. Figure 1According to some example embodiments, a rechargeable lithium battery 100 includes: a battery cell including a positive electrode 114, a negative electrode 112 facing the positive electrode 114, a separator 113 between the positive electrode 114 and the negative electrode 112, and an electrolyte solution impregnating the positive electrode 114, the negative electrode 112, and the separator 113; a battery case 120 accommodating the battery cell; and a sealing member 140 for sealing the battery case 120.

[0125] Hereinafter, a more detailed configuration of the rechargeable lithium battery 100 according to some example embodiments is described.

[0126] Rechargeable lithium battery

[0127] A rechargeable lithium battery according to some example embodiments includes an electrolyte solution, a positive electrode, and a negative electrode.

[0128] The electrolyte solution may include a nonaqueous organic solvent, a lithium salt, and an additive, the nonaqueous organic solvent may include less than about 5 wt % of ethylene carbonate based on the total weight of the nonaqueous organic solvent, and the additive may include a compound represented by Chemical Formula 1.

[0129] Chemical formula 1

[0130]

[0131] In Chemical Formula 1,

[0132] Ring A may be a substituted or unsubstituted C3-C6 heteroaryl group including at least one nitrogen atom or a substituted or unsubstituted C3-C6 heterocyclic group including at least one nitrogen atom,

[0133] L 1 may be substituted or unsubstituted C1-C3 alkylene, and

[0134] R 1 It may be hydrogen or a substituted or unsubstituted C1-C10 alkyl group.

[0135] The positive electrode may include a positive electrode active material including a lithium nickel manganese-based oxide.

[0136] In the case where the positive electrode active material includes lithium nickel manganese-based oxides (eg, cobalt-free lithium nickel manganese-based oxides), structural instability may be prevalent (eg, strong) under high voltage conditions, leading to solvent decomposition and dissolution of transition metals (especially Ni).

[0137] This transition metal dissolution phenomenon causes degradation in the performance of the positive electrode and a short circuit caused by the transition metal dissolution, which reduces the cycle life characteristics of the battery and causes a rapid increase in resistance.

[0138] However, if the disclosed electrolyte solution is used together (eg, when the disclosed electrolyte solution is used together), the reduction in cycle-life characteristics of the battery and the rapid increase in resistance may be alleviated.

[0139] In some embodiments, by using a positive electrode including a cobalt-free lithium nickel manganese-based oxide in an electrolyte solution containing less than about 5 wt % of ethylene carbonate based on the total weight of the non-aqueous organic solvent, transition metal dissolution can be reduced (e.g., effectively) under high voltage and high temperature conditions. In some embodiments, the use of the positive electrode and electrolyte solution disclosed herein results in suppression of collapse of the positive electrode structure and improves the high voltage characteristics and high temperature characteristics of the battery.

[0140] The nonaqueous organic solvent may be (eg, used as) a medium for transporting ions participating in an electrochemical reaction of a battery.

[0141] The non-aqueous organic solvent may be a carbonate solvent, an ester solvent, an ether solvent, a ketone solvent, an alcohol solvent or an aprotic solvent.

[0142] Carbonate solvents may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), etc. Ester solvents may include methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, decanoic acid lactone, mevalonate lactone, caprolactone, etc. Ether solvents may include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, etc. In some embodiments, ketone solvents may include cyclohexanone, etc. Alcohol solvents may include ethanol, isopropanol, etc., and aprotic solvents may include nitriles (such as R-CN, etc., wherein R is a hydrocarbon group having a C2-C20 straight chain, branched chain or ring structure, and may include a double bond, an aromatic ring or an ether bond), dioxolanes (such as 1,3-dioxolane, etc.), cyclopentane, etc.

[0143] A single non-aqueous organic solvent may be used or a combination of one or more thereof may be used. For example, if a non-aqueous organic solvent is used in a combination of one or more (e.g., when a non-aqueous organic solvent is used in a combination of one or more), the mixing ratio may be appropriately adjusted according to desired or appropriate battery performance, which is well understood by those skilled in the art.

[0144] As an example, the non-aqueous organic solvent may include less than about 5 wt % of ethylene carbonate based on the total weight of the non-aqueous organic solvent.

[0145] Based on the total weight of the non-aqueous organic solvent, if the content (e.g., amount) of ethylene carbonate is greater than or equal to about 5 wt % (e.g., when the content (e.g., amount) of ethylene carbonate is greater than or equal to about 5 wt %), the activity of Ni increases during high voltage operation, and the oxidation state of Ni has a strong tendency to be reduced from tetravalent to divalent. Therefore, ethylene carbonate with low oxidative stability may undergo oxidative decomposition, resulting in Ni dissolution and precipitation on the negative electrode.

[0146] For example, the nonaqueous organic solvent may be a linear carbonate solvent (eg, may consist of only linear carbonate). In this case, since the resistance increase rate during high temperature storage is significantly reduced, excellent or appropriate storage characteristics at high temperatures may be achieved.

[0147] In the present disclosure, the meaning of “consisting only of linear carbonates” indicates that the non-aqueous organic solvent is not mixed with another non-linear carbonate (e.g., cyclic carbonates, etc.), and the non-aqueous organic solvent includes a non-aqueous organic solvent belonging to the category of linear carbonate solvents (e.g., a non-aqueous organic solvent including one or more linear carbonates).

[0148] In some example embodiments, the linear carbonate solvent may be represented by Chemical Formula 2.

[0149] Chemical formula 2

[0150]

[0151] In chemical formula 2,

[0152] R 2 and R 3 Each independently may be a substituted or unsubstituted C1-C20 alkyl group.

[0153] For example, R in Formula 2 2 and R 3 may be independently substituted or unsubstituted C1-C10 alkyl, and for example R 2 and R 3 Each independently may be a substituted or unsubstituted C1-C5 alkyl group.

[0154] In some example embodiments, R in Formula 2 2 and R 3 Each independently may be substituted or unsubstituted methyl, substituted or unsubstituted ethyl, substituted or unsubstituted n-propyl, substituted or unsubstituted n-butyl, substituted or unsubstituted n-pentyl, substituted or unsubstituted isobutyl or substituted or unsubstituted neopentyl.

[0155] For example, the nonaqueous organic solvent according to a specific embodiment may be at least two selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), and ethylmethyl carbonate (EMC).

[0156] The non-aqueous organic solvent according to some embodiments may be a mixed solvent of dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC).

[0157] The nonaqueous organic solvent may include ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) in a volume ratio of about 0:100 to about 50:50.

[0158] In terms of improving battery characteristics, it may be more desirable that the non-aqueous organic solvent includes more than 50 volume % of dimethyl carbonate (DMC) based on the total volume of the non-aqueous organic solvent.

[0159] For example, the nonaqueous organic solvent may include ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) in a volume ratio of about 0:100 to about 40:60, about 0:100 to about 30:70, about 10:90 to about 40:60, or about 10:90 to about 30:70.

[0160] The non-aqueous organic solvent may further include an aromatic hydrocarbon organic solvent in addition to the linear carbonate-based solvent. Herein, the linear carbonate-based solvent and the aromatic hydrocarbon organic solvent may be mixed in a volume ratio of about 1:1 to about 30:1.

[0161] The aromatic hydrocarbon organic solvent may be an aromatic hydrocarbon compound represented by Chemical Formula 3.

[0162] Chemical formula 3

[0163]

[0164] In chemical formula 3, R 11 ~R 16 They may be independently the same or different and are selected from hydrogen, halogen, C1-C10 alkyl, C1-C10 haloalkyl, and one or more combinations thereof.

[0165] Specific examples of aromatic hydrocarbon organic solvents may be selected from benzene, fluorobenzene, 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, 1,2,3-trifluorobenzene, 1,2,4-trifluorobenzene, chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, iodobenzene, 1,2-diiodobenzene, 1,3-diiodobenzene, 1,4-diiodobenzene, 1,2,3-triiodobenzene, 1,2,4-triiodobenzene, toluene, 2-fluorotoluene, and the like. ,3-difluorotoluene, 2,4-difluorotoluene, 2,5-difluorotoluene, 2,3,4-trifluorotoluene, 2,3,5-trifluorotoluene, chlorotoluene, 2,3-dichlorotoluene, 2,4-dichlorotoluene, 2,5-dichlorotoluene, 2,3,4-trichlorotoluene, 2,3,5-trichlorotoluene, iodotoluene, 2,3-diiodotoluene, 2,4-diiodotoluene, 2,5-diiodotoluene, 2,3,4-triiodotoluene, 2,3,5-triiodotoluene, xylene and one or more combinations thereof.

[0166] The lithium salt dissolved in the non-aqueous organic solvent supplies lithium ions in the battery, ensures the general (e.g., basic) operation of the rechargeable lithium battery, and improves the transport of lithium ions between the positive electrode and the negative electrode. Examples of the lithium salt may include those selected from LiPF6, LiBF4, lithium difluoro(oxalato)borate (LiDFOB), LiPO2F2, LiSbF6, LiAsF6, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide: LiFSI), LiC4F9SO3, LiClO4, LiAlO2, LiAlCl4, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2) (wherein x and y are integers of 1 to 20), at least one of LiCl, LiI and LiB(C2O4)2 (lithium bis(oxalato)borate: LiBOB).

[0167] The concentration of the lithium salt may be in the range of about 0.1 M to about 2.0 M. If the lithium salt is included within the disclosed concentration range (e.g., when the lithium salt is included within the disclosed concentration range), the electrolyte may have excellent or appropriate performance and lithium ion mobility due to optimal or appropriate electrolyte conductivity and viscosity.

[0168] Ring A of Chemical Formula 1 may be a substituted or unsubstituted imidazolyl group, a substituted or unsubstituted pyrrolyl group, a substituted or unsubstituted pyrazolyl group, a substituted or unsubstituted triazolyl group, a substituted or unsubstituted pyrrolidinyl group, a substituted or unsubstituted pyridinyl group, a substituted or unsubstituted pyrimidinyl group, a substituted or unsubstituted pyrazinyl group, a substituted or unsubstituted triazinyl group, a substituted or unsubstituted piperidinyl group, or a substituted or unsubstituted piperazinyl group.

[0169] Ring A of Chemical Formula 1 may include at least one double bond.

[0170] Chemical Formula 1 may be represented by any one of Chemical Formula 1A to Chemical Formula 1O.

[0171] Chemical formula 1A

[0172]

[0173] Chemical formula 1B

[0174]

[0175] Chemical formula 1C

[0176]

[0177] Chemical formula 1D

[0178]

[0179] Chemical formula 1E

[0180]

[0181] Chemical formula 1F

[0182]

[0183] Chemical formula 1G

[0184]

[0185] Chemical formula 1H

[0186]

[0187] Chemical formula 1I

[0188]

[0189] Chemical formula 1J

[0190]

[0191] Chemical formula 1K

[0192]

[0193] Chemical formula 1L

[0194]

[0195] Chemical formula 1M

[0196]

[0197] Chemical formula 1N

[0198]

[0199] Chemical formula 1O

[0200]

[0201] In Chemical Formula 1A to Chemical Formula 1O,

[0202] L 1 It may be a substituted or unsubstituted C1-C3 alkylene group,

[0203] R 1 and R 4 ~R 8 may be independently hydrogen or a substituted or unsubstituted C1-C10 alkyl group,

[0204] m1 can be an integer from 1 to 4.

[0205] m2 can be an integer from 1 to 3.

[0206] m3 can be an integer of 1 or 2, and

[0207] m4 can be one of integers 1 to 6.

[0208] The compound represented by Chemical Formula 1 may be selected from the compounds listed in Group 1.

[0209] Group 1

[0210]

[0211] The additive may be included in an amount of about 0.05 parts by weight to about 5.0 parts by weight based on 100 parts by weight of the total electrolyte solution (lithium salt+non-aqueous organic solvent) excluding the additive for a rechargeable lithium battery.

[0212] For example, the additive may be included in an amount of about 0.05 parts by weight to about 3.0 parts by weight based on 100 parts by weight of the total electrolyte solution (lithium salt+non-aqueous organic solvent) excluding the additive for a rechargeable lithium battery.

[0213] For example, the additive may be included in an amount of about 0.1 to about 3.0 parts by weight, about 0.3 to about 3.0 parts by weight, about 0.5 to about 3.0 parts by weight, or about 0.5 to about 2.0 parts by weight based on 100 parts by weight of the electrolyte solution for a rechargeable lithium battery.

[0214] If the content (e.g., amount) range of the additive is as described (e.g., when the content (e.g., amount) range of the additive is as described), an increase in resistance at high temperature can be prevented or reduced, and a rechargeable lithium battery with improved cycle-life characteristics and output characteristics can be achieved.

[0215] On the other hand, the electrolyte solution may further include at least one other additive selected from vinylene carbonate (VC), fluoroethylene carbonate (FEC), difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, vinylethylene carbonate (VEC), adiponitrile (AN), succinonitrile (SN), 1,3,6-hexanetrinitrile (HTCN), propene sultone (PST), propane sultone (PS), lithium tetrafluoroborate (LiBF4), lithium difluorophosphate (LiPO2F2) and 2-fluorobiphenyl (2-FBP).

[0216] By further including other disclosed additives, the cycle life may be further improved or the gases generated from the positive electrode and the negative electrode may be effectively controlled or selected during high temperature storage.

[0217] The electrolyte solution for a rechargeable lithium battery may include other additives in an amount of about 0.2 to about 20 parts by weight, specifically about 0.2 to about 15 parts by weight, or for example about 0.2 to about 10 parts by weight, based on 100 parts by weight of the electrolyte solution for a rechargeable lithium battery.

[0218] If the amounts of other additives are as described above (for example, when the amounts of other additives are as described above), an increase in membrane resistance may be minimized or reduced, thereby contributing to improvement in battery performance.

[0219] The positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector, and the positive electrode active material layer includes a positive electrode active material.

[0220] The positive electrode active material may include a lithium nickel manganese-based oxide.

[0221] As an example, the lithium nickel manganese-based oxide may include at least one type or kind of the cobalt-free lithium composite oxide represented by Chemical Formula 4.

[0222] Chemical formula 4

[0223] Li a Ni x Mn y M 1 z M 2 w O 2±b X c

[0224] In chemical formula 4,

[0225] 0.5≤a<1.8,0≤b≤0.1,0≤c≤0.1,0≤w<0.1,0.6≤x<1.0,0 <y<0.4,0<z<0.1,w+x+y+z=1,

[0226] M 1 and M 2 Each of them may independently be at least one element selected from Al, Mg, Ti, Zr, Cr, Sr, V, B, W, Mo, Si, Ba, Ca, Ce, Fe and Nb, and X may be at least one element selected from S, F, P and Cl.

[0227] In the present disclosure, the cobalt-free lithium nickel manganese-based oxide as a positive electrode active material refers to a positive electrode active material mainly composed of nickel, manganese, etc., and cobalt is not included in the composition of the positive electrode active material.

[0228] The lithium composite oxide may have a coating on the surface, or may be mixed with another lithium composite oxide having a coating. The coating may include at least one coating element compound selected from an oxide of the coating element, a hydroxide of the coating element, an oxyhydroxide of the coating element, an oxycarbonate of the coating element, and a hydroxycarbonate of the coating element. The compound used for the coating may be amorphous or crystalline. The coating element included in the coating may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr and / or a mixture thereof. The coating may be provided by using these elements in the compound in a method that has no adverse effect on the characteristics of the positive electrode active material. For example, the method may include any coating method (e.g., spraying, dipping, etc.), but because it is very suitable for those skilled in the art, it is not described in more detail.

[0229] For example, Chemical Formula 4 can be represented by Chemical Formula 4-1.

[0230] Chemical formula 4-1

[0231] Li a Ni x1 Mn y1 Al z1 M 2 w1 O 2±b X c

[0232] In chemical formula 4-1,

[0233] 0.5 ≤ a < 1.8, 0 ≤ b ≤ 0.1, 0 ≤ c ≤ 0.1, 0 ≤ w1 < 0.1, 0.6 ≤ x1 < 1.0, 0 < y1 < 0.4, 0 < z1 < 0.1, w1 + x1 + y1 + z1 = 1,

[0234] M 2 each independently is at least one element selected from Mg, Ti, Zr, Cr, Sr, V, B, W, Mo, Si, Ba, Ca, Ce, Fe, and Nb, and X is at least one element selected from S, F, P, and Cl.

[0235] In some exemplary embodiments, in Chemical Formula 4-1, 0.6 ≤ x1 ≤ 0.9, 0.1 ≤ y1 < 0.4, and 0 < z1 < 0.1, or 0.6 ≤ x1 ≤ 0.8, 0.2 ≤ y1 < 0.4, and 0 < z1 < 0.1.

[0236] For example, in Chemical Formula 4-1, 0.6 ≤ x1 ≤ 0.79, 0.2 ≤ y1 ≤ 0.39, and 0.01 ≤ z1 < 0.1.

[0237] Based on the total weight of the positive electrode active material layer, the positive electrode active material may be included in an amount of about 90 wt% to about 98 wt%.

[0238] In some exemplary embodiments, the positive electrode active material layer may include a binder. In this case, based on the total weight of the positive electrode active material layer, the amount of the binder may be about 1 wt% to about 5 wt%.

[0239] The binder improves the binding characteristics between the positive electrode active material particles and the binding characteristics between the positive electrode active material particles and the positive electrode current collector. Examples thereof include, but are not limited to, 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, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc.

[0240] Al foil may be used as the positive electrode current collector, but is not limited thereto.

[0241] The negative electrode includes a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector and containing a negative electrode active material.

[0242] The negative electrode active material may include a material that reversibly intercalates / deintercalates lithium ions, lithium metal, a lithium metal alloy, a material capable of doping / dedoping lithium, or a transition metal oxide.

[0243] Materials that can reversibly embed / extract lithium ions may include carbon materials. The carbon materials can be any commonly used carbonaceous negative electrode active materials in rechargeable lithium batteries. Examples thereof can be crystalline carbon, amorphous carbon, or a mixture thereof. The crystalline carbon can be amorphous, or natural graphite or artificial graphite in the form of flakes, sheets, spheres, or fibers. The amorphous carbon can be soft carbon, hard carbon, mesophase pitch carbonization products, calcined coke, etc.

[0244] Lithium metal alloys include alloys of lithium and metals selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0245] Materials that can be doped / dedoped with lithium can be Si, Si-C composites, SiO x (0 < x ≤ 2), Si-Q alloys (where Q is an element selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements other than Si, Group 15 elements, Group 16 elements, transition metals, rare earth elements, and one or more combinations thereof), Sn, SnO x (0 < x ≤ 2), Sn-R 11 alloys (where R 11 is an element selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements other than Sn, Group 15 elements, Group 16 elements, transition metals, rare earth elements, and one or more combinations thereof), etc. At least one of these materials can be mixed with SiO2.

[0246] Elements Q and R 11 can be selected from Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn (R 11 does not include Sn), In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, and one or more combinations thereof.

[0247] Transition metal oxides can be vanadium oxides, lithium vanadium oxides, or lithium titanium oxides.

[0248] In some example embodiments, the negative electrode active material can include at least one selected from graphite and Si composites.

[0249] The Si composite can include a core containing Si-based particles and an amorphous carbon coating. For example, the Si-based particles can include (e.g., can be) selected from silicon particles, Si-C composites, SiO xAt least one (e.g., one or more) of (0 < x ≤ 2) and Si alloy.

[0250] For example, the core containing Si-based particles may include voids in the central portion, the radius of the central portion corresponding to about 30% to about 50% of the radius of the negative electrode active material, and the average particle size of the Si-based particles may be about 10 nanometers (nm) to about 200 nm.

[0251] In the present disclosure, the average particle size (D50) may be the particle size at a volume ratio of 50% in the cumulative size-distribution curve.

[0252] If the Si-based particles have an average particle size within this range (e.g., when the Si-based particles have an average particle size within this range), volume expansion during charge and discharge can be suppressed or reduced, and interruption of the conduction path due to particle fragmentation during charge and discharge can be prevented or reduced.

[0253] The core containing Si-based particles further includes amorphous carbon. Here, the central portion does not include amorphous carbon. For example, amorphous carbon may be present (alone) in the surface portion of the negative electrode active material.

[0254] In some embodiments, the surface portion refers to the region from the outermost surface of the central portion of the negative electrode active material to the outermost surface of the negative electrode active material.

[0255] In some embodiments, the Si-based particles are substantially uniformly included throughout the Si composite and may be present in the central portion and the surface portion at a substantially uniform concentration.

[0256] The amorphous carbon may be soft carbon, hard carbon, mesophase pitch carbonized product, calcined coke, or a combination of one or more thereof.

[0257] In one or more embodiments, the negative electrode active material may include (e.g., may be) a Si-C composite, where the Si-C composite may include silicon particles and crystalline carbon.

[0258] Based on the total weight of the Si-C composite, it may include silicon particles in an amount of about 1 wt% to about 60 wt%, for example, about 3 wt% to about 60 wt%.

[0259] Examples of the crystalline carbon may include graphite and may be, for example, natural graphite, artificial graphite, or a combination thereof.

[0260] The average particle size of the crystalline carbon may be about 5 micrometers (μm) to about 30 μm.

[0261] If the negative electrode active material includes (e.g., simultaneously) both graphite and Si composite (e.g., when the negative electrode active material includes (e.g., simultaneously) both graphite and Si composite), the graphite and Si composite may be included as a mixture (e.g., including the graphite and Si composite in the form of a mixture). In this case, the graphite and Si composite may be included in a weight ratio of about 99:1 to about 50:50.

[0262] In some embodiments, the graphite and the Si composite may be included in a weight ratio of about 97:3 to about 80:20 or about 95:5 to about 80:20.

[0263] The amorphous carbon precursor may include coal-based pitch, mesophase pitch, petroleum-based pitch, coal-based oil, petroleum-based heavy oil, or a polymer resin such as a phenol resin, a furan resin, or a polyimide resin.

[0264] 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.

[0265] In some example embodiments of the present disclosure, the negative electrode active material layer further includes a binder and optionally a conductive material. In the negative electrode active material layer, the content (e.g., amount) of the binder may be about 1wt% to about 5wt% based on the total weight of the negative electrode active material layer. If the negative electrode active material layer includes a conductive material (e.g., when the negative electrode active material layer includes a conductive material), the negative electrode active material layer includes 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.

[0266] The binder improves the bonding properties between the negative electrode active material particles and the bonding properties between the negative electrode active material particles and the negative electrode current collector. The binder includes a non-water-soluble binder, a water-soluble binder or a combination thereof.

[0267] The non-water-soluble binder may be selected from polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide or one or more combinations thereof.

[0268] The water-soluble binder can be a rubber binder or a polymer resin binder. The rubber binder can be selected from styrene-butadiene rubber (SBR), acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber and one or more combinations thereof. The polymer resin binder can be selected from polytetrafluoroethylene, ethylene propylene copolymer, polyethylene oxide, polyvinyl pyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, ethylene propylene diene copolymer, polyvinyl pyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol and one or more combinations thereof.

[0269] If a water-soluble binder is used as a binder in the negative electrode active material layer (for example, when a water-soluble binder is used as a binder in the negative electrode active material layer), a cellulose compound may be further used as a thickener to provide viscosity. Cellulose compounds include one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and alkali metal salts thereof. The alkali metal may be Na, K, or Li. Based on 100 parts by weight of the negative electrode active material, such a thickener may be included in an amount of about 0.1 parts by weight to about 3 parts by weight.

[0270] 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, etc.); metal-based materials including metal powders or metal fibers of copper, nickel, aluminum, silver, etc.; conductive polymers (such as polyphenylene derivatives); or mixtures thereof.

[0271] The negative electrode current collector may include one selected from the group consisting of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and one or more combinations thereof.

[0272] According to the type or kind of the rechargeable lithium battery, the rechargeable lithium battery may further include a separator between the negative electrode and the positive electrode. Examples of suitable separator materials include at least one selected from polyethylene, polypropylene, polyvinylidene fluoride and multilayers thereof (such as polyethylene / polypropylene double-layer separator, polyethylene / polypropylene / polyethylene three-layer separator and polypropylene / polyethylene / polypropylene three-layer separator).

[0273] The rechargeable lithium battery may have a charge upper limit voltage greater than or equal to about 4.35 V. For example, the charge upper limit voltage may be about 4.35 V to about 4.55 V.

[0274] Terms such as "substantially," "about," and "approximately" are used as relative terms, not as terms of degree, and are intended to account for the inherent deviations in measured or calculated values ​​that one of ordinary skill in the art would recognize. They may include the stated value as well as an acceptable range of deviation determined by one of ordinary skill in the art taking into account the limitations and errors associated with measuring that amount. For example, "about" may mean within one or more standard deviations of the stated value, or within ±30%, ±20%, ±10%, or ±5% of the stated value.

[0275] The numerical ranges disclosed herein include and are intended to disclose all subranges of the same numerical precision. For example, a range of "1.0 to 10.0" includes all subranges 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. Therefore, the applicant reserves the right to amend this specification (including the claims) to expressly set forth any subranges contained within the ranges expressly set forth herein.

[0276] Hereinafter, examples of the present disclosure and comparative examples are described. However, these examples are not to be construed as limiting the scope of the present disclosure in any sense.

[0277] Example

[0278] Manufacturing of rechargeable lithium battery cells

[0279] Example 1

[0280] LiNi as the positive electrode active material 0.75 Mn 0.23 Al 0.02 O2, polyvinylidene fluoride as a binder, and acetylene black as a conductive material were mixed in a weight ratio of 96:3:1 and then dispersed in N-methylpyrrolidone, thereby preparing a positive electrode active material slurry.

[0281] The positive electrode active material slurry was coated on a 15 μm thick Al foil, dried at 100° C. and pressed to manufacture a positive electrode.

[0282] The negative electrode active material slurry was also prepared by using a mixture of artificial graphite and Si composite in a weight ratio of 93:7 as the negative electrode active material, then mixing the negative electrode active material, styrene-butadiene rubber binder and carboxymethyl cellulose in a weight ratio of 98:1:1, and dispersing the obtained mixture in distilled water.

[0283] For the Si composite, coal pitch was coated on the surface of a core including artificial graphite and silicon particles.

[0284] The negative electrode active material slurry was coated on a 10 μm thick Cu foil, dried at 100° C. and pressed to manufacture a negative electrode.

[0285] The fabricated positive and negative electrodes were assembled with a 10 μm thick polyethylene separator to fabricate an electrode assembly, and an electrolyte solution was injected therein to fabricate a rechargeable lithium battery cell.

[0286] The electrolyte solution has the following composition.

[0287] The composition of the electrolyte solution

[0288] Lithium salt: 1.5M LiPF6

[0289] Non-aqueous organic solvent: ethyl methyl carbonate: dimethyl carbonate (by volume ratio, EMC:DMC=20:80)

[0290] Additive: 1 part by weight of the compound represented by Chemical Formula 1-1 (additive alone)

[0291] Chemical formula 1-1

[0292]

[0293] In the above composition of the electrolyte solution, "parts by weight" refers to the relative weight of the additive based on 100 parts by weight of the total electrolyte solution (lithium salt+nonaqueous organic solvent) excluding the additive.

[0294] Comparative Example 1

[0295] A rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 1, except that the compound represented by Chemical Formula 1-1 was not added to the composition of the electrolyte solution.

[0296] Comparative Example 2

[0297] A rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 1, except that 20 wt % of ethylene carbonate based on the total weight of the nonaqueous organic solvent was added to the composition of the electrolyte solution.

[0298] Comparative Example 3

[0299] A rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 1, except that 1 part by weight of fluoroethylene carbonate (FEC) was added to the composition of the electrolyte solution instead of the compound represented by Formula 1-1.

[0300] Example 2

[0301] A rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 1, except that the nonaqueous organic solvent was changed to 100 volume ratio of dimethyl carbonate, that is, only dimethyl carbonate was used as the nonaqueous organic solvent.

[0302] Example 3

[0303] A rechargeable lithium battery cell was manufactured in substantially the same manner as in Example 1, except that the mixing ratio of ethyl methyl carbonate and dimethyl carbonate was changed to a volume ratio of 40:60, respectively.

[0304] Comparative Examples 4 to 6

[0305] Rechargeable lithium battery cells were manufactured in substantially the same manner as in Example 1, Comparative Example 1, and Comparative Example 2, respectively, except that the positive electrode active material was changed to LiCoO 2 .

[0306] Comparative Examples 7 to 9

[0307] Rechargeable lithium battery cells were manufactured in substantially the same manner as in Example 1, Comparative Example 1 and Comparative Example 2, except that the positive electrode active material was changed to LiNi 0.5 Co 0.2 Al 0.3 O2.

[0308] Comparative Examples 10 to 12

[0309] Rechargeable lithium battery cells were manufactured in substantially the same manner as in Example 1, Comparative Example 1 and Comparative Example 2, except that the positive electrode active material was changed to LiNi 0.8 Co 0.1 Mn 0.1 O2.

[0310] Evaluation 1: Evaluation of storage characteristics at high temperatures

[0311] The initial DC internal resistance (DCIR) of the rechargeable lithium battery cells according to Examples 1 to 3 and Comparative Examples 1 to 12 was measured as ΔV / ΔI (voltage change / current change), and then, the DC internal resistance was measured again by setting the maximum energy state inside the rechargeable lithium battery cell to a fully charged state (SOC 100%) and then storing it at a high temperature of 60°C for 30 days, thereby calculating the DCIR increase rate (%) according to Equation 1, and the results are shown in Table 1.

[0312] Equation 1

[0313] DCIR increase rate = {(DCIR after 30 days) / (initial DCIR)}×100

[0314] Evaluation 2: Evaluation of high temperature cycle life characteristics

[0315] The rechargeable lithium battery cells according to Examples 1 to 3 and Comparative Examples 1 to 12 were charged and discharged once at 0.2 C, and then, were measured with respect to charge and discharge capacities.

[0316] In some embodiments, the rechargeable lithium battery cells manufactured according to Examples 1 to 3 and Comparative Examples 1 to 12 were charged at a charge upper limit voltage of 4.4V and then discharged at 0.2C to 2.5V under constant current conditions to measure initial discharge capacity.

[0317] The discharge capacity was measured by performing 200 cycles of charge and discharge again under the conditions of 0.33C charge (CC / CV, 4.4V, 0.025C cutoff) / 1.0C discharge (CC, 2.5V cutoff) and 45° C. The ratio of the discharge capacity to the initial discharge capacity is shown in Table 2 as the capacity recovery rate (%, recovered).

[0318] Assessment 3: Measurement of gas generation after high temperature storage

[0319] The rechargeable lithium battery cells according to Example 1 and Comparative Examples 1 to 12 were left standing at 60° C. for 7 days, and then the gas generation (mL) on the 1st and 7th days was measured using refinery gas analysis (RGA), the increase rate was calculated, and the results are shown in Table 3.

[0320] The increase rate was calculated according to Equation 2.

[0321] Equation 2

[0322] Increase rate = {(gas production on the 7th day) / (gas production on the 1st day)}×100

[0323] Table 1

[0324]

[0325] Table 2

[0326]

[0327] Table 3

[0328]

[0329] Referring to Tables 1 to 3, in the composition of the combined electrolyte solution and the positive electrode active material according to the present application, the DCIR increase rate is reduced, and both high temperature storage characteristics and high temperature charge and discharge characteristics are improved (eg, simultaneously).

[0330] In some embodiments, the amount of gas generated in the rechargeable lithium battery cell according to the embodiment is significantly reduced after being stored at a high temperature.

[0331] In the present disclosure, "not including an 'ingredient' or any 'ingredient'", "excluding an 'ingredient' or any 'ingredient'", "no 'ingredient'" and the like mean that the 'ingredient' is not added, selected or used as an ingredient in the composition, but due to other impurities and / or external factors, the 'ingredient' may be included in an appropriate amount.

[0332] Any suitable hardware, firmware (e.g., an application specific integrated circuit), software, or a combination of software, firmware, and hardware may be used to implement the battery management system (BMS) device and / or any other related device or component according to an embodiment of the present disclosure described herein. For example, the various components of the device may be formed on an integrated circuit (IC) chip or on separate IC chips. In addition, the various 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. In addition, 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 for performing the various functions described herein. The computer program instructions are stored in a memory, which 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-temporary computer-readable media (such as, for example, a CD-ROM, a flash drive, etc.). Moreover, those skilled in the art should recognize that, without departing from the scope of the present disclosure, the functions of various computing devices may be combined or integrated into a single computing device, or the functions of a particular computing device may be distributed on one or more other computing devices.

[0333] While the subject matter of the present disclosure has been described in connection with what are presently considered to be practical example embodiments, it should be understood that the disclosure is not limited to the disclosed embodiments, but on the contrary is intended to cover one or more suitable modifications and equivalent arrangements included within the spirit and scope of the claims and their equivalents.

Claims

1. A rechargeable lithium battery comprising: an electrolyte solution including a non-aqueous organic solvent, a lithium salt and an additive; a positive electrode, including a positive electrode active material; as well as A negative electrode comprising a negative electrode active material, Wherein, based on the total weight of the non-aqueous organic solvent, the non-aqueous organic solvent comprises less than 5 wt % of ethylene carbonate, The positive electrode active material includes a lithium nickel manganese oxide, and The additive includes a compound represented by Chemical Formula 1: Chemical formula 1 and Wherein, in Chemical Formula 1, Ring A is a substituted or unsubstituted C3-C6 heteroaryl group including at least one nitrogen atom or a substituted or unsubstituted C3-C6 heterocyclic group including at least one nitrogen atom, L 1 is a substituted or unsubstituted C1-C3 alkylene group, and R 1 It is hydrogen or substituted or unsubstituted C1-C10 alkyl.

2. The rechargeable lithium battery of claim 1, wherein: The non-aqueous organic solvent is a chain carbonate solvent.

3. The rechargeable lithium battery of claim 2, wherein: The chain carbonate solvent is represented by Chemical Formula 2: Chemical formula 2 and Wherein, in Chemical Formula 2, R 2 and R 3 Each is independently a substituted or unsubstituted C1-C20 alkyl group.

4. The rechargeable lithium battery of claim 1, wherein: The non-aqueous organic solvent is at least two selected from the group consisting of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate and ethylmethyl carbonate.

5. The rechargeable lithium battery of claim 1, wherein: The non-aqueous organic solvent includes ethyl methyl carbonate and dimethyl carbonate in a volume ratio of 0:100 to 50:

50.

6. The rechargeable lithium battery of claim 1, wherein: Ring A of Chemical Formula 1 is a substituted or unsubstituted imidazolyl group, a substituted or unsubstituted pyrrolyl group, a substituted or unsubstituted pyrazolyl group, a substituted or unsubstituted triazolyl group, a substituted or unsubstituted pyrrolidinyl group, a substituted or unsubstituted pyridinyl group, a substituted or unsubstituted pyrimidinyl group, a substituted or unsubstituted pyrazinyl group, a substituted or unsubstituted triazinyl group, a substituted or unsubstituted piperidinyl group, or a substituted or unsubstituted piperazinyl group.

7. The rechargeable lithium battery of claim 1, wherein: Ring A of Chemical Formula 1 includes at least one double bond.

8. The rechargeable lithium battery of claim 1, wherein: Chemical formula 1 is represented by any one of Chemical formulas 1A to 1O: Chemical formula 1A Chemical formula 1B Chemical formula 1C Chemical formula 1D Chemical formula 1E Chemical formula 1F Chemical formula 1G Chemical formula 1H Chemical formula 1I Chemical formula 1J Chemical formula 1K Chemical formula 1L Chemical formula 1M Chemical formula 1N Chemical formula 1O and Among them, in Chemical Formula 1A to Chemical Formula 1O, L 1 is a substituted or unsubstituted C1-C3 alkylene group, R 1 and R 4 ~R 8 are each independently hydrogen or substituted or unsubstituted C1-C10 alkyl, m1 is an integer from 1 to 4. m2 is an integer from 1 to 3. m3 is an integer of 1 or 2, and m4 is one of integers 1 to 6.

9. The rechargeable lithium battery of claim 1, wherein: The compound represented by Chemical Formula 1 is selected from the compounds listed in Group 1: Group 1 10. The rechargeable lithium battery of claim 1, wherein: The compound represented by Chemical Formula 1 is included in an amount of 0.05 parts by weight to 5.0 parts by weight based on 100 parts by weight of the total electrolyte solution including the lithium salt and the nonaqueous organic solvent excluding the additive.

11. The rechargeable lithium battery of claim 1, wherein: The electrolyte solution further includes at least one other additive selected from vinylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, vinylethylene carbonate, adiponitrile, succinonitrile, 1,3,6-hexanetrinitrile, propene sultone, propane sultone, lithium tetrafluoroborate, lithium difluorophosphate and 2-fluorobiphenyl.

12. The rechargeable lithium battery of claim 1, wherein: The lithium nickel manganese-based oxide includes a cobalt-free lithium composite oxide represented by Chemical Formula 4: Chemical formula 4 Li a Ni x Mn y M 1 z M 2 w O 2±b X c ,and Among them, in chemical formula 4, 0.5≤a<1.8,0≤b≤0.1,0≤c≤0.1,0≤w<0.1,0.6≤x<1.0,0 <y<0.4,0<z<0.1,w+x+y+z=1, M 1 and M 2 Each is independently at least one element selected from the group consisting of Al, Mg, Ti, Zr, Cr, Sr, V, B, W, Mo, Si, Ba, Ca, Ce, Fe and Nb, and X is at least one element selected from S, F, P and Cl.

13. The rechargeable lithium battery of claim 12, wherein: Chemical formula 4 is represented by Chemical formula 4-1: Chemical formula 4-1 Li a Ni x1 Mn y1 Al z1 M 2 w1 O 2±b X c ,and Among them, in chemical formula 4-1, 0.5≤a<1.8,0≤b≤0.1,0≤c≤0.1,0≤w1<0.1,0.6≤x1<1.0,0 <y1<0.4,0<z1<0.1,w1+x1+y1+z1=1, Each M 2 is independently at least one element selected from Mg, Ti, Zr, Cr, Sr, V, B, W, Mo, Si, Ba, Ca, Ce, Fe and Nb, and X is at least one element selected from S, F, P and Cl.

14. The rechargeable lithium battery of claim 13, wherein: In Chemical Formula 4-1, 0.6≤x1≤0.79, 0.2≤y1≤0.39, and 0.01≤z1<0.

1.

15. The rechargeable lithium battery of claim 1, wherein: The negative electrode active material includes at least one of graphite and a Si composite.

16. The rechargeable lithium battery of claim 1, wherein: The rechargeable lithium battery has a charge upper limit voltage greater than or equal to 4.35V.

Images